Performance of Some Biocoal Briquettes Produced from Mixture of Sawdust and varying Nigeria Coals as Composite Domestic Fuel

Abstract

Performance evaluation of biocoal briquettes from three different coal mines in Nigeria mixed with sawdust as composite domestic fuel was carried out. Samples of coals collected from Owukpa, Okpara, and Onyeama mines were pulverized and blended with sawdust at various constituent ratios of coal/sawdust of 0.0/100, 10/90, 20/80, 30/70, 40/60, 50/50 and 100/0.0. Cassava starch was used as binding material while calcium hydroxide was used for desulphurization. Tests carried out included proximate analyses, ultimate analyses, and performance analyses. Results showed that fixed carbon in all the coal samples ranges from the highest fixed carbon of 63.81% for Okpara (OK) to the lowest of 62.87% for Owukpa (OP 70/30 ) while sawdust was 21.03%. The Onyeama Coal has 1.25% ash content compares with 5% for Owukpa. Onyeama coal contains the highest volatile matters of 29.61% while Owukpa biocoal briquette (OP 50/50 ) has the highest percentage heat utilization of 88.61 and lowest specific fuel consumption of 0.31kg/kg.  Onyeama coal (ON 90/10 ) has the highest calorific value of 33.25 MJ/kg. The addition of sawdust in the biocoal briquettes resulted in lower volatile matter, low hydrogen, high percentage heat utilized and low specific fuel consumption. Keywords- Biocoal briquette, sawdust, proximate analysis, ultimate analysis, fixed carbon