Gasification Characteristics of Coal/Biomass Blend in a Dual Circulating Fluidized Bed Reactor

Abstract

The effects of reaction temperature (750-900 degrees C), steam/fuel ratio (0.5-0.8), and biomass ratio (0, 0.25, 0.5, 0.75, 1) on the gasification characteristics have been determined in a dual circulating fluidized bed reactor (combustor, 0.04 m x 0.11 m x 4.5 m high; gasifier, 0.04 m x 0.285 m x 2.13 m high). Indonesian Tinto sub-bituminous coal and Quercus acutissima sawdust were used as the coal and biomass, respectively. The product gas yield, carbon conversion, and cold gas efficiency from gasification of biomass are higher than those of coal with increasing temperature and steam/fuel ratio. After pyrolysis, surface area, pore volume, and micropores of coal/biomass blend char increase. The maximum increase in gas yield can be obtained with a biomass ratio of 0.5 at the given reaction temperature. Calorific values of the product gas are 9.89-11.15 MJ/m(3) with the coal, 12.10-13.19 MJ/m(3) with the biomass, and 13.77-14.39 MJ/m(3) with the coal/biomass blends at 800 degrees C. The synergistic effects on the basis of calorific value and cold-gas efficiency are pronounced with the coal/biomass blends.