Production and Evaluation of Fuel Characteristics for Briquettes from Different Crop Residues

Abstract

Briquettes were produced from selected crop residues namely groundnut shells, maize cobs and an ad-mixture of both (composite). The performance characteristics of the briquettes were then evaluated based on fuel efficiency, cooking efficiency, time taken to boil water and fuel consumption rates respectively. The residues were reduced to 2mm particle sizes with a hammer mill and a set of sieves. Gum arabic and water were added in measured quantities based on a design ratio and thoroughly mixed into a thick paste which was fed into a manually operated briquette mould to produce perforated cylindrical briquettes that were sundried into hard pans. The design ratio of dry matter: gum arabic: water was; for type A (maize cob briquettes) 2:0.8:7, for type B (groundnut shell briquettes) 1.2:0.25:3.5 and for type C (composite briquettes) 1.6:0.5:5.5. A laboratory determination of gross calorific value was carried out and the following values were obtained; type A:-,40.924MJ/Kg, type B:-,25.757MJ/Kg and type C:-,39.656MJ/Kg. A specie of firewood, delonix regia wood labelled type D which was used for comparison was found to have a calorific value of 24.340MJ/Kg. On evaluation, the four fuel types A, B, C and D showed fuel efficiency values of 38%, 62%, 41% and 27% respectively. In the same order, cooking efficiency values were estimated to be 14%, 23%, 11% and 10%. In boiling equal volumes of water, it took type A an average of 15mins, type B 20mins, type C 24mins and type D 58mins. Lastly, the rate of fuel consumption was 1.65Kg/hr, 1.14Kg/hr, 1.00Kg/hr and 0.9Kg/hr for types A, B, C and D respectively. Conclusively, it was observed that briquettes produced from selected residues are better substitutes and alternative energy sources compared to wood.