CN112604473A - Chain grate-rotary kiln tail gas nitrogen oxide removal coupling method - Google Patents
Chain grate-rotary kiln tail gas nitrogen oxide removal coupling method Download PDFInfo
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- CN112604473A CN112604473A CN202011302178.3A CN202011302178A CN112604473A CN 112604473 A CN112604473 A CN 112604473A CN 202011302178 A CN202011302178 A CN 202011302178A CN 112604473 A CN112604473 A CN 112604473A
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- nitrogen oxides
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 164
- 239000007789 gas Substances 0.000 title claims abstract description 28
- 238000010168 coupling process Methods 0.000 title claims abstract description 26
- 239000003546 flue gas Substances 0.000 claims abstract description 73
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 68
- 238000002347 injection Methods 0.000 claims abstract description 28
- 239000007924 injection Substances 0.000 claims abstract description 28
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 28
- 230000003647 oxidation Effects 0.000 claims abstract description 27
- 238000001035 drying Methods 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 13
- 230000003009 desulfurizing effect Effects 0.000 claims abstract description 11
- 239000000428 dust Substances 0.000 claims abstract description 8
- 238000006722 reduction reaction Methods 0.000 claims abstract description 5
- 239000012670 alkaline solution Substances 0.000 claims abstract description 4
- 238000000746 purification Methods 0.000 claims abstract description 4
- 239000003638 chemical reducing agent Substances 0.000 claims description 25
- 239000007921 spray Substances 0.000 claims description 25
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 16
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 16
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 15
- 239000004202 carbamide Substances 0.000 claims description 15
- 239000000243 solution Substances 0.000 claims description 14
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 8
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 239000003054 catalyst Substances 0.000 claims description 6
- 238000010790 dilution Methods 0.000 claims description 6
- 239000012895 dilution Substances 0.000 claims description 6
- 230000007704 transition Effects 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 5
- 230000009471 action Effects 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 4
- 239000012530 fluid Substances 0.000 claims description 3
- 229910000069 nitrogen hydride Inorganic materials 0.000 claims description 3
- 239000012717 electrostatic precipitator Substances 0.000 claims 1
- 230000008878 coupling Effects 0.000 abstract description 3
- 238000005859 coupling reaction Methods 0.000 abstract description 3
- 238000005516 engineering process Methods 0.000 abstract description 3
- 238000010531 catalytic reduction reaction Methods 0.000 abstract description 2
- 239000008188 pellet Substances 0.000 description 6
- 229910002651 NO3 Inorganic materials 0.000 description 5
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000005453 pelletization Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000863 Ferronickel Inorganic materials 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
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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
- B01D53/75—Multi-step processes
-
- 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
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
-
- 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
- B01D53/76—Gas phase processes, e.g. by using aerosols
-
- 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
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
-
- 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
- B01D53/77—Liquid phase processes
- B01D53/79—Injecting reactants
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
- F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
-
- 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
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2067—Urea
-
- 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
Abstract
The invention discloses a chain grate-rotary kiln tail gas nitrogen oxide removal coupling method, which comprises the following steps: high-temperature flue gas discharged from the rotary kiln enters an SNCR (selective non-catalytic reduction) denitration injection system, and an SNCR non-selective reduction reaction is carried out in the SNCR denitration injection system to remove part of nitrogen oxides; then the flue gas passes through a chain grate preheating section, a chain grate drying section II, a chain grate drying section I, an electrostatic dust collector, a main exhaust fan and an oxidation and denitration system in sequence, and is oxidizedNO in flue gas in denitration system is oxidized into NO2Finally, the flue gas passes through a desulfurizing tower, and NO in the flue gas2Absorbed by the alkaline solution in the desulfurizing tower to realize the removal and purification of nitrogen oxides. The coupling method for removing nitrogen oxides in tail gas of the chain grate-rotary kiln adopts a denitration coupling technology of an SNCR + oxidation method, adopts SNCR denitration at a high-temperature section, adopts denitration at a low-temperature section by an oxidation method, has higher denitration efficiency, and meets the requirement of ultra-clean emission.
Description
Technical Field
The invention belongs to the technical field of tail gas treatment, and particularly relates to a chain grate-rotary kiln tail gas nitrogen oxide removal coupling method.
Background
The grate-rotary kiln pelletizing technology is a pelletizing process of drying and preheating green pellets by adopting a grate and pelletizing and roasting the pellets by utilizing a rotary kiln, and the synergistic effect of the grate and the rotary kiln is required in the production process. The production process of the grate-rotary kiln pellets generates a large amount of flue gas during combustion, the flue gas contains high-content nitrogen oxides, and the nitrogen oxides directly discharged into the atmosphere can cause environmental pollution and influence the ecology and the human health. Therefore, before discharging, the flue gas generated in the production of the grate-rotary kiln pellets needs to be subjected to denitration treatment.
In the prior art, for the treatment of tail gas of a grate-rotary kiln, chinese patent application No. 201610919737.2 discloses a grate-rotary kiln denitration system, which comprises a first preheating section and a second preheating section for heating pellets, and further comprises a denitration device for removing nitrogen oxides in flue gas, wherein the denitration device is arranged in an inner cavity of the second preheating section, and the denitration device not only can realize denitration reaction of flue gas, but also can effectively utilize each device of the grate-rotary kiln denitration system to realize denitration reaction, thereby reducing the occupied area, saving energy consumption, and reducing equipment investment and operation cost. The SNCR denitration method is adopted, so that the denitration efficiency is limited, and the ultra-clean emission requirement is difficult to meet. Although the high-temperature flue gas area in the chain grate machine can meet the temperature required by the SNCR reaction, compared with areas such as a boiler furnace chamber and the like in which the SNCR is conventionally applied, the space of the high-temperature area of the chain grate machine is very narrow and small, and the SNCR cannot complete the full reaction, so that the denitration is difficult to realize effectively.
The Chinese patent with application number of 201810440905.9 discloses a grate rotary kiln denitration system and a denitration method, wherein the grate rotary kiln denitration system comprises a grate, a rotary kiln and a ring cooling machine which are sequentially connected, the grate comprises an air blowing drying section, an air draft drying section, a first preheating section and a second preheating section which are sequentially connected, the denitration system further comprises a denitration reactor, the second preheating section is provided with a flue gas outlet, the air draft drying section is provided with a flue gas inlet, the denitration reactor is connected between the flue gas outlet of the second preheating section and the flue gas inlet of the air draft drying section, and a reducing agent injection device is further connected between the denitration reactor and the flue gas outlet of the second preheating section. The denitration method of the rotary kiln of the chain grate comprises the following steps: and leading out the flue gas in the second preheating section to the outside of the chain grate, spraying a reducing agent into the flue gas by using a reducing agent spraying device, carrying out denitration treatment on the flue gas by using a denitration reactor, and then conveying the denitrated flue gas to an air draft drying section. The method adopts SCR denitration, and has stable denitration efficiency, but the defects of high one-time investment cost and complex system, the service life of the catalyst adopted for denitration is usually only three years, the catalyst needs to be replaced, and the operation cost is also high. Therefore, a treatment method which has high denitration efficiency and meets the requirement of ultra-clean emission needs to be designed.
Disclosure of Invention
The invention aims to solve the defects in the prior art and provide a coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln.
In order to achieve the purpose, the invention adopts the technical scheme that: a coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln comprises the following steps: high-temperature flue gas discharged from the rotary kiln enters an SNCR (selective non-catalytic reduction) denitration injection system, and an SNCR non-selective reduction reaction is carried out in the SNCR denitration injection system to remove part of nitrogen oxides; then the flue gas passes through a chain grate preheating section, a chain grate drying section II, a chain grate drying section I, an electrostatic dust collector, a main exhaust fan and an oxidation and denitration system in sequence, and is subjected to oxidation and denitrationOxidation of NO in flue gas in nitrate system to NO2Finally, the flue gas passes through a desulfurizing tower, and NO in the flue gas2Absorbed by the alkaline solution in the desulfurizing tower to realize the removal and purification of nitrogen oxides.
In a preferred embodiment, the SNCR denitration injection system is disposed in a transition flue between the tail section of the rotary kiln and the preheating section of the grate.
In a preferred embodiment, the SNCR denitration injection system is provided with a plurality of spray guns for injecting a reducing agent, and the reducing agent is one of ammonia water and a urea solution.
Preferably, the reducing agent is sprayed into a region with the temperature of 850-1150 ℃, and the reducing agent is rapidly thermally decomposed to obtain NH3Under the action of no catalyst, the NOx in the high-temperature flue gas is subjected to SNCR reaction to generate N2。
In a preferred embodiment, the diluted concentration of the ammonia water is 10% to 15%, and the diluted concentration of the urea solution is 10% to 15%.
Preferably, 2-10 spray guns are uniformly distributed in the transition flue at intervals, and the spray guns adopt double-fluid spray guns and are provided with cooling air; the nozzle angle of the spray gun is 20-90 degrees.
In a preferred embodiment, the oxidation denitration system employs ozone denitration or hydrogen peroxide oxidation denitration.
In a preferred embodiment, the oxidation denitration system is provided with an ozone injection device in the form of an injection grid.
Preferably, the temperature of the flue gas is reduced from 1150-1110 ℃ to 420-480 ℃ through a preheating section of a chain grate, the flue gas is conveyed to a drying section I through a fan, the temperature is reduced from 260-350 ℃ to 60-180 ℃, the flue gas is mixed with hot air at 230-300 ℃ of a drying section II of the chain grate, and finally the mixture is converged to form mixed flue gas with the temperature of less than 170 ℃.
Preferably, the temperature of the flue gas entering the electrostatic dust collector is less than 170 ℃; the temperature of flue gas entering the oxidation and denitration system is 150-200 ℃; the temperature of the flue gas entering the desulfurizing tower is less than 150 ℃.
Compared with the prior art, the invention has the beneficial effects that:
firstly, the coupling method for removing nitrogen oxides in tail gas of the chain grate-rotary kiln adopts a denitration coupling technology of an SNCR + oxidation method, SNCR denitration is adopted in a high-temperature section, and denitration is adopted in a low-temperature section, so that the denitration efficiency is higher, and the ultra-clean emission requirement is met.
Secondly, the coupling method for removing nitrogen oxides in tail gas of the chain grate-rotary kiln sprays reducing agents between the preheating section of the chain grate and the rotary kiln, removes the nitrogen oxides by a reduction method, oxidizes the residual nitrogen oxides in the flue gas by an oxidation method at a wet desulphurization inlet, and finally absorbs the residual nitrogen oxides by limestone slurry in an absorption tower, thereby further improving the denitration efficiency and achieving the ultralow emission of less than or equal to 50mg/Nm3The concentration of nitrogen oxides.
Thirdly, the coupling method for removing nitrogen oxide in tail gas of the chain grate-rotary kiln carries out oxidation denitration on the nitrogen oxide escaping from low-temperature flue gas after the nitrogen oxide in the front-end high-temperature flue gas is reduced and removed by the SNCR system, the escaping nitrogen oxide is removed, the nitrogen oxide is oxidized into high-valence nitrogen oxide and then absorbed by back-end alkali liquor to form nitrate, and then the nitrate is recycled together with gypsum, so that NO generated in the tail gas generated in the production process of oxidized pellets of the chain grate-rotary kiln can be effectively reducedxThe concentration of (c).
Drawings
FIG. 1 is a schematic structural diagram of a chain grate-rotary kiln tail gas nitrogen oxide removal coupling system;
in the figure: the method comprises the following steps of 1-rotary kiln, 2-SNCR denitration injection system, 3-grate preheating section, 4-grate drying section II, 5-grate drying section I, 6-electrostatic dust collector, 7-main exhaust fan, 8-oxidation denitration system, 9-desulfurizing tower, 10-spray gun and 11-ozone injection device.
Detailed Description
The present invention will be described in further detail with reference to specific examples to facilitate the clear understanding of the invention, but the present invention is not limited thereto.
The invention relates to a grate-rotary kilnThe tail gas nitrogen oxide removal coupling method comprises the following steps: high-temperature flue gas discharged from the rotary kiln 1 enters an SNCR denitration injection system 2, and an SNCR non-selective reduction reaction is carried out in the SNCR denitration injection system 2 to remove part of nitrogen oxides; then the flue gas passes through a chain grate preheating section 3, a chain grate drying section II 4, a chain grate drying section I5, an electrostatic dust collector 6, a main exhaust fan 7 and an oxidation and denitration system 8 in sequence, and NO in the flue gas is oxidized into NO in the oxidation and denitration system 82Finally, the flue gas passes through a desulfurizing tower 9, NO in the flue gas2Absorbed by the alkaline solution in the desulfurizing tower to realize the removal and purification of nitrogen oxides.
In the technical scheme, the SNCR denitration injection system 2 is arranged in a transition flue between the tail section of the rotary kiln 1 and the preheating section 3 of the chain grate machine. The temperature interval between the tail section of the rotary kiln 1 and the preheating section 3 of the chain grate machine is in accordance with the reaction temperature of 850-1250 ℃ of SNCR denitration. The SNCR denitration injection system 2 is provided with a plurality of spray guns 10 for injecting a reducing agent, wherein the reducing agent adopts one of ammonia water and urea solution. Spraying the reducing agent into a region with the temperature of 850-1150 ℃, and quickly thermally decomposing the reducing agent to obtain NH3Under the action of no catalyst, the NOx in the high-temperature flue gas is subjected to SNCR reaction to generate N2. In the temperature range of 850-1150 ℃, under the action of no catalyst, ammonia water or urea and other amino reducing agents can selectively reduce NOx in the flue gas and basically do not react with O in the flue gas2And (4) acting.
In the technical scheme, the reducing agent in the SNCR denitration injection system 2 is selected, ammonia water or urea solution can be selected as the reducing agent, and the reducing agent is selected according to the existing reducing agent type in a plant area or the economy of local purchase price. If 20% ammonia water is selected, the 20% ammonia water needs to be diluted to 10% -15% through a dilution metering distribution system, and then the diluted ammonia water is uniformly sprayed into the flue through a spray gun for denitration. When 20% ammonia water is used as the reducing agent, the reducing agent can be purchased in the market, or the ammonia water is prepared in a factory. The ammonia area equipment generally comprises an ammonia water storage tank, a dilution water storage tank, an ammonia water delivery pump and a dilution water delivery pump. If ammonia water needs to be prepared, an ammonia water preparation device and a liquid ammonia storage tank need to be prepared.
According to the technical scheme, urea particles can be prepared into urea solution with the concentration of about 40% by adopting urea solution, the urea solution is diluted into urea solution with the concentration of 10% -15% by a dilution metering and distributing system, and the urea solution is sprayed into a flue through uniformly arranged spray guns to fully react with nitrogen oxides in flue gas for denitration. When the urea solution is used as a reducing agent, the urea solution can also be directly purchased or prepared on site.
In the technical scheme, the spray guns 10 are uniformly distributed in the transition flue at intervals of 2-10, so that the flue gas and the reducing agent can be fully mixed. The spray gun 10 adopts a double-fluid spray gun and is provided with cooling air; the spray gun interface is divided into a solution interface, a compressed air interface and a cooling air interface, and the spray gun material body and the spray nozzle are made of 310S materials and are high-temperature resistant and wear resistant. An anti-abrasion sleeve or an anti-abrasion coating is arranged at the nozzle of the spray gun. The angle of the spray gun nozzle can be 20-90 degrees according to the actual situation.
In the technical scheme, the SNCR denitration injection system 2 can remove most of nitrogen oxides in high-temperature flue gas, so that after a main exhaust fan of the dust remover, an oxidation denitration system 8 is arranged at the inlet section of a wet desulfurization or alkali liquor tower of the main exhaust fan, the oxidation denitration system 8 adopts ozone denitration or hydrogen peroxide oxidation denitration to further remove the nitrogen oxides in the flue gas, and the ultralow emission is less than or equal to 50mg/Nm3The concentration of nitrogen oxides.
In the above technical scheme, the oxidation denitration system 8 is provided with the ozone injection device 11, the ozone injection device 11 adopts the injection grid form, guarantees the distribution uniformity, and combines the rear end static mixer. The hydrogen peroxide spray gun is a porous spray gun and is uniformly arranged in the flue, and the flue is anticorrosive by coating glass flakes inside or is made of 316L materials.
In the technical scheme, the temperature of the flue gas is reduced from 1150-1110 ℃ to 420-480 ℃ through the preheating section of the chain grate, the flue gas is conveyed to the first drying section through the fan, the temperature is reduced from 260-350 ℃ to 60-180 ℃, the flue gas is mixed with 230-300 ℃ hot air of the second drying section of the chain grate, and finally the mixed flue gas with the temperature lower than 170 ℃ is formed through convergence. The temperature of the flue gas entering the electrostatic dust collector 6 is less than 170 ℃; the temperature of flue gas entering the oxidation and denitration system 8 is 150-200 ℃; the temperature of the flue gas entering the desulfurizing tower 9 is less than 150 ℃.
Example 1 flue gas volume of calcination tail gas of certain ferronickel manufacturer 375000m3The temperature of the original flue gas is 200-400 ℃, and the parameters and system selection of other pollutants are shown in the following table 1:
table 1: smoke parameter table
The flue gas discharged after being treated by the coupling method for removing nitric oxide from the tail gas of the chain grate-rotary kiln reaches the following technical indexes as shown in table 2:
TABLE 2
| Serial number | Index item | Unit of | Index value | Remarks for note |
| 1 | Final emission NOx concentration | mg/Nm3 | 45 | Standard condition, wet basis, actual oxygen |
Therefore, the coupling method for removing nitrogen oxide in tail gas of the chain grate-rotary kiln is used for carrying out oxidation denitration on the nitrogen oxide escaping from low-temperature flue gas by adopting the oxidation denitration system after the nitrogen oxide in the front-end high-temperature flue gas is reduced and removed by the SNCR denitration injection system, removing the escaping nitrogen oxide, oxidizing the escaping nitrogen oxide into high-valence nitrogen oxide, absorbing the high-valence nitrogen oxide by the rear-end alkali liquor to form nitrate, and then recycling the nitrate together with gypsum, so that the ultralow emission is less than or equal to 50mg/Nm3The concentration of nitrogen oxides.
The above description is only for the specific embodiments of the present invention, and it should be noted that the remaining detailed descriptions are related to the prior art, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the protection scope of the present invention.
Claims (10)
1. A coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln is characterized by comprising the following steps: the method comprises the following steps: high-temperature flue gas discharged from the rotary kiln (1) enters an SNCR denitration injection system (2), and SNCR non-selective reduction reaction is carried out in the SNCR denitration injection system (2) to remove partial nitrogen oxides; then the flue gas passes through drying grate preheating section (3), drying grate II section (4), drying grate I section (5), electrostatic precipitator (6), main exhaust fan (7), oxidation deNOx systems (8) in proper order, and NO in the flue gas is oxidized into NO in oxidation deNOx systems (8)2Finally, the flue gas passes through a desulfurizing tower (9), and NO in the flue gas2Absorbed by the alkaline solution in the desulfurizing tower to realize the removal and purification of nitrogen oxides.
2. The coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln as claimed in claim 1, characterized in that: the SNCR denitration injection system (2) is arranged in a transition flue between the tail section of the rotary kiln (1) and the preheating section (3) of the chain grate machine.
3. The coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln as claimed in claim 1, characterized in that: the SNCR denitration injection system (2) is provided with a plurality of spray guns (10) for injecting reducing agents, and the reducing agents adopt one of ammonia water and urea solution.
4. The coupling method for removing nitrogen oxides in tail gas of a chain grate-rotary kiln as claimed in claim 3, characterized in that: spraying the reducing agent into a region with the temperature of 850-1150 ℃, and quickly thermally decomposing the reducing agent to obtain NH3Under the action of no catalyst, the NOx in the high-temperature flue gas is subjected to SNCR reaction to generate N2。
5. The coupling method for removing nitrogen oxides in tail gas of a chain grate-rotary kiln as claimed in claim 3, characterized in that: the dilution concentration of the ammonia water is 10-15%, and the dilution concentration of the urea solution is 10-15%.
6. The coupling method for removing nitrogen oxides in tail gas of a chain grate-rotary kiln as claimed in claim 3, characterized in that: 2-10 spray guns (10) are uniformly distributed in the transition flue at intervals, and the spray guns (10) adopt double-fluid spray guns and are provided with cooling air; the nozzle angle of the spray gun (10) is 20-90 degrees.
7. The coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln as claimed in claim 1, characterized in that: and the oxidation denitration system (8) adopts ozone denitration or hydrogen peroxide oxidation denitration.
8. The coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln as claimed in claim 1, characterized in that: the oxidation denitration system (8) is provided with an ozone injection device (11), and the ozone injection device (11) adopts an injection grid form.
9. The coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln as claimed in claim 1, characterized in that: the temperature of the flue gas is reduced from 1150-1110 ℃ to 420-480 ℃ through the preheating section (3) of the chain grate, the flue gas is conveyed to the drying section I (5) through the fan, the temperature is reduced from 260-350 ℃ to 60-180 ℃, the flue gas is mixed with the hot air at 230-300 ℃ of the drying section II (4) of the chain grate, and finally the mixed flue gas with the temperature less than 170 ℃ is formed through convergence.
10. The coupling method for removing nitrogen oxides from tail gas of a chain grate-rotary kiln as claimed in claim 1, characterized in that: the temperature of the flue gas entering the electrostatic dust collector (6) is less than 170 ℃; the temperature of flue gas entering the oxidation denitration system (8) is 150-200 ℃; the temperature of the flue gas entering the desulfurizing tower (9) is less than 150 ℃.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112833413A (en) * | 2021-02-22 | 2021-05-25 | 山东金岭矿业股份有限公司 | Optimized grate-rotary kiln SCR denitration system and denitration process thereof |
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| JP2002136837A (en) * | 2000-11-01 | 2002-05-14 | Taiheiyo Cement Corp | Non-catalytic denitration method |
| CN109794146A (en) * | 2019-03-28 | 2019-05-24 | 中冶南方都市环保工程技术股份有限公司 | A kind of grate kiln SNCR/SCR denitration and active coke desulphurizing combined system and technique |
| CN111167275A (en) * | 2020-01-19 | 2020-05-19 | 铜陵有色金属集团股份有限公司 | Combined denitration device and process for chain grate-rotary kiln pellet production system |
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- 2020-11-19 CN CN202011302178.3A patent/CN112604473A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002136837A (en) * | 2000-11-01 | 2002-05-14 | Taiheiyo Cement Corp | Non-catalytic denitration method |
| CN109794146A (en) * | 2019-03-28 | 2019-05-24 | 中冶南方都市环保工程技术股份有限公司 | A kind of grate kiln SNCR/SCR denitration and active coke desulphurizing combined system and technique |
| CN111167275A (en) * | 2020-01-19 | 2020-05-19 | 铜陵有色金属集团股份有限公司 | Combined denitration device and process for chain grate-rotary kiln pellet production system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112833413A (en) * | 2021-02-22 | 2021-05-25 | 山东金岭矿业股份有限公司 | Optimized grate-rotary kiln SCR denitration system and denitration process thereof |
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