Performance evaluation of a small scale palm fruit biomass-fired autoclave boiler

Abstract

Different fuel mixture (empty fruit bunch, fiber and shell from palm kernel) at different ratios were used to fire an existing boiler to determine the most efficient fuel mixture composition for an improved performance of the boiler. This was carried out to determine the effects of the different types of fuel mixture (at different proportions) on the steam temperature, pressure, rate of steam production and boiler efficiency of the boiler. It was discovered that fuel mixture with higher percentage of fibre cum palm-kernel shells produced the best results for high combustion rate and steam generation. The result of the steam temperature, pressure and enthalpy results for all the fuel combinations ranges between 141 to 161°C, 3.7 to 6.34 bar, and 27.351 to 27.591 MJ kg-1, respectively. Fuel combination ratio 1:8:1 produced the best result in terms of rate of steam generated while the fuel mixture ratio 1:2:7 produced the highest value for boiler efficiency (74.2%). The boiler consumed more fuel with combinations that have high percentage of fibre content (2:7:1) due to the physical and combustion properties of fibres but fuel combinations with higher shell content in the mixture (1:1:8) burns longer in the combustion chamber than mixtures with higher percentages of other fuel. The fuel mixtures produced high temperatures with ranges of 602 to 738°C for processing operation which indicated the suitability of these fuels as good potentials for boilers. These results indicates that preparation of the waste product from palm oil processing as fuel to fire the boiler have the capacity to supply the energy required in the mill in order to boost the extraction efficiency and oil quality of the small scale palm fruit processors upon incorporation into their process line.