Flue gas denitrating technique with preposed whirlwind beforehand dust removal SCR

Abstract

The invention discloses a preposing cyclone pre-dedusting SCR flue gas denitration technique. The flue gas extracted from a boiler economizer (12) primarily passes through a high temperature resistant cyclone separator (6), then passes through a flue gas current equalizer (7) and a static mixer (2) to unify the flow direction of the flue gas evenly; meanwhile, the flue gas after being mixed evenly with ammonia is preprocessed before reacting with a catalyst of an SCR reactor (3); finally, the flue gas is output after the temperature is reduced through an air preheater (4) and the flue gas is dedusted through an electrical precipitator (5). The invention reduces the volume of the catalyst and the SCR reactor, reduces the requirements of the support, eliminates an SCR bypass and greatly reduces engineering cost of the SCR; meanwhile, the invention also prolongs the service life of the catalyst and the cleaning period of the air preheater without installing a soot blower or prolonging the period of sootblowing.

Description

technical field [0001] The invention belongs to a flue gas denitrification process, in particular to a pre-cyclone pre-dust removal SCR flue gas denitrification process. Background technique [0002] The traditional flue gas denitrification device is shown in Figure 5. The upper part of the SCR reactor 3 is connected to the flue gas inlet pipe 8 drawn from the boiler 10. The flue gas inlet pipe 8 is provided with a static mixer 2, and the front of the static mixer 2 An ammonia injection grid 1 is provided, and the lower part of the SCR reactor 3 is connected to the electrostatic precipitator 5 through the flue gas output pipe 9, and the flue gas output pipe 9 between the electrostatic precipitator 5 and the SCR reactor 3 is provided with an air pre-set The heater 4 , the air input pipe 13 entering the boiler 10 is connected to the boiler 10 through the air preheater 4 through the fan 11 , and the nozzle of the ammonia injection grid 1 faces the SCR reactor 3 . Baffles 13 ar...

AI Technical Summary

Problems solved by technology

[0003] Due to the high concentration of flue gas dust in the SCR reactor, the fly ash contained in it is easy to cause catalyst wear and poisoning, shorten the service life of the catalyst, and increase the operating cost; among them, the large particle fly ash (especially popcorn fly ash) is particularly It is easy to cause catalyst clogging. In order to reduce the probability of catalyst clogging, it is generally necessary to choose a catalyst with a large pore size, which will result in a larger catalyst volume and increase the investment cost of the SCR project. If the catalyst is clogged, the furnace must be shut down, and the loss is huge. Therefore, it is often necessary to set up an SCR bypass 6 in the system design, which will further increase the investment cost of SCR denitrification; in addition, due to the high concentration of fly ash, the leakage of NH from the denitrification reaction 3 with SO 3 and H 2 O will generate substances such as ammonium bisulfate (ABS), which has a relatively high viscosity, and will cause dust to accumulate on the surface of the air preheater, causing contamination and corrosion of the air preheater, and blockage of the air preheater 4. Therefore, it is necessary to increase the cleaning frequency of the air preheater 4

[0004] In addition, in the traditional process, due to the wear and tear of the denitrification catalyst, the heavy metals of the worn denitrification catalyst will be enriched in the dust of the electrostatic precipitator 5, resulting in a high concentration of heavy metals in the fly ash of the electrostatic precipitator, which will affect the application of fly ash in power plants

[0005] The current trend is to cancel the SCR bypass 6, which will undoubtedly further increase the risk of downtime due to fly ash clogging, and the traditional SCR process will be more severely challenged

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