移动颗粒床中高温气体渗流传热数值计算

GAS FLOW AND HEAT TRANSFER IN MOVING PARTICULATE BED

针对移动颗粒床中物料层内的高温气体渗流传热现象 ,考虑渗流与传热的相互作用 ,采用局部非热平衡假设建立了多孔介质渗流传热物理数学模型并进行了数值计算 .研究了不同情况下床内填充多孔介质中的流速、气固温度和床层压力损失 .计算结果表明 ,高温热气对移动床颗粒料层的热渗透主要发生在渗流入口端区域 ,增大入口渗流速度以及减小床层物料下移速度将导致物料温度沿床高慢速下降 ,热渗透深度扩大 ,热渗透作用区域内的物料温度水平提高 .在热渗透作用区域 ,孔隙率对流场和压力损失有很大的影响 .

High heat penetration into a moving particulate bed is described mathematically with a comprehensive heat and mass transfer model. The distribution of gas velocity and pressure, the temperature field of gas and solid in the moving particulate bed are examined at different conditions. The results show that thermal penetration into the moving packed-bed particles by fluid flow in porous media is high only in the position near the gas entrance. The thermal penetration thickness tends to increase with the fluid flow velocity and decrease with the particle moving velocity. In the region of thermal penetration, the porosity of solid bed has significant effect on gas field and pressure loss. It is feasible to reduce the gas pressure loss by a larger width/height packed bed in design and operation. The correspondence between thermal infection depth and particle bed height would be helpful to keep high capacity of reactor and reduce the cost of operation.