A study of Biocoal from Torrefaction of Some Selected Plant Residues
1*Onifade T. B. and 1Jekayinfa S. O.
1Department of Agricultural Engineering, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
DOI: 10.36108/laujoces/5202.51.0151
Abstract
Torrefaction process of four different agricultural residues in Nigeria was carried out. Torrefaction is a thermal conversion process that involves the treatment of biomass at temperature between 200-300 oC in an oxygen reduce atmosphere. Torrefaction improves fuel characteristics and reduce emission. Groundnut Shell (Gns), Sugarcane Baggase (Sb), Mango Pod (Mp) and Cashew nut Shell (Cns) were used for studying the torrefaction of plant residues, preparation and performance characterization of biocoal. Torrefaction was conducted using a muffle furnace at temperature 250 oC for 20 minutes and resulting samples were milled to fine particles. Samples were prepared at various constituent ratios: (Gns 100%, Sb 100%, Mp100%, Cns 100%, Gns/Sb/Mp/Cns (15:20:30:35), Gns/Sb/Mp/Cns (20:30:35:15), Gns/Sb/Mp/Cns (30:35:15:20) and Gns/Sb/Mp/Cns (35:15:20:30) and cassava starch was used as the binder. Manual briquetting machine was used to compound the mixture into solid shapes and subjected to physico-chemical analysis to determine the moisture content, ash content, fixed carbon content, volatile matter content, bulk density, heating value, time to ignite, burning time with burning temperature inclusively. The properties of biocoal were compared with that of wood to assess their potential as a renewable energy source. The results for the physico-chemical properties such as the moisture content, volatile matter, ash content, fixed carbon and bulk density ranges from 57.40 to 64.60 %, 44.18 to 75.69 %, 3.75 to 4.15 %, 2.67 to 34.59 % and 1103 to 1500 kg/m3 respectively. The results of the samples show that time to ignite, burning time, temperature and heating value ranges from 18.33 to 32.14 secs, 20.58 to 39.14 min, 50.80 to 2643.79 oC and 3170.79 to 4375.12 respectively. Sample of Gns/Sb/Mp/Cns with 30:35:15:20 ratio has the best physico-chemical properties.
Keywords: Biocoal briquette, Cashew nut shell, Groundnut shell, Mango pod, Sugarcane baggase, Torrefaction,