energy efficiency in the cement industry

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

ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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

ENERGY EFFICIENCY IN THE

CEMENT INDUSTRY

Edited by

J.SIRCHIS

Directorate-General for Energy,

Commission of the European Communities,

Brussels, Belgium

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Energy efficiency in the cement industry.

1 European Community countries Industries Energy.

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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

OPENING SESSION

Chairman: V Teixeira Lopo, President CIMPOR

OPENING ADDRESS—ENERGY POLICY OF THE COMMISSION OF THE EUROPEAN

COMMUNITIES

F KINDERMANN, Commission of the European Communities

2

OPENING SPEECH—A POLICY OF ENERGY EFFICIENCY

NUNO RIBEIRO DA SILVA, Secretary of State for Energy

6

FIRST SESSION

Chairman: Professor Veiga Simao, President of LNETI

ENERGY SAVING AND ENVIRONMENTAL IMPACT IN THE CEMENT INDUSTRY

A SOARES GOMES, CIMPOR, Cimentes de Portugal, Portugal

16

ENERGY OUTLOOK IN WEST GERMANY’S CEMENT INDUSTRY

A SCHEUER and S SPRUNG, Forschungsinstitut der Zementindustrie, Düsseldorf 30, Federal

Republic of Germany

20

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

JESUS GARCIA DEL VALLE and ALEJANDRO TORRES Asland Tecnologia SA, Madrid,

Spain

29

ENERGY OUTLOOK IN THE JAPANESE CEMENT INDUSTRY

YUKIO NAKAJIMA, Nihon Cement Co Ltd., Tokyo, Japan

42

SECOND SESSION—PART 1—SPECIFIC TECHNOLOGIES AND CEC DEMONSTRATION PROJECTS

Chairman: J Sirchis, Commission of the European Communities

TRADITIONAL AND ADVANCED CONCEPTS OF WASTE HEAT RECOVERY IN

CEMENT PLANTS

E STEINBISS, KHD Humboldt Wedag AG, Cologne, Federal Republic of Germany

52

BO AHLKVIST, Cementa AB, Sweden

HEAT RECOVERY ON THE SMOKE OF THE CEMENT KILN AND UTILIZATION OF THERECOVERED ENERGY

J-F BOUQUELLE, Département Projets Ciments d’Obourg, Obourg, Belgium

69

UTILIZATION OF WASTE HEAT FROM THE CEMENT ROTARY KILN

K-H WEINERT, Interatom GmbH, Bergisch Gladbach, Federal Republic of Germany

74

ENERGY SAVING BY UTILISATION OF HIGH EFFICIENCY CLASSIFIER FOR

GRINDING AND COOLING OF CEMENT ON TWO MILLS AT CASTLE CEMENT

(RIBBLESDALE) LIMITED, CLITHEROE, LANCASHIRE, UK

P F PARKES, Castle Cement, Clitheroe, United Kingdom

81

SECOND SESSION—PART 2—ENGINEERING AND ENERGY MANAGEMENT

‘HOLDERBANK’S’ ENERGY MANAGEMENT IN THE 1990s

M BLANCK, ‘Holderbank’ Management and Consulting Ltd, Holderbank, Switzerland

90

ENGINEERING AND ENERGY SAVINGS

J DUMAS, CITEC, Guerville, France

102

ENERGY SAVINGS IN CEMENT KILN SYSTEMS

E BIRCH, F L Smidth and Co AS, Valby, Denmark

112

HIGH ENERGY SAVINGS THROUGH THE USE OF A NEW HIGH-PERFORMANCE

HYDRAULIC COMPONENT THE K-TECH PROCESS

M PALIARD and M MAKRIS, CLE, Paris La Defense, France G MENARDI and M BAILLY,

Ciments de Champagnole, Dole, France

125

ENERGY MANAGEMENT IN THE UK CEMENT INDUSTRY

T M LOWES and K W BEZANT, Blue Circle Industries plc, Greenhithe, Kent, United Kingdom

136

WASTE GAS HEAT RECOVERY IN CEMENT PLANTS

M NETO, Souselas Cement Plant, CIMPOR, Portugal

144

THIRD SESSION—RODND TABLE DISCUSSION

Chairman: Professor Mario Nina, University of Lisbon K W Bezant, BLUE CIRCLE, United

Kingdom F Aellen, HOLDERBANK, Switzerland Professor G Parisakis, University of Athens, Greece

J Sirchis, Commission of the European Communities E Steinbiss, KHD, BR Deutschland H

Takakusaki, NIHON CEMENT CO, Japan

LIST OF PARTICIPANTS

viii

160

OPENING SESSION

Chairman: V Teixeira Lopo, President CIMPOR

OPENING ADDRESS

“ENERGY POLICY OF THE COMMISSION OF THE EUROPEAN

COMMUNITIES”

F.KINDERMANN Head of Division Commission of the European Communities Directorate-General for Energy Technology Directorate Programme Management: Solid Fuels and Energy Saving

If one goes back to the roots of the European Community, one discovers that two of the three Treaties deal,partly of completely, with energy

– The Treaty establishing the EUROPEAN COAL AND STEEL COMMUNITY (ECSC) was signed in Paris

In 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 coordinated

on the European level It was only under the influence of the 1973 shock that quantified targets for selected,energy carriers in the Community were defined Of course, the main concern was, at that time, to 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

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 addition

to 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 after

1992 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 initiatives

in this field have been launched since the beginning of 1989 These include new schemes for greater 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

cross-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 fewyears 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

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

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:

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 beginning

of next year

4 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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

A POLICY OF ENERGY EFFICIENCY SPEECH OF HIS EXCELLENCY THE SECRETARY OF STATE FOR

ENERGY

NUNO RIBEIRO DA SILVA

The aim of the Common Energy Policy in Portugal for the period up to 1995 is a 20% saving 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 competitiveness

of 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 mostimportant components of a logical use of energy in the widest sense:

– the management of energy at the level of the company or the region;

– 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 andtransformation

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 theprjects, 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 use

of energy:

– Increase in production and quality of equipment, systems and energy services;

– Development of decentralised means of electrical energy production with a resultant drop in the costsand 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 contractualconditions of supply of energy to the public network:

– Increase in the viability, through financial support of energy projects, which may otherwise be of onlyminor 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 energy

2 The Community programme VALOREN

3 The Community programme of pilot studies in the field of energy

4 PEDIP

II) REGULATORY INSTRUMENTS

1 Regulation of independant production of electrical energy

2 Regulation on the management of energy consumption

3 Regulation on the thermal characteristics of buildings

A POLICY OF ENERGY EFFICIENCY 7

III) SYSTEM OF ALTERNATIVE FINANCING

– Financing by third parties

I would like to take advantage of the present occasion, albeit in a necessary summary fashion, to take stock

of the situation regarding these instruments in the two years of a coherent energy policy which has gonehand in hand with a community policy for this sector

1

SIURE incentive system for the rational use of energyThis 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 & Doperations—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 Communityprogramme 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 oldsystems, as indeed has the number of applications, already up to 217, as compared with 245 in the two years

of SEURE

The 82 operations approved in the three phases already completed is more than those of SEURE (75);moreover approvals represent 66% acceptance of the projects proposed, whereas in SEURE the rate was 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

8 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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 cannot

be 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 PROGRAMMEThis 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 3applications which have already been processed

This sum corresponds to approximately 79% of the subsidies provided by SIURE and up to 26% of fundsavailable 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 aview to attracting more applications

The commitments undertaken in participation in energy projects relating to the public or comparableinfrastructures 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

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 PROJECTSThis 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 to

a survey conducted by the Ministry of Energy and industry This is by no means by chance

Since 1986, the date of the our accession to the Community, we have participated—in the sense that thePortuguese entrepreneurs, in conjonction with Universities or national laboratories have made applications

to the programme

Since great care always been given to the choice and preparation of good projects, the percentage 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

10 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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 General

of 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, it

is essential that the interested parties cleraly justify their technical and economic aims; that there should be

no other intentions for the same site; and that different uses are not being considered for the same 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

A POLICY OF ENERGY EFFICIENCY 11

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 fundamental

to 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 After

5 years of use, these 33 will bring out an annual saving of at least 30,000 tons equivalent of oil, i.e Esc.675m in foreign exchange

The approach of the Secretary of State is not bound by the mere wording of the regulations It is rather 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

12 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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 furtherstudies 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 BUILDINGSThis 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 theaim 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 residentialbuildings 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 PARTIESThe 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

A POLICY OF ENERGY EFFICIENCY 13

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

14 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

FIRST SESSION

Chairman: Professor Veiga Simao, President of LNETI

ENERGY SAVING AND ENVIRONMENTAL IMPACT IN

THE CEMENT INDUSTRY

ANGELO SCARES GOMES CIMPOR, Cimentos de Portugal, Portugal

Summary

Since 1986 CIMPOR’s Maceira cement plant has had a tyre burning installation workingregularly 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

INTRODUCTIONThe 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

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 PLANTThe 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:

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

ENERGY SAVING AND ENVIRONMENTAL IMPACT 17

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 OUTLOOKDuring 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 output ton Thermalconsumption

kcal/kg

×1000 Esc

(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 in

1984, and did not allow recovery of the investment

What is the reason for such a drastic reduction of profit? It is basically due to the following factors.– The significant reduction of the quantity of tyres burned each year compared to the expected level.Instead of 7500 to 8000 tons per year, or even 15000 tons if tyres were burned in both kilns, the factoryburned only 5848 tons, due to lack of supply of tyres

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

18 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

– 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 COLLECTINGThe 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 well

as 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

ENERGY SAVING AND ENVIRONMENTAL IMPACT 19

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT

INDUSTRY

A.SCHEUER and S.SPRUNG Forschungs institut der Zementindustrie, Tannenstraße 2, 4000 Düsseldorf 30 Federal Republic of Germany

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 in

1988 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 design

of electrical drives as well as a sophisticated energy management

1

INTRODUCTIONThe manufacture of cement is very energy-intensive Already in the past great efforts have therefore been made

to lower the energy consumption in the manufacture of cement (1) By using advanced rotary kilns andshutting down older kilns the fuel consumption fell for instance from 4.8 GJ/t of cement in 1960 to 3.0 GJ/t

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).

The most important process stages where energy savings are constantly sought are

a) the preparation (combined drying and milling) of the raw material components,

b) the burning of the kiln feed to cement clinker and

c) the preparation (milling) of the clinker to cement

Under the headings

a) energy savings through product innovation

b) energy savings through process optimization and

c) energy savings through waste heat utilization are discussed the possibilities the German cementindustry 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 INNOVATIONPortland 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 types

of 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 2

shows 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

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY 21

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 borne

in 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.

ENERGY SAVINGS THROUGH PROCESS OPTIMIZATION

Fuel energy savingsThe 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 or

B 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

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

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 coolerSince all rotary kilns in the Federal Republic of Germany are fed with fuel via silos or tanks, the percentage

of primary air in the total combustion air is normally smaller than 10 % Measures to improve heat recovery

in the clinker cooler therefore aim at a further drop in the primary air proportion to about 5 % with at 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 may

be further improved by a higher clinker bed in the recuperation zone, e.g by narrowing the grate width or

by lowering the number of thrusts Furthermore, heat transfer may also be improved by grate plates 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

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY 23

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 kilnEspecially 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 dependence

on 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

PreheaterThe 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 may

be 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 kilns with and without tertiary air duct

24 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

Savings in electrical energyThe 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.

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

ENERGY OUTLOOK IN WEST-GERMANY’S CEMENT INDUSTRY 25

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-pressuregrinding 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 would

be 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.

26 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

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 preheatersBetween 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 of

350 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

OUTLOOKAdvanced 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

(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 Verein Deutscher Zementwerke, Düsseldorf 1987.

28 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY

JESUS GARCIA DEL VALLE AND ALEJANDRO TORRES

ASLAND TECNOLOGIA, S.A.

P de la Castellana, 184, 7

28046 Madrid, SPAIN

Summary

The poor economic performance of Latin America during the last decade and the high level

of debt is restraining the development The Cement Industry Outlook in Latin America 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 ENVIRONMENTUncertainty 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

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

GROSS DOMESTIC PRODUCT GROWTH

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 toincremental production as high as 11

5 The protection barriers set up by the industrial countries These barriers are costing Latin Americamore 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 seriouslyrestraining their development:

30 ENERGY EFFICIENCY IN THE CEMENT INDUSTRY

GROSS DOMESTIC PRODUCT GROWTH

LAST DECADE YEARLY AVERAGE

OUTLOOK OF LATIN AMERICAN CEMENT INDUSTRY 31