Combustion of a high ash and sulfur containing lignite in a pilot circulating fluidized bed combustor and its pollution characteristics

In this study a 50 kW circulating fluidized bed combustor (low velocity regime CBF combustor) was constructed for the combustion of high ash containing lignites. Beypazarý lignite which contains 45% ash and 3.72% sulfur was mixed with limestone and was burnt in this combustor. Emission characteristics were investigated at different Ca/S mole ratios. It was shown that SO2 removal efficiencies reached values of 98%. At an average bed temperature of 850°C NOx emission levels were found to be around 300 ppm however CO emissions were around 1466 ppm. Temperature variation along the combustor (of 1.8 m in height) was found to be about 140 and 90°C for two different feed points located at 0.17 and 0.52 m above the distributor and two different feedback points located at 0.37 and 0.17 m above the distributor, respectively.