New annular steam-biomass reactor design for hydrogen-enriched producer gas production

Biomass conversion using air gasification suffers from the high N2 gas dilution. Using steam as gasifying agent eliminates this issue, but heat must be supplied efficiently using external sources. This study investigated biomass steam gasification in a new annular reactor design with a gas heating jacket. This experimental study used two steam injection configurations: bottom and top to evaluate the effect of gasification temperature and steam to biomass (S/B) ratio on H2% using wood pellets. Temperature varied in the range of 300-600 degrees C for bottom injector, while S/B varied from 1.7 to 2.6. Peak H2% was 27.7% and higher heating value (HHV) of gas was 7 MJ/Nm3. Using top injector enhanced the heat transfer which elevated the temperature range (700-950 degrees C) and reduced S/B ratio in the range of 1.3-2.2, achieving H2% of 44% at the optimum steam flow rate of 30 g/min with HHV of 12.7 MJ/Nm3. Tar contamination was reduced from 13.6 g/m3 to 7.4 g/m3 with the increase of S/B. The effect of different fuels including coconut shells charcoal (CSC), palm kernel shells (PKS), and Empty fruit bunch (EFB) on H2% was also investigated. H2% was 47.7% for CSC, followed by 46.3% for PKS and 44.7% for EFB.