Phenomenon: 

1. The boiler steam pressure decreases sharply. 

2. The steam flow rate increases. 

3. The water level of steam drum rises and then falls. 

4. The temperature of superheated steam decreases. 

5. The indication of voltmeter and ammeter fluctuates. 

6. The indication of electrical load gauge or heating load increases suddenly. 

7. The indication of steam flow meter suddenly increases.

 Causes: 

1. The load of power system suddenly increases. 

2. The  steam consumption of heat user decreases suddenly. 

3. The adjacent boiler is in failure. 

Treatment: 

1. According to the increasing of load, the combustion shall be properly strengthened in order to maintain the stability of bed temperature of boiling bed, when necessary, the automatic control of negative pressure of boiler chamber and combustion in boiler shall be changed from "automatic" to "manual". 

2. If the load of power system suddenly increases, then the high load shall be maintained within short time, after the system becomes normal, the normal operation can be recovered. 

3. If the steam consumption of heat user suddenly increases, then it shall be reported to the shift-chief operator, and then operator for the steam turbine shall be contacted to properly reduce the electric load, and to pay attention to the maintenance of normal steam pressure of boiler. 

4. If the electric load of the generator cannot be reduced, and the steam pressure continually to decrease, then it shall be reported to the shift-chief operator and the operator for the steam turbine to properly reduce the hot load in order to maintain the normal steam pressure of boiler. 

5. If the adjacent boiler is in failure, then the high load of the operating boiler can be maintained within short time, and the boilers with fault shall be disconnected from the main steam pipe to restore the normal operation of the operating unit. 

6. According to the changes of the outlet temperature of superheated steam, appropriately adjust the flow rate of the attemperation water. When necessary， the automatic control of main steam temperature shall be adjusted from "automatic" to "manual". 

7. According to the indication of steam drum water level gauge, steam flowmeter and water flowmeter,  maintain normal water level of steam drum; When necessary, the automatic control adjustment of water level of boiler drum is changed  from "automatic" to "manual". When the feedwater supply pressure is too low, the operator for the steam turbine can be contacted for recovering.