对大型液-固两相搅拌槽事故停车及再启动过程的数值模拟研究

Numerical Simulation on the Processes of Accidental Power Cut and the Restart of a Large-Scale Solid-Liquid Two-Phase Stirred Tank

建立了一个工业氢氧化铝结晶搅拌槽的计算流体力学CFD模型,应用欧拉-欧拉多相流模型模拟了槽内颗粒的悬浮过程。针对实际生产中需考虑的停车事故设计,应用瞬态解算器和滑移网格法,在得到的稳态模拟结果基础上,模拟计算了停车0.5 h以及再启动过程中流场的发展变化过程,分析了流体速度分布、颗粒相分布以及搅拌功率变化过程。计算分析结果表明,事故停车之后槽内流体循环会逐渐消散,颗粒会逐渐在底部沉积。停车0.5 h后再启动约10 s搅拌功率会达到远高于搅拌电机额定功率的峰值,如不设计辅助搅拌装置则会导致电机损坏。文中提出的模型可以作为搅拌槽优化设计的有效仿真工具。

A CFD（Computation Fluid Dynamics） model of commercial aluminum hydroxide stirred tank was established, and the Euler-Euler multi-phase model was used to simulate the mixing and suspension of the aluminum hydroxide particles in the stirred tank. In order to study the potential accidental power off scenario which is ought to be considered in the commercial design, the simulation technologies including moving mesh and transient solver were adopted, and on the base of steady simulation results, the flow field developments in the processes of stirring abnormal stop and restarting were simulated separately. The calculation results of both the fluid velocity and the particle phase distributions and the stir power variation were analyzed, the results show that the solid particles will sink down and pile up on the bottom of the stirred tank, which makes that, after the accident power cut down more than 0.5 hour, the start up stir power of the restarting process becomes much higher than the rated stir power, and if without the help Of the assisting equipment, the electrical appliance of the stirrer will break down when restarting. Finally, the model presented in this paper is an available tool for the optimal design of the large-scale stirred tanks.