催化裂化两段式环流汽提器结构模拟及优化

Numerical simulation of structure optimization for FCC two-stage annular strippers

采用CFD(计算流体力学)模拟方法及催化裂化汽提流动传质模型,以两段环流式汽提器为模拟对象并选取催化剂颗粒在环流汽提器中内、外环表观气速分别为0.175,0.043 m/s的工况下,对汽提器内的气固流动和汽提过程进行了模拟分析,得到了环流汽提器内气体和催化剂详细流动状况。在此基础上,采用模拟方法进一步对两段环流汽提器的高径比、环流挡板间距和内外径比等关键结构参数进行优化研究,通过分析不同结构参数对环流汽提器操作状况的影响规律及汽提效率,得到最优结构参数,即汽提器高径比为2.78,环流挡板间距为0.125 m,内外径比为0.667。与原汽提器结构参数进行对比,优化后汽提器的汽提效率可达到97.17%,比原汽提效率提高了1百分点。

The gas-solid flow and stripping process in a two-stage annular stripper of Fluid Catalytic Cracking （FCC） unit was simulated under the conditions of internal and external aparent gas velocities of 0. 175 m/s and 0. 043 m/s respectively by Computational Fluid Dynamics （CFD） approach, and the detailed flow patterns of gas and catalysts were obtained. The impact of key structure parameters of two-stage annular stripper （ the ratio of height to external radius, the baffle spacing, and the ratio of internal radius to external radius） on the gas-solid hydrodynamics and stripping efficiency of the annular stripper was further investigated. The performances of annular strippers with different structures were compared, and the optium structure parameters were obtained as follows ： the ratio of height to external radius is 2.78, the baffle spacing is 0. 125 m, and the ratio of internal radius to external radius is 0. 667. As compared with the original structure parameters, the stripping efficiency of the optimized annular stripper could reach 97.17%, which is about 1% higher than that of the original structure stripper.