Study On Grade Recovery Of Low-Temperature Flue Gas Waste Heat From CFB Boiler

Circulating fluidized bed (CFB) boiler develops rapidly during these years. Low-temperature flue gas and highly efficient boilers pursued by power-plant boiler designand operation promotion, large heat exchange area and acid dew point corrosion still existin flue gas heat recovery. Promotion of heat-pipe exchangers and furnace desulfurizationtechniques creates conditions for in-depth CFB boiler flue gas heat recovery.Taking as subjects the CFB boiler units in Shanxi Jingyu Power Generation Co., Ltd.(Jingyu Plant) and Tangshan Kailuan East Power Co., Ltd.(Dongfang Plant) as subjects,this thesis proposes the low-temperature waste heat grade recovery. First, recoveryprocess parameters are confirmed based on the flue gas property, the associated attributesamong parameters such as moisture content, smoke acid dew point and the gastemperature, considering the dust-eliminating efficiency. Secondly, models of smokewind resistance, wind electrical energy consumption and net efficiency are built based ona single-stage low-temperature flue gas heat recovery system (RGCFB). Analysis ofthermal efficiency and net efficiency in four conditions showed that: compared with CFBboiler, RGCFB boiler improved the thermal efficiency by1.28~2.23%and the netefficiency by0.51~1.18%. Finally, analysis was made on the energy-saving potential ofthe in-depth grade recovery system (CCFB), whose theoretical analysis model was builtwith the heat method and the equivalent enthalpy drop method. Calculation showed thatunder design and operating conditions, thermal efficiency of the CCFB boiler increasedby1.78%and1.39%, saving10.489g/(kW·h) and10.619g/(kW·h) standard coal.Research results showed low-temperature waste heat recovery installation wasmarkedly energy-saving and that net efficiency was an accurate evaluation index of boileroperation. The results provided theoretical basis and technological support for the processpromotion of condensing CFB boiler unit.