CO₂ gasification behavior of biomass chars in an entrained flow reactor

Chars of different particle sizes (150–250, 500–600 μm) from two different biomass species (spruce and coconut shell) were gasified under entrained flow condition in the presence of CO₂ at different temperatures (800, 900 and 1000 °C). The concentration of CO₂ was also varied between 5 and 20 % to determine its effect. It was found that significant improvement in gasification efficiency is possible by lowering the particle size below 0.5 mm. This finding was attributed to the spruce char as it showed the highest (≈50 %) conversion for the lowest particle size. It was also revealed that less reactive chars (coconut shell) were insensitive to the particle size and temperature variation for CO₂ as a gasifying agent. Generally, pyrolysis process dominates the conversion process during raw biomass gasification. No tar component was observed during gasification at 1000 °C. As a whole, this study provides useful insight about the entrained flow gasification process of biomass chars with CO₂.