组合导向浮阀塔板的CFD模拟及反向流分析

精馏塔板上的气液两相流动对传质效率有重要影响。根据实验数据拟合得到平均气含率关联式,将其加入动量源项,采用Fluent软件对1.2 m直径的组合导向浮阀塔板上的气液两相流动进行CFD模拟,考察了塔板上的气液两相流动状况。清液层高度的模拟结果与实验数据关联式相吻合,验证了模拟的正确性。对塔板上液相的非理想流动进行了分析,通过对反向流进行量化和统计计算出反向流体积分数(即反向流体积占塔板总体积的百分比)。3块不同浮阀排布塔板的反向流体积分数时均值的计算结果表明,梯形浮阀和矩形浮阀的排布方式对反向流影响很大,通过合理排布能够使工业塔板的反向流体积分数时均值从22.0%下降到19.4%,降幅达到11.8%。本研究结果可望对塔板的设计和优化提供指导。

CFD simulation and backflow analysis of combined directed valve tray

The flow patterns and hydraulics of gas-liquid flow on a commercial scale distillation tray is of great importance in determining the tray efficiency. Based on experimental data, a new correlation of average gas hold-up was fitted and built in the inter-phase momentum transfer source for CFD simulations. The simulations of combined directed valve trays of 1.2 m air-water system were carried out by Fluent, a commercial CFD software, and the flow pattern characteristics was investigated. The clear liquid height determined from CFD simulations was in good agreement with the predicted results calculated from the correlation in this work, which proved the validity of simulations. Non-ideal flow of liquid phase on the trays was quantified by the backflow volume ratio T, the ratio of backflow volume to total grid volume. The time-averaged values of the backflow volume ratio (T_av) of 3 tray patterns with different arrangements of trapezoidal and rectangular directed valves were calculated respectively. The results showed that the different arrangements of two kinds of valves had remarkable influence on volume fraction of backflow. By reasonable arrangement, T_av could reduce from 22.0% to 19.4% with the decreased backflow volume by 11.8% compared to the industrial tray. This study was expected to provide a guidance for the tray design and optimization.