(517a) Modeling of Steam-Air-Blown Gasification for Biomass in a Dual Circulating Fluidized Bed (CFB) Gasifier

A three-steady-stage thermodynamic equilibrium model including mass and energy balances was applied for steam-air-blown biomass gasification in a dual fluidized bed (DFB) to calculate the product gas composition, the carbon conversion, the heat recovery of biomass, and the heat demand needed in bubbling fluidized bed (BFB) gasifier. A complete combustion of both unconverted char and additional fuel was assumed in the combustion reactor (riser). The heat required for gasification reaction was provided by the circulating bed material (silica sand).

The final composition of the producer gas is obtained from two-stage equilibrium model incorporated with biomass pyrolysis. For the composition of H₂ and CH₄ of the producer gas, the equilibrium model shows good agreement with experimental data collected from others literature. The effects of reaction temperature, steam to fuel ratio, and air to fuel ratio on the composition of producer gas and overall performance of a DFB gasifier are evaluated.