粗旋风分离器内气相流场研究与数值模拟

采用CFX软件提供的DSM模型对催化裂化沉降器内粗旋风分离器中的气相流动规律进行了数值模拟,并与用五孔探针测试的流场进行了比较。结果表明,采用合适的网格系统和边界条件等,DSM模型对粗旋风分离器具有良好的预测精度。对实验和模拟结果的分析表明,粗旋风分离器内流场与常规旋风分离器的流场不同,升气管和料腿均存在回流区,升气管回流区最大可波及分离空间,对分离空间流场有很大干扰。料腿直径的减小以及灰斗的存在使升气管排出的气量增大并使升气管、料腿回流区大幅减小,从而在宏观上保证了气固分离效率和较小的气相停留时间。

NUMERICAL SIMULATION AND EXPERIMENTAL STUDY ON GAS FLOW FIELD IN A ROUGH-CUT CYCLONE SEPARATOR

Gas flow behavior in a rough-cut cyclone separator in FCC disengager was studied. DSM model provided by CFX5. 5 was adopted to predict the gas flow field, and simulation results were compared with the experimental data measured by means of five-hole probe. Applying proper net region and boundary condition, DSM model could precisely predict the rough-cut cyclone separator. Both of the experimental and simulation results showed that the flow field in rough-cut cyclone separator was different from conventional cyclone separator, the former existed reversed flow in the exit tube and dipleg, and the reversed flow in the exit tube could spread to the separation space, and strongly disturb the flow field. Reducing the diameter of the dipleg and the existence of a hopper could increase mass flux out of the exit tube as well as decrease the reversed flow distinctly, thus a comparatively high gas-solid separation efficiency and short residence were ensured.