Optimization of Biomass Use and Performance as an Industrial Fuel:

Abstract

The main focus of this research is to evaluate the combustion characteristics ofbiomass fuel, macadamia nut shells. It seeks to determine its optimum combustionby designing a biomass burner with provision for measurement and then evaluatingthe combustion behaviour of the macadamia shells using the burner. The researchalso sought to determine the physical and chemical properties of the macadamiashells as factors that may a_ect combustion.The analysis for the properties of the macadamia nut shells, determined that ithas a higher heating value of 21.12 MJ/kg, 72.1% volatile matter, 13.1% moisturecontent, 1.6% ash and 13.1% _xed carbon. In addition, further analysis evaluatedthe carbon, hydrogen, nitrogen, sulphur and oxygen compositions as 54.5%, 5%,0.36%, 0.02% and 39.8%, respectively. These analyses show that macadamia shellshas a high heating value with low ash content which are suitable qualities for anindustrial fuel.An experimental rig was designed, constructed with a special fuel feeding screwand used in this research to enable the combustion of the macadamia nut shells.The instruments connected to the rig included thermocouples, ori_ce-meter, andemission gas analyzer. An Adventest TR2724 multichannel temperature recorderwas used to acquire and record temperature data from the thermocouples to andaccuracy of _ 0.5oC in the system.The combustion parameters, viz, combustion chamber temperature and gaseousemissions, were determined by varying the rate of fuel feed rate and the amount ofcombustion air per unit time. It was found that an air fuel ratio of 2.4 kg of airfor a unit kg of fuel gives the optimal combustion chamber temperature of 800 oC,with acceptable gaseous emissions of; Carbon monoxide (CO), Nitrogen monoxide(NO), Nitrogen dioxide (NO2) , and Sulphur dioxide (SO2). The results of this studyprovides an insight for future design of biomass systems to be used in small scaleindustries locally