Air-CO2 and oxygen-enriched air-CO2 biomass gasification in an autothermal downdraft gasifier: Experimental studies
2022
Pandey, Bhoopendra | Sheth, Pratik N. | Prajapati, Yogesh K.
The mounting CO₂ emission and rapid depletion of fossil fuels are two significant challenges for sustaining growing energy requirements and keeping the environment clean. Biomass gasification using CO₂ as a gasifying agent may be one of the alternative techniques to tackle such emerging problems. CO₂ behaves as an inert gas at low temperatures and can be converted to CO at high temperatures. In the present study, air-CO₂ and oxygen-enriched air-CO₂ biomass gasification are successfully conducted in the autothermal reactor. The impacts of varying concentrations of CO₂ and oxygen in the gasifying agent on the performance of the gasifier are analyzed. The CO₂ content in the gasifying agent is varied from 0 to 45 vol% at two different oxygen concentrations (21 and 35 vol%). The reactor used is an Imbert-type downdraft gasifier with a thermal capacity of approximately 10 kW. The results reveal that the yield of CO in the producer gas increases compared to air gasification resulting in a higher heating value of the producer gas. However, the average temperature in the gasifier reduces with increasing CO₂ percentage in the gasifying agent. Upon increasing the O₂ fraction from 21 to 35 vol%, while keeping 30 vol% CO₂ content constant, CO content is found to upsurge from 23.96 to 31.37 vol%. The inclusion of CO₂ inside the gasifier promotes the endothermic Boudouard reaction that causes the conversion of CO₂ into CO.
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