What should we do when a CFB boiler encounters a cyclone separator breakdown?

(Details on the problem) Specific Performance:

J valve inlet static pressure fluctuations led to J valve back feed discontinuous, and bed pressure, bed temperature has a large fluctuation, in severe case, it destroys outer cycle, makes the tail of the heated area of ​​ash is serious, causing the tail flue to burn, damages air preheater.

Answer：cause of failure:

(1) The cyclone separator doesn’t return material properly. Cyclone separators affect the separation effect of the separator due to the higher ash level, so that a certain amount of unseparated ash enters the flue, causing serious dust accumulation in the air precipitator, causing static pressure fluctuations at the inlet of the separator.

(2) An excessively high circulation rate causes the ash circulatory volume of the separator to be excessive and exceeds the flow capacity of the separator.

(3) Sudden changes in combustion conditions disrupt the separator cycle.

(4) The fluidized air ratio is not appropriate, and the separator recycled material is not completely fluidized.

Troubleshooting:

(1) When it is found that the recycled material is abnormal, timely adjust the air volume of the cyclone separator and reduce the boiler load if necessary; when the tail flue dust accumulation is serious, strengthen the soot blowing (note that the furnace negative pressure is controlled), if necessary, put ash at the emergency ash outlet.

(2) Properly reduce the air for slag cooler, appropriately increase the proportion of secondary air volume, reduce the combustion air volume, ensure that the fuel and bed material in the furnace have enough residence time, that is, increase the time and quantity of internal circulation, reduce the material proportion of the cyclone separator.

(3) When the combustion conditions suddenly change and the cycle is destroyed, the boiler operating parameters should be adjusted in time to establish a new balance.

(4) Strengthen the experience summary of the separator air ratio, search the optimum parameters of each part of the separator, select the appropriate fluidized air volume and loose wind, it is recommended that when the air volume is set and the return material is normal, the air volume should not be changed arbitrarily.