Numerical Analysis of Particle Residence Time Distribution Characteristics in Fluidized Bed Based on Orthogonal Test

[Objectives] The residence time distribution (RTD) of particles is an important index to evaluate gas-solid mixing degree in fluidized bed, but there are many influencing factors and it is difficult to control. In order to design and optimize the fluidized bed with continuous operation, it is necessary to explore the influence of structure and operation parameters on RTD of particles. [Methods] Based on the Eulerian-Eulerian two-fluid model coupled with the component transport equation, a three-dimensional numerical calculation model of the particle RTD in a rectangular fluidized bed with continuous operation is established. The orthogonal simulation tests with 25 sets are designed to investigate the effects of the baffle structure, number, flow width, particle inlet mass flow rate, and superficial gas velocity on the particle RTD. [Results] The inlet mass flow rate of particles has the most significant effect on the average residence time of particles, followed by the superficial gas velocity, and both of them are inversely proportional to the average residence time of particles. However, for the dimensionless variance of RTD, the number of baffles and the mass flow rate are important influencing factors. The increase of them will reduce the dimensionless variance, weaken the backmixing degree of the fluidized bed, and make the flow tend to plug flow, but the number of baffles has a greater impact. [Conclusions] The average residence time of particles can be effectively controlled by adjusting the mass flow rate of particles. The number of baffles is a key structural parameter for designing fluidized beds.The research results can provide theoretical guidance for the design and optimization of fluidized bed.