Abstract:
Rice bran is a biomass residue that is produced in large quantities in the rice growing regions of Nigeria. It is a good source of fuel and its rate of generation is huge; yet it is found as wastes at rice mills, rice fields and other processing centres. This has caused a disposal problem leading to environmental pollution. Rice bran briquette serves as an alternative method to solve the residual disposal problem and reduce the consumption and dependency on fuel wood to the barest minimum. Three grades of cylindrical briquettes with central holes were produced using cassava starch as binder, each in the percentage ratio 1:9, 2:8, 3:7, 4:6 and 5:5 of palm kernel shell to rice bran respectively. The briquettes were formed in the mould of an existing manually operated briquette machine having efficiency of 85 % at an optimum pressure of 3 MPa. After series of tests on the different mixing ratios, the experiments revealed that the maximum heating values were for the 30 % of palm kernel shell and 70 % of rice bran at 10 % binder level. Moreover, all characterization and tests were based on this mixing ratio. Characterization was done through proximate and ultimate analysis in which the percentage volatile matter, percentage ash content, percentage fixed carbon, moisture content and the heating value were all determined with different sizes of palm kernel shell in the mixture (2, 4 and 6 mm diameter). The higher heating value obtained from the experiment was 14.25 MJ/kg and the heating value increases with decreasing grain size of palm kernel shell. Tests showing the effects of binder level, particle sizes and compaction pressure on the burning rate of the briquette were also carried out. The briquette performance was evaluated compared to firewood through water boiling test which showed that 1 kg of the briquette took 15 minutes to boil 2 litres of water where as it took 1.2 kg of firewood 21 minutes to boil the same quantity of water.
