Production of low-tar syngas by gasifying corn stalk in a fluidized bed two-stage system using CO2-containing reagent

• CO 2 -rich gasifying agent was used to gasify corn stalk in a fluidized bed two-stage system. • CO 2 can be reduced/ reformed by the pyrolytic products to realize its chemical capture. • CO 2 as a component of products can reduce the introduction of N 2 , improving the quality of the obtained gas. • Tar content in producer gas gradually decreased and reached near 0 g/Nm 3 after reaction for 30 h. A fluidized bed two-stage gasifier was employed to gasify corn stalk using a CO 2 -rich gasifying agent for gas production. This study examined the performance when utilizing CO 2 and H 2 O as substitutes for a portion of N 2 in the gasification medium, contrasting to the air gasification way. Within the framework of a fluidized bed two-stage gasifier, CO 2 , serving as a reactant, can be reduced or reformed by the products of pyrolysis. Concurrently, the presence of CO 2 in the product stream serves to reduce the contamination of N 2 , thereby enhancing the quality of the resultant gas. The comparative experimental findings reveal a significant enhancement in the H 2 and CO within the product gas, accompanied by an increase in the H 2 /CO (v/v) ratio. The lower heating value (LHV) of the producer gas is also rising from 6.38 to 7.05MJ/Nm 3 d while the tar content is plummeting from 0.86 to 0.21 g/Nm 3 d . In an extended 50-hour continuous operational test, the tar content in the producer gas is progressively diminished, reaching near 0 g/Nm 3 d after 30 h of reaction. The research indicates that such a fluidized bed two-stage gasifier with a CO 2 -rich gasifying agent not only demonstrates remarkable stability throughout its continuous operation but also shows technical viability in the generation of a low-tar syngas.