Denitration | What is the reason for the formation of nitrogen oxides in boiler flue gas?

Release time:

2022-10-18

itrogen oxides are the general name of nitrogen oxides, which are the common main pollutants in the atmosphere. They are mainly caused by automobile exhaust, flue gas from thermal power plants, and industrial emissions or leakage of nitric acid, nitrogen fertilizer, gunpowder, etc. Nitrogen oxides are composed of nitrogen and oxygen, including a variety of compounds. Common nitrogen oxides include NO, NO2, N2O, N2O3, N2O4, N2O5, etc., but almost all nitrogen oxides generated during combustion are NO and NO2. The oxides of these two kinds of nitrogen are usually called NOx.

The generation of nitrogen oxides during incineration is that the nitrogen oxides generated during coal combustion are mainly nitric oxide and nitrogen dioxide, and their generation and emission are closely related to combustion mode, especially combustion temperature and air excess coefficient. There are three main ways of NOx generation: fuel type, thermal type and rapid type.

In boiler flue gas, there are two main reasons for the generation of nitrogen oxides. One is nitrogen and oxygen in the air, which react at high temperatures to produce nitrogen oxides. The other is that the fuel contains nitrogen, which reacts with oxygen during combustion to produce nitrogen oxides.

Nitrogen oxides in flue gas mainly come from the reaction of nitrogen and oxygen in air under high temperature to produce nitrogen oxides.

However, the reaction between nitrogen and oxygen at high temperature mainly depends on the combustion temperature and nitrogen oxygen concentration. The higher the temperature is, the greater the concentration is generated, and the more nitrogen oxides are generated. Generally, most boilers reduce the combustion temperature and oxygen in the high temperature area, so that the combustion reaction in the high temperature area is in an oxygen deficient state. The combustion is incomplete. The flue gas is sent to the low temperature area for secondary air distribution combustion, so that other substances can burn completely, so as to reduce the emission of nitrogen oxides.

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