Abstract
Various biobriquettes made by mixing three Chinese bituminous coals and three types of biomass like agricultural and forest wastes were heat-treated at 1173K in nitrogen. Each biobriquette char obtained was then gasified with steam at 1073-1273K and 0.012-0.069MPa as the partial pressure to measure the reactivity. Results under identical gasification conditions showed the followings: (1) Biobriquette chars had larger reaction rates than the corresponding coal chars used for comparison. When Ca(OH)_2 as desulfurization agent was added, the reactivities of biobriquette chars were further enhanced to the same level of that for brown coal. (2) Increase of the rate in the presence of biomass and by addition of Ca(OH)_2 can be explained by such a situation that the portion of biomass would be preferentially gasified, thereby the contact area between unreacted coal char and steam could be increased and by combined catalytic effect of inherent biomass ash and calcium component, respectively. (3) For the composition of gases evolved, it depended on the ratio of coal/biomass in weight, gasification temperature, and the partial pressure of steam, indicating the controllability of H_2/CO ratio by selecting these operating factors.
