Effect of steam injection location on syngas obtained from an air-steam gasifier

For a fluidized-bed gasifier, reaction conditions vary along the height of the reactor. Hence, the steam injection location may have a considerable effect on the syngas quality. The objective of this study was to investigate the effects of steam injection location and steam-to-biomass ratio (SBR) on the syngas quality generated from an air-steam gasification of switchgrass in a 2-5 kg/h autothermal fluidized-bed gasifier. Steam injection locations of 51, 152, and 254 mm above the distributor plate and SBRs of 0.1, 0.2, and 0.3 were selected. Results showed that the syngas H2 and CO yields were significantly influenced by the steam injection location (p < 0.01) and SBR (p < 0.05). The steam injection location also significantly influenced hot and cold gas, as well as carbon conversion efficiencies. The best syngas yields (0.018 kg H2/kg biomass and 0.513 kg CO/kg biomass) and gasifier efficiencies (cold gas efficiency of 67%, hot gas efficiency of 72%, and carbon conversion efficiency of 96%) were at the steam injection location of 254 mm and SBR of 0.2.