Wet torrefaction pre-treatment of yard waste to improve the fuel properties

Abstract

The utilization of biomass has emerged as an attainable alternative for energy production. However, the intrinsic properties of biomass including hygroscopic behaviour, heterogeneity in structure and high moisture content constraint the usage of biomass in bioenergy applications. Wet torrefaction enhance the fuel properties of the lignocellulosic biomass by treating in hot compressed water. The present study aimed to identify the effectiveness of wet torrefaction to improve the properties of yard waste as an energy resource. Wet torrefaction operating parameters investigated in this study were water-to-biomass ratio (10:1–30:1) and reaction temperature (180–220 °C). The energy yield varies from 63.9% - 74.4% in these operating conditions. Temperature was found to have greater impacts on the fuel properties of biomass compared to water-to-biomass ratio. The higher heating value (HHV) of yard waste achieved was 24.2 MJ/kg after undergoing the wet torrefaction process at 220 °C with water-to-biomass ratio of 10:1. The enhanced properties for wet-torrefied biomass were observed as lower moisture content, lower ash content, higher fixed carbon content and higher heating value in relative to raw yard waste. Torrefied biomass had reduced oxygen content and higher carbon content in comparison with raw biomass, which implied that wet torrefaction is capable in improving the fuel properties.

Keywords

• Higher Heating Value (HHV)
• Mass yield
• Proximate analysis
• Response surface methodology (RSM)
• Wet torrefaction
• Yard waste