聚丙烯环管反应器的流体力学模拟

Fluid dynamics simulation of polypropylene loop reactor

采用颗粒动力学为基础的Euler-Euler双流体模型研究反应器内液固相的流动力学特性.通过fluent软件,采用标准k-ε模型描述流体的湍流状态、Gidaspow曳力模型描述流体的相互作用力,运用SIMPLE算法求解速度场.结果表明：在5～9m/s的浆液速度范围内,环管反应器直管段的固相体积分数分布均匀,弯管段的固相体积分数分布不均匀;浆液速度增大,其固相体积分数分布的非均匀性增加;当固相体积分数为0.35时,浆液密度为563～571千克/立方米.通过对速度场的分析可知,上升管中段的流速为6～7.5 m/s,速度呈对称分布;下降管中段的流速为5～8 m/s,速度呈非对称分布.计算结果与工厂实际生产情况接近,表明欧拉双流体模型能有效地描述环管反应器内浆液流动形态.

The hydromechanics characteristics of liquid-solid phase in the loop reactor were studied using the Euler-Euler two-fluid model based on granules kinetics.Using the fluent software,we described the turbulent state of fluid by the standard k-ε mode,described the interaction between the fluids by Gidaspow drag force model and calculated the velocity field by the SIMPLE algorithm.The results show that the distribution of solid volume fraction is uniform in the straight pipe,but it is non-uniform in the curve-section pipe when the slurry velocity is in the range of 5 to 9 m/s; while the uniformity of solid volume fraction increases with the increase of slurry velocity; the slurry density is in the range of 563 to 571 kg/m3 when the solid phase volume fraction is 0.35.The results show that the slurry velocity in the middle position of ascending pipe is in the range of 6～7.5 m/s with symmetrical distribution; while the slurry velocity in the middle position of descending pipe is in the range of 5 to 8 m/s with an asymmetrical distribution.The calculation results are in agreement with industrial situation,which show that the Euler-Euler two-fluid model can effectively describe the slurry flow patterns in the loop reactor.