guide nox anglais - ademe

The French Cement Industry Guideto

NOx Emissions Reduction Measures

1. NOx Emissions p. 22. Regulation p. 23. Objectives p. 34. Reference Data p. 45. Primary Measures p. 66. Secondary Measures p. 107. Costs Balance p. 118. Conclusions p. 14

Appendix 1: evolution of the regulation p. 16Synthetic Projects Sheets p. 18

A Convention between ADEME(French Agency for Environment and Energy Management)

& the CEMENT INDUSTRYunder the aegis of MEDD

(Ecology and Sustainable Development Ministry)

16 decembre 2002

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AC.245R–16 decembre 2002

The French Cement Industry Guide toNOx Emissions Reduction Measures

Five companies form the French cement industry, running 33 cement plants witha total production of 20 millions tonnes of cement in 2001 and 5230 employees.Cement consumption in France has been decreasing since the middle of the 70s:there were 25 millions tonnes produced in 1990.

1. NOx Emissions

In 1990, the French cement industry NOx emissions (NO et NO2) were of40 770 tonnes, and of 29 760 tonnes in 2000. NOx formation in cement plants is 95 %nitrogen monoxide ; NO2 formation occurs at low temperatures in contact with the air inthe atmosphere.Total French NOx emissions in 2000 were of 1 905 000 tonnes. Cement plants accountfor 1,56 % of national emissions, while total industrial NOx emissions account for about11 %.The cement industry is a significant industrial contributor with a manufacturing processwhich requires a flame around 2000 °C in order to bring about the necessary chemicalcombinations.Current French cement industry NOx emissions average out at about 1,8 kg/t ofmanufactured clinker.

2. Regulation

Nitrogen oxides are the subject of sustained attention at the European level (seeappendix 1). The European Directive of 4 December 2000 transposed in the20 September 2002 decree on Waste incineration and co-incineration, has set limitvalues of 800 mg/Nm3 for existing cement plants and of 500 mg/Nm3 for future cementplants. Emission values for wet-process kilns, or those burning waste below 3 t/h cango as far as 1200 mg/Nm3 until 1st January 2008.

From 1999 to 2010, France will also have to reduce its NOx emissions by about 47 %,within the framework of the National Emission Ceilings Directive and of the GenevaConvention.

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The European directive on Integrated pollution prevention and control (IPPC) has alsopresented the Best Available Technology (BAT) concept, developed in view of cementplants application.

3. Objectives

The relative inexperience of France in this domain has led the cement industry to setup a tests program in 1999, through the impetus of both National Planning &Environment Ministry and ADEME, in order to dispel the last remaining uncertainties(industrial feasibility, performances, costs,…) over a number of practical difficulties in the application of the BAT Working Group conclusions, or concerning certainperformance levels, possible cross-effects or the application of certain technologies onthe cement process.

This program comprises fifteen different projects, with 1,77 M Euros financed byADEME on a 6,34 M Euros planning budget, through a convention signed jointly withATILH and the cement companies.

The present document presents the industrial feedback on those technologicaloptions referenced in the cement industry’s BREF (Best available technologyREFerence document) and is to be circulated as widely as possible amongst allthose concerned: the cement industry, inspection authorities & personnel incharge of classified facilities, etc.….

The test projects can be divided into two main groups:

- primary measures, which aim to reduce NOx formation in the cement kilns orduring the process (staged combustion),

- secondary measures, which aim to destroy the ensuing pollutants at thefacilities output, by chemical means (SCR, selective catalytic reduction orSNCR, selective non-catalytic reduction).

An SO2 emission reduction test was also performed in a cement plant.

Outside this convention, contacts with other countries, Germany and Switzerland inparticular, have shown that treatments belonging to the primary option were the morewidespread, whereas secondary option equipment are usually set in place only to allowsupplementary emission reductions as and when required by kiln operations. Germanyhas 25 % of its kilns set up with secondary treatment equipment, this when regulatorycompliance requires NOx content to remain below 800 mg/Nm3.

Of course, these elements tend to favour primary option measures, even if, at firstglance, these measures don’t seem to be able to deliver levels as low as those reached by the secondary option measures.This options guide provides the technological elements necessary to help operatorsreduce their NOx emissions (expressed as NO2 equivalents) below 800 mg/Nm3 beforethe end of December 20051 for existing facilities, and also gives out prospects forattaining even lower values in compliance with the IPPC and National EmissionCeilings Directives looming on the 2007–2010 horizon, which also concern SO2.

1 Value expressed as a daily average value, at 10% O2, dry gas, 273K, 101,3 kPa

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4. Reference Data

The NOx measurements were realised on-line on all installations. The measures wereintegrated and their means calculated so as to obtain a daily average2.

4.1. Histogram of Daily Averages of on-line measures in 1999, 2000 and 2001:

NOx Emissions - (1999, 2000, 2001 and 2002) for all companiesHistogram of the Daily Averages of On-line Measurements

Number of values for 1999 = 7953, for 2000 = 8116, for 2001 = 8990, for 2002 = 9855

616 87

9

1310

1682

958

692

151

165

1016

1572

2189

875

522

12725

9

1518

2175

1589

756

347

62

231

1620

2659

2504

1464

812

481

84

1665

1650

2284

0

500

1000

1500

2000

2500

3000

0-200 200-400 400-600 600-800 800-1000 1000-1200 1200-1500 >1500(Dry gas at 11 % O2) mg/Nm3

Nu

mb

ero

fd

.a. 1999

2000

2001

2002

This histogram centers around 666 mg/Nm3 in 2001 with 1,9 % of the results greaterthan 1 500 mg/Nm3 in 1999, 1,6 % in 2000 and 0,7 % in 2001, and with markedprogress on the higher values.

4.2. Precision Assessment

Uncertainty of instant NOx measurement3 is estimated at a maximum of 18 % byINERIS (French national institute of industrial environment and risks, under supervisionof ad hoc Ministry). European directive concerning Hazardous waste incineration andco-incineration admits subtracting from each measured value the confidence interval of95 %. This confidence interval must not, however, go beyond 20 % of those limitemission values set down for nitrogen oxides in the directive. Applying the statisticaltechnique of variograms on the daily averages of each kiln in 2000, the cement industryhas computed the experimental uncertainty for the year, taking analytic and samplinguncertainties into account: on average, uncertainty comes out at 23 %, with variationfrom 13 % to 37 % depending on the kilns and their operating conditions. It must bepointed out that variograms computations are particularly sensitive to data instability,which could account in part for the differences in precision.

This level of precision implies that the test results for which incidence of NOx emissionscan be considered as belonging to the same order of magnitude than that of the 95 %confidence interval on the measure itself should be assessed with some caution.

2 the NOx reporting methodology is described in the ATILH document of 24/05/023 or confidence interval at 95 %

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That is particularly the case for some primary measurements, so that we must remainquite careful in assessing the resulting data, not on a qualitative level, but on theirpotential for emission reduction.

4.3. Results Analysis

Nonetheless several elements are interesting: in 1999, which can be used as areference year before the reduction and monitoring tests, we note that most of the616 measures in the 0-200 class corresponded to data-collecting system or kilnoperating system breakdowns. Both have all but disappeared in 2000. In 2001, thereare fewer measures in the over-800 mg/Nm3 classes than in 2000, which were alreadyfewer than in 1999. Again, almost all measures in the under-800 mg/Nm3 classes aremore numerous in 2001 than in 2000 or 1999. This indicates that, following emissionmonitoring set-up, the greater awareness of personnel and probable instructionsmodifications have resulted in a small but definite progress. Results average has thuscome down from 743 mg/Nm3 in 1999 to 738 mg/Nm3 in 2000 and again 666 mg/Nm3

in 2001.

4.3.1.Effect of Process Type

Another important thing to keep in mind is that these histograms are made out ofelementary measures collected from all the cement kilns by ATILH. They follow analmost normal law which shows no differenciation between manufacturing processes orNOx formation #location, so that no process can be singled out as provoking moreNOx concentration than another. This can be deduced from the fact that we know thatwe have here one wet-process cement plant, which process has demonstrably beenproven as generating markedly more NOx than the others in the United States. NOxreduction potential does vary with the type of process however, and processes whichallow staged combustion give the best results with primary measures.

4.3.2. Effect of Raw Materials

On the other hand, there are important factors in NOx differences with equivalentprocesses (which cannot be detailed here for competitive reasons) such as thecombination of raw material burnability and clinker saturation level4. These are directlyrelated to the quarry which feeds the plant and to the type of cement manufactured ;this is quite obvious in the case of white cement with no iron and thus little flux withwhich to reduce the clinkering process temperature. Those factors cannot be directlycontrolled even though they explain a big part of the differences observed in referencemeasures and test results. The Swiss sector-specific agreement on NOx reduction, forinstance, takes the raw material and production process variabilities of each site intoaccount.

It will probably be rewarding to take another look at those mineralizers which heightenraw material burnability –and which are also mentioned in the BAT document –whenassessing NOx reduction technological and economical costs while complying with themarket’s quality levels.

4 coefficient which defines the ratio of calcium oxide mass present in the feed to that which can effectivelychemically combine with the other three oxides during burning process

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4.3.3. Effect of Cement Types

The French cement market is very distinctive in Europe, as its shares in highly reactivecements (52.5, 52.5R) are very high. This requires producing clinker with a higher levelof saturation, which is harder to burn. So even though this factor is important in theprocess, it seems rather difficult to alter.

4.3.4. Effect of Fuels

The influence of fuel characteristics on NOx emissions was not directly studied in thisprogram.

5. Primary Control Measures

Primary measures are control measures which focus on emission reduction by actingon the combustion process:

optimising firing conditions compatible with raw material characteristicsand clinker quality demands,

curbing excess oxygen, reducing flame temperature, creating a reducing zone.

5.1. Kiln Operation Control

The least expensive system is to include NOx measurements in the kiln operationscontrol instrumentation (sheet n° 3: Altkirch, sheet n° 5: Le Teil, sheet n° 15: Grave dePeille).

Sensor positioning is important. It may seem preferable to measure NOx in the exhaustgas box as reaction time is thus shortened, but NOx can still be generated or reducedby fuels coming in up-stream - when considering the direction of meal flow - from thesensors. These two locations can be complementary depending on the type of process.Setting up the sensor at the exhaust gas allows any NOx increase due to slightoverburning to be efficiently eliminated. A better control of the NOx rate can lead to aslight reduction in excess oxygen and thus to another reduction in NOx emission rates.

The test reported for sheet n° 5 show a NOx reduction from 1200 mg/Nm3 to850 mg/Nm3 merely through instrumentation control. Operating parameters allowingthis were maintained for only a day as a clogging ring was starting to form in the kiln.This plant was using a stable synthetic raw meal and liquid fuels only, favourablefactors for kiln operational stability.

Preliminary tests realised for sheet n° 15 (La Grave de Peille) decreased NOx ratesfrom an average of 1150 mg/Nm3 with 1400-1600 mg/Nm3 peaks to an average900 mg/Nm3 with 1200-1300 mg/Nm3 peaks. This result was obtained through kilnoperating control maintaining the oxygen level at 3-4 % in kiln feed end instead of theprevious 6 %.

Tests for sheet n° 15 show very favourable results when extending oxygen control tothe expert system, with peaks over 900 mg/Nm3 disappearing. This control results in anaverage decrease of 100 mg/Nm3.

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On the other hand, tests done for sheet n° 3 haven’t been able to show measurable differences in NOx emission levels depending on whether expert system is on or off.We think this is due to the length of time since this expert system was set up, whichhas lead, over the years, to an harmonisation of human and expert system controlstrategies.

NOx is not the only parameter to take into account in process control. Chemicalanalysis on a plant where the quarry feed is not very regular allows to anticipate firingrequirements. Continuous chemical analysis of the quarry should limit over-firingperiods, according to a supplier. Tests done in another plants yielded no significantresults.

The debate of expert system vs. human operators remains open, as the performanceof the former is strongly dependent on the levels of parameter complexity, and on theirpossible anticipation through human-operated controls or their possible rapid correctionthrough expert systems. Half the cement kilns in France run without.

A common conclusion is held by all though: taking NOx parameter into account underordinary kiln operating conditions allows significant emission reduction and an almosttotal suppression of overburning emission peaks.

5.2. Low-NOx Burners

These burners (sheet n° 2: La Grave de Peille) give various results depending on theirset-up. If the initial burner runs on a low percentage of primary air, a low NOx burnerwill have a marginal effect. This was the case for the La Grave de Peille plant, wherethe test was not done as the suppliers could not guarantee a gain in comparison withthe existing burner. Setting up this kind of burner in other kilns however, lead to realgains, up to 300 mg/Nm3 NOx when compared to a previous burner from an oldergeneration with 15 % primary air.

Primary air percentage is a key point in NOx control. In very specific cases, primary aircan be altogether eliminated when the fuel is in gaseous form. But this type of fuel isusually not economically sound for a cement plant. In fact, fuels used in cement plantsare those difficult to use in other thermal facilities, particularly solid fuels with difficultignition.

The French cement industry is willing to start research and development projectsconcerning pulverised product transportation and kiln injection. Today, techniques usedfor solid fuel or meat and bone meal (MBM) injection remain simple and require a highpercentage of primary air, which leads to NOx increase. Concerted works on thosesubject should lead to cold air injection reduction, and to a better control of the flamedistance d’accrochagewhile avoiding scorching the burner nozzle, as happened incertain tests

5.3. Flue Gas Recirculation

This technique (sheet n° 1: Gargenville) realises partial or complete primary airsubstitution in the burner, lowering the oxygen level of the fuel in the hottest zones, andtheoretically reducing NOx formation, aiming for reduction levels identical to the lowNOx burner technique. Tests did lead to important reduction rates of 20 % to 30 % butwithout reaching the objectives, and starting from rather high initial levels. Furthermore,performances turned out to be rather uneven.

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This is a difficult technique to implement, as flue gas must have very little oxygen, nodust particles and be at an acceptable temperature for the Roots blower. Flue gasrecirculation also lengthens the kiln flame and increases CO generation. Flue gas arealso incompatible with MBM injections, as they tend to gel, provoking unacceptableinjection irregularities. This process was unsuccessfully tried in Germany, were itbrought about serious operating breakdowns. But on the other hand, it is being appliedwith great success in Italy, on a long granules kiln with an operating history of greatregularity.

A thorough gas treatment to provide very low dust contents, and a constanttemperature are prerequisites for using this technique, obviously efficient when itworks !

Pyrolysis of waste fuels may turn out to be an interesting path to explore, despite acertain complexity in the initial process. NOx reduction potential and the cost per ton ofthus avoided NOx still remain to be determined however.

5.4. Injecting Pure Water or Water with Additives

(sheet n° 6: Gargenville, sheet n° 7: Grave de Peille, sheet n° 8: Val d’Azergues)

5.4.1 Pure Water Injection

Pure water injection also decreases the NOx average by reducing the temperature inthe high temperature zone of the flame ; this mostly eliminates the peaks by simpleflow control.

The injection can be done at different locations and in different forms: PILLARD ZV2burners assist liquid fuel injection with water vaporisation, with good results.

Water can be injected in the flame centre with great efficiency: such was the case insheet n° 6, where 500 to 2000 l/h were injected, resulting in an average reduction of100 mg/Nm3 of NOx with initial emissions at 1000mg/Nm3, but more markedly, adecrease in the standard deviation of measurements from 286 to 126 mg/Nm3, whichquantifies the reduction of emission peaks.

5.4.2 Injection of Water with Additives

In sheet n° 8, injection in the centre of the burner reduced stack emissions from1650 to 1200 mg/Nm3, initial NOx emissions being relatively high. It was also possiblein this particular case to try lateral injection on the flame with a separate injector, withgreatly similar results (1250 mg/Nm3). Injection tests were also done directly in thesecondary air duct, for instance sprayed on the clinker chute, but results were lessconvincing (1400 mg/Nm3).

Water with carbonate additives gives out interesting results: the tests done for sheetn° 6 show similar results in NOx reduction for an injection of water with additives at16 l/tonne of clinker and for pure water injection at 20 l/tonne of clinker. Beyond thedirect effect of water, we can suppose that a staged combustion effect favourable toNOx reduction operates here. A slighter loss in production (1,6% for 10 l/tonne ofclinker) can be observed, when compared with pure water injection.

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This result is confirmed by tests in sheet n° 7, which indicate that 500 l/h of pure waterhas had no influence, whereas 500 l/h of water + 200 l/h of hydrocarbons lead to adecrease of 200 to 300 mg/Nm3 in the 900 mg/Nm3 zone.

5.5. Staged Combustion

Staged combustion is a promising NOx reduction technique and is already operating ina few plants, in California amongst other. The key points of the process are the use offuel to create a reducing zone, that of excess air at kiln feed end and the temperaturein the sintering zone. The specific MINOX test at Port la Nouvelle (sheet n° 9) wasinconclusive because of operational instability in the process. It was possible to obtaina NOx reduction of about 200 mg/Nm3 with initial emissions at 1000 mg/Nm3 zoneduring the test but during too short a period due to process instability. Other similarsystems based on the same principles have also given promising results.

Precalciner kilns allow independent settings of the oxidation/reducing levels in thecement kiln and in the precalciner kiln. Injection of part of the fuel in the exhaust gasbox can then decrease NOx emissions.

Similarly, adding fuel to the grate of LEPOL kilns can lead to a significant NOx reduction,but implies keeping an eye on the evolution of the other air pollutant emissions.

Cyclone preheater kilns without precalciner also allow slight reductive runs wheninjecting fuel in the exhaust gas box, though to a lesser degree. Permanent monitoringof SO2 and VOC levels becomes necessary as they tend to increase because of thelocal reducing zone.

A long kiln with mid-kiln staged combustion has been operating in the Los Angelesarea in the United States for several years now. Even though the data is confidential,results show that the principle is interesting and worth going further into for this type ofprocess.

Staged combustion is the object of collaborative studies in Germany, followed withinterest by the French cement industry, as this technique presents a NOx reductionpotentiality probably very near that of SNCR.

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6. Secondary Control Measures

Secondary measures are those that reduce already formed NOx into N2 and H2Othrough chemical reactions. The two techniques already in use in several industrialsectors - SNCR and SCR - reduce NOx by the action of urea or ammonia. Severalprerequisites concerning temperature, residence time, gas mixture and NH3/NO molarratio must be fulfilled if these selective reactions are to be successful. Very briefly put,reducing temperature ranges for SNCR are in the 850-1050°C range, with a molarration of more than 1, even 2 in certain cases, and in the 250-400°C range for SCRwith a molar ratio around 1 on a catalysts.

6.1. Selective Non-Catalytic Reduction System (SNCR).

There is a clear NOx reduction when injecting urea or ammonia with the stoichiometricratio. This is a very efficient NOx emission reducing system (sheet n° 10: Saint Pierrela Cour, sheet n° 11: Héming, sheet n° 12: Lumbres, sheet n° 13: Cruas). Except in thecase of an injection with a rotating connection on a long wet kiln (sheet n° 12), itbecomes quite possible to respect the 800 mg/Nm3 limit value and even stay wellunder if necessary.

The injection zone varies with the type of kiln process. Injection technique for rotarykilns seems quite applicable to long kilns, but presents serious reliability problems andcan still be improved..

Cost issue aside, SNCR used continuously may also give out smells through NH3 slipsat the stacks, or, mostly, in the fines recycled from the filters. This was also pointed outin Germany where a correlation between NH3 injection and a correspondingconcentration in the fines was established. Optimising process implementation shouldsolve these problems.

Process costs would decrease if the product used came from waste. The use ofrecycled ammonia water from a Kodak plant is an example, other possibilities probablyexist. ADEME could help the French cement industry find alternative product sourcesand take part in costs optimisation.

Installing SNCR technology nevertheless costs about 500 000 to 1 M€, which explains the small number of sites where it is operating, even in countries where the process isdeemed to work.

6.2. Selective Catalytic Reduction System (SCR)

Tests done in laboratories (sheet n° 4: IRMA) show that implementing this techniquestrongly depends on the temperature and the overall dust loading conditions. Tooperate, a catalytic process that can bear the high dust levels usual in the firing zonemust be used (high dust system), or the exhaust gases reheated after dedusting (lowdust system), which would mean additional energy costs and very importantinvestments.

A full scale test of catalysts in a "high dust" system was set up in Solnhofen(sheet n° 4 bis: Solnhofen). ATILH toured this plant at the beginning of October 2002.According to the company, the installation has been operating without any majorhitches for 9 000 hours, after a few operating parameters were adjusted (reheating ofcleaning air, upstream circulation of gases for 20% of time).

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This equipment reduces NOx emissions from 1200 to 800 mg/Nm3 at a stoichiometry of0,6 and a temperature of 300°C, a rather disappointing result that can just as well beobtained through primary measures. The installation seems oversize and airconsumption is such that costs balance for SNCR is negative. Investments atSolnhofen cost 3,5 M€, estimated at 2,5 M€ for a kiln with a 1500 tonnes of clinker per day capacity, to which costs for setting-up and adapting the heat exchanger must beadded. Estimated operating costs are 0,75 €/t clinker for a reduction of 400mg/Nm3,with 0,5 to 1 €/t clinker added for replacing the catalysts, means a total cost of 2100 €/t of reduced NOx and 1,93 €/t clinker. There being no precise and verifiable data to control the results announced, those numbers remain theoretical. The cementindustry’s position is that it is somewhat premature to consider this technique asavailable.

Catalytic systems evolving rather quickly, a technology watch on the subject will be setup at ATILH so as to be able to react rapidly in case the "low dust" process or a bettercharacterization of the Solnhofen test emerge.

6.3. SO2 Reduction

Combustion quality, and more particularly absence of CO in the installation is the firstprimary factor in limiting SO2 volatilization in the kiln.

Secondary measure limitation of SO2 is efficient (from 600 to 300 mg/Nm3) with sodiumbicarbonate (sheet n° 14: Beffes), but this technique is valid only when alkaline contentof raw meal is very low, as sodium bicarbonate injection adds 0,1 % alkalis to theclinker, which may turn out to be undesirable. Injection of pulverized lime or calciumcan still be refined, but coating formation in kiln is a determining point.

Other SO2 reduction techniques, such as using a wet scrubber (one operatinginstallation in Sweden, one in Austria) or a dry scrubber (one operating installation inSwitzerland) on exhaust gases can be set up, but information from the German cementindustry indicates a process cost, that is, for instance, 20 times over that of absorbentadditions to the raw meal in a dry process.

7. Costs Balance

7.1 Estimation of Tests Costs Balance

The table below summarises:capital costs specific to each plant (or estimated) taking already existing

equipment into account,total estimated costs (payback and operating costs) specific to each plant, per

tonne of manufactured clinker and per tonne of reduced NOx,Estimated invested sums are affected with an uncertainty factor corresponding tocalculations done at the preliminary stage of project. Measurement uncertainty mustalso be kept in mind, and the fact that operating an installation can lead to both goodand bad surprises where maintenance costs and consequences for the installation areconcerned.

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25/10/2002 Capital Costs[k]

Total Cost Initial NOxLevel

Effectiveness

Sheet Process Capacity Euros mg/Nm3 mg/Nm3

Plant Site [a] Testing t clinker/day

€ per tonne of clinker

€ per tonne of NOx [c] [c]

1 Gargenville DP Flue gasrecirculation

1 340 300.000 0,17 282 1.010 -200

2 Grave de Peille DP Low NOx burner[d]

3 100 455.000[b]

0,07[b]

1.260 -

- - - 5303 Altkirch PrC Expert system 1 200 peaks cut off

4 IRMA Lab SCR[d]

3 600 8.200.000 3,60 2 200 - 80%in laboratory

4bis Solnhofen DP SCR 1 500 2.500.000 1,93 2.100 1.200 -400

[e] [g]

60.000 1.2105 Le Teil alum. Expert system 150[b]

0,20 226 -250

6 1.015Gargenville DP Injection of waterwith additives

1 340 10.000 0,06 184 - 100peaks cut off

7 1.200Grave de Peille DP Injection of waterwith additives

3 100 116.000[n]

0,19 583 -250

600.000 0,23 418 1.300 -3008 Val d'Azergues SDP Injection ofaqueous waste

1 400

[h] [h] [h]

1.500.000 0,28 1.060 -2009 Port la Nouvelle PrC Stagedcombustion[f]

2 200

[m]

-

[f]

10 St Pierre laCour

PrC SNCR 4 000 1.130.000 0,71 478 1.200 -700

11 Héming SDP SNCR 1 200 510.000 0,84 820 880 -300[i]

12 Lumbres WP SNCR [f] 700 551.500 Not pertinent 900 20 - 70 %[ f]

13 600.000 1.210Cruas DP SNCR 570 1,76 622 -400[i]

15 59.000 950Grave de Peille DP Expert system 3 100 0,01 67 - 100peaks cut off

14 Beffes SDP SO2 reductionraw meal

1750 214.5000,12 146

670 -300

lime 0,55 943

[a]: DP: dry process [b]: gross industrial costs including productive investments

SDP: semi-dry process [c]: at 10 % O2 ,dry gas, or in %

WP: wet process [d]: there where no industrial full-scale tests and costs are estimated

alum.: calcium aluminate cement process [e]: not part of the ADEME convention: information provided by VDZ

PrC: precalciner [ f]: non viable reduction technique in the industrial operating conditions of the test

[g]: at a stoichiometry of 0,6

[h]: data provided by Lafarge Ciments (cf. sheet for assessment context)

[i]: the certified bodies have reported better periodic measurement results

[k]: sums correspond to effective realisation or estimations, as the case may be

[m]: estimated from 1000 to 1500 k€ and the higher value used for costs calculations

[n]: payback period of 5 years instead of 10 years as for the other capital investments

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7.2 Costs Instances (in Euro/tonne of NOx) from Other Industrial Sectors

The economical aspect of any environmental technology is of major importance for itsmarket prospects.To be accepted as Best Available Technique (BAT), a technique must be both efficient(important emission reduction) and performing (not too costly and no undesirable side-effects). Costs is probably where the greatest stakes are involved. Severaluncertainties remain, on the level of investments required (up-scaling from prototype toindustrial installation, gross capital assessment, adapting existing equipment) as wellas on the operating costs. Nonetheless, the following estimations can be of help whenplanning middle or long term policies.As quite a lot of cost figures were given at the NOXCONF 2001 congress, it seemsreasonable to think they were of sufficient quality to be accepted as indicative figures.

Cost in Euro/tonne of NOx Minimum MaximumHNO3 SCR (CRI) 420 450Burning plants/ waste incineration plants or gas turbines.SCR (CRI)

800 1500

LCI 800 MWth + SCR 1500 2500Refineries reducing their emissions to 200 mg/m3 (Frenchexamples)

1850 2350

SCR cement (Austrian evaluation) 966 1594Waste (1 French example/SCR) 9000Waste (Dutch reference) 3900 4400Glass SCR (from 2-1 to 0,5 g/m3) 1000 3000Glass SCR (from 1-0,7 to 0,5 g/m3) 3000 7000Flat glass (Euroglas example) SCR, gas combustion 650 1600Japanese refinery reducing its emissions to 65 mg/m3 3800 5640SCR: Selective Catalytic ReductionHNO3: nitric acidLCI: Large Combustion Installation

7.3 Comparing Reduction Technique Costs-Cement Selling Price Ratios

The cement industry wishes to draw attention to the reduction technique costs pertonne of cement to cement selling price ratio, which indicates the strong sensitivity ofthis industry to reduction costs. The average selling price of the cement tonne in 2001was 86€.

Reduction technique costs:(source: Solnhofen + tests + NOXCONF 2001)

1,9 to 3,6€/t cement, SCR technique, (2200 €/t of avoided NOx),0,7 to 1,8€/t cement, SNCR technique, (480 to 820 €/t of avoided NOx),

It would be interesting to compare this sensitivity to that of other industrial sectorsconcerned.

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8. Conclusions

This NOx reduction techniques test program, set up and carried out by the Frenchcement industry following the impetus of both the Ecology and SustainableDevelopment Ministry and ADEME, provided an industrial feed-back on several of thetechniques presented in the cement industry’s BREF document. But it obviously can’t provide answers for all of the field questions that may occur at plant level.

The important efforts engaged by the various actors of the French cement industryhave nonetheless resulted in a few interesting leads.

Similarly to what may be observed in other industrial sectors, NOx emissions reductionactions must start with primary reduction measures, as they have a much lowereconomic impact on the plant (67 to 2825 €/t of avoided NOx and 0,01 to 0,28€/t clinker, during our tests). Emissions can thus be reduced, and peaks in particular limited. This smoothing over will make later implementation of secondarymeasures that much easier (lower reactive agent consumption, possible less stringentrequirements on the inherent performance of the secondary measure).

These primary measures have also shown a further reduction potential. But theireffects are not systematically cumulative and problems of both reproducibility and ofbreakdown in kiln operating conditions were noted. Still it is more than probable thatprimary measures wiIl enable the plants to respect the 800 mg/Nm3 limit in most cases.The French cement industry has noted that tests done during 2000 already have adefinite impact on the average results for the industry:in 1999 and in 2000, emission averages collected by ATILH were respectively743 and 738 mg/Nm3. In 2001 and 2002, because of the tests program extending toother plant sites, the industry average went down to respectively 666 mg/Nm3 and667 mg/Nm3. This perceptible evolution should be taken into account when settingnational emission thresholds. Aiming for an industry average below500 mg/Nm3 for 2005 seems quite feasible.

When further emissions reductions become necessary, to conform to national emissionthresholds of 2010 for instance and come closer to the BAT performances described inthe BREF document, SNCR is then the least economically punishing technique(478 to 820 €/t of avoided NOx and 0,71 to 0,846 €/t clinker) for most ordinary production capacities. Progress could be made on the dominating cost of the reactiveagent by recycling ammonia water from the photographic industry for instance.Emission reduction of 40 to 70% were repeatedly observed during these tests, withhigh initial NOx values.

Performance levels are closely linked to installation lay-out and to a carefulimplementation of the SNCR technique.

SCR technique shows higher performance levels in other industries.But the cost of its implementation (2200 €/t of avoided NOx and 3,60 €/t clinker, estimates for the « low dust » technique) undeniably slows down its dissemination.There are currently no project within the cement industry to set up full scale tests forthis technique.

5 except Grave de Peille (test 7) with payback period of 5 years : 583 €/t NOx, and Val d'Azergues (test 8) where costs calculations were not validated by ADEME : 418€/t NOx6 except Cruas (test 13) with too small a capacity to be taken into overall account

- 15 -

An full-scale test of the "high dust" technique is currently under way at Solnhofen inGermany: it is early days yet to be able to judge its performances (2100 €/t of avoided NOx and 1,93€/t clinker) in view of the technical and economical elements provided.

For SO2 emissions reduction, presented here only through a single test operation,actions on both combustion process and absorbent injection seem to lead to a definiteemission reduction potential, even though results were relatively uneven.

- 16 -

Appendix 1

EVOLUTION OF NOX EMISSIONS REGULATION.

Nitrogen oxides (NO et NO2) are the object of particular attention from various publicauthorities at different levels.A the international level, what first comes to mind is the global perception of the issueas set in the Geneva Convention and in the NEC (National Emission Ceilings)Directive.Based on the modelisation of environmental impacts, of pollutant dispersion andtransportation and of treatment costs optimisation, these two parallel approaches haveresulted in setting global emission limits to the various countries working on thesubject.

France’s target emissions are as follows:Yearly NOx emissions (in Kt)

French 1999 emissions 1534Limit in 2010 (Göteborg Protocol) 860Limit in 2010 (NEC Directive) 810

Which means an overall industrial emission reduction of about 47 %.Emission reduction efforts will be distributed to each of the sources concerned.

This global approach at the European Union level has a technological complement inits IPPC (Integrated Pollution Prevention and Control) Directive.This directive stipulates that emission limit values for the facilities concerned (cementplants included) will be based on the performances of the Best Available Techniquesas of 1999 for new facilities and starting in 2007 for existing ones.Information exchanges were organised by the European Commission, to help memberstates implement this directive, and more precisely, help define the concept of BestAvailable Technique at an acceptable cost for the cement industry, in compliance witharticle 16.2 of the directive.The conclusions of these discussions were published in a document entitled BREF orBAT Reference Document, which should be referred to for all interpretations of theBest Available Technique (BAT) concept at an acceptable cost concerning cementindustry nitrogen oxides emissions reduction.

A short summary of these discussions can nonetheless be given here:

Emission levels for an operating Best Available Technique will have a daily averagebetween 200 and 500 mg/Nm3 at 10 % O2, dry gas, resulting from primary measure(flame temperature reduction, low-NOx burners,…), staged combustion or the SNCR technique, or any combination of these techniques.Members of the working group have nonetheless posited that a range at500-800 mg/Nm3 at 10 % O2, dry gas, would be more acceptable. The cement industryargues that the 200 mg/Nm3 value comes from the cement plant in Slite (Sweden), andshould be considered as a very particular case and not applied generally.

- 17 -

Other members who hold selective catalytic reduction (SCR) to be a BAT with theassociated emission level of 100-200 mg NOx/m3 (expressed as NO2 equivalents) havealso contested the daily average BAT in the 200-500 mg/Nm3 range. This last positionis based on feasibility studies, pilot tests and the fact that there are currently at leastthree suppliers in Europe proposing full-scale SCR units for the cement industry withperformance levels said to be at 100-200 mg/m3.But the commissioning of the first full-scale SCR unit in the cement sector was notplanned until the end of 1999 and in fact occurred much later.#This definition of BAT is completed by the following comments:- adaptability of individual facilities in respecting emission values in very site-specific:

it seems rather improbable to count on having every kiln reach these levels on agiven date.

- setting up a SNCR unit requires an adequate range of temperature being available.the correct temperature range is easily had on preheater kilns, onpreheater/precalciners kilns and probably on some Lepol kilns. There are currentlyno full-scale SNCR unit operating on a Lepol kiln, but tests made on pilot plantsgave promising results. It could turn out to be very difficult though, maybe evenimpossible, to obtain the necessary temperature and residence time in long wet/dryprocess kilns.

- there is a notable lack of SNCR experience in high reduction applications, and thus,an uncertainty concerning supplementary ammonia emissions that could comefrom the high injection rate of ammonia water. Ammonia slips could result in visibleand sustained sulphate dust and ammonia chloride emissions, and unusedammonia could also prevent recycling dust in the cement.

Lastly, the European Union set up limit emission values for the main pollutants in aclassic sector-specific approach to waste elimination activities.Thus, ministerial decree of 20 September 2002 transposing European directive of4 December 2000 pertaining to incineration and co-incineration facilities for hazardouswaste has set, for those cement plants where it is applicable, a limit value of 800mg/Nm3 for existing cement plants, and one of 500 mg/Nm3 for those new plantswhose main activity has been authorised after official publication of the decree.

Emission values for wet-process kilns, or those burning waste below 3 t/h can go as faras 1200 mg/Nm3 until 1st January 2008.Those few kilns who do not use waste remain regulated by the Decree of 3 May 1993,published in the Journal Officiel of 15 June 1993.Its main provisions concerning NOx are as follows:

Kiln type Limit Emission Value inmg/Nm3, dry gas

Dry process kilns with exhaust gas heat recovery for raw mealdrying

1200

Semi-dry or semi-wet process kilns 1500Wet and dry process kilns without exhaust gas heat recovery 1800They will be applicable to existing cement plants as of 15 June 1998, but areimmediately applicable to new plants.

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ADEME Convention n° 99-74-089 Summary Sheet: Project n° 1

Company: CIMENTS CALCIAPlant site: Gargenville (78)

NOx Emissions ReductionTest and Evaluation of Flue Gas Recirculation

1. Objectives

NOx emissions reduction in kiln from 1 000 to 800 mg/Nm3 at 10 % O2 ,dry gas, byrecirculating oxygen-poor flue gas (8,5 %) over the main kiln burner

NOx emissions reduction to less than 700 mg/Nm3 if coupling with water injectionsin the burner succeeds.

2. Plant and New Process Characteristics

Dry process kiln with HUMBOLDT 4-stage preheater and a production of 1 340 t/d,GRECO low NOx multiple-circulation burner, 4,7 % primary air + 1,8 % conveying air,Fuels: pet coke, animal fat, edible oils,Exhaust gas by-pass installation on heat exchanger and stack outputs, recirculation

to burner through dedusting cyclone, air-air exchanger, a Roots blower, cold air andflow control flaps, regulation and automation.

3. Results

Best absolute result: 884 mg/Nm3 by recirculation through axial air with waterinjection, that is 12 % reduction, with reduction from 13 to 19 % for other periods inaxial air,

14 % and 32 % reduction by radial air recirculation, with water injection, 24 % reduction by recirculation through the three air types with fresh air input and

without water injection,The last tests do not confirm the first results.

4. Conclusions

Objectives not met but promising results as reduced rates are important,Tests were disturbed by kiln operating problems, mostly because of blocked

vertical flues with no relation to the tests,Tests were realised under almost complete recirculation and without water injection

so as to measure process limitations and monitor the results over a long period,Costs were calculated after these rather unusual tests and as such, were based on

hypotheses not necessarily reproducible on a long term basis,Cost per reduced NOx tonne: 282€/t,Cost per manufactured clinker tonne: 0,17€/t clinker

- 19 -


Company: VICATPlant site: GRAVE de PEILLE (06)

Low-NOx Burner

1. Objectives

The initial objective of the test was to assess actual reduction gains after setting up a« Low NOx» burner and to check on the conformity to the suppliers’ claims.

This was a very complex subject, given the heterogeneity of raw materials in use andthe multitude of fuels burned on the plant site.But when setting up the initial program, it had nonetheless seemed interesting to try toassess the nitrogen oxide emissions reduction potential of the latest « Low-NOx »burner, set up on a kiln in replacement of an older burner, to test the effect of variouscontrol adjustments and, if relevant, to draw some useful rules and conclusions forfuture implementations.

2. Results

Suppliers FLS and Pillard refuse to guarantee NOx reduction gains with « Low-NOx »burners.

They claim that various other parameters such as fuel types, meal burnability, kilnoperating mode, also play an important role.

3. Conclusions

In view of the suppliers’ lack of confidence, the very high costs and the very important changes that would be wrought on the firing hood, Vicat decided to postpone theinvestment, which did not seem to be the best technique for reducing NOx emissions atthe Peille plant site.

Other techniques give significant results.

Potentially, a Low-NOx burner –setting up and auxiliary equipment included –wouldcost 450 k€, or 0,07€/t clinker.

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Company: HOLCIMPlant site: Altkirch (68)–Dry process kiln with 4-stage cyclone preheater

Evaluating Expert System Impact on NOx Emissions(with control variables not adjusted to NOx minimisation)

1. Test Programme

- Alternate continuous 7-days periods in conditions as identical as possible: LinkmanON ; Linkman OFF,

- Fuels,Kiln burner: 90% (pet coke, waste oils, solvents, treated sawdust)Precalcination: 10 % (tires, ground plastics),

- From 10/09/2001 to 27/11/2001, 11 weeks in total,

2. Results

Stacks EmissionsLinkman NOx CO SO2 O2 H2O CO2 Flow rate T

mg/Nm3 1O % O2 % % % Nm3/h °CON 523 1032 4,0 8,6 19,3 13,8 109.600 131OFF 538 818 3,0 8,8 19,1 13,5 111.700 133

Classdistributionofhalf-hourNOxemissionaverages

forkilnoperatingperiodswithandwithoutexpert system(valuesgiveninmg/Nm3,10%O2,drygas)

1% 1%3%

6%

12%

16%18%

16%

9%

5%6% 5%

1%0% 0%0% 0%

1%3%

7%

12%

16%

19% 19%

13%

6%

3%1% 1% 0%

0%2%4%6%

8%10%12%14%16%18%20%

25 75 125 175 225 275 325 375 425 475 525 575 625 675 725 775 825 875 925 975

LinkmanOFF

LinkmanON

LINKMANON

nbr. values=1198AVERAGE=523min. value=164max. value=926Std.deviation=105

LINKMANOFF

nbr. values=808AVERAGE=538min. value=225max. value=915Std.deviation=126

3. Conclusions

- alternate Linkman ON/OFF7 campaigns showed similar NOx emission levels,- yet histograms show a reduction of NOx emissions in the higher values, over 700 mg/Nm3,- in our opinion, the fact that the expert system has been in use for quite some timehere has lead to an harmonisation of the kiln staff’s operating procedures, which has in turn influenced the results, when compared to usual assessments.

7 ) The facility already had an expert system, which would today require an investment of about 210 k€. The ABB company which supplies the expert system does not have a specific module for NOx reduction

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ADEME Convention n°99-74-179 Summary Sheet: Project n° 4

Company: IRMA

Selective Catalytic Reduction of Nitrogen Oxides

1. Objectives

Run laboratory-scale tests of selective catalytic reduction of nitrogen oxides usingammonia on gaseous compound with a composition close to that of cement planteffluents, but without the dust.

2. Programme

Testing catalysts based on zeolithes exchanged by various cations:- Pentasil zeolithe copper 2,3 %, ammonium form, 127 g/l of active matter,- Pentasil zeolithe copper 2,3 %, platinum 0,2%, 161 g/l of active matter,- Pentasil zeolithe Si/Al: 13,5, iron: 2,5 %, ammonium form, 200 g/l of active matter,- Pentasil zeolithe Fe: 3,2 %, 134 g/l of active matter,- Pentasil zeolithe Si/Al: 13,5, platinum: 0,54 %, sodic form, 117 g/l of active matter,- commercial catalyst of the V2O5-TiO2 type

3. Results

Copper and iron Pentasils have rather similar behaviour. Both catalysts are stable at300°C and deactivation below this temperature (275°C) is quite clear: NOxtransformation rate drops quickly due to ammonium sulphate formation that clogsporosity and restrains access to active sites.

Adding platinum to copper Pentasil seems interesting, as it lowers reactiontemperatures. There were 85 % of NOx conversion at 300°C during 70 h, but with aNH3/NO ratio of 1,3. There is slightly more N2O, which seems unavoidable in thepresence of platinum. A platinum zeolithe with a NO2-rich compound can manage toeschew N2O, but deactivation, though real enough, is rather slow. This catalyst wouldgive interesting resuslt in cycle runs of a day or two, with two catalyst beds and and aperiodic regeneration.

4. Conclusion

Selective catalytic reduction tests give acceptable results at temperatures over 300°C,without dust. But gases at these temperatures in the cement manufacturing processare loaded with dust (around 10-100 g/Nm3), being upstream of dedusting. Dedustedgases are at lower temperatures which won’t allow catalytic reaction.Investments for an SCR unit with dedusted gas reheating is estimated at 8,2 M€ for a 3600 t/d kiln. Operating costs would be 3,6€/t clinker, and 2200 € per tonne of avoided NOx, with an increase in exhaust gas volume of 15 %. In other industrial sectors, NOxreduction rates can reach 80-90 % with favourable temperature and dust loadingconditions.The Solnhofen plant site in Germany has done full-scale tests, which results arepresented in sheet 4bis.

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Solnhofen Project Summary Sheet: 4 bis

Company: Solnhofer Portland-Zementwerke A.G.Plant site: Solnhofen (Germany)

Selective Catalytic Reduction of Nitrogen Oxides on an Industrial Scale(information provided by the cement industry)

1. Objectives

Reduction of NOx emissions to less than 800 mg/Nm3 at 10 % O2, dry gas, by running dustloaded hot gases through a selective catalytic reduction system.


Dry process, preheater kiln with production capacity of 1500 t/dThe SCR system is set-up at the preheater lower end, connected to its output duct withpossible by-pass. Exhaust gas flow through the catalysts from top-down under normal operatingconditions and bottom-up 20 % of the time, to improve catalyst grate dust cleaning. Pressionloss of the installation is of 5 to 9 mb. Catalyst lifetime expectation is 3 years.Ammonia injection for SCR is done at preheater output end,NOx emissions reduction tests with SNCR were also done at this plant site with a

stoichiometry of 1,8.

3. Results

The NOx selective catalytic reduction system has now been working without major problemsfor 9 000 hours. NOx emissions were reduced from 1200 to 800 mg/Nm3 with0,6 stoichiometry at a temperature of 300°C.

According to the supplier, SCR technology could reduce emissions from other pollutants, butthis has not been verified.

To this day, no record of unusual equipment wear.

4. Conclusions

Information given during the 1st October 02 tour of Solnhofen was provided by the SCRsystem supplier (LURGI). As such, it is theoretical and does not necessarily pan out withelements previously given out by the cement plant, for reasons both of confidentiality and oflack of previous industrial application characterization. This somewhat strains the credibility ofthe information given to the visiting delegation.

The system seems to be operating satisfactorily.The plant operator thinks that an SNCR system is enough, and that the main interest of SCR

is to avoid ammonia (NH3) stack emissions.Capital investments in Solnhofen were of 3,5 M€. Capital investments are estimated at 2,5 M€

for a 1500 t clinker/day kiln, to which general set-up operations and necessary preheateradaptations must be added.

This technique seems to work, but we have seen that primary measures in France decreasedemissions from 1200 to 800 mg/Nm3. The motive put forward for choosing SCR seems difficultto believe: no NH3 stack emissions and foreseeable savings if NOx rates can be reduced.

The VDZ (Verein Deutscher Zementwerke e.V.) has been following this test, and though nocertified operational summary has been done up to now, records that the technique seems towork.

Operating costs are 0,75€/t clinker for a reduction of 400 mg/Nm3

Maintenance costs are mostly catalysts replacement costs: 7 500 to 15 000 €/m3, whichmeans an added 0,5 to 1€/t clinker

Total costs hover from 1,93 to 2,43€/t clinker, or again 2100 to 2640 €/t of reduced NOx .

These elements still being theoretical today, the technological and economical context of SCRimplementation remains in need of further precision and validation.

- 23 -


Company: LAFARGE ALUMINATESPlant site: Le Teil

Setting up an Expert System for Reducing NOx Emissionson a Calcium Aluminate Cement Production Line

1. Objectives

A reduction of about 20% in the NOx stack emissions of the Le Teil plant productionline, using expert system LUCIE. More ambitious yet, reduce the exhaust gas NOxconcentration below the 800 mg/Nm3 threshold (with 10 % O2, dry gas), starting from aninitial concentration of 1207 mg/Nm3, as measured by the AIF (certified third-bodyagency) before expert system set-up.

2. Programme

1) Measure NOx emissions during five days before expert system installation2) Set up expert system3) Measure NOx emissions during five days after expert system installation4) Modify expert system targets5) Measure NOx emissions during five days after expert system modification.

We intended to add two more sensors on the process line:- an infra-red camera for the thermal characterization of the burning zone, which

idea was abandoned after an unhappy experience on our West Thurrock plantsite (too sensitive to dust emissions).

- a continuous NO analyser on the stack, also abandoned, because the NO kilnoutput analyser which had us worried at the beginning of the program finallyoperated quite normally.

3. Modifications Outside the Program

We changed the air gas cooler before the electrofilter to a combined air/water gascooler, which increased production at an identical flow rate.

4. Results of AIF measurements

Step 1) 878 mg/Nm3, at 13 % O2, dry gas, or 1207 mg/Nm3 at 10 % O2 dry gasStep 3) 893 mg/Nm3, at 9,8 % O2, dry gas, or 877 mg/Nm3, at 10 % O2 dry gasStep 5) June 02 measurements: 847 mg/Nm3 at 10 % O2, dry gas, (on one dayonly)NOx rate flow per tonne of manufactured clinker went from 2,22 kg/t to 1,79 kg/twith the expert system, then to a further 1,32 kg/t after optimisation.

5. Conclusions

NOx concentration was reduced by 30 % using the expert system, more than wasaimed for (20%), but couldn’t be reduced below 800mg/Nm3.Capital investment for expert system modification 60 k€.Costs per reduced tonne of NOx: 226€/t,Costs per tonne of manufactured clinker: 0,20€/t clinker.

- 24 -

Convention ADEME n° 99-74-181 Summary Sheet: Project n° 6

Company: CIMENTS CALCIAPlant site: Gargenville (78)

NOx Emissions ReductionTest and Evaluation of Water Injection with Additives

1. Objectives

Kiln NOx emissions reduction from 1000 to 800 mg/Nm3, at 10 % O2, dry gas, byinjecting pure water or water with added domestic fuel on the flame and in thesecondary air duct.


Dry process kiln with HUMBOLDT 4-stage preheater and a production of 1340 t/d,GRECO low NOx multiple-circulation burner, 4,7 % primary air + 1,8 % conveying air,Fuels: pet coke, animal fat, edible oils,Injection of 500 to 2000 l/h pure water, then with added domestic fuel, in the flame

centre with a injector rod using compressed air,Injection of pure water in kiln secondary air duct,NOx measured at the stack, controlled through water flow rate.

3. Results

Cutting-off of higher values through flame injection: average about 100 mg/Nm3

lower, and measurement standard-deviation decreased from 286 to 126 mg/Nm3,Best results: 947 mg/Nm3 with pure water, 930 mg/Nm3 with additives,Kiln operation breakdowns at the beginning of the tests, under control afterwards,Differences in water injection with and without additives not noticeable,No secondary air injection reduction observed, as tests were interrupted for the fluegas recirculation tests.

4. Conclusions

On a Low-NOx burner with low primary air rate, injecting water in the flame clips thehighest values but hasn’t any noticeable impact on the overall average,

Water injection implies smoother kiln operations, banning too abrupt actions on fuelflow rate,

Injection has no noticeable effect on kiln thermal rate and consumption.Capital investments: 10 000€Costs per reduced tonne of NOx: 184€/tCosts per tonne of manufactured clinker: 0,06€/t clinker

- 25 -


Company: VICATPlant site: Grave de Peille (06)

Injection of Water with Organic Additives

1. ObjectivesDefine optimal injection conditions of water with additives to obtain the highest possiblereduction of nitrogen oxide emissions.

2. ResultsReference data: the following conclusions concerning « standard » cycle runs withoutorganic water injections are based on the average quarter-hour readings and the dailyaverages (7400 values): up until the beginning of 2001, for reasons of greaterburnability, kiln operators maintained excess air in kiln feed end at 6%. NOx emissionrate expressed at 11% O2 had an average of 1150 mg/Nm3 with peaks at1400-1600 mg/Nm3 (on 246 daily averages). Since the beginning of 2001 efforts weremade to keep oxygen level at a maximum of 3 to 4%, which incidentally heightens therisk of CO formation. NOx emissions were reduced to 903 mg/Nm3 (on162 daily averages). Peaks were limited to 1200-1300 mg/Nm3. Since November 2001,an expert system has again reduced the average rate and cut out the peaks over 1100mg/Nm3. The tighter monitoring of oxygen level at kiln feed end is very probably behindthis.

The fuel type PITCH or PET COKE has had no noticeable influence on the emissionrate during the tests.

Water injection tests, with and without hydrocarbons were run several times during the500 h kiln operation, in several campaigns. Flow rates of 500 l/h of water + 200 l/h ofhydrocarbons were required before NOx decrease became noticeable, about 200 to300 mg/Nm3 less in the 900 mg/Nm3 zone. Water without hydrocarbons at identical flowrates has no impact.

3. Conclusions

On the whole, these tests turned out to be positive for the plant since emissions wentfrom 1200 to 850 mg/Nm3, gaining from this action combined with oxygen ratereduction at kiln feed end,

Capital investments for a continuous injection of water with hydrocarbons would beabout 116 000€, with payback in 5 years at 6%,

Operating costs (compressed air and pumps): 60 kWh at 0,04 € or 2,4 €/h (16 800€/year). Maintenance: 10 000 €/year,

Flame yield loss: 0,5 t/h evaporation = 9€/h (63000€/year),Total = 89 800€/year + (116 000 €/4,21) = 117353€/year,Costs per reduced tonne of NOx: 583€/t,Costs per tonne of manufactured clinker: 0,19€/t clinker,

- 26 -


Company: LAFARGE CIMENTSPlant site: Val d'Azergues (69)

Nitrogen Oxide Emissions Reduction.Test and Evaluation of Water Injection with Additives

The use of waste in cement plants for more than 10 years has showed a positiveinfluence of aqueous waste on nitrogen oxide emissions. This phenomenon is site-specific but in certain situations can reduce emission levels by almost 40 %.

1. ObjectivesThere are two key parameters to this NOx emission minimisation when using aqueouswaste: temperature, and the volatile contents of said waste.Several types of aqueous waste are tested, with various organic matter contents,injected at the main kiln burner, near the main kiln burner and at the Lepol kiln grateburner.Industrial runs without aqueous waste are also tested.

ADEME aimed to reduce NOx emissions below 800 mg/Nm3, at 10 % O2, dry gas.

2. TestsAqueous waste injection tests were done at the main kiln burner and at the Lepol kilngrate burner to determine their impact on NOx reduction. Several test configurationwere run:

– Variation of aqueous waste flow rate– Variation of aqueous waste organic matter contents– Variation of injection locations

3. ResultsAt grate burner: - 10 % NOx reduction by injection of G2000

- 10 % to 25 % NOx reduction by injection of G3000At kiln burner: - 25 % NOx reduction by injection of G2000

- optimisation of configuration by central injection

4. ConclusionsShort tests showed, for the G2000 burner flow rate of 20 l/t clinker:Positive

– 25 % NOx reduction (not found by certified third-body)– No impact on clinker quality

Negative– 3 to 7% less in clinker production– 35 th/t clinker increase in heat consumption– A less even process run

Costs, provided by Lafarge Ciments- Capital investments: 600 000€ (aqueous waste acceptance, storage and injection)- Costs per reduced tonne of NOx: 418€/t- Costs per tonne of manufactured clinker: 0,23€/t clinker

In Lafarge’s costs calculation of NOx technique, product tax, investment payback and installation maintenance were held to compensate one another. Water evaporation and production loss of72400€/year were taken into account as well as clinker production of 315000 t/year and NOx reduction of173 t/year. Several of these hypotheses, however, could not be verified very precisely.

- 27 -

Convention ADEME n° 99-74-184 Summary Sheet: Project n° 9

Company: LAFARGE CIMENTSPlant site: Port-la-Nouvelle (11)

NOx Emissions Reduction by Staged Combustion

The Port-la-Nouvelle plant was modernised in 1998, with, among other majorinnovations in the kiln line, the setting up of a CLE Technip precalciner operating on thestaged combustion principle (MINOX process). According to Lafarge Ciments, Port-la-Nouvelle’s MINOX was designed to operate with 100 % sulfurated pet coke.

1. Objectives

- Define possible technical hitches in implementing the MINOX process,- Validate process performances- Asses its economic impact,- Reduce NOx emissions below 500 mg/Nm3 (at 10 % O2)- Maintain CO emissions and combustion residues at their present levels,- Keep the kiln line running smoothly.

2. Tests

Three sets of test were necessary before reaching a quasi industrial operating levelduring a week. It was impossible to produce clinker in satisfactory operating conditionsduring the first sets: reducing conditions set off very high SO2 volatilisation which inturn rapidly clogged the kiln end. The system’s aeraulics were also very difficult to manage.

Important modifications to the installation had to be made to improve its operations:adding a burner to the precalciner, modifying the tertiary air dampers, improving feedline inlet…

Furthermore, during the last tests set, there occurred a period where the raw mealburned very easily and COMBSU (waste fuel) was injected at the burner. Kilnemissions were thus quite lower during all this period.

3. Conclusions

Positive:- decrease of stacks NOx down to 800mg/Nm3, at times, (impact of the

precalciner burner),- positive impact of waste fuels,- positive impact of the new precalciner burner.

Negative:- process difficulties (ring formation, concretion),- up to 10 % loss in production- according to Lafarge Ciments, operating the MINOX with the contractual fuel

did not lead to the expected performances.

Set-up costs of MINOX process: from 1 to 1,5 M€, in the case where the plant already has a precalciner,

Costs per reduced tonne of NOx: non viability of reduction technique at industriallevel of operation,

Costs per tonne of manufactured clinker: 0,28€ /t clinker,

- 28 -


Company: LAFARGE CIMENTSPlant site: Saint-Pierre-la-Cour (53)

SNCR on Dry Process Kiln with Precalciner

The Saint-Pierre-La-Cour plant of Lafarge Ciments agreed to test SNCR NOx reductionand reduce NOx emissions below 500 mg/Nm3, at 10 % O2, dry gas.

1. Objectives1. Define possible technical hitches2. Validate process performances3. Asses its economic impact4. Reduce NOx emissions below 500 mg/Nm3 at 10 % O2.

without deteriorating equipment operationswithout increasing, and if possible, on the contrary, decreasing other

emissions (residual NH3,…)

2 . TestsAn alkali solution (25% NH3) was injected on both gas flows, that in the preheater kilnburner and that in the precalciner burner, to determine their respective reaction rates. DSeveral test configuration were run:

Variation of ammonia flow rate with a NH3/NO molar ratio of 0 to 3Optimisation in injector site distribution on the equipmentVariation of injector type

With a NH3/NO molar ratio of 1, NOx reduction were of: 80 % on the preheater kiln line, for downstream combustion NOx 70 % on the precalciner line, for upstream combustion NOx

These results are in conformity with those found in professional literature. These testslead to finding the optimal configuration for a 15-days continuous run, as defined inproject specifications.

3. ConclusionsPositive: NOx reduction from 1200 to 500 mg/Nm3, no particular smell to recycleddust. Measurements at the stacks done by monitoring body have shown emissionlevels as low as 430 mg/Nm3,Negative: 2 % loss in production, calculated energy consumption increase of 1 %,combustion deterioration (more concretions),Capital investment: 1 130 000€Costs per reduced tonne of NOx: 478€/tCosts per tonne of manufactured clinker: 0,71€/t clinkerComments:

- Electrofilters: a slight increase in dust emission as the tests ran on.- NH3 increase during tests, to maximum 10mg/Nm3 what about slips in the long-term ?

- 29 -


Company: HOLCIMPlant site: Héming (57)–Semi-dry process with LEPOL grate kiln (1200 t/d)

Test and Evaluation of Urea SNCR on a Semi-dry Process Kiln

1. Test Programme

SNCR performance was judged on:1. The NOx reduction rate (APAVE measurements),2. The incidence on other emissions (NH3, CO, N2O, SO2, COV) (APAVE

measurements),3. The presence of smells in emissions or recycled dust (IAP International Sentic),Limited in time, these tests did not allow assessing the impact on:1. Additional concretion formation and possible clinker production loss,2. Health and safety (working in the filters, in particular),3. Additional maintenance costs due to corrosion,

2. Calendar

Objectives Period lengthPreliminary test Show feasibility 1 dayOptimisation tests Optimisation of

injection parameters4 days(3 to 6h injection per day)

Long-term tests urea SNCR evaluation 2 campaigns of 4x24 continuoushours

3. Results and conclusionsAqueous urea solutions SNCR can be applied to a LEPOL kiln. Performances displayedin long-term tests are:

NH2/NO2 NOx reduced rate Urea costs 1 Total costs payback included 2

kg/t clinker €/ t clinker €/ t clinker €/ t reduced NOx

1 37 % 3,6 0,43 0,60 675

1,5 43 % 5,4 0,65 0,84 8201 0,12€/ kg urea2 capital investments of 510.000€ (10 year payback period, at 6 %)

N2O, CO, SO2: undetectable impacts of SNCR on those emissions.

NH3: slip < 10 mg/Nm3 at 10 % O2, dry gas, with a stoichiometry of 1, up to 13 mg/Nm3

at 10 % O2, dry gas, with a stoichiometry of 1,5.

Smells: a slight smell is detected in kiln dust due to amine residue fixation. Aftermixing the dust with cement, the olfactory impact seems minor.

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Company: HOLCIMPlant site: Lumbres (62)–wet process kiln

Test and Evaluation of Urea SNCR on a Wet Process Kiln

1. Tests programme

The programme laid out in the convention was only partially realised as technicalproblems occurred which could not be solved within time frame of ATILH / ADEMEconvention

Partial programme :

Setting up an experimental injection line on a rotary kiln:1. Set up 2 lines, one for air, the other for the water + urea mix,2. Feed the 2 sets of 3 injectors in mid-kiln (1050°C and 1100°C),3. Look for solutions to improve technique reliability.Short term SNCR tests

2. Calendar

Objectives Period lengthPreliminary Test Show feasibility 1 dayExperimental line Development and realisationOptimisation tests Optimisation of injection

parameters4 days(3 to 6h injection per day)

Improvements Repair and modify injection circuitsto make them more reliablePurchase injection gantry andNH3 Canal

Circuit testing Arrive at permanent air and waterinjections

6 months

Urea injection SNCR test with sole injector stilloperational

19 tests in 13 days

3. Results

Results of these short term tests show a NOx reduction potential from 20 to 70 %, withammonia slip problems whatever the reduction rate. These results were obtainedwithout optimising the injection circuit (use of 5 injectors on the 6 available with astoichiometric molar ratio of 1,5) and need confirmation.

Nozzle orientation can probably also play a major role in technique performance and inNH3 slip control, which latter could turn out to be problematical if unchecked.

4. Conclusion

Failure of continuous urea injection: for technical reasons, mainly, thermal resistanceof kiln linings, injector build-ups, vibration resistance of double rotary connections andthermal stress of conveying pipes alongside the kiln.

A complementary programme exceeding convention time limit is currently under way.

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ADEME Convention n°99-74-188 Summary Sheet: Project n° 13

Company: CIMENTS CALCIAPlant site: Cruas (07)

NOx Emissions ReductionTest and Evaluation of SNCR on White Cement Production Unit.

1. Objectives

NOx emissions reduction of kiln below 500 mg/Nm3, at 10 % O2, dry gas, withoutdeterioration of facility operations. Short-term ammonia injection test, then long-termurea injection test.


2 stage dry process kiln with 570 t/d capacity and clinker cooling system by waterimmersion,

450°C primary air mono-circuit burner,Fuels: pet coke and high viscosity fuels,Urea solution at 43,5% or ammonia solution at 20,5% injected in the vertical

heating duct through 2 or 4 injectors with air and water compression, Injection rate: 50 to 200 l/h urea, 73 to 219 l/h ammonia,Exhaust gas analysis through continuous MIR 9000 system (O2, NOx) and FTIR

Gazmet analyser (NH3, N2O, NO, NO2),NOx emission control by reactive agent rate flow .

3. Results

NOx reduction to 800 mg/Nm3 with 150 l/h urea, residual ammonia emission of 75mg/Nm3,

Reduction to 500 mg/Nm3 with 200 l/h urea, residual emission at 170 mg/Nm3,Similar results with ammonia: slightly less efficient NO reduction, and higher

residual emissions of ammonia, but lower N2O et NO2 emissions,Tendency concretion formation in vertical heating duct,Kiln draft breakdown and exhaust gas cooling with water sprays leads to a slightly

lower kiln flow rate.

4. Conclusions

Reduction objectives reached using 150 à 200 l/h urea, but high residual emissionsof ammonia, probably due to the small dimensions of unit which meant too short aresidence time (200 ms)

Optimisation of injection conditions could not reduce residual emissions.Capital investment: 600 000€Costs per reduced tonne of NOx: 622€/tCosts per tonne of manufactured clinker: 1,76€/t clinker

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Company: CIMENTS CALCIAPlant site: Beffes (18)

Emission Reduction of Sulphur OxidesTest and Evaluation of Raw Meal, Lime and Carbonate Injections

1. Objectives

SO2 emission reduction of at least 50 %, that is below 400 mg/Nm3, at 10 % O2, drygas, through raw meal, lime and sodium bicarbonate injections.


semi-dry process LEPOL kiln with precalcination and a capacity of 1750 t/d,fuels: pet coke, meat and bone meal, treated sawdust,injection equipment: 150 m3 silo with filter, extraction sieve, weighing hopper, Roots

blower and rotary valves, pipes, and a reactive agent flow rate adjustable from 100 to1000 kg/h

injection locations: recirculation duct, decarbonation chamber, grate outlet duct.

3. Results

SO2 residual emission:

321 mg/Nm3 that is–52 % with 480 kg/h raw meal in recirculation duct,686 mg/Nm3 that is–27 % with 200 kg/h lime in recirculation duct,325 mg/Nm3 that is–49 % with 200 kg/h sodium bicarbonate in recirculation duct,794 mg/Nm3 that is–31 % with 200 kg/h lime at grate outlet,No reduction through raw meal or lime injection at precalciner levelResults are better with low CO content in exhaust gas.

4. Conclusions

Significant reductions with injection in recirculation duct, but initial objectives are metonly under favourable conditions when CO contents in exhaust gas are low,

Results not easily reproducible and not necessarily in proportion to injected reactiveagent flow rate,

Best results are with sodium bicarbonate but we note an increase of alcali contents inthe clinker, detrimental to cement quality in general, and to Beffes cements inparticular, as their alcali contents is already high.

Tests to be continued, working on the combustion first, to reduce exhaust gas COcontents, and thus SO2.

Capital investment: 214 500€Costs per reduced tonne of SO2: 943€/t with lime, 146€/t with raw mealCosts per tonne of manufactured clinker: 0,55€/t clinker with lime,

0,12€/t clinker with raw meal

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Company: VICATPlant site: Grave de Peille (06)

Expert System

1. ObjectivesDevelopment of a set of control variables complementary to existing expert systemrules that will minimise NOx emissions while maintaining a high combustion.

2. First results with expert system operating without specific variablesA significant improvement in NOx emissions is noted, through the disappearance ofpeaks/peaks over 900 mg/Nm3, which already represents a gain of about a hundredmg/Nm3. From 2000 to 2001, simply lowering the oxygen from 6 to 4% at kiln feed endreduced NOx emission around 200 mg/Nm3.

3. Results with expert system operating with specific variables

Specific NOx variables resulted in a sustainable 2 % oxygen rate, which is lower thanwhat an operator can manage to obtain permanently on this kiln. This leads to a100 mg/Nm3 gain. Other factors also apply, such as meal burnability as characterisedby its chemical composition and fineness as well as by the regularity of its composition,which can lead to a 200 to 300 mg/Nm3 gain.

4. Conclusions- 1200 mg/Nm3 initially

- 1100 mg/Nm3 when following feed end oxygen rate at 4 %.- 950 mg/Nm3 with classic expert system- 800 mg/Nm3 with specific variables

Costs- Capital investment for expert NOx system module: 59 000 €,- No day-to-day expenses,- Expected reduction: 120 t NOx per year,- Costs per avoided tonne of NOx: 67€/t NOx,- Costs per tonne of manufactured clinker: 0,01€/t clinker

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NOx at 11%O2 (without water injection) Jan to Nov 2001

2001 average: 903 mg/Nm3 (162 daily averages)2000 average: 1150 mg/Nm3 (246 daily averages)

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837 mg/Nm3 average in nov 2001 with expert system

with expert system

guide nox anglais - ademe

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