The Study On Deeply Cooling Down The Boiler Flue Gas In Power Plant

This thesis studied the relationship between boiler exit flue gas temperature and the efficiency of boiler and electrostatic precipitator. The conclusion is given that the boiler exit flue gas temperature by deeply cooled down to 100~110℃ will greatly saving energy and improve the entironment. Taking into consideration of the problem of the boiler in HuangDao Power Plant, such as much higher value of boiler exit flue gas temperature , three retrofit plans are proposed. Through the plan Ⅲ,which add a flue gas heat exchanger in the boiler tail flue ,it is possible that the boiler exit flue gas temperature deeply reduced to 100~110℃.The results of the calculation and analysis of the economical benefit and the emission of fly ash and exhaust gas under different flue gas temperature indicate that for coal-fired power plant the boiler exit flue gas temperature deeply cooled can make great economic benefit and environment benefit. It's a feasible way to relax the international and domestic pressure which require to reduce the emission of exhaust gas.By analysing the heat absorption of the tube-type air preheater of the boiler in HuangDao Power Plant, the low heat transfer rate is found. The air flow distribution along the tube bank of the tube-type air preheater is calculated by numerical method. The retrofit plan for the tube-type air preheater is proposed and, through the numerical simulation of the effect of tube arrangement on the airflow distribution ,the retrofit plan is shown to be of feasibility. During the modification of tail section heating surface, kinds of technology such as intensified heat-transfer and flue gas heat exchanger system are applied. The questions how to choice the parameters and how to achieve the most economic benefit for the flue gas heat exchanger system are discussed. The results indicate that the system possess many excellency such as simple structure ,great benefit and quick giveback time etc. But the complexity of the flue gas heat exchanger system make the study is not very perfect and needs further research.This paper generally discussed the economical and environmental benefit by deeply cooled down the exit flue gas temperature ant will be helpful to the cause of energy saving and environmental protection in coal-fired power plant.