旋风除尘器内生物质飞灰颗粒浓度分布特性研究
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摘要
鉴于生物质气化站旋风除尘器内飞灰颗粒的浓度较高且难以测量,其分离效率与高温强旋湍流场密切相关,为获得其内部飞灰颗粒的浓度分布特性,研究分离效率与生物质燃气温度及其速度的关系,借助计算流体力学(CFD)软件,并结合气化站旋风除尘器的特点建立仿真模型;然后以气化炉产出的高温燃气为研究对象,应用气体-颗粒耦合模型对风流-飞灰的耦合运移情形进行数值研究。结果表明:旋风除尘器环形空间内出现"顶灰环"现象;筒体空间对飞灰的分离能力明显优于环形空间;锥体和筒体内颗粒浓度分布曲线为两边高、中间低的浴盆曲线;燃气温度升高,飞灰在同一径向位置的浓度升高;旋风除尘器分离效率有随燃气进口速度的增加而先增高后降低的趋势。
In view of that the concentrations of fly ash particles in cyclone separators of biomass gasification station are very high,it is much difficult to measure the biomass ash concentration,and a cyclone separator's separation efficiency is closely related to the turbulent flow field with high temperature,a simulation model was established by computational fluid dynamics( CFD) software based on characters of cyclone separator in gasification station,for obtaining the concentration distribution of ash particles and studying the relationship between the separation efficiency,biomass gas temperature and gas velocity. The biomass gas at high temperature released from gasifier was taken as the object of this study. The coupling migration of both air and fly ash inside the cyclone separator at high temperature was studied in numerical simulation,using a gas-particle coupling mathematic model. The results show that the phenomenon of upper dust ring exists in the annular space,that the separation ability of cylinder space is much better than that of cone space,that the ash concentration distribution curve in cone space and that in cylinder space are a bathtub curve,that the ash concentration in the same radial position increases as temperature elevated,and that as the inlet velocity increases, the separation efficiency firstly increases, then decreases.
In view of that the concentrations of fly ash particles in cyclone separators of biomass gasification station are very high,it is much difficult to measure the biomass ash concentration,and a cyclone separator's separation efficiency is closely related to the turbulent flow field with high temperature,a simulation model was established by computational fluid dynamics( CFD) software based on characters of cyclone separator in gasification station,for obtaining the concentration distribution of ash particles and studying the relationship between the separation efficiency,biomass gas temperature and gas velocity. The biomass gas at high temperature released from gasifier was taken as the object of this study. The coupling migration of both air and fly ash inside the cyclone separator at high temperature was studied in numerical simulation,using a gas-particle coupling mathematic model. The results show that the phenomenon of upper dust ring exists in the annular space,that the separation ability of cylinder space is much better than that of cone space,that the ash concentration distribution curve in cone space and that in cylinder space are a bathtub curve,that the ash concentration in the same radial position increases as temperature elevated,and that as the inlet velocity increases, the separation efficiency firstly increases, then decreases.
引文
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[2]张秀敏.基于风险分析的生物质气化及净化模拟研究[D].沈阳:东北大学,2017.ZHANG Xiumin.Simulation of biomass gasification and purification based on risk analysis[D].Shenyang:Northeastern University,2017.
[3]CRISTOBAL C,ANTONIA C.Modeling the gas and particle flow inside cyclone separators[J].Progress in Energy and Combustion Science,2007,33(2):1-43.
[4]OGAWA A.Mechanical separation process and flow patterns of cyclone dust collectors[J].Applied Mechanics Reviews,1997,50(3):97-129.
[5]BOHNET M.Influence of the temperature on the separation efficiency of aerocyclones[J].Chemical Engineering and Processing,1995,34:151-156.
[6]SHIN Misoo,KIM Heysuk,JANG Dongsoon,et al.A numerical and experimental study on a high efficiency cyclone dust separator for high temperature and pressurized environments[J].Applied Thermal Engineering,2006,25(12):1 821-1 835.
[7]陈曦,葛少成,葛斐,等.针对矿山细粉尘的新型微雾旋风除尘系统[J].中国安全科学学报,2014,24(9):122-127.CHEN Xi,GE Shaocheng,GE Fei,et al.Study on novel micro-fog&cyclonic system for removing fine particulate[J].China Safety Science Journal,2014,24(9):122-127.
[8]薛晓虎,孙国刚,时铭显.旋风分离器内颗粒浓度分布特性的数值分析[J].机械工程学报,2007,43(12):26-33.XUE Xiaohu,SUN Guogang,SHI Mingxian.Numerical simulation of particle concentration distribution in cyclone separator[J].Chinese Journal of Mechanical Engineering,2007,43(12):26-33.
[9]O'ROURKE P J,SNIDER D M.Inclusion of collisional return-to-isotropy in the MP-PIC method[J].Chemical Engineering Science,2012,80(10):39-54.
[10]SNIDER D M,CLARK S M,O'ROURKE P J.Eulerian-Lagrangian method for three-dimensional thermal reacting flow with application to coal gasifiers[J].Chemical Engineering Science,2011,66(6):1 285-1 295.
[11]孙立,张晓东.生物质热解气化原理与技术[M].北京:化学工业出版社,2013:187-188.
[12]李美莲.生物质热解系统中旋风分离器分离性能的实验研究[D].淄博:山东理工大学,2012.LI Meilian.Experimental study on the performance characteristics of cyclone in biomass pyrolysis system[D].Zibo:Shandong University of Technology,2012.