Publication: Performance characteristics of air steam gasification in biomass downdraft gasifier– combustor
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Date
2023-10-01
Authors
Mohammad Junaid Khan
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Abstract
Nowadays, the world is promoting renewable energy through implementing the use of green energy. Gasification technology has been widely investigated since it provides output gaseous fuel known as producer gas (PG). The aim is to produce alternative renewable gas fuel to replace natural gas. This goal, however, is not attainable when using air as the gasification agent due to the severe dilution with N2. To overcome the N2 contamination in PG, steam can be used as the gasification agent. The main obstacle for steam-gasification is the highly endothermic reaction nature. This study investigated biomass steam gasification in a new medium-scale annular reactor design with gas heating jacket. This experimental study used two steam injection configurations: bottom and top. Temperature varied in the range of 300-600°C for first configuration, while steam to biomass (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°C) and reduced S/B ratio in the range of 1.3-2.2. Highest H2% was 44% at the best steam flow rate of 30 g/min with HHV of 12.8 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 hydrogen production was also investigated. H2% was 47.7% for CSC, followed by 46.3% for PKS and 44.7% for EFB. Finally, the sustainability of the reactor was tested by switching from LPG heat input start-up into PG fuel. The reactor was not able to sustain the operation at maximum temperature when using 100% PG fuel. Therefore, the reactor was tested with air flow to provide a small portion of the heat input in air-steam gasification mode. The reactor was characterized in air-steam gasification mode using 4 air flow rates of 25, 50, 75 and 100 LPM flow rates