Combustion of Coal in Fluidized Bed: Performance Analysis

Fluidized bed combustion (FBC) technology has the potential to use alternative fuel sources such as coal, wood, or waste and it has the ability to reduce and control the emissions of oxides of nitrogen (NOx) and sulphur (SOx). This technology is capable of alleviating the energy problems of the Nigerian nation-a country with billions of tonnes of untapped coal and ironically with gross insufficient electrical energy supply. The aim of this research is to investigate the applicability of this technology to Nigerian low-grade coals (Enugu sub-bituminous coal). To achieve this, a pilot fluidized bed combustor of 3 m tall and 155 mm diameter was fabricated. The experiment was carried out using Enugu sub-bituminous coal of size 850 mu m. The effect of coal batch sizes was investigated by feeding the coal over-bed in batches of 0.15, 0.25, 0.35, 0.45 kg/batch. The bed and free-board temperatures were measured using digital thermocouples and the pressure drop was monitored using an orifice meter. The minimum fluidization velocity was obtained to be 1.64 and 1.91 m/s for a coal batch feed of 150 and 450 g respectively.