高通量循环流化床2种返料系统气固流动特性数值模拟

Numerical Simulation of Gas-Solid Flow Characteristics of Two Kinds of Recirculation System in High-flux Circulating Fluidized Bed

采用计算颗粒流体力学(CPFD)方法在直径0.5 m、高8.5 m的高通量循环流化床物理模型上,对分别采用U型和N型返料阀的全回路进行气固流动特性数值模拟研究。对比分析了不同工况下提升管颗粒浓度、物料循环流率和压差梯度分布等,并以此评价返料器的工作性能。循环物料为B类颗粒,初始床料量M p为380~665 kg。在提升管底部以均匀进气的方式通入流速为1.5~5.5 m/s的空气。结果表明:在采用相同流通面积的U型和N型返料阀的全回路流动中,后者的提升管颗粒浓度更高;在M p为600 kg时,N型阀最大返料流率为1220.85 kg/(m 2·s),而U型阀仅能达到904.37 kg/(m 2·s);N型阀设计更满足高通量循环要求,操作弹性大且物料循环稳定。

Computational particle fluid dynamics(CPFD)approach was employed to investigate the gas-solid flow behavior using a U-type and N-type return valve in a high-flux circulating fluidized bed physical model with a diameter of 0.5 m and a height of 8.5 m.The riser particle volume fraction,solid circulation flow rate and pressure gradient distribution of the two models under different working conditions were compared and analyzed.The circulating material is geldart B particles,and the initial bed particles mass M p is 380~665 kg.Air at a flow rate of 1.5 to 5.5 m/s is blown at the bottom of the riser.The results show that in the full-loop flow of U-type and N-type return valves with the same flow area,the riser particle volume fraction of the latter is higher;when the M p is 600 kg,the maximum return flow rate of the N-type valve is 1220.85 kg/(m 2·s),while the U-valve can only reach 904.37 kg/(m 2·s);the N-type valve meets the design requirements of high-flux circulation,and has high operational flexibility and stable material circulation.