Simulation of CO2 capture process in gas-solid bubbling fluidized bed by computational mass transfer

Abstract

In this paper, a recently developed two-equation turbulent (TET) model based on the methodology of computational mass transfer (CMT) [1] is adopted to simulate the capture process of carbon dioxide by potassium carbonate particles in a gas-solid bubbling fluidized bed (BFB). The TET model uses two auxiliary equations, namely the concentration variance equation and its dissipation rate equation to determine the turbulent mass diffusion of species, which enables the simulation on mass transfer process be more rigorous than that based on empirical turbulent Schmidt number model. Comparison between the simulated results and experimental data in literature is made, which shows a satisfactory agreement (AARD% are 2.47 % and 8.45 % respectively for two cases of simulation) and thus verifies the validity of the model. Furthermore, the turbulent mass diffusion in the BFB is characterized and discussed. The calculated turbulent Schmidt number by the present model varies along axial and radial directions (with averaged value of 0.32), revealing that the use of constant turbulent Schmidt number (i.e., 0.7) is only an approximate.