Effects of carbonisation temperature on charcoal from some tropical trees

Abstract

The high cost of conventional fossil fuels has resulted in a rise in the demand for charcoal in developing countries. There has been a problem of wood scarcity and indigenous tree species are being replaced with the fast-growing, short-rotation species. Three short-rotation tree species: Gliricidia sepium, Leucaenea leucocephala and Gmelina arborea were converted to charcoal by a pyrolytic process. The effects of final carbonisation temperature on the yield, heating value and proximate analysis of charcoal from the tree species were determined. Gliricidia sepium gave the highest charcoal yield of 51.6% with a gross heating value of 31.45 MJ/kg at 300°C final carbonisation temperature. There was no significant difference in the charcoal yield of Gmelina arborea and Leucaena leucocephala at 5% level of testing. The charcoal yield decreased with an increase in carbonisation temperature. The percentage volatiles in charcoal decreased with an increase in temperature, while there was an increase in the percentage fixed carbon.