Effect of atmosphere on torrefaction of oil palm wastes

Abstract: Torrefaction is a low temperature treatment for lignocellulosic biomass at lower temperatures between 473 K and 573 K under an inert atmosphere, which has been found to be effective not only for improving the quality of lignocellulosic solid fuels, such as their energy density and shelf life, but also to make them useful as a feedstock for further decomposition such as gasification and liquefaction. Although more than ten papers on this subject have been published in the last several years, in all of these studies, the atmosphere has been inert (nitrogen). When we try to utilize waste thermal sources, such as flue gas from boilers for torrefaction, the gas contains some components other than nitrogen such as oxygen, carbon dioxide and water vapor. The most serious problem is thought to be the existence of oxygen in the gas. In this study, torrefaction of Malaysian oil palm wastes was carried out in a fixed bed tubular reactor under oxygen/nitrogen flow at a temperature range of 494 to 573 K, in order to clarify the effect of oxygen on torrefaction of lignocellulose. The effects of torrefaction conditions such as atmosphere, temperature and time, on the torrefaction behavior were investigated. The lignocellulosic biomass wastes utilized were mesocarp fiber and kernel shell of oil palm, which are typical agricultural wastes in Malaysia