Nitrogen oxides (NOX) are a general term for a class of nitrogen and oxygen compounds, mainly composed of nitric oxide (NO) and nitrogen dioxide (NO2), as well as nitrous oxide (N2O) and other forms. They are generated during high-temperature combustion and cause serious harm to the environment and human health. Nitrogen oxides not only irritate and damage the human respiratory system, causing diseases such as bronchitis and emphysema, but are also a key factor in the formation of photochemical smog and acid rain, which has a strong irritating effect on the eyes and can cause breathing difficulties. In addition, as a greenhouse gas, N2O has a greenhouse effect 200 to 300 times that of carbon dioxide, has a significant impact on global warming, and can destroy the ozone layer, increase the amount of ultraviolet radiation reaching the earth, and have an adverse effect on human life and the ecosystem.

At present, the more mainstream flue gas denitrification technologies on the market are as follows:

Selective catalytic reduction (SCR): It is a mature and widely used denitrification technology on the market. It uses ammonia or urea as a reducing agent to reduce NOx to nitrogen and water that are harmless to the atmosphere under the action of a catalyst. SCR technology has a high denitrification efficiency, but the investment and operating costs are also relatively high.

Selective non-catalytic reduction (SNCR): Compared with SCR, SNCR technology does not require a catalyst, but directly sprays a reducing agent (such as ammonia or urea solution) into the furnace, using high temperature to reduce NOx to nitrogen and water. SNCR technology has low investment and operating costs, but the denitrification efficiency is also relatively low, and it is suitable for small-capacity boilers.

SNCR+SCR hybrid technology: Combining the advantages of SNCR and SCR technologies, preliminary denitrification is performed through SNCR technology, and then SCR technology is used to further improve the denitrification efficiency.

Low-nitrogen combustion technology: Reduce the generation of NOx by optimizing the combustion process, such as through staged combustion or the use of low-nitrogen burners.

Ozone oxidation denitrification technology: Ozone is used to oxidize NOx into a form that is easily soluble in water, and then removed through a scrubber, with a denitrification efficiency of more than 90%.

Wet denitrification technology: including alkali absorption method, acid absorption method, complex absorption method, liquid phase absorption reduction method, microbial method, oxidation absorption method, etc., to achieve NOx removal through different chemical absorbents.

Activated carbon method multi-pollutant synergistic control technology: using activated carbon to adsorb pollutants such as SO2 and H2S in flue gas, and reducing NOx to nitrogen on the surface of activated carbon.

Biological flue gas denitrification technology: using microorganisms to degrade NOx, suitable for small and medium-scale flue gas denitrification.

Low-temperature plasma denitrification technology: as an emerging technology, it decomposes NOx by generating non-equilibrium plasma, with the characteristics of fast reaction speed and no secondary pollution.

Multieffect synergistic organic amine denitrification technology: using multi-effect organic amine as a denitrifier, it is suitable for solving problems such as large amount of ammonia or urea, low denitrification efficiency, and serious ammonia escape. It has high denitrification efficiency and low comprehensive cost.

Among them, the most mature and widely used denitrification technology in the current market is selective catalytic reduction (SCR) technology, and the denitrification catalyst is the core part of SCR technology, which determines the denitrification efficiency and economy of the SCR system. Its construction cost accounts for more than 20% of the cost of flue gas denitrification projects, and its operating cost accounts for more than 30%.

At present, the application of denitrification in the non-electric industry market includes steel, cement, coking, waste incineration, biomass power generation, glass furnaces and many other fields. The implementation is being vigorously promoted, and new denitrification technologies and new catalysts are constantly being updated.

Hebei Chengyu has long been focusing on SNCR, SCR and SNCR+SCR denitrification technologies, and has rich experience in spray gun positioning, fog field optimization, precise ammonia spraying, catalyst efficiency, reductant utilization, system energy-saving control, etc. Based on the principle of "energy saving and low consumption, cost reduction and efficiency improvement", it has achieved the goal of "ultra-low emissions, low cost and low investment" for many polluting enterprises.