稀释气体对天然气掺甲醇裂解气定容预混燃烧的影响
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摘要
用H_2、CO体积比为2∶1的混合气来模拟甲醇裂解气(dissociated methanol,DM),在温度343K、压力0.3MPa的条件下基于燃烧压力、最高燃烧压力、爆炸指数及临界半径等参数研究了CH_4(60%)-DM(40%)预混气在添加稀释气体(N_2、CO_2)后的燃烧的变化情况。在不添加稀释气体的条件下,进行了同样初始温度和压力下的天然气(100%/60%/20%)-甲醇裂解气(0%/40%/80%)-空气预混燃烧的对比试验。结果表明:甲醇裂解气能加快压力上升,促进燃烧,缩短燃烧持续期,加速火焰胞状结构的出现,但在化学计量比及附近会降低最高燃烧压力;稀释气体则有降低最高燃烧压力和爆炸指数等抑制燃烧的作用,其中CO_2对燃烧的抑制作用强于N_2。
A mixture of H_2and CO in volume ratio of two to one was used to simulate dissociated methanol(DM).The combustion of pre-mixture of natural gas(60%)and DM(40%)with diluent gases N_2and CO_(2 )was analyzed at the initial temperature of 343Kand the initial pressure of 0.3MPa in terms of combustion pressure,the maximum combustion pressure,explosion index and critical radius.The comparison of the combustions of different pre-mixtures of natural gas(100%,60%and 20%),DM(0%,40%and 80%)and air were experimentally conducted at the same initial temperature and pressure without diluent gases.The results show that DM has the function of accelerating pressure rise,promoting combustion,shortening combustion duration and advancing the formation of cellularity,but it will also reduce the maximum combustion pressure at and around the stoichiometric ratio,while the diluent gases have the opposite effects on combustion,such as decreasing the maximum combustion pressure and explosion index.In addition,CO_2is stronger than N_2in the suppression of combustion.
A mixture of H_2and CO in volume ratio of two to one was used to simulate dissociated methanol(DM).The combustion of pre-mixture of natural gas(60%)and DM(40%)with diluent gases N_2and CO_(2 )was analyzed at the initial temperature of 343Kand the initial pressure of 0.3MPa in terms of combustion pressure,the maximum combustion pressure,explosion index and critical radius.The comparison of the combustions of different pre-mixtures of natural gas(100%,60%and 20%),DM(0%,40%and 80%)and air were experimentally conducted at the same initial temperature and pressure without diluent gases.The results show that DM has the function of accelerating pressure rise,promoting combustion,shortening combustion duration and advancing the formation of cellularity,but it will also reduce the maximum combustion pressure at and around the stoichiometric ratio,while the diluent gases have the opposite effects on combustion,such as decreasing the maximum combustion pressure and explosion index.In addition,CO_2is stronger than N_2in the suppression of combustion.
引文
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[3]韩敏超,艾育华,陈正,等.不同预热温度下H2/CO/O2/CO2的层流火焰传播特性[J].工程热物理学报,2016,37(1):189-193.HAN M C,AI Y H,CHEN Z,et al.Study on laminar flame characteristics of H2/CO/O2/CO2 mixtures at different preheating temperatures[J].Journal of Engineering Thermophysics,2016,37(1):189-193.
[4]HU X,YU Q,LIU J.Chemical effect of CO2on the laminar flame speeds of oxy-methane mixtures in the condition of various equivalence ratios and oxygen concentrations[J].International Journal of Hydrogen Energy,2016,41(33):15068-15077.
[5]CAI X,WANG J,ZHANG W,et al.Effects of oxygen enrichment on laminar burning velocities and Markstein lengths of CH4/O2/N2flames at elevated pressures[J].Fuel,2016,184:466-473.
[6]TANAKA T,AZUMA T,EVANS J A,et al.Experimental study on hydrogen explosions in a full-scale hydrogen filling station model[J].International Journal of Hydrogen Energy,2007,32(13):2162-2170.
[7]暴秀超,刘福水,陈超.氢气定容燃烧的实验研究[J].爆炸与冲击,2009,34(5):580-585.BAO X C,LIU F S,CHEN C.Experimental study on hydrogen constant volume combustion[J].Explosion and Shock Waves,2009,34(5):580-585.
[8]韩志强,钱云寿,田维,等.稀释率与温度耦合作用对天然气预混燃烧等量影响研究[J].兵工学报,2018,39(5):998-1005.HAN Z Q,QIAN Y S,TIAN W,et al.Research on equivalent effects of dilution ratio and temperature on premixed combustion of natural gas[J].Acta Armamentarii,2018,39(5):998-1005.
[9]BJERKETVEDT D,BAKKE J R,WINGERDEN K V.Gas explosion handbook[J].Journal of Hazardous Materials,1997,52(1):1-150.
[10]ZUO Z N,PEI Y Q,QIN J,et al.Impact of dissociated methanol addition on premixed toluene reference fuel-air mixtures in a constant-volume chamber[J].International Journal of Hydrogen Energy,2018,43(13):6745-6755.
[11]张烜,黄佐华,喻武,等.高温高压条件下甲醇裂解气-空气-稀释气层流火焰传播速度和马克斯坦长度研究[J].内燃机学报,2010,28(3):214-220.ZHANG X,HUANG Z H,YU W,et al.Experimental study on laminar burning velocity and Markstein length of dissociated methanol-air-diluent mixtures at elevated temperatures and pressures[J].Transactions of CSICE,2010,28(3):214-220.
[12]SHANG R,ZHANG Y,ZHU M,et al.Laminar flame speed of CO2 and N2 diluted H2/CO/air flames[J].International Journal of Hydrogen Energy,2016,41(33):15056-15067.
[13]胡二江.天然气-氢气混合燃料结合EGR的发动机和预混层流燃烧研究[D].西安:西安交通大学,2010.
[14]ZHANG X,HUANG Z,ZHANG Z,et al.Measurements of laminar burning velocities and flame stability analysis for dissociated methanol-air-diluent mixtures at elevated temperatures and pressures[J].International Journal of Hydrogen Energy,2009,34(11):4862-4875.
[15]TANG C,HUANG Z,JIN C,et al.Explosion characteristics of hydrogen-nitrogen-air mixtures at elevated pressures and temperatures[J].International Journal of Hydrogen Energy,2009,34(1):554-561.
[16]KWON O C,ROZENCHAN G,LAW C K.Cellular instabilities and self-acceleration of outwardly propagating spherical flames[J].Proceedings of the Combustion Institute,2002,29(2):1775-1783.
[17]贾若愚,秦静,裴毅强,等.甲醇裂解气对天然气-空气预混层流燃烧特性的影响[J].内燃机学报,2018,36(1):51-59.JIA R Y,QIN J,PEI Y Q,et al.Effects of dissociated methanol gas addition on laminar burning characteristics in methane-air premixed flames[J].Transactions of CSICE,2018,36(1):51-59.