What is denitrification? The so-called denitrification refers to the removal of NOx from flue gas, which is mainly composed of NO and NO2, with NO content accounting for more than 90%. To remove NO and NO2 from flue gas, it is necessary to study the properties of NO and NO2. NO is a lazy oxide that, although soluble in water, cannot generate nitrogen as an oxygen-containing acid. At 0 ℃, one volume of water can dissolve 0.07 volumes of NO. The most unique chemical property of NO is its additive effect, which can react with oxidants in the air at room temperature to produce reddish brown NO2. NO is unstable and when it meets O2, it can cause O2 to split into oxygen atoms, which then combine with one of the oxygen atoms to form NO2. NO2 is a reddish brown gas with a particularly unpleasant odor, which aggregates into N2O4 at around -10 ℃. At 120 ℃, N2O4 decomposes completely into NO2, and at higher temperatures, NO2 begins to decompose into NO and O2; NO2 dissolves in water to form nitric acid and nitrous acid; Nitrite reacts with desulfurization NH3 to form ammonium nitrate, which is more soluble in water. The toxicity of NO2 is five times that of NO. How do NO and NO2 occur? In general, N2 and O2 do not undergo chemical reactions. Nitrogen oxides occur during discharge in air or high-temperature incineration, primarily producing NO, which is then oxidized to NO2. During high-temperature incineration, substances such as nitrogen in the air and nitrogen compounds that cannot be incinerated react chemically with oxygen, primarily forming NO. Subsequently, a portion of it combines with oxidation in the flue to form NO2. Most of the NO is discharged into the atmosphere from the chimney and combines with oxygen in the atmosphere to form NO2. And NO, which has not been oxidized to NO2, coexists with NO2 in the atmosphere. The higher the temperature of the incinerated gas during the incineration process, the more excess air there is, resulting in a higher amount of NO. The higher the incineration power, the easier it is to generate NO. More than 90% of the NO2 generated by this incineration method is NO, with less NO2. According to commonly used incineration methods, the content of NO2 in coal incineration materials is 500-1500ppm.

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