Effects and countermeasures of CO2 content in biogas on performance of biogas stove

The thermal performance of a typical domestic biogas stove supplied with biogas of different CO2 volume fractions was investigated. Possible technical measures in response to variations in biogas composition were studied as well. Mixed gas of natural gas and CO2 were produced so as to simulate the biogas in which CO2 volume fraction varied from 50% to 30%. With the decrease of CO2 percentage in the mixture, it was found that heat output, heat efficiency and CO emission increased, while NOx emission did not change significantly. When heat output was greater than 3.26 kW, the current testing method could not reflect the relationship between thermal efficiency and CO2 ratio exactly. Variations in the CO2 content in biogas significantly affected the thermal performance of the biogas stove, which maight increase complaints and security risks. When the volume fraction of CO2 was less than 40%，regulating the biogas pressure according to the CO2 content so as to stabilize heat output could significantly improve the CO emission, which may be regarded as a measure to cope with variations of CO2 content in biogas.