双进气道旋风分离器内不同粒径颗粒流动特性

摘要

采用改进的RNG k-ε湍流模型和欧拉多相流模型,对一种单入口双进气道旋风分离器内的气固多相紊流过程进行数值模拟.计算得到旋风分离器内不同粒径颗粒速度和浓度分布规律,结果表明:大粒径颗粒比小粒径颗粒轴向速度分布更平坦,切向速度峰值位置和外准自由涡区也越向壁面靠近;与普通单入口旋风分离器相比,相同处理量时,此种旋风分离器内速度和不同粒径颗粒浓度分布轴对称性更好,大粒径颗粒切向速度峰值位置外移更明显,筒体段颗粒有更向壁面浓集的趋势,锥体段不同轴向位置处中心旋流区双进气道的颗粒浓度低于单进气道的.小粒径颗粒捕集能力增强,有助于提高分离器分离效率,减少不稳定流动导致结焦的颗粒源供给,从流动角度保证了抗结焦和长周期稳定操作.%Having the improved RNG k-ε turbulence model and Eulerian multiphase mode employed to simu-late gas-solid multiphase turbulence flow in a cyclone separator with single inlet and double passage was imple-mented;and the regularities of velocity and concentration distribution of particles with different sizes were ob-tained through calculation.The results show that, the large-size particle's axial velocity distribution is more flat than that of the small ones,and the tangential velocity's peak position and free vortex region become clos-er to the wall.Compared with general cyclones with single inlet and the same process load,the axial symmetry of this double-passage cyclone's velocity and particle concentration is better.The peak position of large-size particle's tangential velocity moves outside more obviously.In cylinder section,the particles have the tenden-cy of concentrating toward the wall surface.In central vortex area of conical section, the double passage's particle concentration is lower than that with single passage.The enhancement of small-size particles' capture capacity can increase the separation efficiency and decrease the particle supply of the unstable flow coke gener-ation.This can reduce the coke generation and ensure long stable operation in view of the flow.