Nitrogen oxides are one of the main sources of air pollution.They directly endanger human health, but also cause very serious harm to the environment.To be specific, the following points are made:
(1) toxic effects on human body.
(2) one of the main causes of acid rain and acid fog.
(3) when nitrogen oxides and volatile organic compounds in the atmosphere reach a certain concentration, a series of photochemical reactions will be generated under sunlight, forming photochemical smog.
(4) participating in ozone layer destruction activities.
(5) destroy plants.
There are several main ways to produce nitrogen oxide in the calcining process of cement clinker: first, thermal nitrogen oxide, which is produced when the cement kiln head fuel is burned at 1400℃ or above;The second is instantaneous nitrogen oxides, which are formed in the front of the flame in the presence of hydrocarbon free radicals.The third fuel, the chemical mixture contained in the fuel.Nitrogen is produced.Theoretical analysis and practical experience show that the proportion of nitrogen oxide in rotary kiln head is large.Most (NOX) emissions belong to the first batch of hot NOX, and the emissions of many domestic production lines do not meet the national standards (gb4915-2004 stipulated that the nitrogen oxide (NOX) emissions of cement manufacturing should be less than 800mg/m3, about 650ppm).Nitrogen oxides from combustion can be reduced by improving combustion techniques.The main methods are as follows:
1. Select fuel with low nitrogen content, including fuel denitrification and conversion to low nitrogen fuel;
2. Reduce the excess air coefficient and oxygen concentration around the fuel;
3. Lower the temperature with less excess air.The peak decreases the NO x of the thermal reaction;
4. Increase the residence time of combustible in flame front peak and reaction zone at lower oxygen concentration.
Burner is an important equipment to ensure stable combustion and full combustion of fuel in cement industry.Therefore, in order to inhibit nox production, it is necessary to start with the burner.Considering the characteristics of cement rotary kiln, the temperature and stable oxidation atmosphere needed for clinker calcining must be guaranteed.Therefore, the second and fourth methods mentioned above are the main ways to inhibit the formation of nitrogen oxides.The traditional cement kiln burner is composed of external air duct, internal air duct, coal duct, central air duct, oil gun barrel, cyclone separator and flame stabilizer.The outer air duct is set on the inner air duct, the inner air duct is telescopic and sliding on the coal air duct, the coal air duct is set on the central air duct, the central air duct is set on the oil gun barrel, the cyclone separator is set between the inner air duct and the coal air duct, and the flame stabilizer is installed on the inner air duct.Computed tomography.Between the central duct and the barrel.The outlet of the channel is independent and the area of the channel is fixed.Although the coal duct can also expand and move in the internal duct, the sectional area of the outlet is fixed.In order to regulate the wind speed at the outlet of the duct, only through the duct.By adjusting the air volume of each channel, if you want to increase the wind speed, you need to increase the air volume.At the same time, we need to adjust the air inside and outside to not only increase energy consumption, but also provide enough oxygen to increase the production of nitrogen oxides.Therefore, high nitrogen oxide (NO x) has obvious serious defects.
The burner developed by our company overcomes the shortcomings of existing cement kilns.It can effectively increase the residence time of combustible in the flame front peak and reaction zone, and has the effect of inhibiting NOx. It belongs to cement clinker calcining equipment.
