Low nitrogen burner refers to the burner with low NOx emission in the process of fuel combustion. The NOx emission of traditional natural gas boiler burner is generally 120 ~ 150mg / m ³ about. The NOx emission of low nitrogen burner is generally 30 ~ 80mg / m ³ Left and right. NOx emission is 30mg / m ³ The following are generally referred to as ultra-low nitrogen burners. At present, low nitrogen burners can be roughly divided into the following categories according to the principle: the stage burner planned according to the principle of staged combustion makes the fuel and air burn in sections. Because the combustion violates the theoretical equivalence ratio, the generation of nitrogen can be reduced.

   The low nitrogen burner uses the pressure head of combustion supporting air to suck back part of the combustion flue gas, enter the burner and burn with air. Because of flue gas recirculation, the heat capacity of combustion flue gas is large, the combustion temperature decreases and NOx is reduced. Another self recirculation burner is to recycle part of the flue gas directly in the burner and participate in the combustion process. This burner has the dual effects of restraining nitrogen oxide and saving energy. The principle is to make part of the fuel burn too rich and the other part burn too light, but the air volume on the whole remains unchanged. Because both parts burn against the chemical equivalence ratio, NOx is very low. This kind of combustion is also called contrary combustion or non chemical equivalent combustion.

   The principle of low nitrogen burner is to divide one flame into several small flames. Because the small flame has large heat dissipation area and low flame temperature, the "thermal reaction no" is reduced. In addition, the small flame shortens the residence time of oxygen, nitrogen and other gases in the flame, and has a significant restraint effect on "thermal reaction no" and "fuel no". The residence time of flue gas in the high temperature zone is one of the main factors affecting the generation of NOx. Improving the mixing of combustion and air can reduce the thickness of the flame surface. Under the condition of constant combustion load, the residence time of flue gas in the flame surface, i.e. high temperature zone, is shortened, so the generation of NOx is reduced. The mixed promotion burner is planned according to this principle.

   The precombustion chamber of low nitrogen burner is a low nitrogen 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 mixed to form a fuel rich mixture in the primary combustion area of the precombustion chamber. Because of lack of oxygen, only part of the fuel is burned, and the fuel precipitates vapor in the primary flame area with poor oxygen and low flame temperature, so the generation of NOx is reduced. The essence of any low nitrogen combustion technology is to promote combustion Technology for process control. According to the 20-year operation experience of low nitrogen burners in Europe and America, in order to end the real and reliable low nitrogen combustion of industrial boilers, it is not enough to replace or transform the burners. It is also necessary to upgrade the combustion control equipment, such as adding "timely control" combustion control equipment.