Numerical analysis of hydrodynamics and thermochemical property of biomass gasification in a pilot-scale circulating fluidized bed

Abstract

This study presents a three-dimensional reactive multiphase particle-in-cell (MP-PIC) model to simulate the hydrodynamics and thermochemical property of the biomass gasification process in a pilot-scale circulating fluidized bed gasifier. The bed hydrodynamics and thermochemical characteristics are investigated, together with discussing the effects of operating conditions on the species distribution, lower heating value (LHV), and combustible gas concentration (CGC). The results show that solid particles present oscillation behaviors for the time elapsed at the turbulent fluidization regime. Solid flux and rising velocity have peaks of about 249 kg/(m2·s) and 6.2 m/s in the core region of the bed, respectively. Increasing the gasification temperature reduces the CGC from 15.85% to 15.16%. However, only the concentration of H2 increases with the enlargement of the steam biomass ratio. Comparatively, the equivalence ratio (ER) has the most direct impact on gasification efficiency, and the increase of the ER adversely affects the LHV and CGC. The effect of particle diameter on the LHV, the magnitude of which can cover a range from 3.87% to 3.98%, is negligible compared with the other operational parameters, at least for the specific cases in the present investigation.