Investigation of Sludge Gasification under Flue Gas

This paper presents the study of sludge gasification under different model flue gases for supporting the development of dual bed gasifier. There are three model gases including 16%O2/N2, 16%O2/20%CO2/N2 and 16%O2/20%CO2/40%H2O/N2, as well as fly ash containing groups. The combustible gas yields were in the range of 247.8–417.3 L/kg sludge, the heating values of the producer gas were in a range of 2,881.8–6,617.3 kJ/m3, and the gasification efficiency were in a range of 46.43–74.56%. CO2 and H2O had beneficial effect on combustible gas yield, gasification efficiency, and LHV of the producer gas. CO content increased while the content of H2 decreased after CO2 introduction. When H2O was added into model gas with the ratio of 40%, H2 concentration in producer gas was remarkably increased as well as improved the overall yield, gasification efficiency, and thus resulting in a gas with a higher LHV. On the other hand, sludge fly ash added in the gasification atmosphere had a negatively effect on combustible gas yield, causing lower heating value of the producer gas. Based on the monitoring of gasification process, the LHV of produce gas can increase 2 to 3 times, possibly up to 17 MJ/m3 by controlling the proper reaction time. The findings can lead to the optimal design of gasifier and reaction to produce high value clean energy.