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Low-nitrogen burners are excellent combustion devices that utilize low-nitrogen combustion technology to control the emission of nitrogen oxides (NOx), reduce their formation, and thus achieve energy conservation and environmental protection. During the operation of the burner, many structures and related parameters come into play; during this time, it is necessary to ensure that all operational parameters are optimized in order to reduce NOx emissions. Next, the editor will share with you the operating parameters of low-nitrogen burners that affect NOx generation. I. Influence of air preheating temperature At present, in order to improve the combustion efficiency of heating furnaces and reduce the amount of heat required to warm cold air inside the furnace, most burner systems require air to be preheated. Although air preheating improves the efficiency of heating furnaces and also aids in ignition for certain fuels, it raises the flame temperature, which affects NO control. Emissions have no positive effect. Related studies indicate that NOx emission concentrations increase as the air preheating temperature rises. After the air is preheated, the energy required to preheat cold air is reduced under the same power output, thereby increasing the temperature of the premixed flame; as a result, the NOx emission concentration increases. If full premixed combustion is used, the overall NOx emission concentration is low. II. Influence of fuel and air premixing degree At present, most large-scale burners use non-premixed combustion; that is, the fuel gas and air do not mix within the burner, but rather the two streams mix with each other at the burner outlet through different jets, swirls, etc., thereby enabling ignition and combustion. This combustion rate depends on the mixing rate of air and fuel gas, and is known as diffusion-controlled combustion. The combustion method in which gas and air are mixed in the burner in advance and then ignited at the outlet is called premixed combustion. The combustion rate of premixed combustion depends on the kinetic reaction rate of the fuel itself, which is why it is referred to as kinetically controlled combustion. The two combustion methods have their respective advantages and disadvantages, and the degree of mixing between fuel and air also has a significant impact on NOx formation. As the premixing degree increases, the concentration of fast-type NOx decreases, while the concentration of thermal-type NOx increases. Therefore, it can be considered that within the pre-mixing ratio range of 30% to 70%, the formation of rapid-type NOx and that of thermal-type NOx act together. Since these two processes have an inverse relationship as the pre-mixing ratio changes, the amount of NOx generated remains relatively constant within this range. However, once the pre-mixing ratio exceeds 70%, the conditions for the formation of rapid-type NOx are weakened, and the formation of thermal-type NOx gradually takes precedence. III. Influence of the gas/air velocity ratio In non-premixed burners, gas and air are ejected from nozzles separately and then mixed in a certain manner. Therefore, the velocity ratio of gas to air has a significant impact on the mixing effect, as well as on the rate of the combustion reaction. As the gas/air injection velocity ratio increases, the peak flame temperature rises slightly, but the temperature distribution within the furnace becomes more uniform, and NOx emissions decrease as well. IV. Impact of flue gas recirculation rate Flue gas recirculation involves drawing a portion of the low-temperature flue gas before the air preheater in the heating furnace and sending it directly into the furnace, or mixing it with primary or secondary air before sending it into the furnace. This not only reduces the combustion temperature but also lowers the oxygen concentration, thereby reducing the emission levels of NOx. Flue gas with a lower temperature is drawn from in front of the air preheater, and this drawn flue gas is sent to the air-flue gas mixer via a recirculation fan. After mixing with air, it is then fed into the furnace. The ratio of the amount of flue gas that is recirculated to the amount of flue gas that would be used without recirculation is known as the flue gas recirculation rate. Experience shows that when the flue gas recirculation rate is 15%–20%, the NOx emission concentration in coal-fired boilers can be reduced by about 25%. The reduction rate of NOx increases as the flue gas recirculation rate rises, and it is also related to the type of fuel and the combustion temperature; the higher the combustion temperature, the greater the impact of flue gas recirculation on the NOx reduction rate.