NC State
BioResources
Chen, D., Zhou, J., Zhang, Q., Zhu, X., and Lu, Q. (2014). "Upgrading of rice husk by torrefaction and its influence on the fuel properties," BioRes. 9(4), 5893-5905.

Abstract

Torrefaction refers to thermal treatment of biomass at 200 to 300 °C in an inert atmosphere, which may increase the heating value while reducing the oxygen content and improving the storability. In this study, the effects of torrefaction temperatures on the properties of rice husk were analyzed. Torrefaction experiments were performed using a lab-scale device designed to reduce heat and mass transfer transient effects. A new method is described for clarifying torrefaction time and minimizing experimental error. Results from analysis of torrefaction temperatures (200, 230, 260, and 290 °C) support the supposition that the fiber structure is damaged and disrupted, the atomic oxygen ratio is reduced, the atomic carbon ratio and energy density are increased, the equilibrium moisture content is reduced, and the hydrophobic properties of rice husk are enhanced. The data presented in this paper indicate that torrefaction is an effective method of pretreatment for improving rice husk. Torrefaction at 230 to 260 °C for 30 min was found to optimize fuel properties of the torrefied rice husk.
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