CN110772915A - Sintering flue gas SCR denitration and whitening system and process - Google Patents
Sintering flue gas SCR denitration and whitening system and process Download PDFInfo
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 194
- 239000003546 flue gas Substances 0.000 title claims abstract description 184
- 238000005245 sintering Methods 0.000 title claims abstract description 45
- 230000002087 whitening effect Effects 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title abstract description 14
- 230000008569 process Effects 0.000 title description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 95
- 238000006243 chemical reaction Methods 0.000 claims abstract description 35
- 238000009833 condensation Methods 0.000 claims abstract description 34
- 230000005494 condensation Effects 0.000 claims abstract description 34
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 31
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 28
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 28
- 239000000779 smoke Substances 0.000 claims abstract description 26
- 238000002347 injection Methods 0.000 claims abstract description 24
- 239000007924 injection Substances 0.000 claims abstract description 24
- 238000010790 dilution Methods 0.000 claims abstract description 17
- 239000012895 dilution Substances 0.000 claims abstract description 17
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 38
- 238000010438 heat treatment Methods 0.000 claims description 35
- 238000005507 spraying Methods 0.000 claims description 35
- 239000000428 dust Substances 0.000 claims description 20
- 229910000831 Steel Inorganic materials 0.000 claims description 15
- 239000010959 steel Substances 0.000 claims description 15
- 239000007789 gas Substances 0.000 claims description 13
- 239000003054 catalyst Substances 0.000 claims description 11
- 239000007921 spray Substances 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 7
- 238000007599 discharging Methods 0.000 claims description 6
- 239000002002 slurry Substances 0.000 claims description 6
- 230000009471 action Effects 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 238000001704 evaporation Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 230000008016 vaporization Effects 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 3
- 238000003912 environmental pollution Methods 0.000 abstract description 2
- 238000000746 purification Methods 0.000 abstract description 2
- 239000003344 environmental pollutant Substances 0.000 description 5
- 231100000719 pollutant Toxicity 0.000 description 5
- 238000010410 dusting Methods 0.000 description 4
- 238000006477 desulfuration reaction Methods 0.000 description 3
- 230000023556 desulfurization Effects 0.000 description 3
- 238000011010 flushing procedure Methods 0.000 description 3
- 238000003303 reheating Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003595 mist Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 238000005453 pelletization Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D50/00—Combinations of methods or devices for separating particles from gases or vapours
- B01D50/40—Combinations of devices covered by groups B01D45/00 and B01D47/00
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
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- General Chemical & Material Sciences (AREA)
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Abstract
The invention relates to a sintering flue gas SCR denitration and whitening system, which comprises a flue gas condensation whitening and demisting dedusting tower, a heat exchange device, a hot blast stove, an ammonia water evaporator, a dilution fan, an ammonia injection grid, an SCR denitration reaction device and a smoke exhaust device, wherein the heat exchange device is arranged between the flue gas condensation whitening and demisting dedusting tower and the SCR denitration reaction device and is used for exchanging heat for the temperature of flue gas before and after denitration, an original flue gas outlet of the heat exchange device is connected with an air inlet of the SCR denitration reaction device through a second main flue, the hot blast stove and the ammonia injection grid are sequentially arranged along the flow direction of the flue gas in the second main flue, and the ammonia water evaporator and the dilution fan are arranged between the ammonia injection grid and an air outlet of the SCR denitration reaction device. The invention can carry out SCR denitration and whitening treatment on the desulfurized sintering flue gas, improve the purification effect on the sintering flue gas desulfurized by a wet method and reduce the environmental pollution.
Description
Technical Field
The invention belongs to the field of sintering flue gas pollutants and flue gas whitening control, and particularly relates to a sintering flue gas SCR denitration whitening system and process.
Background
At present, the steel smelting industry is an industry with high energy consumption and heavy pollution. Sintering flue gas generated in the high-temperature sintering process of steel contains gases of various pollution components, wherein the pollution components comprise particulate matters, NOx, SO2 and other acid gasesThe body is one of the main causes of atmospheric pollution. The current emission standard of atmospheric pollutants for the steel sintering and pelletizing industry (GB 28662-2012) stipulates that the emission limits of particulate matters, NOx and SO2 in sintering flue gas are respectively 50mg/m
3、200mg/m
3、300mg/m
3. However, the treatment of sintering flue gas at the present stage mainly remains in the aspects of desulfurization and dust removal, and the treatment of pollutants such as denitration is not fully developed. Along with the development of economy, the degree of attention of people to the environment is increasing day by day, the requirements of the environment standards in all parts of the country are becoming stricter and stricter, and in order to further improve the quality of the atmospheric environment in China, the ecological environment department publishes a 'letter about the proposal of the ultralow emission modification (quotation of comments) > of iron and steel enterprises' in 2018: the method proposes that all newly-built (including moving) steel projects reach an ultra-low emission level, and the hourly average emission standard of main pollutants of sintering machine heads and pellet roasting flue gas is as follows under the condition that the reference oxygen content is 16 percent: NOx emission concentration < 50mg/Nm
3SO2 emission concentration is less than 35mg/Nm
3And the smoke emission concentration is less than 10mg/Nm
3. Meanwhile, the saturated flue gas after wet desulphurization has a low temperature, and if the saturated flue gas is directly discharged from a chimney and is mixed with outside cold air, water vapor in the flue gas is condensed to form white smoke plume, so that the atmospheric pollution is not only visual pollution, but also substantial pollution. And traditional flue gas denitration treatment process is difficult to adapt to, also can not satisfy new environmental standard moreover, consequently is essential to steel industry sintering section denitration transformation. Under the background, it is necessary to research an SCR denitration and whitening system and process for sintering flue gas after wet desulfurization.
Disclosure of Invention
The invention aims to solve the technical problem of providing an SCR denitration and whitening system and process for sintering flue gas in the prior art, and the SCR denitration and whitening treatment are carried out on the desulfurized sintering flue gas at the same time, so that the purification effect of the sintering flue gas subjected to wet desulfurization is improved, and the environmental pollution is reduced.
The technical scheme adopted by the invention for solving the problems is as follows: a sintering flue gas SCR denitration and de-whitening system comprises a flue gas condensation de-whitening and de-whitening dust removal tower, a heat exchange device, a hot blast stove, an ammonia water evaporator, a dilution fan, an ammonia spraying grid, an SCR denitration reaction device and a smoke exhaust device, wherein a slurry area, a spraying area, a de-fogging and de-dusting area and a heating area are sequentially arranged in the flue gas condensation de-whitening and de-dusting tower from bottom to top, a first main flue is connected between a raw flue gas inlet of the heat exchange device and a gas outlet of the flue gas condensation de-whitening and de-dusting tower, a second main flue is connected between a raw flue gas outlet of the heat exchange device and a gas inlet of the SCR denitration reaction device, a third main flue is connected between a clean flue of the heat exchange device and the gas outlet of the SCR de-whitening and de-dusting tower, the ammonia injection grid is arranged on the second main flue, the ammonia evaporator and the dilution fan are arranged between the ammonia injection grid and the third main flue, the ammonia evaporator is used for evaporating and vaporizing concentrated ammonia water into ammonia gas, the dilution fan is used for introducing part of high-temperature clean flue gas subjected to denitration by the SCR denitration reaction device into the ammonia evaporator to mix with the ammonia gas, and the ammonia injection grid is used for spraying the mixed ammonia gas into the second main flue.
Preferably, the flue gas condensation takes off white defogging gas wash tower includes the tower body, the top of tower body is provided with the chimney, the inside of tower body is supreme from bottom to be provided with thick liquid district, spray zone, defogging dust removal district and the zone of heating in proper order, be provided with a plurality of spray set from bottom to top interval arrangement in the spray zone, be provided with tube bundle formula defogging dust remover in the defogging dust removal district, be provided with heating device in the zone of heating, spray set is used for condensing the flue gas, tube bundle formula defogging dust remover is used for carrying out the defogging dust removal to the flue gas after the condensation, heating device is used for heating the flue gas after the defogging dust removal.
Preferably, the spraying device comprises a plurality of spraying layers, each spraying layer comprises a plurality of atomizing nozzles arranged side by side, a circulating pipeline is arranged between each atomizing nozzle and the slurry area at the bottom of the tower body, and a circulating pump is arranged on each circulating pipeline;
the tube bundle type demisting and dedusting device comprises a plurality of guide tubes which are vertically arranged, two guide vanes which are vertically arranged are arranged in each guide tube, a rotational flow assembly is arranged between the two guide vanes, each rotational flow assembly comprises a straight cylinder and two conical cylinders which are relatively reduced and arranged in the straight cylinder, and the two conical cylinders are vertically symmetrically arranged and are communicated with each other.
Preferably, the heat exchange device is a rotary GGH heat exchanger.
Preferably, the heat source of the hot blast stove is blast furnace gas.
Preferably, one end of the hot blast stove is connected with a blower.
Preferably, the ammonia injection grid comprises a plurality of thin steel pipes which are parallel to each other up and down, a plurality of injection holes which are arranged at intervals along the length direction of the thin steel pipes are formed in the thin steel pipes, and the opening direction of the injection holes is the same as the flowing direction of the flue gas in the second main flue.
Preferably, the SCR denitration reactor is a medium-low temperature SCR denitration reactor, and two catalyst reaction layers and a catalyst reservation layer are disposed in the SCR denitration reactor.
Preferably, an induced draft fan is arranged on the fourth main flue.
The sintering flue gas SCR denitration and whitening process adopts the sintering flue gas SCR denitration and whitening system to carry out denitration and whitening treatment on sintering flue gas subjected to wet desulphurization, and comprises the following specific steps:
step one, a flue gas de-whitening condensation and flue gas demisting and dedusting stage
The sintering flue gas after wet desulphurization enters a flue gas condensation, whitening, demisting and dedusting tower, and passes through a spraying zone, a demisting and dedusting zone and a heating zone in sequence to change saturated flue gas into unsaturated flue gas, so that the purposes of whitening, condensing and demisting and dedusting the flue gas are realized;
step two, a flue gas temperature rising stage
a. Flue gas heat exchange before denitration
The flue gas after being subjected to whitening condensation, demisting and dedusting is subjected to primary temperature rise to about 245 ℃ through a heat exchange device;
b. second heating
Secondarily heating the flue gas subjected to heat exchange to about 280 ℃ through a hot blast stove;
step three, ammonia spraying treatment stage
The concentrated ammonia water is vaporized into ammonia gas in the ammonia water evaporator, part of high-temperature clean flue gas denitrated by the SCR denitration reaction device is introduced into the ammonia water evaporator by the dilution fan to be mixed with the ammonia gas, the mixed ammonia gas is sprayed into the second main flue through the ammonia spraying grid, and the mixed ammonia gas is further mixed with the flue gas which is secondarily heated in the second main flue;
step four, SCR denitration treatment stage
Mixing the secondarily heated flue gas with ammonia gas, then feeding the mixture into an SCR denitration reaction device, mixing the mixture with the flue gas in the SCR denitration reaction device again, fully mixing the ammonia gas with nitrogen oxide in the flue gas, carrying out chemical reaction under the action of a catalyst, and removing the nitrogen oxide;
step five, a smoke cooling stage
Cooling the denitrated high-temperature clean flue gas to 85-90 ℃ through a heat exchange device;
step six, smoke discharging stage
And discharging the denitrated and whitened smoke through the smoke exhaust device after the cooled clean smoke.
Compared with the prior art, the invention has the advantages that:
1. the spray device, the tube bundle type demisting and dedusting tower and the heating device are sequentially arranged in the flue gas condensation, de-whitening and demisting and dedusting tower from bottom to top, the structure in the tower is compact, the field is saved, the operation is simple, the operation cost is low, the safety and the reliability are realized, the dedusting efficiency is high, the flue gas heating range is lower, and the better dedusting and de-whitening effects can be realized.
2. Because the tube bundle type demisting and dedusting device is arranged in the flue gas condensation and whitening demisting and dedusting tower, the field is saved, meanwhile, small particles in the flue gas can be removed, the denitration of a follow-up SCR catalyst is not influenced, and the dust in the flue gas is up to standard.
3. The chimney is arranged at the top of the flue gas condensation, whitening, demisting and dedusting tower, so that the field is saved, the cost is reduced, and the whitened flue gas after being condensed and reheated after dedusting reaches the standard can be directly discharged.
4. The heat exchange device realizes heat exchange of flue gas before and after denitration, the low-temperature flue gas temperature before denitration is heated by the heat exchanger for the first time, the flue gas is heated by the hot blast stove for the second time, the flue gas temperature is heated to the working temperature of the SCR catalyst, the high-temperature clean flue gas temperature after denitration is subjected to heat exchange by the heat exchange device, the flue gas temperature is reduced to the flue gas temperature, heat exchange is carried out by utilizing heat difference transfer, and energy is greatly saved.
5. The flue gas condensation, whitening, demisting and dedusting tower and the heat exchange device work cooperatively, so that the desulfurized saturated wet flue gas is firstly condensed and cooled to remove the moisture content in the flue gas, the denitrated clean flue gas is cooled to 85-90 ℃ through the heat exchange device, and the temperature is equivalent to a reheating section for whitening by a condensation reheating method, namely, the flue gas is discharged after being heated, and finally the phenomenon of white smoke plume is eliminated, and the flue gas whitening is completed.
6. According to the invention, the denitrated clean flue gas is introduced into the ammonia water evaporator through the dilution fan, so that the concentration of the ammonia gas can be diluted, the concentration of nitric oxide in the flue gas can be reduced, meanwhile, heat energy can be effectively recycled in the SCR denitration reaction device, and energy is saved.
Drawings
FIG. 1 is a schematic diagram of a sintering flue gas SCR denitration and de-whitening system of the present invention.
Fig. 2 is a schematic structural diagram of a flue gas condensation, de-whitening, demisting and dedusting tower.
FIG. 3 is a schematic view of the internal structure of a flow guide tube in a tube bundle type mist and dust remover.
FIG. 4 is a top view of a tube bundle defogging dust collector.
Wherein:
the system comprises a flue gas condensation, whitening, demisting and dedusting tower 1, a tower body 101, a chimney 102, a spraying device 103, a spraying layer 103.1, an atomizing nozzle 103.2, a tube bundle type demisting and dedusting device 104, a guide tube 104.1, guide vanes 104.2, a straight cylinder 104.3, a conical cylinder 104.4 and a heating device 105
The heat exchange device 2, a raw flue gas inlet 21, a raw flue gas outlet 22, a purified flue gas inlet 23 and a purified flue gas outlet 24
A blower 3,
A hot blast furnace 4,
An ammonia water evaporator 5,
A dilution fan 6,
An ammonia injection grid 7,
An SCR denitration reaction device 8,
First main flue 11
Second main flue 12
Third main flue 13
Fourth main flue 14
A bypass flue 15.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
Referring to fig. 1-4, the sintering flue gas SCR denitration and de-whitening system according to the present invention comprises a flue gas condensation de-whitening and de-misting tower 1, a heat exchange device 2, a hot-air furnace 4, an ammonia water evaporator 5, a dilution fan 6, an ammonia injection grid 7, an SCR denitration reaction device 8 and a smoke exhaust device 10, wherein a first main flue 11 is connected between an original flue gas inlet 21 at the lower portion of the heat exchange device 2 and an air outlet of the flue gas condensation de-whitening and de-misting tower 1, a second main flue 12 is connected between an original flue gas outlet 22 at the upper portion of the heat exchange device 2 and an air inlet of the SCR denitration reaction device 8, a third main flue 13 is connected between a clean flue gas inlet 23 at the upper portion of the heat exchange device 2 and an air outlet of the SCR denitration reaction device 8, a fourth main flue 14 is connected between a clean flue gas outlet 24 at the lower portion of the heat exchange device 2 and an air inlet of the smoke exhaust device, a branch flue 15 is connected between the hot blast stove 4 and the second main flue 12, the ammonia injection grid 7 is arranged on the second main flue 12, the ammonia water evaporator 5 and the dilution fan 6 are arranged between the ammonia injection grid 7 and the third main flue 13, the ammonia water evaporator 5 is used for evaporating and vaporizing concentrated ammonia water into ammonia gas, the dilution fan 6 is used for introducing part of high-temperature clean flue gas denitrated by the SCR denitration reaction device 8 into the ammonia water evaporator 5, mixing the high-temperature clean flue gas with the ammonia gas and diluting the ammonia gas concentration, and the ammonia injection grid 7 is used for injecting the mixed ammonia gas into the second main flue 12;
the flue gas condensation, de-whitening, demisting and dedusting tower 1 comprises a tower body 101, a chimney 102 is arranged at the top of the tower body 101, a slurry area, a spraying area, a demisting and dedusting area and a heating area are sequentially arranged in the tower body 101 from bottom to top, a plurality of spraying devices 103 are arranged in the spraying area at intervals from bottom to top, a tube bundle type demisting and dedusting device 104 is arranged in the demisting and dedusting area, a heating device 105 is arranged in the heating area, the spraying devices 103 are used for condensing flue gas, the tube bundle type demisting and dedusting device 104 is used for demisting and dedusting condensed flue gas, and the heating device 105 is used for heating the flue gas after demisting and dedusting, so that saturated flue gas is changed into unsaturated flue gas, thereby realizing demisting and dedusting of flue gas and de-whitening of flue gas, and achieving;
the spraying device 103 comprises a plurality of spraying layers 103.1, the spraying layers 103.1 comprise a plurality of atomizing nozzles 103.2 which are arranged side by side, a circulating pipeline is arranged between the atomizing nozzles 103.2 and a slurry area at the bottom of the tower body 101, and a circulating pump is arranged on the circulating pipeline;
the spraying layer 103.1 is provided with at least three layers;
the tube bundle type demisting and dedusting device 104 comprises a plurality of guide tubes 104.1 which are vertically arranged, two guide vanes 104.2 which are vertically arranged are arranged in the guide tube 104.1, a rotational flow component is arranged between the two guide vanes 104.2, the rotational flow component comprises a straight cylinder 104.3 and two relatively reduced conical cylinders 104.4 which are arranged in the straight cylinder 104.3, the two conical cylinders 104.4 are vertically and symmetrically arranged and are communicated with each other, the large caliber of the conical cylinder 104.4 is the same as the inner diameter of the straight cylinder 104.3, and the flow velocity of flue gas can be accelerated by the matching use of the guide vanes 104.2 and the rotational flow component, so that mist and micro-dust particles in the flue gas can be fully separated and purified;
the heat source of the heating device 105 heats the demisted and dedusted flue gas by adopting flue gas heating or electric heating, and the flue gas is discharged through the chimney 102 when the temperature of the flue gas is heated to the temperature set by the local environment;
the spraying area and the demisting and dedusting area are respectively provided with a spraying flushing device and a demister flushing device which are respectively used for periodically flushing the spraying device 103 and the tube bundle type demisting and dedusting device 104 so as to avoid blockage caused by accumulation of smoke dust;
the heat exchange device 2 is a rotary GGH heat exchanger, and has the advantages of mature technology, corrosion resistance, uneasiness for ash blocking and the like, the heat exchange device 2 is used for carrying out heat exchange treatment on low-temperature raw flue gas treated by the flue gas condensation, whitening, demisting and dedusting tower 1 and high-temperature clean flue gas after being denitrated by the SCR denitration reaction device 8, namely, carrying out primary heating treatment on the low-temperature raw flue gas and cooling treatment on the high-temperature clean flue gas, the heat exchange device 2 realizes flue gas heat exchange before and after denitration, and effectively saves energy;
the heat source of the hot blast stove 4 adopts blast furnace gas to carry out secondary heating treatment on the flue gas, so that the temperature of the flue gas is heated to the temperature range required by the SCR denitration reaction device 8;
one end of the hot blast stove 4 is connected with a blower 3, and the combustion temperature of the hot blast stove 4 is adjusted through the air doping amount of the blower 3;
the ammonia water evaporator 5 is a high temperature and high pressure resistant container, concentrated ammonia water and compressed air are atomized under the action of a spray gun arranged in the ammonia water evaporator 5, and are heated under the action of high temperature clean flue gas after denitration introduced by a dilution fan 6, so that the concentrated ammonia water is vaporized into ammonia gas and is mixed with the flue gas, and the mixed ammonia gas is sprayed into the second main flue 12 through an ammonia spraying grid 7 and is further mixed with the original flue gas in the second main flue 12;
the ammonia injection grid 7 comprises a plurality of thin steel pipes which are parallel to each other up and down, a plurality of injection holes which are arranged at intervals along the length direction of the thin steel pipes are formed in the thin steel pipes, and the opening direction of the injection holes is the same as the flowing direction of the flue gas in the second main flue 12;
the SCR denitration reactor 8 is a medium-low temperature SCR denitration reactor, and two catalyst reaction layers and a catalyst reservation layer are arranged in the SCR denitration reactor;
and an induced draft fan 9 is arranged on the fourth main flue 14.
A sintering flue gas SCR denitration and de-whitening process adopts a sintering flue gas SCR denitration and de-whitening system to perform denitration and de-whitening treatment on sintering flue gas subjected to wet desulphurization, and comprises the following specific steps:
step one, a flue gas de-whitening condensation and flue gas demisting and dedusting stage
The sintering flue gas after wet desulphurization enters a flue gas condensation, whitening, demisting and dedusting tower, and passes through a spraying zone, a demisting and dedusting zone and a heating zone in sequence to change saturated flue gas into unsaturated flue gas, so that the purposes of whitening, condensing and demisting and dedusting the flue gas are realized;
the flue gas is subjected to whitening condensation by a spraying device, partial pollutants and particulate matters in the flue gas are removed, the temperature of the flue gas is further reduced by a tube bundle type demisting dust remover, the moisture content in saturated wet flue gas is removed, particulate matters, liquid drops and the like in the flue gas can be removed, and finally the temperature of the flue gas is heated to the temperature set by the local environment (over 75 ℃ in summer and over 80 ℃ in winter) by a heating zone and then is discharged into a first main flue through a chimney;
step two, a flue gas temperature rising stage
a. Flue gas heat exchange before denitration
The flue gas after being subjected to whitening condensation, demisting and dedusting is subjected to primary temperature rise to about 245 ℃ through a heat exchange device;
b. second heating
Secondarily heating the flue gas subjected to heat exchange to about 280 ℃ through a hot blast stove;
step three, ammonia spraying treatment stage
The concentrated ammonia water is vaporized into ammonia gas in the ammonia water evaporator, part of high-temperature clean flue gas denitrated by the SCR denitration reaction device is introduced into the ammonia water evaporator by the dilution fan to be mixed with the ammonia gas, the mixed ammonia gas is sprayed into the second main flue through the ammonia spraying grid, and the mixed ammonia gas is further mixed with the flue gas which is secondarily heated in the second main flue;
step four, SCR denitration treatment stage
The flue gas after secondary heating and ammonia gas are mixed and then enter an SCR denitration reaction device, and are mixed with the flue gas in the SCR denitration reaction device again, the ammonia gas (NH3) is fully mixed with nitrogen oxide (NOx) in the flue gas, a chemical reaction is carried out under the action of a catalyst, the NOx is removed, and the reaction equation is as follows:
step five, a smoke cooling stage
Cooling the denitrated high-temperature clean flue gas to 85-90 ℃ through a heat exchange device;
step six, smoke discharging stage
And discharging the denitrated and whitened smoke through the smoke exhaust device after the cooled clean smoke.
After the process flow, the content concentration of nitrogen oxide in the sintering flue gas after wet desulphurization can reach the standard of ultra-clean emission, namely NOx is less than or equal to 50mg/m
3In addition, after the desulfurized sintering flue gas is treated by a condensation reheating method, the emission temperature of the desulfurized sintering flue gas is about 85-90 ℃, and the aims of flue gas denitration and flue gas whitening are successfully realized.
In addition to the above embodiments, the present invention also includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of the claims of the present invention.
Claims (10)
1. The utility model provides a sintering flue gas SCR denitration and white-removing system which characterized in that: comprises a flue gas condensation de-whitening demisting and dedusting tower (1), a heat exchange device (2), a hot blast stove (4), an ammonia evaporator (5), a dilution fan (6), an ammonia spraying grid (7), an SCR denitration reaction device (8) and a smoke exhaust device (10), wherein a slurry area, a spraying area, a demisting and dedusting area and a heating area are sequentially arranged in the flue gas condensation de-whitening and demisting and dedusting tower (1) from bottom to top, a first main flue (11) is connected between an original flue gas inlet (21) of the heat exchange device (2) and a gas outlet of the flue gas condensation de-whitening and demisting and dedusting tower (1), a second main flue (12) is connected between an original flue gas outlet (22) of the heat exchange device (2) and a gas inlet of the SCR denitration reaction device (8), and a third main flue (13) is connected between a clean flue gas inlet (23) of the heat exchange device (2) and a gas outlet of the SCR denitration reaction device (8, a fourth main flue (14) is connected between the clean flue gas outlet (24) of the heat exchange device (2) and the gas inlet of the smoke exhaust device (10), the hot blast stove (4) and the ammonia injection grid (7) are sequentially arranged along the flow direction of the flue gas in the second main flue (12), a branch flue (15) is connected between the hot blast stove (4) and the second main flue (12), the ammonia injection grid (7) is arranged on the second main flue (12), the ammonia water evaporator (5) and the dilution fan (6) are arranged between the ammonia injection grid (7) and the third main flue (13), the ammonia water evaporator (5) is used for evaporating and vaporizing concentrated ammonia water into ammonia gas, the dilution fan (6) is used for introducing part of high-temperature clean flue gas denitrated by the SCR denitration reaction device (8) into the ammonia water evaporator (5) to be mixed with the ammonia gas, the ammonia injection grid (7) is used for injecting the mixed ammonia gas into the second main flue (12).
2. The sintering flue gas SCR denitration and de-whitening system of claim 1, characterized in that: flue gas condensation takes off white defogging gas wash tower (1) and includes tower body (101), the top of tower body (101) is provided with chimney (102), the inside of tower body (101) has set gradually thick liquids district, spray zone, defogging dust removal district and the zone of heating from bottom to top, be provided with a plurality of spray set (103) of supreme interval arrangement from bottom to top in the spray zone, be provided with tube bank formula defogging dust remover (104) in the defogging dust removal district, be provided with heating device (105) in the zone of heating, spray set (103) are used for condensing the flue gas, tube bank formula defogging dust remover (104) are used for carrying out the defogging to the flue gas after the condensation and remove dust, heating device (105) are used for heating the flue gas after the defogging removes dust.
3. The sintering flue gas SCR denitration and de-whitening system of claim 2, characterized in that: the spraying device (103) comprises a plurality of spraying layers (103.1), the spraying layers (103.1) comprise a plurality of atomizing nozzles (103.2) which are arranged side by side, a circulating pipeline is arranged between the atomizing nozzles (103.2) and a slurry area at the bottom of the tower body (101), and a circulating pump is arranged on the circulating pipeline;
the tube bundle type demisting and dedusting device (104) comprises a plurality of guide tubes (104.1) which are vertically arranged, two guide vanes (104.2) which are vertically arranged are arranged in the guide tubes (104.1), a rotational flow component is arranged between the two guide vanes (104.2), the rotational flow component comprises a straight cylinder (104.3) and two conical cylinders (104.4) which are relatively reduced and arranged in the straight cylinder (104.3), and the two conical cylinders (104.4) are vertically symmetrically arranged and are communicated with each other.
4. The sintering flue gas SCR denitration and de-whitening system of claim 1, characterized in that: the heat exchange device (2) is a rotary GGH heat exchanger.
5. The sintering flue gas SCR denitration and de-whitening system of claim 1, characterized in that: the heat source of the hot blast stove (4) adopts blast furnace gas.
6. The sintering flue gas SCR denitration and de-whitening system of claim 5, characterized in that: one end of the hot blast stove (4) is connected with a blower (3).
7. The sintering flue gas SCR denitration and de-whitening system of claim 1, characterized in that: the ammonia injection grid (7) comprises a plurality of thin steel pipes which are parallel to each other up and down, a plurality of injection holes which are arranged at intervals along the length direction of the thin steel pipes are formed in the thin steel pipes, and the opening direction of the injection holes is the same as the flowing direction of smoke in the second main flue (12).
8. The sintering flue gas SCR denitration and de-whitening system of claim 1, characterized in that: the SCR denitration reactor (8) is a medium-low temperature SCR denitration reactor, and two catalyst reaction layers and a catalyst reservation layer are arranged in the SCR denitration reactor.
9. The sintering flue gas SCR denitration and de-whitening system of claim 1, characterized in that: and an induced draft fan (9) is arranged on the fourth main flue (14).
10. The sintering flue gas SCR denitration and whitening technology is characterized in that: the sintering flue gas SCR denitration and whitening system of claim 1 is used for carrying out denitration and whitening treatment on sintering flue gas subjected to wet desulphurization, and comprises the following specific steps:
step one, a flue gas de-whitening condensation and flue gas demisting and dedusting stage
The sintering flue gas after wet desulphurization enters a flue gas condensation, whitening, demisting and dedusting tower, and passes through a spraying zone, a demisting and dedusting zone and a heating zone in sequence to change saturated flue gas into unsaturated flue gas, so that the purposes of whitening, condensing and demisting and dedusting the flue gas are realized;
step two, a flue gas temperature rising stage
a. Flue gas heat exchange before denitration
The flue gas after being subjected to whitening condensation, demisting and dedusting is subjected to primary temperature rise to about 245 ℃ through a heat exchange device;
b. second heating
Secondarily heating the flue gas subjected to heat exchange to about 280 ℃ through a hot blast stove;
step three, ammonia spraying treatment stage
The concentrated ammonia water is vaporized into ammonia gas in the ammonia water evaporator, part of high-temperature clean flue gas denitrated by the SCR denitration reaction device is introduced into the ammonia water evaporator by the dilution fan to be mixed with the ammonia gas, the mixed ammonia gas is sprayed into the second main flue through the ammonia spraying grid, and the mixed ammonia gas is further mixed with the flue gas which is secondarily heated in the second main flue;
step four, SCR denitration treatment stage
Mixing the secondarily heated flue gas with ammonia gas, then feeding the mixture into an SCR denitration reaction device, mixing the mixture with the flue gas in the SCR denitration reaction device again, fully mixing the ammonia gas with nitrogen oxide in the flue gas, carrying out chemical reaction under the action of a catalyst, and removing the nitrogen oxide;
step five, a smoke cooling stage
Cooling the denitrated high-temperature clean flue gas to 85-90 ℃ through a heat exchange device;
step six, smoke discharging stage
And discharging the denitrated and whitened smoke through the smoke exhaust device after the cooled clean smoke.
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| CN111482071A (en) * | 2020-04-14 | 2020-08-04 | 中钢集团天澄环保科技股份有限公司 | Sintering flue gas multi-pollutant cooperative purification and waste heat utilization system and process |
| CN112546864A (en) * | 2020-11-16 | 2021-03-26 | 中国华电科工集团有限公司 | SCR denitration system |
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