Research On Terminal Temperature Difference Property Of High-pressure Heater Under Abnormal Operating Conditions

High pressure heater,which use extraction steam in steam turbine to heat feed water in boiler, is an important auxiliary equipment in power plant, the operating performance directly affect thermal economy of the entire unit. Variable conditions, fouling, leakage, pipe blocking, non-condensable gas and water level are main factors that affect operation performance of high pressure heater, so studying these factors is important in heat recovery system designing, energy saving, thermal equipment improving, and the operating level enhancing.On the basis of heat tansferring theory and heat exchanging characteristics analysis of three sections of horizontal high pressure heater, a new calculation model which only considered the operating parameters in heater side was established in this paper by referring the HEI standerd of USA and Bemelmans formula correction model of All-Union Research Institute, the verifiying results showed that this mathematical model is simple, precise and quick when calculating the operating parameters in heater side. Taking high pressure heater of the300MW and660MW unit in Southern nets in Hebei as the research object, optimization measures was proposed by analyzing the affection of scaling, leakage, plugging, non-condensing gas gathering to heater-side and calculating the impact of the various factors. From the angle of heat transferring and balance, calculation model of heater-side was established when taking the high and low water level into consideration, a new optimizing method was proposed based on the water level adjusting test to provide theorical proof to determine the appropriote water level for high pressure heater.