Experimental investigation of circulating fluidized bed combustion of dry powders of coal slime

Effective combustion of coal slime in circulating fluidized bed (CFB) boilers is essential for the sustainable development of clean coal technology. To overcome issues related to burning wet coal slime in CFBs, we propose to dry coal slime in a low-temperature drying system and burn the dried fine powders in a CFB with a highly efficient separator. This study reports a series of experiments conducted in a 4MWth pilot-scale CFB combustion test facility to assess the feasibility. The results demonstrate that the dried slime particles, which have a particle size distribution similar to that of circulating ash particles, can be burned stably, efficiently, and cleanly. The combustion of fuels with size distributions similar to that of circulating ash particles increases solids circulation rates, betters solids concentration distribution, enhances heat transfer combustion and improves operation and SO2 and NOx controls. Therefore, the study presents a potential opportunity to advance CFB combustion technology.