板式塔弓形降液管液相流场CFD数值模拟

CFD simulation of liquid flow field in downcomer of trayed tower

弓形降液管是板式塔的重要组成部分,对弓形降液管的液相流场分布研究有重要意义.采用计算流体力学软件Fluent及其前处理器Gambit,选用标准k-ε湍流模型及SIMPLEC算法,模拟了液体流过降液管底部的流场分布.结果表明：沿堰长方向,中间位置的速度比两侧位置的速度小18.9%~35.7%.沿降液管宽度方向,靠近塔壁处的液体速度沿从上往下的高度方向逐渐减小,而靠近堰壁处液体速度逐渐增大.降液管底部拐角处存在漩涡和缓流区.为检验模拟结果,实验在直径为1 200 mm有机玻璃塔内进行,空气-水为实验物系.采用热膜风速仪对弓形降液管底部的液体速度进行测量,得到其流场分布.将模拟结果与实验结果进行比较,两者吻合得较好.

Segmental downcomer is most commonly used in distillation columns,so it is very significant to study the hydrodynamic performance of the downcomer.Using computation fluid dynamics（CFD） simulation,the three-dimensional liquid velocity field in the downcomer was investigated by FLUENT.The SIMPLEC algorithm with staggering grid system was used in the solution procedure of the discretized equations based on the continuity and momentum equation and the standard k-ε model.The results showed that the velocity in the center of the plane parallel to the weir was smaller by 18.9%～35.7% than that on the both sides.In the plane vertical to the weir,the velocity near the tower wall decreased gradually from top to bottom,whereas,the velocity near the weir wall increased gradually.The vortex and stagnant pool existed at the downcomer bottom approach to the tower wall.The experiment was carried out with air-water system in a 1 200 mm column.The liquid velocity in the segmental downcomer was measured by constant temperature hot-film anemometer.By comparison of the simulation liquid velocity value and experimental value,the simulation value agreed well with the experimental value.