SIMULATION OF THE GAS TEMPERATURE DEVIATION IN LARGE-SCALE TANGENTIALCOAL-FIRED UTILITY BOILERS

For tangential coal fired boilers, the gas temperature deviation at th e exit of the furnace will occur when boiler capacity becomes large. I n this paper, the now, heat transfer and combustion process in a boile r of 300 MWe unit at Shiheng Power Plant, Shandong, China and a boiler of 600 MWe unit at Shidongkou Power Plant, Shanghai are simulated. Th e causes and decrease ways of the gas temperature deviation are invest igated. It is found that the gas temperature deviation results from th e after twirl and the platen superheater. Decreasing the diameter of t angential circle formed by secondary air flow can result in the decrea se of temperature deviation to a certain extent. Although the after tw irl can be decreased by opposing the tangential direction of some seco ndary air flows, the flow field in the furnace might be disturbed, and the temperature deviation might be increased, if the momentum and the angle of the opposite secondary air now are not appropriate. (C) 1998 Elsevier Science S.A.