Study on circulating characteristics of circulating fluidized bed

Abstract

Based on the Euler-Euler two-fluid model, the circulating fluidized bed was simulated using the computational fluid dynamics (CFD) method. The physical model of the circulating turbulent fluidized bed had an inner diameter of 76mm and a height of 2000mm. The circulating material consisted of class B particles, with an initial bed material mass (Mp) of 0.188kg. Air was uniformly introduced at a velocity of 0.3m/s at the bottom of the riser, and secondary air was introduced at a velocity of 0.9m/s at the secondary air inlet. Numerical simulations were conducted to study the gas-solid flow characteristics of the entire circuit. The turbulent bed, fast bed particle concentration, material circulation rate, and pressure drop gradient were analyzed to evaluate the performance of the entire circuit. The results showed that the particle concentration at the bottom of the riser was higher in the overall circuit flow, and a turbulent state could be achieved at low gas velocities. The particle concentration in the transport bed was low, indicating good gas-solid interaction. Strong backmixing occurred at the connection between the return valve and the turbulent bed. Additionally, there was intense gas-solid reaction at the secondary air inlet.