PHYSICAL, MECHANICAL AND COMBUSTION CHARACTERISTICS OF BAMBOO (BAMBUSA VULGARIS) CHARCOAL IN COMPARISON WITH THREE OTHER INDIGENOUS WOOD CHARCOALS

Abstract

ABSTRACT Charcoal is a carbonaceous solid with a fixed carbon content of 70% or more. Wood charcoal is processed by heating wood materials in a low-oxygen environment.Bamboo (Bambusa vulgaris) is a woody material composed of hemicelluloses, cellulose and lignin that can produce higher value-added products by pyrolysis processes with low ash content. This study investigated the energy potential of bamboo (bambusa vulgaris) as an alternative charcoal material in comparison to indigenous wood in terms of mechanical and combustion properties. Bamboo and three other wood species Teak (Tectona grandis), Afara (Terminalia superba) and Omo (Cordiamillenii) were dimensioned for mechanical properties’ determination using ASTM standards. All samples were carbonized in a portable laboratory kiln at 400oC to charcoal. Combustion characteristics were determined for the carbonized samples using standards of the ASTM, while Fuel Value Index (FIV), Modulus of Rupture (MOR), Modulus of Elasticity (MOE) and Compressive Strength (COMP) were obtained for all the samples and comparedusing ANOVA at 5% significant level. Results from proximate analysis showed that charcoal from Volatile Matter values ranged from 20.0 to 25.95% with Teak Charcoal(TC) having the highest value and Bamboo Charcoal(BC) with 22.70%. The calorific value ranged from 2.300 to 2,725 kcal/kg. The BC with 2,500 kcal/kg was not significantly (p>0.05) different from TC with 2,725kcal/kg. The ash content for all charcoal types ranged from 2.2 and 2.68% with BC having the highest ash content. The percentage fixed carbon for the species ranges from 66.75 to 72.25%, with ANOVA revealing no significant (p < 0.05) differences between all charcoal types. The Nitrogen and Sulphur contents ranged from 0.07 to 0.13% and 0.09 to 0.11%, respectively. The BC had the highest values for both properties, however, there were no significant (p > 0.05) differences for all charcoal types. The hemicellulose and cellulose contents ranged from 0.4 to 1.2 and 0.3 to 0.5%, respectively. The BC had the highest values of hemicellulose and cellulose contents with the lowest extractive percentage compared to other woody materials. Mechanical test revealed that MOE values ranged from 110.0 to 501.7 N/mm2 with BC having the least value and TC gave the highest value. The MOR and COMP values ranged from 4.8 to 187.2 N/mm2 and 3.3 to 18.7 N/mm2,respectively, while the hardness values for all samples ranged from 11 to 61.4N and the FVI ranged from 3733 to 14140. Bamboo charcoal had lowest values for all mechanical properties studied due to its morphological structure compared to the other tree species but has a higher potential as source of fuel due to its high calorific value, fixed carbon and oxygen contents comparable to Teak and Afara wood charcoal. The combustion property of Bamboo charcoal is higher while its mechanical property is lower as compared to other wood charcoals.