新型内构件填充床反应器数值模拟——Ⅰ.气相流场和停留时间分布

Numerical Simulation of a Packed Bed Reactor with Novel Internals——Ⅰ.Flow Field and Residence Time Distribution of Gas Phase

针对含新型内构件的复杂填充床内部结构,建立了包含颗粒填充床、气体通道、气体挡板的几何模型下气液两相流动的数学模型,采用计算流体力学(CFD)技术首先对气流在复杂结构下的流动分配、流型和停留时间分布进行了详细的模拟,并考察了操作参数和结构设计对流场和停留时间分布的影响.通过压降实验数据在宏观尺度上验证了CFD模拟的正确性.详细的内部流场展示了气体在颗粒床和气体通道内的曲折流动行为,增加了气体的平均停留时间;停留时间分布预测表明气相流动没有短路发生,平均停留时间与表观气速成反比.内构件结构参数对气体流场和停留时间分布产生重要的影响.

A mathematical model describing the gas flow in a packed bed with novel internals was established, which considered the combined geometry of a packed bed of particles and the gas passages with baffles. Computational fluid dynamics （CFD） simulation was carried out to study the flow pattern and the residence time distribution （RTD） of gas phase under different operating conditions and reactor geometries. The experimental data of the pressure drop validated the CFD simulation at the reactor scale. The detailed flow field inside the reactor was disclosed with the simulation, which showed the zigzag flow behavior of the gas phase through the packed bed and the gas passages. The gas did not by-pass the system because the reactor remained to be the configuration with multiple compartments connected in series. The design of the internal imposed strong influence on the gas flow field and the corresponding RTD, which allowed a large room for optimizing the packed bed with internals.