CFD-DEM模拟气固两相在陶瓷膜内的流动特性
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摘要
针对多孔陶瓷膜内复杂的气固两相流动体系,首先用颗粒随机堆积方法对多孔陶瓷几何结构进行了构建.随后采用计算流体力学(CFD)描述气相的流动传递行为;采用离散单元法(DEM)描述颗粒相运动轨迹.模拟结果揭示了滤饼层在膜表面的形成过程,以及压降和粉尘去除率随滤饼层和过滤速度的演变情况.此外,还考察了系统压降随粉尘颗粒恢复系数的变化情况,当恢复系数为0.3时,系统压降存在一个相对较高值.该方法可以为除尘过程中粉尘颗粒在微孔尺度中的传递过程提供精确描述.
The geometric structure of ceramic membrane was constructed by the random stacking method of particle. Then transport characteristic of gas-solid phases in ceramic filters was investigated, among that the transport behavior of gas phase and solid phase were described by the computational fluid dynamics(CFD) and discrete element method(DEM), respectively. The simulation results revealed that the formation of cake layer on the membrane surface and the evolution of pressure drop and rejection with cake layer were observed. In addition, influence of various inlet velocities on pressure drop of the system was investigated. When recovery coefficient was 0.3, system pressure drop presented a relatively high value. It can be concluded that this method could provide an accurate description of transmission process of dust particles in microporous scale during the process of dust removal.
The geometric structure of ceramic membrane was constructed by the random stacking method of particle. Then transport characteristic of gas-solid phases in ceramic filters was investigated, among that the transport behavior of gas phase and solid phase were described by the computational fluid dynamics(CFD) and discrete element method(DEM), respectively. The simulation results revealed that the formation of cake layer on the membrane surface and the evolution of pressure drop and rejection with cake layer were observed. In addition, influence of various inlet velocities on pressure drop of the system was investigated. When recovery coefficient was 0.3, system pressure drop presented a relatively high value. It can be concluded that this method could provide an accurate description of transmission process of dust particles in microporous scale during the process of dust removal.
引文
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[2] Chen Y S,Hsiau S S.Influence of filtration superficial velocity on cake compression and cake formation[J].Chem Eng Proc,2009,48(5):988-996.
[3] Lupion M,Alonso-Farinas B,Rodriguez-Galan M,et al.Modelling pressure drop evolution on high temperature filters[J].Chem Eng Proc,2013,66:12-19.
[4] 王伟,李佑楚.颗粒流体两相流模型的进展[J].化工进展,2002,12(2):208-217.
[5] 李长志,王莹,董鹏.湍流气固两相流动数值模拟理论研究的最新进展[J].电力工程系统,2002,18(3):33-37.
[6] Tsuji Y,Tanaka T.Lagrangian numerical simulation of plug flow of cohesionless particles in a horizontal pipe[J].Power Technol,1992,71(3):239-250.
[7] Ouyang J,Yu A B.Simulation of gas-solid flow in vertical pipe by hard-sphere model[J].Particle Sci Technol,2005,23(1):47-61.
[8] 赵永志,程易,金涌.提升管与下行床颗粒团聚行为的离散颗粒模拟[J].化工学报,2007,58(1):44-53.
[9] Xie J,Zhong W Q,Jin B S,et al.Eulerian-lagrangian method for three-dimensional simulation of fluidized bed coal gasification[J].Adv Powder Technol,2013,24(1):382-392.
[10] Chu K W,Chen J,Yu A B.Applicability of a coarse-grained CFD-DEM model on dense medium cyclone[J].Minerals Eng,2016,90(1):43-54.
[11] Qian F P,Huang N J,Lu J L,et al.CFD-DEM simulation of the filtration performance for fibrous media based on the mimic structure[J].Computers Chem Eng,2014,71:478-488.
[12] 于先坤,钱付平,鲁进利.微细颗粒物在过滤介质中过滤特性的CFD-DEM模拟[J].土木建筑与环境工程,2014,34(A2):145-149.
[13] Johnson K L,Kendall K,Roberts A D.Surface energy and contact of elastic solids[J].Process Royal Soc London A,1971,324(1558):301-303.
[14] Justin L,Hsiao T C,Hsiau S S,et al.Effects of temperature,dust concentration,and filtration superficial velocity on the loading behavior and dust cakes of ceramic candle filters during hot gas filtration[J].Sep Purif Technol,2018,198(8):146-154.
[15] 徐南平,邢卫红,赵宜江.无机膜分离技术与应用[M]//北京:化学工业出版社,2003.
[16] 蔡桂英.高温陶瓷过滤器微细通道内气固两相流数值模拟[D].南京:东南大学,2003.