煤在加压流化床富氧燃烧条件下的碳转化规律
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摘要
在15 kW加压流化床富氧燃烧实验台上,进行了内蒙古烟煤在850～900℃下的加压富氧燃烧实验,研究了压力为0. 1～0. 4 MPa、空气和21%～30%氧浓度的O_2/CO_2气氛下燃烧的碳转化规律.研究结果表明:稳态富氧燃烧条件下,加压流化床富氧燃烧实验台干烟气中CO_2浓度均超过90%.提高燃烧压力有利于提高碳转化率和CO_2生成率,有利于降低CO生成率.在压力0. 1～0. 3 M Pa范围内,CO_2生成率随着压力的增加基本呈线性递增关系,从85%左右增加到93%左右.进一步增加压力,CO_2生成率逐渐趋于平稳,并保持在较高水平.在压力为0. 4 MPa条件下,CO_2生成率增加到95%左右.提高O_2/CO_2气氛的氧浓度能够提高碳转化率和CO_2生成率,但是随着压力的提高,氧浓度对碳转化率和CO_2生成率的影响减小.
A combustion experiment of the Inner Mongolia bituminous coal was conducted at furnace temperature from 850 to 900 ℃ in a 15 kW pressurized oxy-fuel fluidized bed. The carbon conversion rules were investigated in the pressure range from 0. 1 to 0. 4 MPa,and in the atmosphere between air and O_2/CO_2 mixtures. The results show that the CO_2 concentration at the outlet of the pressurized fluidized bed is over 90% under the steady condition of oxy-fuel combustion. Increasing combustion pressure can increase the carbon conversion rate and reduce the CO_2 generation rate. The CO_2 generation rate is linearly increased from about 85% to 93% with an increase in pressure from0. 1 to 0. 3 MPa,while the CO_2 generation rate reaches 95% at 0. 4 MPa. The CO_2 generation rate gradually levels off and stays at a high level as the pressure further increases. The carbon conversion rate and the CO_2 generation rate increase with the increase of O_2 concentration. However,the impact of O_2 concentration is weakened with the increase of the combustion pressure.
A combustion experiment of the Inner Mongolia bituminous coal was conducted at furnace temperature from 850 to 900 ℃ in a 15 kW pressurized oxy-fuel fluidized bed. The carbon conversion rules were investigated in the pressure range from 0. 1 to 0. 4 MPa,and in the atmosphere between air and O_2/CO_2 mixtures. The results show that the CO_2 concentration at the outlet of the pressurized fluidized bed is over 90% under the steady condition of oxy-fuel combustion. Increasing combustion pressure can increase the carbon conversion rate and reduce the CO_2 generation rate. The CO_2 generation rate is linearly increased from about 85% to 93% with an increase in pressure from0. 1 to 0. 3 MPa,while the CO_2 generation rate reaches 95% at 0. 4 MPa. The CO_2 generation rate gradually levels off and stays at a high level as the pressure further increases. The carbon conversion rate and the CO_2 generation rate increase with the increase of O_2 concentration. However,the impact of O_2 concentration is weakened with the increase of the combustion pressure.
引文
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[26]Bu C S,Gómez-Barea A,Chen X P,et al.Effect of CO2 on oxy-fuel combustion of coal-char particles in a fluidized bed:Modeling and comparison with the conventional mode of combustion[J].Applied Energy,2016,177:247-259.DOI:10.1016/j.apenergy.2016.05.108.
[27]Sher F,Pans M A,Sun C G,et al.Oxy-fuel combustion study of biomass fuels in a 20 kWth fluidized bed combustor[J].Fuel,2018,215:778-786.DOI:10.1016/j.fuel.2017.11.039.
[28]Jin X D,Zhou Y G,Zheng S K.Numerical investigation of different effects of carbon dioxide properties and carbon monoxide oxidation on char particle combustion in actual and fictitious O2/CO2 environments[J].Fuel,2018,217:59-65.DOI:10.1016/j.fuel.2017.12.040.
[29]Bürkle S,Dreizler A,Ebert V,et al.Experimental comparison of a 2D laminar diffusion flame under oxyfuel and air atmosphere[J].Fuel,2018,212:302-308.DOI:10.1016/j.fuel.2017.10.067.
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[2]Zebian H,Rossi N,Gazzino M,et al.Optimal design and operation of pressurized oxy-coal combustion with a direct contact separation column[J].Energy,2013,49:268 278.DOI:10.1016/j.energy.2012.11.013.
[3]Gopan A,Kumfer B M,Axelbaum R L.Effect of operating pressure and fuel moisture on net plant efficiency of a staged,pressurized oxy-combustion power plant[J].International Journal of Greenhouse Gas Control,2015,39:390-396.DOI:10.1016/j.ijggc.2015.05.014.
[4]Xia F,Yang Z W,Adeosun A,et al.Pressurized oxycombustion with low flue gas recycle:Computational fluid dynamic simulations of radiant boilers[J].Fuel,2016,181:1170-1178.DOI:10.1016/j.fuel.2016.04.023.
[5]韩冬,段伦博,段钰锋,等.增压O2/CO2燃烧热力系统建模及压力优化[J].中国电机工程学报,2014,34(5):756-762.DOI:10.13334/j.0258-8013.pcsee.2014.05.007.Han D,Duan L B,Duan Y F,et al.Simulation and optimization of pressurized oxy-fuel combustion system[J].Proceedings of the CSEE,2014,34(5):756-762.DOI:10.13334/j.0258-8013.pcsee.2014.05.007.(in Chinese)
[6]Zebian H,Mitsos A.Pressurized OCC(oxy-coal combustion)process ideally flexible to the thermal load[J].Energy,2014,73:416-429.DOI:10.1016/j.energy.2014.06.031.
[7]刘前鑫,李大骥,时铭显,等.增压流化床联合循环发电技术[M].南京:东南大学出版社,1998:107-124.
[8]Roy B,Bhattacharya S.Combustion of single char particles from Victorian brown coal under oxy-fuel fluidized bed conditions[J].Fuel,2016,165:477-483.DOI:10.1016/j.fuel.2015.10.099.
[9]Sadegh Seddighi K,Pallarès D,Normann F,et al.Carbon monoxide formation during oxy-fuel-fired fluidizedbed combustion[J].Energy&Fuels,2013,27(4):2275-2282.DOI:10.1021/ef3021393.
[10]Sher F,Pans M A,Sun C G,et al.Oxy-fuel combustion study of biomass fuels in a 20 kWth fluidized bed combustor[J].Fuel,2018,215:778-786.DOI:10.1016/j.fuel.2017.11.039.
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[12]Li H Y,Li S Y,Ren Q Q,et al.Experimental results for oxy-fuel combustion with high oxygen concentration in a 1 MWth pilot-scale circulating fluidized bed[J].Energy Procedia,2014,63:362-371.DOI:10.1016/j.egypro.2014.11.039.
[13]毛玉如,方梦祥,骆仲泱,等.循环流化床富氧燃烧技术的试验研究[J].锅炉技术,2004,35(6):27-31.DOI:10.3969/j.issn.1672-4763.2004.06.007.Mao Y R,Fang M X,Luo Z Y,et al.Experimental study on oxygen enriched combustion technology on circulating fluidized bed test-facility[J].Boiler Technology,2004,35(6):27-31.DOI:10.3969/j.issn.1672-4763.2004.06.007.(in Chinese)
[14]段伦博,周骛,屈成锐,等.50kW循环流化床O2/CO2气氛下煤燃烧及污染物排放特性[J].中国电机工程学报,2011,31(5):7-12.DOI:10.13334/j.0258-8013.pcsee.2011.05.009.Duan L B,Zhou W,Qu C R,et al.Combustion and pollutant emission characteristics of coal in a 50 kWcirculating fluidized bed under O2/CO2 atmosphere[J].Proceedings of the CSEE,2011,31(5):7-12.DOI:10.13334/j.0258-8013.pcsee.2011.05.009.(in Chinese)
[15]Duan Y Q,Duan L B,Anthony E J,et al.Nitrogen and sulfur conversion during pressurized pyrolysis under CO2 atmosphere in fluidized bed[J].Fuel,2017,189:98-106.DOI:10.1016/j.fuel.2016.10.080.
[16]Li L,Duan Y Q,Duan L B,et al.Flow characteristics in pressurized oxy-fuel fluidized bed under hot condition[J].International Journal of Multiphase Flow,2018,108:1-10.DOI:10.1016/j.ijmultiphaseflow.2018.06.020.
[17]Bu C S,Pallarès D,Chen X P,et al.Oxy-fuel combustion of a single fuel particle in a fluidized bed:Char combustion characteristics,an experimental study[J].Chemical Engineering Journal,2016,287(3):649-656.DOI:10.1016/j.cej.2015.11.078.
[18]Bu C S,Gómez-Barea A,Leckner B,et al.Oxy-fuel conversion of sub-bituminous coal particles in fluidized bed and pulverized combustors[J].Proceedings of the Combustion Institute,2017,36(3):3331-3339.DOI:10.1016/j.proci.2016.08.075.
[19]Li L,Duan L B,Zeng D,et al.Ignition and volatile combustion behaviors of a single lignite particle in a fluidized bed under O2/H2 O condition[J].Proceedings of the Combustion Institute,2018,44-1-44-9.DOI:10.1016/j.proci.2018.05.038.
[20]应芝,张彦威,葛立超,等.加压O2/CO2气氛下煤粉着火特性的实验研究[J].中国电机工程学报,2013,33(8):44-49,9.DOI:10.13334/j.0258-8013.pcsee.2013.08.010.Ying Z,Zhang Y W,Ge L C,et al.Experimental research on ignition characteristics of pulverized coal under pressurized O2/CO2 atmosphere[J].Proceedings of the CSEE,2013,33(8):44-49,9.DOI:10.13334/j.0258-8013.pcsee.2013.08.010.(in Chinese)
[21]胡海华,段伦博,陈晓平,等.增压O2/CO2气氛下煤燃烧特性实验研究[J].燃料化学学报,2014,42(4):408-413.Hu H H,Duan L B,Chen X P,et al.Experimental investigation on pressurized coal combustion characteristics under O2/CO2 atmosphere[J].Journal of Fuel Chemistry and Technology,2014,42(4):408-413.(in Chinese)
[22]Wang C B,Lei M,Yan W P,et al.Combustion characteristics and ash formation of pulverized coal under pressurized oxy-fuel conditions[J].Energy&Fuels,2011,25(10):4333-4344.DOI:10.1021/ef200956q.
[23]Lasek J A,Janusz M,Zuwaa J,et al.Oxy-fuel combustion of selected solid fuels under atmospheric and elevated pressures[J].Energy,2013,62(6):105-112.DOI:10.1016/j.energy.2013.04.079.
[24]孙晨亮,章名耀.压力下各种因素对煤粒着火温度的影响[J].燃烧科学与技术,1999,5(3):313-318.Sun C L,Zhang M Y.Effects of various factors on the ignition temperature of coal particles under pressure[J].Journal of Combustion Science and Technology,1999,5(3):313-318.(in Chinese)
[25]Liu H,Zailani R,Gibbs B.Comparisons of pulverized coal combustion in air and in mixtures of O2/CO2[J].Fuel,2005,84:833-840.DOI:10.1016/j.fuel.2004.11.018.
[26]Bu C S,Gómez-Barea A,Chen X P,et al.Effect of CO2 on oxy-fuel combustion of coal-char particles in a fluidized bed:Modeling and comparison with the conventional mode of combustion[J].Applied Energy,2016,177:247-259.DOI:10.1016/j.apenergy.2016.05.108.
[27]Sher F,Pans M A,Sun C G,et al.Oxy-fuel combustion study of biomass fuels in a 20 kWth fluidized bed combustor[J].Fuel,2018,215:778-786.DOI:10.1016/j.fuel.2017.11.039.
[28]Jin X D,Zhou Y G,Zheng S K.Numerical investigation of different effects of carbon dioxide properties and carbon monoxide oxidation on char particle combustion in actual and fictitious O2/CO2 environments[J].Fuel,2018,217:59-65.DOI:10.1016/j.fuel.2017.12.040.
[29]Bürkle S,Dreizler A,Ebert V,et al.Experimental comparison of a 2D laminar diffusion flame under oxyfuel and air atmosphere[J].Fuel,2018,212:302-308.DOI:10.1016/j.fuel.2017.10.067.
[30]Zhang L,Binner E,Chen L G,et al.Experimental investigation of the combustion of bituminous coal in air and O2/CO2 Mixtures:1.Particle imaging of the combustion of coal and char[J].Energy&Fuels,2010,24(9):4803-4811.DOI:10.1021/ef100314k.