Numerical Analysis of Nox Production under the Air Staged Combustion

The formation of thermal NO and fuel type NO emission under the air staged combustion in a tower pulverized coal fired boiler that burners are arranged in the front and the rear wall are investigated in this paper. Effects of the distribution of oxygen in the main combustion zone on NOx are then analyze qualitatively. The results show that when the SOFA ratio is 34.98%, NOx yield is at the minimum; thermal NO is not only related to temperature, but also by the influence of oxygen distribution. When oxygen is more and the temperature is high, it is conducive to the formation of thermal NO. The formation of fuel NO and the amount of oxygen and CO have a positive correlation, and more oxygen is conducive to the formation of thermal NO. When CO is more, indicating that the reducibility is good, it will result in significant reduction of fuel NO. Based on the control of the mount of SOFA, the distribution of oxygen in the main combustion zone must be on the rational allocation; in the case of normal combustion, the input of air could not be too much through the first layer burners.