Low nitrogen transformation | Differences between SCR denitrification technology and SNCR technology

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SNCR (Selective non-catalytic reduction) and SCR(Selective catalytic reduction) are two widely used technologies for industrial denitrification. This paper gives a brief description of the similarities and differences between them.

SNCR (Selective non-catalytic reduction) and SCR(Selective catalytic reduction) are two widely used technologies for industrial denitrification. They all have in common the reduction of nitrogen oxides (NOx) in flue gas, however the methods and processes used will be different.

1, principle and process difference
SCR denitrification technology uses a catalyst to convert NOx into nitrogen (N2) and water (H2O) at a certain temperature and under catalytic action. In SCR denitration technology, ammonia or other suitable reducing agents react with NOx under the action of a catalyst.

SNCR technology is in the absence of catalyst, at the temperature suitable for denitration reaction (temperature range 850℃ to 1100℃), spray into the reducing agent ammonia, urea or hydrogen acid, NOx in the flue gas reduction into harmless nitrogen and water. This technique does not use a catalyst, but a reducing agent must be added at high temperatures.

2. Differences in operating conditions
When SCR denitrification technology is operated at lower temperatures, catalysts are required as a necessary condition, which can increase the complexity and maintenance costs of the system. SNCR technology puts forward additional requirements for boiler design and operation under high temperature conditions.

3. Efficiency and cost differentials
SCR denitration technology compared to SNCR technology, investment and operating costs are relatively high, SCR technology investment is at least several times the investment of SNCR, SCR denitration efficiency can reach more than 90%, SNCR technology denitration efficiency is generally 30%-80%.

4. Environmental impact.
SCR denitrification technology is more environmentally friendly than SNCR technology, but because ammonia is used as a reducing agent, if it is not properly treated, it will still lead to ammonia pollution. In normal operation, SNCR technology may also produce ammonia escape, ozone leakage and other pollution.

5. different scope of application.
Due to its high efficiency and strong stability, SCR denitrification technology is suitable for occasions requiring higher denitrification efficiency, such as petrochemical industry, power plants, power stations, steel, glass, metallurgy and other industries. The cost of SNCR technology is relatively low, so it will be widely used in some sites with low requirements for denitrification efficiency.

SCR and SNCR technology each have advantages and limitations, but the choice of the right denitrification technology, according to the specific industrial applications, environmental requirements and economic benefits of the combination of consideration, with the increasingly strict environmental regulations, denitrification technology innovation, the future we will continue to develop new technologies and solutions.