The chemical principle and development direction of ultra-low nitrogen burners
Writer： admin Time：2021-11-09 16:26 Browse：℃
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The amount of thermal NOx generated by the ultra-low nitrogen burner is proportional to the square root of the oxygen concentration, and the oxygen content is also an important indicator that affects the amount of thermal NOx generated. As the O2 concentration increases and the air preheating temperature increases, the amount of NOx generated increases, but it will reach a high value. When the oxygen concentration is too high, the excess oxygen will have a cooling effect on the flame. When air is used, the O2 content increases, the excess air ratio increases, and more N2 is absorbed, thereby reducing the flame temperature. As the temperature decreases, the amount of NOx produced decreases.
The reaction time of the ultra-low nitrogen burner is also an important indicator. The heat generation process of NOx is very slow. In the high temperature region, the reaction time has a linear relationship with the amount of NOx produced. In the design of the kiln, minimize the residence time of the fuel and medium in the high temperature area, especially the high temperature area with high oxygen content, which can effectively reduce the generation of hot nitrogen oxides. When the kiln is formed, a local oxygen-deficient or oxygen-deficient environment is formed in the high temperature area, and the increase of oxygen in the low temperature area can effectively reduce the generation of thermal NOx under the conditions of ensuring full combustion.
1.3 Fuel-based NOX: It is produced by the reaction of N in the fuel. In a system that uses coal as the main fuel, fuel-based NOX accounts for more than 60%. Fuel-based nitrogen oxides are mainly formed in the initial stage of fuel combustion, and are mainly intermediate products N, CN, HCN, etc. produced by the pyrolysis of nitrogen-containing organic compounds to generate nitrogen oxides. NOX fuel is easier to produce than heat. The nitrogen content of coal is about 0.5-2.5%.
When the coal in the ultra-low nitrogen burner is pyrolyzed to remove volatiles, part of the N in the coal volatiles will precipitate out together with volatiles in the form of amines (RNH, NH3) and cyanide (RCN, HCN) . The proportion of nitrogen in coal varies with coal type and pyrolysis temperature. The main compounds are HCN and NH3.
Under the high temperature of 1800K, the ratio of volatile N to NO in coal is usually about 10% for ultra-low nitrogen burners. When HCN encounters oxygen, it will generate NCO and continue to oxidize to generate NO. If it returns, NH is generated, and then N2 is generated.
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The above is an introduction to the chemical principles and development direction of ultra-low nitrogen burners for you. If you want to know other content of low-nitrogen burners, please pay attention to Zhengzhou Bona Thermal Energy Equipment Co., Ltd.