How to solve the problem of coking in circulating fluidized bed boiler operation?

(Question Details) Specific Performance:

(1) The bed temperature has risen sharply.

(2) The oxygen level drops even to zero.

(3) The current of the primary blower is reduced, and the wind pressure in the wind chamber is high and fluctuates.

(4) The furnace negative pressure increases and the induced draft fan current decreases.

(5) Difficulties in slagging.

(6) If coking in low temperature, the bed temperature, bed pressure distribution is uneven, the deviation is too large, the bed pressure, the plenum pressure, the bed temperature is not normal, and the local bed temperature measurement point is not normally raised or lowered.

(7) The bed pressure indicator value fluctuates little.

Answer: causes of failure :

(1) Improper operation, resulting in overheated bed temperature and coking.

(2) The primary air volume during operation is kept too small, which is lower than the minimum fluidized air volume, so that the material can’t be well fluidized but piled up, the temperature field of the entire furnace is changed, the burning share of the suspension stage is decreased, and the boiler output is reduced, if increase the amount of coal blindly at this time, it will inevitably cause overheating and coking.

(3) Bad fluidization caused by damaged hood.

(4) Recycling device blocking the ash and causing cycle interruption.

(5) The material pressure difference is too high.

Troubleshooting:

(1) Strengthen the combustion adjustment and increase the fluidization speed. If the material pressure difference is too high, the slag should be strengthened.

(2) If the bed temperature is too high, the coal supply will be reduced to zero,open the door with high negative pressure of the furnace, and remove the focal block with a hook.

(3) If the coking of furnace is serious, we should stop the operation of boiler.