H_2S对CH_4着火延迟及还原NO影响的数值模拟
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摘要
为探究硫化氢(H_2S)在常压范围内对甲烷(CH_4)燃烧特性的影响,采用化学动力学软件CHEMKIN-PRO中的0-D和PFR反应器研究H_2S浓度、过量空气系数、压力和温度对CH_4点火延迟及还原NO的影响,并通过敏感性和生成率分析揭示其化学动力学机理.模拟结果表明:H_2S的存在促进活性基团(H,O,OH,HO_2,HO_2和H_2O_2)的生成速率,从而缩短预混气点火延迟时间,且在低温下的影响作用更加明显;预混气点火延迟时间随着过量空气系数的增大而减小;压力增加亦有利于缩短点火延迟时间. H_2S可降低CH_4/H_2S还原NO的温度,主要由于H_2S降低CH_4的反应温度,使还原性基团CH_i在较低温度下产生;但同时H_2S的存在,在一定程度上降低NO的还原效率,且在贫氧气氛中的影响更为显著.
To investigate the effects of hydrogen sulfide(H_2S) on the combustion characteristics of methane(CH_4) in atmospheric pressure range, the 0-D and PFR reactors were adopted in CHEMKIN-PRO chemical kinetics software to investigate the effects of H_2S concentration, excess air coefficient, pressure and temperature on CH_4 ignition delay and NO reduction, meanwhile sensitivity analysis was used to reveal the chemical kinetics mechanism. The modeling results showed that the H_2S could promote the formation rate of active groups(H, O, OH, HO_2, HO_2, H_2O_2), so premixed gas ignition delay time was reduced, and the effect was more obvious at low temperature. The premixed gas ignition delay time is decreased with the increase of excess air coefficient and pressure. The H_2S decreases the CH_4 reaction temperature and reductive group CH_i are generated at lower temperature, so the H_2S decreases the temperature of NO reduction by CH_4/H_2S. But the existing of H_2S reduces NO reduction efficiency to a certain extent, and the effect is more remarkable in fuel-rich atmosphere.
To investigate the effects of hydrogen sulfide(H_2S) on the combustion characteristics of methane(CH_4) in atmospheric pressure range, the 0-D and PFR reactors were adopted in CHEMKIN-PRO chemical kinetics software to investigate the effects of H_2S concentration, excess air coefficient, pressure and temperature on CH_4 ignition delay and NO reduction, meanwhile sensitivity analysis was used to reveal the chemical kinetics mechanism. The modeling results showed that the H_2S could promote the formation rate of active groups(H, O, OH, HO_2, HO_2, H_2O_2), so premixed gas ignition delay time was reduced, and the effect was more obvious at low temperature. The premixed gas ignition delay time is decreased with the increase of excess air coefficient and pressure. The H_2S decreases the CH_4 reaction temperature and reductive group CH_i are generated at lower temperature, so the H_2S decreases the temperature of NO reduction by CH_4/H_2S. But the existing of H_2S reduces NO reduction efficiency to a certain extent, and the effect is more remarkable in fuel-rich atmosphere.
引文
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[3] SHU Yun,WANG Hongchang,ZHU Jinwei,et al.An experimental study of heterogeneous NO reduction by biomass reburning[J].Fuel Processing Technology,2015,132:111.DOI:10.1016/j.fuproc.2014.12.039
[4] ZHAO Jie,WANG Qingcheng,YU Lihui,et al.Influence of the biogas reburning for reducing nitric oxide emissions in an alundum-tube reactor[J].Atmospheric Environment,2016,132:290.DOI:10.1016/j.atmosenv.2016.03.004
[5] SU Sheng,XIANG Jun,SUN Lushi,et al.Application of gaseous fuel reburning for controlling nitric oxide emissions in boilers[J].Fuel Processing Technology,2009,90(3):396.DOI:10.1016/j.fuproc.2008.10.011
[6] SMOOT L D,HILL S C,XU H.NOx control through reburning[J].Progress in Energy and Combustion Science,1998,24(5):385.DOI:10.1016/S0360-1285(97)00022-1
[7] 陈宝明,张忠孝,毕德贵,等.天然气再燃降低NOx排放的热态工业试验研究[J].热能动力工程,2015,30(1):113.CHEN Baoming,ZHANG Zhongxiao,BI Degui,et al.Hot-state industrial experimental study of the reburning of natural gas to reduce NOx emissions[J].Proceedings of the CSEE,2003,23(10):204.DOI:10.16146/j.cnki.rndlgc.2015.01.030.
[8] ALZUETA M U,GLARBORG P,DAM-JOHANSEN K.Low temperature interactions between hydrocarbons and nitric oxide:an experimental study[J].Combustion and Flame,1997,109(1/2):25.DOI:10.1016/S0010-2180(96)00146-0
[9] GLARBORG P,ALZUETA M U,DAM-JOHANSEN K,et al.Kinetic modeling of hydrocarbon/nitric oxide interactions in a flow reactor[J].Combustion and Flame,1998,115(1/2):1.DOI:10.1016/S0010-2180(97)00359-3
[10]SONG Y,HASHEMI H,CHRISTENSEN J M,et al.An exploratory flow reactor study of H2S oxidation at 30-100 bar[J].International Journal of Chemical Kinetics,2017,49(1):37.DOI:10.1002/kin.21055
[11]CHIN H S F,KARAN K,MEHROTRA A K,et al.The fate of methane in a claus plant reaction furnace[J].Canadian Journal of Chemical Engineering,2010,79(4):482.DOI:10.1002/cjce.5450790404
[12]GERSEN S,ESSEN M V,DARMEVEIL H,et al.Experimental and modeling investigation of the effect of H2S addition to methane on the ignition and oxidation at high pressures[J].Energy & Fuels,2016,31(3):2175.DOI:10.1021/acs.energyfuels.6b02140
[13]BONGARTZ D,GHONIEM A F.Impact of sour gas composition on ignition delay and burning velocity in air and oxy-fuel combustion[J].Combustion and Flame,2015,162(7):2749.DOI:10.1016/j.combustflame.2015.04.014
[14]CHEN Z,JU Y.Theoretical analysis of the evolution from ignition kernel to flame ball and planar flame[J].Combustion Theory and Modelling,2007,11(3):427.DOI:10.1080/13647830600999850
[15]PILL M J,TURANYI T,HUGHES K J.Combined mechanisms,Release 3[EB/OL].(2004-10-18)[2018-9-21].http://respecth.hu/.html
[16]TU Yaojie,SU Kai,LIU Hao,et al.Physical and chemical effects of CO2 addition on CH4/H2 flames on a Jet in hot coflow (JHC) burner[J].Energy & Fuels,2016,30(2):1390.DOI:10.1021/acs.energyfuels.5b02499
[17]TURANY T,BERCES T,VAJDA S.Reaction rate analysis of complex kinetic systems[J].International Journal of Chemical Kinetics,1989,21(2):83.DOI:10.1002/kin.550210203
[18]钱琳.煤气再燃还原氮氧化物化学反应动力学的研究[D].哈尔滨:哈尔滨工业大学,2007 QIAN Lin.Chemical kinetics of NOx reduction by reburning with coal-gas.Harbin:Harbin Institute of Technology,2007
[19]WANG Xuebin,TAN Houzhang,NIU Yanqing,et al.Kinetic investigation of the SO2 influence on NO reduction processes during methane reburning[J].Asia-Pacific Journal of Chemical Engineering,2010,5(6):902.DOI:10.1002/apj.420