一、前言电站锅炉空气预热器前装设暖风器,是利用汽轮机低压抽汽来预热进锅炉空气预热器的空气,从而提高空气预热器冷端壁温,避开烟气露点,防止空气预热器腐蚀和堵灰,使机组安全运行。电厂运行的实践证明,这个方法是行之有效的。但是采用这种方法对热力系统的效率及经济性有何影响,还说法不一。有的认为采用这种方法就象机组的给水回热系统一样,能提高机组的经济性,有的则不这样认为。为了弄清这个问题,对国产200MW 中间再热机组在电子计算机上进行了多工况的热力计算,根据计算结果 I. Introduction Power plant boiler air preheater installed before the heater is the use of steam turbine low pressure extraction to preheat the air into the boiler air preheater, thereby increasing the air preheater cold end wall temperature, to avoid the dew point of flue gas , To prevent the air preheater corrosion and ash blocking, the unit safe operation. The practice of power plant operation proved that this method is effective. However, it is not clear how this approach affects the efficiency and economy of the thermal system. Some people think that using this method, just like the unit’s water supply and heat recovery system, can improve the economy of the unit, while others do not think so. In order to clarify this issue, the domestic 200MW reheat unit on the computer in the multi-case thermal calculation, according to the calculation results