Impact of torrefaction on fuel property of tropical biomass feedstocks.

Abstract

Biomass in its natural form is characterized by poor ignition quality, excessive smoking and low combustion efficiency when used as energy source in boilers and blast furnaces. In this paper, the effect of torrefaction on the characteristics of tropical biomass feedstocks (rice husk, groundnut shell and corn cob) at different torrefaction temperatures (200, 250 and 300_C) were investigated. The result of biomass weight loss as a function of temperature variation revealed that at relatively low torrefaction temperatures of 200 and 250_C the weight loss were very pronounced when compared to the negligible weight loss at a torrefaction temperature of 300_C. Rice husk and corn cob exhibited a higher weight loss during torrefaction due to high degradation of the hemicelluloses inherent in the feedstocks. The oxygen:carbon of the torrefied biomass deduced from the ultimate analysis revealed a low and concentrated distribution in the Van Krevelin plot compared to the raw feedstocks. The thermogravimetric analysis of the feedstocks shows that the thermal stabilities were in the decreasing order (groundnut shell > corn cob > rice). The spectral analysis result for torrefied biomass samples showed that the intensity of the functional group peaks increased with increase in the torrefaction temperatures.