NOx is produced by combustion, and combustion methods and conditions have a great influence on the production of NOx. Therefore, combustion technology can be improved in history to lower NOx. The main ways are as follows: A. select fuel with low N content, including denitrification of fuel and change to low nitrogen fuel; B. lower the air surplus coefficient, organize excessive combustion to lower the oxygen concentration around the fuel; C. In the case of less residual air, the peak temperature is lowered to reduce the "thermal reaction no"; D, in the case of low oxygen concentration, the time for the combustibles to subside in the front peak and reaction zone is increased. The detailed methods to reduce NOx emission are: staged combustion, reburning, low oxygen combustion, bias combustion and flue gas recycling. The burner is an important equipment of the home stove. It guarantees the steady combustion of fuel and the complete combustion of fuel. Therefore, to suppress the production of NOx, we must start from the burner. Low NOx burners can be divided into the following categories: 1. Staged burners are used to make decision-making for staged combustion of fuel and air. As the combustion deviates from the appearance equivalence ratio, NOx can be manufactured in low NOx. 2. One of the self recycling burners is to use the pressure head of combustion supporting air to suck the unilateral combustion flue gas back into the burner and assimilate with the air for combustion. Because of flue gas recycling, the heat capacity of combustion flue gas is large, combustion temperature is low and NOx is reduced. Another kind of self recycling burner is to recycle the unilateral flue gas in the burner and enter the combustion process. This kind of burner has the dual consequences of inhibiting nitrogen oxide and saving energy. 3. The principle of thick thin burner is to make one side of fuel burn too thick and the other side burn too thin, but the air volume combination is unchanged as a whole. Because both sides burn at the deviation of chemical equivalence ratio, NOx is very low. This kind of combustion is also called deviation combustion or non chemical equivalence combustion. 4. The principle of segmented flame burner is to divide a flame into several small flames. Because of the large heat dissipation area of the small flame and the low temperature of the flame, the "thermal reaction no" decreases. In addition, the flame reduces the settling time of oxygen, nitrogen and other gases in the flame, which has a significant inhibitory effect on "thermal reaction no" and "fuel no". 5. The settling time of the flue gas of assimilating generous burner in the high temperature area is one of the main factors affecting the NOx production. Improving the assimilation of combustion and air can roughly reduce the thickness of the flame surface. Under the condition of constant combustion load, the settling time of the flue gas in the flame surface, i.e. the high temperature area, is compressed, so that the NOx production is low. The assimilation generous burner is based on this kind of decision. 6. Low NOx precombustion chamber burner precombustion chamber is a high compliance and low NOx staged combustion technology developed and studied in China in recent 10 years. The precombustion chamber is generally composed of primary air (or secondary air) and fuel injection system. The fuel and primary air are rapidly assimilated, resulting in rich fuel assimilates in the primary combustion area of the precombustion chamber. Due to lack of oxygen, only one side fuel is used for combustion In the primary flame zone with poor oxygen and low flame temperature, volatiles are separated out, so the production of NOx is reduced.
——Author：ebico