Low nitrogen burner principle (latest version)

Low nitrogen burner principle (latest version)

Low nitrogen burner principle (latest version)
Low nitrogen oxide burners and low nitrogen oxide burners refer to burners with low nitrogen oxide emissions during fuel combustion. The use of low nitrogen oxide burners can reduce nitrogen oxide emissions during the combustion process.
The nitrogen oxides generated during the combustion process are mainly NO and NO2, commonly referred to as NOx. A large number of experimental results indicate that the nitrogen oxide emissions from combustion devices are mainly composed of NO, accounting for an average of 95%, while NO2 only accounts for 5%.
The NO generated by general fuel combustion mainly comes from two aspects: firstly, the oxidation of nitrogen (combustion supporting air) in the combustion air; The second is the thermal decomposition and reoxidation of nitrides during the combustion process. In most combustion devices, the former is the main source of NO, which we refer to as' thermal reaction NO ', while the latter is referred to as' fuel NO' and 'immediate NO'.
The NO formed during the combustion process can react with intermediates containing nitrogen atoms, reducing NO to NO2. In fact, in addition to these reactions, NO can also form NO2 with various nitrogen-containing compounds. When the reaction reaches chemical equilibrium in the actual combustion device, the ratio of [NO2]/[NO] is very small, that is, the conversion of NO to NO2 is very small and can be ignored.
Nitrogen oxide reduction combustion technology
NOx is generated through combustion, and combustion methods and conditions have a significant impact on the production of NOx. Therefore, NOx can be reduced by improving combustion technology. The main methods are as follows:
Choose fuels with low nitrogen content, including denitrification and conversion to low nitrogen fuels;
Reduce the excess coefficient of air and reduce the oxygen concentration around the fuel;
Reduce the peak temperature and reduce the 'thermal reaction NO' when there is less excess air;
At low oxygen concentrations, the duration of the fuel in the flame front peak and reaction zone increases.
The commonly used specific methods to reduce NOx formation and emissions include staged combustion, reburning, low oxygen combustion, shadow bias combustion, and flue gas recirculation.
Introduction to General Applications of Low Nitrogen Oxide Burners
The burner is an important equipment in industrial furnaces, which ensures stable ignition and complete combustion of fuel and other processes. Therefore, suppressing the generation of NOx must start from the burner. According to NOx reduction combustion technology, low NOx burners can be roughly divided into the following categories:
1. Stage burner
This stage of burner is designed based on the principle of staged combustion, which mixes fuel and air for combustion. Due to the deviation of combustion from the theoretical equivalence ratio, the generation of NOx can be reduced.
2. Self circulating burner
One method is to use the combustion air pressure head to suck some smoke back into the burner and mix it with air for combustion. Due to flue gas recirculation, the thermal capacity of combustion flue gas is large, the combustion temperature is high, and NOx is reduced.
Another type of self circulating burner is to directly recover some flue gas into the burner and add it to the combustion process. This burner has a dual function of inhibiting nitrogen oxides and saving energy.
3. Sunshade burner
The principle is to cause some fuels to burn too strongly and some fuels to burn too lightly, but the total amount of air above them remains unchanged. Due to the skewed adsorption ratio of both parts, NOx is very low, which is also known as deflection combustion or non inert combustion.
4. Split flame burner
The principle is to divide the flame into several small flames. Due to the large heat dissipation area of the small flame and the low flame temperature, the "thermal reaction NO" is reduced. In addition, the small flame reduces the residence time of gases such as oxygen and nitrogen in the flame, and has a significant inhibitory effect on both "thermal reaction NO" and "fuel NO".
5. Mixed Booster Burner
The residence time of flue gas in the high-temperature zone is one of the main factors affecting the production of NOx. Improving the mixing of combustion and air can make the thickness of the flame surface thinner. Under the same combustion load, the residence time of flue gas on the flame surface, i.e. in the high-temperature zone, is shortened, thereby reducing the production of NOx. The hybrid pressurized burner is designed based on this principle.
6. Low NOx precombustion chamber burner
The development of precombustion chambers in China in the past decade is an efficient and low NOx combustion technology. Generally speaking, it is a type of precombustion chamber with air or secondary air and fuel injection system that mixes fuel with air to form a mixture of fuel in the combustion zone. Due to oxygen deficiency, it is only a part of fuel combustion, and the fuel has areas of flame volatile precipitation under oxygen deficiency and low flame temperature, thereby reducing the formation of NOx.