Combustion characteristics of spent coffee ground mixed with crude glycerol briquette fuel

This research focused on the combustion of spent coffee ground (SCG) mixed with crude glycerol briquette fuel for different SCG: crude glycerol mass ratios of 100:0, 95:5 and 90:10. The initial supplied air to burn the briquettes was varied at 550%, 700%, 850% and 1000% theoretical air and the combustion temperature in a designed chamber and exhaust gases were monitored. The results showed that crude glycerol and amount of air influenced the combustion of the briquette. The temperature and rate of combustion increased when crude glycerol was increased. In addition, it was found that to burn a high-density briquette, the supplied air should be higher than 500% theoretical air. The composition of the exhaust gases, namely carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2) and acrolein gas were are all within MCP, ELVs and REL-STEL (NIOSH) Standards. The results showed that the best ratio of 90:10 can be recommended to be used as fuel with 850% theoretical air.