气固流化床中颗粒分离的软球模拟

Segregation of Particles by Soft-sphere Simulation in Gas-solid Fluidized Beds

基于颗粒轨道模型,建立了粒径服从均匀分布的二组分颗粒分离的软球模型.其中流体运动用Navier-Stokes方程描述,颗粒运动满足牛顿第二定理,两相间的耦合由牛顿第三定理确定.研究了表观气速、颗粒平均质量、颗粒直径分布范围、颗粒碰撞参数对二组分颗粒分离的影响.研究结果表明:表观气速太大或太小都会减弱二组分颗粒的分离行为;在各组分颗粒密度不同条件下,不同组分颗粒的平均质量相差越大,颗粒分离越明显;在各组分颗粒密度相同条件下,不同组分颗粒的直径分布范围差别越大,颗粒分离越好;理想状态下,颗粒分离的速度较快,且分离较完全.

Based on the particle-motion-resolved discrete model, a soft-sphere model used for the simulation of segregation behavior of particles in gas-solid fluidization is established in which particle diameters obeys the even distribution. The particles motion satisfies the Newton＇s second law and fluid motion is described by Navier-Stokes equation. The interaction between two phases is treated with the Newton＇ s third law. The influences of gas superficial velocity, particles average mass, the scope of particle diameters distribution, and the collision parameters on the segregation of particles are discussed. As a result, if the gas superficial velocity is too big or too small, the particle segregation will be weakened. When the densities of two solid phases are different, the more different the particle average mass, the more distinct the particle segregation. When the densities of two solid phases are the same, the more different the scope of particle diameters distribution, the better the particle segregation. In the ideal condition, the velocity of particles segregation is more quickly, and the particles segregation is more pronounced.