Torrefaction of Durian Skin Waste Under Mild Pressurization Technique for Various Temperatures

In recent years, biomass has emerged as a promising alternative energy source, characterized by its inherent flexibility and accessibility. Despite this, the direct application of biomass is deemed unsuitable owing to its low quality as a fuel source. In the present study, durian skin waste (DSW) was torrefied using a new method called mild pressurization technique. Unlike the conventional method, this technique offers an advantage in terms of reducing the operational cost by eliminating the use of costly inert gas throughout the process. This study examined the effects of varying temperatures (250, 275 and 300 °C) on the physicochemical and combustion characteristics of DSW while maintaining constant residence time of 30 min throughout the process. The findings demonstrated that torrefaction temperature significantly influences the performance of torrefied DSW. Specifically, both mass yield and energy yield exhibited a substantial decline with rising temperatures. However, higher temperatures led to improvements in the higher heating value (HHV), with the HHV increasing from 19.90 to 23.01 MJ/kg as the temperature increased from 250 to 300 °C. Next, regardless of temperature, most of the results of the torrefied DSW meet the international standards, except for ash content and the HHV at 250 °C. Nevertheless, when compared to the commercial coal, the ash content and the HHV at 250 °C remain competitive. Overall, these findings demonstrate the potential of torrefied DSW as a promising coal substitute, thereby contributing to reduced reliance on fossil fuels and decreased greenhouse gas emissions.