内循环流化床颗粒流动特性的数值模拟

采用离散单元法分析了非均匀布风方式下流化床内的气固流动特性.数值模拟结果表明:床内存在大尺度的颗粒横向循环流动;高风速区为气泡活跃区域,气泡尾涡裹挟颗粒上升是形成内循环的关键环节;供风非均匀程度越大,颗粒内循环力度越强烈;改变风速,颗粒流量变化显著;倾斜布风板设计有利于促进颗粒定向循环过程.

Numerical Simulation of the Characteristics of Particle Flows in an Internally Circulating Fluidized Bed

Internally circulating fluidized beds play an important role in fields of energy and chemical industry.The hydrodynamics of the gas-solid flow in a fluidized bed with uneven gas supply was studied by(using) discrete element method(DEM).The results indicate that there are large scale particle circulations in the lateral direction.The analysis shows that the zone with faster gas feed is a bubble active zone,where there is an upward particles stream resulted from the transport of the bubbles,which is thought to be an important factor causing the circulating particle stream in the fluidized column.Moreover,the more uneven the gas is supplied,the more intensive the particle circulation is.And the particle flux is sensitive to the change of the gas velocity.The design of an inclined distributor helps to enhance such directional circulation in the bed.