In order to prevent severe damage to boiler and steam turbine, on condition of ensuring personal safety, in case of the following circumstances happen. the boiler shall be emergency stopped.
1. MFT doesn’t act, when the boiler shall be protected by MFT acting.
2. Serious overflow occurs in boiler water, the boiler water level reaches to + 200 mm, but the boiler MFT refuses to act.
3.  The boiler water is in server shortage, the water level reaches to - 280 - mm, but the boiler MFT refuses to act.
4. The boiler tube bursts , and is unable to maintain a normal water level in the steam drum;
5. The external pipes of water wall, superheater, reheater and economizer burst, which endanger personal safety and equipment safety or operation.
6.  The chamber or tail-end flue explodes,  damaging the equipment, and there is a risk of collapse or boiler steel frame are burned red.
7. The tail flue combustions again, and the exhaust flame temperature reaches above 250 ℃.
8. When all the water level gauges are damaged, and the steam drum water level cannot monitored.
9. The steam pressure is exceeding the security value, and the boiler safety valve doesn't act,  and at the same time one or two by-pass and bleeding valve cannot be opened.
10. When all the operator stations of the thermal control DCS system  (all PCs "black screen" or "crash") have failure and the reliable operating and monitoring means are not available.
11. The control power supply is completely interrupted, and it can't be resumed immediately, and the monitoring and controlling cannot be done.
12. The reheating steam of boiler is interrupted.
13. The plant building fires, which directly  threat to the safe operation of boiler. （lsh）