1) Due to the rotation of the rotor, it inevitably introduces air from the grid silo into the flue gas, resulting in carryover air leakage.
2) Due to the rotation of the rotor, there is inevitably a gap between the stationary and moving parts. On the flue gas side, there is negative pressure, while on the air side, there is positive pressure. Consequently, the pressure difference causes air to leak towards the negative pressure side of the flue gas, resulting in direct air leakage.
The Air Preheater Leak Control System (LCS) has been malfunctioning, failing to automatically track the mushroom-shaped deformation of the hot-end fan-shaped seal plate to reduce the air leakage gap. Moreover, the presence of dusty air leaking towards the flue gas side has led to severe wear on the fan-shaped seal plate, further increasing the air leakage gap. Since the air leakage volume is proportional to the area of the leakage zone, the air leakage of the air preheater has drastically increased.
Due to the low calorific value and high ash content of Guangwang's lean coal used in boilers, as well as the low-temperature corrosion of the economizer heat exchange elements, especially those in the low-temperature section, severe ash accumulation and clogging in the economizer heat exchange elements occur. After the flow channels are blocked, the resistance to flow increases, leading to a greater pressure difference between the air side and flue gas side. Since the amount of air leakage is proportional to the square root of the pressure difference, the clogging exacerbates the air leakage.
