Numerical simulation of residence time distribution in multi-chamber fluidized bed with continuous feeding

To reveal the hydrodynamic characteristics and particle residence time distribution (RTD) patterns of a multi-chamber fluidized bed reactor, and to optimize its structure and operational parameters, a numerical model of a continuously fed bubbling fluidized bed was developed using the Eulerian-Eulerian two-fluid model with species transport equations. Comparative simulations were carried out for baffle-free fluidized beds and multi-chamber beds under varying baffle opening heights, outlet tube heights, immersed tube bundle configurations, and solid feed rates. The gas-solid flow patterns, RTD, and back-mixing behavior were systematically evaluated. The results show that the multi-chamber baffled bed effectively suppresses bubble growth and promotes uniform hydrodynamics across chambers. The baffle structure makes the RTD approach plug flow, increases the average particle residence time by 14.5%, and reduces the variance from 0.79 to 0.58, with an orifice height of 20 mm being optimal. Reducing bed height shortened residence time by 45.2% but had limited mixing benefits, while adding immersed tubes further reduced variance by 15.1%. Decreasing the solid feed rate from 80 g/s to 60 g/s increased average residence time but intensified back-mixing. This study offers theoretical and practical insights for the design and scale-up of high-performance calcium looping reactors for thermochemical energy storage.