二级环流反应器中收缩-膨胀隔板的性能优化

Optimization of contraction-expansion partition in a two-stage internal airlift loop reactor

通过在二级环流反应器两级之间安装具有收缩-膨胀形状的隔板,可以有效减小两级之间的液相回流流量,但同时会增加流体流动阻力。为了在减小液相回流流量的前提下减小流动阻力,本研究对隔板进行优化设计。首先通过模拟计算获得不同隔板下的压降和液相回流流量,随后对数据进行拟合,得到压降、液相回流流量与结构参数的关联式。计算结果表明当表观气速较小时,隔板宽度对压降影响较大,高度的影响较小。表观气速增大时,隔板高度对压降的影响变大。在所有气速下,隔板宽度是影响液相回流流量的决定因素。最后通过多目标优化,获得了在不同表观气速下最优隔板的Pareto前沿。

Loop reactors are widely applied in industries because of good characteristics of gas-liquid in-teraction,and a series of internals are developed and equipped with the reactor to further reinforce the in-teraction.The installation of a contraction-expansion partition between two stages in a two-stage airlift loop reactor can effectively reduce the reversed liquid flow between the stages,while it increases the flow resistance.To pinpoint the effect of width and height of the partition on flow dynamics and obtain the par-tition which can reduce the flow resistance while decrease the reversed liquid flow,this study conducts an optimization of the partition utilizing CFD-PBM and multi-objective optimization methods.Firstly,a se-ries of numerical simulation-based experiments with various partitions at three different superficial gas ve-locities are conducted to obtain the pressure drop and the reversed liquid flow in the two-stage loop reac-tor.It is found that the width and height of the partition as well as superficial gas velocities lead to differ-ent performance of flow dynamics.The width has a greater effect on pressure drop than the height at a low superficial gas velocity,while the effect of height on the pressure drop becomes larger as the superficial gas velocity increases and width is the determinant factor for the reversed liquid flow at all superficial gas velocities in the study.The correlations for pressure drop and the reversed liquid flow with the width and height of the partition are obtained by data fitting.The Pareto fronts for the structure of partition at vari-ous superficial gas velocities are obtained using multi-objective optimization with the pressure drop and the reversed liquid flow as the optimization objectives and the width and height of the partition as optimi-zation parameters.