Experimental study on combustion of torrefied palm kernel shell (PKS) in oxy-fuel environment

Oxy-combustion of biomass can be a major candidate to achieve negative emission of CO2 from a pulverized fuel (pf)-firing power generation plants. Understanding combustion behavior of biomass fuels in oxy-firing conditions is a key for design of oxy-combustion retrofit of pulverized fuel power plant. This study aims to investigate a lab-scale combustion behavior of torrefied palm kernel shell (PKS) in oxy-combustion environments in comparison with the reference bituminous coal. A 20 kW(th)-scale, down-firing furnace was used to conduct the experiments using both air (conventional) and O-2/CO2 (30 vol% for O-2) as an oxidant. A bituminous coal (Sebuku coal) was also combusted in both air- and oxy-firing condition with the same conditions of oxidizers and thermal heat inputs. Distributions of gas temperature, unburned carbon, and NOx concentration were measured through sampling of gases and particles along axial directions. Moreover, the concentrations of SOx and HCl were measured at the exit of the furnace. Experimental results showed that burnout rate was enhanced during oxy-fuel combustion. The unburnt carbon in the flue gas was reduced considerably (75%) during combustion of torrefied PKS in oxy-fuel environment as compared with air-firing condition. In addition, NO emission was reduced by 16.5% during combustion of PKS in oxy-fuel environment as compared with air-firing condition.