基于欧拉-欧拉多相流模型对生物质快速热裂解的数值模拟
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摘要
基于欧拉-欧拉多相流方法,采用单步多元反应动力学模型研究了生物质在二维鼓泡流化床反应器中的快速热裂解反应,分析了反应器中颗粒流动、传热以及热裂解产物组成的分布规律。结果表明:气泡的流动有助于气体、石英砂和生物质的混合和热量交换;经过气体的对流换热和石英砂的接触导热,生物质温度迅速升高后发生热裂解,热裂解温度为750～850 K;计算得到的生物油、焦炭和不可冷凝气体的产率分别为59.2%、14.4%和22.1%。
Based on Euler-Euler method, the kinetic model for single-step multi-component reaction was used to study the fast pyrolysis of biomass in a two-dimensional bubbling fluidized bed reactor, with focus on analysis of the particle flow, heat transfer, and the distribution of pyrolysis products in the reactor. Results show that the bubble flow benefits the mixing and heat exchange of gas, quartz sand and biomass particles. Through convective heat transfer with gas and contact heat conduction with quartz sand, the temperature of biomass rises rapidly, following which, fast pyrolysis of biomass occurs, with a pyrolysis temperature lying in 750-850 K, and the calculated yields of bio-oil, char, and non-condensable gas being 59.2%, 14.4% and 22.1%, respectively.
Based on Euler-Euler method, the kinetic model for single-step multi-component reaction was used to study the fast pyrolysis of biomass in a two-dimensional bubbling fluidized bed reactor, with focus on analysis of the particle flow, heat transfer, and the distribution of pyrolysis products in the reactor. Results show that the bubble flow benefits the mixing and heat exchange of gas, quartz sand and biomass particles. Through convective heat transfer with gas and contact heat conduction with quartz sand, the temperature of biomass rises rapidly, following which, fast pyrolysis of biomass occurs, with a pyrolysis temperature lying in 750-850 K, and the calculated yields of bio-oil, char, and non-condensable gas being 59.2%, 14.4% and 22.1%, respectively.
引文
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[3] 李帅,张居兵,朴桂林,等.木质生物质定温热解炭化特性研究[J].动力工程学报,2015,35(6):495-500.LI Shuai,ZHANG Jubing,PIAO Guilin,et al.Study on characteristics of woody biomass isothermal carbonization[J].Journal of Chinese Society of Power Engineering,2015,35(6):495-500.
[4] 文丽华,王树荣,骆仲泱.生物质的多组分热裂解动力学模型[J].浙江大学报(工学版),2015,39(2):247-252.WEN Lihua,WANG Shurong,LUO Zhongyang.Multicomponent kinetic model of biomass pyrolysis[J].Journal of Zhejiang University (Engineering Science),2015,39(2):247-252.
[5] 谢俊,钟文琪,金保昇.可燃固废流化床气化的欧拉-拉格朗日数值模拟[J].工程热物理学报,2014,35(11):2220-2224.XIE Jun,ZHONG Wenqi,JIN Baoshen.Eulerian-Lagrangian simulation of combustible solid waste gasification in a fluidized bed[J].Journal of Engineering Thermophysics,2014,35(11):2220- 2224.
[6] XIONG Qingang,YANG Yang,XU Fei.Overview of computational fluid dynamics simulation of reactor-scale biomass pyrolysis[J].ACS Sustainable Chemistry&Engineering,2017,5(4):2783-2798.
[7] 张玉,翟明,张波,等.生物质旋风热解炉气相等温流场数值模拟[J].节能技术,2015,33(5):413-419.ZHANG Yu,ZHAI Ming,ZHANG Bo,et al.Numerical simulation for the gas-phase isothermal flow field of a biomass cyclone pyrolysis burner[J].Energy Conservation Technology,2015,33(5):413-419.
[8] 王霄,司慧,程琦.环形流化床生物质热裂解反应器的传热分析[J].科技导报,2013,31(14):30-35.WANG Xiao,SI Hui,CHENG Qi.Heat transfer analysis of annular fluidized bed biomass pyrolysis reactor[J].Science & Technology Review,2013,31(14):30-35.
[9] BLANCO A,CHEJNE F.Modeling and simulation of biomass fast pyrolysis in a fluidized bed reactor[J].Journal of Analytical and Applied Pyrolysis,2016,118:105-114.
[10] RANGANATHAN P,GU S.Computational fluid dynamics modelling of biomass fast pyrolysis in fluidised bed reactors,focusing different kinetic schemesing different kinetic schemes[J].Bioresource Technology,2016,213:333-341.
[11] LEE E J,PARK C H,CHOI S H.Numerical study on fast pyrolysis of lignocellulosic biomass with varying column size of bubbling fluidized bed[J].ACS Sustainable Chemistry & Engineering,2017,5(3):2196-2204.
[12] SHARMA A,PAREEK V,ZHANG D K.Biomass pyrolysis—a review of modelling,process parameters and catalytic studies[J].Renewable and Sustainable Energy Review,2015,50:1081-1096.
[13] MILLER R S,BELLAN J.A generalized biomass pyrolysis model based on superimposed cellulose,hemicellulose,and lignin kinetics[J].Combustion Science and Technology,1997,126(1/6):97-137.
[14] XUE Q,DALLUGE D,HEINDEL T J,et al.Experimental validation and CFD modeling study of biomass fast pyrolysis in fluidized-bed reactors[J].Fuel,2012,97:757-769.
[15] BOATENG A A,MTUI P L.CFD modeling of space-time evolution of fast pyrolysis products in a bench-scale fluidized-bed reactor[J].Applied Thermal Engineering,2012,33-34:190-198.
[16] XIONG Q G,KONG S C,PASSALACQUA A.Development of a generalized numerical framework for simulating biomass fast pyrolysis in fluidized-bed reactors[J].Chemical Engineering Science,2013,99:305-313.