Accident Handling 35: What are the hazards caused by failures in the positive-pressure ash removal system of circulating fluidized bed boilers?
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What are the hazards caused by failures in the positive-pressure ash removal system of circulating fluidized bed boilers?
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 positive-pressure ash removal system of such a boiler fails or the sealing is inadequate, ash and air will leak out, which not only affects the working environment but also severely impacts the boiler’s economic operation 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 inevitably leads to a decrease in the boiler’s load-carrying capacity.
Failures in the silo pump ash conveying system can lead to: 1. Severe ash accumulation in the silo pump, which eventually causes blockages such that the ash hopper fills up and covers the filter bags or even damages them. 2. It causes an increase in the differential pressure of the dust collector, as well as a decrease in negative pressure or an increase in positive pressure inside the furnace. 3. This leads to an increase in the amount of fly ash entering the induced draft fan, resulting in wear on the fan’s impeller.