Eulerian-Lagrangian simulation of chemical looping combustion with wide particle size distributions

Abstract

Chemical looping combustion (CLC) is a promising technology efficiently utilizing fossil fuels to reduce CO2 emissions. This work numerically studies the CLC process in a three-dimensional dual circulating fluidized bed (DCFB) using a reactive multi-phase particle-in-cell (MP-PIC) method based on the Eulerian-Lagrangian framework with the discussion of the effects of particle size distribution (PSD) width on bed hydrodynamics and system performance. The PSD is described by a log-normal function. A wider PSD width is produced by adjusting the variation of standard deviation. The results show that the PSD width exerts a significant influence on the physical and thermochemical characteristics, including particle residence time, solid holdup, gas component concentration distribution, chemical reaction rates, oxygen transport efficiency, and fuel conversion rates. A larger PSD width gives rise to a shorter particle residence time in the reactor and enhances the particle exchange and oxygen transport efficiency between the air reactor and fuel reactor. Moreover, the CO2 yield and the fuel conversion rates are promoted under a larger PSD width.