Abstract: This paper analyzes the reasons for the over high NOx emissions in exhaust gas after low-NOx burner was used in the 100 kt/a CBL-III cracking furnace. In consideration of the design conditions, working principles and actual operation of the low-NOx burner, the air leakage of the furnace body was blocked. Through adjusting the fan speed and the throttle opening of bottom burner and side wall burner, the oxygen content of exhaust gas was controlled and the thermal field distribution of furnace was optimized to reduce the NOx production in exhaust gas. After the optimization, NOx emissions of cracking furnace during normal operation met the national emission requirements. The influence of oxygen content of exhaust gas on NOx and CO production was explored, and an optimal range of oxygen content was determined. The influence of furnace production load on NOx production was analyzed, and the direction of operation adjustment of cracking furnace was proposed after the load changed. An operation manual was developed for low-NOx burner to guide the routine operation of cracking furnace.

Key words: cracking furnace, low-NOx burner, NOx