Combustion performance and exhaust emission analysis of spent bleaching earth (SBE) oil as burner's fuel

Abstract

Spent bleaching earth (SBE) is a type of hazardous solid waste generated during the bleaching process of crude palm oil (CPO). Despite years of studies being done on how best to manage the waste, the issue is still largely unsolved and has created massive economic and environmental problems. SBE is generally disposed by dumping onto landfills because it is by far the cheapest method. However, due to the high quantities of water insoluble substance; mostly free fatty acids (FFA) and peroxide as well as heavy metals, the waste decomposes very slowly and thus becoming a serious hazard to the environment that can cause water and soil pollution as well as fire risk. Recent breakthrough in studies have allowed significant amount of residual oil contained in SBE to be extracted and this has opened up new avenues to tackle the SBE dumping issue. By extracting the oil, it can be used as an alternative fuel in lieu of fossil fuels in power generation. This will inadvertently create a value added product that can mitigate the environmental hazards of SBE dumping but also reduce the cost of handling and disposing the waste. However, at present the research on SBE is limited to the advancement of residual oil extraction technique. There is no research that focus on the evaluation of SBE oil as a substitute to fossil fuels. As such this paper will evaluate and determine the combustion performance and exhaust emission of SBE oil as a source of fuel for burner. The combustion performance in terms of CO2, CO, NOx and flame temperature will be compared with neat diesel under the same conditions. SBE oil shows some promising combustion performance, since it produces no SOx due to the absence of Sulphur, emits lower CO2 than diesel, while releases higher CO than diesel. The higher amount of CO produced by SBE oil can be largely attributed by the high viscosity of the oil. The high viscosity and density of SBE oil greatly affects the fuel spray which in turns causing a poor atomization and combustion hence the high amount of CO emission.