Experimental investigation of downdraft biomass gasifier fed by sugarcane bagasse and coconut shells

Biomass gasification is a process of converting solid biomass ingredients into combustible gas, which can be used in electricity generation. A biomass gasifier was designed with 30–40 kg/h downdraft, fabricated, and evaluated using sugarcane bagasse and coconut shells. The effect of equivalence ratio on syngas composition, heating value, syngas yield, gasification efficiency, and tar content was evaluated. Besides, the tar removal efficiency of different cleaning instruments was also evaluated. The investigation revealed that types of biomass feedstock and equivalence ratio have a significant effect on the performance parameter of the gasifier. The average syngas produced from 1 kg of sugarcane bagasse and coconut shells were 3.1 and 2.97 m3, while the average amount of tar produced from the same fuels was 2.5 and 2.2 g/Nm3. As ER increased from 0.17 to 0.22, the concentration of carbon monoxide (CO) and hydrogen (H2) was increased from 14 to 17.9% and 7.5 to 9.6%, respectively. However, the lower calorific value of syngas was increased from 4.4 to 5.4 MJ/Nm3. Removal efficiency of cleaning instruments is auxiliary filter (45.7%) < wet scrubber (54.2%) < biomass filter (56%) < cyclone separator (60.6%) when sugarcane bagasse was used as a biomass fuel, while for coconut shells, removal efficiencies of the cleaning units were auxiliary filter (52.9%) < cyclone separator (54%) < wet scrubber (59.4%) < biomass filter (65%) respectively.