Improvement of Higher Heating Value and Hygroscopicity Reduction of Torrefied Rice Husk by Torrefaction and Circulating Gas in the System

Abstract

This study aimed to enhance the thermal characteristics of rice husk biomass through torrefaction conducted in a fixed-bed reactor. A novel approach was employed by circulating the gas produced within the system, instead of using traditional nitrogen. The torrefaction process took place at temperatures ranging from 200 to 320 °C, with different residence times of 10, 20, and 30 min for heat exchange. Quantitative analysis of the torrefied biomass revealed several notable improvements. The higher heating value of the biomass increased significantly, reaching 23.69 MJ/kg at a temperature of 320 °C and a residence time of 30 min. This enhancement indicates the effectiveness of torrefaction in increasing the energy content of the biomass. Furthermore, the torrefied biomass exhibited a remarkable reduction in hygroscopicity, with reduction by as much as 92 wt% compared to raw rice husk biomass. This reduction implies that the torrefied biomass is more resistant to moisture absorption, making it more stable and suitable for various applications. The torrefaction process in the fixed-bed reactor yielded a torrefied biomass with a production yield of 76 wt% (RH-320, RT30). This yield showcases the potential of the employed technique for producing a substantial amount of high-quality torrefied biomass. The resulting biomass holds great promise for diverse applications. It can be utilized for industrial steam production, contributing to the efficient use of biomass resources. Moreover, it could serve as an alternative fuel source for biomass power plants, offering a sustainable energy solution. Overall, this study demonstrates the effectiveness of the proposed torrefaction method in enhancing the thermal characteristics of rice husk biomass. The improved energy content and reduced hygroscopicity make torrefied biomass a valuable resource for various industries, promoting the utilization of biomass as a renewable energy source.