Nitrogen oxides produced during combustion are mainly NO and NO2, which are commonly referred to as NOX. A large number of experimental results show that the nitrogen oxides emitted by the combustion device are mainly NO, accounting for about 95% on average, while NO2 accounts for only about 5%.

In general, the NO produced by fuel combustion mainly comes from two aspects: one is the oxidation of nitrogen in the air used for combustion (combustion-supporting air); the other is the thermal decomposition and reoxidation of nitrides in fuel during combustion. In most combustion devices, the former is the main source of NO. We call this kind of NO "thermal reaction NO", the latter is "fuel NO", and there is also "instantaneous NO".

The NO formed during combustion can react with intermediate products of nitrogen atoms to reduce NO to NO2. In fact, in addition to these reactions, NO can also form NO2 with various nitrogen 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.

Combustion Technology for Reducing NO_x

NOx is produced by combustion, and combustion methods and combustion conditions have a great influence on the formation of NOx. Therefore, it can be reduced by improving combustion technology. The main ways are as follows:

Select fuel with low N content, including fuel denitrification and conversion to low nitrogen fuel.

Reducing the excess air coefficient and organizing excessive combustion can reduce the oxygen concentration around the fuel.

In the case of less residual air, the peak temperature can be reduced to reduce the "thermal reaction NO";

In the case of low oxygen concentration, the residence time of combustibles in the Pre-Flame peak and reaction zone is increased.

The specific methods to reduce the formation and emission of NOx are classified combustion, reburning, low oxygen combustion, bias combustion and flue gas recirculation.

Brief Introduction of Common Low Nitrogen Oxide Burners

Burner is an important equipment of industrial furnace. It guarantees the process of stable ignition and complete combustion of fuel. Therefore, to suppress the production of NOx, it is necessary to start with burner. According to the combustion technology of reducing NO_x, low NO_x burners can be roughly divided into the following categories:

1. Stage burner

The stage burner designed according to the principle of staged combustion can make the fuel and air mixed in stages. Because the combustion deviates from the theoretical equivalent ratio, the formation of NOx can be reduced.

2. Self-Recycling Burner

One is to use the pressure head of combustion-supporting air to suck back part of the burning flue gas and enter the burner to mix with air for combustion. Because of the flue gas recirculation, the heat capacity of the combustion flue gas is large, the combustion temperature decreases, and the NO_x decreases.

Another kind of self-recycling burner is that part of the flue gas is directly recycled into the burner, and the combustion process is added. This burner has the dual effects of inhibiting nitrogen oxide and saving energy.

3. Dense-lean burner

The principle is to make some fuels burn excessively dense and others burn excessively light, but the air volume remains unchanged as a whole. Because both parts are burned at deviated chemical equivalence ratio, the NO x is very low. This combustion is also called deviated combustion or non-chemical equivalence combustion.

4. Split Flame Burner

The principle is to divide a flame into several small flames. Because of the large heat dissipation area and low flame temperature, the "thermal reaction NO" decreases. In addition, the small flame shortens the residence time of oxygen, nitrogen and other gases in the flame, and has obvious inhibitory effect on "thermal reaction NO" and "fuel NO".

5. Mixed Promotion 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 reduce the thickness of flame surface. Under the condition of constant combustion load, the residence time of flue gas in the high temperature zone is shortened, thus reducing the production of NOx. Mixed acceleration burner is designed according to this principle.

6. Low NOx Pre-combustor Burner

Pre-combustion chamber is a kind of high efficiency and low NOx combustion technology developed and studied in recent 10 years in China. Pre-combustion chamber is generally composed of primary air (or secondary air) and fuel injection system. Fuel and primary air mix rapidly to form a fuel-rich mixture in the primary combustion zone of the pre-combustion chamber. Due to lack of oxygen, only part of the fuel is burned, and the fuel is in the one with poor oxygen and low flame temperature. Volatile matter is precipitated in the sub-flame zone, which reduces the formation of NOx.

合同编号	使用单位	设备型号	所属行业
HS17008	辽宁天保化工有限公司	HS100-MR	硅藻土行业
HS17027	临江长葛远通实业有限公司	HS700-TR	硅藻土行业
HS18002	内蒙富成矿业有限公司	HS300-TR	治炼行业
HS14011	东海特钢	HS100-GR	钢铁行业
HS18009	蓸妃甸市京滦水泥有限责任公司	HS750-TR	水泥行业
HS18010	唐山市永兴环保锅炉有限公司	HS120-GR	锅炉
HS18011	府谷远大活性炭有限公司	HS1000-GR	活性炭