PERFORMANCE IMPROVEMENT OF A 330 MWe POWER PLANT BY FLUE GAS HEAT RECOVERY SYSTEM

In a utility boiler, the most heat loss is from the exhaust flue gas. In order to reduce the exhaust flue gas temperature and further boost the plant efficiency, an improved indirect flue gas heat recovery system and an additional economizer system are proposed. The waste heat of flue gas is used for high-pressure condensate regeneration heating. This reduces high pressure steam extraction from steam turbine and more power is generated. The waste heat recovery of flue gas decreases coal consumption. Other approaches for heat recovery of flue gas, direct utilization of flue gas energy and indirect flue gas heat recovery system, are also considered in this work. The proposed systems coupled with a reference 330 MWe power plant are simulated using equivalent enthalpy drop method. The results show that the additional economizer scheme has the best performance. When the exhaust flue gas temperature decreases from 153 degrees C to 123 degrees C, power output increases by 6.37 MWe and increment in plant efficiency is about 1.89%. For the improved indirectflue gas heat recovery system, power output increases by 5.68 MWe and the increment in plant efficiency is 1.69%.