Under the following circumstances, the boiler unit operation shall be immediately stopped.
--- If it is of serious water shortage, the drum water level still could not be seen even if the water is supplied.
--- If it is of serious overflow, the drum water level rose to be higher than the highest seen level, the water level still could not be seen after the emergency drainage.
--- The tube bursting of the heating surface, and the drum normal level could not be maintained.
--- The boiler is of serious coking.
--- All the water level meters of boiler are all destroyed; the drum water level could not be monitored.
--- The flue after the boiler exit is firing, and the smoke temperature rises abnormally.
--- There is rapture on the furnace wall and there is danger of collapse, it threatens the safety of persons or equipments.
--- The system rejects the load; the steam pressure exceeds the limit, the safety door refuse to move, the pressure relief as the air exhaust is not enough.
For emergency shutdown, the boiler change is fast, some measures must be taken to prevent the accident form being more serious or to avoid the secondary accidents.
--- Cut off the boiler fuel quickly and lower the load in time.
--- Note to adjust the feedwater and maintain the normal water level.
--- If there is serious leakage in the combustion chamber, the water supply to the boiler should be stopped, and the bed material should be removed quickly.
--- If there is leakage in the flue, the normal drum water level should be maintained.
--- The cooling process of the emergency shutdown is the same with the normal shutdown, but the time could be shortened.