DETERMINATION OF COMBUSTION PROPERTIES OF BLENDED BRIQUETTES OF SAWDUST, MAIZE STALKS, AND COFFEE HUSKS

Abstract

The tea industry in Kericho is among the main consumers of firewood for its intensive thermal energy demand used in industrial steam boilers. Concerns over firewood depletion have led tea producers to switch to alternate fuels for boilers. Briquettes made from biomass leftovers are among the possible options; however, they are not yet widely adopted and implemented. This study found a potential source of briquettes for fire boilers that will use agricultural byproducts produced in Kericho. The combustion properties of blended briquettes made from sawdust, maize stalks, and coffee husks were used to determine the optimal ratio. Among the primary reasons is the depletion of firewood, with a rise in the number of tea industry projects in Kericho County, resulting in an 8% reduction in forest cover. Blended briquettes have gained attention as a sustainable alternative to traditional fuels due to their potential for reducing environmental impact by utilizing agricultural and forestry residues and reducing the dependency on wood pellets. The physical properties investigated in this research included gross calorific value, moisture content, fixed carbon, and volatile matter of the blended briquettes. Experiment design and analysis were done using Design-Expert® Software Version 10-Stat-Ease.The response surface methodology was utilized to investigate how burning affects the physical properties of mixed briquettes manufactured from coffee husks, maize stalks, and sawdust. The interaction of the parameters was also explored. Blended briquettes were developed from coffee husks, maize stalks, and sawdust, measuring 45mm by 45mm by 35mm.From the analysis of individual briquettes, Individual briquettes' moisture content ranges from 10.01 % and 12.59%. Coffee husks gave 10.01%, Maize stalks briquettes 12.59% and coffee husks 10.01. The volatile matter is between 71.25% and 78.30% where sawdust gave 77.05%, coffee husks 78.30% and maize stalks 71.25%. The fixed carbons range between 8.58% and 13.08%. Sawdust gave 9.36%, coffee husks 8.58% and maize stalks at 13.08%. The Calorific Value is between 3.8652 kCal/g and 4.2149 kCal/g. Sawdust generated 4.1589 kCal/g, Coffee Husks 4.2129 kCal/g and maize stalks 3.8652 kCal/g. The optimal mix ratio of sawdust: coffee husks: maize stalks is 350:169.142:150. This ratio gives a moisture content of 9.65%, a gross calorific value of 4.356 kCal/g, a fixed Carbon of 6.986%, and a volatile matter of 79.115%. This has verified that blended briquette fuel has better combustion properties than individual samples. The knowledge gained from this research has contributed to the development of renewable energy technologies and supports the transition towards a more environmentally friendly and resource-efficient society.