Incident Handling 27: What are the hazards caused by poor sealing in a circulating fluidized bed boiler?

Since the furnace of a circulating fluidized bed boiler operates under positive pressure, the pressure inside the furnace fluctuates, and there is a large amount of circulating ash. If the sealing of such a boiler is poor, ash and air will leak out, which not only affects the working environment but also significantly impacts the boiler’s economic efficiency and its capacity to handle loads. Excessive leakage of ash or air increases the system resistance, reduces the amount of material returned to the furnace, and consequently lowers the boiler’s load-carrying capacity. The main areas where ash or air leakage occurs are at the wall penetrations of the lower header of the membrane-type water wall surrounding the furnace chamber, various air ducts, the slag inlet pipe of the cold slag holder, the junction between the return air duct and the furnace chamber, the junction between the cyclone separator and the top of the furnace chamber, and various expansion joints.

1. In the positive pressure area, air and dust can easily leak outward, resulting in heat loss, increased fan power consumption, and environmental pollution. 2. The negative pressure area facilitates the leakage of ambient air, which lowers the flue gas temperature, affects heat transfer, increases the water content in the flue gas, and raises the power consumption of the exhaust fans.

Since the furnace of a circulating fluidized bed boiler operates under positive pressure, the pressure inside the furnace fluctuates, and there is a large amount of circulating ash. If the sealing of such a boiler is poor, ash and air will leak out, which not only affects the working environment but also significantly impacts the boiler’s economic efficiency and its capacity to handle loads. Excessive leakage of ash or air increases the system resistance, reduces the amount of material returned to the furnace, and consequently lowers the boiler’s load-carrying capacity. The main areas where ash or air leakage occurs are at the wall penetrations of the lower header of the membrane-type water wall surrounding the furnace chamber, various air ducts, the slag inlet pipe of the cold slag holder, the junction between the return air duct and the furnace chamber, the junction between the cyclone separator and the top of the furnace chamber, and various expansion joints.