Biocoal production from selected plant wastes through torrefaction

Abstract

Torrefaction is a thermal treatment process that embroils the roasting of biomass in a low oxygen environment. It is principally exploited to produce a biofuel called torrefied biomass or biocoal. Torrefaction improves fuel characteristics and reduces emission. Corn Stalk (CS), Rice Husk (RH), Mesocarp Fibre (MF) and Palm Kernel Shell (PKS) were used for studying the torrefaction of plant wastes, preparation and performance characterization of biocoal. Torrefaction was conducted using a muffle furnace at temperature of 250⁰C for 20 minutes and resulting samples were milled to fine particles. Samples of different ratios were prepared (CS:RH:MF:PKS (10:20:30:40), (20:30:40:10), (30:40:10:20) and (30:40:10:20) using corn starch as the binder. Manual briquetting machine was used to compound the mixture into solid shapes and subjected to Physicochemical and combustion properties to determine the moisture content, ash content, fixed carbon content, volatile matter, bulk density, heating value, time to ignite, burning time with burning temperature respectively. The properties of biocoal were compared with that of wood to access their potential as a renewable energy source. The result for the Physicochemical properties shows that the moisture content ranged from 15.64 to 24.88%; volatile matter (20.00 to 71.00), ash content (7.00 to 26.50%), fixed carbon (2.86 to 35.96%) and bulk density (1.16 to 1.92); for the physical properties; time to ignite ranged from 19.33 to 72.15secs, burning time (1039.58 to 2347.89secs), temperature (59.89 to 273.80⁰C) and heating value (3080.79 to 4484.11). Sample CS:RH:MF:PKS with ratio of 30:40:10:20 have the best Combustion and Physicochemical properties.