Energy - Efficiency in the Cement Industry

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Proceedings of a seminar organised by the Commission of the European Communities, Directorate-General for Energy and CIMPOR Cimentos de Portugal E.P. with the co-operation of Cembureau European Cement Association, and held in Oporto, Portugal, 6–7 November 1989. Particular thanks are due to Mr V.Teixeira Lopo, President of CIMPOR, and to Mr A.Soares Gomes, Director, for help in the organisation of this symposium, and to NIFES Consulting Group for editorial assistance.

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY Edited by

J.SIRCHIS Directorate-General for Energy, Commission of the European Communities, Brussels, Belgium

ELSEVIER APPLIED SCIENCE LONDON and NEW YORK

ELSEVIER SCIENCE PUBLISHERS LTD Crown House, Linton Road, Barking, Essex IG11 8JU, England This edition published in the Taylor & Francis e-Library, 2005. “To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.” Sole Distributor in the USA and Canada ELSEVIER SCIENCE PUBLISHING CO., INC. 655 Avenue of the Americas, New York, NY 10010, USA WITH 26 TABLES AND 55 ILLUSTRATIONS © 1990 ECSC, EEC, EAEC, BRUSSELS AND LUXEMBOURG British Library Cataloguing in Publication Data Energy efficiency in the cement industry. 1. European Community countries. Industries. Energy. Conservation I.Sirchis, J. 658.26 ISBN 0-203-21565-6 Master e-book ISBN

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PREFACE

The existence of significant uncertainty as to the long-term prospects for energy supply and demand following the rapid fall in oil prices, has stimulated both the international energy situation as well as that of the Community and made it essential that the substantial progress already made in restructuring the Community’s energy economy be maintained and, if necessary, reinforced. The European Energy Policy objectives for the year 1995 call for adequate energy supply, controlled energy prices and increased environmental concern. All of these constraints necessitate the rational exploitation of the primary energy forms by the EEC Member States. The above objectives can be attained either by energy saving or by increased energy efficiency, or finally through the development of new technologies to augment both saving and efficiency. Better insulation, heat and material recycling, or application of improved processes, are typical examples. Cement production is one of the most energy intensive sectors and requires a great quantity of energy. Although much progress has already been achieved today in the field of the energy economy in the cement industry in EEC countries, some stages of cement production still offer opportunities for further improvement.

CONTENTS

PREFACE

v

OPENING SESSION Chairman: V Teixeira Lopo, President CIMPOR OPENING ADDRESS—ENERGY POLICY OF THE COMMISSION OF THE EUROPEAN COMMUNITIES F KINDERMANN, Commission of the European Communities

2

OPENING SPEECH—A POLICY OF ENERGY EFFICIENCY NUNO RIBEIRO DA SILVA, Secretary of State for Energy

6

FIRST SESSION Chairman: Professor Veiga Simao, President of LNETI ENERGY SAVING AND ENVIRONMENTAL IMPACT IN THE CEMENT INDUSTRY A SOARES GOMES, CIMPOR, Cimentes de Portugal, Portugal

16

ENERGY OUTLOOK IN WEST GERMANY’S CEMENT INDUSTRY A SCHEUER and S SPRUNG, Forschungsinstitut der Zementindustrie, Düsseldorf 30, Federal Republic of Germany

20

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY JESUS GARCIA DEL VALLE and ALEJANDRO TORRES Asland Tecnologia SA, Madrid, Spain

29

ENERGY OUTLOOK IN THE JAPANESE CEMENT INDUSTRY YUKIO NAKAJIMA, Nihon Cement Co Ltd., Tokyo, Japan

42

DISCUSSION

49

SECOND SESSION—PART 1—SPECIFIC TECHNOLOGIES AND CEC DEMONSTRATION PROJECTS Chairman: J Sirchis, Commission of the European Communities TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT RECOVERY IN CEMENT PLANTS E STEINBISS, KHD Humboldt Wedag AG, Cologne, Federal Republic of Germany

52

DISTRICT HEATING BASED ON WASTE HEAT FROM CLINKER COOLER BO AHLKVIST, Cementa AB, Sweden

64

vii

HEAT RECOVERY ON THE SMOKE OF THE CEMENT KILN AND UTILIZATION OF THE RECOVERED ENERGY J-F BOUQUELLE, Département Projets Ciments d’Obourg, Obourg, Belgium

69

UTILIZATION OF WASTE HEAT FROM THE CEMENT ROTARY KILN K-H WEINERT, Interatom GmbH, Bergisch Gladbach, Federal Republic of Germany

74

ENERGY SAVING BY UTILISATION OF HIGH EFFICIENCY CLASSIFIER FOR GRINDING AND COOLING OF CEMENT ON TWO MILLS AT CASTLE CEMENT (RIBBLESDALE) LIMITED, CLITHEROE, LANCASHIRE, UK P F PARKES, Castle Cement, Clitheroe, United Kingdom

81

DISCUSSION

86

SECOND SESSION—PART 2—ENGINEERING AND ENERGY MANAGEMENT ‘HOLDERBANK’S’ ENERGY MANAGEMENT IN THE 1990s M BLANCK, ‘Holderbank’ Management and Consulting Ltd, Holderbank, Switzerland

90

ENGINEERING AND ENERGY SAVINGS J DUMAS, CITEC, Guerville, France

102

ENERGY SAVINGS IN CEMENT KILN SYSTEMS E BIRCH, F L Smidth and Co AS, Valby, Denmark

112

HIGH ENERGY SAVINGS THROUGH THE USE OF A NEW HIGH-PERFORMANCE HYDRAULIC COMPONENT THE K-TECH PROCESS M PALIARD and M MAKRIS, CLE, Paris La Defense, France G MENARDI and M BAILLY, Ciments de Champagnole, Dole, France

125

ENERGY MANAGEMENT IN THE UK CEMENT INDUSTRY T M LOWES and K W BEZANT, Blue Circle Industries plc, Greenhithe, Kent, United Kingdom

136

WASTE GAS HEAT RECOVERY IN CEMENT PLANTS M NETO, Souselas Cement Plant, CIMPOR, Portugal

144

DISCUSSION

148

THIRD SESSION—RODND TABLE DISCUSSION 152 Chairman: Professor Mario Nina, University of Lisbon K W Bezant, BLUE CIRCLE, United Kingdom F Aellen, HOLDERBANK, Switzerland Professor G Parisakis, University of Athens, Greece J Sirchis, Commission of the European Communities E Steinbiss, KHD, BR Deutschland H Takakusaki, NIHON CEMENT CO, Japan CLOSING SESSION Chairman: V Teixeira Lopo, President of CIMPOR CONCLUSIONS D QUIRKE, CEMBUREAU CEC, Ministry of Industry

158

viii

LIST OF PARTICIPANTS

160

INDEX OF AUTHORS

189

OPENING SESSION Chairman: V Teixeira Lopo, President CIMPOR

OPENING ADDRESS “ENERGY POLICY OF THE COMMISSION OF THE EUROPEAN COMMUNITIES” F.KINDERMANN Head of Division Commission of the European Communities Directorate-General for Energy Technology Directorate Programme Management: Solid Fuels and Energy Saving

If one goes back to the roots of the European Community, one discovers that two of the three Treaties deal, partly of completely, with energy. – The Treaty establishing the EUROPEAN COAL AND STEEL COMMUNITY (ECSC) was signed in Paris in 1951. – The Treaty establishing the EUROPEAN ATOMIC ENERGY COMMUNITY (EAEC or EURATOM) was signed in Rome in 1957. Therefore, one could say that, from the beginning, the founders of Europe regarded energy as a very important brick for the construction of a real Community and one could even say that a good deal of the integrated Common Market has already been realised for coal, steel and uranium. In spite of this, I must admit that there was virtually no real common energy policy existing before the first oil crisis back in 1973. Until then, the energy sector in the Community was characterised by twelve distinct national markets with a matching number of national policies which were more or less coordinated on the European level. It was only under the influence of the 1973 shock that quantified targets for selected, energy carriers in the Community were defined. Of course, the main concern was, at that time, to substitute oil and to reduce the dependency of the Community. Therefore, alternative energy sources, solid fuels and energy efficiency, played a very important role, and it should be noted that the latter two are of very great Importance to the cement industry, which is characterised by a high energy demand. Anyway, once the European Energy Policy was established, it led very quickly to tangible results. In fact, the consumption of imported oil was halved within 10 years, from 62% in 1973 to 31% in 1985, and energy efficiency raised by ±20%. This forced the Commission to propose new targets for 1995, which were adopted by the Council in September 1986.

OPENING ADDRESS

3

I will not go into these in great detail as we all know very well that, since then, conditions on the energy market have changed drastically: oil prices went down, as did coal prices on the world market; natural gas is pressing for a higher market share; and in some countries, nuclear energy continues to expand. In addition to this, there is more and more concern about the environment and particularly about the so-called greenhouse effect. For these reasons, I would like to mention today only three of the present targets which are of importance to industry and will remain vaild in future too: – Energy efficiency will remain one of the most important topics of Energy Policy, for the reasons of economy as well as of environment. – Solutions are needed to establish a well-balanced relationship between Energy and the Environment. This will certainly become even more important in future and will require adequate developments. – Technology will have to play an extremely important role in achieving the targets. It is quite interesting to see that these three items were amongst the Community’s targets from the beginning. Yet, importance shifted from aspects of substitution and economics to the protection of the environment. In addition, there are the requirements of the integrated Market for Energy or, in short, 1992. In fact, National as well as Community policies have to change to meet the situation that will exist after 1992. Energy is an area where this transition now has to be made in order to have the integrated European energy market followed by a true common energy policy at Community level. The integration of Europe’s internal energy market is already underway, and a number of new initiatives in this field have been launched since the beginning of 1989. These include new schemes for greater crossfrontier trade and competition in the gas and electricity sectors, a mechanism for taking into account the European dimension In the planning of major energy investments, and a new system allowing the transparency of gas and electricity prices. Other measures to ensure the 1992 deadline will follow. In the longer term, however, it will be the Commission’s task to propose to the Member States, a concise framework for an effective Community energy policy. Therefore, a new review of longterm energy prospects is at present underway, i.e., the 2010 study. A first disscussion paper, entitled “Major Themes in Energy to 2010” was realised by the Commissioner for Energy, Mr Antonio Cardoso e Cunha, at the World Energy Conference in Montreal last September. As the Commissioner said in Montreal, the essential question facing all of us is the following: “Can we continue to develop the world’s energy supplies, on a secure and economic basis, sufficient to maintain economic growth while at the same time ensuring that the global environment is protected and indeed improved?” The “Major Themes in Energy” shows possible alternative paths for our energy future. One is a “convential route” with continuing growth in energy consumption and CO2 emissions. Another path suggests a way of controlling energy consumption and its environmental impact whilst maintaining economic growth—in other words, meeting the challenge of sustainable energy growth. In the months ahead, the Commission will refine its analysis, taking into account the reactions in the Community and Internationally, to this document. However, the preliminary findings were already communicated to the international press in early October. In this context, it is quite clear that the major constraint, or challenge, facing energy policy in the next few years will be the environmental one. We have seen, for example, how much attention was focused on this issue recently at the world Energy Conference in Montreal. But we cannot afford either to neglect the more traditional concern of energy policy makers, that of security of supply. This is particularly true at a time when the world’s need for oil and other energy supplies continues to grow steadily month by month. Action

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

must be taken to curb this trend in order to preserve as far as possible our energy resource base and to protect the global environment. With these two fundamental concerns in mind, it is quite clear that the major priority will have to be given to energy efficiency. In order to reduce the growth in energy consumption and the associated pollution. Thus, the political target is set, and all possible actions have to be put in hand to reach it. Of course, this covers political and financial measures as well as technology but for reasons of time, I would like to concentrate on the latter one. An excellent technical base to build upon has been created by the Community’s energy demonstration programme which was set up in 1978 and concentrated on three major areas: – Energy saving or energy efficiency; – New and renewable energy sources; – Solid fuels. I feel I shouldn’t go into too much detail because the area of interest to your industry will be presented during the course of the next two days. But, in order to let you have an idea of what is involved, I would like to give you some figures on the total programme and on the part devoted to energy saving. 1978–1989

Total Programme

Energy Saving

%

Number of projects Total aid (MECU)

1,698 881.7

738 327.7

43.5 37.2

These figures prove that in the past, the Community already gave the appropriate attention to all the possibilities of saving energy and improving energy efficiency. Let me just say that the main technical areas were, and still are: – Buildings – Transport – Industry The demonstration programme, as it stands now, has pratically come to an end. An independent evaluation was carried out last year which highlighted the remarkable results obtained in the different areas, but also said that much more should be done to assure a widespread use of the results, and to match the new targets for energy at the beginning of the next century. The Commission adopted this line and, consequently, proposed to the Council that the replacement for the existing demonstration and hydrocarbon technology scheme should be the THERMIE programme, a new programme for demonstrating new energy technologies and promoting their commercialisation in the European market. As for the current programmes, THERMIE will concentrate on the state beyond R&D by providing risk finance for the testing of new energy technologies on a nearly commercial scale. It will however, be more selective than its predecessor schemes and give more emphasis to the promotion and replication of successfully demonstrated technologies. The current plan is that the Energy Council and the European Parliament should give their consent to this new programme in time for it to start at the beginning of next year.

OPENING ADDRESS

5

THERMIE will cover a wide range of energy technologies including most renewable energies and energy efficiency technologies, as well as clean coal combustion and hydrocarbon projects. These technologies will certainly have a key role to play in assuring the Community’s energy future and preserving its environment. They will also be of benefit to other countries outside Europe, particularly in the Third World where the Community has cooperation and technology transfer programmes. I have no doubt that companies, universities, and all those working in the Community in the energy saving field will find that THERMIE provides a valuable new impetus to, and support for their pioneering activities. In addition, the launching of THERMIE proves that the Community in conscious of tomorrow’s problems and is ready to take its responsability.

A POLICY OF ENERGY EFFICIENCY SPEECH OF HIS EXCELLENCY THE SECRETARY OF STATE FOR ENERGY NUNO RIBEIRO DA SILVA

The aim of the Common Energy Policy in Portugal for the period up to 1995 is a 20% saving energy consumption. If this is accomplished, it will represent: – An annual saving of at least 2 million tons equivalent of oil (14 million barrels), corresponding to something like Esc. 45bn at today’s prices. – A consequent drop in the emission of CO2 into the atmosphere of around 6 million tons annually. Such an increase in energy efficiency will have repercussions in the balance of payments and will lead to improvements in the quality of the environment; there will, moreover, be an increase in the competitiveness of the economy in general. To these results would have to be added the internal and external effects of these moves to diversify sources, above all those which aim to maximise the use of natural and renewable resources. These were, and indeed are, the fulcral points in the search for technical and financial instruments for a concerted policy of energy efficiency, set up with the consumer in mind. The first element which ties these instruments together is the fact that they aim to support operations, systems and sectors which are highly diversified and made up of a large number of distinct, financially limited activities. This is a broad characterisation of the system of energy demand, a system requiring not only special attention but also a framework for the unavoidable “confrontation” with the supply side. The complementary nature of the various instruments should also of course be mentioned: Firstly, as already mentioned, they open the door to all forms of rational association of the three most important components of a logical use of energy in the widest sense: – the management of energy at the level of the company or the region;

A POLICY OF ENERGY EFFICIENCY

7

– the conservation of energy in the widely differentiated systems used by the consumer; – the diversification of sources of energy with all those possible forms available for its use and transformation. Secondly, within the purview of these instruments, as in no other, we find all those Involved in economic activities which it is really important to mobilize, from central and local administration to companies, cottage industries and services. The only exception here is the domestic consumer, who of course demands a very different type of action. Finally, the new Instruments contribute even more to efficient and continuing support at all stages of the prjects, beginning at R.D. & D. or in studies of project potential, continuing through the legal framework and feasibility studies and ending at the point of incentives to investment. But perhaps the most important of the aspects referred to here is the fact that the new instruments contribute overall to providing a reply to many of the questions which are raised in a continuing policy of energy efficiency: – A more exhaustive study of the resources of the country, including not only renewable energy but also the potential of economy of energy at end-user level; – Diffusion of tried and tested energy technology and useful equipment into all areas of production and use of energy: – Increase in production and quality of equipment, systems and energy services; – Development of decentralised means of electrical energy production with a resultant drop in the costs and thereby the creation of profit potential at local or company level. – Breaking down of legal barriers which hinder full use of resources, along with rulings on the contractual conditions of supply of energy to the public network: – Increase in the viability, through financial support of energy projects, which may otherwise be of only minor interest from the narrow vieuwpoint of the consumer: – Creation of incentives and opportunities for new forms of financing, over and above supports and loans, all with a view to maximising results. Here specifically we can refer to the suppliers of energy, who finance their system through third parties. From among these instruments, of a somewhat varied nature, the following can be pointed out: I) SYSTEMS OF FINANCIAL INCENTIVES 1. 2. 3. 4.

SIURE incentive system for the rational use of energy The Community programme VALOREN The Community programme of pilot studies in the field of energy PEDIP

II) REGULATORY INSTRUMENTS 1. Regulation of independant production of electrical energy 2. Regulation on the management of energy consumption 3. Regulation on the thermal characteristics of buildings

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

III) SYSTEM OF ALTERNATIVE FINANCING – Financing by third parties I would like to take advantage of the present occasion, albeit in a necessary summary fashion, to take stock of the situation regarding these instruments in the two years of a coherent energy policy which has gone hand in hand with a community policy for this sector. 1. SIURE incentive system for the rational use of energy This is “par excellence” the national system of support for the rational use of energy, having taken over in May 1988 from the previous system (SEURE) which had been operative since August 1986. From among the alterations introduced the following are worthy of mention: – An open door policy for all sectors of activity (with the exception of domestic consumption); – Application to operations and cost centres as diversified as pilot studies, projects and R & D operations—over and above investment in fixed assets; – Articulation with regulations in force for major consumers (to the standa&rd of the RGCE norms); – Probality of application to the system of “financing by third parties); – Increase in joint participation when operations can be included in the VALOREN programme; – Progressive increase in the incentives for R.D. & D. operations with those of the existing Community programme of demonstration projects and with the THERMIE programme in the future. With three applications already accepted (August and September 1988 and January 1989) and two underway (May and September of this year) the system has already proved that it is much better adapted to the requirements and characteristics of its potential beneficiaries. The situation is at present as follows: . The total investment made up to now (Esc. 17.8bn.) has already way outstripped the values of the old systems, as indeed has the number of applications, already up to 217, as compared with 245 in the two years of SEURE. . The 82 operations approved in the three phases already completed is more than those of SEURE (75); moreover approvals represent 66% acceptance of the projects proposed, whereas in SEURE the rate was a mere 31%. . There are already 30 applications in the area of feasibility studies (an area not considered before). There have been 8 approvals and 10 are under consideration. Of the 30, 25 relate to cost control and plans for rationalization of energy; The diversification of sectors and activities is manifest in those projects which have been approved, with emphasis on textiles and clothing, ceramics and glass, foodstuffs, agrilture and fishing. . From the total of applications approved, the forecast of annual energy economy is around 40.500 tons of oil, corresponding to Esc. 911m in foreign currency. In geographical terms, it is the regions of the centre and the north which show a more entrepreneurial spirit, if we consider the level of investment and subsidies which have been given. Stange to say, it is the Lisbon region that has seen most operations (28), possibly because there are many pilot studies included, and projects with a high level of energy economy.

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. As a final point, the Esc. 1.16bn in subsidies already given represent nearly 29% of the total investment associated with the same companies; by comparison, during the period of SEURE the total was 19%. As has already been mentioned, increases in the subsidies may be possible, as well as joint financing through the VALOREN programme, as long as the operations come within the terms of reference of the programme. I would like to take this opportunity to announce that the whole community and national process has been completed, allowing for joint financing of SIURE through PEDIP, in the case of applications which cannot be included in the VALOREN programme, but which relate to the operations to be developed in the extracting and transformation industries. In this way, there will be close on Esc. 2.2bn available between 1989 and 1992 as reinforcement of the budget available for SIURE, and Esc. 2.4bn through the country’s Budget applications for the same period. 1.2) THE COMMUNITY VALOREN PROGRAMME This programme is available to provide finance for operations which aim at rational use of energy in small and medium industrial and services companies. The aim is above all to stimulate regions of various potential renewable energy sources. The programme has been operative from October 1987 for applications for public or comparable infrastructures. The VALOREM programme can, as has been seen, provide joint finance for incentives which are taken through SIURE, as long as the operation is included among its objectives, in terms of investment, budget and others regulations. The joint financing began in 1988, immediately after the first applications for SIURE funding. The committed funds in this operation of the VALOREM programme valid until the end of 1991, were Esc. 5.6bn up to the end of this past September, and this has already gone beyond the 50% of the Esc. 10. 5bn earmarked for these specific projects. On this situation the following points can be made: The VALOREM programme has already supplied close on Esc. 915m through SIURE, in terms of the 3 applications which have already been processed. This sum corresponds to approximately 79% of the subsidies provided by SIURE and up to 26% of funds available through the VALOREM programme for these projects up to December 1991. Given that SIURE only started in August 1988, this information should be more widely known, with a view to attracting more applications. . The commitments undertaken in participation in energy projects relating to the public or comparable infrastructures represent already 68% ot the total allowed for. There are in fact regions, such as the North and Centre, wich show greater dynamism and which have already gone beyond the forecats, while the Alentejo, the Algarve and above all the Azores are still considerably behinhand. In terms of type of energy or sector of activity, it is found that the use of biomass (kindling wood, stalks from vines, biogas…) is the source of the largest number of applications. These have already gone beyond the forecast limit and have made it necessary to reappraise the distribution of available funds. The projects for the use of water have not been confirmed, because the authorisation for such use has not come through yet. These projects are already sufficient to take up all of the funds available for this area. For this reason, and also because the average duration of these investments goes beyond the end of 1991 have meant that studies are underway with the Portuguese Small Hydro-Power Association to find alternative

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ways for the VALOREM programme to be associated with the investment which was caused by the new legislation regarding the independent producer. The VALOREN programme has been available as finance for important actions involving energy sources which are part of the country’s natural resources and the technologies which are associated with them, as well as information relating to the possibilites of rational use of energy (for example, through finance for the IAPMEI “Energy-bus”). The steady increase in the proportion of energy consumption in the GPD, as well as the recent boom in consumption, bearing especially on domestic consumption and services, has led to the VALOREN programme becoming actively involved in a major campaign to inform the public— in fact all consumers— that energy must be used sparingly and that there should be greater awareness of the need for its rational use. 1.3) COMMUNITY PROGRAMME FOR DEMONSTRATION PROJECTS This programme was created and is run by the Office of the Director-General of Energy (DG XVII) of the European Community Commission. It is at the heart of this seminar and since 1975 has been responsible for financing important projects in various energy sectors during the precompetition stage. It is also the Community programme which is best-known among Portuguese industrialists, according to a survey conducted by the Ministry of Energy and industry. This is by no means by chance. Since 1986, the date of the our accession to the Community, we have participated—in the sense that the Portuguese entrepreneurs, in conjonction with Universities or national laboratories have made applications to the programme. Since great care always been given to the choice and preparation of good projects, the percentage of approvals has always been high, and this has allowed us to get support for a percentage which has always been higher than our overall weight in the total. In the four competitions which have taken place, a total of Esc. 2.55bn in support has been given to Portuguese projects, representing 22% of the total investment of nearly Esc. 11.5bn. However, in the last two years alone, the support has totalled Esc. 1.8bn, out of a total of Esc. 9.8bn of total project costs. In terms of the “quota” received, and without taking into account the part of the competitions relating to solid fuels (that is, carbon fuels), in which, understandably, we saw only 3 out of the 4 projects approved, the grants awarded represented in the last two years 8.5% and 7.7% of the available funds. For the values relating to the past years, a large proportion is taken up by the CIMPOR project which is presented here today. Apart from its innovation in European and Community terms, there are two aspects to the projects which are worthy of mention here. Firstly, there is the adoption and adaptation of a Japanese technology for the cement industry which is of great interest in the energy sector. Secondly, there is the system of recovery of heat from gases from the furnace exhausts, which will also contribute to diminishing pollution in terms or dust and the combustion products of coal. Next year, the present demonstration programme will be replaced by the recently approved THERMIE programme, which draws on a different philosophy, due in large measure to the suggestions which we put forward. In this way, innovatory projects will continue to be supported, with an assessment procedure which is more rigorously controlled. Moreover, THERMIE will open up the possibility of support to projects already presented, where these are put forward in new contexts, geographical, economic, social and energy oriented within, and in some cases outside the EEC.

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This new approach will undoubtedly bring in its train more and better opportunities for Portuguese projects and for the diffusion of the results obtained through the present programme. Less widely-known, but capable of being very interesting at the level of back-up for these Community programme is the part of SIURE which allows for incentives for demonstration projects and pilot studies, as well as research and development of new forms of production and distribution of energy. From among 14 applications presented for this tranche of SIURE, 4 to date have already been approved, 3 are under review, 2 were rejected and another 3 were asked to reformulate their terms and resubmit. From among the projects already approved, the CIMPOR project already referred to looms largest. Exceptionally, this project will receive an additional grant of 100m escudos, not only in view of the risk involved but also the great scope for reproduction, even if only at a national level. II.1) REGULATION FOR INDEPENDENT PRODUCTION OF ELECTRICITY The launch of this regulation in May 1988 was a real success, such was the interest among individuals, companies and local authorities. The conviction that decentralised production by agents independent from EDP would reduce production costs for small units and stimulations could lead to 6.500GWh/year being made available. This led to the new legislation, which is innovatory above all in terms of the full and rational legal framework in which this activity can now be undertaken. The recent law on production is applicable to all forms of the production electricity from any renewable source, or from recycled thermal effluents. However, in the early days up to the present, the speediest and most exciting reply has been in the area of water resources. The main characteristics of this legislation are well known, and I consider it more interesting on this occasion to refer to some points which give an idea of the interest it has awoke. The right to use any water, as indeed any utility in the public domain, is subject to specific authorisation. Up to now, 702 requests to produce electrical energy have been put in to the Office of the Director General of SEARN. The difficulties in the management of water resources which this avalanche has created are not difficult to imagine. The 370 requests which have a solid foundation and obvious know-how of the field and his use represent close on 1.015MW, greater than the biggest power station In Portugal (Alto Lindoso, which generates 625MW). Forecasts point to a production of approximately 4.025GWh, i.e. around 20% of the domestic electricity production in 1988. The authorisation process is not limited to the use to which the water is to be put. Among other things, it is essential that the interested parties cleraly justify their technical and economic aims; that there should be no other intentions for the same site; and that different uses are not being considered for the same water resources. As for any overlaps, in terms of requests made by different groups for the same site, the decision on which takes priority should not be based simply on legal points. We have found that in many cases a solution has been or is being found through discussions with the interested parties. There have also been examples or collaboration from the official services involved. Given the large number of interested parties—companies, local authorities and individuals—and given the variety of motives know-how and financial capacity, I consider it of paramount importance to encourage all forms of collaboration which are being found. This applies to the equating of interests, technical expertise and management of the resources in question.

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

I would like here to draw attention to the creation of the Portuguese Association of Small Hydro Producers. This I consider to be indicative of the dynamism of the sector and the professionalism and enthusiasm of those involved. The initial members of the Association bear the responsability of making it a real partner In the dialogue between the various entities in the sector. The Association must consider all applications from would-be members, and should even encourage those who work in the sector and are interested in their activities for widely differing reasons. The question of how representative the Association happens to be is fundamental to relations with third parties and for this reason, with in the Association, mutual understanding and interchange of ideas among the members become much more important. Should this spirit prevail I have no doubt at all the Small Hydro-Electric scheme will be of benefit to everybody involved. This whole process shwows how business peopple are reacting to the liberalization of the energy sector which is underway in our country. As far as the use of small power stations for the production of electricity is concerned, all the 6 requests for authorisations which have been handed in to the Office of the Director General of Energy relate to premises destined for the generation of heat and electricity. The fuels to be used are forest waste in 4 cases and gas in each of the other two. The total power potential is around 130MW, with a forecast annual production of the order of 800GWh. This demonstrates how much greater is the potential of these systems than those in the field of Small Hydro- Power. We know of a large number of other new projects of the same type as these, among them the CIMPOR project, with its total close on 9MW, For theses projects, no authorisation for electrical installations was necessary and they therefore do not figure in this survey. II.2) REGULATIONS FOR THE MANAGEMENT OF ENERGY CONSUMPTION This legislation dates from 1982, altough it only reached the statute books in 1987. Its objective was to lay down the structures for operations which will hopefully be undertaken by the major electrical energy producers, in the sense of rationalising consumption and bringing about a progressive drop in energy use. This legislation, which covers all sectors, is based on two ideas: one, that the energy problems of the country will not just go away; and two, that the entitles involved are not just the State and those on the supply side. Major consumers must also bear the responsability of bringing about a dowturn in consuption and a diversification of sources. Seen from this angle, there are 106 rationalisation plans which have been submitted for approval to the Office of the Director General of Energy. The period of validity for these schemes is 5 years, from the total, 33 have already been approved and 15 were considered inadequate in terms of the targets established. After 5 years of use, these 33 will bring out an annual saving of at least 30,000 tons equivalent of oil, i.e. Esc. 675m in foreign exchange. The approach of the Secretary of State is not bound by the mere wording of the regulations. It is rather to awake the spirit of collaboration among those who run the companies in the sector, since they are the ones who will benefit first and foremost from the new procedures for management of energy deriving from the legislation. The fact that applicants for state aid must fulfil the regulations has also helped to spread on them regulations. It has been recognised that the greatest possible cost control should be exercised over investment and development plans in the energy field. For this reason, the costs of auditing can be in part offset by

A POLICY OF ENERGY EFFICIENCY

13

subsidies from SIURE, as long as methods and content correspond to the models prepared by the Office of the Director General of Energy. In this field, as has already been noted, there have been 25 applications to SIURE. As an immediate consequence of the enrgy audits undertaken, SIURE is in a position to support further studies relating to the creation and implementation of measuring systems, the recording and cost control of consumption and the infrastructures necessary for the management of energy in premises where it is consumed. This control exists as a parallel to the managemment of production, raw materials and personnel. II.3) REGULATIONS ON THE THERMAL PROPERTIES OF BUILDINGS This legislation is still at the review stage, and is in the hands of various Ministries involved. The legislation represents the first step towards standardisation of the regulations for buildings with the aim both of lowering the heating and cooling requirements and of improving the quality of the environment. With this in mind, are plans for cheking the minimal thermal characteritics of office and residential buildings and the other passive systems used their construction. As a first approach, using simple, easily understood and easily applied calculations, a start is to be made on improving buildings which have a life span of 20–30 years. The reason for this is to avoid mortgaging the future of energy. These regulations, which should be on the statute books from January 1991, draw in their train further regulations on the characteristics and dimensioning of active systems of air conditioning in the same buildings. These regulations are being drawn up in the Council of Public Works, Transport and Communications. The great challenge now is to get them known among owners, designers and builders, and also in the training of teams in Local Authorities, who will oversee and approve the regulations. III) FINANCING BY THIRD PARTIES The projects for rational use of energy require consistent technical and financial support based on turnkey principles and to this and the Office of the Secretary of State of Energy is actively promoting the creation in Portugal of service companies which provide what is known as “financing by third parties”. At this point in time there are at least 4 Portuguese companies of thie type operating in the market or in the process of setting up. A system of finance specifically for projects which generate energy savings is different from leasing operations, from credit operations involving suppliers of equipment and from other forms of finance. The fundamental differences are threefold: . The contract is specific to the supply of a consultancy service and technical assistance, a financial package for the total investment and the guarantee of concrete results; . The financing entity takes responsability not only for turning the project into a reality but also for operating the system on site for the duration of the contract; . The investment, along with associated services and charges, is paid off through the measurement of energy saved, taking the initial situation as a point of departure. The return is normally within the parameters of the savings achivied.

14

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Altough there are no public funds for this, the Office of the Secretary of State, along with the European Commission, is actively seeking the structure and support mechanisms for this system of financing. To this end, these groups can apply for support through SIURE, and it is hoped, through the VALOREN programme. At this time, ways of channelling venture capital available through PEDIP are also being actively sought for this type of company. This then is the situation regarding the major instruments created by the Office of the Secretary of State for Energy with a view to improvements in energy efficiency. And over and above this attempt to show the country what is happening—as well as the European Community represented here—I wished to take advantage of the fact that CIMPOR is also tied in with events. If there was a “Portuguese Nobel prize for energy savings” it should be awarded, in our opinion, to CIMPOR. This company realised at a very stage that is needed to manage its energy consumption efficiently, and to this has: a) diversified its energy sources by using old tyres and even coal (which was then made available for other consumers); b) recovered thermal effluents from furnaces, not only in absorption systems for air conditioning but also recovery boilers where electricity is now generated; c) exercised systematic control over consumption; and d) made savings in electrical energy through management of overheads and control of heavy electrical equipment used for ventilation and crushing. CIMPOR now has a body of knowledge and experience in these matters which I am sure would ne made available to other companies and other countries. Moreover, the company has used in the best possible way the domestic and community financial instruments available to it. If you will forgive the play on words, I should like to end by expressing my heartfelt wish that the same spirit should become a concrete reality in other companies and consumers in Portugal. By the same token I hope that the work begun today will be crowned with success.

FIRST SESSION Chairman: Professor Veiga Simao, President of LNETI

ENERGY SAVING AND ENVIRONMENTAL IMPACT IN THE CEMENT INDUSTRY ANGELO SCARES GOMES CIMPOR, Cimentos de Portugal, Portugal

Summary Since 1986 CIMPOR’s Maceira cement plant has had a tyre burning installation working regularly in two dry-process kilns, each with a capacity of clinker production of 1350 ton/day. The amount of tyres consumed per year could be doubled, at least, but the factory is now facing many obstacles in the acquisition of used tyres, due to the lack of appropriate legislation and mechanisms. The low amount of tyres burned is the main cause of the present reduced economic profitability of the installation. 1. INTRODUCTION The subject of this address has been deliberately requested within the context of the general outline conceived in the initial stages of organisation of this Seminar. The concern to include this subject in the programme is understandable. Currently questions related to the environment are of great importance, and they are not separate from the problems involved in energy saving. It is an incontestable fact that the greatest contribution of the cement industry to the improvement of the environment has always been, and still remains, the resolution of the problems raised in the industry itself. The great progress recorded in this matter over the past 20 or 30 years is also incontestable. So, for the cement industry the use of derivatives from other industries or activities is a question of relative importance, but it is still one more contribution on behalf of the environment. This utilization, which has been common practice for several years, has been even further increased in recent years as a result of the 1973 and 1978 oil crises.

ENERGY SAVING AND ENVIRONMENTAL IMPACT

17

For this reason we now propose to meet the request that has been made by presenting below some considerations on this subject, starting with the recent experience of a tyre burning installation at CIMPOR’s Maceira cement plant. In the course of several years of work it has become apparent that in various sectors the ability of the cement industry to absorb certain waste which would affect the environment or demand considerable costs to be eliminated has been regarded with extreme optimism and in too simplistic a way. What we intend to point out is that this ability is far more limited than is sometimes thought, and it always presents great economic and technical difficulties. 2. TYRE BURNING INSTALLATION AT MACEIRA CEMENT PLANT The tyre burning installation has been erected at our Maceira cement plant. This factory has two similar dryprocess kilns, with a four stage cyclone tower, each with a capacity of 1350 ton/day. In 1982 studies regarding the erection of this installation began. At that time the experience already in existence in Europe indicated the possibility of consumption of used tyres in the kilns in the near future at 15% of the total thermal energy, which meant a consumption of between 7500 and 8000 tons per year, in each kiln. It was foreseen that a sufficient quantity of used tyres would be available to use regularly with one kiln and that eventually the burning of tyres would be extended to the second kiln. This was based on the fact that the quantity of tyres produced in Portugal was calculated at about 20000 t, with an upward trend. In economic terms, the scenario envisaged at the date that the decision was made (1984) was as follows: Coal price (at factory prices) Tyre cost (at factory prices) Annual Saving (Gross) Installation Costs Payback

9760 Esc/ton 5000 Esc/ton 30 million Esc 90 million Esc 3 years

So from the economic point of view the investment appeared quite interesting. The decision for its accomplishment was taken in 1984. Basically, the installation comprises: – – – – – – – –

a tyre park where tyres are stored; 43 m reception metallic hopper, tyres supplied by a load shovel; horizontal belt conveyor; tyre elevator, 26 m high; belt conveyor with deflector for kilns Nos. 5 and 6; roller conveyor with incorporated weighing station, which feeds the tyres into the kiln; pendular double trapdoors pneumatically driven, which limit the admission of air into the kiln.

The installation became operational at the end of 1986. Following the start-up and adjustment period, normal work practice was established.

18

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

The factory has now been working for two and a half years, regularly burning used tyres in kiln No. 5. The quantity of tyres burned corresponds to 13% of the total thermal consumption in long periods of stable work, although the annual average is slightly lower at 10%. The kiln has a stable working pattern and the quality and daily clinker production have not been affected at all. The problems reported are as follows: – Thermal consumption is slightly aggravated, at a level of approximately 18 Kcal/kg of clinker (about 2%). – A greater degree of corrosion than is normal has occurred inside the gas conditioning tower, as a consequence of the presence of SO2 and NOx in the outlet gases from the cyclone tower. 3. ECONOMIC OUTLOOK During 1988 kiln No. 5 produced 395748 tons of clinker and burned 57893 tons of coal, 118 tons of fuel-oil and 5848 tons of tyres. TABLE 1. Tyre burning economic situation Clinker output Thermal ton consumption kcal/kg

COAL

Cost ×1000 Esc/ton

Consumption ton

Cost ×1000 Esc/ton

Consumption ton

1984 100% COAL Forecast (based 1984) COAL & TYRES 1988 REAL FIGURES

392300

825

400000

825

9.76 (1) 9.76 (1)

395748

843

7.98 (2)

TYRES

Operating profit Payback ×1000 Esc

51000

–

–

–

–

45200

5.0 (1)

7000

30000

3 years

52091

6.69 5848 (2)

2 280

38 years

(1) Factory price (2) Cost at loading into the furnace

Table 1 summarizes the economic analysis of the present working year, comparing it with the provisional estimations made in 1984. It can be seen that in 1988 the annual profit resulting from tyre burning was below the level forecast in 1984, and did not allow recovery of the investment. What is the reason for such a drastic reduction of profit? It is basically due to the following factors. – The significant reduction of the quantity of tyres burned each year compared to the expected level. Instead of 7500 to 8000 tons per year, or even 15000 tons if tyres were burned in both kilns, the factory burned only 5848 tons, due to lack of supply of tyres. – Increase in the thermal consumption of 18 Kcal/kg of clinker.

ENERGY SAVING AND ENVIRONMENTAL IMPACT

19

– Reduction of the coal price in the international market. The priority now must be to secure the supply of tyres to the factory. 4. TYRE COLLECTING The collecting of tyres in our country is being made by a few small road transport companies. CIMPOR negotiates with those companies a certain price for the acquisition of tyres, delivered to the factory, as well as the quantities required. Unfortunately, those quantities are never achieved. It is impossible to find such an enormous quantity of tyres concentrated in one place. Tyres are scattered widely by geographical location and are available from companies and organisations, thus making collection difficult, slow and inevitably inefficient. However, a curious situation is now happening. Some of the organisations that until recently gave the tyres freely are now demanding to be paid for the same tyres. The factory’s demand itself has led to the attribution of a certain commercial value to a product that before had absolutely no value. In practical terms this development is gradually reducing the quantities of tyres likely to be collected. As has been shown, the economics of the installation do not allow for an increase in the cost of acquisition of the tyres, but even if it were possible to pay the suppliers, it is still doubtful whether, in the medium term, the quantities would increase. Probably it would only cause an increase of the prices at the origin. So far, CIMPOR has not been able to acquire the necessary quantities to achieve viability of the installation, nor has the country been able effectively to reduce the pollution caused by the old tyres. The problem is that we are only burning 15% or 20% of the tyres produced in the country every year. It is quite clear that although the interests of the country and those of CIMPOR are identical in this matter, the desired result will only be accomplished if the state takes part, through the Central Administration, or Autarchys, regarding the concentration of the tyres in specific places. The economics of the process can support, at least partially, the cost of the transport. However it cannot bear the costs involved in the complex organization of collection of the tyres which are spread all over the country.

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY A.SCHEUER and S.SPRUNG Forschungs institut der Zementindustrie, Tannenstraße 2, 4000 Düsseldorf 30 Federal Republic of Germany

Summary Through the construction of advanced rotary kilns and the shutting down of old kilns the fuel consumption in the Federal Republic fell from 4.8 GJ/t of cement in 1960 to 3.0 GJ/t of cement in 1988. To a limited extent, energy savings are today possible by the use of secondary constituents in cement grinding or by optimizing the process technology in the preheating, burning and cooling of the cement clinker. The technological possibilities for waste heat utilization, on the other hand, are already largely exhausted. Sophisticated process technology should therefore aim at a reduction in the heat loss through the kiln wall, e. g. by the construction of short rotary kilns with tertiary air duct and precalciner. Due to increased automation and measures for an improved environmental protection the electrical energy consumption rose from 0.32 GJ/t of cement in 1960 to 0.42 GJ/t of cement in 1988. When modern roll mills are used energy savings of up to 50 % are conceivable in the grinding of the raw materials and of up to 35 % in the grinding of cement. Further savings are possible with the modern cyclone air separator, the vertical impact crusher, the optimum design of electrical drives as well as a sophisticated energy management. 1. INTRODUCTION The manufacture of cement is very energy-intensive. Already in the past great efforts have therefore been made to lower the energy consumption in the manufacture of cement (1). By using advanced rotary kilns and shutting down older kilns the fuel consumption fell for instance from 4.8 GJ/t of cement in 1960 to 3.0 GJ/t

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY

21

of cement in 1988. Due to a greater degree of automation and measures to improve environmental protection the demand for electrical energy, on the other hand, rose from 0.32 GJ/t of cement to 0.42 GJ/t of cement (s. table 1). Table 1: Cement production and average energy requirement of the cement industry in the FRG from 1960 to 1988, (Source: Bundesverband der Deutschen Zementindustrie).

Cement manufacture Fuel energy requirement per ton of cement Electrical energy requirement per ton of cement

Unit

1960

1970

1980

1988

106

24,6

37,5

33,1

24,4

GJ/t

4,8

3,8

3,4

3,0

GJ/t

0,32

0,34

0,39

0,42

t

The most important process stages where energy savings are constantly sought are a) the preparation (combined drying and milling) of the raw material components, b) the burning of the kiln feed to cement clinker and c) the preparation (milling) of the clinker to cement. Under the headings a) energy savings through product innovation b) energy savings through process optimization and c) energy savings through waste heat utilization are discussed the possibilities the German cement industry either already exploited in the past or may still have at its disposal to fulfil the demand for an optimum use of energy, a demand which is, after all, of the greatest importance to the economics of both the individual business and the national economy as a whole. However, the realization of measures should not only be judged on whether these are technologically feasible or not. Decisive are also cost considerations in relation to the results achieved. Furthermore, in future greater care has to be taken to ensure that a branch of industry is not put under cost pressure by governmental regulations impairing its competitive power on the European as well as the non-European market. 2. ENERGY SAVINGS THROUGH PRODUCT INNOVATION Portland cement is produced by intergrinding cement clinker and about 5 % of gypsum. Already since the turn of the century portland-slag cement and blastfurnace cement have existed as further standardized types of cement containing as a third component 6 to 35 % or 36 to 80 % of glasslike set and latent hydraulic granulated blastfurnace slag. Nowadays also limestone and flyash are used as constituents for manufacturing portland composite, portland filler and port land flyash cements. In addition, in the Federal Republic of Germany oil-shale and portland pozzolana cements have been made for some time. But table 2 shows that in 1988 owing to market demands portland cement still accounted for 71.7 % of the total production. Only 28.3 % of the cements contained other main constituents besides clinker. Altogether for this about 4 Mio. tons of secondary constituents were needed. In principle, the use of secondary constituents

22

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

instead of clinker brings about significant savings in fuel energy as well as electrical energy in the clinker production. On the other hand, cements with secondary constituents have to be ground to a greater fineness than a portland cement of the same strength class. Furthermore, the secondary constituents must be dried and additional transportation costs are incurred, in turn lowering the energy savings. It also has to be borne in mind that the market demands on the utility properties of the cements and an increased quality awareness regarding durability of concrete do not allow an unlimited use of secondary constituents and added materials in the manufacture of cement and concrete. Table 2: Cement type percentage of total sales on the home market in 1988. Portland cement Portland-slag cement Blastfurnace cement Oil-shale cement Portland-pozzolana cement Other cements

71,7 % 7,3 % 15,4 % 1,7 % 0,5 % 3,4 %

3. ENERGY SAVINGS THROUGH PROCESS OPTIMIZATION Fuel energy savings The major part of the fuel energy consumption is used up for the burning of the cement clinker, which in the Federal Republic of Germany is mainly produced in three types of kilns, namely a) kilns with cyclone preheater and grate cooler (type A) b) kilns with cyclone preheater and counter-current cooler (type B) c) kilns with grate preheater and grate cooler (type C). Of type A are at present 32 plants in operation, of type B 11 and of type C 22. Merely 6 plants of type A or B are equipped with a calcinator, 3 in addition with a tertiary air duct. The average throughput of the various kiln types ranges from 1,000 to 3,050 t/d, that of the individual kilns even from 500 to 3,800 t/d. This especially results in different specific heat losses through the wall of the rotary kiln, but also of the cooler and the preheater and thus in the total also in different mean specific fuel energy consumptions (s. table 3). Table 3: Average energy expenditures of cement kilns operated in the FRG. Preheater type

Cyclone

Cyclone

Grate

Cooler type

Grate

Counter-flow

Grate

Mean capacity in t/d

1700

3050

1000

Energy loss in kJ/kg cli Rotary kiln Cooler

400 500

315 500

500 500

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY

Preheater type

Cyclone

Cyclone

Grate

Cooler type

Grate

Counter-flow

Grate

Mean capacity in t/d

1700

3050

1000

Preheater Theor. heat requirement Total heat requirement

875 1760 3535

855 1760 3430

350 2220 3570

23

Table 4 shows how the fuel energy consumption of a rotary kiln with cyclone preheater increases or decreases with the source of the energy loss becoming bigger or smaller. Accordingly, a waste gas enthalpy loss of the preheater rising by 10 kJ/kg cli must be compensated with approximately 8 to 9 kJ/kg cli of fuel energy. Heat losses through the wall of the preheater affect the fuel energy consumption less and require only 0.2 to 0.8 times the fuel energy. In contrast, losses of heat through the wall in the burning zone (the lowest stage of the preheater and the Table 4: Relative alteration in the fuel energy consumption when different sources of energy loss are influenced. Eloss Waste gas energy loss Energy loss through wall of cyclone stage 2 3 4 Energy loss through wall of rotary kiln and theor. heat requirement Energy loss of the cooler

1

0,87 0.22

0,44 0,76 1.18 1,18 1,46

rotary kiln) have to be compensated with about 1.2 times the fuel energy. This factor is also to be used for assessing altered reaction enthalpies of the clinker. However, with the usual design of the kiln the greatest influence on the fuel energy consumption is exerted by the cooler. In relation, a change in the cooler energy loss leads to a change in the fuel energy consumption by almost 1.5 times (2). Thus, heat recovery in the cooler is the most important parameter for fuel energy consumption. For this reason, most optimization measures are nowadays directed towards the clinker cooler. Clinker cooler Since all rotary kilns in the Federal Republic of Germany are fed with fuel via silos or tanks, the percentage of primary air in the total combustion air is normally smaller than 10 %. Measures to improve heat recovery in the clinker cooler therefore aim at a further drop in the primary air proportion to about 5 % with at the same time low NOx emissions through the use of advanced rotary kiln burners as well as at lowering the proportion of the false air through the installation of sophisticated kiln seals. In grate coolers heat transfer may be further improved by a higher clinker bed in the recuperation zone, e.g. by narrowing the grate width or by lowering the number of thrusts. Furthermore, heat transfer may also be improved by grate plates with horizontal air outlet. If there is a chance to use the enthalpy of the cooler waste air, the design of the cooler should be such that recuperation zone and cooling zone are separated and each zone is optimized

24

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 1: Related heat loss through the wall of rotary kilns in dependence on the clinker capacity of the kiln plant for kilns with and without tertiary air duct.

individually. On the other hand, with coarse clinker or clinker with a wide grain size distribution the optimization of tube coolers or planetary coolers still presents difficulties. Cooler optimization is at present carried out in practically all plants, normally with the aim of achieving cooler efficiency rates of 70 %. Rotary kiln Especially in smaller capacity kilns heat losses through the wall of the rotary kiln may constitute a substantial proportion of the total energy losses. Accordingly, to compensate the heat losses through the wall of rotary kilns different proportions of fuel energy are needed. Due to higher energy inlet, high heat loss through the wall therefore also leads to higher waste gas energy loss of the kiln (2). An increase in the energy loss through the wall of the rotary kiln must therefore be compensated by an overproportionally high amount of fuel energy. Heat loss through the wall of the rotary kiln is mainly governed by the kiln design and its specific burning process. Fig. 1 (2) gives the heat losses through the wall of various kilns found in field tests in dependence on their clinker throughput. The figure illustrates that kilns with large clinker throughputs show smaller specific heat losses through the wall than kilns of smaller capacity. These heat losses are also smaller in kilns with tertiary air duct than in those without tertiary air duct, since in the former the operation process allows substantially smaller dimensions. Thus figure 1 makes it quite plain that by shutting down smaller kiln units and/or by installing sophisticated pre-calcination kilns savings in fuel energy may be achieved. The shutting down of smaller kilns makes especially in those cases economical sense where through this the capacity of already existing bigger plants can be better utilized. Preheater The operational behaviour of cement kilns is also determined by the cyclone preheater, in which part of the waste gas enthalpy is transferred to the kiln feed and thus recovered for the process. In addition to the gas mass flow, which in turn is governed by the fuel energy demand as well as by the air rate, the efficiency of the preheater is mainly dependent on the dust cycles in the preheater. It is normally between 50 to 65 % and may be markedly increased by the installation of additional dip tubes. Fig. 2 (2) indicates that by increasing the separation efficiency of both lower cyclone stages from 60 to 80 % each, the preheater energy loss may be cut by about 0.15 MJ/kg of clinker. In the past the installation of dip tubes was successfully effected in numerous plants.

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY

25

Fig. 2: Energy loss of a cyclone preheater with four cyclone stages in dependence on the separation efficiency of both lower cyclones.

Savings in electrical energy The main part of the electrical energy requirements is accounted for by the milling of the cement (3), in addition, the preparation of the raw materials and the burning of the clinker are also of importance (s. table 5). Table 5: Mass-related electrical energy requirement for the production of cement in the FRG. (Source: Bundesverband der Deutschen Zementindustrie). Energy requirement in kWh/t Raw material preparation Clinker burning Cement grinding Other

10 to 30 15 to 25 30 to 80 <5

Switching to advanced grinding methods The energy demand in roller mills is less than in ball mills. In this type of mill size reduction is mainly done by compression of the mill feed. In this way friction losses, occurring in ball mills under combined impact, compression and friction size reduction, are diminished. Furthermore, in roller mills substantial amounts of waste gas may be utilized for the preparation of the raw material. This is the reason why this size reduction method is above all successful in the mill drying of raw material and coal. As compared with ball mills,

26

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 3: Energy input of various mills as a function of specific surface area of the portland cements produced.

roller mills may achieve up to 50 % of energy savings for the mill drying of raw material. For the milling of cement the situation is similar, although here the energy savings are reduced with increasing wear and may even turn into an excess energy consumption. In addition, special measures are needed to safeguard the utility properties of the cement, which may also diminish the energy savings. The high-pressure grinding rolls now offer a further chance to save energy, especially in cement grinding. So far three procedures have mainly been tested, a) Pre-grinding in high-pressure grinding rolls. b) Hybrid grinding (partial or complete return of the oversize material after ball mill to the high-pressure grinding rolls and fine grinding in a ball mill). c) Grinding cycle with high-pressure grinding rolls and open-circuit ball mill placed behind. By comparison with an optimized closed-circuit with ball mill, the mere pre-grinding may lead to some 10 % and the hybrid grinding to some 20 % of savings in electrical energy (4). With the same cement properties (water demand) energy savings of up to 35 % are possible in a high-pressure grinding cycle with open-circuit ball mill placed behind. However, for quality reasons a secondary grinding in a ball mill by some 1,500 cm2/g is nowadays still necessary (5). Fig. 3 shows the energy demand of the grinding methods mentioned in dependence on the specific surface area (5). The dashed lines relate to the secondary grinding in a ball mill of grinding feed from highpressure grinding rolls operated in closed-circuit. The figure indicates that to grind cement to a fineness of some 2,000 cm2/g in high-pressure grinding rolls an energy demand of only some 9 kWh/t of cement would be needed. A secondary grinding by about 1,500 cm2/g requires additionally 18 kWh/t of cement. The total energy consumption for a grinding to 3,500 cm2/g would thus amount to about 27 kWh/t of cement. For a corresponding grinding in a hybrid mill roughly the same energy is required. However, the placing of a ball mill behind a high-pressure grinding roll cycle could lead to higher savings in energy, provided the utility properties of the cement allow a higher fine grinding in the high-pressure roll mill and thus a lower secondary grinding in the ball mill. From this follows that a separate operation of high-pressure grinding roll mill and ball mill would be best to ensure quality optimization and a reduction in the energy consumption. However, further investigations are still necessary. A further possibility for the pre-grinding of the clinker is offered by the vertical impact crusher, also known as David crusher, in which the mill feed is autogenously crushed. As against a non-optimized grinding plant with ball mill, energy savings of 14 and 24 % were achieved (6).

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY

27

Installation of advanced separators A separator in a mill system serves to relieve the mill of already finely ground cement proportions. The related result in energy savings is the higher, the more accurately the separator divides the not yet fully ground feed in fine and coarse portions. The optimization of the separator has led from the traditional rotary air separator via the conventional cyclone air separator to the cyclone air separator with specially developed circumferential screens. By replacing the rotary air separator with the modern cyclone air separator with circumferential screens and a simultaneous optimization of the ball mill 14 to 28 % of the total energy consumption needed by the whole grinding plant may be saved (7). Naturally, when considering these figures, not only the exchange of the separator has to be taken into account, but also the optimization of the ball mill. Furthermore, energy savings are only permissible so long as the cement quality is not lowered. Modification of cyclone preheaters Between 1960 and 1970 the capacity of numerous kilns was greatly enhanced without adjusting the cyclone preheater to the higher waste gas volume flows. This caused the pressure losses in the cyclone preheater and thus the specific electrical energy requirements of the ID-fan in some cases to double or to increase even more. In redevelopment work the gas cross sections were sometimes enlarged by 100 % and in addition the pressure losses could be reduced by aerodynamically adjusted geometries. In some cases the specific energy requirements of the entire kiln could be reduced by up to 15 %. 4. ENERGY SAVINGS THROUGH WASTE HEAT UTILIZATION In the German cement industry the generation of steam and current with waste heat boilers had a long tradition. Up to the 1950s and in some cases even the 1970s especially designed generators were in operation. For economical reasons the shift to the energy-conserving rotary kiln with preheater brought the use of the waste heat boiler to an end. Today their use is only profitable with clinker throughputs of 5,000 t/ d or more and low raw material moisture rates. This is due to the fact that with waste gas temperatures of 350 ºC only about 18 % of the decoupled heat flow may be recovered in the form of electrical energy and thus a high waste gas volume must be available. In the Federal Republic of Germany unused waste heat is only in a small number of kilns available, as since the introduction of the rotary kiln with cyclone preheater is has been the state of the art to use in this kiln system the waste gas after preheater to dry the raw material, the granulated blast-furnace slag and the coal. Moreover, in many cases the kiln feed is already heated in the mill to about 80 ºC. Since in the Federal Republic of Germany the raw material moisture rates are comparatively high (in some cases up to 20 %) the waste gas temperature on leaving the mill drying is frequently as low as about 100 ºC. Due to this the waste heat utilization rate is markedly higher than the generation of steam and current would allow. The few kilns with higher waste gas temperatures were equipped in recent years with one or two additional cyclone stages. Through this the fuel energy requirements of the kiln diminished substantially, the demand for electrical energy rose slightly and the waste gas temperature fell to around 100 ºC. The technological possibilities for waste heat utilization are thus already largely exhausted.

28

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

5. OUTLOOK Advanced process technology should in future aim at reducing heat losses through the wall of the kiln, e.g. by constructing short rotary kilns. According to the present state of the art a utilization of radiation losses with high-efficiency collectors is unprofitable (8). Futher energy conserving potentials are offered by an optimized design of electric drive units and networks as well as a sophisticated energy management. Thus for speed-variable working engines, e.g. ventilators, the adjustment to characteristic curves may be improved by controllable drives. In addition, with the use of the pulse generators in the installation and redevelopment of electrofilters savings in electrical energy of up to 50 % may be achieved. An indirect energy conservation is also effected with an increased use of current from power plants with favourable efficiency rates during off-peak hours. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8)

Energiepolitische Praxis in der Steine-und Erden-Industrie. Bundesverband Steine Erden e. V., Frankfurt am Main 1987. ROSEMANN, H.: Theoretische und betriebliche Untersuchungen zum Brennstoffenergieverbrauch von Zementdrehofenanlagen mit Vorcalcinierung. Schriftenreihe der Zementindustrie 48 (1987). KUHLMANN, K.: Verbesserung der Energieausnutzung beim Mahlen von Zement. Schriftenreihe der Zementindustrie 44 (1985). SCHNEIDER, G., G.GUDAT and V.SCHNEIDER: Betriebserfahrungen mit Gutbett-Walzenmühlen bei der Zementmah lung. Zement-Kalk-Gips 42 (1989) No. 4, p. 175–178. ROSEMANN, H., O.HOCHDAHL, H.-G.ELLERBROCK and W.RICHARTZ: Untersuchungen zum Einsatz einer Gutbettwalzenmühle zur Feinmahlung von Zement. Zement-Kalk-Gips 42 (1989) No. 4, p. 165–169. BINN, F.J., and W.BEESE: Einsatz eines Prallbrechers zur Vorzerkleinerung von Zementausgangsstoffen. Zement-Kalk-Gips 42 (1989) No. 4, p. 170–174. MÄLZIG, G., and B.THIER: Zerkleinern und Homogenisieren. Verfahrenstechnik der Zementherstellung. Verein Deutscher Zementwerke e. V., Düsseldorf 1987. HOCHDAHL, O.: Brennstoffe und Wärmewirtschaft. Verfahrenstechnik der Zementherstellung. Verein Deutscher Zementwerke, Düsseldorf 1987.

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY JESUS GARCIA DEL VALLE AND ALEJANDRO TORRES ASLAND TECNOLOGIA, S.A. P de la Castellana, 184, 7 28046 Madrid, SPAIN

Summary The poor economic performance of Latin America during the last decade and the high level of debt is restraining the development. The Cement Industry Outlook in Latin America is uncertain. The financial crisis caused a drop in cement consumption during the period 1981– 1984. A slight recovery has been experienced from 1985–1988, but 1989 showed a new stagnation. Projections for year 2000 are very uncertain, depending upon the economic issues of the region. Projects for new capacity extensions will be scarce in the upcoming years unless economic troubles are overcome. Energy consumption in Latin America Cement industry varies in a wide range, according to the type of process, efficiency of installations, technology, etc. Some countries have improved energetic efficiency, but in many cases only little efforts for fuel and electricity savings have been accomplished. In spite of financial difficulties, investments to improve energy efficience are advisable, in order to reduce costs and increase production capacities. Somo issues can help in a wise manner, such as rehabilitations, process conversion, precalcination system, high efficiency separator and usage of blended cements. 1. ECONOMIC ENVIRONMENT Uncertainty is perhaps the most adequate term to define the outlook of the Latin-American Cement Industry. In fact since 1980, the year in which the region started to show the first results of the world crisis of 1975, it

30

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

seems that Latin America is not able to iniciate a reasonable period of development. The next table shows the average yearly real growth of the major countries of the region during the last decade: TABLE 1 COUNTRY

GROSS DOMESTIC PRODUCT GROWTH

TOTAL

PER CAPITA

Argentina Bolivia Brasil Chile Colombia Costa Rica Dominican R. Ecuador Guatemala Honduras Jamaica Mexico Panama Paraguay

−0.1% −1.4% 1.8% 2.8% 3.0% 1.0% 2.3% 2.5% 1.0% 2.2% −0.8% 3.2% −3.1% 3.1%

−2.0% −2.7% −0.8% 1.2% 1.0% −0.7% −0.7% −0.3% −1.5% −0.8% −1.1% −0.6% −1.8% 0.0%

GROSS DOMESTIC PRODUCT GROWTH COUNTRY

TOTAL

PER CAPITA

Peru Trinidad T. Uruguay Venezuela

−1.3% 1.5% 0.9% 0.0%

−3.7% 1.4% 0.2% −2.2%

The main reasons for such a poor performance fluctuates for the different countries, but nevertheless some of them are common to most Latin-American countries: 1. A very large debt, combined with a steady high net cost of the money. 2. The reduction of prices of basic products, and the dollar revaluation weakening the trade balance. 3. The high public deficit and inflation. 4. The low efficiency of many of the investments made, reaching a ratio of incremental investment to incremental production as high as 11. 5. The protection barriers set up by the industrial countries. These barriers are costing Latin America more than 8 billion dollars per year. 6. Exit of capitals due to artificial low exchange rates. Argentina, Mexico and Venezuela, with figures of 65, 48 and 135 respectively, as percentage of outgoing capitals over incoming capitals, are examples of it. The net result for Latin-American countries is an unbearable high level of debt, which is seriously restraining their development:

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

FIGURE N 1 GROSS DOMESTIC PRODUCT GROWTH LAST DECADE YEARLY AVERAGE

TABLE 2 COUNTRY

DEBT/GNP

Argentina Bolivia Brasil Chile Colombia Costa Rica Dominican R. Ecuador Guatemala Honduras Jamaica Mexico Panama Paraguay

60 110 30 90 40 90 70 90 30 70 120 60 70 50

31

32

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

COUNTRY

DEBT/GNP

Peru Trinidad T. Uruguay Venezuela

25 30 40 70

FIGURE N 2 LEVEL OF DEBT

2. CEMENT SECTOR. SITUATION AND FUTURE Cement production in Latin America reached about 85.2 million metric tons in 1988, that is 300,000 MT less than 1987’s figure. Apparent consumption was close to 78.9 millions, slightly under 1987’s, that reached 79 milliom, the record figure for the zone. The main exporters were Mexico (4.5 million MT), Colombia (1 million MT), and Venezuela (0.8 million MT). Most of these cement exports had U.S.A.’s ports as destination. Per capita consumption was 181 Kg., while the previous year it had been 186 KG. The per capita figure drop has been more important than the total consumption decrease due to the high population growth rate (2.4% as average).

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

33

Table n 3 presents the breakdown of these figures by regions. Regional grouping is the same as Cembureau’s, that is: CARIBBEAN: Bahamas, Barbados, Cuba, Dominican Republic, Guadeloupe, Haiti, Jamaica, Martinique, Puerto Rico, Trinidad-Tobago and other islands. CENTRAL AMERICA: Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua and Panama. SOUTH AMERICA EAST: Argentina, Brasil, French Guiana, Guyana, Paraguay, Surinam, Uruguay and Venezuela. SOUTH AMERICA WEST: Bolivia, Chile, Colombia, Ecuador and Peru. TABLE 3 CONSUMPTION REGION

PRODUCTION (Mill. MT)

TOTAL (Mill. MT)

PER CAPITA (Kg/inhab)

CARIBBEAN CENTRAL AMERICA SOUTH AMER. EAST SOUTH AMER. WEST TOTAL

7.6 25.6 38.3 13.7 85.2

7.7 21.2 37.4 12.6 78.9

231 184 183 153 181

Source: CEMENTO-HORMIGON and own investigation

The evolution of cement industry during recent years shows a steady growth up to 1980/81, when the per capita consumption reached a record (208 KG), even higher than the World average figure. (See figure n 3). From this peak, there is a sharp drop, as a result of the financial crisis, that reached the lowest level in 1984, when the consumption was only 65 million tons, that is 164 Kg. per capita. From 1985 up to 1987, there is a recovery, but 1988 represented a stagnation, perhaps a hint of a coming drop, if economic problems of the zone go on hampering the industrial activity. The drop in cement consumption during 1988 was more acute in some countries, such as Mexico (−3. 1%), Agentina (−5.4%), and Peru (−3.7%). Brasil had no growth in this year, and other countries experienced positive variations, compensating the drop of the previously mentioned. Chile (+15.4%), Venezuela (+6.8%) and Colombia (+5.3%) show the more outstanding increases. Figure n 4 presents the historic and projected consumption of cement in the zone. Projections are presented in three scenarios: – Low: It corresponds to the stagnation of total consumption (79 million MT in 2000), but it means a sharp decrease in percapita figures (135 Kg). – Medium: Intermediate assumption, reaching in 2000 a total of 119 million MT and 205 Kg. per capita. – High: In this case, cement consumption growth reasumes the pace of the period 1970–80. That means that the zone is able to overcome its economic troubles. Total consumption will be 158 million in 2000, that is 270 Kg per capita. The span between the low and high projection is really very high, but this is a consequence of the huge uncertainty we have referred to. It is not possible to narrow the gap without lossing a high degree of reliability.

PER CAPITA CEMENT CONSUMPTION (KG)

FIGURE N 3

34 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

35

The production capacity of the zone in 1987 was 122.5 million MT. We have calculated this figure using the data from the CEMBUREAU Directory, and including the expansion projects undertaken. It corresponds to the nominal cement production capacity with own clinker, considering the usual clinker/ cement ratio. It is well known that nominal capacities are not always realistic, but even taking this fact into account, the gap between present capacity and consumption is quite big, and indicates a high probability of the zone keeping its excedentary position. Projects for new capacity extensions, thus, will be predictably scarce in the coming years. They will be localized to specific countries, and only if the high scenario occurs, will they appear everywhere. 3. ENERGY CONSUMPTION We have included in our presentation this brief consideration on energy consumption aspects in the Latin American Cement Industry. As it can be seen in Table 4 and in figures 5 and 6, there is a wide range in the figures concerning energy consumption. Data in this table refer to unit consumption for the years 1987 and 1988. TABLE 4 ENERGY CONSUMPTION IN SOME COUNTRIES OF LATIN AMERICAN CEMENT INDUSTRY 1987–1988 ENERGY CONSUMPTION FUEL.Kcal/Kg.Ck

POWER. Kwh/MT.Cmt

COUNTRY

1987

1988

1987

1988

Argentina Brasil Colombia Costa Rica Cuba Dominican R. El Salvador Guatemala Honduras Peru Uruguay Venezuela

966 997 1400 855 n.a. 1165 1000 846 980 n.a. 1335 1200

1026 994 1400 855 1434 1173 975 850 1027 881 1334 1200

130 123 125 132 n.a. 127 116 116 134 n.a. 117 125

128 125 122 132 117 118 117 110 131 132 118 125

source: own investigation

As per calorific consumption is concerned, figures vary form 846 Kcal/kg of clinker in Guatemala, to 1434 Kcal/Kg. clinker in Cuba. When considering power consumption, the range goes from 110 Kwh/MT. of cement (Guatemala) to 134 kwh/MT. of cement (Honduras) The differences in calorific consumption lay mainly in the type of process. Wet or dry system process and precalcination technology are decisive on this subject. In table 5 the breakdown of kilns by types and

LATINAMERICA CEMENT CONSUMPTION

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

FIGURE N 4

36

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

37

Fig.5. Fuel consumption (Kcal/kg.Ck.)

geographical regions is presented. Data have been elaborated from basic information form 1987 World Cement Directory (CEMBUREAU). Dry column means dry and semidry processes. TABLE 5 CEMENT KILNS IN LATIN AMERICA Capacity and type of fuel N OF KILNS

Clink.Capac. (1000 MT/Year)

REGION

TOTAL

DRY

WET

PREC

TOTAL

DRY

WET

Caribbean Central America S.Amer. East S.Amer. West TOTAL % Average/kiln

49 107 193 77 426

7 90 141 38 276 65%

42 17 52 39 150 35%

0 32 14 9 55 13%

11270 34370 59010 15120 119770

4345 32190 50895 9570 97000 81% 351

6925 2180 8115 5550 22770 19% 152

REGION Caribbean Central America S.Amer. East

281 TYPE OF FUEL (%) Coal Oil 19 76 0 69 26 49

Gas 4 31 24

Other 0 0 0

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Capacity and type of fuel N OF KILNS

Clink.Capac. (1000 MT/Year)

REGION

TOTAL

DRY

WET

PREC

S.Amer. West TOTAL

47 21

36 56

16 23

0 0

TOTAL

DRY

WET

Source: Preparation based on data from the 1987 CEMBUREAU’s “World Cement Directory.

Fig. 6. Power consumption (Kwh/MT.Cmt.)

As it can be seen, in 1987 wet processes represented still a 35% in number of kilns and a 19% in clinker capacity. Percentage of kilns equipped with precalcinator was a bare 13%. Regional differences are remarkable. I.e., percentage of wet kilns in the Caribbean Bassin was 86%, while Central America recorded the lowest ration, with a figure of 16% in number of kilns and only 6% in clinker capacity. In this region, the percentage of precalcination kilns is also outstanding (30%). The huge effort of new investment in the Mexican cement industry in recent years should be outlined, as a cause for the mentioned differences. On the other side, in Colombia, one of the countries with high fuel consumption ratio, almost 70% of clinker capactiy corresponds to wet process kilns. The percentage is higher when dealing with production instead of capacity, as wet lines are more efficient than dry ones. In Venezuela a 40% of clinker capacity still lay in wet process, with no incentive to save fuel.

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

39

Higher number of dry process kilns has been accompanied with the increase in the average size of production lines. New lines, with modern technology, are usually bigger than older ones. As shown in next table, the average capacity was 281,000 metric tons per kiln, according to data from 1987 CEMBUREAU Directory. While the average size of wet process kilns was only 152,000 MT, the average capacity of dry process ones reahced 351,000. This has a double effect on energy consumption figures. Fist, the dry technology has a fuel saving effect. So, as acutal consumption in wet process kilns investigated varies in the range of 1300–1500 Kcal/Kg., dry process kilns only need 850–950 kilocalories per kilogramme of clinker, or even less if precalcinator technology is used. On the other side, as it is well known, the higher capacity by itself produces energy saving, concerning both fuel and power. According with the same source, in 1987 an average 56% of clinker capacity was prepared to use oil as fuel, while the corresponding percentage for coal (mineral and vegetal), and gas was 21% and 23% respectively. It was a trend from the mid 70’s the conversion of kilns from oil to coal, in order to avoid the high costs of liquid fuels derived from the petroleum crisis. But as the table shows, many countries are proved sluggish to keep pace with this trend. So, for instance, the percentage of capacity served with coal is only 19% in the Caribbean. In Central America, the percentage is negligeable. There is an explanation when dealing with Mexico, but other countries of the zone, non oil producers, are still entirely dependent on expensive oil imports. Outside coal, oil and gas, other fuels are starting to be used. The percentage of these fuels according to data form the 1987 Directory is also negligeable, but in practice the utilisation of “poor” fuels is gaining ground. So, oil palm shell, rice shell, etc, become complementary fuels favouring energy cost reduction. On the other side, power consumptions depend on other factors, such as the process technology, the efficiency of the installation, the size of the same, the types of cement produced, etc. Concerning the process technology, important efforts have been undertaken in order ot install high efficiency separators. Size of production is also very important in connection with power consumption, as it has been stated beforehand. But this is in the field of cement types where the most outstanding results can be obtained. Blended cement, using additions such as pozzolanas, fly ashes, iron slags, etc., have a favouring effect on energy consumption, both fuel and power figures. Addition utilization reduces the percentage of clinker in the production of cement. Some countries have developed the production of this type of cement, reducing the clinker/cement ratio. Table n 6 and figure 7 present some examples, the figures corresponding to 1988. TABLE 6 CLINKER/CEMENT RATIO (figures corresponding to 1988) COUNTRY

%

Argentina Brasil Colombia Costa Rica El Salvador Guatemala Honduras Uruguay

90 79 82 93 95 90 85 90

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 7. Clinker/cement ratio (figures corresponding to 1988)

Some countries show interesting ratios, as Brasil (79%), and Colombia (82%). But many other are mainly producers of Ordinary Portland Cement, type ASTM1 or similar, with clinker/cement ratio about 95%. So far, utilization of iron slags is widespread in some coutries such as Brasil or Colombia. Utilization of pyroclastic materials is becoming more and more important, with more users in Argentina, Chile, Honduras and other countries. What will the future be like in energy consumption aspects? In our opinion Latin American Cement Industry should go on the started path. Reduction of energy consumption shall be performed by process improvements and unit cement production increases. The decisions should be considered in aspects such as: – – – – –

Rehabilitations Conversion from wet to dry process Precalcination systems High efficiency separators in mill installations Increasing usage of blended cements

These issues can provide better energy efficiency and extended capacity in the existing units. Utilization of blended cements, by itself, may increase cement capacity by a 10/15%, without resorting to important

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

41

investment outlays. The other are more expensive, but also increase production capacity and may constitute profitable solutions. As we explained before, production extensions will not be needed in a general way, but in some countries experiencing deficits, new capacities through economic and rational solutions will help to avoid cement deficits in spite of financial difficulties. In other countries with cement surpluses, this type of solutions is also wise, as it can contribute to operation cost reduction, and better employment of existing facilities. A lower utilization of old lines, that have his operation costs, would also be possible.

ENERGY OUTLOOK IN THE JAPANESE CEMENT INDUSTRY YUKIO NAKAJIMA Senior managing Director NIHON Cement Co., Ltd. TOKYO JAPAN

1. PRESENT SITUATION OF JAPAN’S CEMENT INDUSTRY a) Domestic cement demand in 1988 was 78 Mton. b) Average kiln capacity per unit is 1 Mton/year. c) Classification of cement works by annual production capacity. more than

3.5 Mton/year 2.5–3.5 Mton/year 1.5–2.5 Mton/year 0.5–1.5 Mton/year

: : : : :

8% 10% 23% 51% 8%

smaller than 0.5 Mton/year d) Coal burning ratio to total fuel consumption: 100% e) Total employees at active in cement works are 7,500 men power and Labor productivity is 9,400 t/ year.man. f) Average heat consumption: 710 kcal:kg Average Power consumption: 103 kWh/t. g) Classification by type of kiln. (Ratio to total production) NSP Kiln SP Kiln the others

: : :

80% 16% 4%

ENERGY OUTLOOK IN THE JAPANESE CEMENT INDUSTRY

43

2. PROGRESS OF ENERGY SAVING UP TO THE PRESENT. a) Small and medium-scale, Low-productivity factories were closed, and production concentrated in conveniently-located large-scale factories. b) Improvement of Labor productivity and Labor saving by way of those under integration of workshops, mechanization and remote control, increasing the scale of facilities and concentrating production, were also greatly contributed to energy saving. c) Diversification of cement quality such as to blast furnace slag cement and others has had a significant effect. d) Technical measures has been employed as follows: – Selection of cheaper fuel at the times. conversion Fuel from heavy oil to coal completed very quickly for which investment in total was one hundred billion yen. – Improvement of thermal efficiency. Heat consumption was 1700 Kcal/kg in 1955; by 1988, it had decreased to less than half of that, or 710 Kcal/kg. Changing the type of Kiln process made one of significant contribution. – Reduction of electric power cost. Average power consumption was 120 kWh/t in 1978; by 1988, it had decreased to 103 kWh/t. Maximimized utilization to off peak period (night time) power, waste heat generator and development of vertical roller mill provided great power cost saving. Improvement of efficiency of finish and raw mill putting through various liners, intermediate diaphragms and wear-resistant media for tube mills also contributed to power cost reduction. – Optimization of the process. Changing from logic model system to Artificial intelligence and fuzzy logic computer control system had contributed to saving production cost in terms of high efficient plant operation. 3. OUTLOOK OF ENERGY SAVING. a) Selection/utilization of cheaper fuel. Industrial waste and waste gas from kiln and cooler at cement works as energy sources would be important. b) New development of process, facilities and materials in terms of higher efficiency and longer life should be continued. c) Optimization for scale of cement production, process control method, plant location and transport of cement should be worked out further. d) Management – Long term stable operation is a principal at plant management. To achieve this, a strong effort to stabilize quantity of raw materials, fuel and plant operating conditions must be made. – Plant breakdowns are the biggest barrier to reduction of energy consumption. Attention on the preventive maintenance is required. – Overall participation included all operators make it possible to improve plant efficiency because operators are actually at the scene and have first-hand experience in the day-to-day working of the plant.

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 1. Cement demand in Japan

Fig. 2. Capacity per kiln

4. CONCLUSION. Energy saving is eternal theme. The approach to energy conservation changes with the conditions surrounding the enterprise and the background technolgy of the times. For this reason, the international exchange of ideas and methods for energy conservation will become even more important in the future.

ENERGY OUTLOOK IN THE JAPANESE CEMENT INDUSTRY

Fig. 3. Number of cement plants classified by annual production capacity

Fig. 4. Labour productivity and number of employees

45

46

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 5. Ratio of coal-burning to total fuel consumption

ENERGY OUTLOOK IN THE JAPANESE CEMENT INDUSTRY

Fig. 6. Heat consumption and production classified by type of kiln

47

48

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 7. Power consumption

DISCUSSION

DR TOM LOWES, Blue Circle Cement, asked MR A SCHEUER. QUESTION You made no mention of the possibility of using expert systems/high level control and energy savings. ANSWER This is a good method of improving efficiency but was omitted because of time constraints. MR TANGNEY, Irish Cement, asked MR NAKAJIMA QUESTION Does the labour productivity figure indicated include contract labour? ANSWER The labour productivity does not include sub-contractors who are used to reduce the numbers directly employed. MR SAMOUILHAN, CLE France, asked MR NAKAJIMA QUESTION Regarding consumption of 700 kCal/kg, is it calculated on a clinker or cement basis and do you include additives in your calculation? ANSWER No, additives are not included. MR GONCALVES DOS SANTOS, Secretary of State for Energy, Portugal, asked MR SOARES GOMES

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

QUESTION Regarding decreased NOx output, is this due to decreased consumption in energy? ANSWER Changes introduced so far make us sufficiently confident that we can continue consuming tyres without any SO2 and NOx damage to the environment. It is true that we have noted some corrosion in the conditioning tower, which is where gases are emitted. However, this does not lead us to the conclusion that we should cease to burn tyres for environmental reasons. J F SOARES, CIMENTO CAUE SA, Brazil, asked if anyone had any experience burning urban waste. MR SOARES GOMES—We have no experience of this in Portugal. Studies were carried out ten years ago. MR K BEZANT, Blue Circle Cement—Yes, we have experience at a wet process kiln where we burned up to 15% fuel replacement using processed domestic refuse. The capital plant required to prepare the refuse is very expensive and therefore one has to be paid a very good rate by the local authority to justify the capital expenditure. Furthermore, on the wet process kiln, which was gas emission linked, there was a reduction in output of 3% to 5%, so the overall economics depend upon the requirement for using the full capacity of the kiln and also the payment from the local authority. It is therefore technically feasible but economically unlikely. MR CASTELA, CIMPOR, Maceira, Portugal—As a supplement to Mr Gomes’ contribution I would like to comment on our production centre. Burning tyres gives rise to two problems in the cyclone tower and in the conditioning tower. There is an increase in encrustations, especially sulphur clogging, and we have found within the conditioning tower that corrosion levels were higher than desirable. Measurements of SO2 and NOx content, just with coal and compared with coal plus tyres, have been taken. With coal alone the SO2 content in the exhaust fumes from the cyclone tower were around 50 mg/m3 and with tyres at around 13% of the fuel input the SO2 content doubled to 100 mg/m3. But in the conditioning tower after the circuit the SO2 levels were unchanged at 50 mg/Nm3. NO2 levels were 700–800 mg/m3 with tyres. After the conditioning tower, these figures were reduced to 900 to 1000 mg/m3. These figures are only provisional. M MAKRIS, CLE, France—I would like to give some more information about the use of grinding rolls. Mr Scheuer has explained that some investigation was still necessary to use grinding rolls without any need for a ball mill in integral grinding. Six months ago CLE developed and started up a new plant in France using the roller press without a ball mill. This plant is producing cement at a capacity of 55 tonnes/hour and the total energy consumption of the unit is 20 kWh/tonne of ground output. V TEIXEIRA LOPO—To summarise the first session, the problems of energy efficiency are eternal. I believe that new technology, new approaches and new perspectives can be derived in order that the European Community can have a sound policy for the year 2000.

SECOND SESSION PART 1—SPECIFIC TECHNOLOGIES AND CEC DEMONSTRATION PROJECTS PART 2—ENGINEERING AND ENERGY MANAGEMENT Chairman: J Sirchis, Commission of the European Communities

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT RECOVERY IN CEMENT PLANTS E.STEINBISS KHD Humboldt Wedag AG, Cologne, W-Germany

Summary Kiln exit gases and the exhaust gases from clinker coolers often cannot be fully utilized in drying plants. In such cases a part of the heat content of the gases should be utilized for water heating. In addition, it is possible to utilize the waste gas heat in conventional steam boilers, with which, depending on design, it is possible to generate electricity at a rate of between 10–35 kWh/t (net output). The feasibility of the heat recovery system will be given today only for large units above 3000 t/d clinker. A new method of utilization of waste gas heat is provided by precalcining systems with bypass, in which up to 100 per cent of the kiln exit gases can be economically bypassed and be utilized in a steam boiler, without requiring any cooling. Further raise in heat recovery efficiency could be achieved by introducing the Organic Rankine Cycles (ORC-Process). 1. INTRODUCTION Cement plant operators again and again raise the question as to what possibilities there are for utilizing the waste heat from their kilns. The question becomes particularly important in cases where the scope for the conventional (and thermally very advantageous) utilization of this heat for drying of raw material, coal or slag does not exist. The heat quantities, contained in the waste gases are relatively large and constitute the major loss items in the heat balance of the burning process. This is true also for plants where considerable

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT

53

amounts of bypass gas are extracted at the kiln inlet (feed end) because the gas temperature in this part of the system is particularly high. From the heat balance of a cement kiln with cyclone preheater and 30 % bypass in table 1 it appears that about 20–30 percent of the heat losses are due to the pre-heater waste gas and the exhaust air from the clinker cooler (1). Table 1: Average values of heat consumption for cement clinker burning heat quantity referred to clinker theoretical heat requirement waste gas heat exhaust air from cooler bypass gas heat (30 % bypass) wall heat loss (preheater, kiln, cooler) heat in clinker discharged remainder total

kJ/kg

%

1700 640 400 260 230 100 50 3380

50 19 12 8 7 3 1 100

In plants with gas bypassing the loss due to this technique may, depending on the amount of gas extracted, range up to 32 percent of overall heat consumption. It is particularly this highgrade heat that opens up fresh possibilities for its utilization. For this reason, in recent years, we have investigated how the various waste gas heat quantities can be optimally utilized in separate units. This development is further encouraged by the fact that the cost of primary fuels has been continually rising for a good many years now. The recovery of heat from waste gas in a waste heat boiler involves the combined operation of two processes, however. The drawback is that the waste heat boiler has to be shut down when- ever the kiln is stopped. This must be taken into consideration in the design and operation of the boiler. On the other hand, it should be possible to continue operating the kiln in the event of a fault or shutdown of the heat recovery system, without any adverse effects upon the burning process in the kiln. In my report I want to deal more particularly with the recovery of heat from waste gases in waste heat boilers. And I want to point out that a waste heat boiler should be considered only if there is no other possibility of utilizing the heat. 2. WASTE GAS HEAT UTILIZATION POSSIBILITIES Different amounts of exit gas or waste heat may arise from modern cement kilns equipped with cyclone preheaters. This will depend on the methods and machinery employed. Fig. 1 schematically indicates the principal points of gas discharge from the rotary kiln process with precalcination. The waste gases differ with regard to quantity, composition, temperature, pressure and dust content. It is presupposed that these gases cannot be directly utilized in the burning process. Table 2 gives guidance in assessing the utilization potential of the waste gases. This utilization potential of a waste gas flow increases more than proportionally to its temperature. Hence it will always be endeavoured preferentially to utilize those gases which are hottest. Below 100 °C it is generally no longer economically attractive to utilize the heat.

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Fig. 1: Extraction points for exit gas and exhaust air flows Table 2: Characteristic data of utilizable waste gas mass flows point of gas extraction

designation

spec, mass temperature °C underpressure flow m3/kg 1)2) mbar

dust content g/ scope for m3 1) utilization

1

preheater waste gas

0,6–1,8

280–600

20–80

20–100

2

preheater intermediate gas

0,1–0,4

500–800

30–70

50–150

3

kiln exit gas (bypass gas)

0,1–0,5

1000–1200

2–10

50–300

4

hot air from cooler (secondary air) exhaust air from cooler

0,1–0,3

700–900

0.1–0,5

5–200

0,4–1,8

150–400

0,1–0,5

5–20

5

drying of: raw material filter cake blastfurnace slag coal (inert operation) steam generation drying of: filter cake coal (inert operation) steam generation drying of: blastfurnace slag raw material 3) coal 3) steam generation drying of: filter cake drying of: raw material, coal preheating of:

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT

point of gas extraction

designation

spec, mass temperature °C underpressure flow m3/kg 1)2) mbar

55

dust content g/ scope for m3 1) utilization oil, water ORC-process steam generation

1) at standard temperature and pressure (0 ºC, 1013 mbar) , 2) referred to clinker , 3) possible only after dedusting

High dust content in the waste gases is liable to have an adverse effect because the dust gets into the material to be dried or causes deposits or incrustations in waste heat boiler systems requiring special aids and expedients for their removal. It is therefore better to dedust the gases first. Although this does cause a pressure drop, it is advantagous because the dust is collected and reclaimed, while wear and power consumption of the waste gas handling fan are reduced. The amount of heat contained in the waste gas flow is the deciding criterion with regard to the feasibility of utilization or energy recovery. The determining quantities are the mass flow rate, the temperature of the waste gas and the thermal capacity. Table 3: Heat contained in selected waste gas flows for a 1000 t/d kiln designation

preheater waste gas kiln exit gas for 100 % bypass exhaust air from cooler

without bypass

100 % bypass

temperature spec, mass flow 1) spec, therm, capacity 2) heat content 1) spec, energy output 1) thermal power output

[°C] [m3/kg] [kJ/m3·K] [kJ/kg] [kWh/t] [MW]

350 1,5 1,5 740 206 8,6

280 1,1 1,4 400 110 4,6

1250 0,45 1,7 940 262 10,9

250 1,4 1,3 420 116 4,8

1) referred to clinker. 2) at standard temperature and pressure (0 ºC, 1013 mbar)

Table 3 gives the heat amounts contained in three selected waste gas flows for a kiln with 1000 t/d clinker output. The thermal power output of the waste gas flows is indicated in the last column of the table. With reference to this it is to be noted that not all the power can be obtained simultaneously. With bypass operation the amount of waste gas discharged to the preheater is reduced. Besides, the temperature of this gas is lowered. Fig. 2 shows the relation between the heat loss in the preheater waste gas and the proportion of bypass gas diverted from the kiln inlet. In establishing this diagram the proportioning of fuel fired in the calciner was varied between 50 per cent and 65 per cent. With increasing proportioning of bypass gas the amount of waste gas from the preheater correspondingly decreases and its temperature is lowerd. The two effects bring about a more than proportional decrease in the heat loss in the waste gas. The amount and temperature of the waste gas would similarly be reduced if part of the intermediate gas from the preheater is removed from the process.

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 2: Relation between waste gas heat after pre-heater and heat content of partial gas flow divertet from kiln inlet

2.1 BYPASS GAS FROM THE KILN INLET From Table 3 it appears that when a high proportion of bypass gas is extracted from the kiln, the heat losses that this involves are of the order of magnitude of the waste gas heat losses downstream of the preheater or indeed may, if the kiln gases are completely bypassed, exceed those losses. Taking account also of the high temperature of the kiln exit gas, i.e. the high-grade heat content, it is evident that the greatest possibilities for heat recovery are offered by the hot kiln exit gases. For a plant with a clinker production of 1000 t/d and 100 per cent gas bypassing a thermal power output of more than 10 MW would be available. With the usual bypass system there is no scope for direct utilization of the heat for raw material and coal drying because this would cause the undesirable substances removed with the bypass gas to be returned to the process. The gas can be utilized for raw material drying only after its dust loading has been removed. For blastfurnace slag drying it is possible to use bypass gas (after cooling with air) or waste gas without having to dedust it. This method has been applied in a Austrian and also in a German cement plant since 1985. Gas bypassing from the inlet of the kiln may also be applied if the raw material moisture content is so high that the heat content of the preheater waste gas and that of the exhaust air from the clinker cooler together are not sufficient for drying the material. When kiln exit gas is utilized in waste heat boilers it must be considered that the gas contains about 30 g of dust per m3. This dust, and the gaseous atmosphere itself, usually contain considerable amounts of sulphur and chlorine compounds which condense on cooling and are liable to form adhering deposits on

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT

57

Fig. 3: Waste heat boiler connected to the inlet of cement kiln I or the waste gas duct of the preheater II

relatively cool wall surfaces. This gives rise to the rapid growth of hard coating which are difficult to remove. For this reason it should be checked whether the gas at 1250 °C can suitably be supplied to a heat recovery installation or whether it should first be cooled—by mixing with fresh air or with other gases or by water injection—to such an extent that the problems of coating build-up can be reliably controlled. With the object of trying out the uncooled bypass heat recovery technique KHD Humboldt Wedag, Cologne, has been engaged, jointly with the boiler engineering firm of L.C.Steinmüller, Gummersbach, in a development project in which a waste heat boiler is connected directly to the feed end housing of the kiln (2, 3). Comprehensive tests should yield information on the operating behaviour and the maximum recoverable energy. However these tests can only give reliable results if they can be achieved in a boiler which is actually connected to a cement kiln. This will rise high costs which can not only be borne by a research and development budget but must be financially supported by an actual project of a cement manufacturer. Unfortunately there was no possibility up to now for the realisation of a bypass waste heat boiler. This is due to the location of all the plants with a high bypass rate, i.e. Egypt or Iraq, where the fuel costs are so low that the application of this technique will not be feasible. The arrangement of such a boiler in an existing plant is represented as version I in Fig. 3. A major consideration in the design of such equipment is the possibility of proper cleaning, e.g. with pneumatic rapping devices, and the removal of dust and dislodged coating. It is to be noted that in a two-pass boiler the dusts from the two passes are different and can be separately removed.

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

In this arrangement, the bypass gas could be utilized in the boiler down to 200 °C. Or it is utilized in the boiler only down to 350 °C and can then be further utilized for material drying. The boiler volume would thus be substantially reduced and it might, under certain circumstances, be possible to do without gas dedusting. Another possibility for using the heat of the bypass gases is the aplication of Ahlströms Fluxflow technology (11). Fluxflow represents a system where the bypass gases are quenched in a circulating fluidbed for combined heat recovery and gas cleaning. The heat is recovered as hot water or steam by indirect heat exchange. Due to the quenching of incoming gases in the circulating fluid bed the vaporized alkalis condensate on the surface of the fluid bed material. Even submicron alkali fumes are largely avoided. So the removal of alkali components and dust can be achieved in excess of 90 % with cyclones only. The precleaned bypass gas has a temperature of about 200 °C, has a much smaller gas volume compared to an air cooled bypass and can be dedusted in the electric pre-cipitator of the cement kiln. As fluid bed material the bypass dust itself can be used. The first industrial Fluxflow at a cement kiln in Finland is in operation since 1987 as a alkali bypass and turned out to be economical, as the hot water can be supplied to the district heating network. 2.2 WASTE GAS FROM PREHEATER The waste gas discharged from the kiln preheater likewise contains substantial amounts of heat. The output for a 1000 t/d cement plant is calculated at 8.6 MW. The gases in question have a temperature of 350 to 400 °C and a dust content of about 25 g/m3. In general, the dust is not sticky, but tends—depending on its chemical composition—to form coatings or deposits on hot surfaces. A boiler of this kind must therefore be equipped with effective cleaning devices. If the raw material moisture content is low, so that only a limited proportion of the exit gas is needed for drying, a waste heat boiler may be installed which utilizes the upper temperature range of the waste gas from 400 °C to 250 °C or 200 °C (Fig. 3, version II). From 200 °C down to about 100 °C an ORC process with organic working media instead of water could be additionally installed for electric power generation. Conventional waste heat boilers for steam operating in combination with a steam turbine and electric generator have already been installed as an integral feature in the waste gas duct directly downstream of a preheater in a number of plants (4, 5, 9, 10). In the first case in Switzerland 1981, a 1 MW (el) single-pressure boiler of vertical type was installed on top of a 4-stage preheater (Fig. 4 and 5), producing steam at 7 bar and 290 °C and causing a pressure drop of 800 mm w.g. This waste heat boiler is controlled from the cement plant’s central control room. Operation of the boiler has so far never caused interruption or reduction in cement output from the plant. Conversely, cement kiln shutdown involves shutting down the whole heat recovery system, but the latter can subsequently be restarted quite simply by pushbutton control. The electrical efficiency of the system is 17.8 percent, and specific net electricity generation amounts to 10.8 kWh/t of clinker. A pneumatically operated acoustic cleaning system (140 dBA, 200–300 Hz) for the boiler heating surfaces has been installed. It can, however, only cope with major fouling of these surfaces. A certain amount of permanent fouling under continuous operating conditions is unavoidable. In 1982 another waste heat recovery power plant was built in a Japanese cement plant for a cement kiln with preheater (Fig. 6) with a clinker production of 7500 t/d. In this case a 7 MW (el) single-pressure boiler of

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT

59

Fig. 4.: Connection of the waste heat boiler on top of a 4stage preheater

vertical type was chosen. The boiler was installed besides the preheater tower. It is a forced circulation type producing 44.7 t/h steam at 14 bar and 290 °C. The boiler is built as a bypass between the existing gas ducts, and the induced draft fans of the preheater can still be used. A modern automatic control system provides fully automated operation. The inlet gas temperature of the boiler is about 440 °C whereas the outlet gas temperature is 250 °C. As reported in Janpanese publications (5, 9) there were sixteen cement kilns already in 1987 equipped with waste heat boilers and electricity generating systems, and another four such installations are in operation or will be installed in Taiwan, South Korea and Thailand. The main reasons for having built so many systems in Japan are the assistence of the Japanese government in terms of tax and in most cases considerably high preheater waste gas temperatures or additional firing devices for direct steam superheating. 2.3 EXHAUST AIR FROM COOLER With grate coolers a considerable amount of exhaust air is obtained which in general has to be dedusted. Because of the particular operating conditions in a grate cooler, considerable temperature fluctuations in the range of 150–400 °C must be expected. Also, the dust loading of the air may vary greatly, depending on the granulemetric characteristics of the clinker. For special utilization purposes the exhaust air can be extracted from the cooler at two different points and thus be divided into a colder and a hotter portion. The hotter portion is thereby thermally upgraded; its temperature is about 250–350 °C.

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 5.: Heat recovery system

In former years the exhaust air from clinker coolers was occasionally used for heating water or heat transfer oil (thermal oil) or for drying purposes. The experience gained with such utilization shows that hardly any wear due to clinker dust occurs in heat exchanger equipment receiving the exhaust air (7) . The thermal effectiveness can therefore be safely increased without first dedusting the heat transfer medium. This offers the added advantage that the dust collector installed downstream of the heat exchanger has to handle a smaller volume of gas and can therefore be more compactly dimensioned. The heat content of the exhaust air discharged from the clinker cooler can, as already stated, also be used for steam raising. The temperature range from 250 °C to 150 °C could be utilized for this purpose, followed by a second stage of utilization incorporating on ORC process in which the air temperatur is further lowered to 70 °C. This low temperature is attainable with exhaust air because it is still sufficiently far above the dewpoint. With a 1000 t/d cement kiln it would, with this process, be possible to obtain about 0.6 MW (el) in the first stage and about 0.3 MW (el) in the second stage (8). Until today the ORC process has not been applied in the cement industry. But the steam process is used in several cases already to recover the heat in the cooler exhaust air. This is also done in combination with a preheater waste heat boiler by applying the “double path method”. Fig. 7 shows the flow diagramm for the utilization of waste gas from two sets each of kiln preheater and air quenching cooler. This power plant has a rating of 11.1 MW and has been built in a Janpanese cement plant which is operating one cement kiln with a clincer capacity of 5000 t/d and one with 4000 t/d. The turbine is a mixed-pressure reaction and condensing type and operates with a main steam pressure of 49 bar. The mixed steam pressure is 1.0 bar. The corresponding steam temperatures are 400 °C and 120 °C.

3. CONCLUSION Today we can say

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT

61

Fig. 6: Heat recovery system for preheater waste gas

– waste heat can be effectively recovered from middle and low temperature heat sources as cement kiln preheater gases and grate cooler exhaust gases. – the waste heat recovery systems are operating reliable with steam boilers and a turbine for power generation. – the heat recovery is high. In large cement plants 30 kWh or 35 kWh per ton of clinker can be achieved. This enables the cement – plant to reduce by 20–30 % the unit power cost in cement production. – the feasibility of the heat recovery system will be given today only for large production units above 3000 t/d clinker. – the feasibility has to be calculated carefully for every single case. – further raise in heat recovery efficiency could be achieved by introducing the ORC-process. The full advantage of the waste heat recovery power generation can only be realized, if the kiln operation is stable and if there is a possibility to part time feed back a surplus of electric power into the public power distributing system. KHD Humboldt Wedag has worked out intensively the feasibility of many projects with different waste heat recovery systems, and we are in the position together with accepted boiler manufacturers to meet the necessities of the cement producers.

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 7: Heat recovery system for 2 cement kiln preheaters and 2 grate coolers

62

REFERENCES (1) (2) (3) (4)

Steinbiß, E.: Wege zur optimalen Nutzung der Abgaswärme im Zementofenanlagen mit Zyklonvorwärmer, ZKG 39, 1986, H.2, S. 75–79. Pat.-Anm. KHD AG et al, (Steinmüller) Europa Pat. -Anm. Nr. 84113750, 09. Feb. 1985. Mohrenstecher, H.: Nutzung des Wärmepotentials von Teilgasabzügen an Zementdrehrohrofen, VDZ-Kongreß, Düsseldorf, Sept. 1985. Lang, Th. A. und Mosimann, P.: Energierückgewinnung in einem Zementwerk, TIZ-Fachberichte, Vol. 107, Nr. 11, 1983, S.816–821.

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT

(5)

63

Noguchi, K.: The Japanese Cement Industry Today—New Ideas and Developments, ICS Procedings, USA, 1982. (6) Chevalley, B.: Possibilities of Waste Heat Utilisation, Fourth Techn. Meeting Arab Union, Tripoli, Libya , Oct. 1984. (7) Bornschein, G.: Wechselbeziehungen zwischen der Entwicklung der Zementproduktionstechnik und der Nutzung von Sekundärenergie, Silikattechnik 35 (1984) H.12, S.355–357. (8) Gardeik, O. und Schwertmann, T.: Rückgewinnung der Abgasenergie beim Prozezß zum Brennen von Zementklinker, Forschungsinsitut der Zementindustrie, Düsseldorf, 1982. (9) Kai, K.: Waste Heat Power Generation at Cement Plant. AFCM 8th Techn. Sympos., Manila, 1987. (10) Akita, S.: Cost reduction in Onoda Cement for the past six years (1979–1985). AFCM 8th Techn. Sympos., Manila, 1987. (11) Gustafson, T.-H.: Ritakallio, P. and Heikkilä, J.: Cleaning and heat recovery of cement kiln bypass gas with Fluxflow technology. VVT Sympos., Espoo (Finnland), Juni 1988.

DISTRICT HEATING BASED ON WASTE HEAT FROM CLINKER COOLER Ahlkvist Bo Works Director Cementa AB S-620 30 SLITE

From its Slite works, Cementa AB has been supplying a district heating scheme for a neighbouring village since 1984, generating annual heat sales of some 15 GWh from the waste heat of its No 8 kiln, a 1.4 mta capacity line, utilising waste heat from the grate cooler. Total investment costs to develop this system are put at US$ 2.0 million and by 1990 the net profit of the project are Forecast at about US$ 0.5 million per annum. History The use of waste heat for the district heating of Slite started in 1984. Slite is a small village with about 2.000 inhabitants and there would have been no district heating if it wasn’t for the waste heat possibilities. The cement plant is situated in the village. Production has been going on since 1919. Together with the big quarries the factory actually divides Slite into two parts. There are 3 preheater kilns with a total capacity of 2.0 mta. In this project we concentrated on the biggest unit (Kiln No 8) with an output of 1.4 mta. The heat distribution system Slite comprises about 700 households, half of which are in the centre of the village, and their joint demand of heat makes district heating an economic alternative. The distribution system consists of standard preinsulated heat pipes and there is a heat exchanger in each building connected to the district heating system.

DISTRICT HEATING BASED ON WASTE HEAT

65

All costs were covered by the project, so the customers did not have to pay anything to convert their systems into district heating. The total length of the distribution system is 4 km and the number of customers 20. The customers are of four categories, each taking about 1/4 of the produced energy. 1 The cement and electricity plants 2 Households 3 Other industries, municipal services, stores etc 4 Greenhouse cultivation of cucumbers Heat exchange system Kiln No. 8 in Slite has a capacity of 4700 tonnes/day and is equipped with a 5-stage preheater and a grate clinker cooler. Hot kiln gases are used to simultaneously dry the raw materials in a vertical roller mill with a capacity of 400 tonnes/hour. The clinker cooler has three grates and is equipped with a hammer crusher between the 2nd and 3rd grate. Hot air is taken out just at the beginning of the 2nd grate and is used to dry coal in a roller mill with a capacity of 30 tonnes/hour. At the end of the 2nd and 3rd grate exhaust gases are taken out and cleaned in a gravel bed filter. Exhaust gas from the clinker cooler turned out to be the best energy producer from the pollution and temperature point of view. By using these fairly clean, dry and hot gases, we were able to build a simple heat exchanger with standard components. The gases, with an average temperature of 230°C, are taken out after the gravel bed filter into a by-pass loop. By controlling the speed of the fans the water temperature is held at a desired level. The system includes two heat exchangers which are automatically cleaned by special noise nozzles. Every second month we have to clean them more thoroughly with compressed air, which requires a couple of hours for two men. Flow-sheet for the heat production is shown in Fig. No.1. Economics The total investment for the project was US$ 2.0 million with US$ 1.5 million spent on the district heating system and US$ 0.5 million spent on the heat production plant. Fig. No. 2. The interest rate in Sweden is put at 12 per cent and at the end of 1988 half the investment had been payed off. After 1990 the net profit of the project will be about US$ 0.5 million annually. The annual heat sales are approximately 20 GWh. 15 GWh are produced by waste heat from the grate cooler and the rest by oil. Further development The capacity of the waste heat production is now 6 MW but there are plans to expand it. The heat balance of the kiln shows that up to 30% of the input energy is losses in the exhaust gases from preheater. Fig. No. 3.

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 1.

Fig. 2.

The annual need of waste heat for district heating is related to the climate. Thus the need is higher during the winter period. Fig. No. 4. A problem is that the cement demand normally falls in the same period, so we stop the kilns for maintenance. Therefor it would be better to combine district heating with the generation of electrical power using process heat. As only a minor part of the high temperature waste energy is required for district heating, there is an investigation going on aiming to use waste heat for electricity production in an “Organic Rankine Cycle” process. This process uses organic fluid instead of steam.

DISTRICT HEATING BASED ON WASTE HEAT

67

Fig. 3.

Fig. 4.

This would cost us another US 2.0 million and produce about 7 GWh of electricity annually. So far the economy in such a project is somewhat uncertain with today’s prices on electrical energy. However, an electrical power producer will find the investment costs competitive to other a1ternatives. The value of the produced electricity is about US$ 0,25 million per annum. Principle for electric energy and heat production is shown in Fig. No. 5. In this case the project is a joint cooperation between the cement company, Cementa AB, and the local electricity and heat distribution company, Gotlands Energiverk AB. The villagers in Slite now have dreams of more green-houses, an indoor sea-water swimming pool and an eternal green football ground.

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 5.

HEAT RECOVERY ON THE SMOKE OF THE CEMENT KILN AND UTILIZATION OF THE RECOVERED ENERGY Jean-François BOUQUELLE Département Projets Ciments d’Obourg B—7048 OBOURG (BELGIUM)

Summary, Latent heat recovery on the smoke of wet process cement kilns is attained by means of a direct contact heat exchanger called AMAZONE. In this exchanger, water is running down in liquid sheaths around textile cables. This water gets heated up and washes the dust away. The temperature limit of the heated up water is the wet bulb temperature of the smoke. For all cold water temperatures above 40 deg.C, the hot water temperature remains fairly stable at about 72 deg.C. Weth a smoke temperature between 120 and 150 deg.C and a water content of about 0.3 kg water vapour per kg dry gas, such an exchanger one cubic meter in size, is able to warm up 40 m3/h of water from 40 deg.C to 72 deg.C. This type of heat recovery is best applicable to the heating of buldings or workshop. As long as proper care is taken to neutralize the acidity of the circulating water, the operation of the heat recovery is troublefree. At CIMENTS D’OBOURG we are running two 3 000 tons per day wet process cement kilns. After the electrostatic precipitator, smoke temperature is between 120 and 150 deg.C. Its moisture content is about 0. 3 kg water per kg dry gas. Smoke enthalpy is thus about 1000 kJ per kg dry gas. Latent heat (about 850 kJ per kg dry gas) is six times higher than sensible heat. To recover this heat we need an exchanger which will condense the water vapour without getting clogged by hydrated kiln dust. Such an exchanger exists. It was invented around 1965 by Professor LEFEBVRE of the Faculté Polytechnique in Mons. He called it the “ AMAZONE” heat exchanger. This AMAZONE exchanger consists of a bundle of synthetic textile cables, 1,5 mm in diameter, vertically tightened between two horizontal grates. Sprinklers placed above the top grate are spraying water

70

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

on it so that this water flows down in liquid sheaths around the small cables. Dust from the smoke doesn’t come into contact with the cables but is trapped in the water and washed down. The external diameter of the water cylinders is about 2 mm. The distance between cable centers being 8 mm, we can tighten 16 km of cable in a volume of 1 cu. meter. The specific contact area is higher than 100 sq. meter per cu. meter of exchanger volume. In the AMAZONE exchanger voids amount to 95 per cent of the total volume. This allows for a high gas through-flow with a low pressure drop. This heat recovery exchanger is thus very performing and perfectly suited to the recovery of heat from the smoke of wet or semi-dry process cement kilns. Primary circuit See the attached drawing for the flow-sheet of our circuit. A centrifugal fan diverts about 3.5 per cent of the total smoke flow through the Amazone heat exchanger. Pressure drop across the exchanger is between 5 and 10 mm water gauge. The hot water is pumped from the collection tank at the bottom of the Amazone exchanger to a plate exchanger where its heat is transferred to the secondary circuit water. Cooled primary circuit water is then sprayed on the top grate of the Amazone exchanger. To maximalise the heat recovery we fixed in our case the water flow at 40 cu. meter an hour. As the cold water temperature fluctuates between 40 and 60 deg.C, the hot water temperature varies only between 71 and 74 deg.C. This is because we are condensing more or less of the water vapour from the smoke and recovering mainly latent heat. Recovered heat fluctuates accordingly between 0.6 and 1.2 Gcal an hour. Our primary circuit is operating automatically, starting up when the kiln smoke temperature is above 120 deg.C and shutting down below this temperature. Special care had to be taken with regard to dust and pH of the primary circuit water. Let me speak first of the dust. The first precaution was to stop the fan and close the valve placed before it when, accidentally, the opacity measuring device shows abnormally high values for the dust content after the electrostatic precipitator. The second precaution was to stop also when the return temperature of the secondary circuit gets above 60 deg.C. Normally, the exchanger is condensing the water vapour. 1.200 litres an hour is an average figure for the condensed water. This condensed water escapes the primary circuit by the overflow-pipe of the collection tank. Doing so it is removing enough dust to keep the solids concentration in the primary circuit below 0.2 g per litre. It may happen that if the primary circuit water is not cooled enough—for instance in summer when the buildings do not require heating—the exchanger is not condensing any more but instead evaporating. If this is the case, it will rapidly get clogged by the dust. Now a few words about pH. CO2 from the kiln smoke dissolves in the primary circuit water and can bring its pH down to 3.5. Usual stainless steel cannot stand such a low pH; we have to neutralise the circulating water. We installed therefore a caustic soda dosing pump with a regulation loop. After a few accidents we had to an place electrical relay shutting down the installation for a pH below 5. Average NaOH usage is 80 mg pure NaOH per standard cubic meter of smoke.

HEAT RECOVERY ON THE SMOKE OF THE CEMENT

71

Secondary circuit But for the strict limitation of the hot water temperature to 69 à 72 deg.C, the secondary network is similar to a normal heating network. This temperature is the temperature of the primary circuit minus the 2 deg.C temperature differential across the uncoupling plate heat exchanger. Taking this restraint into account, we decided for a parallel-series network. The existing warm water central heating systems of the workshop cloakroom and offices and of the administrative buildings are fed in parallel by the network warm branch. The other buildings, stores and workshop hall had gasoil fired warm air generators. So they couldn’t be converted, we had to install completely new water to air heat exchangers. We dimensionned them specially to be able to feed them from the colder return branch. In this way, the water we send back to the Amazone exchanger is colder than it could be coming out directly from the existing radiators; we make the best possible use of the heat potential of the recovery exchanger. Our system is working completely automatically. As soon as the primary circuit starts, the pump P1 of the main secondary circuit starts also. When the primary circuit stops, this pump will keep running until the temperature at the outlet of the uncoupling plate heat exchanger drops below 50 deg.C. A flow meter controls the correct flow and provides for the recovered heat quantity calculations. Since a kiln shutdown can happen anytime, each of the users still keeps its original gasoil fired heat generator. Each user is checking the temperature of the network at the point where it is tapped off. Above a set temperature, it connects with the recovery system and switches off its generator. With dropping network temperature or flow it disconnects itself and starts again its gasoil fired heat generator. Pump P2 of the auxiliary secondary circuit will start automatically when the correct temperature is reached in the main secondary circuit. The administrative buldings will connect themselves to the recovery system when flow and temperature of the auxiliary circuit are correct. Performances Our installation is operating since the end of August 1987. The last two winters weren’t very cold so that, but for the kiln shut down periods, the heat recovery was always able to cover the needs of all the users. We know that the design temperature of the existing radiators in the workshop cloakroom and offices and in the adninistrative buildings was 90 deg.C. We calculated that, because of the 70 deg.C. temperature limit of the recovery system, these users must go over to boiler heating for an outside temperature below minimum 7 deg.C; only the users placed on the return branch can still be fed. It is a bit of pity that we had no occasion to check if this calculated figure is real. Nevertheless, from what we have been able to observe we think that the foreseen yearly saving of 300 TEP or 3.000 Gcal will be attained on average. Economics I will now go into the economics of the investment. Hourly operating cost amounts to 80 BEF an hour; this is about 4 DEM or 2 US $. The breakdown of this hourly cost is roughly as follows: electric power and supervision 25 % each, maintenance 30 % and reactives 20 %. As the installation is running about 6.500 h per year, average cost of one Gcal is 170 BEF or 8.5 DEM. Last year the cost of 1 Gcal from gasoil was as low as 660 BEF this is 33 DEM, so that the yearly saving amounted only to 1.460.000 BEF or 73.000 DEM. With the higher price of gasoil that we knew a few years before, this saving would have been three times as high.

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Making allowance for a shorter network, each branch of ours is nearly 1 km long, and for some experimentation on the system by the assistants of Professor LEFEBVRE the cost of a new investment should be somewhat lower than ours. It wouldn’t exceed 15 millions BEF or 750.000 DEM. The pay-back period is thus somewhere between 3.5 and 10 years depending on the price of gasoil.

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General diagram of the network of the recovered heat by ‘Amazone’ exchanger on the smokes of kiln No.10 of the Ciments d’Obourg

‘Amazone’ module

I am now at the end of my presentation and I wish to thank the Commission of the European Economic Community who supported this project. Its help made possible this interesting realisation of which the Faculté Polytechnique in Mons and Ciments d’Obourg are specially proud.

UTILIZATION OF WASTE HEAT FROM THE CEMENT ROTARY KILN K.-H.WEINERT Interatom GmbH Friedrich-Ebert-Straße 5060 Bergisch Gladbach 1 Federal Republic of Germany

A concept realized at the Bonner Zementwerk AG utilizes part of the shell waste heat via a hinged radiation absorber (Fig. 1) and supplying it to the building heating system and the industrial water heating system. 1. INTRODUCTION Long-term increases in the cost of energy require the application of new technologies for more rational utilization of the energy applied, in particular in the case of manufacturing processes requiring a lot of energy are released unused to the environment, whereby losses of approximately 10 %, related to the applied energy, are radiation losses from the shell of the cement rotary kiln alone. 2. SIZE OF A RADIATION ABSORBER: COMPROMISE BETWEEN CONSTRUCTION SIZE AND POWER The size of the surface of the kiln shell is subject to relatively large local temperature fluctuations, a fact which complicates the design of an absorber for the waste heat of the shell. On the one hand the average guaranteed power must be attained, on the other hand, however, the size of the absorber is not to be increased unnecessarily. The increase of the shell temperature which is caused by the erection of the absorber is not influenced by the size of the absorber. The absorber in our case was designed for the following data: –

Heat transfer surface

103 m2

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Fig. 1 Waste Heat Absorber of the Rotary Kiln of the Bonner Zementwerke AG

– – – – –

lenght Kiln shell temperature (without absorber) power max power guarantee absorber temp.

6m 290 °C 650 kW 400 kW 100 °C

The principal arrangement of the waste heat absorber plant is shown in Fig. 2 3. HEAT EXCHANGING PLATES SURROUND THE KILN (ABSORBER) The absorber consists of 12 individual level heat exchanging plates. These are so-called thermo-plates; plates which are joined together and subsequently expanded hydraulically. On the side facing the kiln they are painted with black absorber varnish and are equipped with weatherproof thermal insulation on the rear side. The absorber plates are mounted on two hinged steel constructions in such a way that they form two heptagonal half-sehlls (Fig. 2). During normal operation these completely enclose the kiln over a length of 6 m with a wall distance of approx. 0.5 m. 4. Operating systems The complete facility consists of 3 closed circuits or loops

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Fig. 2 Principal Arrangement of the Waste Heat Absorber Plant

– Absorber loop – Heating loop – Cooling loop The loops are shown in Fig. 3 Absorber loop The absorber loop absorbs the heat from the radiation absorber and transfers it via an intermediate heat exchanger to the hydraulically decoupled heating circuit. A glycol-water mixture with a freezing point of −23 °C is used as heat transfer medium in the absorber circuit. Consequently the system need not be drained during winter shutdown of the kiln. The supply temperature is 80 °C, the discharge temperature 100 °C. If less heat is consumed by the consumer, the increasing supply temperature is limited by a three-way valve, whereby that quantity of heat which is not required is discharged to the cooling circuit. Temperature monitoring is provided for the absorber surface and the kiln wall by thermocomples placed approx 20 cm from the surface of the kiln. The temperature display with limit value indication can be checked by the operating staff of the cement works in the control room. If there is an inadmissible rise in temperature, the absorber is automatically moved-by to the safety position. This process can also be initiated by the control room staff by means of a manual intervention, whereby it is possible to adapt the move back to the respective situation before the limit temperatures have been reached.

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Heating loop The heating loop is directly connected via intermediate heat exchangers to three different heating boilers. The supply temperature amounts to 90 °C and the discharge temperature to 70 °C. Integration into the connected 3 heating circuits of the operating building is effected via three-way reversing valves in the respective return lines of the heating boilers (Fig. 3). In the case of feed temperatures of more than 60 °C in the supply lines to the buildings, the intermediate heat exchanger is connected in series with the heating boilers and the supply of heat is normally provided 100 % by the absorber. The heating boilers are only switched on if the absorber power is no longer adequate. The intermediate heat exchanger is bypassed at temperatures of less than 60 °C. Cooling circuit The cooling circuit is used for adaptation to the heat requirement of the consumers. The absorber power exceeding the requirement ist discharged via a cooler cooled with well water. In addition, the cooling circuit acts as emergency cooling in the event of failure of the heating circuit and is therefore designed for removeal of the total absorber power. 5. DATA ACQUISITION SYSTEM Adequate measuring instruments and a data acquisition system were installed to determine all relevant temperatures and flows and to compute – the absorbed energy – the energy transferred to the heating loops and – the energy transferred to the coolingloop. These data were accumulated and the computed mean values were printed hourly. 6. RESULTS OF OPERATION The acceptance measurements were part of the measuring phase. The results are shown in our next Fig. This Fig. 4 shows the absorbed power as a function of absorber inlet temperature and kiln shell temperature. For a kiln shell temperature of 340 °C (which corresponds to theoretical layout temperature of 290 °C without absorber) a power of approximately 600 kW was expected, but a power of only 480 kW was achieved. The difference can be explained by the convection losses caused by a large natural convection flow through the lower and upper gap of the absorber. These convection losses were estimated at approx. 220 kW, the half of which could certainly be used by the installation of the top and bottom cover sheets as it was planned in a second part of the measuring phase. Therefore it can be stated that the expected power of approx. 600 kW could be achieved with a well functioning bottom and top cover sheet.

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Fig. 3 Operating systems

78

7. PROJECT REALIZATION In the first six month of 1984 the basic engineering work was performed and first orders for the components

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Fig. 4 Power of Absorber in closed Position versus Temperature of the Kiln Jacket

to the Subcontractors were placed in autumn 1984. Because of extensive costs of the absorber steel structure this had to be redesigned: The design was changed from a carriage design to a swivelling one. Assembly was finished on schedule in April 1985 and the plant was commissioned successfully. No principial difficulties occurred. Only minor corrections have to be carried out during the commissioning phase to adjust the components to the specified requirements. For examination of the influence of various constructive elements on the convective losses only the cover sheets at the sides of the absorber were mounted. The bottom and top cover sheets were to be mounted later. 8. COSTS The following table shows the real costs in comparison with the forecast ones: Phase I

Content Planing – Optimization

Forecast Costs in DM 62,324,−

Real Costs in DM

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Phase

II

III

Content – Detailed design – Specification Carrying out – Award – Supervision of construction – Commissioning Measuring Program – Data acquisition – Technical-Economical Evaluation – Documentation Total

Forecast Costs in DM

Real Costs in DM

591,176,–

906,256,–

100,000,–

74,205,–

753,500,–

980,461,–

The forecaste costs have been exceeded by than 20 %, especially caused by the steel structure, a redundant power supply and more extensive engineering work. Taking the real costs fo the project and the infrastructure of the Bonner Zementwerke as a basis it can be stated that the costs for future plants will not drop below approx. 600,000,– DM. The technique of steel structure, absorber plates and heat transfer loops is conventional and cannot be reduced for future plants. Rotary kiln waste heat absorber plants with its high investment costs are only able to compete with conventional industrial systems if the degree of exploitation could be increased from the actual value of approx. 25 % of this project. 9. DEGREE OF SUCCESS AND OUTLOOK The absorber plant worked very well up to the moment the whole cement production plant was shut down. The predicted energy saving of 76.5 TOE could not be proofed because of the short operating period. But there is no doubt that the absorber plant would have fulfilled this requirement, because the installed power of approx. 600 kW (with top and bottom cover sheets installed) exceeds the installed power of 540 kW of the conventional heating system of the Bonner Zementwerke AG. For bigger follow-up plants investment costs for the complete system of approx. 900,– DM per kW effective power are estimated. Thus, at a high annual rate of utilization, the system definitely achieves the amortization period required today for energy-saving investments. The utilization of radiation waste heat for the internal generation of electrical power is conceivable for big plants. REFERENCES (1)

Weitzenkamp, H. Interatom-Report, Id.-No. 39.05625.6.A Utilization of Waste Heat from a Cement Production Rotary Kiln for Heating and Domestic Water Supply of Buildings

ENERGY SAVING BY UTILISATION OF HIGH EFFICIENCY CLASSIFIER FOR GRINDING AND COOLING OF CEMENT ON TWO MILLS AT CASTLE CEMENT (RIBBLESDALE) LIMITED, CLITHEROE, LANCASHIRE, UK PETER FREDERICK PARKES Milling Department Manager Castle Cement (Ribblesdale) Ltd, Clitheroe, Lancashire, UK

CASTLE CEMENT (RIBBLESDALE) LIMITED Castle Cement is jointly owned by two Scandinavian companies, Aker of Norway and Euroc of Sweden. The cement works at Clitheroe was established in 1936 and now consists of: 2 wet process kilns 1 000 tpd. 1 dry process kiln 2 300 tpd. 10 cement mills6 at 600 kW 2 at 2 000 kW 2 at 1 000 kW with an annual production of over 1M tonnes. REASONS FOR INSTALLING A SEPARATOR With the upturn in the UK market we were short of milling capacity. Various options were considered, namely: a) a new cement mill; b) high pressure clinker grinding roll set; c) a high efficiency separator.

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Fig. 1. 9 and 10 cement mill open circuit system

We decided to install a high efficiency separator. The principal reason for selecting this option was that it gave us the required extra quantity of cement with the lowest capital investment. The lower finished cement temperature with this option was an additional advantage. Sturtevant carried out the process design and guaranteed a 25% increase in throughput. ORIGINAL LAYOUT OF 9 AND 10 MILLS The mills are F L Smidth Unidan mills ø 2.9m×12 m, 1500 Hp (1070 kw). They were originally installed in 1961 as slurry mills. No. 9 was converted to a cement mill in 1984 and No. 10 in 1987, both as open circuit mills (see Figure 1). Before conversion to closed circuit Mill 9 had a 1st Chamber length of 3.7 m, with 27 tonne of grinding media ø 60 to ø 90. Chamber II was 7.6 m long with 57 tonne of media ø 15 to ø 20. Mill 10 1st Chamber length was 3 m with 20T of ø 60 to ø 90. Chamber II was 8.45 m long with 70 tonne of grinding media ø 15 to ø 20. NEW LAYOUT OF CLOSED CIRCUIT OPERATION The cement from the mills is conveyed to the new Sturtevant SD120 separator, the finished product cement from the separator is collected in a Redecam dust collector rated at 110000 m3/hour. The cement from the Redecam bag filter is then transported to the silos using the existing belt and elevator transport system (see Figure 2). The coarse tailings from the separator are returned to the mills via air slides. The second of these air slides is equipped with a proportioning valve, that splits the tailings equally between two weigh belts. The weight signals from these belts are used to determine the position of the proportioning valve, so as to deliver equal amounts of tailings to each mill. This signal is also used in a loop controller with the clinker and gypsum feeders, to maintain a constant feed to the mills, i.e. new feed plus tailings equals a constant. The mill internals were altered on Mill 10 to give a longer 1st Chamber of 4.1 m. The media levels were also increased. Mill 9 Chamber I effective length 3.7 m with 29 tonne of grinding media ø 60 to ø 90. Chamber

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Fig. 2. 9 and 10 cement mill closed circuit system

II effective length 7.6 m with 69 tonne of grinding media ø 15 to ø 20. Mill 10 Chamber I effective length 4. 1 m with 30.5 tonne of grinding media ø 60 to ø 90. Chamber II effective length 7.2 m with 72 tonne of grinding media ø 15 to ø 20. In order to improve the air flow through the mills Bazzi inlets replaced the original F L Smidth scooping devices. Bazzi outlet grates were also employed, but the original F L Smidth combidan diaphragms were retained. INSTALLATION—INTERFERENCE WITH PRODUCTION The conversion was carried out from the end of December 1988 into January 1989, as there is always a drop in cement demand at that time of year. The mills were shut down on 22nd December and re-commissioned on open circuit at the beginning of February. The total down time was 40 days, during which time the following work was carried out: 1. 2. 3. 4.

Installation of new mill inlet chutes. Re-positioning of the diaphragm in Mill 10. Installation of new outlet screws and air slides. Installation of a new bucket elevator.

Trials on closed circuit grinding commenced on 8th February. The system was fully commissioned and running continually on closed circuit by 10th March. This included changeover to a new control desk and microprocessor control system, which had to be fully checked out and proven, before we could allow night time and weekend running on closed circuit. PERFORMANCE AND OPERATION The average combined production for the two mills on open circuit in November and December was 42 tph. During initial commissioning trials on closed circuit, production varied between 50 and 58 tph.

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Fig. 3. Castle Cement (Ribblesdale) Cement Mills 9 and 10, SD 120 classifier Tromp Curves for O.P.C. (3600 Blaine)

At the final performance trials a maximum of 66 tph was attained, but this eventually settled down to 60 tph on a Blaine of 3600, an increase of 43%. There are a number of factors influencing this increase in production. The charge levels on 9 and 10 Mills were also increased during the installation of the classifier in accordance with Sturtevant’s recommendations, as part of the conversion to closed circuit. The variation in clinker grindability is also a significant factor, as other mill throughputs were low in November and December, and improved again at the beginning of the year. Another factor is that the mills had been achieving very high run factors for the three months preceding the shut down, so consequently performed better on re-starting following repairs during re-commissioning on closed circuit. Though it is extremely difficult to quantify the improvement directly attributable to the installation of the classifier itself, in view of the other influencing factors mentioned above, we are certain that at least 25% of the increase is due to the classifier and the guarantee has been satisfactorily met. The separator operation is very consistent, it produces a very stable cement in terms of Blaine and particle size distribution. The system also operates very reliably and run factors of 90% have been achieved. Typical tromp curves as achieved by the separator are given in Figure 3. Maximum production was attained with maximum air flow through the separator. The new system is still susceptible to changes in clinker grindability, but not as markedly as it was on open circuit. ENERGY CONSUMPTION During 1988 whilst the mills were running on open circuit, the average departmental power consumption was 45.29 kWh per tonne. At an average of 60 tph the power consumption was found to be 39.25 kWh/t, an improvement of 13%. On one test over a period of five hours, 66 tph at 37 kWh/tonne was achieved.

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BENEFITS (See Table 1) 1. Increased Production As stated previously, this was the main reason for installing the high efficiency separator, and with an increase of around 40%, of which at least 25% is directly attributable to the classifier, this has been the greatest benefit. 2. Improved Strengths The 28 day strength of the cement produced on the high efficiency separator has shown an improvement of over 6% against open circuit produced cement, i.e. an average of a series of tests showed strengths of 48.3 N/mm2 against 45.3 on open circuit produced cement. 3. Cooler Cement Previously the cement was delivered to the silos at 120°C. On closed circuit this temperature has fallen to about 75/80 °C. This is due to the cooling effect of the separator, with ambient air as well as air from the mill ventilation. 4. Improved Energy Consumption An average improvement of up to 6 kWh/tonne has been found on the closed circuit system; an improvement of 13%. This saving in power consumption has been achieved at the same time as increasing production, improving cement strengths and reducing cement temperatures, as stated above. TABLE 1. Comparison open to closed circuit

Tonnes per hour @ 3600 Blaine Energy consumption 28 day strengths (100 mm concrete cubes to BS 4550) Cement temperature

Open

Closed

Change

42 tph 45.29 kWh/t 45.3 N/mm2 120°C

60 tph 39.25 kWh/t (at 60 tph) 48.3 N/mm2 80 °C

+ 43% −13% +6% −40 °C

DISCUSSION

TO: MR STEINBISS DR TOM LOWES, Blue Circle Cement QUESTION Does the 3000 tonne/day you mentioned as a minimum size capacity plant for the installation of waste recovery for electricity generation, include waste heat recovery from both the cooler and the pre-heater exchanger? If it did, what price/kWh would you expect for break-even investment? ANSWER Yes, it included the waste heat from both the preheater and the cooler. The break-even price cannot be given. You cannot give a general figure because of the assumptions which would have to be made. CANCELA DE ABREU, Secretary of State for Energy, Portugal QUESTION What type of fluid would you propose using in the ORC System—DR114 or a different one? ANSWER Different fluids are suitable for different applications. An American company uses hydrocarbons as a fluid, for example methane, used as a fluid. R K GUPTA, J K Cement Works, India QUESTION In your case study you mention a 1000 tonne/day plant, but in your conclusion you state that the system is only suited to plants with 3000 tonne/day capacity. Could you clarify whether this is from the technological point of view or investment criteria?

DISCUSSION

87

ANSWER The figures have been standardised at 1000 tonne/day to allow for ease of multiplication. It is not intended to give the impression that ‘it is feasible to equip a 1000 tonne/day kiln’. MR F AELLEN, Holderbank, Switzerland QUESTION Why is there no breakthrough in the use of the Organic Rankin Cycle? ANSWER This has been considered for many plants but there are no satisfactory reference plants in the cement industry. The ORC is operated satisfactorily in other industries and will eventually be applied in the cement industry. MR SIRCHIS, Commission of European Communities STATEMENT

Regarding the Organic Rankin Cycle—this system is going to be installed to recover heat from a reforming plant in the Portuguese chemical industry. MR H TAKAKUSAKI, NCC, Japan QUESTION What are the advantages of organic fluids over water? One disadvantage is if the fluid leaks into the furnace gases, which could be dangerous. ANSWER The fluid is not actually dangerous. You need another fluid to go on the ORC which will operate at lower temperatures than water will. If you use an organic fluid you can still be efficient even at lower temperatures. TO: MR AHLKVIST—No questions. TO: MR BOUQUELLE MR SIRCHIS, regarding payback being dependent on fuel oil costs. QUESTION What is the cost of the fuel given by the two units in the payback period? ANSWER The low cost 650 GCal/Belgian Franc=6 BEF/litre gas oil, the high cost 17 BEF/litre gas oil. The present price in Belgium of 8 BEF/litre (0.2 ECU/litre) gives a payback of between eight and nine years. MR NOHLMANS, Novem, Netherlands, Agency for Energy QUESTION Have you done any pollution measurements on this type of equipment? ANSWER The smoke from the kiln is 60% cleaner than otherwise. The water is polluted which requires additional treatment. The heat exchanger is used elsewhere as a reactor for retaining sulphur from fumes in a plant making coke from coal. MR AELLEN, Holderbank

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QUESTION Regarding the layout of the heat exchanger, the two fluids are in direct contact. If you had a bigger system, how would you lay out your heat exchanger? Would you just extrapolate or would you calculate? ANSWER This is a question for the designers of the heat exchanger. For bigger machines you can alter the configuration in many ways. MR PER KNUDSEN, Gotlands Energiverk AB, Sweden QUESTION How far away is the town of Mons from the cement plant? ANSWER About 4 km. MR PECH, Vicat Tour Can, France QUESTION Do you know if you can use it as a de-sulphurising unit? ANSWER Technically it is possible, but whether it is economic is unknown. PROFESSOR MARIO NINA, University of Lisbon, Portugal QUESTION Did you have any fouling problems with your plate heat exchanger? ANSWER The dust content is around 0.2 g/litre of water. The heat exchanger is of 4 pass configuration designed with removable bottom plates to enable it to be cleaned. TO: MR WEINERT DR TOM LOWES, Blue Circle Cement QUESTION Was there any detriment to the refractory or shell life? ANSWER The shell temperature has increased by between 30 and 50°C. Unfortunately the plant closed after six months for economic reasons. The plant was dismantled and taken to Turkey and there was no apparant damage to either the shell or the refractory. TO: MR P F PARKES DAVID HARGREAVES, Editor, International Cement Review QUESTIONS How much did it cost? What was the payback period? What are the disadvantages? If you did it again, would you do it differently? ANSWERS

DISCUSSION

The project cost was £1000000. The payback period is difficult to estimate and a figure cannot be given just now. There are no disadvantages—there are only advantages. We would modify some of the ancillary plant if we did it again, but the separator itself has not caused any problems.

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“HOLDERBANK’S” ENERGY MANAGEMENT IN THE 1990S M.BLANCK “Holderbank” Management & Consulting Ltd, CH-5113 Holderbank/Switzerland

SUMMARY Electrical energy costs play a major role within the production cost structure of cement and mineral processing plants. Today reducing specific electric energy consumption most often means engineering solutions for improving equipment or introducing new technologies. Reducing consumption through better management of electricity use in day-to-day operations, however, is seldom found. The reason why is obvious. There is simply not enough useful information, readily available to enable people to monitor and control the use of electrical energy. To meet this industry-wide need “Holderbank” Management & Consulting Ltd. has developed a number of tools and organizational procedures to upgrade the quality of energy management. 1. INTRODUCTION Increasing electricity rates in many countries and very complicated tariff structures make further energy cost reduction difficult. However modern information technology offers new opportunities to improve the quality of energy management. In the foreword of the recently issued OECD *) and IEA **) publication “Electricity End-Use Efficiency (1)” we can read: “Electricity demand has been the fastest growing form of final energy among IEA countries over at least the last thirty years of energy development. While the electrification of OECD economies has led to better

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quality of life and increased economic efficiency, there remain opportunities for improved efficiency in the use of electricity itself.” We are convinced that this statement: “…there remain opportunities for improved efficiency in the use of electricity itself” is also very true for the cement industry. For us, using these opportunities means developing rational electricity use by the systematical application of modern information technology. This is “Holderbank’s” objective in the electrical energy management field for the 1990s. Projects and activities aiming at this objective will be presented in this paper. 2. ENERGY MANAGEMENT FOR RATIONAL ELECTRICITY USE Energy management can be structured into two areas (see figure 1): – Energy logistics, and – Energy utilization. Energy Logistics The purpose of energy logistics is to make power available at optimal cost while using the power contract the most efficient way. Energy logistics considers both power supply from the utility as well as selfgenerated power. As a management task, this can be realized in two ways: – Active power contracting, and – Dynamic contract use optimization. Power Contract The power contract provides the framework for considering utility power supply and for self power generation. It specifies the best available conditions for the particular plant’s requirements. For example, contracts can stipulate different types of time-of-use pricing and load management controlled by the utility or by the consumer. Yearly review of the contract regarding cement market demand and plant conditions also offers interesting options for contract adaptation. Contract Use Optimization The power contract only provides maximum benefit when it is used in the most efficient way. Therefore, contract use optimization is an objective which continuously has to be supervised and if necessary adjusted. For example, time-of-use tariffs very often specify up to four different rate-periods during the day. Utilization of such complex rate structures requires dynamic energy or production planning and consumption monitoring, as well as peak load levelling by the utility or by the customer himself.

*) OECD=Organization for Economic Co-operation and Development **) IEA=International Energy Agency

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Savings Potential and Results These activities lead to reduced electricity cost per consumed KWh. According to our experience, cost savings of up to 7% should be achievable in the maturity cases. Energy Utilization Energy utilization is an activity area that improves energy efficiency or, in other words, reduces specific energy consumption. It includes the introduction of new process and equipment technology, and in parallel, operation optimization. New Technology The objective of this branch is to identify plant areas for energy efficiency improvement by the introduction of more efficient equipment or new technology. Typical measures are, for example, the replacement of inefficient equipment or oversized motors and, modernization by the introduction of variable speed control for motors, high efficiency separators, roller presses etc. Operation Optimization Energy efficiency is always dependent on the operating conditions of plant equipment. The objective is to bring and keep operation on an optimal level. For this purpose, all relevant process and machine parameters have to be continuously monitored. While most of the required process parameters are available and recorded. These days there is a general lack of energy data. We find that the area of energy management is the least developed area today. Savings Potential and Results The savings potential for redesigned equipment or new technology can usually be calculated and proved in advance. On the other hand, expected savings from improved operation can normally not be assessed in advance because of lack of suitable energy data. Therefore, the achievable savings are in general unknown and can only be calculated after the improvement measures have been applied for a longer period of time. 3. TODAY’S ENERGY MANAGEMENT SITUATION Energy logistics is the most developed area of energy management. The reason for this is obvious. By the time utility pricing practices like time-of-use tariffs and demand charges came into effect, corresponding measures were consequently developed and introduced on the consumer’s side—like increasing the low tariff consumption and load shedding procedures. Although there are still interestingly achievable saving potentials (up to 7% of the total bill) in this area, we are convinced that more focus is now required in the area of energy utilization. In order to reduce specific energy consumption by

Figure 1: Structure of Energy Management

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– Improvement of operation – Replacement of outdated equipment – Installation of new technology two fundamental provisions have to be developed and implemented. These are: – The energy management information system, and – The energy management organization system. They form together with the plant itself the closed energy management cycle (see figure 2). According to the experiences from the past decades of the computer age, there is no doubt that every information system needs a suitable organizational structure to be efficient. Without adequate organization, the information system will not work sufficiently or will even die. In conclusion, to make the energy management cycle work, it needs both – Computers providing useful information, and – People who can act accordingly. In order to accomplish this energy management cycle, there are two major gaps to overcome. These gaps are: – Energy data and information preparation, and – Energy management organization. As a result of the importance of rational electricity use for increased profitability, and in view of sharper environmental regulations as well as further shortages or price rises of electricity in the forth-coming years, “Holderbank” has decided to focus its activities on closing the above mentioned two gaps. In the next section you will find our corresponding project objectives, development statuses and experiences. 4. ENERGY MANAGEMENT PROJECTS Energy Information Management The following project is a research project which is currently in preparation in Switzerland. Situation Efficiency improvement is the central subject matter of every engineer’s activity. On the other hand, the awareness of how to deal with energy, especially electricity, is not yet far enough developed in modern plant operation. Of course, there are already many information systems implemented. But energy information systems and related energy management functions within the daily operating routine hardly exist.

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Figure 2: Energy Management Cycle

“HOLDERBANK’S” ENERGY MANAGEMENT IN THE 1990S

Many plant people, especially those on lower hierarchical levels, do not feel really concerned about energy conservation. The reason why is obvious. They do not have much or even any useful energy related information for comparison in their day-to-day routine work. Even if actions for energy savings are undertaken, the energy gain cannot be proved properly because of a lack of suitable information. Because of this situation, there is generally not enough incentive or motivation on the individual hierachical plant levels for real energy conservation.

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Therefore, the companies “Holderbank”, ALUSUISSE/LONZA and the Swiss Federal Institute of Technology are now preparing a research and development project named “Energy Information Management in Industrial Plants”. Objectives The purpose of the project is to research and develop information methods and means for rational electricity use. In particular, in this project we have to answer the question: How can energy management be integrated into the management structure on both corporate and plant levels? Furthermore, within the management structures, the following question has to be clarified: What is the necessary responsibility structure and the required range of competence of plant people that can largely influence energy consumption? The new concepts and information tools which have to be developed shall lead to substantially enhanced energy management quality and to greater energy savings potential. In conclusion, this project shall provide an applicable: – Energy management information system, and – Energy management organization system which together complete the energy management cycle which has been previously mentioned. Status At this moment the project is in the financing stage. It is intended to start in early 1990. Energy Information Preparation and Energy Management Organization The following described results and experiences were achieved within the framework of different energy management system implementation projects. Besides better energy logistics, these projects have also the goal to enable the plant people on all levels to improve the plant’s energy utilization. Situation Although electronic monitoring and processing of all important operating data is now a matter of course in many cement plants, electrical energy data is still monitored “by hand” in practically all plants: normally once a month. In many cases, the energy figures obtained cannot even be clearly assigned to individual departments and groups of machinery. The reason for this is the complicated entanglement of energy inputs and energy meters which has built up over the years due to plant alterations. The interfaces for energy consumption measurements often run right through the cost centres, and the energy consumption has to be allocated by estimate. The only purpose served by such conventional power bookkeeping exercise can be an approximate allocation of the energy consumption and costs to the departments. This inaccuracy makes it impossible to identify any existing potential for energy saving. In other words, the energy consumption figures produced in this way are useless as guide figures within the plant energy management systems or as a basis for the rational use of energy.

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Objectives The objectives of “Holderbank’s” energy management implementation projects can be summarized as follows: – Recording of all energy flows without exception down to the level of important individual subprocesses, – Greater transparency as precondition for disclosing potential savings, – Involvement of energy information plant organization, and by that means, ensuring rational electricity use. Status and Results At present these energy management systems are in operation in two Portuguese cement plants. Engineering and installation is taking place in three other European plants. The complete energy data for almost one year is now available for each of the first two factories. These are the Outao Cement Plant of SECIL /Portugal and the Souselas Cement Plant of CIMPOR/Portugal. In one factory, we have investigated the data in greater detail for two months jointly with the plant management. It has shown in a first review, during a three day workshop, that there is a remarkable volume of energy consumption which can be considered as savings potential. The following examples explain the principle of the investigational approach which is in progress now at SECIL’s Outao Plant. Example: Low Efficiency Days versus High Efficiency Days The graph in figure 3 shows a raw mill (roller mill) unit with its recorded raw meal production output and the related energy consumption on a daily basis. The example shows the data for the month of April 1989. Every number in the graph indicates a single day of this month. The area is subdivided into three sections: i) The range of “normal” days (normal efficiency) ii) The range of “bad” days (low efficiency) iii) The range of “good” days (high efficiency) At first view there are three types of days which call for more attention: i) The “bad” days ii) The “good” days iii) The days with no production but still with a remarkable quantity of energy consumption. As a next step, a closer look is needed at the low and high efficiency days. For illustration the 11th of April 1989 is chosen as a so-called “bad” day and the 29th of the same month as a so-called “good” day. In figure 4 the different power demand profiles (15-minute integration values) of each of these days are shown. Almost the same quantity of raw meal was produced (namely 7’000 tons a day) during each of the two days. But, as a matter of fact, on the 11th of April the raw mill consumed US$835 more energy than on the 29th of April. (US$835 is based on an average cost of 5 cents per KWh).

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Figure 3: Low Efficiency Days versus High Efficiency Days

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Example: Wasted Energy for idling Equipment This example highlights those days with no production but a considerable quantity of energy consumption nevertheless. Figure 5 shows how much energy is consumed when production is zero. This graph shows the demand profiles of three of such “zero-production” days. For better comparison, the same power scale as in the graphs of figure 4 is chosen.

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Fiqure 4: “Bad” Day: April 11 versus “Good” Day: April 29

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In conclusion, in January 1989 there was a 25 MWh consumption for idling motors in the raw mill section alone. This energy is worth US$1’265.

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Figure 5: Wasted Energy for idling Equipment

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Follow-Up and the Establishment of an Energy Management Team These examples, showing only one production department for two months, highlight the savings opportunities possible with analysis and control. Especially if the savings are projected on the entire plant for an entire production year.

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Of course, for the time being, we can only assume that the potential savings can also be realized. Evaluating this in more detail is the very task we have for the future months. When this project was established at SECIL it was also apparent that an energy management organization would be required in order to integrate the energy data and information (which flow day-by-day) into the daily routine work. Accordingly, the second goal of the before mentioned workshop was to establish an energy management strategy and an interdisciplinary energy management team. The energy management team of SECIL now consists of: – – – –

The production manager, Two members from the production management department, Two members from the maintenance management department, One member from the management staff.

The tasks, competences and objectives of this team are defined in the related strategy. One of the first steps of the team is to put the strategy into practice by improving the energy utilization in the raw and cement mill sections as mentioned before. This evaluation project was started at the beginning of October 1989. The preparation of a comprehensive report is planned by May 1990 for the IEEE Cement Conference in Tarpon Springs, Florida, USA. By then we will have more (exact) figures, specifically for the quantity of energy saved. 5. CONCLUSION The presented projects of the first years of the 90s show the direction of “Holderbank’s” energy management development programme. In conclusion, energy data preparation and energy information management imbedded in an energy management organization form the two key systems of the energy management cycle as shown in figure 2: – The energy management information system, and – The energy management organization system. In a period in which further shortages and price rises of electricity are foreseeable in many countries, it seems to be of pressing importance to use the existing energy as efficiently, i.e. rationally, as possible. In addition to this, attempts should always be made to reduce the energy costs to a minimum, purely on the grounds of operational economy. Energy management is hence being continually improved and developed with the application of the most modern information technology. BIBLIOGRAPHY AND REFERENCES (1) (2) (3)

OECD/IEA Publication: Electricity End-Use Efficiency. OECD Publications Service Paris, 1989. Blanck, M.: Energy Data Analysis. Zement-Kalk-Gips, Bauverlag Wiesbaden (1989) No.6 pp 288–290. Spreng, D.: Energiesparpotentiale in Industriebetrieben. NFP44, SIASR, St. Gallen, 1986.

ENGINEERING AND ENERGY SAVINGS Jean DUMAS CITEC, Centre Industriel et Technique des CIMENTS FRANÇAIS Les Technodes, 78930 GUERVILLE, FRANCE

Summary The various means used to make energy gains and savings in four Ciments Français plants are described. They refer to improvement of process, reliability and simplification of equipement and use of cheaper fuel. 1. INTRODUCTION Various means may be envisaged to make energy gains and savings in a cement works: – an initial way is to improve the process in its principle, for instance, setting up of air recycling, or in its local adaptation to the material treated, for instance by preliminary drying and crushing of the raw materials, – a second way, is to improve the installation by its reliability and simplification, eliminating weak points in installation means, eliminating the cause in unstable operation which always consume energy, – lastly, the gain may be economic by converting furnace and kilns to a cheaper fuel (coal, petrol coke, waste fuels). This list is certainly not exhaustive, but it summarizes the main lines of the modifications that we have made to four of our plants in order to improve their productivity and their energy efficiency. These four plants are at BEAUCAIRE, BEFFES, BUSSAC AND COUVROT.

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2. THE CASE OF BEAUCAIRE 2.1 THE PLANT BEFORE MODIFICATION Before its modification, the BEAUCAIRE plant was schematically composed of: – – – –

storage of raw materials; these raw materials are four in number: clay, lime, bauxite and pyrite ashes, 3 dryer mills, 2 homogenization units, one serving kilns 3 and 4, the other kiln 5, 3 semi-dry process lines, each consisting of a LEPOL grate, a POLYSIUS rotary kiln and a FULLER cooler; two of them had a capacity of 650 t/d and the third had a capacity of 1 450 t/d, – clinker storage of a capacity of 20,000 tons, – a cement milling workshop having a birotator mill of 1 100 kW, and two compound mills of 1 690 kW and 2 800 kW The objectives of the investment were the following: 1 —To simplify the operating diagram of the plant by grouping together the production of the clinker into a single manufacturing line. 2 —To reduce the specific thermal consumption. 3 —To eliminate the use of fuel oil and gas for drying raw materials. 4 —To conserve production capacity 2.2 MODIFICATIONS The new burning line has been constructed on the basis of the 1 450 t/d kiln by transforming it into a dry process kiln; the increase in capacity has been obtained by setting up a pre-heating tower with precalcination RSP ONODA with separated air; the pre-heating tower comprises five stages which provide for better utilization of heat of the exhaust gases. Temperature is approximately 320°C at the output from the tower. The cooler has been replaced by a FULLER cooler of 70 m2 with 2 grates. The three raw material mills have been replaced by a PFEIFFER roller mill driven by a 2250 kW motor, its nominal capacity being 210 t/h. The total conversion of the fuel consumption to coal and petrole coke has required a supplementary FCB ball mill. These various transformations have been accompanied by modifications concerning the organization of the production flow, storage and improvement of the proportioning of the raw materials. 2.3 BALANCE SHEET Independently of the reliability of the equipment, this reliability being linked with the simplification of the production flows, the energy gains are as follows:

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Concerning heat consumption, it has fallen from 940 Kcal/kg to 825 Kcal/kg. This gain is due: – to the changeover of the semi-dry process to the dry process, – to drying of the raw material by gas coming from the preheater, – feeding of the coal mills by air from the cooler. The increase in capacity, linked among other things, with the setting up of precalcining results in the reduction in fixed losses related to one kg of clinker. On the other hand, the electrical specific consumption of the raw material milling workshop has fallen from 30 kWh/t to 20 kWh/t of raw material, and this is due to the good adaptation of the vertical mill to the BEAUCAIRE raw materials.

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BEAUCAIRE PLANT OBJECTIVES SIMPLIFICATION OF FLOWS

RESULTS 1 RAW MATERIAL MILL INSTEAD OF 3 1 KILN INSTEAD OF 3 IMPROVEMENT OF ENERGY EFFICIENCY THERMAL GAIN OF 125 KCAL/KG ELECTRICAL GAIN IN RAW MATERIAL MILLING 30 % ELIMINATION OF FUEL OIL AND GAS CAPACITY UNCHANGED CAPACITY MAINTAINED AT 2800 T/D

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3. THE CASE OF BEFFES 3.1 THE PLANT IN ITS INITIAL STATE The conversion of the wet, into semi-dry process installations, goes back some fifteen years for the BEFFES plant. The conversions that have taken place since have taken place in stages. At the beginning of the conversions that we will describe, the plant comprised two kilns, one of 1150 t/d, the other of 1350 t/d. Granulation was performed by mixing paste and raw meal. One of the kilns was equipped with a LEPOL grate and the other was a kiln with a cross shaped internal exchanger. The two coolers were FULLER coolers. The cement milling workshop comprised four mills: – – – –

an ESCHER WYSS mill of 1200 kW in closed circuit, an FCB compound mill of 1200 kW in open circuit, a POLYSIUS compound mill of 2500 kW in closed circuit, and a small POLYSIUS compound mill in open circuit.

The structure of the plant was relatively complex. 3.2 CONVERSIONS The objectives of the conversions are very similar to those of BEAUCAIRE. These conversions concern the burning workshop, the cement milling workshop and the raw material mill furnace. . Handling of raw materials Handling of raw materials has been simplified which has resulted in the elimination of the old gantry halls. . Burning workshop A single kiln has been retained. To increase its capacity and improve its thermal performance, precalcining has been installed. The burner is located at the front of the LEPOL grid, and receives 20% of the total flow of coal. In order to withstand the new thermal loads, the bricks situated in the decarbonation zone have been replaced by others, richer in alumina; the grate plates are now in 30 % chromium steel. The temperature of the grate is controlled and triggers an alarm in the case of too high a temperature. The height of the layer has risen from 18 to 24 cm and the rate of decarbonation from 24 to 47 %. Cement milling workshop

From the old cement milling workshop, only the 2500 kW mill has been retained; the ESCHER WYSS mill was old and the trunnions of the two FCB and POLYSIUS compound mills were of too small a cross section. These mills have been replaced by a compound 1700 kW POLYSIUS mill, a mill which operates in open circuit. . Raw material mill furnace In order to reduce energy costs, the raw material mill furnace has been converted to coal fuel.

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3.3 BALANCE SHEET The current performances are as follows: – thermal consumption, firstly the recycling of the air cooler represents a gain of 46 Kcal/kg, and secondly the installation of precalcining provides an increase in production from 1 370 t/d to 1 800 t/d which has permitted a reduction in the specific consumption of the kiln alone from 800 Kcal/kg to 785 Kcal/kg. The total specific consumption of the plant has fallen itself by 55 Kcal/kg. – the cement milling workshop has been greatly simplified since only two mills are used for production and energy performance has been maintained.

BEFFES PLANT OBJECTIVES SIMLIFICATION OF FLOWS

RESULTS 1 SINGLE KILN INSTEAD OF 2 2 CEMENT MILLS INSTEAD OF 4

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BEFFES PLANT OBJECTIVES RESULTS IMPROVEMENT IN ENERGY PERFORMANCE THERMAL GAIN OF 50 KCAL/KG ELIMINATION OF FUEL OIL AND GAS ADAPTATION OF CAPACITY CONVERSION OF THE RAW MATERIAL MILL FURNACE TO COAL INCREASEOF THE CAPACITY OF THE BURNING LINE BY 27 %

4. THE CASE OF BUSSAC 4.1 THE PROBLEM RAISED The objectives to the modifications to the BUSSAC plant were:

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1 —To solve the problem of the raw material preparation 2 —To increase the production capacity from 1800 t/d to 2640 t/d 3 —And to improve the thermal performance In the BUSSAC quarry, there are two raw materials: lime, or high grade, and clay material, low grade. This very damp and plastic clay material is sticky and raises great problem in handling. In addition, the low silica module requires an important addition of sand. The initial design of the plant had naturally taken account of these factors. The preparation of the raw material comprised: – – – –

2 crushing stages, 2 pre-homogenizations, one for the high grade, the other for the low grade, vibrating bottom bins for the buffer storage of sticky material, pre-drying carried out in a dryer crusher with recirculation of dry meal to produce a coating that avoided sticking to the rollers.

The raw material without sand and the sand were crushed separately in the birotator mill. The kiln was a planetary cooler kiln with a DOPOL preheating tower. Operation presented difficulties: – for the raw material, the bottom of the vibrating hoppers clogged and the control of the low grade flow was not reliable, – in the kiln and the dry crushing of the raw material, the thermal consumption was relatively high because of the temperatures required to dry the raw materials, – the planetary cooler induced process and mechanical problems (mediocre clinker cooling, fatigue in the furnace casing).

4.2 MODIFICATIONS Raw material handling and preparation: – the reclaiming of low grade by bucket wheel was replaced by a bucket scraper, – the buffer storage hoppers of the low grade have been replaced by a storage belt, – the dryer crusher by an aerofall having a diameter of 8.2 m, which dries the raw material and preliminarily crushes it. As regards the kiln: – precalcining with IHI separate air has been set up in the preheating tower, – the planetary cooler has been replaced by a CLAUDIUS PETERS grate cooler with integral recirculation. All of these conversions have been supplemented by setting up an expert system which provides for the automatic control of the kiln on the basis of rules that have been defined by the actual users and data

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(temperature, pressure) provided by sensors located in the plant. In particular, it takes into account the results of the automatic ISYS free lime analyser operating continuously. This automatic control system, by regularizing and optimizing the operation of the burning line continuously, improves both the energy performance and the quality of the clinker. 4.3 THE BALANCE SHEET As regards raw material milling, because of the better suitability of the equipment to the materials, the electrical consumption of the workshop has fallen from 41 kWh/t to 34 kWh/t of raw material and in addition, production has increased from 110 t/h to 190 t/h. The specific overall thermal consumption has been reduced from 1035 Kcal/kg to 867 Kcal/kg which is essentially due to the recycling of air in the cooler to dry the raw material. Output has increased from 1570 t/d to 2400 t/d and in addition, the utilization rate of the furnace has increased by 25% (relative value). BUSSAC PLANT OBJECTIVES RESULTS IMPROVEMENT IN PREPARATION OF RAW ADAPTATION OF THE WORKSHOP MATERIAL – STOCK BELT –AEROFALL INCREASE IN CAPACITY PRODUCTION CAPACITY RAISED FROM 1500 T/D TO 2400 T/D IMPROVEMENT IN ENERGY PERFORMANCE ELECTRICAL GAIN IN RAW MATERIAL MILLING=25 %

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BUSSAC PLANT OBJECTIVES

RESULTS THERMAL GAIN: 170 KCAL/KG

5. THE CASE OF COUVROT The modifications to the COUVROT plant are very similar to those that have been made in BUSSAC on the kiln part since they consist of: 1 —replacement of the planetary cooler by a grate cooler with electrofilter 2 —the installation of precalcining in the preheating tower. The purpose of these modifications was: – mechanical reliability of the equipment, and we have spoken in connection with BUSSAC over the problems linked with the planetary cooler, – reduction in energy consumption, – and lastly, the increase in the production capacity. The ten cooling tubes in the POLYSIUS kiln have been replaced by a HITACHI BABCOCK cooler with a 108 m2 grate surface area. Secondly, the internal diameter of the body has been reduced from 5.6 m to 5 m in the burning zone. The DOPOL tower has been modified to insert a calcination chamber between turbulence chamber (cyclone 2) and cyclone 1 (20 to 25 % fuel). The consequences of these conversions are the following: – the specific consumption of the kiln has fallen from 911 Kcal/kg to 807 Kcal/kg and the overall specific consumption has fallen from 971 Kcal/kg to 909 Kcal/kg, – output has increased from 3800 t/d to 4200 t/d. The following stage in energy recovery will be drying the raw material by air from the cooler (and increasing the capacity). COUVROT PLANT OBJECTIVES RESULTS INCREASE RELIABILITY OF EQUIPMENT REPLACEMENT OF PLANETARY COOLER BY GRATE COOLER REDUCTION IN ENERGY CONSUMPTION SPECIFIC CONSUMPTION REDUCED BY 60 KCAL/ KG INCREASE IN PRODUCTION CAPACITY PRODUCTION INCREASED FROM 3800 T/D TO 4200 T/D

ENERGY SAVINGS IN CEMENT KILN SYSTEMS ERIK BIRCH F.L.Smidth & Co. A/S 77, Vigerslev Allé DK-2500 Valby Denmark

Summary In the context of ever more competitive markets for cement, the energy efficiency is an important parameter. Particularly in Europe the growth is insufficient to justify new plants as a means of obtaining better efficiency (and more capacity). The improvements possible on existing kiln systems therefore assume a greater importance. The paper outlines some of the methods available for optimizing existing kiln systems, with particular emphasis on the consumption of thermal and electrical energy. It is shown that substantial savings can be obtained by modest means. The importance of a thorough technical and economical evaluation is stressed and some simplified examples of savings are shown. 1. METHODS OF REDUCING THE ENERGY CONSUMPTION IN CEMENT KILNS Among the large variety of methods that may be applied to reduce the energy consumption of a kiln system, only the most commonly used will be discussed in the following. The method, of course, depends very much on the process considered and whether it is a question of a new kiln or an existing one. Furthermore, for the choice of method and its profitability it is important to ensure that the increased production can be sold. Before selecting a certain method, the circumstances of the process should, therefore, be elucidated.

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If it is a new plant, a large number of factors have to be considered, e.g. type of raw materials, their inherent humidity, transport facilities etc. Studies of the market in order to establish expected sales possibilities should be made before selecting the right process. Although this is a major and important subject it will not be treated further in this article, which will focus on the most profitable energy savings in existing plants. 2. DEFINITION OF PRODUCTION TARGETS The market, relations to possible competitors, available reserves in the quarry, the infrastructure, economical and political factors as well the price of cement, fuel and electrical energy must be evaluated carefully, and a production target should then be formulated. Generally, it can be said that energy savings alone seldom pay the investments herein, unless tax reductions or direct subsidy by the government or supranational organs can be obtained. The decision about a desired production based on the above considerations will then form the basis of the technical and economical considerations determining the choice of the optimum conversion. In order to estimate all this systematically, the costs per ton of cement should be calculated, for instance in the form of a work sheet on a computer. The entries should be reasonably detailed and expressed as a function of a mass and energy balance. For instance, the energy price can be split into contributions from all the departments of the plant, such as the crushing, raw mill, coal mill, kiln, cooler, and cement mill departments. The global effect of a modification of one item may in this way easily be estimated. 3. THE MASS AND ENERGY BALANCE In order to estimate the size of possible savings, the actual mass flows and energy consumptions must be known. The best tool for this is to prepare a mass and heat balance and then simulate the process with a view to identifying possible savings. The following considerations apply to the kiln department in particular, but some of the techniques are also applicable to other departments. The preparation af a heat balance takes as a starting point the measurement of the output by weighing of the feed or product, whichever can be carried out in the most exact way. Weighing of clinker is normally preferred. The input of fuel should also be weighed during the test period. For calculation of the radiation and convection losses, the surface temperatures must be measured on cooler, kiln and preheater. The temperatures of the surroundings, air velocities etc. should also be measured. The temperatures of in and outgoing flows must be measured, in particular clinker, smoke gas out of the kiln, excess air, air, raw meal and fuel. Samples of raw meal, clinker, dust, fuel and smoke gas out of the kiln should be taken for analysis purposes. Pressures (and underpressures) in the process should also be measured with a view to estimating the possibilities of obtaining savings in power consumption by reducing these pressure losses.

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Calculations and Analyses The details of these calculations will not be analysed here, but some examples mostly applicable to a four stage ILC-E kiln are given in the following. Thermal Energy Savings are mainly obtained by a reduction of radiation losses and false air amounts from direct or semiindirect coal mill systems, reduction of reaction heat, improvement of the cooler efficiency, additional cyclone stages, improvement of the cyclone efficiency and reduction of possible smoke gas losses due to injection of free water in the kiln system. Surface Losses An example of typical surface losses is given in Appendix 1, Table 1. The column marked NORMAL indicates the normal values and the column marked HIGH shows values corresponding to a highly insulated kiln system. The indicated radiation losses are 160 kcal/kg clinker for a normal IL-E-system and 123 kcal/kg clinker for a highly insulated system of the same type. The saving must be calculated by simulation in a computer program. Calculation of a heat balance for a typical system with the two sets of radiation losses is shown in Appendix 1, Table 2, and Appendix 2, Table 3, showing a saving of approx. 36 kcal/kg, which comes rather close to the saving in surface losses. The savings obtained are biggest where the surface loss is high, i.e. for kilns with tertiary air duct and calcinator. By the installation of a highly insulating lining in a preheater, a surface loss of approx. 600 kcal/m2/h can typically be obtained, corresponding to a 50 per cent reduction of the surface loss in relation to older preheaters with a poorer insulation. If an insulating lining is installed in the rotary kiln and the planetary cooler, 10–20 kcal/kg clinker can typically be saved. For the planetary cooler, however, this will normally result in a higher clinker temperature. 4. FALSE AIR INTAKE False air intakes at the kiln hood cause the biggest losses as these must be replaced by a corresponding quantity of hot recuperated air from the clinker cooler. It is therefore of great importance that the seals at the outlet are kept in the best possible condition. Unfortunately, it is often seen that the inspection doors and hatches are open, and in that case a saving may be obtained without any investment, just by ensuring that these are kept closed. The heat loss due to the false air intake here is approx. 1.6 kcal/0.01 kg false air. If approx. 0.1 kg/kg clinker is found as false air, an additional heat consumption of about 11 kcal/kg clinker is required, as the normal intake is approx. 0.03 kg air/kg clinker. In this connection it may be mentioned that primary air in excess of the required amount (approx. 10% with a modern Swirlax burner) must be considered to be false air.

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If the false air is added with the feed, the loss is considerably smaller, as it is made up of the required energy for heating of the false air to the outlet temperature plus a somewhat larger smoke heat loss due to the larger fuel and air consumption. A typical false air quantity by elevator transport of raw meal to the preheater is 0.02 kg/kg clinker and 0. 12 kg/kg by air lift. This results in an increased heat consumption of 1.4 kcal/kg clinker, corresponding to 0. 14 kcal/kg clinker/ 0.01 kg false air, or approx. 11 times less than the additional heat consumption for the same false air quantity at the kiln hood. 5. THE EXCESS AIR Some kiln systems have a relatively high smoke gas loss due to a high amount of excess air after the kiln and/or calcinator. This is often due to incomplete combustion of the fuel at a normal excess air quantity. In the kiln, poor flame formation is often the reason for that. An insufficient primary air quantity or velocity may cause coal to fall out of the flame. Too coarse coal meal (or too cold oil) may also result in CO formation. The cause must be found in each case before a solution can be given. A modern burner type with separate axial and radial air may often solve the problem. In the calcinator the high smoke loss may be due to coarse coal meal (or cold oil, which is poorly atomized), a too short gas retention time, uneven temperature profile in the calcinator or a too low combustion temperature. As above, a solution must be found after a thorough process study. The consequence of the mentioned high excess air quantities is reduced output, a higher heat and energy consumption and a higher gas load on filter etc. 6. DIRECT AND INDIRECT FIRING By direct or semi-indirect firing in kiln and/or calcinator the recuperated hot cooler air is replaced by relatively cold and humid air from the coal mill. The additional cost for the air will be almost as mentioned above for the kiln hood, but due to the high heat capacity of water vapour, the smoke loss increases considerably. The air quantity will typically be approx. 20–25% of air. (the required air quantity for combustion without excess.air), corresponding to approx. 0.22–0.28 kg/kg clinker. The normal quantity by indirect firing will be approx. 10%, corresponding to 0.111 kg/kg clinker. The additional heat consumption will be 18–27 kcal/kg clinker. The heat consumption increases approx. 3.9 kcal/kg clinker/0.01 kg water vapour, and if it is assumed that coal with Hi=6500 kcal/kg coal and a H2O content of 12% is used for firing, a vapour quantity of 0.0164 kg/ kg clinker is obtained at a heat consumption of 780 kcal/kg clinker, corresponding to an additional heat consumption of approx. 6 kcal/ kg clinker. The possible saving by changing from a direct to an indirect firing system will be in the order of 24–33 kcal/kg clinker. Besides, a better stability is generally obtained by indirect firing, as the kiln is isolated from the effect of the start and stop of the mill. It is difficult to calculate beforehand the saving from a greater stability, but it is estimated to vary between 5–25 kcal/kg clinker, dependent on the fluctuations in coal quantity for the direct firing. See Appendix 2, table 4 for a comparison of two typical systems, and Appendix 3, table 5 for a summary of savings in energy.

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7. CYCLONE EFFICIENCY The more efficient the cyclones in the preheater, the better the efficiency of the preheater. In this connection, the lowermost cyclone is the most important one as the material from this cyclone is partly calcined, and some of the dust that escapes to the second stage from the bottom will recarbonatize and liberate heat. A reduction of the 4th stage efficiency from 85% to 75% will typically result in a 9–12 kcal/kg clinker higher heat consumption. The increased recarbonatization may also cause the 3rd stage temperature to enter into an area where the risk of cyclone blockings increases. On the other hand, the effect of a deterioration of the efficiency of the top cyclone is not so important for the heat consumption of the kiln system. A reduction from 92% to 82% efficiency for stage 1 (the uppermost) gives an increase in heat consumption of approx. 3–4 kcal/kg clinker, which is of less importance in this connection. (It will, however, have an influence on the dimensioning of filter, dust transport and smoke gas fan and cause higher wear on the smoke gas fan.) As a central pipe is often missing in the bottom stage due to the high temperature, the efficiency of this stage is often lower than for the other stages. The installation of a triangular constriction may contribute to a better efficiency. In difficult cases special central pipes of ceramic material or special heat resistant steel may be recommended. To ensure durability of this central pipe it is often made as rings, each one suspended on the ring above. 8. COOLER LOSS When making up the heat balance of the kiln system, the cooler loss is determined. This loss is the sum of the heat in clinker, excess air and surface loss. The normal values are 130 kcal/kg clinker for a grate cooler and approx. 120 kcal/kg clinker for a Unax cooler (planetary cooler). These losses are standard values at a reference heat consumption of 780 kcal/kg clinker. At a higher heat consumption, the air consumption from the cooler increases, and the loss decreases. At lower heat consumptions the cooler heat loss rises, as a smaller part of the recuperated heat is utilized in the kiln system. By optimizing the cooler operation, 10–20 kcal/kg clinker can often be saved, dependent on the actual condition of the cooler. It will lead too far to enter into details here, but a couple of methods may be mentioned. The planetary cooler can be insulated and the lifter configuration can be optimized. In the grate cooler a thicker layer of clinker on the first grate can give better heat exchange. This requires a higher air pressure and sometimes, dependent on the arrangegement of the cooler, new partition walls under the grate with separate fans for the new chambers. Partial recirculation of hot, dedusted air to some of the chambers of the cooler may also improve the efficiency but this has to be paid for by a higher energy consumption for the fans.

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9. ADDITIONAL CYCLONES Depending on the need for hot kiln smoke for drying of raw materials in a raw mill or coal in a coal mill, more stages may be installed. For a four stage kiln with a heat consumption of 780 kcal/kg clinker, an improvement of approx. 16–20 kcal/kg clinker can be obtained by the installation of a 5th stage. This corresponds to a 35–45°C drop in the outlet temperature. With a modern, highly efficient low pressure cyclone the pressure drop will be an additional 50 mm VS (corresponding to approx. 0.5–0.6 kWh t of increased power consumption in the smoke gas fan). A 6th stage will save approx. 8–10 kcal/kg clinker and costs approx. 0.5–0.6 kWh/t more in power consumption. It rarely pays to install a 6th stage. 10. ELECTRIC ENERGY The consumption of electric energy in the kiln department generally amounts to 25% of the total energy consumption for the production of one ton of ordinary portland cement. The largest consumers are the cooler (if it is a grate cooler) including dedusting, the smoke gas fan, the kiln motor and the dedusting. To this must be added a number of smaller consumers such as the clinker crusher, clinker transport, raw meal transport to kiln, primary air fan, compressed air, etc. Smoke Gas Fan The power consumption of this fan usually amounts to between 6–14 kWh/t clinker. This may be reduced by various methods: By the installation of new cyclones with a lower pressure loss approx. 0.6–0.8 kWh/t can be saved (dependent on the efficiency of the fan) for each 50 mm VS the pressure loss is reduced. As many older cyclones have a pressure loss of 100–140 mm VS, approx. 0.6–1.1 kWh/t can be saved by the exchange of one top stage and a similar amount by the exchange of one bottom stage. (For construction reasons it is often difficult to exchange the intermediate stages.) By reduction of the false air quantity and a possible too large amount of excess air a good deal may be saved. Some old fans with straight, radial blades have efficiencies around 65–70%, and by replacement with a modern, highly efficient type with backward curved blades, between 15–20% of the power consumption can be saved. An exact calculation of the pressure losses in the system may reveal other sources of savings (for example superfluous tube bends, too sudden velocity changes etc.) Clinker Coolers For kilns with planetary coolers savings on the cooler are limited. In case of a high dust circulation between cooler and kiln, a reduction of the lifting capacity of the internals in the first part of the cooler so that that less dust is swirled into that zone gives some saving. This results in a lower degree of filling in both kiln and cooler with a lower power consumption as a consequence.

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For grate coolers there are more possibilities. A too thin layer of clinker often results in the requirement of more air for cooling due to the reduced efficiency. If there is a thicker layer of clinker, e.g. 500–700 mm on grate 1 and 25–350 mm on grate 2 and 3 (or additional grates) a better heat exchange is obtained and the desired clinker temperature may be reached with a smaller air quantity. Filter Installation If a bag filter is used for dedusting in the grate cooler by admixture of cold air to obtain the required temperature, more than 50% of the power consumption can be saved by the installation of an electrostatic precipitator, which filtrates hot excess air whereby cooling air can be dispensed with. In addition, the pressure loss through an electrostatic precipitator is only approx. 30% of the pressure loss in a typical bag filter. Alternatively, the air cooling may be replaced by an air to air heat exchanger, whereby an appreciable saving in power consumption can be obtained. A reconstruction like this will also reduce maintenance costs substantially. The power consumption for transport of aircooled kiln smoke through a bag filter can also be reduced considerably, for instance by the installation of a cooling tower with water injection instead of the air cooling. Also in this case the installation of an electrostatic precipitator can reduce the pressure loss by about 70% (corresponding to approx. 1–1.5 kWh/t clinker). 11. REPORTING When the plant has been studied according to the above-mentioned principles, a report must prepared, giving all measurements, analyses etc. The technical proposals and the resulting savings should then be stated. It is important that all savings as well as estimated expenses are given. If public authorities grant subsidies to energy saving measures, a very detailed and well documented report is almost always required. The environmental consequences should also be evaluated, as permission for reconstructions causing more pollution is very seldom granted. 12. PLAN FOR ACTION Based on the detailed technical report, various proposals can be analysed with a view to their economical consequences. The most advantageous proposals should be selected and submitted for approval and preparation of the final project. In this phase it is often important only to propose the possibilities where the biggest of savings can be obtained, thereby ensuring the profitability of the project. If all possibilities are included, the less profitable modifications will often conceal the profitable ones with the result that in the worst case the project will not be carried out and in the best case a new project will have to be prepared. If time and resources are available, alternatives might be worked out.

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13. SUMMARY When energy saving projects are treated, these have to go through four main phases: The study and analysis phase where the possibilities are explored. The proposal phase, where the best ideas are transformed into concrete plans. The decision phase where the project is evaluated and it is decided whether to continue or to repeat phase 2 (or to shelve the project). The execution phase, where the plans adopted are carried out. Experience shows that it is important not to omit any of the early phases, particularly if subsidies are desired, since public authorities generally demand very exact documentation.

Appendix 1

TABLE 1 TYPICAL RADIATION LOSSES

Insulation Preheater with 4 stages and ILC-E calciner Kiln without precalcination Precalciner kiln Grate cooler and kiln hood Planetary cooler

kcal/kg clinker

kcal/kg cl

Normal 25 50 40 6 85

High 15 38 28 6 70

TABLE 2 HEAT BALANCE Normal losses

kcal/kg clinker

Heat loss in smoke and dust ” ” due to radiation from preheater ” ” ” ” ” ” ” kiln Reaction heat of mix Evaporation of water Radiation loss from cooler (planetary) Heat content of clinker “Free” heat input with air, raw meal and fuel

185 25 50 385 5 85 49 −31

121

Normal losses

kcal/kg clinker

Net heat consumption of kiln

753

Appendix 2

TABLE 3 HEAT BALANCE Low losses

kcal/kg clinker

Heat loss in smoke and dust ” ” due to radiation from preheater ” ” ” ” ” ” kiln Reaction heat of mix Evaporation of water Radiation loss from cooler (planetary) Heat content of clinker “Free” heat with air, raw meal and fuel Net heat consumption of kiln

178 15 38 385 5 70 56 −30 717

TABLE 4 TYPICAL HEAT BALANCE (Ref. temp. 0°C)

Heat in kiln gases ” ” by-pass gases Radiation from preheater (precalciner) Radiation from kiln

kcal/kg direct indirect

clinker

239 15 36 40

196 15 36 40

123

Tertiary air to coal mill Heat loss from clinker cooler Reaction heat “Free” heat Net heat consumption of kiln system Gas temp, after preheater, °C Gas volume Nm3/min. ” ” m3/min. Underpressure after preheater Consumption of electrical energy for preheater ID-fan Coal consumption, 10% H2O, t/d

kcal/kg direct indirect

clinker

8 152 395 −36 849 380 3420 8230 960 13.6 446

8 148 395 −33 796 350 3080 7030 700 8.5 418

Appendix 3

TABLE 5 TYPICAL EXAMPLE OF ECONOMICAL SUMMARY OF COST OF ENERGY (refer to Table 4) Saving in Energy Cost Basis: Power cost: 0.06 USD/kWh Coal ” : 50 USD/MT coal Production: 3000 MT clinker/dry Operation: 330 days/year Saving in Electrical Energy Cost 0.06×3000×(13.6–8.5)×330 Saving in Fuel Cost 28×330×50 Total Energy Saving

=302,940 USD/year =462,000 USD/year 764,940 USD/year

or, instead of saving electrical energy, the production could be increased by 500 MT/day.

HIGH ENERGY SAVINGS THROUGH THE USE OF A NEW HIGH-PERFORMANCE HYDRAULIC COMPONENT THE K-TECH PROCESS M.PALIARD and M.MAKRIS CLE Tour TECHNIP 170, place Henri Regnault 92090 PARIS LA DEFENSE Cedex 23 FRANCE and G.MENARDI and M.BAILLY CIMENTS DE CHAMPAGNOLE Boite Postale 339 39104 DOLE Cedex FRANCE Summary A new hydraulic binder, based on an active synthetic component burnt at low temperature under controlled atmosphere has been developped. In view to optimise energy savings resulting from this new product, a specific equipment has been designed to burn the active component starting from a dry raw-meal. The production rate of the new facility is of 300 mt/day and the heat consumption is lower than 350 th/mt. 1. PREAMBULE Research work on energy savings made by Société des Ciments de Champagnole since the beginning of the 80’s has resulted in the development of a new type of hydraulic binder, based on an active synthetic component burned at low temperature. The process which consists in mixing the active component (the kalsin) with Portland clinker was patented in 1984. The industrial development of this patent results from the joint venture between SCC and CLE, which teamed up for this project within the G.I.E. “CLE-CHAMPAGNOLE” between 1986–1989. The main objective of the project was the design and construction of an industrial and experimental burning line specifically suited for the production of the active base (kalsin) under optimised energy saving conditions.

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In December 1986, CLE-CHAMPAGNOLE was granted financial support by the Agence Française pour la Maitrise de l’Energie (French Agency For Energy Savings) for the implementation of the project to the tune of 30 % of the budget forecast. After 2 years of continuous effort, the outcome is a great technical success: the construction of the burning line was completed in late April 1988. Start-up and industrial tests were conducted in 1988 and during the first half of 1989. The production of the prototype facility is now integrated on a full industrial scale at the Rochefort Cement Plant. 2. DESCRIPTION OF THE K-TECH PROCESS The patented process (European Patent N° 8410186) on which the K-TECH process is based consists in producing an active synthetic base through thermal activation under controlled atmosphere of clayedcalcareous material of specific composition and in producing hydraulic binder by mixing that base with Portland cement clinker or other activators. Under the specific conditions of the burning process, it is possible to combine, on solid state reaction basis, acid component of the raw mix with part of the lime of the carbonates. These reactions produce silicates, silico-aluminates, aluminates and ferrites while a proportion of carbonate is maintained without thermal dissociation, hence without formation of free lime. The burning operation which is conducted under strictly controlled conditions regarding temperature, retention time and partial CO2 pressure leads to a product (the kalsin) that features a neoformed phase, an activated carbonated phase and low free lime content likely to develop outstanding hydraulic and mechanical properties in the presence of a given quantity of clinker. The industrial burning unit allows the processing of raw meal on a dry basis system which meets the above constraints. The raw material consists of either a single natural material or a mixture of 2 or 3 components. A large range of raw material can be used in this process such as marl, clay, limestone, industrial by-products, etc. The reactivity of the kalsin and the burning conditions are closely linked with the chemical and physical characteristics of the raw mix. The reactivity of the suitably ground material in the presence of an activator likely to free calcium ions during hydration, such as clinker, results from: – the mineralogical composition of the neoformed phase which contains Belite, gehlenite, aluminates and ferro-aluminates, ferrites and lime-undersaturated silico-alumina compounds, – the micro-structure of the neoformed phase which is desorganised or presents deformed lattice. – the carbonated phase which is thermally activated during the burning operation and maintained without thermal dissociation, – the large specific area of the material which is reached after moderate grinding. K-CEM BINDERS K-CEM binders may consist of a mixture of kalsin and clinker with a suitable quantity of gypsum and minor additives.

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127

As an indication, possible binary mixtures which can be classified as customary hydraulic binders cover a broad range from 0 to 80 % kalsin. The mechanical performances of binders, directly related to the kalsin proportion, also depend, as for all clinkers, on the raw mix chemical and physical characteristics and on the burning conditions. The following table gives for ISO mortar, the average performances reached by binders with different kalsin contents. Their compression strength is expressed in MPa (Mega Pascal or N/mm2). DAY

KALSIN 30 % CPA55 R 70 %

KALSIN 50 % CPA 55 R 50 %

KALSIN 80 % CPA 55 R 20 %

2 7 28 90 % T 28

20–25 30–42 45–55 50–61 80–99

15–20 30–36 40–50 45–55 70–85

5–12 18–25 30–45 35–48 55–80

% T 28: % of the unsubtituted cement strength at 28 days.

3. BURNING LINE 3.1. KCC—Burning process The challenge of the new installation was to recreate in a suspension reactor, reaction conditions close to those prevailing in the rotary kiln (figure 1). Before the construction of the present unit, tests were made in fluidized and suspension reactors of pilote scale. The conclusions were the following: – direct suspension reactors don’t allow for sufficient confinement of the material. – fluidised bed reactors require a high CO2 content gas for primary fluidisation, and coal combustion is severely affected. The present calciner (KCC) has so been developped to allow for coal combustion in a “free” zone and for confinement of material under high CO2 pressure level. Preliminary studies have shown that better results were obtained if the material could be quenched under moderated CO2 pressure level. For optimisation of energy consumption, recovery of sensible heat of combustion products and kalsin is carried out in a suspension heat exchanger (figure 2). 3.2. KCC—Burning line General views of the 300 T/day industrial equipment in the S.C.C.’s Rochefort Plant are presented during erection (figure 3) and after completion (figure 4).

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The control of the KCC burning line is fully automated and the new unit is jointly operated with the kiln and the two grinding shops of the plant by a working shift of three operators. Figure 5 is a view of the control panel of the KCC burning line in the Rochefort Plant Control Room. 3.3. Process performance During industrial production of the kalsin in the new installation, it has been observed that the reactions of the installation to variations of raw meal flow rate or combustible flow rate for short periods of time didn’t affect the performances of the calciner. Heat and power requirements are listed in the table (1) for present conditions in the industrial unit of SCC in ROCHEFORT (FRANCE) and as projected for future implementations. 3.4. Pilote equipments In close relation with industrial process, laboratory pilote equipments have been developped to test reactivity of various raw meals on samples of less than 100 kg (figure 6). 4. TECHNICAL FEASIBILITY The production of active base (kalsin) is possible with many natural raw materials used in cement manufacture. Like for cement, their chemical and mineralogical composition determine the reaction kinetics during burning. The implementation of the process requires a feasibility study based on pilote scale production tests. CLE-CHAMPAGNOLE is equiped to perform such feasibility study from raw materials to finished products. 5. ENVIRONMENT The K-TECH process through the reduction of clinker amount in the binders and due to the low burning temperature of kalsin, leads to an important reduction of CO2 and NOx emissions. 6. CONCLUSIONS The new K-TECH process industrial application by CLE and CIMENTS DE CHAMPAGNOLE at the ROCHEFORT plant (FRANCE) constitutes a major improvement in the composite cement technology. Its main impact related to energy savings is summarised in figures 7 and 8. New perspectives are also opened by the K-TECH process for: – production increase at low capital cost – diversification and flexibility in the production policy

HIGH ENERGY SAVINGS

Fig. 1. K-Tech burning line

– environmental protection. TABLE 1. KCC burning line performances PRODUCTION RATE HEAT CONSUMPTION POWER CONSUMPTION GRINDING RAW MEAL AND KALSIN

Present Up to Present Down to Present Down to Present Down to

300 T/J 300/350 Th/h 18/20 kWh/t 35 kWh/t

1200 T/J 280 Th/h 15 kWh/t 25 kWh/t

129

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 2. K-Tech-KCC burning line

HIGH ENERGY SAVINGS

Fig. 3.

131

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 4.

Fig. 5.

HIGH ENERGY SAVINGS

Fig. 6. K-Tech burning process pilot stage

133

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig. 7.

HIGH ENERGY SAVINGS

Fig. 8.

135

ENERGY MANAGEMENT IN THE U.K. CEMENT INDUSTRY Dr T M Lowes, Energy Manager Mr K W Bezant, Technical Services Director Blue Circle Industries PLC Technical Services Division 305 London Road Greenhithe Kent DA9 9JQ

Summary Information is given on the energy consumption of the U.K. Cement Industry and with reference to Blue Circle Cement how the costs and consumption have varied over the last 30 years. Details are given on the approach in BCC to Energy Management. Recent achievements in energy reduction via the development and application of flame, milling and expert system technology are highlighted. Plans for energy cost reduction in the future, are outlined with reference to the Department of Energy’s assessment of the potential for energy reduction in the Cement Industry. 1. BACKGROUND As a consequence of the chemical reactions and physical operations involved, the cement manufacturing process is a high energy user. The reactions necessary to produce the mineral structure of cement take place at a high temperature in the range 1400 to 1600°C. To ease these reactions, the raw material has to be very finely ground. The cement clinker produced by this pyroprocessing also has to be ground to a very fine state —in order to yield the strength development characteristics needed in a good concrete. The current UK cement production of approximately 15 million tonnes per annum, has an electricity energy requirement in excess of 2 TeraWatt hours and at approximately 2 million tonnes per annum is the largest user of pulverised coal in the private sector. The overall energy bill is in excess of £150 million and represents approximately 40% of production costs. Hence, energy management is an important discipline in the Cement Industry.

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Cement making processes can be divided into two broad categorie— the wet and dry processes. The two major intermediate variants are the semi-wet and the semi-dry processes. All four of these methods are currently used in type of process used has an important bearing on the amount and form of energy required to produce cement clinker. Table 1 shows a typical breakdown of the distribution of energy consumption in the manufacture of cement. This shows that while there is lower fuel consumption in the dry process due to the lower evaporative load, a higher electrical consumption is encountered, due largely to the dry raw material preparation (grinding, pneumatic conveying and blending) being more energy intensive. TABLE 1—TYPICAL ENERGY CONSUMPTION IN CEMENT MANUFACTURE (KWH/TONNE)

Raw material winning and preliminary crushing Raw material fine grinding and blending Coal preparation and firing Kiln system (ID fan and cooler) Dust collection Cement grinding Despatch Total electric power Kiln fuel

(1384 kcals/kg)

WET PROCESS

DRY PROCESS

3 10 10 25 8 45 8 109 1610 1719 ====

4 44 6 23 6 45 8 136 998 1134 ====

(858 ks/kg)

The major area of energy consumption, whatever the process, is the heat treatment of the raw materials to form the clinker, which is subsequently finely ground to produce cement. However, the energy consumed during cement grinding and in dry raw material preparation is also extremely significant. Table 2 shows the contribution of Blue Circle Cement’s fuel and power to its production costs over a thirty year period. The level of total energy used—up to 50% total production costs—stimulated an initiative to reduce consumption long before the OPEC driven escalation in energy costs of the ’70s. Modern management techniques are naturally applied to all resources, and with energy being such a high percentage of costs, it has always been at the top of the priorities. Blue Circle appointed its first Energy Manager in the ’20s when coal was only five shillings a ton. TABLE 2—BLUE CIRCLE CEMENT PRODUCTION COSTS TOTAL

FUEL

1955 100 41 1965 100 31 1975 100 25 1985 100 31 Note: Delivery cost add approximately 33%

POWER

WAGES

DEPRN

OTHER

13 13 16 14

16 19 22 18

10 8 15 13

20 29 22 24

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

FIG. 1 BLUE CIRCLE CEMENT

Figure 1 shows how Blue Circle’s fuel consumption has generally dropped over the last 15 years (some increase after 1984 being due to the use of adverse quality fuels during the miners’ strike). Figure 2 shows that a similar trend has not been achieved in electrical energy consumption. This has been due principally to the extra electrical power required to operate Works at lower feed moistures more than offsetting gains that have been made through more efficient power usage. The more recent steep increase is due mainly to finer grinding being employed in order to meet the demand of the concrete industry for higher strength levels. Improved cement milling efficiencies have reversed the trend and the current (1988/ 89) increase in the UK cement market has resulted in some reduction of the excessive strength levels of Ordinary Portland Cement resulting from over-capacity and common pricing (now terminated). Hence, the 1989/90 kWh/tonne will again be lower. The reductions have been achieved by ensuring that appropriate effort has been put into the important areas associated with energy conservation, namely: Good Housekeeping, Application and Existing Technology and the Development and Application of New Technology. Each of Blue Circle’s 12 UK Works has an Energy Management Plan, covering both energy consumption and cost for the current and future years. This is backed by strong Main Board and management commitment to achieving energy savings by budgeting, monitoring and judicious capital investment. Figure 3 shows the relative change in the RPI and in the prices of cement, electrical energy and fuel over the last 20 years. Due to these trends, energy costs have remained a similar percentage of total production costs, despite significant reductions in average fuel consumption. An increase in the cost of fuel and energy in recent years at a similar rate to that experienced for fuel costs, together with a virtually static cement price —4.5% increase from 1982 to 1987 —would have reduced operating profits to an unacceptable level, as the extra costs could not have been passed onto the customer. These average energy costs have been reduced by a combination of improved supplier’s efficiency, negotiation, QUICS and optimum use of tariffs. Thus, a ) to the Cement Industry as a prelude to proportion of the recent increases in electricity prices ( Privatisation, will have to be passed onto the customer.

ENERGY MANAGEMENT IN THE U.K. CEMENT INDUSTRY

139

FIG. 2 BLUE CIRCLE CEMENT

Until recently the UK and general world cement market has remained largely static. Therefore, to maintain a viable cement business, operating costs have had to be minimised. Unfortunately, in the UK the cost of building a new greenfield site dry process works (e.g. £150M for an annual capacity of a million tonnes of cement) does not meet acceptable investment criteria, so that the approach of using an entirely new process design to reduce energy consumption has not been viable. Thus, in practical terms, energy consumption can only be reduced via cost-effective modifications to existing Works and the development and application of novel technology, backed by effective energy management techniques. A similar situation will exist in the future unless the current upturn in the market creates a permanent requirement for a higher UK production capacity. Blue Circle has over 50% of UK cement sales. A significant part of the current national approach to reducing energy costs can therefore be readily outlined by reference to Blue Circle Cement’s own activities. 2. ENERGY MANAGEMENT Within Blue Circle Cement, Energy Management incorporates both the cost and specific consumption of energy. Each Works has an annual target of specific fuel (kcals/kg) and electricity energy consumption (kWh/ tonne). Progress against target is monitored weekly on the Works and monthly by the Chief Executive. Online monitoring is used as appropriate, bearing in mind that all the fuel is pulverised coal and the product is either clinker or cement, none of which can be accurately weighed on-line with existing equipment. Inferential computer-based techniques have been developed to overcome the problem. On the Works the energy consumption is divided into a range of departments, each with its target and appropriate monitoring activities. The targets are set by the Technical Centre in conjunction with the Works and is based on experience and what is theoretically/technically possible for the plant. Maximum effort is made to ensure

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FIG. 3 BLUE CIRCLE CEMENT

that the Works’ team is aware of their targets and what they can do to meet them. Techniques have been developed by which the Works’ performance can be compared, even when the plant or process is different. Each Works has a long term energy reduction plan, where key technological improvements have been identified, evaluated and broadly costed in conjunction with the Technical Centre. These are reviewed with the Energy Manager on an annual basis. Items are then included in Blue Circle’s capital plan when appropriate. Coal purchasing is negotiated centrally but no negotiation is yet possible on Electricity Tariffs. The Works and the Technical Centre are continually looking at the possibility of using lower grade fuels and optimising the use of the CCL and Load Management Tariffs to ensure that the lowest average unit price is achieved. Blue Circle Industries’ position as a major International Cement Manufacturer and Consultant, ensures that its UK base—Blue Circle Cement—is energy efficient and capital investment is made judiciously. 3. THE WAY AHEAD The potential for the reduction of specific energy consumption in the Cement Industry can be most conveniently described in relation to the recent DoE evaluations and projections of the impact of a range of energy conservation possibilities, which are reproduced in Table 3.

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141

Table 3—ASSESMENT OF THE SAVING PENETRATION AS A PERCENTAGE OF CURRENT ENERGY USE (DoE)

1. 2. 3. 4. 5. 6. 7. 8.

EFFICIENCY MEASURES

1990

2000

FUEL SAVINGS

+ Wet to semi −wet conversions Wet to dry conversions + Improved combustion control + Wastes as fuel # Blended cements + Improved kiln insulation # Improved grinding technique # Waste heat utilisation * Total Saving

8.0% 4.0% 2.0% 2.5% 1.0% 3.0% 0.3% 2.5% 21.1% (595,000 tce/a)

8.0% 12.0% 2.0% 5.5% 3.5% 3.0% 0.7% 5.5% 34.1% (960,000 tce/a)

Coal Coal Coal Coal All Coal Electricity Electricity and Heating Fuel

+ Funded projects # Required projects for ECDPS package PROCESS CONVERSION (1, 2)

Recently, Blue Circle Cement have converted two wet process Works to semi-wet operation and two semidry Works to dry process/ pre-calciner operation at a total cost of over £100 million, with projected fuel savings of 20% and 15% respectively. Also, a number of small wet process kilns have been taken out of service. No further conversions are planned at the moment. IMPROVED COMBUSTION CONTROL (3)

Blue Circle’s projections indicate that, in the absence of a major capital investment, its main energy reductions in the next few years will result from applying recently developed technology. This technology is associated with flame design and high level kiln control, together with the planned maintenance and appropriate energy management techniques needed to achieve steadier lower energy operation. Fuel savings of up to 10% as well as a reduced NOX emission, have been demonstrated for the use of flame design techniques to eliminate reducing conditions in the clinkering zone of a kiln, coupled with mini computer based high level linguistic control of combustion and kiln operation to produce an optimally processed clinker. In addition, a more reactive cement is produced, steadier running is achieved and an improved refractory life can be expected. This development has been assisted by funds from both DoE and DoTI and is currently being extended to all Blue Circle Works. The system is now operating successfully on 5 of Blue Circle’s 12 Works, a further 3 are planned for 1989/90. WASTES AS A FUEL (4)

The use of wastes as a fuel offers a great potential to reduce prime fuel consumption. At its Westbury Works, Blue Circle Cement has used pulverised municipal refuse to replace up to 20% of its coal. This development —which has been assisted by DoE funds—can potentially be repeated on most Works in the country. However, while the technology now exists to replace the prime fuel by municipal refuse, it needs capital investment to be applied. The financial investment criteria required to make this attractive to both local authorities and cement makers are not generally achieved, due principally to the availability of adequate landfill sites in most areas. There may also be a reduction in production capacity as a result of using lower grade fuels, which is costly when full output is required to meet demand. The use of gas generated from domestic

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

waste used as quarry fill has been developed, as in the brick making industry, and is being used to replace up to 40% of the prime fuel on Swanscombe Works. Increased Environmental Regulations relating to the disposal of industrial wastes in the 1990s, will create an opportunity for the Cement Industry to use processed waste oils and solvents at up to 25% prime fuel replacement. However, care must be taken as the water and minor chemical constituents increase fuel consumption and reduce plant output and running time. BLENDED CEMENTS (5)

The introduction of blended cements—more commonly referred to as composite cements—using pfa, slag or calcite fillers offers an opportunity of reducing the amount of fuel required to produce unit weight of ‘cement’. Composite cements are generally available in Continental Europe. However, the cement produced has different characteristics and these have to be accommodated in concreting practise. BS12—the British Standard which specifies the majority of cement made by the Works and used in practise—does not permit the incorporation of these materials. However, from 1992 there will be a common European standard, covering the production of a range of cement types, which can include different fillers. With the 5% addition of a filler into OPC, the 3.5% energy saving estimated by the DoE should be achievable. IMPROVED KILN INSULATION (6)

Insulating refractories are used extensively in parts of the kiln system, especially the static preheaters. However, at present, high temperature insulating linings in the kilns have not been satisfactorily developed. Heat losses due to kiln re-heating, following stoppages due to failure of refractory or of ancillary plant, are the major current concern and this is subject to considerable investigation. Improved insulating refractories for high temperature zones—when developed—will undoubtedly result in an energy saving, providing no reduction in operational life is encountered. IMPROVED GRINDING TECHNIQUES (7)

Application of ball mill simulation techniques is achieving up to 20% reduction in energy consumption on Blue Circle’s current mix of open and closed circuit cement mills by optimisation of the media grading, diaphragm operation and cement residence time. New technology involving, roll press, roller mill and efficient separators offer the possibility of reducing the energy consumption for cement milling by up to a further 20%. Blue Circle are currently installing more efficient separators where an appropriate financial case exists, after the performance of the existing systems have been optimised. WASTE HEAT UTILISATION (8)

Evaluation of the potential to use waste heat from the process to generate electricity, has shown that use of the appropriate Rankine cycles could allow up to 20 kWh/clinker tonne to be generated from the cooler and preheater exhausts of an existing four stage dry process kiln system. Generally, the projected financial return makes the possibility only viable for a new Works where no other use has been found for the surplus heat. The most appropriate approach for all Works is to minimise the waste heat produced; this makes the prospective use of waste heat for power generation even more uneconomic. However, the forthcoming Privatisation of the Electricity Supply Industry may change the economics in terms of the financial benefits of having in-situ generating capacity. Power generation at the 10 kWh/tonne level using the ORC coupled to the cooler exhaust may become economic.

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In Blue Circle Cement the application of energy cost reduction techniques is strongly backed by the Main Board. Works’ Management are committed to achieving projected reductions aided by Technical Centre resources. The application of the two recent developments— items 3 and 7—are and will have a signficant impact on the energy efficiency operations in a cost-effective manner, with early paybacks. The computers installed for the high level kiln control are also being used to enhance the Works’ energy management via good housekeeping. On some Works, reductions in total fuel and electrical energy consumption of at least 10% should certainly be achievable by the start of the next decade. The adoption of a similar strategy by the rest of the cement sector, should result in at least similar nationwide levels of improvement in energy consumption. Future scenarios project a low energy consumption, minimum manned cement works with almost complete computer control via novel sensors for the on-line control of raw material/clinker characteristics. Blue Circle are already well down the path with the development of high level control and the introduction of Integrated Working. 1992 will reduce the average fuel consumption per tonne of ‘cement’ sales, by extending the use of composite cements. However, the increasing pressure of the Environment, which is loosely associated with 1992, in terms of dust, NOx and SO2 emission, will increase both fuel and electrical energy consumption as well as operating costs. The forthcoming Privatisation of the ESI will have a tendency to reduce electrical energy consumption if Regulation does not stop their rapidly spiralling charges, due to to marginal investments becoming more viable. There is much to be done and the Cement Industry has the will and economic drive to do it. DoE target of 34% savings in energy by the year 2000 identifies the potential for great rewards. However, a stable economey and low interest rates over an extended period are needed for investment in long life, capital intensive plant.

“WASTE GAS HEAT RECOVERY IN CEMENT PLANTS” MARQUES NETO General Manager of Souseias Cement Plant CIMPOR, E.P.

1. INTRODUCTION With the current available technology for cement manufacturing, the burning phase is, as well known, and among all the others integrating the process, the one which Involves a greater energetic consumption, namely for the effect of Its thermal component. It is also known that, in the convential dry-process clinker manufacturing lines, with kilns of medium or large capacity, and with pre-heater towers where raw-materials are presented with low moisture (and therefore with small consumption of kiln gases for drying) there will be considered amount of hot gases available from the burning process—as well as from the clinker cooling, when performed on grate coolers— that will be thrown off directly into the atmosphere with the energetic profit. Due to these facts, and since few years ago, several companies (In Europe and in Japan) decides to study this situation of “thermal waste”, and looked for economical solutions to take some profit of this energy, one of them has been designated as “Cogeneration”, meaning the production of electricity from the heat wasted In the burning process. In fact, with crude raw-materials of about 5% moisture contents, a dry-process burning line, with a kiln of medium capacity (1600 t/day), 4 stage pre-heater tower, and grate cooler, enables a production of electric energy of nearly 30 KWh/ton of clinker, from a turbo-generator set which turbine receives the steam produced, in suitable boilers, by effect of the hot gases of the burning process and hot air of the clinker cooling. The researches have also pointed out that the “waste heat recovery project” is only profitable when one is faced with great energy consumptions together with high cost of the unit electric energy.

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2. THE EXISTING CONDITIONS IN SOUSELAS PLANT OF CIMPOR JUSTIFYING A WASTE HEAT RECOVERY PROJECT The cost of the electric energy for the cement industry in Portugal is higher than in the majority of the european countries. According to the CEMBUREAU, and taking as reference the average cost of the KWh in Portugal (presently of about 10$00, equivalent to 0,0572 ECU), It will cost: – – – –

about 80% in England, Greece, Spain and Switzerland; about 67% in Ireland, Luxembourg, France and Denmark; about 54% in the Netherlands; about 43% in Sweden and Norway.

The Portuguese power-producing system, ran by EDP/Public Company presented, in 1989, the following power features: POWER STATIONS

Power (MW) Max. Guaranteed Power Peak Consumption

Run-of-the river 1660 (MW) (MW)

Hydro-storages 988 3897 4390

Thermal 2129

So, there are shortage power situations, compensated by the importation. With such a typical system, and not being foreseen on the near future the nuclear power production, one will not be certainly expecting in the meantime, in Portugal, a change on the actual (high) electric energy cost. Even considering the propitious “apport” of the recent decision of the Portuguese Government, the stimulation of the production of the electric energy by the private sector, will not change this trend. If, with the external envelopment, we consider the evolution of the inner costs at Souseias Cement Plant, the following may be stated: – During 1980/85, the total energy (thermal and electric) represented between 58% and 54% of the cement production costs, with the following distribution: . electric energy, between 13% and 15%; . Thermal energy (fuel-oil), between 45% and 49%; . variation of the cost of kwh in this period, from 2$04 to 7$91 (increased about 4 times) – From 1985 until the end of the 1st. semester of 1989, the total energy (thermal and electric) represented 48% to 44% of the cost of the cement production, with the following distribution: . electric energy between 20% and 24%; . thermal energy (coal), between 28% and 20%; . variation of the cost of the kwh, in this period, from 7$91 to 9$88 (increased 1,25 times).

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The change of the fuel in kilns, from fuel-oil into coal, at the Souselas Plant, from 1986 on, set off the cost of the product, which became equivalent to its thermal component. Considering that Cimpor’s factory at Souselas has an installed capacity of 2 million cement tons, which represents electric energy consumptions of about 200 GWh per year, and due to the high cost of the kwh supplied, thus are assembled all the economical conditions for the development of a “waste heat recovery” project in this plant (great consumptions, very expensive electric energy). In this sense some specialised companies in this matter have been contacted, being elected NIHON CEMENT COMPANY (NCC), a Japanese Company from Tokyo, with well succeeded experiences in this field. Based on a preliminary study developed together by NIHON, 1ST (Engeneering Faculty of the Technical University of Lisbon) and CIMPOR itself, the project “Waste Heat Recovery in Cement Plants” has been presented to the Commission of the European Communities on April 1988, as an Energy Demonstration Project to be installed in Cimpor (at Souselas Cement Plant). Later, in November, a subsidy on the amont equal to 30% of the project’s cost had been conferred by the Commission. 3. BRIEF DESCRIPTION OF THE PROJECT In what concerns the Project, Souselas Cement Plant has 3 clinker production lines, which main characteristics are as follows:

Start up of the production (year) Kiln capacity (t/day) Size of the kiln (ø×lenght) Pre-heater tower

Line 1 1974 1600 4,6×70m 4 stages

Line 2 1975 1600 4,6×70m 4 stages

Cooler

Grate

Grate

Line 3 1982 3500 5×75m 4 stages (Dopol) Satelite

The project comprises the Installation of 3 “SP” boilers close to the pre-heater towers of each kiln and 2 “AQC” boilers close to 2 grate coolers, where steam is poduced due to the passage of hot gases coming from the pre-heater tower (inside the “SP” boilers) and to the hot air coming from the coolers (inside the “AQC” boilers). The steam is supplied to a turbine-alternator set, producing electric energy, for a foreseen effective power of 8100 KW, and an annual production of 58 GWh. Equipment details, as well as the energetic balance of the project shall be object of a specific address from NIHON CEMENT CO. This project does not aim at either an increase in the cement production, or a change in the quality of the manufactured products. 4. ECONOMIC AND FINANCIAL OUTLOK OF THE PROJECT. TIMING. 4.1 The Project foresees, considered the values when presented to the Commission (April 1988), the following cost distribution: Boilers (5 units) ...........….

1100

Million

Escudos

WASTE GAS HEAT RECOVERY

Turbine and auxiliary equipment........................ Electric equipment.............. Erections........................ Civil works.......................... Various........................... Tests and measurements...........

250 220 220 210 100 10 2110

” ” ” ” ” ” Million

147

” ” ” ” ” ” Escudos

The Project will be financed through Cimpor’s own funds, completed by 2 subsidies, one from EEC and another from the Portuguese Goverment, with the following distribution: Cimpor’s own funds.............. 1578 Million Escudos EEC subsidy...................... 432 ” ” Port.Govern.subsidy.............. 100 ” ” 4.2 For the foreseen annual production of about 58 GWh, the value of this energy if acquired from EDP, at 1988 prices, would be approximately 580 million Portuguese Escudos; being the cost of exploitation foreseen for those 58 GWh (including all investment costs) of about 177 million Portuguese Escudos, the project’s “pay-back” is of about 5 years (it will be 4 years if one considers only the investment cost supported by Cimpor). 4.3 The project shall be performed in 4 phases, planned in the following way: Phase 1: Phase 2: Phase 3: Phase 4:

Project execution and tendering—Till the end of May 1990 (it is foreseen to sign the “turn-key” contract with the supplier on that date); Fabrication and Erection—From June 1990 until the end of 1991; Training and Commissioning—From October 1991 until March 1992; Test and Measurement (Demonstration phase)—From April 1992 until the end of March 1993.

Phase 1 is running at present, and we can say that there are no delays with Project so far. We are convinced that this Project will represent an important contribution to the saving of energy, either in strict business terms, or in terms of Country. And we sincerely hope that, through this one, other so valuable projects shall be able to fructify within the community space where we all are integrated.

DISCUSSION

TO: MR BLANCK MR S I NYAGBA, Benue Cement Co Ltd, Nigeria QUESTION What information would need to be input to achieve the long-term projected savings? ANSWER Initially we record all the energy consumption levels and then store them in a data base. From this we compare energy consumption with output, operators and any other relevant criteria. MR NOHLMANS, Novem, Netherlands Agency for Energy QUESTION We are using a computer to compare predicted (target) consumption with actual consumptions. Sometimes we find we have too much information; how do you suggest this is overcome? ANSWER To do this you need to reduce the data but enhance the information. The operator needs short-term information so that he can react and make the necessary changes to maximise energy efficiency. TO: MR DUMAS AND MR CASSOU MR J F SOARES, Cimento CAUE SA, Brazil QUESTION How long did it take to convert the grate cooler? ANSWER Between two and two and a half months.

DISCUSSION

MR FUKUSHIMA, NCC, Japan In connection with the free lime analyser, how often do you analyse free lime? ANSWER Twice every hour. QUESTION Where do you set up this monitoring instrument? ANSWER The sample is taken at the outlet of the kiln before the cooler. QUESTION Does the expert system work effectively using the free lime analysis data? ANSWER The expert system is linked to the control and command system already installed and the set points are modified using data from the free lime analysis. MR MENDONCA GOUVEA, Alsthom International, Portugal QUESTION What was the role of CITEC in the modifications described? ANSWER CITEC contributed with the design of modifications and consulted with manufacturers. TO: MR BIRCH DAVID HASPAL, ‘Linkman’ Image Automation, United Kingdom QUESTION Regarding going from direct to indirect firing, saving 25 kCal/tonne, could you comment on the extra cost of running indirect systems like the replacement of the firing pipes and the extra electrical energy required for the fans. These costs may offset some of the savings claimed. ANSWER Exact figures are not available. As you say, there are not only benefits there are some costs which should not be ignored. TO: MR PALIARD and MR BAILLEY QUESTION Has your material achieved full technical acceptance in France? ANSWER The cement is used in road making and other areas where its properties are acceptable. TO: DR T LOWES—No questions. TO: MR TAKAKUSAKI MR STEINBISS, KHD, BR Deutschland QUESTION What do you mean by a raw material by-pass? ANSWER Because No.3 kiln has a different pre-heater, part of the raw material is fed to Stage 2 direct, omitting the first stage.

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MR D CLARK, Steetly Quarry Products Ltd, United Kingdom QUESTION How do you propose to deal with fouling on the heat exchanger surface? ANSWER This is avoided by inclusion of soot-blowers and water washing. After this question and answer session, the delegates visited CIMPOR’s Souselas Plant.

THIRD SESSION—ROUND TABLE DISCUSSION Chairman: Professor Mario Nina, University of Lisbon

ROUND TABLE DISCUSSION Chairman: Professor Mario Nina, University of Lisbon Contributors: K W Bezant, Blue Circle Cement, United Kingdom F Aellen, Holderbank, Switzerland Professor G Parisakis, University of Athens, Greece J Sirchis, Commission of European Communities E Steinbiss, KHD, BR Deutschland H Takakusaki, NIHON Cement Co, Japan

1. SUMMARY OF PAPERS MR SIRCHIS opened the discussion with a summary of all the papers presented on the previous day and the two presented earlier in the second day. 2. CEMENT WORLD MARKET MR BEZANT, Blue Circle, gave an overview of the world cement market. By the year 2000 it was anticipated that per capita demand would increase to between 227 and 257 kg. Total demand in Europe would be between 1400 and 1600 million tonnes/annum assuming a population of 5.2 billion by the year 2000. European production capacity is currently 1300 million tonnes/annum, therefore current capacity falls short of the most pessimistic level of demand. To satisfy the increased demand it is considered that between 50% and 70% of the increased capacity will come from modifying existing plant. The remaining shortfall will be met by new plant. To increase output will require an investment of between US $6 and US $22 billion. Modernising plant to increase output costs around $30/tonne and new plant $120/tonne. The additional fuel to manufacture this cement will be equivalent to between 35 and 40 million tonnes/ annum of oil. MR STEINBISS of KHD, BR Deutschland commented that it will be necessary to reduce fuel consumption by 5%/annum to remain at the same current overall level of energy consumption. To reduce

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153

overall demand for energy in the cement industry will involve an annual reduction in specific energy consumption by more than 5%/annum. 3. ENVIRONMENT MR AELLEN of Holderbank commented on the environmental impact of the cement industry. The Swiss limitations were similar to those applied in West Germany which are currently: mg/m3 50 30 30 500 750

Dust emission Ammoniac Chlorhydrogen Sulphur dioxide NOx NO2

Technology exists to reduce dust levels to 15 mg/m3. Sulphur dioxide emissions can be reduced by mixing lime hydrate with the raw meal feed or introducing it after the conditioning tower. These methods have reduced SO2 emissions to less than 500 mg/m3. NOx emissions have been reduced by lowering the kiln temperature or by installing low NOx burners which have provided a 30% to 40% reduction in NOx levels. No adequate solution has been found to control the level of ammoniac emission. Waste burning can cause problems with dioxin emissions. There are currently no limits set for carbon monoxide emission, however these are to be expected to be introduced in the next few years. Because of the ‘greenhouse’ effect, it may become necessary to reduce CO2 emissions. Currently most cement in Europe is produced using coal. For each tonne of clinker produced with coal there is one tonne of CO2 discharged into the atmosphere. This emission could be halved if coal was substituted with natural gas. MR TAKAKUSAKI, NCC, Japan stated that the Japanese limits were: NOx Dust SO2

480 ppm @ 10% oxygen content 100 ppm/m3 30 ppm

To achieve these levels, primary air must be reduced to less than 7%. One kiln has been successfully operated at less than 4% primary air resulting in reduced levels of NOx. Also at the outlet from the first stage cyclone O2 has been reduced to less than 3% also resulting in reduced NOx levels. The Japanese cement industry is using the ‘Linkman’ Expert System to fine-tune the control of kilns. This type of system can be used to avoid everburning in the burning zone which results in reduced NOx emissions. Dust burdens are being reduced by the use of electrostatic precipitators. The oxygen level at the electrostatic precipitator is around 7%. Providing the whole process is under effective control, NOx levels should be at an acceptable level. CO2 emissions can be reduced by the use of branded cement. There were no examples of SO2 control provided.

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The Chairman, PROFESSOR MARIO NINA, University of Lisbon, contributed by giving the relative quantities of CO2 emissions when burning different types of primary fuel: Gas Oil Coal

= = =

1 1.32 1.52

Significant scope exists to reduce overall energy demand by 15 000 tonnes of oil equivalent by the increased use of cogeneration. This will provide reductions in CO2 emissions of 57000 tonnes/annum. 4. ENERGY PRICES MR BEZANT, Blue Circle Cement, commented that all energy prices are interrelated due to market forces, but there may be a time delay. The important factors are: i The price per kCal for each type of fuel should be monitored. ii is the energy source indigenous—what extra costs are associated with transporting the energy to its point of use? If the energy has to be imported what impact will this have on the country’s balance of payments? iii Predicting the future price of energy and current exchange rates make it difficult to determine whether an investment will be worthwhile. The cement industry is capital intensive and most plant has between a 20 and 40 year life. 5. EUROPEAN NORMS MR BEZANT, BCC, stated that Env.197 has not been accepted as presently drafted but should be introduced by 1992/93. When accepted, this will reduce the total energy content of cement and mortar by enabling more fillers to be introduced. Increasing the filler content of cement will reduce the rate at which new plant is required. The opportunity to replace inefficient plant with new plant will therefore be reduced. With a Common European Standard, investment confidence may improve, but unfortunately we have lost two years in potential to achieve further energy savings. 6. ENERGY EFFICIENCY MR STEINBISS, KHD, commented that the possibilities to make further energy reductions are limited. Forty years ago using the wet process specific consumption was 1400/1600 kCal/kg of clinker. Steady improvements have been made by introducing first the semi-wet process, then the dry process and finally calciner kilns giving reductions to 700 kCal/kg clinker. It is only poorer performing countries that have significant scope to improve efficiency. Waste heat recovery can be used to win back some of the wasted heat. This is only suitable for larger kilns with exhaust gases with low moisture contents.

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155

Reducing electrical energy consumption is a real step to reduce primary energy consumption. Optimisation of cement mills utilising high pressure communation technology—roller presses. To date, 200 machines have been sold resulting in savings of around 10 kWh/tonne. MR BEZANT added that he thought that the overall presentations at the seminar had been excellent. The projects discussed had been interesting but none represented a dramatic breakthrough. There were very few cases of revolution, only evolution. The UK cement industry has a target of reducing energy consumption by 20% to 700 kCal/kg. Such a reduction would be difficult in Japan and other countries which are already achieving these levels of consumption. Waste heat boilers are not new and were in use in the cement industry 70 years ago. Two papers touched on energy management, and the concept of total Quality Circles in Japan was mentioned. The individual human being has an important role to play in making improvements. The cement industry is not particularly glamorous and there may be a problem attracting quality staff. One challenge for the future is to ensure that we attract the necessary quality people to the industry. Following this contribution, the meeting was opened to comments and questions. QUESTION MR TAKAKUSAKI, NCC, Japan, asked what the operational level was in the European cement industry. ANSWER MR BEZANT, BCC, advised that in the UK (Blue Circle Cement) the target is 90% which is not always achieved. Planned maintenance in January/February shutdowns accounted for 5% output and none planned between 3% and 5% is fairly typical QUESTION MR PALIARD, CLE, France, Question to MR STEINBISS regarding the roller press. Do you think that the roller press of the classification system is the reason for the shape of the curve? ANSWER The size distribution is closer than that from a ball mill. The cement produced from a roller mill tends to have a higher water demand. MR GONCALES, Centre Estudos Economia Energia, Portugal COMMENT

There has been a lot of discussion about energy recovery but mostly we have heard that this is used either for heating or for electrical energy production. There has been no mention of heat recovery for cooling and there is an example of this in Portugal, which may not have any precedent. CIMPOR has a system for heating and cooling using waste heat from the clinker cooler. This is on a kiln with an output of 1350 tonnes/day. They recycle around 50% of the exhaust fumes at a temperature of 180–200°C (around 50000 m3) in order to recover heat using a boiler with a capacity of 1.2 MW. This heat is used for heating a large sack factory with an area of around 12000 m2. In addition, the heat is used to heat technical and administrative offices in winter. Cooling is provided in summer from a chiller plant set up using the Lithium method with a power capacity of around 0.8 MW. Savings equivalent to around 30 million escudos/annum of electrical power are achieved. Heating accounts for savings of 20 million escudos and cooling accounts for 10 million escudos. The payback period is less than two years. QUESTION

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

TOM LOWES, BCC, to Holderbank and MR STEINBISS regarding the installation of KHD burners where it was stated that reductions of up to 40% in oxides of nitrogen were achieved. Could you tell us the level you were at to begin with and what you went down to? Did you have any significant increase in fuel consumption, instability in the kiln or SO2 emission? In Blue Circle we have found that we can reduce oxides of nitrogen by eliminating reducing conditions in the kiln. ANSWER This burner has been developed to work on low primary air quantities of between 6% and 8%. The primary air is introduced through a single jet nozzle. The NOx reduction is a by-product of the introduction of the burner which is caused by lower temperatures of parts of the flame. In addition, there is a reducing effect. Fuel consumption is unchanged but NOx levels have been lowered. KHD will guarantee a reduction of 20% NOx emissions. MR AELLEN, Holderbank, added there was a reduction of between 500 and 1000 mg/m3 of NOx emissions in kilns with planetary coolers. In kilns with grate coolers, reductions were between 1000 and 1800 mg/m3.

CLOSING SESSION Chairman: V Teixeira Lopo, President of CIMPOR

CONCLUSIONS by MR D QUIRKE, a representative of CEMBUREAU CEC, Ministry of Industry

1. The contributions to the Seminar show that the cement industry has given considerable attention to improving energy efficiency in clinker manufacture. The overall effect of the transfer from wet to dry process has been to reduce fuel usage by approximately 35 %. 2. The European Cement Industry has been and continues to be the largest user of secondary materials in cement for ordinary concretes compared with the industry in other major world areas. The energy saving is almost in direct proportion to the amount of secondary material added. 3. It has also adopted, particularly since the second oil crisis in the late 70’s, a highly flexible approach in the selection of energy supplies. For high grade funds, it has responded quickly to market trends and most plants can handle a variety of fuels, or mixtures of them. It has become the principal consumer of petcoke. This is an important contribution to EC Energy Policy as it reduces dependence on individual sources. 4. The industry therefore welcomes all EC actions directed to keeping available every possible energy source. 5. Contrary to the situation for kiln fuel, the cement industry has no choice as regards electricity, the cost of which in some plants is as high, and can even exceed that for the kiln fuel. The industry equally supports therefore EC efforts towards the liberalisation of the electricity market, giving access to the grids by outside parties, and the possibility for industry to negotiate with different suppliers. 6. The environmental consequences of the cement industry’s use of waste and low grade fuels, which would otherwise be dumped, should be recognised. The EC principle that the polluter pays is an acceptable one. However, it is necessary to be clear about the transfer of responsibility. The industry which eliminates this environmental problem should not be equated with, or treated in the same way as the industries which produce the waste products.

CONCLUSIONS

159

Any regulations or legal measures which discourage the cement industry from performing this service will create new environmental problems.

ABREU C. SEC.ESTADO ENERGIA Rua Horta Seca 15 1200 LISBOA PORTUGAL ABREU Mario LNETI Azinhaga Dos Lameiros Estrada Do Paco Do Luminar 1600 LISBOA PORTUGAL AHLKVIST BO CEMENTA AB PO Box 102 S-620 30 SLITE SWEDEN ANINGO C.C. BENUE CEMENT COMPANY LTD P.M.B. 12702 LAGOS NIGERIA BAGUENIER H. CENTRO ESTUDOS ECON.ENERGIA Rua Miguel Lupi, 20 1200 LISBAO PORTUGAL BARALIS R. ITALCEMENTI Via G.Camozzi, 124 24100 BERGAMO ITALY BARREIRQ Antonio Cald SECIL Outão 2900 SETUBAL PORTUGAL ABREU Carlos M.

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Rua Miguel Lupi, 20 1200 LISBAO PORTUGAL BARALIS R. ITALCEMENTI Via G.Camozzi, 124 24100 BERGAMO ITALY BARREIRQ Antonio Caldas SECIL Outão 2900 SETUBAL PORTUGAL ABREU Carlos M. SECIL Outao 2900 SETUBAL PORTUGAL AELLEN F. HOLDERBANK PO BOX 8750 GLAIRS SWITZERLAND ANDRADE S. CIMPOR Centro de Prod. de Souseias 3000 COIMBRA PORTUGAL AZIZZ Hamouda A. ALEXANDRIA PORTLAND CEMENT CO P.O.S. El Mex ALEXANDRIA EGYPT BAILLY M. CIMENTS DE CHAMPAGNOLE 21, rue Clauzei 75009 PARIS FRANCE BARRACHA FR. DIRECAO-GERAL QUALIDADE AMBIENTE Rua do Século, 51 1200 LISBOA PORTUGAL BENITO Frederico Adrian HORNOS IBERICOS ALBA S.A.

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Nunez de Balboa, 35-A 28001 MADRID SPAIN BERTRAND ASLAND Orense, 81 28020 MADRID SPAIN BEZANT K.W. BLUE CIRCLE 305 London Road Greenhithe KENT DA9 9JQ U.K. BLANCK M. HOLDERBANK MAN.&CONSULTING LTD 5113 HOLDERBANK SWITZERLAND BORGES H.A. SOCIEDADE CIMENTO NAC.DE MINAS S.A. Apart.11-Torre da Marinha 2842 SEIXAL CODEX PORTUGAL BREUER ALLMINERAL AUFBEREITUNGS TECH. Gmbh Vulkanstrasse, 36 4100 DUISBURG 1 GERMANY BUHLMANN ASEA BROWN BOVERI LTD 5401 BADEN SUISSE CAMPOS E. CIMPOR Rua Alexandre Hercuiano 35 1200 LISBOA PORTUGAL BESSAD Hamed ENFIDA CEMENT INDUSTRIE BN7–4030 ENFIDHA TUNISIA BIRCH E. F.L.SMITH 77, Vigersiev Alle 2500 VALBY COPENHAGEN DENMARK

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

BOLLER Nikolaus CIMINAS-Cimento Nac.de Minas S.A. Vargem Alegre-Calxa Postal 20 33.600 Pedro Leopoido-M.G. BRASIL BOUQUELLE J.F. CIMENTS D’OBOURGS Rue des Fabriques, 2 7048 MONS OBOURG BELGIUM BROCKHAUSEN UDO SCHULZE CHRISTIAN PFEIFFER Gmbh Sudhoferweg 110/112 4720 BECKUM GERMANY BURGUERA J. CORPORATION NOROESTE San Salvador, 2–4° 36204 VIGO SPAIN CANDEIAS Manuel J.Sengo PRECISAL Largo Conde Barao, 34–2° Esq° 1200 LISBOA PORTUGAL CARDOSA e CUNHA CCE 200 rue de la Lol 1040 BRUXELLES BELGIUM CARVALHO C. CIMPOR Centro de Prucao de Souselas 3000 COIMBRA PORTUGAL CASTELA A. CIMPOR Centro de Producao de Maceira 2400 LEIRIA PORTUGAL CHEAH ALLEN H.M. WISMA APMC, 2 Jalan Kilang 46050 PETALING JAYA SELANGOR

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MALAYSIA CLARCK D.P. STEELEY QUARRY PRODUCTS LTD Middleton St George DARLINGTON CO DURHAM DL2 1HR U.K. COELHO C. LNETI Praça do Principe Real, 19 1200 LISBOA PORTUGAL COLLOMB B. LAFARGE COOPPEE 28, rue Emile Meunier 75782 PARIS CEDEX 16 FRANCE CARRER CIMENTS DU KAMEROUN B.P. 1323 DOUALA KAMEROUN CASSOU D. SOCIETE DES CIMENTS FRANCAIS Les Technodes 78931 GUERVILLE Cedex FRANCE CATALAO J. EURANTIC Apartado 17 2766 ESTORIL CODEX PORTUGAL CIFUENTES POLYSIUS S.A. PI.Manuel Gomez Moreno s/n Ed.Bronce 28020 MADRID SPAIN COCHET Francis 5, bd.Louis Nucher 92211 St CLOUD FRANCE COLLIS CEMBUREAU 55 rue d’Arion

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

1040 BRUXELLES BELGIUM CONSO P. CIMENTS FRANCAIS Tour Générale-Cedex 22 92088 PARIS LA DEFENSE FRANCE CORREA Virginia DIRECCAO GERAL DE ENERGIA Rua Da Beneficencia 241 1600 LISBOA PORTUGAL DAMATO Michel POLYSIUS S.A. 30, Bd.Beilerive-BP 243 92504 RUEIL MALMAISON Cedx FRANCE DEKKICHE A.B.B. Department ITE 5401 BADEN SWITZERLAND DIVINO COMP.DE CIMENTO PORTLAND PARAISO Av. Rio Branco, 103/18° Centro CEP 20040 RIO DE JANEIRO BRASIL DUMAS J. CIMENTS FRANCAIS Les technodes 78931 GUERVILLE CEDEX FRANCE EL DALLY AHMED F. SUEZ CEMENT CO 35 Ramses street Nile Bank Building CAIRO EGYPT EL MIKENY AHMED alexandria Portland cement P.O.B. El Mex ALEXANDRIA EGYPT COUTINHO F. CIMPOR Centre de Producao de Patalas

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2430 MARINHA GRANDE PORTUGAL DE TERVARENT P.DE SCHOUTHEETE 62, rue Belliard 1040 BRUXELLES BELGIUM DENTON John T. CASTLE CEMENT LTD Clitheroe LANCASHIRE BB7 4QF U.K. DUFRESNOY Frederique GEC Alsthom 141, rue Rateau 93123 LA COURNEUVE FRANCE DURAO D. INTERG I.S.T. Av. Rovisco Pais 1096 LISBOA PORTUGAL El Gabry Nabil HELWAN PORTLAND CEMENT CO P.O.Box 16 HELWAN EGYPT EL NADY FEKRY ABD SUEZ CEMENT CO 35 Rambes street Nile Bank Building CAIRO EGYPT EL TOUNNY NATIONAL CEMENT CO 5–26 July street PO Box 18 CAIRO EGYPT ESOKAMBA SOCIETE DES CIMENTS DU GABON B.P. 477 LIBREVILLE GABON FERRANDO J. COMP.VALENCIANA DE CEM.PORTLAND

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Colon, 68 46004 VALENCIA SPAIN FLAMENT G. SOCIETE DES CIMENTS FRANCAIS Les Technodes 78931 GUERVILLE Cedx FRANCE FRADERA Enrique UNILAND CEMENTERA S.A. Corceqa, 299 08008BARCELONA SPAIN FUJIRAWA T. TAKUMA CO LTD 3–23 Dojima Hama I-Chome KITA KU OSAKA 530 JAPAN FURTADO F. ASEA BROWN BOVERI Av. Cons.Fernando Sousa 25 1000 LISBOA PORTUGAL ELWAY MAHMOUD NATIONAL CEMENT CO 5–26 July street P.O.Box 18 CAIRO EGYPT ETOC ASS.TEC.IND.LIANTS HYDRAULIQUES 8, rue Villiot 75012 PARIS FRANCE FERREIRA José Bravo SECIL Outão 2900 SETUBAL PORTUGAL FLAUX Jean Pierre GEC Alsthom 141, rue Rateau 93123 LA COURNEUVE FRANCE FRITZ

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

CIMENTS DU TOGO 11687 LOME TOGO FUKUSHIMA H. NCC OHTEMACHI BLDG 6–1 1-Chone Ohtemachi Chiyo TOKYO JAPAN FYNES Geoffrey BRITISH COAL CORPORATION Stoke Orchard CHELTENHAM GL52 4RZ GREAT BRITAN GERMER A. NORICUM Postfach 3 8940 LIEZEN AUSTRIA GOMES A.SOARES CIMPOR Rua Alexandre Hercuiano 35 1200 LISBOA PORTUGAL GRIBAT ALLMINERAL GMBH CO.KG Vulkanstrasse 36 4100 DUISBURG 1 GERMANY GUPTA R.K. J.K. CEMENT WORKS Kamla Tower KANPUR INDIA HAN BANG YUN MANIL CEMENT MFG.CO 832–2 Yuksam Dong Kangnam Ku SEOUL KOREA HARGREAVES D. INTERNATIONAL CEMENT REVIEUW 320 High street, Dorking SURREY RH4 1QY U.K. HASPEL D.W.

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Kelvin House Worsley Bridge Road Sydenham LONDON SE26 5BX U.K. GOCER C. ADANO CIMENTO SANAYII T.S.A. Ceyhan Yolu Uzeri 12km ADANA TURKEY GOUVEA Bernardo Mandonca ALSTHOM INTERNATIONAL Apartado 1362 1011 LISBOA Codex PORTUGAL GROZELLIER J.P. CIMENTS DE CHAMPAGNOLE BP 339 30104 DOLE CEDEX FRANCE HAILER POLYSIUS S.A. PI.Manuel Gomez Moreno s/n ED.Bronce 28020 MADRID SPAIN HANDOYO JUFRI WISMA INDUCEMENT Level 13/PO Box 4018 JL.Jend Surdinam Kau 70–71 JAKARTA 12910 INDONESIA HARTOWO SEMEN ANDALAS INDONESIA A1ced Office Lho Nga Km 16 BANDA ACEH INDONESIA HASSEN K. HELWAN PORTLAND CEMENT CO PO Box 16 HELWAN EGYPT HAWKINS J. ARAWAK CEMENT COMPANY LTD Checker Hall St Lucy

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

BARBADOS CENTRAL AMERICA HIGASHIMURA EURANTIC Apartado 77 2766 ESTORIL PORTUGAL HOMASSEL Bernard LAFARGE COPPEE 28, rue E.Meunier 75782 PARIS FRANCE HUNZIKER PAUL INDUSTRIA NACIONAL DE CEMENTO S.A, Apdo.4009–1000 SAN JOSE COSTA RICA CENTRAL AMERICA JARRETT PAT Checker Hall St Lucy BARBADOS CENTRAL AMERICA JIRI PTACEK CEE Kwerpsebaan 153 3071 KORTENBERG BELGIQUE KARRASH Gerd HORNOS IBERICOS ALBA S.A Nunez de Balboa, 35_A 28001 MADRID SPAIN HENSGEN H. O & K ORENSTEIN KOPPEL Bresiauer Strasse 27 4722 ENNIGERLOK GERMANY HO YEON LEE HYUNDAI CEMENT CO An 2–1 Jamwon Dong Seo Cho Ku SEOUL KOREA HOUBER

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

BAMBOURI PORTLAND CEMENT P.O.Box 90202 MOMBASSA KENYA IN YOUNG LEE SSANGYONG CEMENT INDUSTRIAL CO Ssangyong Blgd.24–1 2-GA Jeo Dung Junk GU SEOUL 100–748 KOREA JHALORI K.K. BRITISH COAL CORPORATION Kamla Tower KANPUR INDIA JONGEN J.H. ENCI NV Postbox 1 6200 AA MAASTRICHT NETHERLANDS KAUFFMANN Jean Paul POLYSIUS S.A. 30, Bd Belierive-BP 243 92504 RUEIL MALMAISON Cedex FRANCE KESMEZ H. ADANO CIMENTO SANAYII T.S.A. Ceyhan Yolu Uzeri 12 Km ADANA TURKEY KIM KWANG SOO 832–2, Yuksam Dog Kangnam Ku SEOUL KOREA KINDERMANN F. CCE 200 rue de la Loi 1049 BELGIUM KLINCKHAMERSL CEMENTFABRIEK ROZENBURG ROBUR P.O. Box 1030–3180 AA ROZENBURG ZH NETHERLANDS

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

KONIG HERRN ABTEILUNG FORSCHUNG + ENTWICKLUNG 3320 SALZGITTER 41 GERMANY LASUDSAKU Oidijai JALAPRATHAN CEMENT CO 2974 NEW PETCHBURI ROAD BANGKOK 10310 THAILAND LEITAO F. CIMPOR Rua Alexandre Hercuiano 35 1200 LISBOA PORTUGAL KHOR ASSOCIATED PAN MALAYSIA CEMENT SDN Rawang Works 48000 RAWANG SELANGOR MALAYSIA KIM SEUNG BAE SSANGYONG HEAVY INDUSTRIES CO Dong Hae Plant/200, Samwha Dong Kwanngwon Do 240 350 SEOUL KOREA KIRDRATANASAK SANYA JALAPRATHAN CEMENT CO Takli Factory 1 Jalaprathan Cement Road Takil NAKORNSAWAN 60140 THAILAND KNUDSEN Per GOTLANDS ENERGIVERK AB P.O.Box 17 620 30 SLITE SWEDEN LABO KADA ABOUCADAR MIN.DE INIETTEL DES SOCIETES BP 12375 NIAMEY NIGER LAWTON J. CEMBUREAU 55 rue d’Arion

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

1040 BRUXELLES BELGIUM LEONG G.C. KADAH CEMENT SDN. BHD. 31st fl.Menara Da to Onn 50480 KUALA LUMPUR LIBERT J. CARRIERES ET FOURS A CHAUX Av. Rogier 21 4000 LIEGE BELGIUM LINK GUNTER LA CEMENTO NACIONAL CEM. P.O. Box 4243 Guayaquil ECUADOR SOUTH AMERICA LOPEZ ALVARO SISA CEMENTOS DIAMANTE S.A. Fabrica del Norte Ap.A.1166 CUCUTA COLOMBIA LOWES T.M. BLUE CIRCLE 305 London Road Greenhithe KENT DA9 9JQ U.K. MAINE EAST AFRICAN PORTLAND CEMENT P.O. Box 40101 NAIROBI KENYA MARTIN D. STURTEVANT MILL CO EUROPE 8–10, av. de Saturne 1180 BRUXELLES BELGIUM MAYNARD JEAN PIERRE GAZ DE FRANCE D.E.C. 23, rue P.Deiorme 75017 PARIS FRANCE

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

LIBERT JOSEPH CARRIERES ET FOURS A CHAUX Av.Rogier 21 4000 LIEGE BELGIQUE LIVONEN ARTO LOHJA CORPORATION CEMENT FACTORY 08700 VIRKKALA FINLAND FINLAND LOPO T. CIMPOR Rua Alexandre Hercuiano 35 1200 LISBOA PORTUGAL MAHER BADR NATIONAL CEMENT CO 5–26 Juky street P.O. Box 18 CAIRO EGYPT MAKRIS M. CLE Cedex 23 92290 PARIS LA DEFENSE FRANCE MATEOS Manuel Paz HORNOS IBERICOS ALBA S.A. Nunez de Balboa, 35-A 28001 MADRID SPAIN MENDES E.L. EFACEC Rua Rodrigo de Fonseca 76–3° LISBOA PORTUGAL MENDES M. D.G. DE ENERGIA Av. de la Republica, 45–5° 1000 LISBOA PORTUGAL METWALLY MOHAMED HELWAN PORTLAND CEMENT CO PO Box 16 HELWAN EGYPT

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

MICHINO T. KAWASAKI HEAVY INDUSTRIES LTD Oststrasse 10 4000 DUSSELDORF 1 GERMANY MIELL Pat S. CASTLE CEMENT LTD Ketton, NR Stamford LINCS PE9 3SX U.K. MIN UNG CHEE SSANGYONG CEMENT INDUSTRIAL CO C.P.O. BOX 4106 SEOUL KOREA MOMMENS Henri CBR CIMENTERIES S.A. Ch. de la Hulpe, 185 1170 BRUXELLES BELGIQUE MOSTEFA DELLA Ahmed CIMENTERIE D’ECH CHELIFF BP 54 ECH CHELIFF ALGERIE MERLE S.C.A. SOC.DES CIMENTS D’ABIDJAN B.P. 3751 Bd.Portuaire ABIDJAN COTE D’IVOIRE MEZAR MAGED SUEZ CEMENT CO 35 Ramses Street Nile Bank Building CAIRO EGYPT MIEBACH Sohne PORTLANDZEMENTWERK WITTEKIND HUUGO Postfach 1106 4782 ERWITTE GERMANY MIGUENS C. DIRECCAO GERAL DA ENERGIA Rua da Beneficiencia, 241

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

1600 LISBOA PORTUGAL MOINE J. CLE Cedex 23 92290 PARIS LA DEFENSE FRANCE MOSES I.AENDE BENUE CEMENT COMPANY LTD P.M.B. 12702 LAGOS NIGERIA MUELLER J. JCF-JURA CEMENT FABRIKEN Aarau Wildegg 5103 WILDEGG SWITZERLAND MURTRA Isidoro LA AUXILIAR DE LA CONSTRUCCION S.A. Av. Diagonal 534 08006 BARCELONA SPAIN NALACACI H. ADANA CIMENTO SANAYII T.S.A. Ceyhan Yolu Uzeri 12Km ADANA TURKEY NETO S. CIMPOR Centro de Producao de Alhandra 2600 VILA FRANCA DE XIRA PORTUGAL NIELSEN Knud Frils F.L.Smidth & Co. A/S Vigersiev Allé 77 2500 Valby DENMARK NISSEN Torben F.L.Smidth & Co. A/S Vigersiev Allé 77 2500 Valby DENMARK NYAGBA I.Solomon BENUE CEMENT COMPANY LTD P.M.B. 12702

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

LAGOS NIGERIA OGAWA EURANTIC Apartado 77 2766 ESTORIL CODEX PORTUGAL NAGEH GAMAL HELWAN PORTLAND CEMENT CO PO Box 16 HELWAN EGYPT NETO J.M. CIMPOR Centro de Producao de Souselas 3000 COIMBRA PORTUGAL NICOU P. 49/51 S.Venizelou st. 14123 LYCOVRISSI ATHENS GREECE NINA Mario INST.SUP.TECH. DEPT.ENGEN.MECANICA Av.Rovisco Pais 1000 LISBOA PORTUGAL NOHLMANS T. NOVEM B.V.P. Box 17 6130 AA SITTARD NETHERLANDS O KYU KWON TONG YANG CEMENT CORP. 114 Sajik Dong Samcheok City KANGWON DO KOREA OLIVEIRA M. CIMPOR Rua Alexandre Hercuiano 35 1200 LISBOA PORTUGAL OLLER OSVALDO CEMENTOS NACIONALES S.A. Apartado 14 Caretera Neila Km 10

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

SAN PEDRO DE MACORIS DOMINICAN REPUBLIC OSMAN Job SOCOCIM Cimenterie du Rufisque B.P. 39 Rufisque SENEGAL PALAHI Juan Luis Abelian TAKUMA Co.Ltd. 3–23 Dojima Hama l-Chome KITA-KU OSAKA 530 JAPAN PALOMAR P. CEMENTO HORMIGON Calie Maignon 26 08024 BARCELONA SPAIN PARISSI FRANCESCO IMPIANTI CEMENTIR S.P.A. Via Le Gorizia, 24/D 00198 ROMA ITALY PECH MICHEL VICAT TOUR GAN Cedea 13 92082 PARIS LA DEFENSE FRANCE PERALES MARIO CEMENTOS CARIBE C.A. Puerto Cumarebo Estado Falcan Apartado 7416 VENEZUELA ORTOLANI V. ITALCEMENTI Via G.Camozzi, 124 24100 BERGAMO ITALY PAIS S. ELECTRICIDADE DE PORTUGAL E.P. EDP Av. José Malhoa, lote A-13 1000 LISBOA PORTUGAL PALIARD M. CLE TOUR TECHNIP

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

170, place Henri Regnault CEDEX 23 922090 PARIS LA DEFENSE FRANCE PARISAKIS G. UNIVERSITY OF ATHENS 28 October st. 42 ATHENAS GREECE PARKES P.P. CASTLE CEMENT Clitheroe Lanes BB7 4QF U.K. PENA Angel Longareia CEMENTOS COSMOS S.A. Luchana, 23, 4° 28010 MADRID SPAIN PEREIRA A. D.G. INDUSTRIA Av. Cons.Fernando Sousa, 11 1000 LISBOA PORTUGAL PEREIRA M.C. CENTRO PARA A CONSERVACAO ENERGIA Rua S.Domingos à Lapa 117–2° 1200 LISBOA PORTUGAL PETRES Rogerio CIMENTO CAUE S.A. Rod.MG 424, km 18-P.Leopoido Caixa Postal 40 CEP: 33.600 BRASIL PIMENTEL M. CEEETA INST.SUP.ECONOMIA Rua Miguel Lupi 20 1200 LISBOA PORTUGAL PITA G. INST.SUP.TECNICO Av. Rovisco Pais 1096 LISBOA PORTUGAL PLAZA F. CIMPOR

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Centro de Producao de Alhandra 2600 VILA FRANCA DE XIRA PORTUGAL POPEK J.C. FIVES CAIL BABCOCK LILLE FRANCE RAMZY HOUSE IN SUEZ CEMENT CO 35 Ramses street Nile Bank Building CAIRO EGYPT PESENTI G. ITALCEMENTI Via G.Camozzi, 124 24100 BERGAMO ITALY PILCHMAIER NORICUM MASCHINENBAU UND HANDEL Postfach 3 4010 LINZ AUSTRIA PINHO J.S. SOFOMIL Calçada Paima de Baixo 10-B 1507 LISBOA CODEX PORTUGAL PLATSCHORRE M.I. ENCI St Teunislaan, 1 5231 BS S-HERTOGENBOSCH NETHERLANDS PONA A.P. ASEA BROWN BOVERI Av.Cons.Fernando Sousa 25-B 1000 LISBOA PORTUGAL QUIRKE D. CEMBUREAU 55 rue d’Arlon 1040 BRUXELLES BELGIUM REVILLE D. CEMBUREAU

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

55 rue d’Arlon 1040 BRUXELLES BELGIUM RICHTER G. Christian Pfeiffer Postfach 1763 Sudhofferweg 110/112 4720 BECKUM GERMANY ROBERTO Maria da Piedade Rua da Beneficencia, 241 1600 LISBOA PORTUGAL RODRIGUEZ Jesus Martinez CEMENTOS COSMOS 27392—OURAL (LUGO) SPAIN ROSARIO M. CIMPOR Rua Alexandre Hercuiano 35 1200 LISBOA PORTUGAL RUANGWIT J. JALAPRATHAN CEMENT CO 1 Jalaprathan Cement Roaéd TAKLI NAKORNSAWAN 60140 THAILAND RYU S.C. SSANGYONG 2-GA Jeo-Dong Jung-Gu SEOUL 100–748 KOREA SAMOUILHAN E. CLE Cedex 23 92290 PARIS LA DEFENSE FRANCE RITO H. CIMPOR Rua Alexandre Herculano 35 1200 LISBOA PORTUGAL RODRIGUES HELDER AVo Fernao de Magalhaes 34

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

20 Andar Maputo MOZAMBIQUE ROMAO R. CIMPOR Rua Alexandre Herculano 35 1200 LISBOA PORTUGAL ROTHER W. KRUPP POLYSIUS AG P.O. BOX 2340 4720 BECKUM GERMANY RUSHDY AHMED ALEXANDRIA PORTLAND CEMENT CO P.OB. El Mex ALEXANDRIA EGYPT SALEM DIR. NATIONAL CEMENT CO 5–26 July street P.O. Box 18 CAIRO EGYPT SANG Hyuck 24–1 2 Ka Jedo Dong Choong-Ku SEOUL PO BOX 4106 KOREA SANTOS F. CIMPOR Centro Producao Cabo Mondego 2080 FIGUEIRA DA FOZ PORTUGAL SANTOS M. CIMPOR Centre Producao Cabo Montego 3080 FIGUEIRA DA FOZ PORTUGAL SAULI Raffaeie S. C.A.C.C.I. S.P.A. Via G.B. De Rossi, 22 00161 ROMA ITALY SCHEUER A. VDZ

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Tannenstrasse 2 4000 DUSSELDORF 30 GERMANY SCHNEBERGE CIMENTS DU ZAIRE 30, Bd du 30 Juin-Building CCI B.P.7598 KINSCHASA ZAIRE SEQUEIRA A. COMETNA Rua Academia das Ciencas 5 1200 LISBOA PORTUGAL SEVEL SOCIETE DES CIMENTS FRANCAIS Les technodes 78931 GUERVILLE CEDEX FRANCE SANTOS G. SECRETARIA DE ESTADO DE ENERGIA Rua Horta Seca 15 1200 LISBOA PORTUGAL SARAIVA J. CIMPOR Rua Alexandre Hercuiano 35 1200 LISBOA PORTUGAL SCANTLEBURY ANTHONY ARAWAK CEMENT COMPANY Checher Hall St Lucy BARBADOS CENTRAL AMERICA SCHMIDT MANFRED O&K anlagen systeme g.a 4722 ENNIGERLOH GERMANY SEONG SOO KIM SSANGYONG/CEMENT IND.CO Ssangyong Bld., 24–1 2GA Jeo Dong Jung-Gu SEOUL 100–748 KOREA

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

SEQUEIRA J. AUDITERG Rua Edison 3-r/c-E 1000 LISBOA PORTUGAL SHALABY Sai HELWAN PORTLAND CEMENT CO P.O. BOX 16 HELWAN EGYPT SHIM YONG JIN HANIL CEMENT MFG.CO 832–2 Youksamdong Kangnam Ku SEOUL KOREA SHUTLER Michael V. ASEA BROWN BOVERI LTD Hasseistrasse 5401 BADEN SUISSE SILVA R. SECRETARIO DE ESTADO DA ENERGIA Rua da Horta Seca 15 1200 LISBOA PORTUGAL SING LEE CHOON 17, Pioneer Crescent, Jurong Town SINGAPORE 2262 SINGAPORE SOARES Jarbas Fernandes CIMENTO CAUE S.A. Rod.MG 424, km 18-P.Leopoido Calxa Postal 40 CEP.: 33.600 BRASIL SORNIN B. CLE Cedex 23 92290 PARIS LA DEFENSE FRANCE SOUSA J. CIMPOR Centro Producao de Souseias 3000 COIMBRA PORTUGAL

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

SHIRANE M. TAKUMA CO.LTD Eitaro Block-2–5 Nihon Bashi 1 CHOME CHUO KU TOKYO JAPAN SIMAO V. LNETI Rua S.Pedro de Alcantara 79 1200 LISBOA PORTUGAL SILVA O. CIMPOR Centre Producao de Louie 8101 LOULE CODEX PORTUGAL SIRCHIS J. CCE 200 rue de la Lo 1049 BRUXELLES BELGIUM SODERSTROM Sten Box 17 62030 SLITE SWEDEN SOUSA H. LNETI Az.Lameiros Estrada Paço Lumi 1600 LISBOA PORTUGAL STEINBISS E. KHD Postfach 910404 5000 KOLN 91 GERMANY SYAIFUL IR. PT.SEMEN PADANG PO BOX 94 PADANG 25237 INDONESIA TAKAKUSAKI H. NCC OHTEMACHI BLDG 6–1 1-Chone Ohtemachi Chiyo TOKYO JAPAN TAVERAS ANDRES SANTOS

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

CEMENTOS CIBAO,C FOR A Apartado Palo Amarillo SANTIAGO DOMINICAN REPUBLIC TOMAZ I. CIMPOR Rua Alexandre Herculano 35 1200 LISBOA PORTUGAL TORRES A. ASLAND Orense 81 28029 MADRID SPAIN VALLE J.G. ASLAND Orense 81 28020 MADRID SPAIN VERGARA ROLANDO ARIZA COMPANIA COLOMBANIA DE CLINCER S.A Apartado Aereo 3344 CARTAGANA COLOMBIA SOUTH AMERICA TAE KYUN LEE ASIA CEMENT MFG CO 120–23 Seosomoon-Dong Chung-Ku SEOUL KOREA TANGNEY Sean IRISH CEMENT LTD Stillorgan Road STILLORGAN.CO.DUBLIN IRELAND TELFORD R. IRDAC 200 rue de la Loi 1049 BRUXELLES BELGIUM TORRE Manuel Aizpuru CEMENTOS LEMONA S.A. Alda.de Urquijo, n°10–2° 48008 BILBAO (BIZKAIA)

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

SPAIN TRAKIDIS TITAN CEMENT COMPANY S.A. 8, Dragatsaniou street 10559 ATHENS GREECE VASCONCELOS I. DIRECCAO GERAL QUALIDADE AMBIENTE PORTO PORTUGAL VIAUD MICHEL PERALTA CEMENTO DE EL SALVADOR S.A. P.O. Box (05) 17 SAN SALVADOR EL SALVADOR CENTRAL AMERICA VILLAR J.R.M. FABRICIA DOMINICANA DE CEMENTO Apartado Postal 1335 SANTO DOMONGO DOMINICAN REPUBLIC WEINERT K.H. INTERATOM Postfach, Friedrich Fbert strasse 5060 BERGISH GLADBACH 1 GERMANY WERNER B. ASEA BROWN BOVERI LTD Hasseistrasse 5401 BADEN SUISSE ZIEGENFUSS Jochen WIETERSDORFER & PEGGAUER Wietersdorf 9373 KLEIN ST PAUL AUSTRIA VIRTUTO JR. FR. HI CEMENT CORPORATION Kal.Buil.164 Salcedo street LEGASPI VILLAGE, MAKATI PHILIPPINES WEIT H. Christian Pfeiffer Postfach 1763 Sudhofferweg 11/112

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ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

4720 BECKUM GERMANY YUS FF OMAR trinidad cement ltd Southern Main Road Claxton Bay IRINIDAD SOUTH AMERICA ZOUBOV N. STURTEVANT MILL Co EUROPE 8–10, av.de Saturne 1180 BRUXELLES BELGIQUE

INDEX OF AUTHORS

AELLEN, F, 155 AHLKVIST, B, 73

PARKES, P F, 88 QUIRKE, D, 161

BAILLY, M, 129 BEZANT, K W, 137, 155 BIRCH, E, 118 BLANCK, M, 96 BOUQUELLE, J-F, 78

RIBEIRO DA SILVA, N, 8 SCHEUER, A, 27 SIRCHIS, J, 155 SOARES GOMES, A., 23 SPRUNG, S, 27 STEINBISS, E, 57, 155

DUMAS, J, 109 GARCIA DEL VALLE, J, 36 KINDERMANN, F, 3

TAKAKUSAKI, H, 155 TORRES, A, 36

LOWES, T M, 137

WEINERT, K-H, 82

MAKRIS, M, 129 MENARDI, G, 129 NAKAJIMA, Y, 48 NETO, M, 145 PALIARD, M, 129 PARISAKIS, G, 155 189