Improvement of the Energy Density of Rice Husk Using Dry and Chemical Treated Torrefaction

Abstract

The main objective of this present study was to investigate the Torrefaction process of lignocellulose biomass rice husk produced in Ethiopia through dry and chemical treated Torrefaction. Torrefaction is a technology that a partial pyrolysis of biomass which is carried out under atmospheric pressure in a narrow temperature range of 200-300°C and under an inert environment which yields higher solid yield than pyrolysis. Three different Torre faction temperatures 230, 255 and 280°C with three different holding times 20, 40 and 60 minutes were considered using dry and chemical treated torrefaction. The result showed that a net reduction of the volatiles content, mass yield, moisture content, bulk density and atomic oxygen content correlate with increasing torrefaction temperature and reaction time, while atomic carbon content, higher heating value (HHV), fixed carbon content and energy density increase with higher torrefaction temperatures in both treatment cases. So, torrefaction temperature and holding time had a significant effect on torrefaction process of rice husk. Based on the findings of this study, temperature of 280°C and 60 min for dry torrefaction and 280 with a residence time of 40 min for chemical treated torrefaction could be suggested for an effective and proper torrefaction process to recycle the agricultural biomass. The energy density of dry torrefaction was enhanced by 120% and chemical torrefaction was enhanced by 127.4%. Therefore, the torrefied biomass becomes fuel sources which can be applied to replace with fossil fuel.