Do you know about various low nitrogen oxide burners?

Do you know about various low nitrogen oxide burners?
According to the principle of reducing nitrogen, there are four types of low nitrogen burners at present: staged combustion low nitrogen burner, dense dilute low nitrogen burner, self circulation low nitrogen burner, and split Flamboyant low nitrogen burner.
Firstly, there is a stage combustion type low nitrogen burner, which mainly uses the over rich combustion method to reduce combustion temperature and oxygen concentration, achieving the goal of suppressing NOx. The fuel phase combustion type low NOx burner can reduce the production of NOx, mainly because it organizes the aerodynamic working conditions and the mixing of fuel and air. The vortex blades are installed at the outlet of the combustion chamber to achieve a certain level of vortex intensity. Inject fuel onto the inner surface of the vortex layer to evenly mix the fuel, primary air, and some secondary air, forming a fuel rich combustion zone; The unburned combustibles in the rich zone mix with high-speed external airflow to form a fuel combustion zone, and finally complete the combustion process. This combustion method is different from the two-stage combustion mentioned above. In the fuel rich zone, due to high-temperature flue gas recirculation, the flame temperature is low and the air is insufficient, which not only suppresses temperature type NOx but also reduces the production of fuel type NOx. As the entire flame is surrounded by external rotating airflow, the smoke and NO generated in the fuel rich zone will continue to burn out when passing through the fuel lamp zone. This type of burner can reduce NOx concentration by about 50%.
Then there is a lean rich low nitrogen burner. The principle of a lean rich low nitrogen burner is to cause some fuels to overcombustion, while the other fuels burn too lightly. Due to the large amount of air, the combustion temperature will inevitably decrease, thereby reducing temperature type NOx. This type of combustion can "deviate from combustion" or "non chemically equivalent combustion". The upper part of the thick and thin burner is an ultra-thin burner, and the lower part is an excessively rich burner. The air used by the two burners is evenly distributed, with fuel distributed between the upper 22% -40% and the lower 78% -60%. If the deviation ratio is too large, the soot and NO will increase. The bias combustion Y-shaped injector that achieves dense and mild combustion on the nozzle is called a self bias combustion fuel nozzle. This type of fuel nozzle can be arranged in two ways, namely, the large and small nozzles are arranged for communication, the upper part is a small nozzle, and the lower part is a large nozzle. The large nozzle achieves rich combustion, while the small nozzle is too light. Compared with general nozzles, NOx production can be reduced by 20% to 40%.
The principle of a self circulating low NOx combustion chamber is to use circulating flue gas to absorb heat and reduce the oxygen concentration of combustion oxidants to control NOx. This burner has a good effect on reducing temperature NOx.
When using fuel with high N content, it is usually used in conjunction with the two-stage combustion method. According to data, when the flue gas recirculation rate is 20%, the NOx suppression effect is good, and the NOx emission concentration can be lower than 80mg/kg.
Finally, let's talk about the split flame low nitrogen burner. The principle is to divide a large flame into several small flames. Due to the large heat dissipation surface of the small flame, the flame temperature decreases, reducing the NOx type temperature; In addition, the flame becomes smaller, shortening the residence time of gases such as nitrogen and oxygen in the flame, and having a significant inhibitory effect on temperature type NOx or fuel type NOx. Split type (split type) burner and mechanical atomization fuel injector. Near the nozzle, the flame collides with several rod-shaped objects and divides into several strands; The internal mixed steam atomizer uses several nozzles to generate several combustion flames. Experiments have shown that these two types of burners not only produce lower NOx, but also lower soot concentrations. The NOx emission concentration is also extremely low, with a mechanical atomization combustion rate of 35mg/kg and a steam atomization combustion rate of 42mg/kg.