What are the working classifications of low nitrogen burners

What are the working classifications of low nitrogen burners
Low nitrogen burner refers to a burner that emits low nitrogen oxides during fuel combustion. Traditional natural gas boiler burners typically emit NOx of approximately 120-150mg/m3. The typical NOx emissions of low nitrogen burners are around 30-80mg/m3. NOx emissions below 30mg/m3 are commonly referred to as low nitrogen burners. At present, low nitrogen burners can be roughly divided into the following categories according to their principles: staged burners designed based on the principle of staged combustion, which mix fuel and air in stages. Due to combustion deviation from the theoretical equivalence ratio, they can reduce the generation of nitrogen.
A low nitrogen burner is a type of burner that uses the pressure head of the combustion air to suck back a portion of the combustion flue gas, enter the burner, and mix with the air for combustion. Due to the recirculation of flue gas, the heat capacity of combustion flue gas is large, the combustion temperature decreases, and NOx decreases. Another type of self circulating burner is to recycle a portion of the flue gas directly into the burner and add it to the combustion process. Low nitrogen burners have a dual effect of suppressing nitrogen oxides and saving energy. The principle is to make one part of the fuel burn too rich and the other part burn too light, but the overall air volume remains unchanged. Due to the combustion of both parts deviating from the stoichiometric ratio, NOx is very low. This type of combustion is also known as biased combustion or non stoichiometric combustion.
The principle of a low nitrogen burner is to divide a flame into several small flames. Due to the large heat dissipation area of the small flame and the lower flame temperature, the "thermal reaction NO" is reduced. In addition, the small flame shortens the residence time of gases such as oxygen and nitrogen in the flame, and has a significant inhibitory effect on "thermal reaction NO" and "fuel NO". The residence time of flue gas in high-temperature areas 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 flue gas is in a high-temperature state on the flame surface. The residence time in this area has been shortened, thereby reducing the generation of NOx.
Low nitrogen burners are essentially a technology for controlling the combustion process. To achieve continuous and reliable low nitrogen combustion in industrial boilers, simply replacing or modifying the burner is not enough. It is also necessary to upgrade the combustion control device, such as adding "timely control" and "combustion control device".