Governing Parameters of Syngas Quality in Fluidized-Bed Biomass Gasification

Biomass gasification in fluidized-bed reactors offers a versatile pathway for converting renewable feedstocks into energy-rich syngas, benefiting from intense gas–solid mixing and high heat and mass transfer rates. However, the strong coupling between feedstock properties, hydrodynamics, and operating conditions makes process optimization inherently complex. This critical review examines the governing parameters of fluidized-bed biomass gasification and their influence on syngas quality and process performance. Evidence from the literature was organized and comparatively assessed with emphasis on reactor temperature, pressure, equivalence ratio, biomass physicochemical characteristics, gasifying agent, and fluidization behavior. The comparative evidence shows that temperature responses depend on the operating window, while changes in gasifying agent and equivalence ratio can alter both combustible gas concentrations and dilution. Biomass characteristics and pressure introduce additional constraints, and minimum fluidization velocity provides a hydrodynamic reference for stable bed operation. The heterogeneous data do not establish a universal ranking of parameter sensitivity. Across the compiled conditions, the heating value of the producer gas was strongly and negatively associated with its N2 content (r = −0.89), a pattern consistent with dilution but obtained from studies that also differ in feedstock, gasifying agent and reactor; equivalence ratio was the only parameter whose effect had the same sign in every within-study comparison. Overall, effective fluidized-bed gasification requires the integrated control of feedstock, operating, and hydrodynamic conditions. Understanding these interactions provides a rational basis for optimizing syngas quality and improving the energetic performance and operational stability of biomass gasification systems.