Kinetics of gasification of coal, biomass and their blends in air (N 2/O 2) and different oxy-fuel (O 2/CO 2) atmospheres

Abstract

Kinetics of bituminous coal and palm shells were evaluated using thermo-gravimetric analysis under different environments (N 2/CO 2/O 2). The observed percent mass loss of biomass was higher than mass loss percentage of coal because biomass had higher reactivity and volatile matter content. Ignition temperatures of pure coal, biomass and their blends were also investigated and it was observed that biomass blends had improved ignition properties in both air and oxy-fuel environments. However, the combustion mechanism wasn’t affected. Different mixtures of CO 2/O 2 were also used on 10% palm shell–90% coal samples and compared with air as the reference. At the same composition of oxygen in oxy-fuel as that of simulated air, ignition temperatures were slightly higher and mass loss percentages were marginally lower. However, this difference due to heat capacities of N 2 and CO 2 was meager and was considered negligible. Upon increasing O 2 content, lower ignition temperatures were observed. Kinetics of coal, palm shell and their blends were determined at different gas mixture compositions using Doyle’s and Coats-Redfern’s models. For both models, E was found to decrease with increasing palm shell composition in coal as well as increasing O 2 concentration in oxy-fuel. However, a reverse trend was observed for the pre-exponentional factor( A).