Study on model of ash fouling monitoring in rotary air preheater of coal-fired power plant boiler

As an important equipment to preheat air and to improve coal-fired power plant boiler efficiency with the heat of boiler tail flue gas, the air preheater's safe and economic operation influences unit efficiency directly. At present, above 80% utility-type unit in domestic uses tri-sectional rotary air preheater. Therefore, the rotary air preheater has become an indispensable auxiliary machinery in modern large boilers. Firstly, a kind of air preheater heat transfer model of inverse flue gas flow is proposed in this paper, the ash fouling situation of air preheater is showed with the cleanliness factors based on heat transfer model and flue gas pressure drop model respectively. Moreover, the cleanliness factor of air preheater is calculated and gained through thermodynamics indirectly with energy balance method. According to the verification results of the actual operation data of a 600MW coal-fired unit, both of these two kinds of mode can reflect the dynamic change of ash fouling situation of air preheater in real time, and among which, the cleanliness factor based on flue gas pressure drop mode has a better online monitoring result on ash fouling situation of heat transfer surface.