- SCR flue gas denitration technology
The technique is to add a reducing agent (such as urea) to the flue gas to form N2 and water after the reaction. In the case of a catalyst, the activation temperature of the reaction is from 300 ° C to 400 ° C, which corresponds to the flue gas temperature between the boiler economizer and the air preheater. At present, the denitration efficiency of the technology is about 60% to 90%.
2. SNCR flue gas denitration technology
This technology is a non-selective reducing agent denitration technology, so a higher reaction temperature is required, and the reducing agent is sprayed into the furnace temperature range of 850 ° C to 1100 ° C. The reducing agent (urea) is rapidly decomposed into NH3 and reacted with NOx in the flue gas to form N2 by a furnace. SNCR denitrification technology is relatively inefficient, generally 20% to 50%. The latest research results show that when urea is used as a reducing agent, N2O which destroys ozone in the atmosphere may be generated.
3. SNCR/SCR combined with flue gas denitration technology
The technology is a combination of the above two denitration technologies, and the efficiency is relatively high, generally 60% to 80% efficiency is between SCR and SNCR, and the SCR denitration efficiency in the SNCR-SCR combined denitration process is not more than 30%. The technical system and operation are more complicated, and there are very few projects using this technology.
In summary, the future development trend of denitration technology is the combination of low NOx combustion technology and post-furnace SCR flue gas denitration technology. At the same time, it is necessary to develop a low-load (at this time, the reaction temperature is lower, and the catalyst efficiency of the SCR denitration system is lower). The denitration technology can be implemented in a concrete manner. When the boiler is under low load, the temperature can also reach the catalyst activation reaction temperature. Another area is to add a denitrification device, and another method is to develop a low temperature catalyst.