Abstract:

This paper aimed to solve the problems of overheating of heating surface, large deviation of water wall temperature, smoke temperature and steam temperature caused by unbalanced combustion in the operation of large coal-fired boilers. First, the causes of boiler thermal deviation and its harm to boiler operation safety were analyzed, and then the general idea of boiler thermal deviation prevention was proposed based on primary air and pulverized coal online balance control system, wall temperature and steam temperature deviation, and adjusting secondary air volume distribution. Finally, the boiler thermal deviation automatic control system was designed and applied to a 1 000 MW opposed firing boiler in a domestic power plant and other boilers to verify the practicability and effectiveness of the system. The results show that the system can make the air coal ratio of each burner balanced and consistent, realize the accurate measurement and control of the burner state, eliminate the combustion deviation and local combustion deterioration of the burner, and improve the hidden danger of boiler safe operation caused by combustion thermal deviation.

Key words: coal-fired boiler, thermal deviation, prevention and control program, one wind pulverized coal, secondary air volume