煤液化热高压分离器煤粉漂移特性数值模拟与优化

Numerical simulation and optimization on pulverized coal drifting characteristics in high temperature and high pressure separator

为揭示煤液化热高压分离器(简称"热高分")内的煤粉漂移规律,基于热高分的结构特性和多相流物性参数,建立物理模型,并采用VOF(volume of fluid)模型和DPM(discrete phase model)模型,数值分析进口液固两相中固相质量分数、颗粒粒径对煤粉漂移特性的影响。研究发现:在气液交界面处,煤粉颗粒平均质量浓度最大,并随进口固相质量分数的增加而增大;小颗粒对气流的跟随性好,故气相出口的煤粉漂移率与颗粒粒径呈负相关关系;当进口固相质量分数增大到7%以上时,对应同一颗粒粒径下煤粉漂移率基本不变。通过在热高分上部增加45°倾斜挡板,发现气相出口处煤粉漂移率从2.03%下降到0.88%。

To discover the pulverized coal drifting law in the high temperature and high pressure（ HTHP） separator of coal liquefaction unit,the physical model was established on the basis of separator＇s structure and physical characteristics of multiphase flow,the volume of fluid（ VOF） model and the discrete phase model（ DPM） were used in this numerical simulation to analyze the influence of solid phase mass concentration and particle diameter on the pulverized coal drifting characteristics in HTHP separator. The results show that the mean particle concentration is the largest at gas-liquid interface,and it increases with solid phase mass concentration. There is a negative correlation between pulverized coal drifting ratio in gas outlet and particle size because small particles follow airflow well,and the pulverized coal drifting ratio basically remains unchanged in the same particle diameter when solid phase mass concentration increases to more than 7%. The pulverized coal drifting ratio can be reduced from 2. 03% to 0. 88% by using a 45° inclined baffle in the upper part of HTHP separator.