The reasons of cold air mixed into the pulverizing system was analyzed, the varying quantity of cold air mixed into the pulverizing system and the increasing quantity of flue gas temperature were introduced, the new technology of hot primary air heater for preventing the cold air mixing into the system was recommended, and the function, benefit and limitation of the heater were introduced. The main conclusions were that one of important reasons that caused the increase of flue gas temperature is the cold air mixed into the pulverizing system. The application of the hot primary air heater can reduce the quantity of cold air mixed into the system largely, even eliminate, which largely reduce the temperature of fine gas. Meanwhile, by adjusting the quantity of condensing water of the hot primary air heater, the temperature of flue gas can be adjust within 20 ℃, which partly replaced beth the heater and the system of hot air recirculation, and shortened the time of putting into operation. This function is unique in the measures for reducing temperature of flue gas.%简要分析了大容量高参数锅炉制粉系统掺入大量冷风的原因,并简述了其冷风掺入量的变化范围及引起的锅炉排烟温度升高幅度,重点推荐一种旨在消除制粉系统掺入冷风的新技术,即热一次风加热器;并分析了其作用、优势及局限.分析认为:制粉系统掺入冷风是造成大容量锅炉排烟温度高的重要原因之一,应用热一次风加热器技术可大幅度减少制粉掺入的冷风量,甚至将其减小到0,进而有效地降低锅炉排烟温度;同时,热一次风加热器技术可通过其冷却介质流量的调节,在20℃的范围内调节锅炉排烟温度,部分起到暖风器或热风再循环系统的作用,减少后者的投运时间,在各种降低排烟温度的措施中,这一作用是热一次风加热器所独有的.
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