Co-gasification of different biomass feedstock in a pilot-scale (24 kWe) downdraft gasifier: An experimental approach

Co-gasification is considered as a useful technique for post-treatment of anaerobic digestion residues. The present study has dealt with the efficiency parameter of 24 kWe downdraft biomass gasifier with 50% mixture ratio of wood chips + corn cobs and 50% ratio of sugarcane bagasse + coconut shells. The performance of the gasification process was assessed with respect to biomass ratios on gasification efficiencies, reactor thermal profiles and equivalence ratio on specific yield of syngas composition and tar contents. Trials were conducted at a temperature range of 650–950 °C using equivalence ratios from 0.15 to 0.30. The biomass feeding rate was maintained between 35 and 40 kg/h. The total volume of gas obtained from co-gasification of wood chips + corn cobs was low (75.6 m3) than the mixture of sugarcane bagasse + coconut shells (94.33 m3) of gas at 5% moisture content. The average yield of syngas produced from the mixture of 1 kg wood chips + corn cobs and sugarcane bagasse + coconut shells were 2.52 and 3.14 m3, respectively. These results have shown that the mixture of wood chips + corn cobs produced almost 4238.6 mg/m3 tar impurities compared with the co-gasification sugarcane bagasse + coconut shells that produced 3767 mg/m3 with LHV of 3.8 MJ/Nm3 and 4.56 MJ/Nm3 at 5% moisture content respectively. This research concluded that co-gasification of sugarcane bagasse + coconut shells were found to be a suitable feedstock mixture for gasification and utilization of syngas for power generation depends on tar production, the flowrate of syngas, and performance in a downdraft gasifier.