Accident Handling 20: How to prevent clogging of the return conveyor in a circulating fluidized bed boiler?

(1) Appropriately increase the fluidization air pressure to ensure that the material in the returner remains in a good fluidized state at all times. However, it should be noted that the fluidization air pressure should not be too high. (2) The temperature of the return material should be controlled, with special attention required when burning coal with high ash content and low ash melting point. (3) In actual operation, the shedding of refractory materials in the return conveyor is a rather problematic issue in return conveyor accidents; it not only can cause blockages in the return conveyor but also easily leads to damage to its outer wall and partition. To solve this problem, it is necessary to address various aspects such as the construction of refractory materials, their baking, and routine maintenance during operation. (4) The stable operation of the fluidization fan must be ensured to prevent the disappearance of the fluidization air and blockages in the air nozzles. (5) Every effort should be made to create the optimal combustion environment within the furnace for the combustion of coal particles, in order to reduce the carbon content in the recycled material. (6) Take measures to clear the loose air ducts or open the corresponding relief valves according to the material level.

This post was last edited by han*chen on 2015-8-19 at 16:02. 1. The type of coal used and its particle size distribution should, as much as possible, correspond to those specified in the design. If the ash fusion point decreases due to a change in the type of coal, the operating temperature of the combustion chamber must be adjusted accordingly. When using gangue or anthracite, secondary air should be introduced as early as possible according to the ratio of primary to secondary air, in order to enhance combustion of the coal within the combustion chamber and reduce post-combustion in the return material system. The crushing equipment must also be adjusted promptly to ensure a proper ratio of coarse and fine particles. 2. During operation, the temperature of the high-temperature cyclone separator should be closely monitored. If the separator exceeds its temperature limit, the air-coal ratio should be adjusted to control the temperature in the combustion chamber; if this does not resolve the issue, the furnace should be shut down immediately to determine the cause. 3. Check whether the seal of the return material system is in good condition; address any air leaks promptly. 4. Check whether the return material system is unobstructed, and remove any foreign objects promptly. 5. Ensure an appropriate amount of return air flow; a clogged air cap, or the presence of dust or casting materials in the return air chamber can all lead to a decrease in the return air flow. Such issues must be resolved promptly once they are detected.

To prevent blockage of the returner in a circulating fluidized bed boiler, the following measures should be taken: (1) Appropriately increase the fluidization air pressure to ensure that the material inside the returner remains in a good fluidized state at all times. However, it should be noted that the fluidization air pressure should not be too high. (2) The temperature of the return material should be controlled, with special attention required when burning coal with high ash content and low ash melting point. (3) In actual operation, the shedding of refractory materials in the return conveyor is a rather problematic issue in return conveyor accidents; it not only can cause blockages in the return conveyor but also easily leads to damage to its outer wall and partition. To solve this problem, it is necessary to address various aspects such as the construction of refractory materials, their baking, and routine maintenance during operation. (4) The stable operation of the fluidization fan must be ensured to prevent the disappearance of the fluidization air and blockages in the air nozzles. (5) Every effort should be made to create the optimal combustion environment within the furnace for the combustion of coal particles, in order to reduce the carbon content in the recycled material. (6) Take measures to clear the loose air ducts or open the corresponding relief valves according to the material level.