Biomass gasification in an autothermal semi-industrial fluidized bed gasifier: Syngas characterization and energy balance

Biomass gasification is well-established in industrial applications, but semi-industrial autothermal systems remain underexplored despite their role as a bridge between laboratory scale and full-scale deployment. Understanding syngas characteristics, energy recovery, and system efficiency at this scale is critical for optimizing industrial gasification. This study examines air gasification of woody biomass in a 200 kW autothermal bubbling fluidized bed gasifier operating at equivalence ratios (ER) 0.22-0.45 with recorded bed temperatures of 695-860 degrees C. Key performance indicators, including syngas composition, lower heating values (LHV), cold gas efficiency (CGE), carbon conversion efficiency (CCE), and energy distribution of the near-industrial system, were analyzed. Results show syngas primarily contained H2 (6.4-11.3 %), CO (8.5-16.6 %), CH4 (3.0-5.5 %), and CO2 (15.6-19.4 %), with LHV of 3.9-7.1 MJ/Nm3. CGE reached 51.8-71.4 %, and CCE 78.6-98.5 %. Overall system efficiency (79-93 %) highlights the role of energy recovery from syngas cooling and gathered solid residues in improving large-scale gasification viability. This study provides novel insights into optimizing semi-industrial gasification, demonstrating the feasibility of integrated energy recovery for enhanced efficiency and sustainability.