Performance of PAHs emission from bituminous coal combustion

155Yan et al. /J Zhejiang Univ SCI 2004 5(12): 1554-1564Journal of Zhejiang University SCIENCEISSN1009-3095IZUPerformance of pahs emission from bituminous coal combustionYan Jian-hua(严建华), YOU Xiao-fang(尤孝方, LI Xiao-dong(李晓东),NI Ming- Jlang(倪明江), YIN Xue-feng(尹雪峰, ceN Ke-fa(岑可法)(National Key Lab of MOE Clean Energy and Environmental Engineering, Zhejiang University, Hangzhou 310027, China)TE-mail:yanjh@cmeezju.edu.cnReceived Sept 4, 2003; revision accepted May 26, 2004Abstract: Carcinogenic and mutagenic polycyclic aromatic hydrocarbons(PAHs) generated in coal combustion havecaused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plusBenzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. Theffects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigatedTwo additives(copper and cupric oxide) were added when the coal was burned. The results indicated that significantquantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and thattemperature is an important causative factor of PAHs formation. PAHS concentrations decrease with the increase of chlorinecontent in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PaHs formation(especially themulti-ring PAHs) during coal combustionKey words: Polycyclic aromatic hydrocarbons(PAHs), Organic pollutants, Bituminous coal, Combustiondoi:10.1631/jzus.2004.1554Document code: ACLC number: X511INTRODUCTIONgeneration, road transportation, and incinerationare the major PAHs emission sources. Some PahsPolycyclic aromatic hydrocarbons (PAHs) indicators of different processes have been identi-have caused great environmental health concern fied. Chrysene and benzo(k)fluoranthene are indi-because of their carcinogenic and mutagenic char- cators of coal combustion, and pyrene andacteristics, although the amounts of the organic fluoranthene are associated with incineration ThePAHs pollutants emitted into the environment are most toxic PAHs, benzo(a)pyrene(BaP), emittedlower than those of the inorganic pollutants suchfrom boilers accounts for 51. 6% of the total baPSO2, NOx, and CO. PAHs may be formed during emissions in the world (Sai, 1995)nefficient combustion of fossil fuels(petroleumCoal is mainly composed of a wide variety ofcoal and so on), wood, paper, and tobacco that organic structures such as aromatic clusters, alicontain carbon and hydrogen, or produced during phatic bridges and rings, side chains, and oxygenpyrolytic process. Usually, anthropogenic and in- functional groups(Solomon et al., 1988).Upondustrial processes such as home heating, power heating, coal structures undergo major physical andchemical changes and release volatile organiProject supported by the National Natural Science Foundationcompounds. CO and Cha are also produced becauseof China(Nos. N59836210, N1986259878047), and the National of the rupture of the function groups in coalBasic Reaearch Program (973)of China(No. G1999022211)Weaker bonds中国煤化工 ings breakCNMHGYan et al. /J Zhejiang Univ SC/ 2004 5(12): 1554-1564up first, then the aromatic structures, resulting in from 900oC to 1000C. Another study showedmore aromatic hydrocarbons produced in the increase of P AHs yields resulted from the pyrolysisproductsof a coal with increasing temperature at about 600PAHs formation during coal combustion C(Ledesma et al, 2000)process may occur through complex pathwaysThe external influences of combustion tem-There are two important factors influencing PAHs perature, excess air, and coal rank on PAHs emisemission in coal combustion:(1)the unburned sion from fluidized bed combustion had beenc ganic materials because of the poor combustion studied(Mastral et al., 1998a;1998b; 1999; 2000onditions(Mastral et al., 1998a; 2000), and(2)the2000: Liu et al. 2001: Yan etinitial stage of pyrolysis process in the combustion al. 1996resultssuggestedthat pahs(Astral et al., 1998b). PAHs emission from energy emission increased first and then decreased withgeneration has been reviewed, including emission increasing temperature. When the residence timesources,sampling, extraction and measurement increased, the total PAHs emission decreased(Liutechniques, and the influences of the fuel and et al., 2001). There is a specific PAHs emissioncombustor type (automobile engines, domestic trend that follows the combustion temperaturecombustors, industrial stokers and fluidized bed PAHs in the gas phase are higher than those in thecombustors)on PAHs emission. Pyrolysis and py- solid phase. The higher the percentage of excess air,rosynthesis are the two main PAHs formation the lower the total PAHs emitted. Lower percentagemechanisms(Mastral and Callen, 2000; Ni et al., of excess air could favor the deposition of PAHs on2003)the more stable particulate matters, while the higherAlthough the influence of coal structure on percentage of excess air could favor the shift ofPAHs emissions from coal combustion is not well PAHs to the gas phase. There will be a sluggingunderstood, the other factors that influence PAHs regime at higher flows causing PAHs yields toemissions had been studied (Liu et al, 2001; Li et increase(Mastral et al., 1998a; 1999)al, 2003). The influences of chlorine and sulfurThe effects of adding desulfurizcontents in coal on PAHs emission had also been coal combustion on pahs emission had beenexamined. They included the different influences of studied experimentally(liu et al. 2001: Astral etorganic chlorine and inorganic chlorine on the dis- aL, 2001a). Their results showed that more PAHstribution of PAHs in the gas phase and solid phase tended to concentrate on the solid phase whenemission (liu et al, 2001)limestone was added to the reactorTotal PAHs emission depends mainly on theMetal additives have little influence on lowpyrolitic process and to a lesser degree on the molecular weight compound(C1-C4)formationcombustion efficiency. A study conducted by Us With decreasing flame temperature, iron(Fe)isEPA (Miller, 1994) suggested that the efficient released as a metal in gas phase, and manganesecombustion conditions in the pulverized coal-fired (Mn) is released as an oxide. They form active sitesboilers had very little potential for PAH emissions. on particle surfaces and can catalyze PAHs and sootDifferent types of free radicals, aromatic and alkyl formation with the reaction of acetylene(Feitelbergstructures undergo association through cyclization, et aL., 1993 ). The presence of chloride has distinc-can lead to PAHS formation. Once the coal com- tive influence on organic compound formationbustion efficiency is optimized, the pyrosynthetic Under oxygen deficient condition, the addition of aprocess has very important influence on PAHs metal chloride can promote thermal decompositionformation. The effect of temperature on PAHs of PE and form PAHs with the participation ofproduced from the pyrolysis of a bituminous coal in benzene(Wey et al., 2000)a drop-tube reactor had been studied Wornat et alBased on the above analysis, to gain under-1987). Their results showed that PAHs products standing of P AHs formation from coal combustiondecreased as the pyrolysis temperature increased process, PAHs中国煤化工1 ous coalsCNMHG1556Yan et al. /J Zhejiang Univ SC/ 2004 5(12): 1554-1564were analyzed and PAHs distribution from coal methane/n-hexane (V/: 2/1 15 ml in 3 times ),combustion was determined. Furthermore, the in- anhydrous alcohol (10 ml) and chloroform(10 ml)fluences of chlorine and heavy metal on PAHs were used to elute different organic compoundsformation were studied. The results are reported in with increasing polarity of the compounds as alithis paper.phatic hydrocarbons, aromatic hydrocarbons, andpolar compounds. The solvent of the eluted liquidwas vaporized at 40C and the residue was kept in aEXPERIMENTS AND PROCEDUREvacuum oven for 30 minutes at a pressure of5.33x10* Pa, then stored in desiccator for 30 minAnalysis of PAHs content in raw coalsutes before the mass was weighed. The conditionsFive Chinese bituminous coals were analyzed for analyzing the extracts of these five coals using aor PAHs content. Proximate and ultimate analyses gas chromatograph coupled with a mass specof the five coals are listed in table 1trometer(GC/MS) are listed in table 2Coal(5.0000 g)was mixed with quartz sandextracted for 18 hours in a Soxhlet apparatus with Experimental proceduredichloromethsolvent, The solution was thenAll combustion experiments were carried outconcentrated to 2-3 ml in a rotary vapor. N-hein a laboratory-scale tubular furnace shown in Fig. 1was used to deposit pitch matter, silica gel and The furnace temperature was regulated to the sealuminum oxide were filled in a chromatograph point(+20C)by the electric heating equipmentcolumn N-hexane(20 ml in 4 times ), dichloroEach time 0.5000 gram of coal(80-400 mesh)Table 1 Analysis of bituminous coalCoalProximate analysisUltimate analysis (%Ma(0%o)And(%)Va(%)FCad(%o)Onetad (MJ/kg) Cad Had Ond Nad SadDatong4.666.5954.8227.503.4710.150.84Zaozhuang1.8418.1029.43Yanzhou1.8219.6930.46480263454.069.001.270.700.792.7019.0857.429.1466644.440.891.383.16Datun2.218.2422.4837.07186746.943.237960.940.48Table 2 GC-Ms analytical condition for aliphatic hydrocarbons, aromatic hydrocarbons, and polar compoundsCompoundAliphatic hydrocarbonsAromatic hydrPolar compoundsColumnDB-5,30m×0.25mmDB-5,30m×0.25mmWAX-10,30m×0.25mmInitial temperature(C)706000ncreasing rate I(C/min)Final temperature I (C)Increasing rate II(C/min)Final temperature(°C270270240Time hold (min)6Carburetor temperature(C)250240He(ml/min)MSEl. 70 eVEL 70eVEL 70ev. full scanScanning mass range(u)40-50040-50Scanning time(s)中国煤化工CNMHGYan et al. /J Zhejiang Univ SCI 2004 5(12): 1554-15641557Fig 1 Schematic of the tubular furnac1: distilled water, 2: dichloromethane, 3: XAD-2 adsorbent, 4: thermocouple, 5: heater,6: ceramic boat, 7: quartz tube, 8: handspike, 9: flow meter, 10: gas container, 11: control panelwas weighed accurately in a ceramic boat. Bottle 3 Flow rates of hydrogen(H2), air, and nitrogen(N2)was filled with XAD-2 adsorbent to absorb PAHs in were 35, 350, and 45 ml/min respectively. Theflue gas. Conical flask I was filled with distilled injection volume to GC was 1 ulwater and conical flask 2 was filled with diThe seventeen PAHs to be analyzed arehloromethane. After the combustion experiment Naphthalene(NaP, 50 pg), Acenaphthylene (AcPywas completed, the distilled water contained in 10 pg), Acenaphthene(AcP, 10 pg), Fluorene(Flu,flask 1 was extracted with dichloromethane as 10 pg), Phenanthrene(Phe, 10 pg), Anthracenesolvent. The extraction solution and the XAD-2 (AnT, 10 pg), Fluoranthene( Fla, 5 pg), Pyrene(Pyadsorbent contained in bottle 3 were both extracted 5 pg), Benzo[a]anthracene(BaA, 5 pg), Chrysenefor 20 hours in a Soxhlet apparatus and concen- (Chr, 5 pg), Benzo[b] fluoranthene(BbF, 10 pg),trated to 5 ml by a rotary evaporator at a tempera- Benzo[k]fluoranthene(BkF, 10 pg), Benzo[e]pyreneture of 40C. The condensate was pretreated for (BeP, 10 pg), Benzola]pyrene (BaP, 10 pg),separation before it was analyzed by using a gas Indeo[123-c, d]pyrene (IND, 50 pg), Dibenzla, hchromatography (GC); it was considered as PAHs anthracene (DBA, 50 pg), Benzo[g, h, i]perylenein flue gas. The rest of the materials in the ceramic BghiP, 50 pg). Figures in the brackets are the sen-boat after combustion was also extracted as above sitivities of the gc for pahs detection Substanceand considered as pahs in residuequalitative determination was performed based onretention times, substance quantitative determina-GC analysis condition for coal combustion tion was performed using the external standardsamplpesmethod. a mixture of 1 7 pahs standards was obGC analysis of the combustion products was tained from the Cambridge Isotope Laboratoryperformed using a ThermoQuest/Trace2000 system (serial number: ES-8032, concentration: 100+10equipped with a flame-ionization detector(FID).a ug/ml, solvent: toluene)quartz capillary column DB-5(30 mx0. 25 mmx0. 25 um) was used. Initial column temperature was70C, heated up to the final temperature I of 180C RESULTS AND DISCUSSIONat a rate of 3C/min. The rate was changed to 10C/min up to the final temperature II of 280C, and PAHs content in five bituminous coalskept at this point for 20The fid teThe organic components of the five bitumiperature was 280 C. Boil offperature was 250 nous coals determined by the solvent extractionoC, the flow rate of the helium(He) carrier gas was method(SY51100ble 3. theI mI/min, the mode of sample entrance was spitless. results showed中国煤化工of the fiveCNMHG1558Yan et al. /J Zhejiang Univ SC/ 2004 5(12): 1554-1564us coals tested were aromatic and polar combustion, with increasing volatiles in coal, PAHsstructures. Aliphatic structures were the minor content also increased to about 26%, then decreasedcomponents in these coals(about 10%0-20%)slightly at higher volatile content. As was also truePAHs distribution by ring number and the total for the fixed carbon, PAHs content decreased withTEQ value of the five coals tested are listed in increasing(H/C)mTable 4. The most abundant Pahs were 5- and6-rings PAHs. The total TEQs of the bituminous PAHs formation from coal combustion andcoals tested were very similar(1.3-1. 6 ug/g)except comparision with PAHs in raw coalfor the Hongyan coal, which had much lower totalDatong and Yanzhou bituminous coal wereTEQ 0.62 ug/g) than those of the other four coals. burned in a tubular furnace(Fig. 1)at a temperatureThe Pahs content in the five bituminous coals of 800 oC with a residence time of 30 minutestested was under10 ug/gPAHs emissions from coal combustion were comCorrelations of PAHs in raw coal with dif- pared with those existing in the raw coal. Table 5ferent coal components are shown in Fig. 2. Volatiles shows that total PAHs emission from combustionare the important sources for PAHs formation during are much higher than those existing in the raw coalTable 3 Distribution of aliphatic hydrocarbons, aromatic hydrocarbons and polar compounds inbituminous coalCoal originAliphatic hydrocarbons (%) Aromatic hydrocarbons(%)Polar compounds(%)13.6040.5840.6952.2230.8841.08Datun11.3545.3943.26Table 4 PAH TEQ and distribution by ring numbers of bituminous coal (ug/g)Coal origin Two-rings Three-rings Four-rings Five-rings Six-ringsTotal TEQ0.00234291.0500904193339382.1423961.102886Zaozhuang0.00397851.20174920.99330581.97890691.6570118Yanzhou0.00292110.70818870.93661541.69530021.5880460.00278620.218l810.06580040.61972510.59156930.62010.00469770.18236780.1643921.36880661.19002911.312737Volatiles (%Fig2 Correlations of PAH in raw coal with differetH中国煤化工(a)PAHs concentration vs volatiles in coals;(b) PAHs concentraCNMHGYan et al. /J Zhejiang Univ SC/ 2004 5(12): 1554-15641559PAHs contents in raw coal contribute little to PAHs whereas two-ring Pahs are the least abundant atemissions from coal combustion. These results also combustion temperature of 600C, above whichsuggested that the coal structure had very little relatively more three- and four-ring PAHs areinfluence on PAHs emissions from coal combus- formed because of the breaking up of the C-C bondstionin the large aromatic hydrocarbons that producerelatively smaller fragments. PAHs in the residueEffects of temperature on PAHs emission from and those in the flue gas, increased with increasingDatong coal combustioncombustion temperature. At higher temperaturesTemperature is an important parameter in coal PAHs formed through the reactions of synthesiscombustion. Bituminous coal was burned at 100C and polymerization of small molecules, while theinterval from 600C to 1000C in our experiments. total PAHs produced from combustion decreasedPAHs produced from coal combustion at different because of more effective combustion. Two com-temperatures showed a single peak trend(Fig 3 ). petitive reactions occur during combustion, PAHsThe highest PAHs emission was at 800C, below formation and PAHs oxidation. Therefore, thewhich, most of the pahs were formed from thamounts of pahs formed decrease when the tempyrolytic processperature increases above 800C. Fig 4 shows thatCondensed aromatic and hydroaromatic units two-and three-ring PAHs increase from 600C toin bituminous coals are connected by either short 800C because decomposition of multi-ring matteralkyl bridges, or ether linkages. Coal contains 80% produces PAHs with fewer rings From 800C toof the carbon as vitrinite(Berkowitz, 1985). Upon 1000C they both decrease, because they are deheating, weaker C-C bonds in the virtinite macerals stroyed through more effective combustionbegin to break. At low temperatures, the mostormation of four- and five-ring PAHsabundant PAHs released are the multi-ring PAHs changed greatly with increasing combustion tem-(six-ring PAHs especially) are the most abundant, perature Four-and five-ring PAHs can be burnedTable 5 ratios of pahs from combustion with pahs in raw coal4Flue gas57.626.6l19.924.735.427.7155.3Flue ga2474.724.427.511.219.5Residue4937.250.835.8250口一 Total1102-rin6-rings10000001000Fig 3 Effect of the combustion temperature on theFig 4 Distribut中国煤化工 g numbertotal pahs emissionat the differentCNMHG1560Yan et al. Zhejiang Univ SC/ 2004 5(12): 1554-1564or decomposed to compounds with lower number 80% of the total chloride released at 400 C as hClrings;and the deep pyrolysis of coal and the de- And the reaction atmosphere has little influence oncomposition of higher ring number compounds can chloride emission. The combustion rates of chloproduce more PAHs. Six-ring PAHs decrease as rinated hydrocarbons are slower than those of thecombustion temperatures increases from 600C to non-chlorinated hydrocarbons, and as the sooting1000C. In addition, decrease of PAHs formation tendency is also high, there will be two flame zonesabove 900C is due to the condition of pyrolysis because of the C-Cl bond is weaker than the C-Creaching maximum, when the products of pyrolysis bond (bose et al., 1983)can be completely combusted to CO2 and H2OFig 6 shows that PAHs emission decrease asTherefore, when the temperature is over 900C, the chlorine content in coal increases for both pyrolysiscombustion is almost completedand combustion cases and that some Pahs areFig 5 of the distributions of PAHs in flue gas converted into chlorinated aromatic compoundsand in residue shows that at 600 C concentration during the pyrolysis and combustion processesof two-ring PAHS in flue gas is much higher than There may be significant influence of oxygen onthat in the residue. The distribution of the three-ring PAHs formation when coal is burned in air. In adPAHs is nearly the same as that of the two-ringdition, when the coal chlorine content changes, thePAHS. With increasing temperature, the two- and amounts of the three-, four-and five-ring PAHsvary significantly, while the amounts of two-andthree-ring PAHs decrease in flue gas, while theyincrease in residue in the deep pyrolysis process of sIx-ring PAHs show very little variation. As thehigh reactivities of the three-, four- and five-ringcoal, so that the ratio of PAHs in flue gas to PAHs PAHs, these PAHs may be more easily substitutedin residue decreases. Most of the six-ring PAHs are by chlorine to form chlorinated compounds. TEQsin residue at low temperature. With increasing of the PAHs produced from coal combustion andtemperature, SIX-ring PAHs in the flue gas increase from pyrolysis are shown in Fig. 7. Similar to PAHsbecause of the synthesis reactionemission, the tEQ values of PAHs from pyrolysisare higher than those from combustion. tEQ valuedecreases with increasing coal chlorine contentthe combustion case, and there is no specific trend3-ringsin tEQ value in the pyrolysis case. It can be seenfrom Fig 8 and Fig9 that in inert atmosphere, PAHsformation in the fluepyrolysis, and as a result, PAHs formation in flue9001000PAHs emission from the combustion of datongcoal with copperFig 5 Distributions of PAHs in flue gas and residueCopper was mixed with Datong coal and thenat different combustion temperaturesthe mixture was burned in a tubular furnace. Themass ratio of( Cu/Coal)m was 1: 100. Coal combusEffect of chlorine content in coal on pahs tion tests were conducted at 600-1200oC. Table 6emissionand Fig. 10 show the results of the PAHs emissionThree kinds of bituminous coals with different tests. Fig 10 shows two formation peaks with in-chlorine contents were tested in the present study. creasing temperature. The first maximum peak is atChloride in coal begins to release as hydrogen 800C, whicho the temperature point ofchloride(hci) at temperature of 200C, with about maximum PAF中国煤化工 ddition ofCNMHGYan et al. /J Zhejiang Univ SCI 2004 5(12): 1554-1564Coal combustion in△- Coal pyrolysis in N21500000000a- Coal combustion in airCoal pyrolysis in N3006009001200hlorine content(×105)Chlorine content(x10)Fig 6 Influence of chlorine content on PAHs emisFig 7 PAHs TEQ from coal pyrolysis and combussion from coal pyrolysis and combustion316x10- Chloride content in coal480x10-2 Chloride content in coal10- Chloride content in coal60 La 1100x10- Cholride content in coal10 Chloride content in coal10 Cholride content in coalIen.Fig 8 PAHs distribution in flue gas of coal pyrolysisFig 9 PAHs distribution in residue of coal pyrolysisTable 6 PAHs emission from combustion of coal with addition of copper(ug/g)NaPN DN DN DN DAcHyN D0.014N D0.005N DN D0.116ND0.154N DN DN DN DND0.035N D4.9974.49913.7100.3073.1560.455Ant0.1500.0140.2762.1479.22115.0490.2922.08110.0002.003Pyr2.0630.0620.8336.0081.940BaA170819.5976.3871.6150.2961.8l50.3372.5082.7161.928Bep0.871BaP1.85521.6680.7634.0028.6312,147INDN DN DN D3.297N D0.30N DDBAN DN DN D0.684N DN DN DbghiPN DN DN D0.620N D20.52435.771136.5557.963H中国煤化工20CNMHG1562Yan et al. /J Zhejiang Univ SC/ 2004 5(12): 1554-1564copper in the coal. The second maximum peak is at 1: 100 ratio of(Cu/Coal)m results in least PAHs1100C, which is higher than the boiling point of formation at the two combustion temperaturescopper. As discussed earlier, there are two sug- Except for some PAHs with low number of ringsgested main mechanisms for PAHs formation. The individual PAHs concentration is somewhat highinitial ring formation can occur through: hydrogen Cupric oxide was mixed with coal and then theabstraction, C2H2 addition, and then ring closure; or mixture was burned. The highest PAHs emissionC2H2 addition on an existing ring. There is also a was observed at a combustion temperature of 1000possibility of the reaction of two CsHs radicals to C(Fig. 12). Fig 13 shows that the four-ring PAHsform two fused rings. It is the temperature that are much higher in concentration than those ofdecides which mechanism is the dominant pathway. other PAHs at 1000C. The concentrations of otherMetal can act as an active center and promote PAHs PAHs with more or fewer rings are peaked at 900formation. It can be seen from Fig. I I that the 4-and C. Table 9 shows Fla and Pyr are the two Pahs5-rings PAHs occur at highest concentrations in the with the highest concentrationsemissions. At low temperature of 600C, Phe,aGenerally, Pahs formation from coal comthree-ring PAH occurs at the highest concentration. bustion with the addition of copper is lower thanWith increasing temperature, the concentration of that from the case of addition of cupric oxidethe PAHs with more rings increase. It can beThe TEQs of PAHs from coal combustion withsuggested that copper may promote PAHs forma- the additions of copper and cupric oxide are listedtion at high temperatures, especially the multi-ring in Table 9. The tEQs from coal combustion withthe addition of copper are of the same magnitude asIt can be seen from Table 7 and Table 8 that the those with the addition of cupric oxide2120a -4-rings三1009--5-rings00001060070080090010001100120000700800900100011001200Temperature(C)Temperature(°C)Fig 10 The influence of temperature on PAHs emissions Fig 11 PAHs distributions by ring number from combusfrom combustion of coal with addition of copper in coal tion of coal with addition of copper in coal1506007008009001000110012006007008009001000I1001200Temperature(°C)Fig 12 The influence of combustion temperature on PAHsemission from combustion of coal with addition of cupric Fig 13 PAHsoxidetion of coal witYH史题Yan et al. /J Zhejiang Univ SCI 2004 5(12): 1554-1564Table 7 PAHs emission from combustion of coal with addition of different ratio of copper(ug/g)Temperature(°C800Cu/Coal)mNaPNDNDNDN DN DN DN DAcPN DN D16.5100.010AnT0.006174660.0080.01920.957Py21.53926.615BaA7.2714.5048.11lChr7.7341746614712.2041BbF13.5640.95BkF6.3100.3590.287BeP5.64313.1413.5284.854Bap7.97013.3545.0765.15597.185ND12.524N, DDBABghiP11.07780.404127.544200.0776995078.687D. -not detectedTable 8 PAHs emission from combustion of coal with addition of cupric oxide(ug/g)Abbr.(°C60080090010001200N DN, DN, DN D0.034N DN D11.5261.055AcPN DND0.254N DN DN D0.0461.6795.714104333.7420.0364.6848.13422.67324.7840.3121492Ant1.18720.4060.17120.3917.04439.54641.745118.7655.1564.36221.10244.9100.3626.978BaA2.6396.96010.28451.06414.9553.466Ch3.1674.9688.381104268.236BbF0.9943.7510.8270.1451.559BkF0.5660.32810.9720.3260.9673.8293.58859607.1013.6080.4582.6753.51710.2450.4610.5342.64NDN DN D7.081NDNDN DN D1.891N DN D0.033BghiPN DN DTotal42.99455.041199.614251.18549.9136.989N D, -not detected中国煤化工CNMHG1564Yan et al. /J Zhejiang Univ SC/ 2004 5(12): 1554-1564Table 9 PAHs tEQ from combustion of coal with ad18:125-127(1dition of copper and cupric oxideiu, K L, Han, w.J., Pan, W.P., Riley, J.T., 2001. PolTemperature(C) CoalCu(ug/g) Coal+ Cuo(ug/g)cyclic aromatic hydrocarbon(PAH)1.8471.952coal-fired pilot FBC system. Journal of Hazardous2.4013.624Materials. B84: 175-184.904Mastral, A M, Callen, M., 2000. A review on polycyclicaromatic hydrocarbon(PAH) emissions from energygeneration. Environ. Sci. TechnoL, 34(15): 3051-3057Mastral, A M., Callen, M, Murillo, R, Garcia, T, 1998aassessment of pah emission as a function of coal3.2390.830combustion variables in fluidised bed 2: air excesspercentage. Fuel, 77(13): 1513-1516CONCLUSIONMastral.Am. callen.M. Murillo, R.1998b, Assessmentof pah emissions as a function of coal combustionPAHs formation in early stage of pyrolysisvariables. Fuel, 77(13): 1533-1536more innportant in the whole coal combustionMastral, A.M., Callen, M., Murillo, R, Garcia T, Vinas M.process. The combustion temperature has great99. Influence on Pah emissions of the air flow inAFB coal combustion Fuel. 78: 1553-1557influence on pahs emission pahs formationMastral. A.M.. Callen. M.S., Garcia. T. 2000. Toxic or-process can be divided into two stages: low temganic emissions from coal combustion. Fuel Procperature stage and high temperature stage. Atessing Technology, 67: 1-10temperature of 800C, PAHs concentrations reach Mastral, A M. Garcia, T, Callen, M.S., Lopez, JMtheir maximum. In the low temperature stageMurillo, R, Navarro, M.V., 2001. Effects of limestonePAHs formation is from coal pyrolysis, but in theon polycyclic aromatic hydrocarbon emissions duringcoal atmospheric fluidized bed combustion Energy chigh temperature stage, PAHs formation is due toFuels,15:1469-1474the synthesis of small hydrocarbons. As chlorine Miller, J., 1994. Emissions of organic hazardous air polcontent of coal increases the amounts of pahlutants from the combustion of pulverized coal in aproduced from combustion of coal in air and frommall-scale combustor Environ Sci. Technol. 28pyrolysis of coal in N2 decrease, probably because1150-1158f the formation of chlorinated aromatic com-Ni. M.J.. You, X.F.Li.X.D.. Yin, X.F. Cao.ZY. YanJ H, Cen, K.F., 2003. Study of PAHs formation frompounds. Copper and cupric oxide additives promotedifferent kinds of coal combustion process. PowerPAHs formation during coal combustion, espeEngineering, accepted (in Chinese)cially the multi-ring PAHsSai, X C, 1995. The pollution of PAH. Environment Pro-tection, 10: 31-33ReferencesSolomon, P.R., Hamblen, D.G., Carangelo, R M, Serio,Berkowitz, N, 1985. The Chemistry of Coal. Coal ScienceM.A., Deshpande, G.V., 1988. General model of coaland Technology 7, Elsevierdevolatilization. Energy Fuels, 2: 405-422Bose D Senkan M., 1983. On the combustion of chlorin- wey, M.Y., Chao. C.Y., Wei, M.C., Yu, L.J., Liu, ZSated hydrocarbons I Trichloroethy lene, Combust. Sci2000. The influence of heavy metals on partitioning ofand Tech,35:187-292PAHs during incineration Journal of Hazardous maFeitelberg, A S, Longwell, J.P., Sarofim, A F, 1993. Metalterials. 77A: 77-87enhanced soot and pah formation Combustion andWornat, M.J., Sarofim, A.F., Longwell, J.P., 1987. Changesin the degree of substitution of polycyclic aromaticameLedesma. E B. Kalish, M.A. Nelson. P F,. Wornat. M.Jcompounds from pyrolysis of a high-volatile bituminous coal. Energy Fuels, 1: 431-437Mackie. JC. 2000. Formation and fate PAH during Yan, R, Zhu, H.J., Liu, H, Yi, H L, 1996. Studies onpyrolysis and fuel-rich combustion of coal primary tarFuel.79:1801-l814composition of productcombustion of henaLi, X D, Fu, G, You, X.F., Yan, J H, 2003. Study of PAHsformation from combustion of different coal typeAnalysis Laboratory, 15Journal of Engineering for Thermal Energy and Power,H中国煤化工CNMHG