37. Reaction of Coal Ash with Added Fine Limestone in the Combustion

Three coals are subjected to combustion in the drop tube furnace. One kind of limestone, mixed with coal physically, is used for in situ simultaneous removal of SOx and halogen during coal combustion. The results show that SOx and halogen capture ability of added limestone varies with coal type and residence time. At a residence time of about 2.0s and the Ca/S molar ratio of ca. 2.0, a SOx removal of 89% and halogen removal of 50% could be achieved for Yanzhou with high Sulfur, while 50% SOx and 100% halogen removed for the other two coals. SEM-EDX results indicate that part of added calcium reacted with internal minerals to form Ca Al-Silicate or more complex compounds, which significantly decreases the calcium utilization efficiency.