壁面约束对提升管内细长颗粒浓度分布的影响

基于欧拉一拉格朗日方法,并根据刚体动力学理论及经典流体力学理论,建立了细长颗粒流化运动三维模型.模型中考虑了细长颗粒与壁面三维碰撞问题.基于此模型,并根据实际的结构及运行参数,对细长颗粒在流化床的浓度分布特性进行了数值实验.研究表明,如果不加入惰性物料,细长颗粒无法自身在提升管内形成明显的悬浮段和密相区,也不会在密相区形成明显的双向流动;细长颗粒在流化运动过程中伴有一定的迁移现象,颗粒由四周慢慢向中心移动;壁面附近区域的细长颗粒的浓度分布受流化风速影响明显,这也可能与壁面约束效应有关.

Effects of wall on concentration of slender particles in the riser

A three-dimensional fluidization model of slender particles is established with the Euler-Lagrange method,rigid dynamics and fluid mechanics models. The effects of particle-wall collision model are included in this model.Based on the established model,the concentration features of slender particle are studied using actual parameters of structure and operating.It is found that the slender particles cannot form evident dense-phase zone and dilute-phase zone without the inert materials in the riser,and two-way fluidizing of slender particles cannot form in the dense-phase either.The slender particles move slowly from nearby region of wallto centre zone with the increment of position of height;that is to say,there is the phenomenon of migration during the process of fluidization.The concentration of slender particles of nearby region of wall is affected by fluidizing velocity and the wall.