What are the working classifications of low nitrogen burners

What are the working classifications of low nitrogen burners
Low nitrogen burner refers to the burner that emits low nitrogen oxides during fuel combustion. Conventional natural gas boiler burners usually discharge about 120~150mg/m3 of NOx. The NOx emission of low nitrogen burner is generally about 30~80mg/m3. NOx emission lower than 30mg/m3 is generally referred to as low nitrogen burner. At present, low nitrogen burners can be roughly divided into the following categories according to the principle: the staged burner designed according to the staged combustion principle mixes fuel and air in a staged manner, which can reduce the production of nitrogen because the combustion deviates from the theoretical equivalence ratio.
Low nitrogen burner is a burner that uses the pressure head of combustion air to suck back part of combustion flue gas, enter the burner, and burn with air. Due to flue gas recirculation, the heat capacity of combustion flue gas is large, the combustion temperature is reduced, and NOx is reduced. Another type of self circulation burner is to recycle some flue gas directly in the burner and add it to the combustion process. Low nitrogen burner has dual functions of restraining nitrogen oxides and saving energy. The principle is to make some fuel burn too thick and the other fuel burn too light, but the overall air volume remains unchanged. The NOx is very low because these two parts are burned when they deviate from the stoichiometric ratio. This combustion is also known as biased combustion or non stoichiometric combustion.
The principle of low nitrogen burner is to divide a flame into several small flames. As the small flame has a large heat dissipation area and a 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 inhibition effect on "thermal reaction NO" and "fuel NO". The residence time of flue gas in high temperature zone is one of the main factors affecting NOx generation. The thickness of flame surface can be reduced by improving the mixing of combustion and air. Under the condition of constant combustion load, the flue gas is at high temperature on the flame surface. The residence time in this area is shortened, thereby reducing the amount of NOx generated.
Low nitrogen burner is essentially a technology to control combustion process. In order to achieve continuous and reliable low nitrogen combustion in industrial boilers, it is not enough to replace or transform the burners. It is also necessary to upgrade the combustion control device, such as adding "timely control" and "combustion control device".