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Page 1: Ebooksclub.org Energy Efficiency in the Cement Industry
Page 2: Ebooksclub.org Energy Efficiency in the Cement Industry

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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Proceedings of a seminar organised by the Commission of the European Communities, Directorate-Generalfor Energy and CIMPOR Cimentos de Portugal E.P. with the co-operation of Cembureau European CementAssociation, 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 editorialassistance.

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ENERGY EFFICIENCY IN THECEMENT INDUSTRY

Edited by

J.SIRCHISDirectorate-General for Energy,

Commission of the European Communities,Brussels, Belgium

ELSEVIER APPLIED SCIENCELONDON and NEW YORK

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ELSEVIER SCIENCE PUBLISHERS LTDCrown House, Linton Road, Barking, Essex IG11 8JU, EnglandThis edition published in the Taylor & Francis e-Library, 2005.

“To purchase your own copy of this or any of Taylor & Francis or Routledge’s collectionof thousands of eBooks please go to www.eBookstore.tandf.co.uk.”

Sole Distributor in the USA and CanadaELSEVIER SCIENCE PUBLISHING CO., INC.

655 Avenue of the Americas, New York, NY 10010, USAWITH 26 TABLES AND 55 ILLUSTRATIONS

© 1990 ECSC, EEC, EAEC, BRUSSELS AND LUXEMBOURGBritish Library Cataloguing in Publication Data

Energy efficiency in the cement industry.1. European Community countries. Industries. Energy.

ConservationI.Sirchis, J.

658.26

ISBN 0-203-21565-6 Master e-book ISBN

ISBN 0-203-27196-3 (Adobe eReader Format)ISBN 1-85166-546-3 (Print Edition)

Library of Congress CIP data applied forPublication arrangements by Commission of the European Communities, Directorate-General

Telecommunications, Information Industries and Innovation, Scientific and Technical CommunicationUnit, Luxembourg

EUR 12756LEGAL NOTICE

Neither the Commission of the European Communities nor any person acting on behalf of theCommission is responsible for the use which might be made of the following information.

No responsibility is assumed by the Publisher for any injury and/or damage to persons or property asa matter of products liability, negligence or otherwise, or from any use or operation of any methods,

products, instructions or ideas contained in the material herein.Special regulations for readers in the USA

This publication has been registered with the Copyright Clearance Center Inc. (CCC), Salem,Massachusetts. Information can be obtained from the CCC about conditions under which photocopies of

parts of this publication may be made in the USA. All other copyright questions, includingphotocopying outside the USA, should be referred to the publisher.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted in any form or by any means, electronic, mechanical, photocopying, recording, or

otherwise, without the prior written permission of the publisher.

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PREFACE

The existence of significant uncertainty as to the long-term prospects for energy supply and demandfollowing the rapid fall in oil prices, has stimulated both the international energy situation as well as that ofthe Community and made it essential that the substantial progress already made in restructuring theCommunity’s energy economy be maintained and, if necessary, reinforced.

The European Energy Policy objectives for the year 1995 call for adequate energy supply, controlledenergy prices and increased environmental concern. All of these constraints necessitate the rationalexploitation 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 finallythrough the development of new technologies to augment both saving and efficiency. Better insulation, heatand 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 cementindustry in EEC countries, some stages of cement production still offer opportunities for furtherimprovement.

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CONTENTS

PREFACE v

OPENING SESSIONChairman: V Teixeira Lopo, President CIMPOR

OPENING ADDRESS—ENERGY POLICY OF THE COMMISSION OF THE EUROPEANCOMMUNITIESF KINDERMANN, Commission of the European Communities

2

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

6

FIRST SESSIONChairman: Professor Veiga Simao, President of LNETI

ENERGY SAVING AND ENVIRONMENTAL IMPACT IN THE CEMENT INDUSTRYA SOARES GOMES, CIMPOR, Cimentes de Portugal, Portugal

16

ENERGY OUTLOOK IN WEST GERMANY’S CEMENT INDUSTRYA SCHEUER and S SPRUNG, Forschungsinstitut der Zementindustrie, Düsseldorf 30, FederalRepublic of Germany

20

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

29

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

42

DISCUSSION 49

SECOND SESSION—PART 1—SPECIFIC TECHNOLOGIES AND CEC DEMONSTRATIONPROJECTSChairman: J Sirchis, Commission of the European Communities

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT RECOVERY INCEMENT PLANTSE STEINBISS, KHD Humboldt Wedag AG, Cologne, Federal Republic of Germany

52

DISTRICT HEATING BASED ON WASTE HEAT FROM CLINKER COOLER 64BO AHLKVIST, Cementa AB, Sweden

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

69

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

74

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

81

DISCUSSION 86

SECOND SESSION—PART 2—ENGINEERING AND ENERGY MANAGEMENT

‘HOLDERBANK’S’ ENERGY MANAGEMENT IN THE 1990sM BLANCK, ‘Holderbank’ Management and Consulting Ltd, Holderbank, Switzerland

90

ENGINEERING AND ENERGY SAVINGSJ DUMAS, CITEC, Guerville, France

102

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

112

HIGH ENERGY SAVINGS THROUGH THE USE OF A NEW HIGH-PERFORMANCEHYDRAULIC COMPONENT THE K-TECH PROCESSM 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 INDUSTRYT M LOWES and K W BEZANT, Blue Circle Industries plc, Greenhithe, Kent, United Kingdom

136

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

144

DISCUSSION 148

THIRD SESSION—RODND TABLE DISCUSSIONChairman: Professor Mario Nina, University of Lisbon K W Bezant, BLUE CIRCLE, UnitedKingdom F Aellen, HOLDERBANK, Switzerland Professor G Parisakis, University of Athens, GreeceJ Sirchis, Commission of the European Communities E Steinbiss, KHD, BR Deutschland HTakakusaki, NIHON CEMENT CO, Japan

152

CLOSING SESSIONChairman: V Teixeira Lopo, President of CIMPOR

CONCLUSIONS 158

vii

D QUIRKE, CEMBUREAU CEC, Ministry of Industry

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LIST OF PARTICIPANTS

INDEX OF AUTHORS 189

viii

160

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OPENING SESSIONChairman: V Teixeira Lopo, President CIMPOR

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OPENING ADDRESS“ENERGY POLICY OF THE COMMISSION OF THE EUROPEAN

COMMUNITIES”

F.KINDERMANNHead of Division

Commission of the European CommunitiesDirectorate-General for Energy

Technology DirectorateProgramme 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 Parisin 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 veryimportant brick for the construction of a real Community and one could even say that a good deal of theintegrated 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 thefirst oil crisis back in 1973. Until then, the energy sector in the Community was characterised by twelvedistinct national markets with a matching number of national policies which were more or less coordinatedon 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 substituteoil and to reduce the dependency of the Community. Therefore, alternative energy sources, solid fuels andenergy efficiency, played a very important role, and it should be noted that the latter two are of very greatImportance 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 energyefficiency raised by ±20%. This forced the Commission to propose new targets for 1995, which wereadopted by the Council in September 1986.

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I will not go into these in great detail as we all know very well that, since then, conditions on the energymarket have changed drastically: oil prices went down, as did coal prices on the world market; natural gas ispressing for a higher market share; and in some countries, nuclear energy continues to expand. In additionto this, there is more and more concern about the environment and particularly about the so-calledgreenhouse effect. For these reasons, I would like to mention today only three of the present targets whichare 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 ofeconomy 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 thebeginning. Yet, importance shifted from aspects of substitution and economics to the protection of theenvironment. 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 after1992. Energy is an area where this transition now has to be made in order to have the integrated Europeanenergy 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 initiativesin this field have been launched since the beginning of 1989. These include new schemes for greater cross-frontier trade and competition in the gas and electricity sectors, a mechanism for taking into account theEuropean dimension In the planning of major energy investments, and a new system allowing thetransparency 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 conciseframework for an effective Community energy policy. Therefore, a new review of longterm energyprospects is at present underway, i.e., the 2010 study. A first disscussion paper, entitled “Major Themes inEnergy to 2010” was realised by the Commissioner for Energy, Mr Antonio Cardoso e Cunha, at the WorldEnergy Conference in Montreal last September.

As the Commissioner said in Montreal, the essential question facing all of us is the following: “Can wecontinue to develop the world’s energy supplies, on a secure and economic basis, sufficient to maintaineconomic growth while at the same time ensuring that the global environment is protected and indeedimproved?” 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 pathsuggests a way of controlling energy consumption and its environmental impact whilst maintainingeconomic growth—in other words, meeting the challenge of sustainable energy growth. In the monthsahead, the Commission will refine its analysis, taking into account the reactions in the Community andInternationally, 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 thisissue recently at the world Energy Conference in Montreal. But we cannot afford either to neglect the moretraditional concern of energy policy makers, that of security of supply. This is particularly true at a timewhen the world’s need for oil and other energy supplies continues to grow steadily month by month. Action

OPENING ADDRESS 3

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must be taken to curb this trend in order to preserve as far as possible our energy resource base and toprotect the global environment.

With these two fundamental concerns in mind, it is quite clear that the major priority will have to begiven to energy efficiency. In order to reduce the growth in energy consumption and the associatedpollution.

Thus, the political target is set, and all possible actions have to be put in hand to reach it. Of course, thiscovers political and financial measures as well as technology but for reasons of time, I would like toconcentrate on the latter one.

An excellent technical base to build upon has been created by the Community’s energy demonstrationprogramme 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 presentedduring the course of the next two days. But, in order to let you have an idea of what is involved, I wouldlike 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 1,698 738 43.5Total aid (MECU) 881.7 327.7 37.2

These figures prove that in the past, the Community already gave the appropriate attention to all thepossibilities of saving energy and improving energy efficiency. Let me just say that the main technical areaswere, and still are:

– Buildings– Transport– Industry

The demonstration programme, as it stands now, has pratically come to an end. An independent evaluationwas carried out last year which highlighted the remarkable results obtained in the different areas, but also saidthat much more should be done to assure a widespread use of the results, and to match the new targets forenergy at the beginning of the next century.

The Commission adopted this line and, consequently, proposed to the Council that the replacement forthe existing demonstration and hydrocarbon technology scheme should be the THERMIE programme, a newprogramme for demonstrating new energy technologies and promoting their commercialisation in theEuropean market. As for the current programmes, THERMIE will concentrate on the state beyond R&D byproviding risk finance for the testing of new energy technologies on a nearly commercial scale. It willhowever, be more selective than its predecessor schemes and give more emphasis to the promotion andreplication of successfully demonstrated technologies. The current plan is that the Energy Council and theEuropean Parliament should give their consent to this new programme in time for it to start at the beginningof next year.

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THERMIE will cover a wide range of energy technologies including most renewable energies and energyefficiency technologies, as well as clean coal combustion and hydrocarbon projects. These technologies willcertainly 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 theCommunity 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 THERMIEprovides 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’sproblems and is ready to take its responsability.

OPENING ADDRESS 5

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A POLICY OF ENERGY EFFICIENCYSPEECH 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 energyconsumption. If this is accomplished, it will represent:

– An annual saving of at least 2 million tons equivalent of oil (14 million barrels), corresponding tosomething 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 toimprovements in the quality of the environment; there will, moreover, be an increase in the competitivenessof the economy in general.

To these results would have to be added the internal and external effects of these moves to diversifysources, 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 aconcerted 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, financiallylimited activities. This is a broad characterisation of the system of energy demand, a system requiring notonly 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;

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– 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 economicactivities 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 frameworkand 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 instrumentscontribute overall to providing a reply to many of the questions which are raised in a continuing policy ofenergy efficiency:

– A more exhaustive study of the resources of the country, including not only renewable energy but alsothe 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 useof 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, whofinance 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. SIURE incentive system for the rational use of energy2. The Community programme VALOREN3. The Community programme of pilot studies in the field of energy4. PEDIP

II) REGULATORY INSTRUMENTS

1. Regulation of independant production of electrical energy2. Regulation on the management of energy consumption3. Regulation on the thermal characteristics of buildings

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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 stockof the situation regarding these instruments in the two years of a coherent energy policy which has gonehand 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 inMay 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 twounderway (May and September of this year) the system has already proved that it is much better adapted tothe 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 yearsof 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 amere 31%.

. There are already 30 applications in the area of feasibility studies (an area not considered before). Therehave been 8 approvals and 10 are under consideration. Of the 30, 25 relate to cost control and plans forrationalization of energy;

The diversification of sectors and activities is manifest in those projects which have been approved, withemphasis 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 ofoil, corresponding to Esc. 911m in foreign currency.

In geographical terms, it is the regions of the centre and the north which show a more entrepreneurialspirit, if we consider the level of investment and subsidies which have been given. Stange to say, it is theLisbon 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 investmentassociated 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 financingthrough the VALOREN programme, as long as the operations come within the terms of reference of theprogramme.

I would like to take this opportunity to announce that the whole community and national process has beencompleted, allowing for joint financing of SIURE through PEDIP, in the case of applications which cannotbe included in the VALOREN programme, but which relate to the operations to be developed in theextracting and transformation industries.

In this way, there will be close on Esc. 2.2bn available between 1989 and 1992 as reinforcement of thebudget 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 smalland medium industrial and services companies. The aim is above all to stimulate regions of variouspotential renewable energy sources.

The programme has been operative from October 1987 for applications for public or comparableinfrastructures.

The VALOREM programme can, as has been seen, provide joint finance for incentives which are takenthrough SIURE, as long as the operation is included among its objectives, in terms of investment, budgetand others regulations. The joint financing began in 1988, immediately after the first applications for SIUREfunding.

The committed funds in this operation of the VALOREM programme valid until the end of 1991, wereEsc. 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 Northand Centre, wich show greater dynamism and which have already gone beyond the forecats, while theAlentejo, 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, stalksfrom vines, biogas…) is the source of the largest number of applications. These have already gone beyondthe 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 notcome through yet. These projects are already sufficient to take up all of the funds available for this area. Forthis reason, and also because the average duration of these investments goes beyond the end of 1991 havemeant that studies are underway with the Portuguese Small Hydro-Power Association to find alternative

A POLICY OF ENERGY EFFICIENCY 9

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ways for the VALOREM programme to be associated with the investment which was caused by the newlegislation regarding the independent producer.

The VALOREN programme has been available as finance for important actions involving energy sourceswhich are part of the country’s natural resources and the technologies which are associated with them, aswell as information relating to the possibilites of rational use of energy (for example, through finance forthe IAPMEI “Energy-bus”).

The steady increase in the proportion of energy consumption in the GPD, as well as the recent boom inconsumption, bearing especially on domestic consumption and services, has led to the VALORENprogramme 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 theEuropean Community Commission. It is at the heart of this seminar and since 1975 has been responsible forfinancing important projects in various energy sectors during the precompetition stage.

It is also the Community programme which is best-known among Portuguese industrialists, according toa 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 thePortuguese entrepreneurs, in conjonction with Universities or national laboratories have made applicationsto the programme.

Since great care always been given to the choice and preparation of good projects, the percentage ofapprovals has always been high, and this has allowed us to get support for a percentage which has alwaysbeen 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 toPortuguese projects, representing 22% of the total investment of nearly Esc. 11.5bn. However, in the lasttwo 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 tosolid fuels (that is, carbon fuels), in which, understandably, we saw only 3 out of the 4 projects approved, thegrants 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 ispresented here today. Apart from its innovation in European and Community terms, there are two aspects tothe projects which are worthy of mention here.

Firstly, there is the adoption and adaptation of a Japanese technology for the cement industry which is ofgreat interest in the energy sector.

Secondly, there is the system of recovery of heat from gases from the furnace exhausts, which will alsocontribute 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 THERMIEprogramme, which draws on a different philosophy, due in large measure to the suggestions which we putforward.

In this way, innovatory projects will continue to be supported, with an assessment procedure which ismore rigorously controlled. Moreover, THERMIE will open up the possibility of support to projects alreadypresented, where these are put forward in new contexts, geographical, economic, social and energy orientedwithin, 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 projectsand 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 Communityprogramme is the part of SIURE which allows for incentives for demonstration projects and pilot studies, aswell 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 riskinvolved 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 productioncosts for small units and stimulations could lead to 6.500GWh/year being made available. This led to thenew legislation, which is innovatory above all in terms of the full and rational legal framework in which thisactivity can now be undertaken.

The recent law on production is applicable to all forms of the production electricity from any renewablesource, or from recycled thermal effluents. However, in the early days up to the present, the speediest and mostexciting 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 thisoccasion 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 Generalof SEARN. The difficulties in the management of water resources which this avalanche has created are notdifficult to imagine.

The 370 requests which have a solid foundation and obvious know-how of the field and his use representclose on 1.015MW, greater than the biggest power station In Portugal (Alto Lindoso, which generates625MW). Forecasts point to a production of approximately 4.025GWh, i.e. around 20% of the domesticelectricity production in 1988.

The authorisation process is not limited to the use to which the water is to be put. Among other things, itis essential that the interested parties cleraly justify their technical and economic aims; that there should beno other intentions for the same site; and that different uses are not being considered for the same waterresources.

As for any overlaps, in terms of requests made by different groups for the same site, the decision onwhich takes priority should not be based simply on legal points. We have found that in many cases asolution has been or is being found through discussions with the interested parties. There have also beenexamples or collaboration from the official services involved.

Given the large number of interested parties—companies, local authorities and individuals—and giventhe variety of motives know-how and financial capacity, I consider it of paramount importance to encourageall forms of collaboration which are being found. This applies to the equating of interests, technicalexpertise and management of the resources in question.

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I would like here to draw attention to the creation of the Portuguese Association of Small HydroProducers. This I consider to be indicative of the dynamism of the sector and the professionalism andenthusiasm of those involved.

The initial members of the Association bear the responsability of making it a real partner In the dialoguebetween the various entities in the sector. The Association must consider all applications from would-bemembers, and should even encourage those who work in the sector and are interested in their activities forwidely differing reasons. The question of how representative the Association happens to be is fundamentalto relations with third parties and for this reason, with in the Association, mutual understanding andinterchange of ideas among the members become much more important. Should this spirit prevail I have nodoubt 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 sectorwhich is underway in our country.

As far as the use of small power stations for the production of electricity is concerned, all the 6 requestsfor authorisations which have been handed in to the Office of the Director General of Energy relate topremises destined for the generation of heat and electricity. The fuels to be used are forest waste in 4 casesand gas in each of the other two. The total power potential is around 130MW, with a forecast annualproduction of the order of 800GWh. This demonstrates how much greater is the potential of these systemsthan 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 CIMPORproject, with its total close on 9MW, For theses projects, no authorisation for electrical installations wasnecessary 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 laydown the structures for operations which will hopefully be undertaken by the major electrical energyproducers, 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 thecountry will not just go away; and two, that the entitles involved are not just the State and those on thesupply side. Major consumers must also bear the responsability of bringing about a dowturn in consuptionand a diversification of sources.

Seen from this angle, there are 106 rationalisation plans which have been submitted for approval to theOffice 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. After5 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 toawake the spirit of collaboration among those who run the companies in the sector, since they are the oneswho will benefit first and foremost from the new procedures for management of energy deriving from thelegislation. The fact that applicants for state aid must fulfil the regulations has also helped to spread on themregulations.

It has been recognised that the greatest possible cost control should be exercised over investment anddevelopment plans in the energy field. For this reason, the costs of auditing can be in part offset by

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subsidies from SIURE, as long as methods and content correspond to the models prepared by the Office ofthe 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 ofconsumption and the infrastructures necessary for the management of energy in premises where it isconsumed. 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 mortgagingthe future of energy.

These regulations, which should be on the statute books from January 1991, draw in their train furtherregulations on the characteristics and dimensioning of active systems of air conditioning in the samebuildings. These regulations are being drawn up in the Council of Public Works, Transport andCommunications.

The great challenge now is to get them known among owners, designers and builders, and also in thetraining 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 turnkeyprinciples and to this and the Office of the Secretary of State of Energy is actively promoting the creation inPortugal 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 inthe process of setting up.

A system of finance specifically for projects which generate energy savings is different from leasingoperations, from credit operations involving suppliers of equipment and from other forms of finance. Thefundamental differences are threefold:

. The contract is specific to the supply of a consultancy service and technical assistance, a financialpackage 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 foroperating the system on site for the duration of the contract;

. The investment, along with associated services and charges, is paid off through the measurement ofenergy saved, taking the initial situation as a point of departure. The return is normally within theparameters of the savings achivied.

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Altough there are no public funds for this, the Office of the Secretary of State, along with the EuropeanCommission, is actively seeking the structure and support mechanisms for this system of financing. To thisend, these groups can apply for support through SIURE, and it is hoped, through the VALORENprogramme. At this time, ways of channelling venture capital available through PEDIP are also being activelysought for this type of company.

This then is the situation regarding the major instruments created by the Office of the Secretary of Statefor Energy with a view to improvements in energy efficiency. And over and above this attempt to show thecountry what is happening—as well as the European Community represented here—I wished to takeadvantage 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, toCIMPOR. This company realised at a very stage that is needed to manage its energy consumptionefficiently, and to this has: a) diversified its energy sources by using old tyres and even coal (which wasthen made available for other consumers); b) recovered thermal effluents from furnaces, not only inabsorption 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 throughmanagement 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 madeavailable to other companies and other countries. Moreover, the company has used in the best possible waythe 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 samespirit should become a concrete reality in other companies and consumers in Portugal. By the same token Ihope that the work begun today will be crowned with success.

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FIRST SESSIONChairman: Professor Veiga Simao, President of LNETI

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ENERGY SAVING AND ENVIRONMENTAL IMPACT INTHE CEMENT INDUSTRY

ANGELO SCARES GOMESCIMPOR, Cimentos de Portugal, Portugal

SummarySince 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 facingmany obstacles in the acquisition of used tyres, due to the lack of appropriate legislation andmechanisms. The low amount of tyres burned is the main cause of the present reducedeconomic profitability of the installation.

1.INTRODUCTION

The subject of this address has been deliberately requested within the context of the general outlineconceived in the initial stages of organisation of this Seminar. The concern to include this subject in theprogramme is understandable. Currently questions related to the environment are of great importance, andthey 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 theenvironment 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 ofrelative 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 aresult of the 1973 and 1978 oil crises.

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For this reason we now propose to meet the request that has been made by presenting below someconsiderations on this subject, starting with the recent experience of a tyre burning installation atCIMPOR’s Maceira cement plant.

In the course of several years of work it has become apparent that in various sectors the ability of the cementindustry to absorb certain waste which would affect the environment or demand considerable costs to beeliminated 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 italways 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 dry-process 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 inexistence in Europe indicated the possibility of consumption of used tyres in the kilns in the near future at15% of the total thermal energy, which meant a consumption of between 7500 and 8000 tons per year, ineach kiln.

It was foreseen that a sufficient quantity of used tyres would be available to use regularly with one kilnand that eventually the burning of tyres would be extended to the second kiln. This was based on the factthat the quantity of tyres produced in Portugal was calculated at about 20000 t, with an upward trend. Ineconomic terms, the scenario envisaged at the date that the decision was made (1984) was as follows:

Coal price (at factory prices) 9760 Esc/tonTyre cost (at factory prices) 5000 Esc/tonAnnual Saving (Gross) 30 million EscInstallation Costs 90 million EscPayback 3 years

So from the economic point of view the investment appeared quite interesting. The decision for itsaccomplishment 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.

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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 stablework, although the annual average is slightly lower at 10%. The kiln has a stable working pattern and thequality 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 (about2%).

– A greater degree of corrosion than is normal has occurred inside the gas conditioning tower, as aconsequence 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-oiland 5848 tons of tyres.

TABLE 1. Tyre burning economic situation

Clinker outputton

Thermalconsumptionkcal/kg

COAL TYRES Operating profit×1000Esc

Payback

Cost×1000Esc/ton

Consumptionton

Cost×1000Esc/ton

Consumptionton

1984100% COAL

392300 825 9.76(1)

51000 – – – –

Forecast (based1984) COAL &TYRES

400000 825 9.76(1)

45200 5.0(1)

7000 30000 3 years

1988REALFIGURES

395748 843 7.98(2)

52091 6.69(2)

5848 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 provisionalestimations made in 1984.

It can be seen that in 1988 the annual profit resulting from tyre burning was below the level forecast in1984, 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 factoryburned only 5848 tons, due to lack of supply of tyres.

– Increase in the thermal consumption of 18 Kcal/kg of clinker.

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– 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. CIMPORnegotiates with those companies a certain price for the acquisition of tyres, delivered to the factory, as wellas the quantities required. Unfortunately, those quantities are never achieved. It is impossible to find such anenormous quantity of tyres concentrated in one place. Tyres are scattered widely by geographical locationand are available from companies and organisations, thus making collection difficult, slow and inevitablyinefficient.

However, a curious situation is now happening. Some of the organisations that until recently gave thetyres freely are now demanding to be paid for the same tyres. The factory’s demand itself has led to theattribution of a certain commercial value to a product that before had absolutely no value. In practical termsthis 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 ofacquisition of the tyres, but even if it were possible to pay the suppliers, it is still doubtful whether, in themedium term, the quantities would increase. Probably it would only cause an increase of the prices at theorigin.

So far, CIMPOR has not been able to acquire the necessary quantities to achieve viability of theinstallation, nor has the country been able effectively to reduce the pollution caused by the old tyres. Theproblem 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 thismatter, the desired result will only be accomplished if the state takes part, through the CentralAdministration, 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 cannotbear the costs involved in the complex organization of collection of the tyres which are spread all over thecountry.

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ENERGY OUTLOOK IN WEST-GERMANY’S CEMENTINDUSTRY

A.SCHEUER and S.SPRUNGForschungs institut der Zementindustrie,

Tannenstraße 2, 4000 Düsseldorf 30Federal Republic of Germany

SummaryThrough 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 cementin 1988. To a limited extent, energy savings are today possible by the use of secondaryconstituents in cement grinding or by optimizing the process technology in the preheating,burning and cooling of the cement clinker. The technological possibilities for waste heatutilization, on the other hand, are already largely exhausted. Sophisticated process technologyshould therefore aim at a reduction in the heat loss through the kiln wall, e. g. by theconstruction of short rotary kilns with tertiary air duct and precalciner.

Due to increased automation and measures for an improved environmental protection theelectrical energy consumption rose from 0.32 GJ/t of cement in 1960 to 0.42 GJ/t of cement in1988. When modern roll mills are used energy savings of up to 50 % are conceivable in thegrinding of the raw materials and of up to 35 % in the grinding of cement. Further savings arepossible with the modern cyclone air separator, the vertical impact crusher, the optimum designof 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 madeto lower the energy consumption in the manufacture of cement (1). By using advanced rotary kilns andshutting down older kilns the fuel consumption fell for instance from 4.8 GJ/t of cement in 1960 to 3.0 GJ/t

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of cement in 1988. Due to a greater degree of automation and measures to improve environmentalprotection the demand for electrical energy, on the other hand, rose from 0.32 GJ/t of cement to 0.42 GJ/t ofcement (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).

Unit 1960 1970 1980 1988

Cement manufacture 106t 24,6 37,5 33,1 24,4

Fuelenergy requirement per ton of cement GJ/t 4,8 3,8 3,4 3,0Electricalenergy requirement per ton of cement GJ/t 0,32 0,34 0,39 0,42

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 andc) the preparation (milling) of the clinker to cement.

Under the headings

a) energy savings through product innovationb) energy savings through process optimization andc) 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 anoptimum use of energy, a demand which is, after all, of the greatest importance to the economics ofboth the individual business and the national economy as a whole. However, the realization ofmeasures should not only be judged on whether these are technologically feasible or not. Decisive are alsocost considerations in relation to the results achieved. Furthermore, in future greater care has to betaken to ensure that a branch of industry is not put under cost pressure by governmental regulationsimpairing 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 theturn of the century portland-slag cement and blastfurnace cement have existed as further standardized typesof cement containing as a third component 6 to 35 % or 36 to 80 % of glasslike set and latent hydraulicgranulated blastfurnace slag. Nowadays also limestone and flyash are used as constituents formanufacturing portland composite, portland filler and port land flyash cements. In addition, in the FederalRepublic of Germany oil-shale and portland pozzolana cements have been made for some time. But table 2shows that in 1988 owing to market demands portland cement still accounted for 71.7 % of the totalproduction. Only 28.3 % of the cements contained other main constituents besides clinker. Altogether forthis about 4 Mio. tons of secondary constituents were needed. In principle, the use of secondary constituents

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instead of clinker brings about significant savings in fuel energy as well as electrical energy in the clinkerproduction. On the other hand, cements with secondary constituents have to be ground to a greater finenessthan a portland cement of the same strength class. Furthermore, the secondary constituents must be driedand additional transportation costs are incurred, in turn lowering the energy savings. It also has to be bornein mind that the market demands on the utility properties of the cements and an increased quality awarenessregarding durability of concrete do not allow an unlimited use of secondary constituents and addedmaterials in the manufacture of cement and concrete.

Table 2: Cement type percentage of total sales on the home market in 1988.

Portland cement 71,7 %Portland-slag cement 7,3 %Blastfurnace cement 15,4 %Oil-shale cement 1,7 %Portland-pozzolana cement 0,5 %Other cements 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 theFederal 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 orB are equipped with a calcinator, 3 in addition with a tertiary air duct. The average throughput of thevarious 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 coolerand 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 cliRotary kiln 400 315 500Cooler 500 500 500

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Preheater type Cyclone Cyclone Grate

Cooler type Grate Counter-flow Grate

Mean capacity in t/d 1700 3050 1000

Preheater 875 855 350Theor. heat requirement 1760 1760 2220Total heat requirement 3535 3430 3570

Table 4 shows how the fuel energy consumption of a rotary kiln with cyclone preheater increases ordecreases with the source of the energy loss becoming bigger or smaller. Accordingly, a waste gas enthalpyloss of the preheater rising by 10 kJ/kg cli must be compensated with approximately 8 to 9 kJ/kg cli of fuelenergy. Heat losses through the wall of the preheater affect the fuel energy consumption less and requireonly 0.2 to 0.8 times the fuel energy. In contrast, losses of heat through the wall in the burning zone (thelowest 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 0,87Energy loss through wall of cyclone stage 1 0.222 0,443 0,764 1.18Energy loss through wall of rotary kiln and theor. heat requirement 1,18Energy loss of the cooler 1,46

rotary kiln) have to be compensated with about 1.2 times the fuel energy. This factor is also to be used forassessing altered reaction enthalpies of the clinker. However, with the usual design of the kiln the greatestinfluence on the fuel energy consumption is exerted by the cooler. In relation, a change in the cooler energyloss leads to a change in the fuel energy consumption by almost 1.5 times (2). Thus, heat recovery in thecooler is the most important parameter for fuel energy consumption. For this reason, most optimizationmeasures 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 percentageof primary air in the total combustion air is normally smaller than 10 %. Measures to improve heat recoveryin the clinker cooler therefore aim at a further drop in the primary air proportion to about 5 % with at thesame time low NOx emissions through the use of advanced rotary kiln burners as well as at lowering theproportion of the false air through the installation of sophisticated kiln seals. In grate coolers heat transfer maybe further improved by a higher clinker bed in the recuperation zone, e.g. by narrowing the grate width orby lowering the number of thrusts. Furthermore, heat transfer may also be improved by grate plates withhorizontal air outlet. If there is a chance to use the enthalpy of the cooler waste air, the design of the coolershould be such that recuperation zone and cooling zone are separated and each zone is optimized

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individually. On the other hand, with coarse clinker or clinker with a wide grain size distribution theoptimization of tube coolers or planetary coolers still presents difficulties. Cooler optimization is at presentcarried 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 asubstantial proportion of the total energy losses. Accordingly, to compensate the heat losses through thewall of rotary kilns different proportions of fuel energy are needed. Due to higher energy inlet, high heatloss through the wall therefore also leads to higher waste gas energy loss of the kiln (2). An increase in theenergy loss through the wall of the rotary kiln must therefore be compensated by an overproportionally highamount of fuel energy.

Heat loss through the wall of the rotary kiln is mainly governed by the kiln design and its specific burningprocess. Fig. 1 (2) gives the heat losses through the wall of various kilns found in field tests in dependenceon their clinker throughput. The figure illustrates that kilns with large clinker throughputs show smallerspecific heat losses through the wall than kilns of smaller capacity. These heat losses are also smaller inkilns with tertiary air duct than in those without tertiary air duct, since in the former the operation processallows substantially smaller dimensions. Thus figure 1 makes it quite plain that by shutting down smallerkiln 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 thecapacity 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 thewaste gas enthalpy is transferred to the kiln feed and thus recovered for the process. In addition to the gas massflow, which in turn is governed by the fuel energy demand as well as by the air rate, the efficiency of thepreheater is mainly dependent on the dust cycles in the preheater. It is normally between 50 to 65 % andmay be markedly increased by the installation of additional dip tubes. Fig. 2 (2) indicates that by increasingthe separation efficiency of both lower cyclone stages from 60 to 80 % each, the preheater energy loss maybe cut by about 0.15 MJ/kg of clinker. In the past the installation of dip tubes was successfully effected innumerous plants.

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

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Savings in electrical energy

The main part of the electrical energy requirements is accounted for by the milling of the cement (3), inaddition, 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: Bundesverbandder Deutschen Zementindustrie).

Energy requirement in kWh/t

Raw material preparation 10 to 30Clinker burning 15 to 25Cement grinding 30 to 80Other < 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 doneby 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 ofwaste gas may be utilized for the preparation of the raw material. This is the reason why this size reductionmethod is above all successful in the mill drying of raw material and coal. As compared with ball mills,

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

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roller mills may achieve up to 50 % of energy savings for the mill drying of raw material. For the milling ofcement the situation is similar, although here the energy savings are reduced with increasing wear and mayeven turn into an excess energy consumption. In addition, special measures are needed to safeguard theutility 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 cementgrinding. 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 cementproperties (water demand) energy savings of up to 35 % are possible in a high-pressure grinding cycle withopen-circuit ball mill placed behind. However, for quality reasons a secondary grinding in a ball mill bysome 1,500 cm2/g is nowadays still necessary (5).

Fig. 3 shows the energy demand of the grinding methods mentioned in dependence on the specificsurface area (5). The dashed lines relate to the secondary grinding in a ball mill of grinding feed from high-pressure grinding rolls operated in closed-circuit. The figure indicates that to grind cement to a fineness ofsome 2,000 cm2/g in high-pressure grinding rolls an energy demand of only some 9 kWh/t of cement wouldbe needed. A secondary grinding by about 1,500 cm2/g requires additionally 18 kWh/t of cement. The totalenergy consumption for a grinding to 3,500 cm2/g would thus amount to about 27 kWh/t of cement. For acorresponding grinding in a hybrid mill roughly the same energy is required. However, the placing of a ballmill behind a high-pressure grinding roll cycle could lead to higher savings in energy, provided the utilityproperties of the cement allow a higher fine grinding in the high-pressure roll mill and thus a lowersecondary grinding in the ball mill. From this follows that a separate operation of high-pressure grindingroll mill and ball mill would be best to ensure quality optimization and a reduction in the energyconsumption. However, further investigations are still necessary.

A further possibility for the pre-grinding of the clinker is offered by the vertical impact crusher, alsoknown as David crusher, in which the mill feed is autogenously crushed. As against a non-optimizedgrinding plant with ball mill, energy savings of 14 and 24 % were achieved (6).

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

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Installation of advanced separators

A separator in a mill system serves to relieve the mill of already finely ground cement proportions. Therelated result in energy savings is the higher, the more accurately the separator divides the not yet fullyground feed in fine and coarse portions. The optimization of the separator has led from the traditional rotaryair separator via the conventional cyclone air separator to the cyclone air separator with specially developedcircumferential screens. By replacing the rotary air separator with the modern cyclone air separator withcircumferential screens and a simultaneous optimization of the ball mill 14 to 28 % of the total energyconsumption needed by the whole grinding plant may be saved (7). Naturally, when considering thesefigures, not only the exchange of the separator has to be taken into account, but also the optimization of theball 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 cyclonepreheater to the higher waste gas volume flows. This caused the pressure losses in the cyclone preheater andthus the specific electrical energy requirements of the ID-fan in some cases to double or to increase evenmore. In redevelopment work the gas cross sections were sometimes enlarged by 100 % and in addition thepressure losses could be reduced by aerodynamically adjusted geometries. In some cases the specific energyrequirements 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 longtradition. Up to the 1950s and in some cases even the 1970s especially designed generators were inoperation. For economical reasons the shift to the energy-conserving rotary kiln with preheater brought theuse 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 of350 ºC only about 18 % of the decoupled heat flow may be recovered in the form of electrical energy andthus 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, assince the introduction of the rotary kiln with cyclone preheater is has been the state of the art to use in thiskiln system the waste gas after preheater to dry the raw material, the granulated blast-furnace slag and thecoal. Moreover, in many cases the kiln feed is already heated in the mill to about 80 ºC. Since in the FederalRepublic of Germany the raw material moisture rates are comparatively high (in some cases up to 20 %) thewaste gas temperature on leaving the mill drying is frequently as low as about 100 ºC. Due to this the wasteheat 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 twoadditional 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. Thetechnological possibilities for waste heat utilization are thus already largely exhausted.

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY 27

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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 losseswith high-efficiency collectors is unprofitable (8).

Futher energy conserving potentials are offered by an optimized design of electric drive units andnetworks 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, withthe use of the pulse generators in the installation and redevelopment of electrofilters savings in electricalenergy of up to 50 % may be achieved. An indirect energy conservation is also effected with an increaseduse of current from power plants with favourable efficiency rates during off-peak hours.

REFERENCES

(1) Energiepolitische Praxis in der Steine-und Erden-Industrie. Bundesverband Steine Erden e. V., Frankfurt amMain 1987.

(2) ROSEMANN, H.: Theoretische und betriebliche Untersuchungen zum Brennstoffenergieverbrauch vonZementdrehofenanlagen mit Vorcalcinierung. Schriftenreihe der Zementindustrie 48 (1987).

(3) KUHLMANN, K.: Verbesserung der Energieausnutzung beim Mahlen von Zement. Schriftenreihe derZementindustrie 44 (1985).

(4) SCHNEIDER, G., G.GUDAT and V.SCHNEIDER: Betriebserfahrungen mit Gutbett-Walzenmühlen bei derZementmah lung. Zement-Kalk-Gips 42 (1989) No. 4, p. 175–178.

(5) ROSEMANN, H., O.HOCHDAHL, H.-G.ELLERBROCK and W.RICHARTZ: Untersuchungen zum Einsatzeiner Gutbettwalzenmühle zur Feinmahlung von Zement. Zement-Kalk-Gips 42 (1989) No. 4, p. 165–169.

(6) BINN, F.J., and W.BEESE: Einsatz eines Prallbrechers zur Vorzerkleinerung von Zementausgangsstoffen.Zement-Kalk-Gips 42 (1989) No. 4, p. 170–174.

(7) MÄLZIG, G., and B.THIER: Zerkleinern und Homogenisieren. Verfahrenstechnik der Zementherstellung.Verein Deutscher Zementwerke e. V., Düsseldorf 1987.

(8) HOCHDAHL, O.: Brennstoffe und Wärmewirtschaft. Verfahrenstechnik der Zementherstellung. VereinDeutscher Zementwerke, Düsseldorf 1987.

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OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRYJESUS GARCIA DEL VALLE AND ALEJANDRO TORRES

ASLAND TECNOLOGIA, S.A.P de la Castellana, 184, 7

28046 Madrid, SPAIN

SummaryThe 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 isuncertain. 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 newstagnation. Projections for year 2000 are very uncertain, depending upon the economic issues ofthe region. Projects for new capacity extensions will be scarce in the upcoming years unlesseconomic troubles are overcome.

Energy consumption in Latin America Cement industry varies in a wide range, according tothe type of process, efficiency of installations, technology, etc. Some countries have improvedenergetic efficiency, but in many cases only little efforts for fuel and electricity savings havebeen accomplished.

In spite of financial difficulties, investments to improve energy efficience are advisable, inorder 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 andusage 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

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seems that Latin America is not able to iniciate a reasonable period of development. The next table showsthe 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 −0.1% −2.0%Bolivia −1.4% −2.7%Brasil 1.8% −0.8%Chile 2.8% 1.2%Colombia 3.0% 1.0%Costa Rica 1.0% −0.7%Dominican R. 2.3% −0.7%Ecuador 2.5% −0.3%Guatemala 1.0% −1.5%Honduras 2.2% −0.8%Jamaica −0.8% −1.1%Mexico 3.2% −0.6%Panama −3.1% −1.8%Paraguay 3.1% 0.0%

GROSS DOMESTIC PRODUCT GROWTH

COUNTRY TOTAL PER CAPITA

Peru −1.3% −3.7%Trinidad T. 1.5% 1.4%Uruguay 0.9% 0.2%Venezuela 0.0% −2.2%

The main reasons for such a poor performance fluctuates for the different countries, but neverthelesssome 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:

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TABLE 2

COUNTRY DEBT/GNP

Argentina 60Bolivia 110Brasil 30Chile 90Colombia 40Costa Rica 90Dominican R. 70Ecuador 90Guatemala 30Honduras 70Jamaica 120Mexico 60Panama 70Paraguay 50

FIGURE N 1

GROSS DOMESTIC PRODUCT GROWTH

LAST DECADE YEARLY AVERAGE

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COUNTRY DEBT/GNP

Peru 25Trinidad T. 30Uruguay 40Venezuela 70

2.CEMENT SECTOR. SITUATION AND FUTURE

Cement production in Latin America reached about 85.2 million metric tons in 1988, that is 300,000 MTless than 1987’s figure. Apparent consumption was close to 78.9 millions, slightly under 1987’s, thatreached 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.’sports as destination. Per capita consumption was 181 Kg., while the previous year it had been 186 KG. Theper capita figure drop has been more important than the total consumption decrease due to the highpopulation growth rate (2.4% as average).

FIGURE N 2

LEVEL OF DEBT

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Table n 3 presents the breakdown of these figures by regions. Regional grouping is the same asCembureau’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 7.6 7.7 231CENTRAL AMERICA 25.6 21.2 184SOUTH AMER. EAST 38.3 37.4 183SOUTH AMER. WEST 13.7 12.6 153TOTAL 85.2 78.9 181Source: CEMENTO-HORMIGON and own investigation

The evolution of cement industry during recent years shows a steady growth up to 1980/81, when the percapita 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 arecovery, but 1988 represented a stagnation, perhaps a hint of a coming drop, if economic problems of thezone 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 countriesexperienced 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 arepresented in three scenarios:

– Low: It corresponds to the stagnation of total consumption (79 million MT in 2000), but it means a sharpdecrease 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 hugeuncertainty we have referred to. It is not possible to narrow the gap without lossing a high degree ofreliability.

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY 33

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34 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

FIG

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3

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CEM

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The production capacity of the zone in 1987 was 122.5 million MT. We have calculated this figure usingthe data from the CEMBUREAU Directory, and including the expansion projects undertaken. Itcorresponds 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 intoaccount, the gap between present capacity and consumption is quite big, and indicates a high probability ofthe zone keeping its excedentary position.

Projects for new capacity extensions, thus, will be predictably scarce in the coming years. They will belocalized 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 LatinAmerican 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 energyconsumption. Data in this table refer to unit consumption for the years 1987 and 1988.

TABLE 4ENERGY 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 966 1026 130 128Brasil 997 994 123 125Colombia 1400 1400 125 122Costa Rica 855 855 132 132Cuba n.a. 1434 n.a. 117Dominican R. 1165 1173 127 118El Salvador 1000 975 116 117Guatemala 846 850 116 110Honduras 980 1027 134 131Peru n.a. 881 n.a. 132Uruguay 1335 1334 117 118Venezuela 1200 1200 125 125source: own investigation

As per calorific consumption is concerned, figures vary form 846 Kcal/kg of clinker in Guatemala, to1434 Kcal/Kg. clinker in Cuba.

When considering power consumption, the range goes from 110 Kwh/MT. of cement (Guatemala) to 134kwh/MT. of cement (Honduras)

The differences in calorific consumption lay mainly in the type of process. Wet or dry system process andprecalcination technology are decisive on this subject. In table 5 the breakdown of kilns by types and

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36 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

FIG

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LATI

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CEM

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geographical regions is presented. Data have been elaborated from basic information form 1987 WorldCement Directory (CEMBUREAU). Dry column means dry and semidry processes.

TABLE 5CEMENT 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 49 7 42 0 11270 4345 6925Central America 107 90 17 32 34370 32190 2180S.Amer. East 193 141 52 14 59010 50895 8115S.Amer. West 77 38 39 9 15120 9570 5550TOTAL 426 276 150 55 119770 97000 22770% 65% 35% 13% 81% 19%Average/kiln 281 351 152

TYPE OF FUEL (%)REGION Coal Oil Gas OtherCaribbean 19 76 4 0Central America 0 69 31 0S.Amer. East 26 49 24 0

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

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Capacity and type of fuel

N OF KILNS Clink.Capac. (1000 MT/Year)

REGION TOTAL DRY WET PREC TOTAL DRY WET

S.Amer. West 47 36 16 0TOTAL 21 56 23 0Source: Preparation based on data from the 1987 CEMBUREAU’s “World Cement

Directory.

As it can be seen, in 1987 wet processes represented still a 35% in number of kilns and a 19% in clinkercapacity. Percentage of kilns equipped with precalcinator was a bare 13%. Regional differences areremarkable. I.e., percentage of wet kilns in the Caribbean Bassin was 86%, while Central America recordedthe 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 theMexican 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% ofclinker capactiy corresponds to wet process kilns. The percentage is higher when dealing with productioninstead of capacity, as wet lines are more efficient than dry ones. In Venezuela a 40% of clinker capacitystill lay in wet process, with no incentive to save fuel.

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

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Higher number of dry process kilns has been accompanied with the increase in the average size ofproduction lines. New lines, with modern technology, are usually bigger than older ones. As shown in nexttable, the average capacity was 281,000 metric tons per kiln, according to data from 1987 CEMBUREAUDirectory. While the average size of wet process kilns was only 152,000 MT, the average capacity of dryprocess ones reahced 351,000. This has a double effect on energy consumption figures. Fist, the drytechnology has a fuel saving effect. So, as acutal consumption in wet process kilns investigated varies in therange 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 capacityby 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 asfuel, 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 thehigh costs of liquid fuels derived from the petroleum crisis. But as the table shows, many countries areproved sluggish to keep pace with this trend. So, for instance, the percentage of capacity served with coal isonly 19% in the Caribbean. In Central America, the percentage is negligeable. There is an explanation whendealing with Mexico, but other countries of the zone, non oil producers, are still entirely dependent onexpensive oil imports.

Outside coal, oil and gas, other fuels are starting to be used. The percentage of these fuels according to dataform 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, theefficiency 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 highefficiency separators.

Size of production is also very important in connection with power consumption, as it has been statedbeforehand.

But this is in the field of cement types where the most outstanding results can be obtained. Blendedcement, using additions such as pozzolanas, fly ashes, iron slags, etc., have a favouring effect on energyconsumption, both fuel and power figures.

Addition utilization reduces the percentage of clinker in the production of cement. Some countries havedeveloped the production of this type of cement, reducing the clinker/cement ratio. Table n 6 and figure 7present some examples, the figures corresponding to 1988.

TABLE 6CLINKER/CEMENT RATIO(figures corresponding to 1988)

COUNTRY %

Argentina 90Brasil 79Colombia 82Costa Rica 93El Salvador 95Guatemala 90Honduras 85

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY 39

Uruguay 90

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Some countries show interesting ratios, as Brasil (79%), and Colombia (82%). But many other are mainlyproducers 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 ofpyroclastic materials is becoming more and more important, with more users in Argentina, Chile, Hondurasand other countries.

What will the future be like in energy consumption aspects? In our opinion Latin American CementIndustry should go on the started path. Reduction of energy consumption shall be performed by processimprovements 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 ofblended cements, by itself, may increase cement capacity by a 10/15%, without resorting to important

Fig. 7. Clinker/cement ratio

(figures corresponding to 1988)

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investment outlays. The other are more expensive, but also increase production capacity and may constituteprofitable solutions.

As we explained before, production extensions will not be needed in a general way, but in some countriesexperiencing deficits, new capacities through economic and rational solutions will help to avoid cementdeficits in spite of financial difficulties.

In other countries with cement surpluses, this type of solutions is also wise, as it can contribute tooperation cost reduction, and better employment of existing facilities. A lower utilization of old lines, thathave his operation costs, would also be possible.

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ENERGY OUTLOOK IN THE JAPANESE CEMENTINDUSTRY

YUKIO NAKAJIMASenior managing DirectorNIHON 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 : 8%2.5–3.5 Mton/year : 10%1.5–2.5 Mton/year : 23%0.5–1.5 Mton/year : 51%

smaller than 0.5 Mton/year : 8%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 : 80%SP Kiln : 16%the others : 4%

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2.PROGRESS OF ENERGY SAVING UP TO THE PRESENT.

a) Small and medium-scale, Low-productivity factories were closed, and production concentrated inconveniently-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, werealso greatly contributed to energy saving.

c) Diversification of cement quality such as to blast furnace slag cement and others has had a significanteffect.

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 710Kcal/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 systemhad 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 cementworks as energy sources would be important.

b) New development of process, facilities and materials in terms of higher efficiency and longer lifeshould be continued.

c) Optimization for scale of cement production, process control method, plant location and transport ofcement should be worked out further.

d) Management

– Long term stable operation is a principal at plant management. To achieve this, a strong effort to stabilizequantity 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 preventivemaintenance is required.

– Overall participation included all operators make it possible to improve plant efficiency becauseoperators are actually at the scene and have first-hand experience in the day-to-day working of the plant.

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4.CONCLUSION.

Energy saving is eternal theme. The approach to energy conservation changes with the conditionssurrounding the enterprise and the background technolgy of the times.

For this reason, the international exchange of ideas and methods for energy conservation will becomeeven more important in the future.

Fig. 1. Cement demand in Japan

Fig. 2. Capacity per kiln

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

Fig. 4. Labour productivity and number of employees

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

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

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Fig. 7. Power consumption

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DISCUSSION

DR TOM LOWES, Blue Circle Cement, asked MR A SCHEUER.

QUESTIONYou made no mention of the possibility of using expert systems/high level control and energysavings.ANSWERThis is a good method of improving efficiency but was omitted because of time constraints.

MR TANGNEY, Irish Cement, asked MR NAKAJIMA

QUESTIONDoes the labour productivity figure indicated include contract labour?ANSWERThe labour productivity does not include sub-contractors who are used to reduce the numbersdirectly employed.

MR SAMOUILHAN, CLE France, asked MR NAKAJIMA

QUESTIONRegarding consumption of 700 kCal/kg, is it calculated on a clinker or cement basis and do youinclude additives in your calculation?ANSWERNo, additives are not included.

MR GONCALVES DOS SANTOS, Secretary of State for Energy, Portugal, asked MR SOARESGOMES

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QUESTIONRegarding decreased NOx output, is this due to decreased consumption in energy?ANSWERChanges introduced so far make us sufficiently confident that we can continue consuming tyreswithout any SO2 and NOx damage to the environment. It is true that we have noted somecorrosion in the conditioning tower, which is where gases are emitted. However, this does not leadus 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 therefuse is very expensive and therefore one has to be paid a very good rate by the local authority to justifythe capital expenditure. Furthermore, on the wet process kiln, which was gas emission linked, there was areduction in output of 3% to 5%, so the overall economics depend upon the requirement for using the fullcapacity of the kiln and also the payment from the local authority. It is therefore technically feasible buteconomically unlikely.

MR CASTELA, CIMPOR, Maceira, Portugal—As a supplement to Mr Gomes’ contribution I would liketo comment on our production centre. Burning tyres gives rise to two problems in the cyclone tower and inthe conditioning tower. There is an increase in encrustations, especially sulphur clogging, and we havefound 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 beentaken. 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 1000mg/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 needfor a ball mill in integral grinding. Six months ago CLE developed and started up a new plant in Franceusing the roller press without a ball mill. This plant is producing cement at a capacity of 55 tonnes/hour andthe 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. Ibelieve that new technology, new approaches and new perspectives can be derived in order that theEuropean Community can have a sound policy for the year 2000.

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SECOND SESSION

PART 1—SPECIFIC TECHNOLOGIES AND CECDEMONSTRATION PROJECTS

PART 2—ENGINEERING AND ENERGYMANAGEMENT

Chairman: J Sirchis, Commission of the European Communities

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TRADITIONAL AND ADVANCED CONCEPTS OF WASTEHEAT RECOVERY IN CEMENT PLANTS

E.STEINBISSKHD Humboldt Wedag AG, Cologne, W-Germany

SummaryKiln 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 waterheating. 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 10–35kWh/t (net output). The feasibility of the heat recovery system will be given today only forlarge units above 3000 t/d clinker.

A new method of utilization of waste gas heat is provided by precalcining systems withbypass, in which up to 100 per cent of the kiln exit gases can be economically bypassed and beutilized in a steam boiler, without requiring any cooling.

Further raise in heat recovery efficiency could be achieved by introducing the OrganicRankine Cycles (ORC-Process).

1.INTRODUCTION

Cement plant operators again and again raise the question as to what possibilities there are for utilizing thewaste heat from their kilns. The question becomes particularly important in cases where the scope for theconventional (and thermally very advantageous) utilization of this heat for drying of raw material, coal orslag does not exist. The heat quantities, contained in the waste gases are relatively large and constitute themajor loss items in the heat balance of the burning process. This is true also for plants where considerable

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amounts of bypass gas are extracted at the kiln inlet (feed end) because the gas temperature in this part ofthe system is particularly high.

From the heat balance of a cement kiln with cyclone preheater and 30 % bypass in table 1 it appears thatabout 20–30 percent of the heat losses are due to the pre-heater waste gas and the exhaust air from theclinker cooler (1).

Table 1: Average values of heat consumption for cement clinker burning

heat quantity referred to clinker

kJ/kg %

theoretical heat requirement 1700 50waste gas heat 640 19exhaust air from cooler 400 12bypass gas heat (30 % bypass) 260 8wall heat loss (preheater, kiln, cooler) 230 7heat in clinker discharged 100 3remainder 50 1total 3380 100

In plants with gas bypassing the loss due to this technique may, depending on the amount of gasextracted, range up to 32 percent of overall heat consumption. It is particularly this highgrade heat that opensup fresh possibilities for its utilization. For this reason, in recent years, we have investigated how thevarious waste gas heat quantities can be optimally utilized in separate units. This development is furtherencouraged 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 twoprocesses, however. The drawback is that the waste heat boiler has to be shut down when- ever the kiln isstopped. 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 recoverysystem, 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 heatboilers. And I want to point out that a waste heat boiler should be considered only if there is no otherpossibility 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 cyclonepreheaters. This will depend on the methods and machinery employed. Fig. 1 schematically indicates theprincipal points of gas discharge from the rotary kiln process with precalcination. The waste gases differwith regard to quantity, composition, temperature, pressure and dust content. It is presupposed that thesegases cannot be directly utilized in the burning process.

Table 2 gives guidance in assessing the utilization potential of the waste gases. This utilization potentialof a waste gas flow increases more than proportionally to its temperature. Hence it will always beendeavoured preferentially to utilize those gases which are hottest. Below 100 °C it is generally no longereconomically attractive to utilize the heat.

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Table 2: Characteristic data of utilizable waste gas mass flows

point of gasextraction

designation spec, massflow m3/kg 1)2)

temperature °C underpressurembar

dust content g/m3 1)

scope forutilization

1 preheaterwaste gas

0,6–1,8 280–600 20–80 20–100 drying of: rawmaterial filtercakeblastfurnaceslag coal (inertoperation)steamgeneration

2 preheaterintermediategas

0,1–0,4 500–800 30–70 50–150 drying of:filter cake coal(inertoperation)steamgeneration

3 kiln exit gas(bypass gas)

0,1–0,5 1000–1200 2–10 50–300 drying of:blastfurnaceslag rawmaterial 3) coal3) steamgeneration

4 hot air fromcooler(secondary air)

0,1–0,3 700–900 0.1–0,5 5–200 drying of:filter cake

5 exhaust airfrom cooler

0,4–1,8 150–400 0,1–0,5 5–20 drying of: rawmaterial, coalpreheating of:

Fig. 1: Extraction points for exit gas and exhaust air flows

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point of gasextraction

designation spec, massflow m3/kg 1)2)

temperature °C underpressurembar

dust content g/m3 1)

scope forutilizationoil, waterORC-processsteamgeneration

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 thematerial to be dried or causes deposits or incrustations in waste heat boiler systems requiring special aidsand expedients for their removal. It is therefore better to dedust the gases first. Although this does cause apressure drop, it is advantagous because the dust is collected and reclaimed, while wear and powerconsumption 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 feasibilityof utilization or energy recovery. The determining quantities are the mass flow rate, the temperature of thewaste 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 [°C] 350 280 1250 250spec, mass flow 1) [m3/kg] 1,5 1,1 0,45 1,4spec, therm, capacity 2) [kJ/m3·K] 1,5 1,4 1,7 1,3heat content 1) [kJ/kg] 740 400 940 420spec, energy output 1) [kWh/t] 206 110 262 116thermal power output [MW] 8,6 4,6 10,9 4,81) 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/dclinker 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 bypassoperation the amount of waste gas discharged to the preheater is reduced. Besides, the temperature of thisgas is lowered. Fig. 2 shows the relation between the heat loss in the preheater waste gas and the proportionof bypass gas diverted from the kiln inlet. In establishing this diagram the proportioning of fuel fired in thecalciner was varied between 50 per cent and 65 per cent. With increasing proportioning of bypass gas theamount of waste gas from the preheater correspondingly decreases and its temperature is lowerd. The twoeffects bring about a more than proportional decrease in the heat loss in the waste gas. The amount andtemperature of the waste gas would similarly be reduced if part of the intermediate gas from the preheater isremoved from the process.

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2.1BYPASS 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 lossesthat this involves are of the order of magnitude of the waste gas heat losses downstream of the preheater orindeed may, if the kiln gases are completely bypassed, exceed those losses. Taking account also of the hightemperature of the kiln exit gas, i.e. the high-grade heat content, it is evident that the greatest possibilities forheat recovery are offered by the hot kiln exit gases. For a plant with a clinker production of 1000 t/d and100 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 coaldrying because this would cause the undesirable substances removed with the bypass gas to be returned tothe 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 withouthaving to dedust it. This method has been applied in a Austrian and also in a German cement plant since1985.

Gas bypassing from the inlet of the kiln may also be applied if the raw material moisture content is sohigh that the heat content of the preheater waste gas and that of the exhaust air from the clinker coolertogether 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 gof dust per m3. This dust, and the gaseous atmosphere itself, usually contain considerable amounts ofsulphur and chlorine compounds which condense on cooling and are liable to form adhering deposits on

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

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relatively cool wall surfaces. This gives rise to the rapid growth of hard coating which are difficult toremove. For this reason it should be checked whether the gas at 1250 °C can suitably be supplied to a heatrecovery installation or whether it should first be cooled—by mixing with fresh air or with other gases or bywater 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 adevelopment 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 maximumrecoverable energy.

However these tests can only give reliable results if they can be achieved in a boiler which is actuallyconnected to a cement kiln. This will rise high costs which can not only be borne by a research anddevelopment 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 isdue to the location of all the plants with a high bypass rate, i.e. Egypt or Iraq, where the fuel costs are so lowthat 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 majorconsideration in the design of such equipment is the possibility of proper cleaning, e.g. with pneumaticrapping devices, and the removal of dust and dislodged coating. It is to be noted that in a two-pass boiler thedusts from the two passes are different and can be separately removed.

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

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT 57

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In this arrangement, the bypass gas could be utilized in the boiler down to 200 °C. Or it is utilized in theboiler only down to 350 °C and can then be further utilized for material drying. The boiler volume wouldthus be substantially reduced and it might, under certain circumstances, be possible to do without gasdedusting.

Another possibility for using the heat of the bypass gases is the aplication of Ahlströms Fluxflowtechnology (11). Fluxflow represents a system where the bypass gases are quenched in a circulating fluid-bed for combined heat recovery and gas cleaning. The heat is recovered as hot water or steam by indirectheat exchange. Due to the quenching of incoming gases in the circulating fluid bed the vaporized alkaliscondensate on the surface of the fluid bed material. Even submicron alkali fumes are largely avoided. So theremoval of alkali components and dust can be achieved in excess of 90 % with cyclones only. Theprecleaned bypass gas has a temperature of about 200 °C, has a much smaller gas volume compared to anair cooled bypass and can be dedusted in the electric pre-cipitator of the cement kiln. As fluid bed materialthe 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 andturned out to be economical, as the hot water can be supplied to the district heating network.

2.2WASTE GAS FROM PREHEATER

The waste gas discharged from the kiln preheater likewise contains substantial amounts of heat. The outputfor 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 itschemical composition—to form coatings or deposits on hot surfaces. A boiler of this kind must therefore beequipped with effective cleaning devices.

If the raw material moisture content is low, so that only a limited proportion of the exit gas is needed fordrying, a waste heat boiler may be installed which utilizes the upper temperature range of the waste gas from400 °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 couldbe additionally installed for electric power generation.

Conventional waste heat boilers for steam operating in combination with a steam turbine and electricgenerator have already been installed as an integral feature in the waste gas duct directly downstream of apreheater in a number of plants (4, 5, 9, 10). In the first case in Switzerland 1981, a 1 MW (el) single-pressureboiler of vertical type was installed on top of a 4-stage preheater (Fig. 4 and 5), producing steam at 7 barand 290 °C and causing a pressure drop of 800 mm w.g. This waste heat boiler is controlled from the cementplant’s central control room. Operation of the boiler has so far never caused interruption or reduction in cementoutput from the plant. Conversely, cement kiln shutdown involves shutting down the whole heat recoverysystem, but the latter can subsequently be restarted quite simply by pushbutton control. The electricalefficiency of the system is 17.8 percent, and specific net electricity generation amounts to 10.8 kWh/t ofclinker.

A pneumatically operated acoustic cleaning system (140 dBA, 200–300 Hz) for the boiler heatingsurfaces has been installed. It can, however, only cope with major fouling of these surfaces. A certainamount 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 withpreheater (Fig. 6) with a clinker production of 7500 t/d. In this case a 7 MW (el) single-pressure boiler of

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vertical type was chosen. The boiler was installed besides the preheater tower. It is a forced circulation typeproducing 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 preheatercan still be used. A modern automatic control system provides fully automated operation. The inlet gastemperature 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 equippedwith waste heat boilers and electricity generating systems, and another four such installations are inoperation 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 Japanesegovernment in terms of tax and in most cases considerably high preheater waste gas temperatures oradditional firing devices for direct steam superheating.

2.3EXHAUST 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 therange of 150–400 °C must be expected. Also, the dust loading of the air may vary greatly, depending on thegranulemetric characteristics of the clinker. For special utilization purposes the exhaust air can be extractedfrom the cooler at two different points and thus be divided into a colder and a hotter portion. The hotterportion is thereby thermally upgraded; its temperature is about 250–350 °C.

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

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT 59

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In former years the exhaust air from clinker coolers was occasionally used for heating water or heattransfer oil (thermal oil) or for drying purposes. The experience gained with such utilization shows that hardlyany wear due to clinker dust occurs in heat exchanger equipment receiving the exhaust air (7) . The thermaleffectiveness can therefore be safely increased without first dedusting the heat transfer medium. This offersthe added advantage that the dust collector installed downstream of the heat exchanger has to handle asmaller 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 usedfor steam raising. The temperature range from 250 °C to 150 °C could be utilized for this purpose, followedby a second stage of utilization incorporating on ORC process in which the air temperatur is further loweredto 70 °C. This low temperature is attainable with exhaust air because it is still sufficiently far above the dew-point. With a 1000 t/d cement kiln it would, with this process, be possible to obtain about 0.6 MW (el) inthe 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 inseveral 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 cementplant which is operating one cement kiln with a clincer capacity of 5000 t/d and one with 4000 t/d. Theturbine 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

Fig. 5.: Heat recovery system

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– waste heat can be effectively recovered from middle and low temperature heat sources as cement kilnpreheater gases and grate cooler exhaust gases.

– the waste heat recovery systems are operating reliable with steam boilers and a turbine for powergeneration.

– 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 isstable and if there is a possibility to part time feed back a surplus of electric power into the public powerdistributing system.

KHD Humboldt Wedag has worked out intensively the feasibility of many projects with different wasteheat recovery systems, and we are in the position together with accepted boiler manufacturers to meet thenecessities of the cement producers.

Fig. 6: Heat recovery system for preheater waste gas

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REFERENCES

(1) Steinbiß, E.: Wege zur optimalen Nutzung der Abgaswärme im Zementofenanlagen mit Zyklonvorwärmer, ZKG39, 1986, H.2, S. 75–79.

(2) Pat.-Anm. KHD AG et al, (Steinmüller) Europa Pat. -Anm. Nr. 84113750, 09. Feb. 1985.(3) Mohrenstecher, H.: Nutzung des Wärmepotentials von Teilgasabzügen an Zementdrehrohrofen, VDZ-Kongreß,

Düsseldorf, Sept. 1985.(4) Lang, Th. A. und Mosimann, P.: Energierückgewinnung in einem Zementwerk, TIZ-Fachberichte, Vol. 107, Nr.

11, 1983, S.816–821.

62 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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(5) 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 Nutzungvon Sekundärenergie, Silikattechnik 35 (1984) H.12, S.355–357.

(8) Gardeik, O. und Schwertmann, T.: Rückgewinnung der Abgasenergie beim Prozezß zum Brennen vonZementklinker, 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.

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DISTRICT HEATING BASED ON WASTE HEAT FROMCLINKER COOLER

Ahlkvist BoWorks Director

Cementa ABS-620 30 SLITE

From its Slite works, Cementa AB has been supplying a district heating scheme for a neighbouring villagesince 1984, generating annual heat sales of some 15 GWh from the waste heat of its No 8 kiln, a 1.4 mtacapacity line, utilising waste heat from the grate cooler. Total investment costs to develop this system areput at US$ 2.0 million and by 1990 the net profit of the project are Forecast at about US$ 0.5 million perannum.

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 demandof heat makes district heating an economic alternative.

The distribution system consists of standard preinsulated heat pipes and there is a heat exchanger in eachbuilding connected to the district heating system.

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All costs were covered by the project, so the customers did not have to pay anything to convert theirsystems 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 plants2 Households3 Other industries, municipal services, stores etc4 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 grateclinker cooler. Hot kiln gases are used to simultaneously dry the raw materials in a vertical roller mill with acapacity of 400 tonnes/hour.

The clinker cooler has three grates and is equipped with a hammer crusher between the 2nd and 3rdgrate. Hot air is taken out just at the beginning of the 2nd grate and is used to dry coal in a roller mill with acapacity of 30 tonnes/hour. At the end of the 2nd and 3rd grate exhaust gases are taken out and cleaned in agravel bed filter.

Exhaust gas from the clinker cooler turned out to be the best energy producer from the pollution andtemperature point of view.

By using these fairly clean, dry and hot gases, we were able to build a simple heat exchanger withstandard components. The gases, with an average temperature of 230°C, are taken out after the gravel bedfilter into a by-pass loop. By controlling the speed of the fans the water temperature is held at a desiredlevel.

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 coupleof 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 heatingsystem 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 beenpayed 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 balanceof 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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The annual need of waste heat for district heating is related to the climate. Thus the need is higher duringthe winter period. Fig. No. 4.

A problem is that the cement demand normally falls in the same period, so we stop the kilns formaintenance. Therefor it would be better to combine district heating with the generation of electrical powerusing process heat.

As only a minor part of the high temperature waste energy is required for district heating, there is aninvestigation going on aiming to use waste heat for electricity production in an “Organic Rankine Cycle”process. This process uses organic fluid instead of steam.

Fig. 1.

Fig. 2.

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This would cost us another US 2.0 million and produce about 7 GWh of electricity annually. So far theeconomy in such a project is somewhat uncertain with today’s prices on electrical energy. However, anelectrical 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.

Fig. 3.

Fig. 4.

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Fig. 5.

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HEAT RECOVERY ON THE SMOKE OF THE CEMENTKILN AND UTILIZATION OF THE RECOVERED ENERGY

Jean-François BOUQUELLEDépartement 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 inliquid 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. Forall cold water temperatures above 40 deg.C, the hot water temperature remains fairly stable atabout 72 deg.C. Weth a smoke temperature between 120 and 150 deg.C and a water content ofabout 0.3 kg water vapour per kg dry gas, such an exchanger one cubic meter in size, is able towarm up 40 m3/h of water from 40 deg.C to 72 deg.C. This type of heat recovery is bestapplicable to the heating of buldings or workshop.

As long as proper care is taken to neutralize the acidity of the circulating water, the operationof the heat recovery is troublefree.

At CIMENTS D’OBOURG we are running two 3 000 tons per day wet process cement kilns. After theelectrostatic 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 kJper kg dry gas) is six times higher than sensible heat. To recover this heat we need an exchanger which willcondense the water vapour without getting clogged by hydrated kiln dust.Such an exchanger exists. It was invented around 1965 by Professor LEFEBVRE of the FacultéPolytechnique 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

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on it so that this water flows down in liquid sheaths around the small cables. Dust from the smoke doesn’tcome 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 8mm, we can tighten 16 km of cable in a volume of 1 cu. meter. The specific contact area is higher than 100sq. 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 gasthrough-flow with a low pressure drop.

This heat recovery exchanger is thus very performing and perfectly suited to the recovery of heat fromthe 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 thensprayed 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 coldwater temperature fluctuates between 40 and 60 deg.C, the hot water temperature varies only between 71and 74 deg.C. This is because we are condensing more or less of the water vapour from the smoke andrecovering 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 120deg.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 afterthe electrostatic precipitator. The second precaution was to stop also when the return temperature of thesecondary circuit gets above 60 deg.C.

Normally, the exchanger is condensing the water vapour. 1.200 litres an hour is an average figure for thecondensed water. This condensed water escapes the primary circuit by the overflow-pipe of the collectiontank. Doing so it is removing enough dust to keep the solids concentration in the primary circuit below 0.2 gper litre.

It may happen that if the primary circuit water is not cooled enough—for instance in summer when thebuildings do not require heating—the exchanger is not condensing any more but instead evaporating. If thisis 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 canbring its pH down to 3.5. Usual stainless steel cannot stand such a low pH; we have to neutralise thecirculating water. We installed therefore a caustic soda dosing pump with a regulation loop. After a fewaccidents we had to an place electrical relay shutting down the installation for a pH below 5. Average NaOHusage is 80 mg pure NaOH per standard cubic meter of smoke.

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Secondary circuit

But for the strict limitation of the hot water temperature to 69 à 72 deg.C, the secondary network is similarto a normal heating network. This temperature is the temperature of the primary circuit minus the 2 deg.Ctemperature differential across the uncoupling plate heat exchanger.

Taking this restraint into account, we decided for a parallel-series network. The existing warm watercentral heating systems of the workshop cloakroom and offices and of the administrative buildings are fedin parallel by the network warm branch. The other buildings, stores and workshop hall had gasoil fired warmair generators. So they couldn’t be converted, we had to install completely new water to air heatexchangers. We dimensionned them specially to be able to feed them from the colder return branch. In thisway, the water we send back to the Amazone exchanger is colder than it could be coming out directly fromthe 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 ofthe main secondary circuit starts also. When the primary circuit stops, this pump will keep running until thetemperature at the outlet of the uncoupling plate heat exchanger drops below 50 deg.C. A flow metercontrols 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 heatgenerator. Each user is checking the temperature of the network at the point where it is tapped off. Above aset temperature, it connects with the recovery system and switches off its generator. With dropping networktemperature 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 isreached in the main secondary circuit. The administrative buldings will connect themselves to the recoverysystem 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 andin the adninistrative buildings was 90 deg.C. We calculated that, because of the 70 deg.C. temperature limitof the recovery system, these users must go over to boiler heating for an outside temperature belowminimum 7 deg.C; only the users placed on the return branch can still be fed. It is a bit of pity that we hadno occasion to check if this calculated figure is real. Nevertheless, from what we have been able to observewe 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; thisis 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 yearsbefore, 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 someexperimentation on the system by the assistants of Professor LEFEBVRE the cost of a new investment shouldbe somewhat lower than ours. It wouldn’t exceed 15 millions BEF or 750.000 DEM. The pay-back period isthus somewhere between 3.5 and 10 years depending on the price of gasoil.

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

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

‘Amazone’ module

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UTILIZATION OF WASTE HEAT FROM THE CEMENTROTARY KILN

K.-H.WEINERTInteratom GmbH

Friedrich-Ebert-Straße5060 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 radiationabsorber (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 rationalutilization of the energy applied, in particular in the case of manufacturing processes requiring a lot ofenergy are released unused to the environment, whereby losses of approximately 10 %, related to theapplied 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 whichcomplicates the design of an absorber for the waste heat of the shell. On the one hand the averageguaranteed power must be attained, on the other hand, however, the size of the absorber is not to beincreased unnecessarily. The increase of the shell temperature which is caused by the erection of theabsorber 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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– lenght 6 m– Kiln shell temperature (without absorber) 290 °C– power max 650 kW– power guarantee 400 kW– absorber temp. 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 theyare painted with black absorber varnish and are equipped with weatherproof thermal insulation on the rearside.

The absorber plates are mounted on two hinged steel constructions in such a way that they form twoheptagonal half-sehlls (Fig. 2). During normal operation these completely enclose the kiln over a length of 6m with a wall distance of approx. 0.5 m.

4.Operating systems

The complete facility consists of 3 closed circuits or loops

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

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– 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 heatexchanger 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 drainedduring winter shutdown of the kiln. The supply temperature is 80 °C, the discharge temperature 100 °C. Ifless 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 placedapprox 20 cm from the surface of the kiln. The temperature display with limit value indication can bechecked 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 safetyposition. 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 havebeen reached.

Fig. 2 Principal Arrangement of the Waste Heat Absorber Plant

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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 theconnected 3 heating circuits of the operating building is effected via three-way reversing valves in therespective return lines of the heating boilers (Fig. 3). In the case of feed temperatures of more than 60 °C inthe supply lines to the buildings, the intermediate heat exchanger is connected in series with the heatingboilers and the supply of heat is normally provided 100 % by the absorber. The heating boilers are onlyswitched on if the absorber power is no longer adequate. The intermediate heat exchanger is bypassed attemperatures of less than 60 °C.

Cooling circuit

The cooling circuit is used for adaptation to the heat requirement of the consumers. The absorber powerexceeding the requirement ist discharged via a cooler cooled with well water. In addition, the cooling circuitacts as emergency cooling in the event of failure of the heating circuit and is therefore designed forremoveal of the total absorber power.

5.DATA ACQUISITION SYSTEM

Adequate measuring instruments and a data acquisition system were installed to determine all relevanttemperatures 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. ThisFig. 4 shows the absorbed power as a function of absorber inlet temperature and kiln shell temperature. Fora kiln shell temperature of 340 °C (which corresponds to theoretical layout temperature of 290 °C withoutabsorber) a power of approximately 600 kW was expected, but a power of only 480 kW was achieved. Thedifference can be explained by the convection losses caused by a large natural convection flow through thelower and upper gap of the absorber.

These convection losses were estimated at approx. 220 kW, the half of which could certainly be used bythe installation of the top and bottom cover sheets as it was planned in a second part of the measuringphase. Therefore it can be stated that the expected power of approx. 600 kW could be achieved with a wellfunctioning bottom and top cover sheet.

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7.PROJECT REALIZATION

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

78 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Fig.

3 O

pera

ting

syst

ems

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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 commissioningphase to adjust the components to the specified requirements. For examination of the influence of variousconstructive elements on the convective losses only the cover sheets at the sides of the absorber weremounted. 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 Content Forecast Costs in DM Real Costs in DMI Planing 62,324,−

– Optimization

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

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Phase Content Forecast Costs in DM Real Costs in DM– Detailed design– Specification

II Carrying out 591,176,– 906,256,–– Award– Supervision of construction– Commissioning

III Measuring Program 100,000,– 74,205,–– Data acquisition– Technical-Economical Evaluation– DocumentationTotal 753,500,– 980,461,–

The forecaste costs have been exceeded by than 20 %, especially caused by the steel structure, a redundantpower supply and more extensive engineering work. Taking the real costs fo the project and theinfrastructure of the Bonner Zementwerke as a basis it can be stated that the costs for future plants will notdrop below approx. 600,000,– DM.

The technique of steel structure, absorber plates and heat transfer loops is conventional and cannot bereduced for future plants.

Rotary kiln waste heat absorber plants with its high investment costs are only able to compete withconventional industrial systems if the degree of exploitation could be increased from the actual value ofapprox. 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 ofapprox. 600 kW (with top and bottom cover sheets installed) exceeds the installed power of 540 kW of theconventional heating system of the Bonner Zementwerke AG.

For bigger follow-up plants investment costs for the complete system of approx. 900,– DM per kWeffective power are estimated. Thus, at a high annual rate of utilization, the system definitely achieves theamortization period required today for energy-saving investments. The utilization of radiation waste heatfor 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 ProductionRotary Kiln for Heating and Domestic Water Supply of Buildings

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ENERGY SAVING BY UTILISATION OF HIGHEFFICIENCY CLASSIFIER FOR GRINDING AND

COOLING OF CEMENT ON TWO MILLS AT CASTLECEMENT (RIBBLESDALE) LIMITED, CLITHEROE,

LANCASHIRE, UKPETER FREDERICK PARKES

Milling Department ManagerCastle 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. Thecement 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 mills-6 at 600 kW2 at 2 000 kW2 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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We decided to install a high efficiency separator. The principal reason for selecting this option was that itgave us the required extra quantity of cement with the lowest capital investment. The lower finished cementtemperature 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 cementfrom the separator is collected in a Redecam dust collector rated at 110000 m3/hour. The cement from theRedecam bag filter is then transported to the silos using the existing belt and elevator transport system (seeFigure 2).

The coarse tailings from the separator are returned to the mills via air slides. The second of these airslides is equipped with a proportioning valve, that splits the tailings equally between two weigh belts. Theweight signals from these belts are used to determine the position of the proportioning valve, so as todeliver equal amounts of tailings to each mill. This signal is also used in a loop controller with the clinkerand 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 werealso increased. Mill 9 Chamber I effective length 3.7 m with 29 tonne of grinding media ø 60 to ø 90. Chamber

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

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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 ofgrinding media ø 15 to ø 20.

In order to improve the air flow through the mills Bazzi inlets replaced the original F L Smidth scoopingdevices. Bazzi outlet grates were also employed, but the original F L Smidth combidan diaphragms wereretained.

INSTALLATION—INTERFERENCE WITH PRODUCTION

The conversion was carried out from the end of December 1988 into January 1989, as there is always a dropin cement demand at that time of year.

The mills were shut down on 22nd December and re-commissioned on open circuit at the beginning ofFebruary. The total down time was 40 days, during which time the following work was carried out:

1. Installation of new mill inlet chutes.2. Re-positioning of the diaphragm in Mill 10.3. Installation of new outlet screws and air slides.4. Installation of a new bucket elevator.

Trials on closed circuit grinding commenced on 8th February. The system was fully commissioned andrunning continually on closed circuit by 10th March. This included changeover to a new control desk andmicroprocessor control system, which had to be fully checked out and proven, before we could allow nighttime 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.

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

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At the final performance trials a maximum of 66 tph was attained, but this eventually settled down to 60tph 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 inclinker grindability is also a significant factor, as other mill throughputs were low in November andDecember, 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 precedingthe shut down, so consequently performed better on re-starting following repairs during re-commissioningon closed circuit.

Though it is extremely difficult to quantify the improvement directly attributable to the installation of theclassifier itself, in view of the other influencing factors mentioned above, we are certain that at least 25% ofthe 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 andparticle 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 consumptionwas 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.

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

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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 anincrease of around 40%, of which at least 25% is directly attributable to the classifier, this has been thegreatest benefit.

2.Improved Strengths

The 28 day strength of the cement produced on the high efficiency separator has shown an improvement ofover 6% against open circuit produced cement, i.e. an average of a series of tests showed strengths of 48.3N/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 toabout 75/80 °C. This is due to the cooling effect of the separator, with ambient air as well as air from themill ventilation.

4.Improved Energy Consumption

An average improvement of up to 6 kWh/tonne has been found on the closed circuit system; animprovement of 13%. This saving in power consumption has been achieved at the same time as increasingproduction, improving cement strengths and reducing cement temperatures, as stated above.

TABLE 1. Comparison open to closed circuit

Open Closed Change

Tonnes per hour @ 3600 Blaine 42 tph 60 tph + 43%Energy consumption 45.29 kWh/t 39.25 kWh/t (at 60 tph) −13%28 day strengths (100 mm concrete cubes to BS 4550) 45.3 N/mm2 48.3 N/mm2 +6%Cement temperature 120°C 80 °C −40 °C

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DISCUSSION

TO: MR STEINBISSDR TOM LOWES, Blue Circle Cement

QUESTIONDoes the 3000 tonne/day you mentioned as a minimum size capacity plant for the installation ofwaste recovery for electricity generation, include waste heat recovery from both the cooler and thepre-heater exchanger? If it did, what price/kWh would you expect for break-even investment?ANSWERYes, it included the waste heat from both the preheater and the cooler. The break-even pricecannot be given. You cannot give a general figure because of the assumptions which would haveto be made.

CANCELA DE ABREU, Secretary of State for Energy, Portugal

QUESTIONWhat type of fluid would you propose using in the ORC System—DR114 or a different one?ANSWERDifferent fluids are suitable for different applications. An American company uses hydrocarbonsas a fluid, for example methane, used as a fluid.

R K GUPTA, J K Cement Works, India

QUESTIONIn your case study you mention a 1000 tonne/day plant, but in your conclusion you state that thesystem is only suited to plants with 3000 tonne/day capacity. Could you clarify whether this isfrom the technological point of view or investment criteria?

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ANSWERThe figures have been standardised at 1000 tonne/day to allow for ease of multiplication. It is notintended to give the impression that ‘it is feasible to equip a 1000 tonne/day kiln’.

MR F AELLEN, Holderbank, Switzerland

QUESTIONWhy is there no breakthrough in the use of the Organic Rankin Cycle?ANSWERThis has been considered for many plants but there are no satisfactory reference plants in thecement industry. The ORC is operated satisfactorily in other industries and will eventually beapplied 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 areforming plant in the Portuguese chemical industry.

MR H TAKAKUSAKI, NCC, Japan

QUESTIONWhat are the advantages of organic fluids over water? One disadvantage is if the fluid leaks intothe furnace gases, which could be dangerous.ANSWERThe fluid is not actually dangerous. You need another fluid to go on the ORC which will operateat lower temperatures than water will. If you use an organic fluid you can still be efficient even atlower temperatures.

TO: MR AHLKVIST—No questions.TO: MR BOUQUELLEMR SIRCHIS, regarding payback being dependent on fuel oil costs.

QUESTIONWhat is the cost of the fuel given by the two units in the payback period?ANSWERThe low cost 650 GCal/Belgian Franc=6 BEF/litre gas oil, the high cost 17 BEF/litre gas oil. Thepresent price in Belgium of 8 BEF/litre (0.2 ECU/litre) gives a payback of between eight and nineyears.

MR NOHLMANS, Novem, Netherlands, Agency for Energy

QUESTIONHave you done any pollution measurements on this type of equipment?ANSWERThe smoke from the kiln is 60% cleaner than otherwise. The water is polluted which requiresadditional treatment. The heat exchanger is used elsewhere as a reactor for retaining sulphur fromfumes in a plant making coke from coal.

MR AELLEN, Holderbank

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QUESTIONRegarding the layout of the heat exchanger, the two fluids are in direct contact. If you had abigger system, how would you lay out your heat exchanger? Would you just extrapolate or wouldyou calculate?ANSWERThis is a question for the designers of the heat exchanger. For bigger machines you can alter theconfiguration in many ways.

MR PER KNUDSEN, Gotlands Energiverk AB, Sweden

QUESTIONHow far away is the town of Mons from the cement plant?ANSWERAbout 4 km.

MR PECH, Vicat Tour Can, France

QUESTIONDo you know if you can use it as a de-sulphurising unit?ANSWERTechnically it is possible, but whether it is economic is unknown.

PROFESSOR MARIO NINA, University of Lisbon, Portugal

QUESTIONDid you have any fouling problems with your plate heat exchanger?ANSWERThe dust content is around 0.2 g/litre of water. The heat exchanger is of 4 pass configurationdesigned with removable bottom plates to enable it to be cleaned.

TO: MR WEINERTDR TOM LOWES, Blue Circle Cement

QUESTIONWas there any detriment to the refractory or shell life?ANSWERThe shell temperature has increased by between 30 and 50°C. Unfortunately the plant closed aftersix months for economic reasons. The plant was dismantled and taken to Turkey and there was noapparant damage to either the shell or the refractory.

TO: MR P F PARKESDAVID HARGREAVES, Editor, International Cement Review

QUESTIONSHow much did it cost?What was the payback period?What are the disadvantages?If you did it again, would you do it differently?ANSWERS

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

DISCUSSION 89

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“HOLDERBANK’S” ENERGY MANAGEMENT IN THE1990S

M.BLANCK“Holderbank” Management & Consulting Ltd,

CH-5113 Holderbank/Switzerland

SUMMARYElectrical 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 throughbetter 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 availableto enable people to monitor and control the use of electrical energy. To meet this industry-wideneed “Holderbank” Management & Consulting Ltd. has developed a number of tools andorganizational procedures to upgrade the quality of energy management.

1.INTRODUCTION

Increasing electricity rates in many countries and very complicated tariff structures make further energycost reduction difficult. However modern information technology offers new opportunities to improve thequality 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 leastthe 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 theuse of electricity itself.”

We are convinced that this statement: “…there remain opportunities for improved efficiency in the use ofelectricity itself” is also very true for the cement industry. For us, using these opportunities meansdeveloping 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 andactivities 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 contractthe most efficient way. Energy logistics considers both power supply from the utility as well as self-generated 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 powergeneration. 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 managementcontrolled by the utility or by the consumer. Yearly review of the contract regarding cement market demandand 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 andconsumption 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, costsavings 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 specificenergy 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 introductionof 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, rollerpresses etc.

Operation Optimization

Energy efficiency is always dependent on the operating conditions of plant equipment. The objective is tobring and keep operation on an optimal level.

For this purpose, all relevant process and machine parameters have to be continuously monitored. Whilemost of the required process parameters are available and recorded. These days there is a general lack ofenergy 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 inadvance.

On the other hand, expected savings from improved operation can normally not be assessed in advancebecause of lack of suitable energy data. Therefore, the achievable savings are in general unknown and canonly 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 thetime utility pricing practices like time-of-use tariffs and demand charges came into effect, correspondingmeasures were consequently developed and introduced on the consumer’s side—like increasing the lowtariff 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

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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 gapsare:

– 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 sharperenvironmental 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 andexperiences.

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, theawareness of how to deal with energy, especially electricity, is not yet far enough developed in modern plantoperation.

Of course, there are already many information systems implemented. But energy information systems andrelated energy management functions within the daily operating routine hardly exist.

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Many plant people, especially those on lower hierarchical levels, do not feel really concerned aboutenergy conservation. The reason why is obvious. They do not have much or even any useful energy relatedinformation 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 ofa lack of suitable information. Because of this situation, there is generally not enough incentive ormotivation 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 ofTechnology are now preparing a research and development project named “Energy InformationManagement in Industrial Plants”.

Objectives

The purpose of the project is to research and develop information methods and means for rational electricityuse. In particular, in this project we have to answer the question: How can energy management be integratedinto the management structure on both corporate and plant levels?

Furthermore, within the management structures, the following question has to be clarified: What is thenecessary responsibility structure and the required range of competence of plant people that can largelyinfluence energy consumption?

The new concepts and information tools which have to be developed shall lead to substantially enhancedenergy 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 energymanagement system implementation projects. Besides better energy logistics, these projects have also thegoal 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 inmany cement plants, electrical energy data is still monitored “by hand” in practically all plants: normallyonce a month. In many cases, the energy figures obtained cannot even be clearly assigned to individualdepartments and groups of machinery. The reason for this is the complicated entanglement of energy inputsand 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 theenergy consumption has to be allocated by estimate. The only purpose served by such conventional powerbookkeeping exercise can be an approximate allocation of the energy consumption and costs to thedepartments. This inaccuracy makes it impossible to identify any existing potential for energy saving. Inother words, the energy consumption figures produced in this way are useless as guide figures within theplant 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 asfollows:

– 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. Engineeringand 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. Theseare the Outao Cement Plant of SECIL /Portugal and the Souselas Cement Plant of CIMPOR/Portugal. Inone factory, we have investigated the data in greater detail for two months jointly with the plantmanagement. It has shown in a first review, during a three day workshop, that there is a remarkable volumeof energy consumption which can be considered as savings potential. The following examples explain theprinciple 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 andthe 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” daysii) 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 April1989 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 areshown. Almost the same quantity of raw meal was produced (namely 7’000 tons a day) during each of thetwo days. But, as a matter of fact, on the 11th of April the raw mill consumed US$835 more energy than onthe 29th of April. (US$835 is based on an average cost of 5 cents per KWh).

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Example: Wasted Energy for idling Equipment

This example highlights those days with no production but a considerable quantity of energy consumptionnevertheless.

Figure 5 shows how much energy is consumed when production is zero. This graph shows the demandprofiles of three of such “zero-production” days. For better comparison, the same power scale as in thegraphs of figure 4 is chosen.

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

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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 savingsopportunities 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 organizationwould be required in order to integrate the energy data and information (which flow day-by-day) into thedaily routine work.

Accordingly, the second goal of the before mentioned workshop was to establish an energy managementstrategy 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 stepsof the team is to put the strategy into practice by improving the energy utilization in the raw and cementmill sections as mentioned before.

This evaluation project was started at the beginning of October 1989. The preparation of a comprehensivereport is planned by May 1990 for the IEEE Cement Conference in Tarpon Springs, Florida, USA. By thenwe 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” energymanagement development programme.

In conclusion, energy data preparation and energy information management imbedded in an energymanagement 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, itseems to be of pressing importance to use the existing energy as efficiently, i.e. rationally, as possible. Inaddition to this, attempts should always be made to reduce the energy costs to a minimum, purely on thegrounds of operational economy. Energy management is hence being continually improved and developedwith the application of the most modern information technology.

BIBLIOGRAPHY AND REFERENCES

(1) OECD/IEA Publication: Electricity End-Use Efficiency. OECD Publications Service Paris, 1989.(2) Blanck, M.: Energy Data Analysis. Zement-Kalk-Gips, Bauverlag Wiesbaden (1989) No.6 pp 288–290.(3) Spreng, D.: Energiesparpotentiale in Industriebetrieben. NFP44, SIASR, St. Gallen, 1986.

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ENGINEERING AND ENERGY SAVINGSJean DUMAS

CITEC, Centre Industriel et Technique des CIMENTS FRANÇAISLes Technodes, 78930 GUERVILLE, FRANCE

SummaryThe 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 ofequipement 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 itslocal adaptation to the material treated, for instance by preliminary drying and crushing of the rawmaterials,

– a second way, is to improve the installation by its reliability and simplification, eliminating weak pointsin 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 havemade to four of our plants in order to improve their productivity and their energy efficiency. These fourplants are at BEAUCAIRE, BEFFES, BUSSAC AND COUVROT.

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2.THE CASE OF BEAUCAIRE

2.1THE 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 intoa 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

2.2MODIFICATIONS

The new burning line has been constructed on the basis of the 1 450 t/d kiln by transforming it into a dryprocess kiln; the increase in capacity has been obtained by setting up a pre-heating tower withprecalcination RSP ONODA with separated air; the pre-heating tower comprises five stages which providefor better utilization of heat of the exhaust gases. Temperature is approximately 320°C at the output fromthe 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 FCBball mill.

These various transformations have been accompanied by modifications concerning the organization ofthe production flow, storage and improvement of the proportioning of the raw materials.

2.3BALANCE SHEET

Independently of the reliability of the equipment, this reliability being linked with the simplification of theproduction 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 thereduction in fixed losses related to one kg of clinker.

On the other hand, the electrical specific consumption of the raw material milling workshop has fallenfrom 30 kWh/t to 20 kWh/t of raw material, and this is due to the good adaptation of the vertical mill to theBEAUCAIRE raw materials.

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BEAUCAIRE PLANT

OBJECTIVES RESULTSSIMPLIFICATION OF FLOWS 1 RAW MATERIAL MILL INSTEAD OF 3

1 KILN INSTEAD OF 3IMPROVEMENT OF ENERGY EFFICIENCY THERMAL GAIN OF 125 KCAL/KG ELECTRICAL

GAIN IN RAW MATERIAL MILLING 30 %ELIMINATION OF FUEL OIL AND GASCAPACITY UNCHANGED CAPACITY MAINTAINED AT 2800 T/D

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3.THE CASE OF BEFFES

3.1THE PLANT IN ITS INITIAL STATE

The conversion of the wet, into semi-dry process installations, goes back some fifteen years for the BEFFESplant. 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 wasequipped with a LEPOL grate and the other was a kiln with a cross shaped internal exchanger. The twocoolers 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.

3.2CONVERSIONS

The objectives of the conversions are very similar to those of BEAUCAIRE. These conversions concern theburning workshop, the cement milling workshop and the raw material mill furnace.

. Handling of raw materialsHandling of raw materials has been simplified which has resulted in the elimination of the old gantry

halls.. Burning workshopA 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 byothers, richer in alumina; the grate plates are now in 30 % chromium steel. The temperature of the grate iscontrolled and triggers an alarm in the case of too high a temperature. The height of the layer has risen from18 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 millwas old and the trunnions of the two FCB and POLYSIUS compound mills were of too small a crosssection. These mills have been replaced by a compound 1700 kW POLYSIUS mill, a mill which operates inopen circuit.

. Raw material mill furnaceIn order to reduce energy costs, the raw material mill furnace has been converted to coal fuel.

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3.3BALANCE SHEET

The current performances are as follows:

– thermal consumption, firstly the recycling of the air cooler represents a gain of 46 Kcal/kg, and secondlythe installation of precalcining provides an increase in production from 1 370 t/d to 1 800 t/d which haspermitted a reduction in the specific consumption of the kiln alone from 800 Kcal/kg to 785 Kcal/kg. Thetotal 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 productionand energy performance has been maintained.

BEFFES PLANT

OBJECTIVES RESULTSSIMLIFICATION OF FLOWS 1 SINGLE KILN INSTEAD OF 2

2 CEMENT MILLS INSTEAD OF 4

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BEFFES PLANT

OBJECTIVES RESULTSIMPROVEMENT IN ENERGY PERFORMANCE THERMAL GAIN OF 50 KCAL/KGELIMINATION OF FUEL OIL AND GASADAPTATION OF CAPACITY CONVERSION OF THE RAW MATERIAL MILL

FURNACE TO COALINCREASEOF THE CAPACITY OF THEBURNING LINE BY 27 %

4.THE CASE OF BUSSAC

4.1THE 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 preparation2 —To increase the production capacity from 1800 t/d to 2640 t/d3 —And to improve the thermal performance

In the BUSSAC quarry, there are two raw materials: lime, or high grade, and clay material, low grade. Thisvery damp and plastic clay material is sticky and raises great problem in handling. In addition, the low silicamodule requires an important addition of sand.

The initial design of the plant had naturally taken account of these factors. The preparation of the rawmaterial 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 wasnot reliable,

– in the kiln and the dry crushing of the raw material, the thermal consumption was relatively high becauseof the temperatures required to dry the raw materials,

– the planetary cooler induced process and mechanical problems (mediocre clinker cooling, fatigue in thefurnace casing).

4.2MODIFICATIONS

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 theautomatic 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 theresults of the automatic ISYS free lime analyser operating continuously. This automatic control system, byregularizing and optimizing the operation of the burning line continuously, improves both the energyperformance and the quality of the clinker.

4.3THE BALANCE SHEET

As regards raw material milling, because of the better suitability of the equipment to the materials, theelectrical consumption of the workshop has fallen from 41 kWh/t to 34 kWh/t of raw material and inaddition, 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 isessentially due to the recycling of air in the cooler to dry the raw material. Output has increased from 1570t/d to 2400 t/d and in addition, the utilization rate of the furnace has increased by 25% (relative value).

BUSSAC PLANT

OBJECTIVES RESULTSIMPROVEMENT IN PREPARATION OF RAWMATERIAL

ADAPTATION OF THE WORKSHOP– STOCK BELT–AEROFALL

INCREASE IN CAPACITY PRODUCTION CAPACITY RAISED FROM 1500T/D TO 2400 T/D

IMPROVEMENT IN ENERGY PERFORMANCE ELECTRICAL GAIN IN RAW MATERIALMILLING=25 %

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BUSSAC PLANT

OBJECTIVES RESULTSTHERMAL 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 thekiln part since they consist of:

1 —replacement of the planetary cooler by a grate cooler with electrofilter2 —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 theproblems 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 a108 m2 grate surface area. Secondly, the internal diameter of the body has been reduced from 5.6 m to 5 min the burning zone. The DOPOL tower has been modified to insert a calcination chamber betweenturbulence 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 specificconsumption 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 (andincreasing the capacity).

COUVROT PLANT

OBJECTIVES RESULTSINCREASE RELIABILITY OF EQUIPMENT REPLACEMENT OF PLANETARY COOLER BY

GRATE COOLERREDUCTION IN ENERGY CONSUMPTION SPECIFIC CONSUMPTION REDUCED BY 60 KCAL/

KGINCREASE IN PRODUCTION CAPACITY PRODUCTION INCREASED FROM 3800 T/D TO

4200 T/D

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ENERGY SAVINGS IN CEMENT KILN SYSTEMSERIK BIRCH

F.L.Smidth & Co. A/S77, Vigerslev AlléDK-2500 Valby

Denmark

SummaryIn 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 systemstherefore assume a greater importance.

The paper outlines some of the methods available for optimizing existing kiln systems, withparticular 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 anew kiln or an existing one. Furthermore, for the choice of method and its profitability it is important toensure that the increased production can be sold. Before selecting a certain method, the circumstances of theprocess 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, theirinherent humidity, transport facilities etc. Studies of the market in order to establish expected salespossibilities should be made before selecting the right process. Although this is a major and importantsubject it will not be treated further in this article, which will focus on the most profitable energy savings inexisting plants.

2.DEFINITION OF PRODUCTION TARGETS

The market, relations to possible competitors, available reserves in the quarry, the infrastructure, economicaland political factors as well the price of cement, fuel and electrical energy must be evaluated carefully, anda production target should then be formulated.

Generally, it can be said that energy savings alone seldom pay the investments herein, unless taxreductions 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 thetechnical 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 instancein the form of a work sheet on a computer. The entries should be reasonably detailed and expressed as afunction of a mass and energy balance.

For instance, the energy price can be split into contributions from all the departments of the plant, such asthe crushing, raw mill, coal mill, kiln, cooler, and cement mill departments. The global effect of amodification 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 beknown. The best tool for this is to prepare a mass and heat balance and then simulate the process with a viewto identifying possible savings.

The following considerations apply to the kiln department in particular, but some of the techniques arealso applicable to other departments.

The preparation af a heat balance takes as a starting point the measurement of the output by weighing ofthe feed or product, whichever can be carried out in the most exact way. Weighing of clinker is normallypreferred. The input of fuel should also be weighed during the test period. For calculation of the radiationand 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 inand outgoing flows must be measured, in particular clinker, smoke gas out of the kiln, excess air, air, rawmeal and fuel.

Samples of raw meal, clinker, dust, fuel and smoke gas out of the kiln should be taken for analysispurposes.

Pressures (and underpressures) in the process should also be measured with a view to estimating thepossibilities 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 fourstage 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 semi-indirect coal mill systems, reduction of reaction heat, improvement of the cooler efficiency, additionalcyclone stages, improvement of the cyclone efficiency and reduction of possible smoke gas losses due toinjection 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 NORMALindicates the normal values and the column marked HIGH shows values corresponding to a highly insulatedkiln system.

The indicated radiation losses are 160 kcal/kg clinker for a normal IL-E-system and 123 kcal/kg clinkerfor 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 ratherclose 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 andcalcinator.

By the installation of a highly insulating lining in a preheater, a surface loss of approx. 600 kcal/m2/h cantypically be obtained, corresponding to a 50 per cent reduction of the surface loss in relation to olderpreheaters with a poorer insulation.

If an insulating lining is installed in the rotary kiln and the planetary cooler, 10–20 kcal/kg clinker cantypically 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 quantityof 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 maybe 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/kgclinker is found as false air, an additional heat consumption of about 11 kcal/kg clinker is required, as thenormal 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 requiredenergy for heating of the false air to the outlet temperature plus a somewhat larger smoke heat loss due to thelarger 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 thesame 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 kilnand/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 orvelocity may cause coal to fall out of the flame. Too coarse coal meal (or too cold oil) may also result in COformation. The cause must be found in each case before a solution can be given. A modern burner type withseparate 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 poorlyatomized), a too short gas retention time, uneven temperature profile in the calcinator or a too lowcombustion 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 energyconsumption 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 byrelatively cold and humid air from the coal mill. The additional cost for the air will be almost as mentionedabove for the kiln hood, but due to the high heat capacity of water vapour, the smoke loss increasesconsiderably.

The air quantity will typically be approx. 20–25% of air. (the required air quantity for combustion withoutexcess.air), corresponding to approx. 0.22–0.28 kg/kg clinker. The normal quantity by indirect firing will beapprox. 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 heatconsumption 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 24–33kcal/kg clinker. Besides, a better stability is generally obtained by indirect firing, as the kiln is isolated fromthe effect of the start and stop of the mill. It is difficult to calculate beforehand the saving from a greaterstability, but it is estimated to vary between 5–25 kcal/kg clinker, dependent on the fluctuations in coalquantity for the direct firing. See Appendix 2, table 4 for a comparison of two typical systems, andAppendix 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 recarbonatizeand liberate heat.

A reduction of the 4th stage efficiency from 85% to 75% will typically result in a 9–12 kcal/kg clinkerhigher heat consumption.

The increased recarbonatization may also cause the 3rd stage temperature to enter into an area where therisk of cyclone blockings increases.

On the other hand, the effect of a deterioration of the efficiency of the top cyclone is not so important forthe heat consumption of the kiln system. A reduction from 92% to 82% efficiency for stage 1 (theuppermost) gives an increase in heat consumption of approx. 3–4 kcal/kg clinker, which is of lessimportance in this connection. (It will, however, have an influence on the dimensioning of filter, dusttransport 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 thisstage is often lower than for the other stages. The installation of a triangular constriction may contribute to abetter efficiency. In difficult cases special central pipes of ceramic material or special heat resistant steelmay be recommended. To ensure durability of this central pipe it is often made as rings, each one suspendedon 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 ofthe heat in clinker, excess air and surface loss. The normal values are 130 kcal/kg clinker for a grate coolerand 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 heatconsumption, the air consumption from the cooler increases, and the loss decreases. At lower heatconsumptions the cooler heat loss rises, as a smaller part of the recuperated heat is utilized in the kilnsystem.

By optimizing the cooler operation, 10–20 kcal/kg clinker can often be saved, dependent on the actualcondition of the cooler. It will lead too far to enter into details here, but a couple of methods may bementioned.

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 wallsunder 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 theefficiency 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. 16–20kcal/kg clinker can be obtained by the installation of a 5th stage. This corresponds to a 35–45°C drop in theoutlet temperature. With a modern, highly efficient low pressure cyclone the pressure drop will be anadditional 50 mm VS (corresponding to approx. 0.5–0.6 kWh t of increased power consumption in thesmoke gas fan).

A 6th stage will save approx. 8–10 kcal/kg clinker and costs approx. 0.5–0.6 kWh/t more in powerconsumption. 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 energyconsumption 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, thekiln motor and the dedusting.

To this must be added a number of smaller consumers such as the clinker crusher, clinker transport, rawmeal 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 reducedby 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 oldercyclones have a pressure loss of 100–140 mm VS, approx. 0.6–1.1 kWh/t can be saved by the exchange ofone top stage and a similar amount by the exchange of one bottom stage. (For construction reasons it isoften 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 besaved.

Some old fans with straight, radial blades have efficiencies around 65–70%, and by replacement with amodern, highly efficient type with backward curved blades, between 15–20% of the power consumption canbe saved.

An exact calculation of the pressure losses in the system may reveal other sources of savings (forexample 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 betweencooler and kiln, a reduction of the lifting capacity of the internals in the first part of the cooler so that thatless dust is swirled into that zone gives some saving. This results in a lower degree of filling in both kiln andcooler 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 ofmore air for cooling due to the reduced efficiency. If there is a thicker layer of clinker, e.g. 500–700 mm ongrate 1 and 25–350 mm on grate 2 and 3 (or additional grates) a better heat exchange is obtained and thedesired 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 requiredtemperature, more than 50% of the power consumption can be saved by the installation of an electrostaticprecipitator, which filtrates hot excess air whereby cooling air can be dispensed with. In addition, the pressureloss 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 savingin 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 aircooling. Also in this case the installation of an electrostatic precipitator can reduce the pressure loss byabout 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 aswell as estimated expenses are given. If public authorities grant subsidies to energy saving measures, a verydetailed and well documented report is almost always required.

The environmental consequences should also be evaluated, as permission for reconstructions causingmore 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 economicalconsequences.

The most advantageous proposals should be selected and submitted for approval and preparation of thefinal project.

In this phase it is often important only to propose the possibilities where the biggest of savings can beobtained, thereby ensuring the profitability of the project. If all possibilities are included, the less profitablemodifications will often conceal the profitable ones with the result that in the worst case the project will notbe 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.

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Appendix 1

TABLE 1TYPICAL RADIATION LOSSES

kcal/kg clinker kcal/kg cl

Insulation Normal HighPreheater with 4 stages and ILC-E calciner 25 15Kiln without precalcination 50 38Precalciner kiln 40 28Grate cooler and kiln hood 6 6Planetary cooler 85 70

TABLE 2HEAT BALANCE

Normal losses kcal/kg clinker

Heat loss in smoke and dust 185” ” due to radiation from preheater 25” ” ” ” ” ” ” kiln 50Reaction heat of mix 385Evaporation of water 5Radiation loss from cooler (planetary) 85Heat content of clinker 49“Free” heat input with air, raw meal and fuel −31

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Normal losses kcal/kg clinker

Net heat consumption of kiln 753

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Appendix 2

TABLE 3HEAT BALANCE

Low losses kcal/kg clinker

Heat loss in smoke and dust 178” ” due to radiation from preheater 15” ” ” ” ” ” kiln 38Reaction heat of mix 385Evaporation of water 5Radiation loss from cooler (planetary) 70Heat content of clinker 56“Free” heat with air, raw meal and fuel −30Net heat consumption of kiln 717

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

kcal/kg direct indirect clinker

Heat in kiln gases 239 196” ” by-pass gases 15 15Radiation from preheater (precalciner) 36 36Radiation from kiln 40 40

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kcal/kg direct indirect clinker

Tertiary air to coal mill 8 8Heat loss from clinker cooler 152 148Reaction heat 395 395“Free” heat −36 −33Net heat consumption of kiln system 849 796Gas temp, after preheater, °C 380 350Gas volume Nm3/min. 3420 3080” ” m3/min. 8230 7030Underpressure after preheater 960 700Consumption of electrical energy for preheater ID-fan 13.6 8.5Coal consumption, 10% H2O, t/d 446 418

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Appendix 3

TABLE 5TYPICAL EXAMPLE OF ECONOMICAL SUMMARY OF COST OF ENERGY (refer to Table 4)

Saving in Energy CostBasis: Power cost: 0.06 USD/kWh

Coal ” : 50 USD/MT coalProduction: 3000 MT clinker/dryOperation: 330 days/year

Saving in Electrical Energy Cost0.06×3000×(13.6–8.5)×330 =302,940 USD/yearSaving in Fuel Cost28×330×50 =462,000 USD/yearTotal Energy Saving

764,940 USD/year

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

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HIGH ENERGY SAVINGS THROUGH THE USE OF A NEWHIGH-PERFORMANCE HYDRAULIC COMPONENT THE

K-TECH PROCESSM.PALIARD and M.MAKRIS

CLETour TECHNIP

170, place Henri Regnault92090 PARIS LA DEFENSE Cedex 23

FRANCEand

G.MENARDI and M.BAILLYCIMENTS DE CHAMPAGNOLE

Boite Postale 33939104 DOLE Cedex

FRANCESummary

A new hydraulic binder, based on an active synthetic component burnt at low temperatureunder controlled atmosphere has been developped.

In view to optimise energy savings resulting from this new product, a specific equipment hasbeen 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 lowerthan 350 th/mt.

1.PREAMBULE

Research work on energy savings made by Société des Ciments de Champagnole since the beginning of the80’s has resulted in the development of a new type of hydraulic binder, based on an active syntheticcomponent burned at low temperature.

The process which consists in mixing the active component (the kalsin) with Portland clinker waspatented in 1984.

The industrial development of this patent results from the joint venture between SCC and CLE, whichteamed 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 experimentalburning line specifically suited for the production of the active base (kalsin) under optimised energy savingconditions.

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In December 1986, CLE-CHAMPAGNOLE was granted financial support by the Agence Française pourla Maitrise de l’Energie (French Agency For Energy Savings) for the implementation of the project to thetune of 30 % of the budget forecast.

After 2 years of continuous effort, the outcome is a great technical success: the construction of theburning line was completed in late April 1988. Start-up and industrial tests were conducted in 1988 andduring the first half of 1989.

The production of the prototype facility is now integrated on a full industrial scale at the RochefortCement Plant.

2.DESCRIPTION OF THE K-TECH PROCESS

The patented process (European Patent N° 8410186) on which the K-TECH process is based consists inproducing an active synthetic base through thermal activation under controlled atmosphere of clayed-calcareous material of specific composition and in producing hydraulic binder by mixing that base withPortland cement clinker or other activators.

Under the specific conditions of the burning process, it is possible to combine, on solid state reactionbasis, acid component of the raw mix with part of the lime of the carbonates. These reactions producesilicates, silico-aluminates, aluminates and ferrites while a proportion of carbonate is maintained withoutthermal 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, anactivated carbonated phase and low free lime content likely to develop outstanding hydraulic andmechanical 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 theabove constraints.

The raw material consists of either a single natural material or a mixture of 2 or 3 components. A largerange 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 physicalcharacteristics of the raw mix.

The reactivity of the suitably ground material in the presence of an activator likely to free calcium ionsduring hydration, such as clinker, results from:

– the mineralogical composition of the neoformed phase which contains Belite, gehlenite, aluminates andferro-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 andminor additives.

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As an indication, possible binary mixtures which can be classified as customary hydraulic binders cover abroad range from 0 to 80 % kalsin.

The mechanical performances of binders, directly related to the kalsin proportion, also depend, as for allclinkers, 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 differentkalsin 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 20–25 15–20 5–127 30–42 30–36 18–2528 45–55 40–50 30–4590 50–61 45–55 35–48% T 28 80–99 70–85 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 tothose prevailing in the rotary kiln (figure 1).

Before the construction of the present unit, tests were made in fluidized and suspension reactors of pilotescale. 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 forconfinement of material under high CO2 pressure level.

Preliminary studies have shown that better results were obtained if the material could be quenched undermoderated CO2 pressure level.

For optimisation of energy consumption, recovery of sensible heat of combustion products and kalsin iscarried 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 duringerection (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 kilnand 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 ofthe installation to variations of raw meal flow rate or combustible flow rate for short periods of time didn’taffect the performances of the calciner.

Heat and power requirements are listed in the table (1) for present conditions in the industrial unit of SCCin 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 testreactivity 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 cementmanufacture. Like for cement, their chemical and mineralogical composition determine the reaction kineticsduring 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 burningtemperature 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 theROCHEFORT plant (FRANCE) constitutes a major improvement in the composite cement technology. Itsmain 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

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– environmental protection.

TABLE 1. KCC burning line performances

PRODUCTION RATE Present Up to 300 T/J 1200 T/JHEAT CONSUMPTION Present Down to 300/350 Th/h 280 Th/hPOWER CONSUMPTION Present Down to 18/20 kWh/t 15 kWh/tGRINDING RAWMEAL AND KALSIN

Present Down to 35 kWh/t 25 kWh/t

Fig. 1. K-Tech burning line

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Fig. 2. K-Tech-KCC burning line

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Fig. 3.

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Fig. 4.

Fig. 5.

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Fig. 6. K-Tech burning process pilot stage

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Fig. 7.

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Fig. 8.

HIGH ENERGY SAVINGS 135

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ENERGY MANAGEMENT IN THE U.K. CEMENTINDUSTRY

Dr T M Lowes, Energy ManagerMr K W Bezant, Technical Services Director

Blue Circle Industries PLCTechnical Services Division

305 London RoadGreenhithe

Kent DA9 9JQ

SummaryInformation 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 30years. Details are given on the approach in BCC to Energy Management. Recent achievementsin energy reduction via the development and application of flame, milling and expert systemtechnology are highlighted. Plans for energy cost reduction in the future, are outlined withreference to the Department of Energy’s assessment of the potential for energy reduction in theCement Industry.

1.BACKGROUND

As a consequence of the chemical reactions and physical operations involved, the cement manufacturingprocess is a high energy user. The reactions necessary to produce the mineral structure of cement take placeat a high temperature in the range 1400 to 1600°C. To ease these reactions, the raw material has to be veryfinely 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 electricityenergy requirement in excess of 2 TeraWatt hours and at approximately 2 million tonnes per annum is thelargest user of pulverised coal in the private sector. The overall energy bill is in excess of £150 million andrepresents approximately 40% of production costs. Hence, energy management is an important discipline inthe Cement Industry.

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Cement making processes can be divided into two broad categorie— the wet and dry processes. The twomajor intermediate variants are the semi-wet and the semi-dry processes. All four of these methods arecurrently used in type of process used has an important bearing on the amount and form of energy requiredto produce cement clinker. Table 1 shows a typical breakdown of the distribution of energy consumption inthe manufacture of cement. This shows that while there is lower fuel consumption in the dry process due tothe lower evaporative load, a higher electrical consumption is encountered, due largely to the dry rawmaterial preparation (grinding, pneumatic conveying and blending) being more energy intensive.

TABLE 1—TYPICAL ENERGY CONSUMPTION IN CEMENT MANUFACTURE (KWH/TONNE)

WET PROCESS DRY PROCESS

Raw material winning and preliminary crushing 3 4Raw material fine grinding and blending 10 44Coal preparation and firing 10 6Kiln system (ID fan and cooler) 25 23Dust collection 8 6Cement grinding 45 45Despatch 8 8Total electric power 109 136Kiln fuel (1384 kcals/kg) 1610 (858 ks/kg) 998

1719 1134==== ====

The major area of energy consumption, whatever the process, is the heat treatment of the raw materials toform the clinker, which is subsequently finely ground to produce cement. However, the energy consumedduring cement grinding and in dry raw material preparation is also extremely significant. Table 2 shows thecontribution of Blue Circle Cement’s fuel and power to its production costs over a thirty year period. Thelevel of total energy used—up to 50% total production costs—stimulated an initiative to reduceconsumption long before the OPEC driven escalation in energy costs of the ’70s. Modern managementtechniques are naturally applied to all resources, and with energy being such a high percentage of costs, ithas always been at the top of the priorities. Blue Circle appointed its first Energy Manager in the ’20s whencoal was only five shillings a ton.

TABLE 2—BLUE CIRCLE CEMENT

PRODUCTION COSTS

TOTAL FUEL POWER WAGES DEPRN OTHER

1955 100 41 13 16 10 201965 100 31 13 19 8 291975 100 25 16 22 15 221985 100 31 14 18 13 24Note: Delivery cost add approximately 33%

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Figure 1 shows how Blue Circle’s fuel consumption has generally dropped over the last 15 years (someincrease 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 beendue principally to the extra electrical power required to operate Works at lower feed moistures more thanoffsetting gains that have been made through more efficient power usage. The more recent steep increase isdue mainly to finer grinding being employed in order to meet the demand of the concrete industry forhigher 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 ofOrdinary Portland Cement resulting from over-capacity and common pricing (now terminated). Hence, the1989/90 kWh/tonne will again be lower.

The reductions have been achieved by ensuring that appropriate effort has been put into the importantareas associated with energy conservation, namely: Good Housekeeping, Application and ExistingTechnology and the Development and Application of New Technology. Each of Blue Circle’s 12 UKWorks has an Energy Management Plan, covering both energy consumption and cost for the current andfuture years. This is backed by strong Main Board and management commitment to achieving energysavings 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 overthe last 20 years. Due to these trends, energy costs have remained a similar percentage of total productioncosts, despite significant reductions in average fuel consumption. An increase in the cost of fuel and energyin 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 theextra costs could not have been passed onto the customer. These average energy costs have been reduced bya combination of improved supplier’s efficiency, negotiation, QUICS and optimum use of tariffs. Thus, aproportion of the recent increases in electricity prices ( ) to the Cement Industry as a prelude toPrivatisation, will have to be passed onto the customer.

FIG. 1

BLUE CIRCLE CEMENT

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Until recently the UK and general world cement market has remained largely static. Therefore, tomaintain a viable cement business, operating costs have had to be minimised. Unfortunately, in the UK thecost of building a new greenfield site dry process works (e.g. £150M for an annual capacity of a milliontonnes of cement) does not meet acceptable investment criteria, so that the approach of using an entirelynew process design to reduce energy consumption has not been viable. Thus, in practical terms, energyconsumption can only be reduced via cost-effective modifications to existing Works and the developmentand application of novel technology, backed by effective energy management techniques. A similarsituation will exist in the future unless the current upturn in the market creates a permanent requirement fora higher UK production capacity. Blue Circle has over 50% of UK cement sales. A significant part of thecurrent national approach to reducing energy costs can therefore be readily outlined by reference to BlueCircle Cement’s own activities.

2.ENERGY MANAGEMENT

Within Blue Circle Cement, Energy Management incorporates both the cost and specific consumption ofenergy.

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. On-line monitoring is used as appropriate, bearing in mind that all the fuel is pulverised coal and the product iseither 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 theenergy consumption is divided into a range of departments, each with its target and appropriate monitoringactivities. The targets are set by the Technical Centre in conjunction with the Works and is based onexperience and what is theoretically/technically possible for the plant. Maximum effort is made to ensure

FIG. 2

BLUE CIRCLE CEMENT

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that the Works’ team is aware of their targets and what they can do to meet them. Techniques have beendeveloped 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 beenidentified, evaluated and broadly costed in conjunction with the Technical Centre. These are reviewed withthe Energy Manager on an annual basis. Items are then included in Blue Circle’s capital plan whenappropriate.

Coal purchasing is negotiated centrally but no negotiation is yet possible on Electricity Tariffs. TheWorks and the Technical Centre are continually looking at the possibility of using lower grade fuels andoptimising the use of the CCL and Load Management Tariffs to ensure that the lowest average unit price isachieved.

Blue Circle Industries’ position as a major International Cement Manufacturer and Consultant, ensuresthat 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 mostconveniently described in relation to the recent DoE evaluations and projections of the impact of a range ofenergy conservation possibilities, which are reproduced in Table 3.

FIG. 3

BLUE CIRCLE CEMENT

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

EFFICIENCY MEASURES 1990 2000 FUEL SAVINGS

1. + Wet to semi −wet conversions 8.0% 8.0% Coal2. Wet to dry conversions 4.0% 12.0% Coal3. + Improved combustion control 2.0% 2.0% Coal4. + Wastes as fuel 2.5% 5.5% Coal5. # Blended cements 1.0% 3.5% All6. + Improved kiln insulation 3.0% 3.0% Coal7. # Improved grinding technique 0.3% 0.7% Electricity8. # Waste heat utilisation 2.5% 5.5% Electricity and Heating Fuel

* Total Saving 21.1%(595,000 tce/a)

34.1%(960,000 tce/a)

+ 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 semi-dry Works to dry process/ pre-calciner operation at a total cost of over £100 million, with projected fuelsavings of 20% and 15% respectively. Also, a number of small wet process kilns have been taken out ofservice. 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 energyreductions in the next few years will result from applying recently developed technology. This technology isassociated with flame design and high level kiln control, together with the planned maintenance andappropriate energy management techniques needed to achieve steadier lower energy operation. Fuel savingsof up to 10% as well as a reduced NOX emission, have been demonstrated for the use of flame designtechniques to eliminate reducing conditions in the clinkering zone of a kiln, coupled with mini computerbased high level linguistic control of combustion and kiln operation to produce an optimally processedclinker. In addition, a more reactive cement is produced, steadier running is achieved and an improvedrefractory life can be expected. This development has been assisted by funds from both DoE and DoTI andis currently being extended to all Blue Circle Works. The system is now operating successfully on 5 of BlueCircle’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 capitalinvestment to be applied. The financial investment criteria required to make this attractive to both localauthorities and cement makers are not generally achieved, due principally to the availability of adequatelandfill sites in most areas. There may also be a reduction in production capacity as a result of using lower gradefuels, which is costly when full output is required to meet demand. The use of gas generated from domestic

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waste used as quarry fill has been developed, as in the brick making industry, and is being used to replaceup to 40% of the prime fuel on Swanscombe Works.

Increased Environmental Regulations relating to the disposal of industrial wastes in the 1990s, will createan opportunity for the Cement Industry to use processed waste oils and solvents at up to 25% prime fuelreplacement. However, care must be taken as the water and minor chemical constituents increase fuelconsumption 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 producedhas different characteristics and these have to be accommodated in concreting practise. BS12—the BritishStandard which specifies the majority of cement made by the Works and used in practise—does not permitthe 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 beachievable.

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, arethe major current concern and this is subject to considerable investigation. Improved insulating refractoriesfor high temperature zones—when developed—will undoubtedly result in an energy saving, providing noreduction in operational life is encountered.

IMPROVED GRINDING TECHNIQUES (7)

Application of ball mill simulation techniques is achieving up to 20% reduction in energy consumptionon 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 andefficient separators offer the possibility of reducing the energy consumption for cement milling by up to afurther 20%. Blue Circle are currently installing more efficient separators where an appropriate financialcase 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 useof the appropriate Rankine cycles could allow up to 20 kWh/clinker tonne to be generated from the coolerand preheater exhausts of an existing four stage dry process kiln system. Generally, the projected financialreturn makes the possibility only viable for a new Works where no other use has been found for the surplusheat. The most appropriate approach for all Works is to minimise the waste heat produced; this makes theprospective use of waste heat for power generation even more uneconomic. However, the forthcomingPrivatisation of the Electricity Supply Industry may change the economics in terms of the financial benefitsof having in-situ generating capacity. Power generation at the 10 kWh/tonne level using the ORC coupled tothe 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 MainBoard. Works’ Management are committed to achieving projected reductions aided by Technical Centreresources. The application of the two recent developments— items 3 and 7—are and will have a signficantimpact on the energy efficiency operations in a cost-effective manner, with early paybacks. The computersinstalled for the high level kiln control are also being used to enhance the Works’ energy management viagood housekeeping. On some Works, reductions in total fuel and electrical energy consumption of at least10% 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 similarnationwide levels of improvement in energy consumption.

Future scenarios project a low energy consumption, minimum manned cement works with almost completecomputer control via novel sensors for the on-line control of raw material/clinker characteristics. BlueCircle are already well down the path with the development of high level control and the introduction ofIntegrated Working.

1992 will reduce the average fuel consumption per tonne of ‘cement’ sales, by extending the use ofcomposite cements. However, the increasing pressure of the Environment, which is loosely associated with1992, in terms of dust, NOx and SO2 emission, will increase both fuel and electrical energy consumption aswell as operating costs.

The forthcoming Privatisation of the ESI will have a tendency to reduce electrical energy consumption ifRegulation does not stop their rapidly spiralling charges, due to to marginal investments becoming moreviable.

There is much to be done and the Cement Industry has the will and economic drive to do it. DoE target of34% savings in energy by the year 2000 identifies the potential for great rewards. However, a stableeconomey and low interest rates over an extended period are needed for investment in long life, capitalintensive plant.

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“WASTE GAS HEAT RECOVERY IN CEMENT PLANTS”MARQUES NETO

General Manager of Souseias Cement PlantCIMPOR, E.P.

1.INTRODUCTION

With the current available technology for cement manufacturing, the burning phase is, as well known, andamong 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 orlarge capacity, and with pre-heater towers where raw-materials are presented with low moisture (andtherefore with small consumption of kiln gases for drying) there will be considered amount of hot gasesavailable 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 studythis 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 heatwasted In the burning process.

In fact, with crude raw-materials of about 5% moisture contents, a dry-process burning line, with a kilnof medium capacity (1600 t/day), 4 stage pre-heater tower, and grate cooler, enables a production of electricenergy of nearly 30 KWh/ton of clinker, from a turbo-generator set which turbine receives the steamproduced, in suitable boilers, by effect of the hot gases of the burning process and hot air of the clinkercooling.

The researches have also pointed out that the “waste heat recovery project” is only profitable when one isfaced 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 theeuropean 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 followingpower features:

POWER STATIONS

Run-of-the river Hydro-storages ThermalPower (MW) 1660 988 2129Max. Guaranteed Power (MW) 3897Peak Consumption (MW) 4390

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, thestimulation 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 cementproduction 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) represented48% 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 costof 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, whichrepresents electric energy consumptions of about 200 GWh per year, and due to the high cost of the kwhsupplied, 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 specialisedcompanies in this matter have been contacted, being elected NIHON CEMENT COMPANY (NCC), aJapanese Company from Tokyo, with well succeeded experiences in this field.

Based on a preliminary study developed together by NIHON, 1ST (Engeneering Faculty of the TechnicalUniversity of Lisbon) and CIMPOR itself, the project “Waste Heat Recovery in Cement Plants” has beenpresented to the Commission of the European Communities on April 1988, as an Energy DemonstrationProject to be installed in Cimpor (at Souselas Cement Plant). Later, in November, a subsidy on the amontequal 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 maincharacteristics are as follows:

Line 1 Line 2 Line 3Start up of the production (year) 1974 1975 1982Kiln capacity (t/day) 1600 1600 3500Size of the kiln (ø×lenght) 4,6×70m 4,6×70m 5×75mPre-heater tower 4 stages 4 stages 4 stages

(Dopol)Cooler Grate Grate 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 fromthe 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 effectivepower 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 fromNIHON CEMENT CO. This project does not aim at either an increase in the cement production, or achange 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), thefollowing cost distribution:

Boilers (5 units) ...........…. 1100 Million Escudos

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Turbine and auxiliaryequipment........................ 250 ” ”Electric equipment.............. 220 ” ”Erections........................ 220 ” ”Civil works.......................... 210 ” ”Various........................... 100 ” ”Tests and measurements........... 10 ” ”

2110 Million Escudos

The Project will be financed through Cimpor’s own funds, completed by 2 subsidies, one from EECand another from the Portuguese Goverment, with the following distribution:

Cimpor’s own funds.............. 1578 Million EscudosEEC 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, at1988 prices, would be approximately 580 million Portuguese Escudos; being the cost of exploitationforeseen 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 costsupported by Cimpor).

4.3 The project shall be performed in 4 phases, planned in the following way:

Phase 1: Project execution and tendering—Till the end of May 1990 (it is foreseen to signthe “turn-key” contract with the supplier on that date);

Phase 2: Fabrication and Erection—From June 1990 until the end of 1991;Phase 3: Training and Commissioning—From October 1991 until March 1992;Phase 4: 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 areintegrated.

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DISCUSSION

TO: MR BLANCKMR S I NYAGBA, Benue Cement Co Ltd, Nigeria

QUESTIONWhat information would need to be input to achieve the long-term projected savings?ANSWERInitially we record all the energy consumption levels and then store them in a data base. From thiswe compare energy consumption with output, operators and any other relevant criteria.

MR NOHLMANS, Novem, Netherlands Agency for Energy

QUESTIONWe 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?ANSWERTo do this you need to reduce the data but enhance the information. The operator needs short-terminformation so that he can react and make the necessary changes to maximise energy efficiency.

TO: MR DUMAS AND MR CASSOUMR J F SOARES, Cimento CAUE SA, Brazil

QUESTIONHow long did it take to convert the grate cooler?ANSWERBetween two and two and a half months.

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MR FUKUSHIMA, NCC, Japan

In connection with the free lime analyser, how often do you analyse free lime?ANSWERTwice every hour.QUESTIONWhere do you set up this monitoring instrument?ANSWERThe sample is taken at the outlet of the kiln before the cooler.QUESTIONDoes the expert system work effectively using the free lime analysis data? ANSWERThe expert system is linked to the control and command system already installed and the setpoints are modified using data from the free lime analysis.

MR MENDONCA GOUVEA, Alsthom International, Portugal

QUESTIONWhat was the role of CITEC in the modifications described?ANSWERCITEC contributed with the design of modifications and consulted with manufacturers.

TO: MR BIRCHDAVID HASPAL, ‘Linkman’ Image Automation, United Kingdom

QUESTIONRegarding going from direct to indirect firing, saving 25 kCal/tonne, could you comment on theextra cost of running indirect systems like the replacement of the firing pipes and the extraelectrical energy required for the fans. These costs may offset some of the savings claimed.ANSWERExact figures are not available. As you say, there are not only benefits there are some costs whichshould not be ignored.

TO: MR PALIARD and MR BAILLEY

QUESTIONHas your material achieved full technical acceptance in France?ANSWERThe cement is used in road making and other areas where its properties are acceptable.

TO: DR T LOWES—No questions.TO: MR TAKAKUSAKIMR STEINBISS, KHD, BR Deutschland

QUESTIONWhat do you mean by a raw material by-pass?ANSWERBecause 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

QUESTIONHow do you propose to deal with fouling on the heat exchanger surface?ANSWERThis is avoided by inclusion of soot-blowers and water washing.

After this question and answer session, the delegates visited CIMPOR’s Souselas Plant.

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

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ROUND TABLE DISCUSSIONChairman: Professor Mario Nina, University of Lisbon

Contributors: K W Bezant, Blue Circle Cement, United KingdomF Aellen, Holderbank, Switzerland

Professor G Parisakis, University of Athens, GreeceJ Sirchis, Commission of European Communities

E Steinbiss, KHD, BR DeutschlandH 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 thetwo 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 wasanticipated that per capita demand would increase to between 227 and 257 kg. Total demand in Europe wouldbe 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 fallsshort of the most pessimistic level of demand. To satisfy the increased demand it is considered that between50% and 70% of the increased capacity will come from modifying existing plant. The remaining shortfallwill be met by new plant. To increase output will require an investment of between US $6 and US $22billion. 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 fuelconsumption by 5%/annum to remain at the same current overall level of energy consumption. To reduce

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overall demand for energy in the cement industry will involve an annual reduction in specific energyconsumption by more than 5%/annum.

3.ENVIRONMENT

MR AELLEN of Holderbank commented on the environmental impact of the cement industry. The Swisslimitations were similar to those applied in West Germany which are currently:

mg/m3

Dust emission 50Ammoniac 30Chlorhydrogen 30Sulphur dioxide 500NOx NO2 750

Technology exists to reduce dust levels to 15 mg/m3. Sulphur dioxide emissions can be reduced by mixinglime hydrate with the raw meal feed or introducing it after the conditioning tower. These methods havereduced SO2 emissions to less than 500 mg/m3. NOx emissions have been reduced by lowering the kilntemperature 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 CO2emissions. Currently most cement in Europe is produced using coal. For each tonne of clinker producedwith coal there is one tonne of CO2 discharged into the atmosphere. This emission could be halved if coal wassubstituted with natural gas.

MR TAKAKUSAKI, NCC, Japan stated that the Japanese limits were:

NOx 480 ppm @ 10% oxygen contentDust 100 ppm/m3

SO2 30 ppm

To achieve these levels, primary air must be reduced to less than 7%. One kiln has been successfullyoperated at less than 4% primary air resulting in reduced levels of NOx. Also at the outlet from the firststage 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 NOxemissions.

Dust burdens are being reduced by the use of electrostatic precipitators. The oxygen level at theelectrostatic precipitator is around 7%. Providing the whole process is under effective control, NOx levelsshould be at an acceptable level.

CO2 emissions can be reduced by the use of branded cement. There were no examples of SO2 controlprovided.

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The Chairman, PROFESSOR MARIO NINA, University of Lisbon, contributed by giving the relativequantities of CO2 emissions when burning different types of primary fuel:

Gas = 1Oil = 1.32Coal = 1.52

Significant scope exists to reduce overall energy demand by 15 000 tonnes of oil equivalent by theincreased 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 ofpayments?

iii Predicting the future price of energy and current exchange rates make it difficult to determine whetheran investment will be worthwhile. The cement industry is capital intensive and most plant has betweena 20 and 40 year life.

5.EUROPEAN NORMS

MR BEZANT, BCC, stated that Env.197 has not been accepted as presently drafted but should beintroduced by 1992/93. When accepted, this will reduce the total energy content of cement and mortar byenabling more fillers to be introduced. Increasing the filler content of cement will reduce the rate at whichnew 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 losttwo 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. Steadyimprovements have been made by introducing first the semi-wet process, then the dry process and finallycalciner kilns giving reductions to 700 kCal/kg clinker. It is only poorer performing countries that havesignificant scope to improve efficiency.

Waste heat recovery can be used to win back some of the wasted heat. This is only suitable for larger kilnswith exhaust gases with low moisture contents.

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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, 200machines 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. Theprojects discussed had been interesting but none represented a dramatic breakthrough. There were very fewcases of revolution, only evolution.

The UK cement industry has a target of reducing energy consumption by 20% to 700 kCal/kg. Such areduction would be difficult in Japan and other countries which are already achieving these levels ofconsumption.

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 cementindustry is not particularly glamorous and there may be a problem attracting quality staff. One challenge forthe 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.

QUESTIONMR TAKAKUSAKI, NCC, Japan, asked what the operational level was in the European cementindustry.ANSWERMR BEZANT, BCC, advised that in the UK (Blue Circle Cement) the target is 90% which is notalways achieved. Planned maintenance in January/February shutdowns accounted for 5% outputand none planned between 3% and 5% is fairly typicalQUESTIONMR PALIARD, CLE, France, Question to MR STEINBISS regarding the roller press. Do youthink that the roller press of the classification system is the reason for the shape of the curve?ANSWERThe size distribution is closer than that from a ball mill. The cement produced from a roller milltends 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 eitherfor heating or for electrical energy production. There has been no mention of heat recovery for cooling andthere is an example of this in Portugal, which may not have any precedent. CIMPOR has a system forheating and cooling using waste heat from the clinker cooler. This is on a kiln with an output of 1350tonnes/day. They recycle around 50% of the exhaust fumes at a temperature of 180–200°C (around 50000m3) in order to recover heat using a boiler with a capacity of 1.2 MW. This heat is used for heating a largesack factory with an area of around 12000 m2. In addition, the heat is used to heat technical andadministrative offices in winter. Cooling is provided in summer from a chiller plant set up using the Lithiummethod with a power capacity of around 0.8 MW. Savings equivalent to around 30 million escudos/annumof electrical power are achieved. Heating accounts for savings of 20 million escudos and cooling accountsfor 10 million escudos. The payback period is less than two years.

QUESTION

ROUND TABLE DISCUSSION 155

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TOM LOWES, BCC, to Holderbank and MR STEINBISS regarding the installation of KHDburners where it was stated that reductions of up to 40% in oxides of nitrogen were achieved. Couldyou tell us the level you were at to begin with and what you went down to? Did you have anysignificant increase in fuel consumption, instability in the kiln or SO2 emission? In Blue Circle wehave found that we can reduce oxides of nitrogen by eliminating reducing conditions in the kiln.ANSWERThis 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 ofthe 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 beenlowered. 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 NOxemissions in kilns with planetary coolers. In kilns with grate coolers, reductions were between1000 and 1800 mg/m3.

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CLOSING SESSIONChairman: V Teixeira Lopo, President of CIMPOR

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CONCLUSIONSby 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 toimproving energy efficiency in clinker manufacture. The overall effect of the transfer from wet to dryprocess 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 incement for ordinary concretes compared with the industry in other major world areas. The energysaving 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 inthe selection of energy supplies. For high grade funds, it has responded quickly to market trends andmost plants can handle a variety of fuels, or mixtures of them. It has become the principal consumer ofpetcoke. This is an important contribution to EC Energy Policy as it reduces dependence on individualsources.

4. The industry therefore welcomes all EC actions directed to keeping available every possible energysource.

5. Contrary to the situation for kiln fuel, the cement industry has no choice as regards electricity, the costof which in some plants is as high, and can even exceed that for the kiln fuel. The industry equallysupports therefore EC efforts towards the liberalisation of the electricity market, giving access to thegrids 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 wouldotherwise be dumped, should be recognised. The EC principle that the polluter pays is an acceptableone. However, it is necessary to be clear about the transfer of responsibility. The industry whicheliminates this environmental problem should not be equated with, or treated in the same way as theindustries which produce the waste products.

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

CONCLUSIONS 159

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ABREU C.SEC.ESTADO ENERGIARua Horta Seca 151200 LISBOAPORTUGALABREU MarioLNETIAzinhaga Dos LameirosEstrada Do Paco Do Luminar1600 LISBOAPORTUGALAHLKVIST BOCEMENTA ABPO Box 102 S-620 30SLITESWEDENANINGO C.C.BENUE CEMENT COMPANY LTDP.M.B. 12702LAGOSNIGERIABAGUENIER H.CENTRO ESTUDOS ECON.ENERGIARua Miguel Lupi, 201200 LISBAOPORTUGALBARALIS R.ITALCEMENTIVia G.Camozzi, 12424100 BERGAMOITALYBARREIRQ Antonio CaldSECILOutão2900 SETUBALPORTUGALABREU Carlos M.

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Rua Miguel Lupi, 201200 LISBAOPORTUGALBARALIS R.ITALCEMENTIVia G.Camozzi, 12424100 BERGAMOITALYBARREIRQ Antonio CaldasSECILOutão2900 SETUBALPORTUGALABREU Carlos M.SECILOutao2900 SETUBALPORTUGALAELLEN F.HOLDERBANKPO BOX 8750GLAIRSSWITZERLANDANDRADE S.CIMPORCentro de Prod. de Souseias3000 COIMBRAPORTUGALAZIZZ Hamouda A.ALEXANDRIA PORTLAND CEMENT COP.O.S. El MexALEXANDRIAEGYPTBAILLY M.CIMENTS DE CHAMPAGNOLE21, rue Clauzei75009 PARISFRANCEBARRACHA FR.DIRECAO-GERAL QUALIDADE AMBIENTERua do Século, 511200 LISBOAPORTUGALBENITO Frederico AdrianHORNOS IBERICOS ALBA S.A.

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Nunez de Balboa, 35-A28001 MADRIDSPAIN BERTRANDASLANDOrense, 8128020 MADRIDSPAINBEZANT K.W.BLUE CIRCLE305 London Road GreenhitheKENT DA9 9JQU.K.BLANCK M.HOLDERBANK MAN.&CONSULTING LTD5113 HOLDERBANKSWITZERLANDBORGES H.A.SOCIEDADE CIMENTO NAC.DE MINAS S.A.Apart.11-Torre da Marinha2842 SEIXAL CODEXPORTUGALBREUERALLMINERAL AUFBEREITUNGS TECH. GmbhVulkanstrasse, 364100 DUISBURG 1GERMANYBUHLMANNASEA BROWN BOVERI LTD5401 BADENSUISSECAMPOS E.CIMPORRua Alexandre Hercuiano 351200 LISBOAPORTUGALBESSAD HamedENFIDA CEMENT INDUSTRIEBN7–4030 ENFIDHATUNISIABIRCH E.F.L.SMITH77, Vigersiev Alle2500 VALBY COPENHAGENDENMARK

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BOLLER NikolausCIMINAS-Cimento Nac.de Minas S.A.Vargem Alegre-Calxa Postal 2033.600 Pedro Leopoido-M.G.BRASILBOUQUELLE J.F.CIMENTS D’OBOURGSRue des Fabriques, 27048 MONS OBOURGBELGIUMBROCKHAUSEN UDO SCHULZECHRISTIAN PFEIFFER GmbhSudhoferweg 110/1124720 BECKUMGERMANYBURGUERA J.CORPORATION NOROESTESan Salvador, 2–4°36204 VIGOSPAINCANDEIAS Manuel J.SengoPRECISALLargo Conde Barao, 34–2° Esq°1200 LISBOAPORTUGAL CARDOSA e CUNHACCE200 rue de la Lol1040 BRUXELLESBELGIUMCARVALHO C.CIMPORCentro de Prucao de Souselas3000 COIMBRAPORTUGALCASTELA A.CIMPORCentro de Producao de Maceira2400 LEIRIAPORTUGALCHEAH ALLEN H.M.WISMA APMC, 2Jalan Kilang46050 PETALING JAYASELANGOR

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MALAYSIACLARCK D.P.STEELEY QUARRY PRODUCTS LTDMiddleton St GeorgeDARLINGTONCO DURHAM DL2 1HRU.K.COELHO C.LNETIPraça do Principe Real, 191200 LISBOAPORTUGALCOLLOMB B.LAFARGE COOPPEE28, rue Emile Meunier75782 PARIS CEDEX 16FRANCECARRERCIMENTS DU KAMEROUNB.P. 1323DOUALAKAMEROUNCASSOU D.SOCIETE DES CIMENTS FRANCAISLes Technodes78931 GUERVILLE CedexFRANCECATALAO J.EURANTICApartado 172766 ESTORIL CODEXPORTUGALCIFUENTESPOLYSIUS S.A.PI.Manuel Gomez Moreno s/nEd.Bronce28020 MADRIDSPAINCOCHET Francis5, bd.Louis Nucher92211 St CLOUDFRANCECOLLISCEMBUREAU55 rue d’Arion

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1040 BRUXELLESBELGIUMCONSO P.CIMENTS FRANCAISTour Générale-Cedex 2292088 PARIS LA DEFENSEFRANCE CORREA VirginiaDIRECCAO GERAL DE ENERGIARua Da Beneficencia 2411600 LISBOAPORTUGALDAMATO MichelPOLYSIUS S.A.30, Bd.Beilerive-BP 24392504 RUEIL MALMAISON CedxFRANCEDEKKICHEA.B.B. Department ITE5401 BADENSWITZERLANDDIVINOCOMP.DE CIMENTO PORTLAND PARAISOAv. Rio Branco, 103/18° Centro CEP20040 RIO DE JANEIROBRASILDUMAS J.CIMENTS FRANCAISLes technodes78931 GUERVILLE CEDEXFRANCEEL DALLY AHMED F.SUEZ CEMENT CO35 Ramses streetNile Bank BuildingCAIROEGYPTEL MIKENY AHMEDalexandria Portland cementP.O.B. El MexALEXANDRIAEGYPTCOUTINHO F.CIMPORCentre de Producao de Patalas

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2430 MARINHA GRANDEPORTUGALDE TERVARENT P.DE SCHOUTHEETE62, rue Belliard1040 BRUXELLESBELGIUMDENTON John T.CASTLE CEMENT LTDClitheroeLANCASHIRE BB7 4QFU.K.DUFRESNOY FrederiqueGEC Alsthom141, rue Rateau93123 LA COURNEUVEFRANCEDURAO D.INTERG I.S.T.Av. Rovisco Pais1096 LISBOAPORTUGALEl Gabry NabilHELWAN PORTLAND CEMENT COP.O.Box 16HELWANEGYPTEL NADY FEKRY ABDSUEZ CEMENT CO35 Rambes streetNile Bank BuildingCAIROEGYPT EL TOUNNYNATIONAL CEMENT CO5–26 July streetPO Box 18CAIROEGYPTESOKAMBASOCIETE DES CIMENTS DU GABONB.P. 477LIBREVILLEGABONFERRANDO J.COMP.VALENCIANA DE CEM.PORTLAND

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Colon, 6846004 VALENCIASPAINFLAMENT G.SOCIETE DES CIMENTS FRANCAISLes Technodes78931 GUERVILLE CedxFRANCEFRADERA EnriqueUNILAND CEMENTERA S.A.Corceqa, 29908008BARCELONASPAINFUJIRAWA T.TAKUMA CO LTD3–23 Dojima Hama I-ChomeKITA KU OSAKA 530JAPANFURTADO F.ASEA BROWN BOVERIAv. Cons.Fernando Sousa 251000 LISBOAPORTUGALELWAY MAHMOUDNATIONAL CEMENT CO5–26 July streetP.O.Box 18CAIROEGYPTETOCASS.TEC.IND.LIANTS HYDRAULIQUES8, rue Villiot75012 PARISFRANCEFERREIRA José BravoSECILOutao2900 SETUBALPORTUGALFLAUX Jean PierreGEC Alsthom141, rue Rateau93123 LA COURNEUVEFRANCEFRITZ

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CIMENTS DU TOGO11687 LOMETOGOFUKUSHIMA H.NCC OHTEMACHI BLDG6–1 1-Chone Ohtemachi ChiyoTOKYOJAPANFYNES GeoffreyBRITISH COAL CORPORATIONStoke OrchardCHELTENHAM GL52 4RZGREAT BRITAN GERMER A.NORICUMPostfach 38940 LIEZENAUSTRIAGOMES A.SOARESCIMPORRua Alexandre Hercuiano 351200 LISBOAPORTUGALGRIBATALLMINERAL GMBH CO.KGVulkanstrasse 364100 DUISBURG 1GERMANYGUPTA R.K.J.K. CEMENT WORKSKamla TowerKANPURINDIAHAN BANG YUNMANIL CEMENT MFG.CO832–2 Yuksam DongKangnam KuSEOULKOREAHARGREAVES D.INTERNATIONAL CEMENT REVIEUW320 High street, DorkingSURREY RH4 1QYU.K.HASPEL D.W.

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Kelvin HouseWorsley Bridge Road SydenhamLONDON SE26 5BXU.K.GOCER C.ADANO CIMENTO SANAYII T.S.A.Ceyhan Yolu Uzeri 12kmADANATURKEYGOUVEA Bernardo MandoncaALSTHOM INTERNATIONALApartado 13621011 LISBOA CodexPORTUGALGROZELLIER J.P.CIMENTS DE CHAMPAGNOLEBP 33930104 DOLE CEDEXFRANCEHAILERPOLYSIUS S.A.PI.Manuel Gomez Moreno s/nED.Bronce28020 MADRIDSPAINHANDOYO JUFRIWISMA INDUCEMENTLevel 13/PO Box 4018JL.Jend Surdinam Kau 70–71JAKARTA 12910INDONESIAHARTOWOSEMEN ANDALAS INDONESIAA1ced Office Lho Nga Km 16BANDA ACEHINDONESIAHASSEN K.HELWAN PORTLAND CEMENT COPO Box 16HELWANEGYPT HAWKINS J.ARAWAK CEMENT COMPANY LTDChecker HallSt Lucy

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BARBADOSCENTRAL AMERICAHIGASHIMURAEURANTICApartado 772766 ESTORILPORTUGALHOMASSEL BernardLAFARGE COPPEE28, rue E.Meunier75782 PARISFRANCEHUNZIKER PAULINDUSTRIA NACIONAL DE CEMENTO S.A,Apdo.4009–1000SAN JOSECOSTA RICACENTRAL AMERICAJARRETT PATChecker HallSt LucyBARBADOSCENTRAL AMERICAJIRI PTACEKCEEKwerpsebaan 1533071 KORTENBERGBELGIQUEKARRASH GerdHORNOS IBERICOS ALBA S.ANunez de Balboa, 35_A28001 MADRIDSPAINHENSGEN H.O & K ORENSTEIN KOPPELBresiauer Strasse 274722 ENNIGERLOKGERMANYHO YEON LEEHYUNDAI CEMENT COAn 2–1 Jamwon DongSeo Cho KuSEOULKOREAHOUBER

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BAMBOURI PORTLAND CEMENTP.O.Box 90202MOMBASSAKENYAIN YOUNG LEESSANGYONG CEMENT INDUSTRIAL COSsangyong Blgd.24–1 2-GAJeo Dung Junk GUSEOUL 100–748KOREAJHALORI K.K.BRITISH COAL CORPORATIONKamla TowerKANPURINDIAJONGEN J.H.ENCI NVPostbox 16200 AA MAASTRICHTNETHERLANDSKAUFFMANN Jean PaulPOLYSIUS S.A.30, Bd Belierive-BP 24392504 RUEIL MALMAISON CedexFRANCE KESMEZ H.ADANO CIMENTO SANAYII T.S.A.Ceyhan Yolu Uzeri 12 KmADANATURKEYKIM KWANG SOO832–2, Yuksam DogKangnam KuSEOULKOREAKINDERMANN F.CCE200 rue de la Loi1049BELGIUMKLINCKHAMERSLCEMENTFABRIEK ROZENBURG ROBURP.O. Box 1030–3180 AAROZENBURG ZHNETHERLANDS

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KONIG HERRNABTEILUNG FORSCHUNG + ENTWICKLUNG3320 SALZGITTER 41GERMANYLASUDSAKU OidijaiJALAPRATHAN CEMENT CO2974 NEW PETCHBURI ROADBANGKOK 10310THAILANDLEITAO F.CIMPORRua Alexandre Hercuiano 351200 LISBOAPORTUGALKHORASSOCIATED PAN MALAYSIA CEMENT SDNRawang Works48000 RAWANGSELANGORMALAYSIAKIM SEUNG BAESSANGYONG HEAVY INDUSTRIES CODong Hae Plant/200, Samwha DongKwanngwon Do240 350 SEOULKOREAKIRDRATANASAK SANYAJALAPRATHAN CEMENT COTakli Factory1 Jalaprathan Cement Road TakilNAKORNSAWAN 60140THAILANDKNUDSEN PerGOTLANDS ENERGIVERK ABP.O.Box 17620 30 SLITESWEDENLABO KADA ABOUCADARMIN.DE INIETTEL DES SOCIETESBP 12375NIAMEYNIGERLAWTON J.CEMBUREAU55 rue d’Arion

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1040 BRUXELLESBELGIUMLEONG G.C.KADAH CEMENT SDN. BHD.31st fl.Menara Dato Onn50480 KUALA LUMPUR LIBERT J.CARRIERES ET FOURS A CHAUXAv. Rogier 214000 LIEGEBELGIUMLINK GUNTERLA CEMENTO NACIONAL CEM.P.O. Box 4243GuayaquilECUADORSOUTH AMERICALOPEZ ALVARO SISACEMENTOS DIAMANTE S.A.Fabrica del NorteAp.A.1166CUCUTACOLOMBIALOWES T.M.BLUE CIRCLE305 London Road GreenhitheKENT DA9 9JQU.K.MAINEEAST AFRICAN PORTLAND CEMENTP.O. Box 40101NAIROBIKENYAMARTIN D.STURTEVANT MILL CO EUROPE8–10, av. de Saturne1180 BRUXELLESBELGIUMMAYNARD JEAN PIERREGAZ DE FRANCED.E.C.23, rue P.Deiorme75017 PARISFRANCE

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LIBERT JOSEPHCARRIERES ET FOURS A CHAUXAv.Rogier 214000 LIEGEBELGIQUELIVONEN ARTOLOHJA CORPORATION CEMENT FACTORY08700 VIRKKALA FINLANDFINLANDLOPO T.CIMPORRua Alexandre Hercuiano 351200 LISBOAPORTUGALMAHER BADRNATIONAL CEMENT CO5–26 Juky streetP.O. Box 18CAIROEGYPTMAKRIS M.CLECedex 2392290 PARIS LA DEFENSEFRANCEMATEOS Manuel PazHORNOS IBERICOS ALBA S.A.Nunez de Balboa, 35-A28001 MADRIDSPAINMENDES E.L.EFACECRua Rodrigo de Fonseca 76–3°LISBOAPORTUGAL MENDES M.D.G. DE ENERGIAAv. de la Republica, 45–5°1000 LISBOAPORTUGALMETWALLY MOHAMEDHELWAN PORTLAND CEMENT COPO Box 16HELWANEGYPT

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MICHINO T.KAWASAKI HEAVY INDUSTRIES LTDOststrasse 104000 DUSSELDORF 1GERMANYMIELL Pat S.CASTLE CEMENT LTDKetton, NR StamfordLINCS PE9 3SXU.K.MIN UNG CHEESSANGYONG CEMENT INDUSTRIAL COC.P.O. BOX 4106SEOULKOREAMOMMENS HenriCBR CIMENTERIES S.A.Ch. de la Hulpe, 1851170 BRUXELLESBELGIQUEMOSTEFA DELLA AhmedCIMENTERIE D’ECH CHELIFFBP 54ECH CHELIFFALGERIEMERLES.C.A. SOC.DES CIMENTS D’ABIDJANB.P. 3751Bd.PortuaireABIDJANCOTE D’IVOIREMEZAR MAGEDSUEZ CEMENT CO35 Ramses StreetNile Bank BuildingCAIROEGYPTMIEBACH SohnePORTLANDZEMENTWERK WITTEKIND HUUGOPostfach 11064782 ERWITTEGERMANYMIGUENS C.DIRECCAO GERAL DA ENERGIARua da Beneficiencia, 241

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1600 LISBOAPORTUGALMOINE J.CLECedex 2392290 PARIS LA DEFENSEFRANCEMOSES I.AENDEBENUE CEMENT COMPANY LTDP.M.B. 12702LAGOSNIGERIAMUELLER J.JCF-JURA CEMENT FABRIKENAarau Wildegg5103 WILDEGGSWITZERLAND MURTRA IsidoroLA AUXILIAR DE LA CONSTRUCCION S.A.Av. Diagonal 53408006 BARCELONASPAINNALACACI H.ADANA CIMENTO SANAYII T.S.A.Ceyhan Yolu Uzeri 12KmADANATURKEYNETO S.CIMPORCentro de Producao de Alhandra2600 VILA FRANCA DE XIRAPORTUGALNIELSEN Knud FrilsF.L.Smidth & Co. A/SVigersiev Allé 772500 ValbyDENMARKNISSEN TorbenF.L.Smidth & Co. A/SVigersiev Allé 772500 ValbyDENMARKNYAGBA I.SolomonBENUE CEMENT COMPANY LTDP.M.B. 12702

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LAGOSNIGERIAOGAWAEURANTICApartado 772766 ESTORIL CODEXPORTUGALNAGEH GAMALHELWAN PORTLAND CEMENT COPO Box 16HELWANEGYPTNETO J.M.CIMPORCentro de Producao de Souselas3000 COIMBRAPORTUGALNICOU P.49/51 S.Venizelou st.14123 LYCOVRISSI ATHENSGREECENINA MarioINST.SUP.TECH. DEPT.ENGEN.MECANICAAv.Rovisco Pais1000 LISBOAPORTUGALNOHLMANS T.NOVEM B.V.P.Box 176130 AA SITTARDNETHERLANDSO KYU KWONTONG YANG CEMENT CORP.114 Sajik Dong Samcheok CityKANGWON DOKOREAOLIVEIRA M.CIMPORRua Alexandre Hercuiano 351200 LISBOAPORTUGAL OLLER OSVALDOCEMENTOS NACIONALES S.A.Apartado 14Caretera Neila Km 10

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SAN PEDRO DE MACORISDOMINICAN REPUBLICOSMAN JobSOCOCIMCimenterie du RufisqueB.P. 39 RufisqueSENEGALPALAHI Juan Luis AbelianTAKUMA Co.Ltd.3–23 Dojima Hama l-ChomeKITA-KU OSAKA 530JAPANPALOMAR P.CEMENTO HORMIGONCalie Maignon 2608024 BARCELONASPAINPARISSI FRANCESCOIMPIANTI CEMENTIR S.P.A.Via Le Gorizia, 24/D00198 ROMAITALYPECH MICHELVICAT TOUR GANCedea 1392082 PARIS LA DEFENSEFRANCEPERALES MARIOCEMENTOS CARIBE C.A.Puerto CumareboEstado FalcanApartado 7416VENEZUELAORTOLANI V.ITALCEMENTIVia G.Camozzi, 12424100 BERGAMOITALYPAIS S.ELECTRICIDADE DE PORTUGAL E.P. EDPAv. José Malhoa, lote A-131000 LISBOAPORTUGALPALIARD M.CLE TOUR TECHNIP

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170, place Henri RegnaultCEDEX 23 922090 PARIS LA DEFENSEFRANCEPARISAKIS G.UNIVERSITY OF ATHENS28 October st. 42ATHENASGREECEPARKES P.P.CASTLE CEMENTClitheroe LanesBB7 4QFU.K.PENA Angel LongareiaCEMENTOS COSMOS S.A.Luchana, 23, 4°28010 MADRIDSPAINPEREIRA A.D.G. INDUSTRIAAv. Cons.Fernando Sousa, 111000 LISBOAPORTUGAL PEREIRA M.C.CENTRO PARA A CONSERVACAO ENERGIARua S.Domingos à Lapa 117–2°1200 LISBOAPORTUGALPETRES RogerioCIMENTO CAUE S.A.Rod.MG 424, km 18-P.LeopoidoCaixa Postal 40 CEP: 33.600BRASILPIMENTEL M.CEEETA INST.SUP.ECONOMIARua Miguel Lupi 201200 LISBOAPORTUGALPITA G.INST.SUP.TECNICOAv. Rovisco Pais1096 LISBOAPORTUGALPLAZA F.CIMPOR

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Centro de Producao de Alhandra2600 VILA FRANCA DE XIRAPORTUGALPOPEK J.C.FIVES CAIL BABCOCKLILLEFRANCERAMZY HOUSE INSUEZ CEMENT CO35 Ramses streetNile Bank BuildingCAIROEGYPTPESENTI G.ITALCEMENTIVia G.Camozzi, 12424100 BERGAMOITALYPILCHMAIERNORICUM MASCHINENBAU UND HANDELPostfach 34010 LINZAUSTRIAPINHO J.S.SOFOMILCalçada Paima de Baixo 10-B1507 LISBOA CODEXPORTUGALPLATSCHORRE M.I.ENCISt Teunislaan, 15231 BS S-HERTOGENBOSCHNETHERLANDSPONA A.P.ASEA BROWN BOVERIAv.Cons.Fernando Sousa 25-B1000 LISBOAPORTUGALQUIRKE D.CEMBUREAU55 rue d’Arlon1040 BRUXELLESBELGIUMREVILLE D.CEMBUREAU

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55 rue d’Arlon1040 BRUXELLESBELGIUM RICHTER G.Christian PfeifferPostfach 1763Sudhofferweg 110/1124720 BECKUMGERMANYROBERTO Maria da PiedadeRua da Beneficencia, 2411600 LISBOAPORTUGALRODRIGUEZ Jesus MartinezCEMENTOS COSMOS27392—OURAL (LUGO)SPAINROSARIO M.CIMPORRua Alexandre Hercuiano 351200 LISBOAPORTUGALRUANGWIT J.JALAPRATHAN CEMENT CO1 Jalaprathan Cement RoaédTAKLI NAKORNSAWAN 60140THAILANDRYU S.C.SSANGYONG2-GAJeo-Dong Jung-GuSEOUL 100–748KOREASAMOUILHAN E.CLECedex 2392290 PARIS LA DEFENSEFRANCERITO H.CIMPORRua Alexandre Herculano 351200 LISBOAPORTUGALRODRIGUES HELDERAVo Fernao de Magalhaes 34

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20 Andar MaputoMOZAMBIQUEROMAO R.CIMPORRua Alexandre Herculano 351200 LISBOAPORTUGALROTHER W.KRUPP POLYSIUS AGP.O. BOX 23404720 BECKUMGERMANYRUSHDY AHMEDALEXANDRIA PORTLAND CEMENT COP.OB. El MexALEXANDRIAEGYPTSALEM DIR.NATIONAL CEMENT CO5–26 July streetP.O. Box 18CAIROEGYPTSANG Hyuck24–1 2 Ka Jedo DongChoong-KuSEOUL PO BOX 4106KOREA SANTOS F.CIMPORCentro Producao Cabo Mondego2080 FIGUEIRA DA FOZPORTUGALSANTOS M.CIMPORCentre Producao Cabo Montego3080 FIGUEIRA DA FOZPORTUGALSAULI Raffaeie S.C.A.C.C.I. S.P.A.Via G.B. De Rossi, 2200161 ROMAITALYSCHEUER A.VDZ

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Tannenstrasse 24000 DUSSELDORF 30GERMANYSCHNEBERGECIMENTS DU ZAIRE30, Bd du 30 Juin-Building CCIB.P.7598KINSCHASAZAIRESEQUEIRA A.COMETNARua Academia das Ciencas 51200 LISBOAPORTUGALSEVELSOCIETE DES CIMENTS FRANCAISLes technodes78931 GUERVILLE CEDEXFRANCESANTOS G.SECRETARIA DE ESTADO DE ENERGIARua Horta Seca 151200 LISBOAPORTUGALSARAIVA J.CIMPORRua Alexandre Hercuiano 351200 LISBOAPORTUGALSCANTLEBURY ANTHONYARAWAK CEMENT COMPANYChecher HallSt LucyBARBADOSCENTRAL AMERICASCHMIDT MANFREDO&K anlagen systeme g.a4722 ENNIGERLOHGERMANYSEONG SOO KIMSSANGYONG/CEMENT IND.COSsangyong Bld., 24–1 2GA Jeo DongJung-GuSEOUL 100–748KOREA

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SEQUEIRA J.AUDITERGRua Edison 3-r/c-E1000 LISBOAPORTUGALSHALABY SaiHELWAN PORTLAND CEMENT COP.O. BOX 16HELWANEGYPT SHIM YONG JINHANIL CEMENT MFG.CO832–2 YouksamdongKangnam KuSEOULKOREASHUTLER Michael V.ASEA BROWN BOVERI LTDHasseistrasse5401 BADENSUISSESILVA R.SECRETARIO DE ESTADO DA ENERGIARua da Horta Seca 151200 LISBOAPORTUGALSING LEE CHOON17, Pioneer Crescent, Jurong TownSINGAPORE 2262SINGAPORESOARES Jarbas FernandesCIMENTO CAUE S.A.Rod.MG 424, km 18-P.LeopoidoCalxa Postal 40 CEP.: 33.600BRASILSORNIN B.CLECedex 2392290 PARIS LA DEFENSEFRANCESOUSA J.CIMPORCentro Producao de Souseias3000 COIMBRAPORTUGAL

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SHIRANE M.TAKUMA CO.LTDEitaro Block-2–5 Nihon Bashi1 CHOME CHUO KU TOKYOJAPANSIMAO V.LNETIRua S.Pedro de Alcantara 791200 LISBOAPORTUGALSILVA O.CIMPORCentre Producao de Louie8101 LOULE CODEXPORTUGALSIRCHIS J.CCE200 rue de la Lo1049 BRUXELLESBELGIUMSODERSTROM StenBox 1762030 SLITESWEDENSOUSA H.LNETIAz.Lameiros Estrada Paço Lumi1600 LISBOAPORTUGALSTEINBISS E.KHDPostfach 9104045000 KOLN 91GERMANY SYAIFUL IR.PT.SEMEN PADANGPO BOX 94PADANG 25237INDONESIATAKAKUSAKI H.NCC OHTEMACHI BLDG6–1 1-Chone Ohtemachi ChiyoTOKYOJAPANTAVERAS ANDRES SANTOS

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CEMENTOS CIBAO,C FOR AApartado Palo AmarilloSANTIAGODOMINICAN REPUBLICTOMAZ I.CIMPORRua Alexandre Herculano 351200 LISBOAPORTUGALTORRES A.ASLANDOrense 8128029 MADRIDSPAINVALLE J.G.ASLANDOrense 8128020 MADRIDSPAINVERGARA ROLANDO ARIZACOMPANIA COLOMBANIA DE CLINCER S.AApartado Aereo 3344CARTAGANACOLOMBIASOUTH AMERICATAE KYUN LEEASIA CEMENT MFG CO120–23 Seosomoon-DongChung-KuSEOULKOREATANGNEY SeanIRISH CEMENT LTDStillorgan RoadSTILLORGAN.CO.DUBLINIRELANDTELFORD R.IRDAC200 rue de la Loi1049 BRUXELLESBELGIUMTORRE Manuel AizpuruCEMENTOS LEMONA S.A.Alda.de Urquijo, n°10–2°48008 BILBAO (BIZKAIA)

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SPAINTRAKIDISTITAN CEMENT COMPANY S.A.8, Dragatsaniou street10559 ATHENSGREECEVASCONCELOS I.DIRECCAO GERAL QUALIDADE AMBIENTEPORTOPORTUGALVIAUD MICHEL PERALTACEMENTO DE EL SALVADOR S.A.P.O. Box (05) 17SAN SALVADOREL SALVADORCENTRAL AMERICA VILLAR J.R.M.FABRICIA DOMINICANA DE CEMENTOApartado Postal 1335SANTO DOMONGODOMINICAN REPUBLICWEINERT K.H.INTERATOMPostfach, Friedrich Fbert strasse5060 BERGISH GLADBACH 1GERMANYWERNER B.ASEA BROWN BOVERI LTDHasseistrasse5401 BADENSUISSEZIEGENFUSS JochenWIETERSDORFER & PEGGAUERWietersdorf9373 KLEIN ST PAULAUSTRIAVIRTUTO JR. FR.HI CEMENT CORPORATIONKal.Buil.164 Salcedo streetLEGASPI VILLAGE, MAKATIPHILIPPINESWEIT H.Christian PfeifferPostfach 1763Sudhofferweg 11/112

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4720 BECKUMGERMANYYUS FF OMARtrinidad cement ltdSouthern Main RoadClaxton BayIRINIDADSOUTH AMERICAZOUBOV N.STURTEVANT MILL Co EUROPE8–10, av.de Saturne1180 BRUXELLESBELGIQUE

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INDEX OF AUTHORS

AELLEN, F, 155AHLKVIST, B, 73

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

DUMAS, J, 109

GARCIA DEL VALLE, J, 36

KINDERMANN, F, 3

LOWES, T M, 137

MAKRIS, M, 129MENARDI, G, 129

NAKAJIMA, Y, 48NETO, M, 145

PALIARD, M, 129PARISAKIS, G, 155

PARKES, P F, 88

QUIRKE, D, 161

RIBEIRO DA SILVA, N, 8

SCHEUER, A, 27SIRCHIS, J, 155SOARES GOMES, A., 23SPRUNG, S, 27STEINBISS, E, 57, 155

TAKAKUSAKI, H, 155TORRES, A, 36

WEINERT, K-H, 82

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