An annealing furnace in the solid solution stainless steel pickling and annealing line of a well-known domestic company in Guangxi is equipped with 120 low NOx air-staged burners, SNLNOx. This annealing furnace has 8 temperature control zones, which adopt a double-cross limit flow control method.

The furnace temperature ranges from 1150 to 1200°C, and the air preheating temperature can reach up to 600°C. When producing, the air preheating temperature at the entrance of the burner farthest from the heat exchanger is above 450°C.

The components of flue gas in each zone during normal production are as follows:

The NOx emissions of 8 zones and the NOx emissions of total exhaust pipe at different times are as follows(ref. 8% O2):

Raising the air preheating temperature and strengthening waste heat recovery are the main methods to save energy in industrial furnaces. The air preheating temperature of this annealing furnace can reach up to 600°C, and low NOx emissions can still be achieved, which truly meets the requirements of energy saving and environmental protection.