Characterization of a dual fluidized bed gasifier with blended biomass/coal as feedstock

Abstract

A one-dimensional model is built based on the commercial Aspen Plus software to kinetically simulate the biomass/coal co-gasification process in a dual fluidized bed gasifier. The synergistic effect on the co-gasification kinetics is allowed for, and is coupled with the gas-solid flow hydrodynamics. With the developed model, the effects of different key operating parameters including the biomass blending ratio (R_b), the initial bed temperature (T_g), the feedstock mass flow rate (F_fs), the bed material flux (F_bm) and the steam to carbon ratio (R_sc) on the resultant syngas composition and the supplemental fuel mass flow rate (F_sf) are investigated, and the operation parameters are optimized. It is found that increasing R_b and T_g can enhance the gasification, while increasing F_fs and R_sc restricts the gasification. Increasing F_bm has slight effect on the gasification results but can reduce F_sf. The cold gas efficiency is up to 78.9% under the proposed optimum condition.

Keywords: Alkali metals; Aspen Plus; Co-gasification; Dual fluidized bed gasifier; Synergistic effect.