三维旋流喷动流化床气固两相流动特性模拟

Simulation of gas-solid flow characteristics in three-dimensional rotational spouted-fluidized bed

为了从理论基础上研究带风帽的旋流喷动流化床干燥器内气固两相流流动特性,采用欧拉多相流模型对一台旋流喷动流化床试验台进行三维数值模拟,分析了各种不同底部进风速度V底与切向进风速度V切比例对旋流喷动流化床干燥器内的气体速度分布和颗粒速度分布特性的影响,以及当V底/V切为30 m·s-1/30 m·s-1时,探讨了气固流动状态随时间的变化规律。研究结果表明:增大V切,有利于增加近壁面区域的气体流动速度和促进气固相的充分混合,增加气体和颗粒相的接触面积,有利于减少气相流动死区,降低黏性物料对筒体壁面的粘附程度。但由于切向风的卷吸作用所形成的负压会导致轴向气流减弱,不利于筒体中心区域气流的轴向发展,降低了轴向风对颗粒层的穿透效果。

In order to study the gas-solid flow characteristics of a rotational spouted-fluidized bed dryer with wind caps theoretically, the eulerian multi-phase model was applied in three-dimensional numerical simulation of a rotational spouted-fluidized bed test bench. The effect of different velocity ratios between bottom wind and tangential wind on gas velocity distribution and particle velocity distribution characteristics in the rotational spouted-fluidized bed dryer was analyzed, and the change law of gas-solid flow state at the velocity ratio of 30 m· s^-1/30 m· s^-1 was studied. The results show that the increase of tangential wind velocity is propitious to increase the gas flow rate in the region near the wall and make the gas-solid phase mix completely; increasing the contact area of gas and particle phase may reduce the gas flow dead zones and reduce the adhesion of viscous materials to cylinder wall. However, the negative pressure formed by the entrainment effect of tangential wind goes against the development of gas flow in the central region, reduces the penetration effect of axial wind to the granular layer.