Characteristics of cardboard and paper gasification with CO_2

摘要

Evolutionary behavior of syngas chemical composition and yield have been examined for paper and cardboard at three different temperatures of 800,900 and 1000 ℃ using CO_2 as the gasifying agent at constant flow rate. Specifically the evolution of syngas chemical composition with time has been investigated. Pyrolysis of the sample was dominant at the beginning of the gasification process as observed from the high initial devolatilization of the sample followed by char gasification of material to form syngas for a long period of time. Results provided the role of gasification temperature on kinetics of the CO_2 gasification process. Increase in gasification temperature provided increased conversion of the sample material to syngas. Thus the sample conversion to syngas was low at the low temperature of 800 ℃ while at elevated temperatures of 900 and 1000 ℃ substantial enhancement of the kinetics process occurred. The evolution of extensive reaction rate of carbon-monoxide was calculated. Results show that increase in temperature increased the extensive reaction rate of carbon-monoxide. The global behavior of syngas chemical composition examined at three different temperatures revealed a peak in concentration of H_2 to exhibit after few minutes into the gasification that changed with gasification temperature. At 800 ℃ gasification temperature peak in H_2 was displayed at 3 min into gasification while it decreased to only 2 min, approximately, at gasification temperatures of 900 and 1000℃. The effect of reactor temperature on CO mole fraction has also been examined. Increase in the gasification temperature enhances the mole fraction of CO yields. This is attributed to the increase in forward reaction rate of the Boudouard reaction (C + CO_2 ←→ 2CO). The results show important role of CO_2 gas for the gasification of wastes and low grade fuels to clean syngas.