高温鼓泡床内气固两相流动的数值模拟

Numerical Simulation of Gas-Solid Flow in Bubbling Bed at High Temperature

针对高温鼓泡床内的气固两相流动,在热态鼓泡床中试装置的基础上建立了鼓泡床物理模型,采用团聚曳力模型对高温鼓泡床内气固两相流动进行模拟研究。模拟结果表明,当颗粒当量直径为235μm时,模拟得到的床层密度与实验值吻合较好;随温度的升高,气固曳力增大,使得床层密度有所降低;对颗粒体积分数的概率分布及压力脉动方差的分析表明,随温度的升高,固相中的颗粒减少,而气相中的颗粒增多,同时气泡尺寸有所增大,床层气固两相运动更加剧烈。

Gas-solid flow behavior in a bubbling bed at high temperature was simulated by means of the computational fluid dynamics. The effect of the different equivalent diameters of the solids on the flow was investigated to modify the proposed drag model. The simulated bed densities were in good agreement with the experimental data at the equivalent diameter 235 μm. With rise of temperature, the drag force between gas and solid phases strengthened, which led to reduction of the bed density. Analysis of the probability density distribution of the solid volume fraction showed that few particles were in the dense phase and many particles were entrained into the dilute phase at high temperature. The pressure fluctuation intensified with rise of the temperature, which indicated formation of the bigger bubbles and more volatile gas-solid flow.