CN116059810A - Method for removing sulfur trioxide in flue gas and flue gas treatment process method - Google Patents
Method for removing sulfur trioxide in flue gas and flue gas treatment process method Download PDFInfo
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 153
- 239000003546 flue gas Substances 0.000 title claims abstract description 153
- 238000000034 method Methods 0.000 title claims abstract description 75
- 230000008569 process Effects 0.000 title claims abstract description 31
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 title claims abstract description 16
- 239000003513 alkali Substances 0.000 claims abstract description 85
- 239000002245 particle Substances 0.000 claims abstract description 50
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 43
- 239000007921 spray Substances 0.000 claims abstract description 33
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 27
- 230000023556 desulfurization Effects 0.000 claims abstract description 27
- 238000010791 quenching Methods 0.000 claims abstract description 24
- 230000000171 quenching effect Effects 0.000 claims abstract description 23
- 230000008859 change Effects 0.000 claims abstract description 14
- 239000012670 alkaline solution Substances 0.000 claims abstract description 10
- 230000007704 transition Effects 0.000 claims abstract description 10
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 42
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 21
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 18
- 238000005507 spraying Methods 0.000 claims description 18
- 239000000243 solution Substances 0.000 claims description 15
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 10
- BNOODXBBXFZASF-UHFFFAOYSA-N [Na].[S] Chemical compound [Na].[S] BNOODXBBXFZASF-UHFFFAOYSA-N 0.000 claims description 10
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 claims description 9
- 229910000342 sodium bisulfate Inorganic materials 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 8
- 239000002131 composite material Substances 0.000 claims description 8
- 239000003054 catalyst Substances 0.000 claims description 7
- 230000003009 desulfurizing effect Effects 0.000 claims description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 2
- 239000003517 fume Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 24
- 239000002585 base Substances 0.000 abstract description 23
- 239000007789 gas Substances 0.000 abstract description 6
- 238000005345 coagulation Methods 0.000 abstract description 5
- 230000015271 coagulation Effects 0.000 abstract description 5
- 230000007480 spreading Effects 0.000 abstract description 3
- 238000003892 spreading Methods 0.000 abstract description 3
- 238000005728 strengthening Methods 0.000 abstract description 3
- 239000000428 dust Substances 0.000 description 23
- 238000005516 engineering process Methods 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 239000003795 chemical substances by application Substances 0.000 description 10
- 238000009833 condensation Methods 0.000 description 9
- 230000005494 condensation Effects 0.000 description 9
- 239000010419 fine particle Substances 0.000 description 8
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000007547 defect Effects 0.000 description 4
- 239000008187 granular material Substances 0.000 description 4
- 239000000779 smoke Substances 0.000 description 4
- 239000000443 aerosol Substances 0.000 description 3
- 238000005054 agglomeration Methods 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 3
- 239000013618 particulate matter Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000002309 gasification Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 239000006096 absorbing agent Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012717 electrostatic precipitator Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000007726 management method Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000001089 thermophoresis Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 230000002087 whitening 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
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
- F23J15/04—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material using washing fluids
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/30—Alkali metal compounds
- B01D2251/304—Alkali metal compounds of sodium
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
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- Environmental & Geological Engineering (AREA)
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- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
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Abstract
The invention discloses a method for removing sulfur trioxide in flue gas and a flue gas treatment process method, wherein in a first neutralization section, flue gas with the temperature not lower than 250 ℃ is in spray contact with a first alkali liquor to remove SO 3 The method comprises the steps of carrying out a first treatment on the surface of the In the second neutralization section, the flue gas is in spray contact with a second alkaline solution to remove SO 3 The method comprises the steps of carrying out a first treatment on the surface of the In the quenching phase transition section, the SO is removed for the second time 3 Quenching the flue gas to 30-10 ℃ to cool SO in the flue gas 3 And carrying out third removal on the particles. The flue gas treatment process method sequentially comprises a first neutralization section, a denitration section, a second neutralization section, a spray desulfurization section, a quenching phase change section and a demisting section. The method adopts three steps to remove SO in the flue gas 3 By using high-temperature flue gas and spray alkaliLiquid contact instantaneously forms base particles and reacts with SO 3 Reaction, naHCO in partial base particles at high temperature 3 Decomposing to form gas and spreading from inside to outside to form porous base particles for strengthening SO 3 The reaction inside the base particles and the phase change coagulation section further improve the removal rate.
Description
Technical Field
The invention relates to a method for removing sulfur trioxide in flue gas, in particular to a method for removing SO from flue gas by alkali neutralization and humidification phase change 3 A method and a flue gas treatment process method.
Background
The boiler flue gas and the flue gas discharged by factories contain sulfur dioxide and dust, the sulfur dioxide and the dust are main component dust of atmospheric pollutants, the sulfur dioxide is a main reason for forming acid rain, and the dust with smaller particle size is one of the main causes of haze formation.
The wet desulfurization has the advantages of high desulfurization rate, reliable running of the device, simple operation and the like, so that the existing flue gas desulfurization technology in various countries in the world mainly comprises wet desulfurization. The traditional wet desulfurization technology mainly comprises a limestone-gypsum method, a double-alkali desulfurization method, a sodium-alkali desulfurization method, an ammonia desulfurization method and the like. The flue gas desulfurization technology mainly adopts countercurrent spraying, alkaline slurry is sprayed from the upper part of a desulfurization tower, and free sedimentation and countercurrent contact with flue gas are carried out under the action of gravity to realize desulfurization reaction.
The particle size of dust in the flue gas is smaller, most of the dust is between 0.1 and 200 mu m, and the current flue gas dust removal technology mainly comprises a cloth bag type dust removal technology, an electrostatic dust removal technology and a wet dust removal technology. Because the flue gas contains moisture, dust is absorbed and bonded on the filter bag of the bag-type dust collector to block the pores of the filter bag, so that the filter bag needs to be cleaned or replaced frequently, and the application of the bag-type dust collector is greatly limited; the main defects of the electrostatic precipitator are high cost, strict installation, maintenance and management requirements, high-voltage power transformation and rectification control equipment, high power consumption and large occupied area; the wet dust removal technology mainly removes dust carried in the flue gas through spray water, and liquid drops with smaller particle sizes still can be discharged out of a chimney along with the flue gas after being combined with the dust.
2015, 12 months 11The national environmental protection department, the national development and reform committee, the national energy agency, jointly issue a working scheme for comprehensively implementing ultra-low emission and energy conservation transformation of coal-fired power plants (around [2015 ]]164), the proposal prescribes that all coal-fired power plants with transformation conditions strive to realize ultra-clean emission in the country by 2020, namely under the condition of the standard oxygen content of 6 percent, the flue gas dust is not more than 10mg/Nm3, SO 2 No more than 35mg/Nm3. The existing wet desulphurization device is difficult to meet the requirements of emission standards.
Along with the large-scale popularization and application of the wet desulfurization technology in China, one obvious and difficult-to-overcome defect of the wet desulfurization technology is gradually revealed, the defect is that the discharged flue gas can generate a white smoke phenomenon at a chimney mouth, even a white smoke long dragon of a plurality of kilometers can be formed, strong visual impact is brought to people, and a dust and rain phenomenon can occur on the ground sometimes. Therefore, how to eliminate the phenomenon of "white smoke" is a problem to be solved at present.
When containing gaseous SO 3 When the flue gas passes through the wet flue gas desulfurization system, the flue gas is rapidly cooled to be below the acid dew point SO 3 Submicron H which is difficult to trap is rapidly formed through homogeneous nucleation and heterogeneous nucleation with particulate matters as condensation nuclei 2 SO 4 An aerosol. In general, larger droplets of particles in the flue gas are removable by the absorber, but for submicron levels of H 2 SO 4 Aerosol, absorption tower is unable to form H 2 SO 4 Submicron aerosol can only be discharged into the atmosphere through a chimney, and a blue smoke phenomenon is formed at the chimney opening.
Chinese patent CN201620978839.7 proposes a system suitable for phase-change agglomeration of wet desulfurization device to cooperatively remove fine particles, which utilizes the characteristic of high flue gas humidity in wet flue gas desulfurization device, and makes fine particles approach to cold wall under the thermophoresis force generated by temperature gradient under the cooling of circulating cooling water in phase-change agglomeration device, so as to enhance collision between fine particles and liquid drop/liquid film. And the cooling water enables the water vapor to grow up by taking the fine particles as condensation nuclei, so that the agglomeration growth and removal of the fine particles are realized.
Chinese patent CN201620257231.5 integrates deep purification charged dust removal technology and phase change coagulation technology, and combines fine particulate matter coagulation and large particulate matter charge removal to improve particulate matter removal effect of the system.
Chinese patent CN201510587296.6 provides a method for condensing supersaturated water gas on the surface of fine particles by utilizing the principle of composite phase-change condensation, so as to promote the collision and condensation of dust-containing droplets, so that the particle size of fine particles in flue gas is increased, and the trapping efficiency of the desulfurizing tower on the fine particles is improved. The vortex phase-change device is arranged in the flue gas inlet pipeline to enable the flue gas to be cooled, phase-change is carried out, rotational flow is generated, and the purposes of phase-change condensation, coalescence and removal are achieved.
Chinese patent CN201920683029.2 provides a flue gas terminal dehydration and whitening device based on phase change, in which a vertical heat pipe is arranged in the phase change cooling zone of the device, the evaporation section of the heat pipe is located in the dust removal box, and the condensation section of the heat pipe is located outside the dust removal box. The purpose of cooling the flue gas is achieved by using a heat pipe technology.
However, the prior art method has SO 3 Low removal rate.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for removing sulfur trioxide in flue gas, which adopts the combination of alkali neutralization and humidification phase change to remove SO 3 And provides a process method for flue gas treatment comprising the process.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
the technical aim of the first aspect of the invention is to provide a method for removing sulfur trioxide in flue gas, which comprises a first neutralization section, a second neutralization section and a quenching phase change section, wherein in the first neutralization section, flue gas with the temperature of not lower than 250 ℃ is in first contact with first alkali liquor spray formed by first alkali liquor, SO that SO in the flue gas is removed 3 Carrying out first removal; in the second neutralization stage, the first SO will be performed 3 The removed flue gas is subjected to second contact with second alkali solution spray formed by the second alkali solution, SO that SO in the flue gas is treated 3 Carrying out secondary removal; in the quenching phase transition section, the second time is removedSO 3 Quenching the flue gas to 30-10 ℃ to cool SO in the flue gas 3 And carrying out third removal on the particles.
Further, the temperature of the flue gas entering the first neutralization section is preferably not lower than 300 ℃.
Furthermore, an atomizing nozzle is used for forming first alkali liquor spray and second alkali liquor spray, and the particle size of formed liquid drops is 10-100 mu m.
Further, the flue gas is counter-currently contacted with the first alkali spray and the second alkali spray.
Further, the solute of the first alkali liquor and the second alkali liquor is sodium bicarbonate or a composite alkali liquor formed by the sodium bicarbonate and at least one selected from sodium bicarbonate and sodium bisulfate. The sodium bicarbonate accounts for 30% -40% of the total weight of the solute in the composite alkali liquor.
Further, the mass concentration of the solute in the first alkali liquor is 20-30%. By SO in the flue gas 3 And (3) spraying the first alkali liquor to contact the high-temperature flue gas according to the sodium-sulfur ratio of 1:1-2:1.
Further, the mass concentration of the solute in the second alkali liquor is 10-20% SO as to perform the first SO 3 SO in the flue gas after removal 3 And (3) enabling the second alkaline solution to be sprayed and contacted with the flue gas according to the sodium-sulfur ratio of 2:1-3:1.
Furthermore, the quenching phase transition section adopts a phase transition condenser to quench the flue gas.
In the method for removing sulfur trioxide in the flue gas, on the one hand, the high-temperature flue gas can be more fully and efficiently contacted with alkali liquor in a spray form in the first neutralization section, the reaction is enhanced, and the SO is enhanced 3 Is removed; on the other hand, under the action of high-temperature flue gas at the temperature of not lower than 250 ℃, water in alkali liquor spray is gasified instantaneously, solute in alkali liquor is crystallized to form base particles, and the base particles and SO are simultaneously mixed 3 The reaction, at this time, due to the high temperature, of NaHCO in part of the base particles 3 Is decomposed to form gas CO 2 And H 2 O, during the process of spreading the gas from inside to outside, the particles form pore channels communicated with each other to form porous base particles, thereby further strengthening SO 3 Inverse within the base particleShould be. In the second neutralization section, the instantaneous gasification of water in alkali liquor spraying also occurs, and the solute in the alkali liquor is crystallized to form base particles, SO in flue gas 3 Carrying out secondary removal; and meanwhile, the surface of the porous base particles formed in the first neutralization section is wetted by spraying, so that the gas-solid reaction on the surface of the alkaline agent particles is converted into gas-liquid reaction, and the reaction activity is enhanced. In the quenching phase transition section, taking alkaline agent particles as cores, and residual SO in the flue gas 3 Phase change coagulation occurs, and the particles attached to the surfaces of the alkaline agent particles are removed, so that the removal rate is further improved.
The technical purpose of the second aspect of the invention is to provide a flue gas treatment process which sequentially comprises a first neutralization section, a denitration section, a second neutralization section, a spray desulfurization section, a quenching phase change section and a demisting section, and the specific process is as follows:
(1) First neutralization section: spraying a first alkali solution formed by high-temperature flue gas with the temperature not lower than 300 ℃ and the first alkali solution to perform first contact on SO in the flue gas 3 Carrying out first removal;
(2) Denitration section: the flue gas treated by the first neutralization section enters a denitration section, and the flue gas is subjected to denitration under the action of an SCR catalyst;
(3) Second neutralization section: the flue gas after denitration enters a second neutralization section and is in second contact with second alkali liquid spray formed by second alkali liquid, SO that SO in the flue gas is treated 3 Carrying out secondary removal;
(4) Spraying desulfurization section: wet desulfurizing SO in fume 2 Removing;
(5) Quenching phase transition section: quenching the flue gas to 30-10 ℃ and quenching SO in the flue gas 3 Removing particles;
(6) Demisting section: and demisting and dedusting the flue gas, and discharging after reaching the discharge standard.
In the above process method of the invention, the flue gas is subjected to the first SO through the first neutralization section 3 Removing, spraying first alkali liquor with higher concentration to perform SO 3 Is removed without causing side effects to the SCR catalyst. Flue gas enters a second neutralization section for second SO after denitration by the SCR reactor 3 Is removed. At this time adoptThe second alkaline solution with lower concentration can be sprayed to properly increase the water content in the flue gas, so that the surfaces of alkaline agent particles formed in the first neutralization section are wetted. The original gas-solid reaction on the surface of the alkaline agent particles is converted into gas-liquid reaction, SO that SO is enhanced 3 Absorption effect. SO is removed by the second neutralization section 3 Then the flue gas enters a wet desulphurization device to carry out SO 2 Is removed. At the moment, the redundant alkaline agent particles carried in the flue gas can be dissolved in the circulating slurry of wet desulfurization, which is favorable for maintaining the pH value of the circulating slurry and is favorable for SO 2 Is removed.
Further, the particle size of the liquid drops in the first alkali liquid spray and the second alkali liquid spray is 10-100 mu m.
Further, the solute of the first alkali liquor and the second alkali liquor is sodium bicarbonate or a composite alkali liquor formed by the sodium bicarbonate and at least one selected from sodium bicarbonate and sodium bisulfate. The sodium bicarbonate accounts for 30% -40% of the total weight of the solute in the composite alkali liquor.
Further, the mass concentration of the solute in the first alkali liquor is 20-30%. By SO in high-temperature flue gas 3 And (3) spraying the first alkali liquor to contact the flue gas according to the sodium-sulfur ratio of 1:1-2:1.
Further, the solute of the second alkali liquor is at least one selected from sodium carbonate, sodium bicarbonate and sodium bisulfate.
Further, the mass concentration of the solute in the second alkali liquor is 10-20% SO as to perform the first SO 3 SO in the flue gas after removal 3 And (3) enabling the second alkaline solution to be sprayed and contacted with the flue gas according to the sodium-sulfur ratio of 2:1-3:1.
Compared with the prior art, the invention has the following advantages:
(1) The method adopts three steps to remove SO in the flue gas 3 Compared with the prior art, in the first neutralization section, on one hand, the high-temperature flue gas can be more fully and efficiently contacted with alkali liquor in a spray form, the reaction is enhanced, and the SO is enhanced 3 Is removed; on the other hand, under the action of high-temperature flue gas at the temperature of not lower than 250 ℃, water in alkali liquor spray is gasified instantaneously, solute in alkali liquor is crystallized to form base particles, and the base particles and SO are simultaneously mixed 3 Reaction of thisAt the time, due to the high temperature, naHCO in part of the base particles 3 Is decomposed to form gas CO 2 And H 2 O, during the process of spreading the gas from inside to outside, the particles form pore channels communicated with each other to form porous base particles, thereby further strengthening SO 3 Reactions within the base particles. In the second neutralization section, the instantaneous gasification of water in alkali liquor spraying also occurs, and the solute in the alkali liquor is crystallized to form base particles, SO in flue gas 3 Carrying out secondary removal; and meanwhile, the surface of the porous base particles formed in the first neutralization section is wetted by spraying, so that the gas-solid reaction on the surface of the alkaline agent particles is converted into gas-liquid reaction, and the reaction activity is enhanced. In the quenching phase transition section, taking alkaline agent particles as cores, and residual SO in the flue gas 3 Phase change coagulation occurs, and the particles attached to the surfaces of the alkaline agent particles are removed, so that the removal rate is further improved.
(2) The flue gas treatment process combines SO in the flue gas 3 The denitration process and the spray desulfurization process are respectively arranged between the first neutralization section and the second neutralization section and between the second neutralization section and the quenching phase change section, the composition characteristics of the flue gas in each stage are fully considered, the design is more scientific and reasonable, and a flue gas treatment process is provided for the prior art.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
Fig. 1 is a schematic diagram of a flue gas treatment process in an embodiment.
In the figure: 1. the flue gas to be purified comprises 2 parts of a first alkali liquor nozzle, 3 parts of a second alkali liquor nozzle, 4 parts of a first denitration catalyst bed layer, 5 parts of a second denitration catalyst, 6 parts of a desulfurizing tower, 7 parts of a first desulfurizing spraying device, 8 parts of a first desulfurizing spraying device, 9 parts of a phase-change condenser, 10 parts of a cooling coil, 11 parts of a demister, 12 parts of a chimney.
Detailed Description
The following non-limiting examples will enable those of ordinary skill in the art to more fully understand the invention and are not intended to limit the invention in any way.
Example 1
A certain flue gas from a factory, SO in the flue gas 3 The content is 45mg/m 3 The first alkali liquor is a composite solution formed by sodium carbonate, sodium bicarbonate and sodium bisulfate, the mass concentration of the solute is 20%, and the mass ratio of the three solutes is 1:1:1. The second alkali liquor is a composite solution formed by sodium carbonate, sodium bicarbonate and sodium bisulfate, the mass concentration of solutes is 10%, and the mass ratio of the three solutes is 1:1:1. And respectively forming first alkali liquor spray and second alkali liquor spray with liquid drops of about 50 mu m by using an atomizing nozzle.
SO is carried out on the flue gas 3 And (3) removing:
(1) First neutralization section: the initial temperature of the flue gas is 310 ℃ and the SO in the flue gas is used 3 Firstly, spraying and countercurrent contacting the flue gas with a first alkali liquor according to a sodium-sulfur ratio of 1:1, instantly gasifying water in the alkali liquor under the action of high-temperature flue gas, forming base particles by solute in the alkali liquor, and simultaneously forming part of NaHCO (NaHCO) 3 Is decomposed to form CO 2 And H 2 O，CO 2 And H 2 The O can make the base particles form a large number of holes in the process of diffusing to the outside of the particles, so as to strengthen the gas-solid reaction.
(2) Second neutralization section: (1) The treated flue gas is in countercurrent contact with second alkali solution spray again according to the sodium-sulfur ratio of 2:1, and the water in the alkali solution is gasified instantly under the action of high-temperature flue gas to form base particles, and part of NaHCO is simultaneously carried out 3 Is decomposed to form CO 2 And H 2 O。CO 2 And H 2 O makes alkaline agent granule form a large amount of channels in the in-process of diffusing to granule outside, strengthens gas-solid reaction, and the spraying can wet the surface of the porous base granule that forms upstream simultaneously, makes base granule surface take place gas-solid reaction and converts gas-liquid reaction, improves reaction rate.
(3) Quenching phase transition section: quenching the flue gas treated in the step (2), and cooling to 30 ℃ to obtain water vapor and SO in the flue gas 3 Taking the particles as condensation nuclei to carry out heterogeneous condensation, and further removing the particles.
Through the above processes, SO in the flue gas is finally obtained 3 The removal rate is 98%.
Comparative example 1
The procedure is as in example 1, except that step (2) is not carried out, and SO in the final flue gas 3 The removal rate is 90%.
Comparative example 2
The procedure is as in example 1, except that step (3) is not performed, and SO in the final flue gas 3 The removal rate is 90%.
Example 2
To be treated is another flue gas from a factory, SO in the flue gas 3 The content is 20mg/m 3 The content is low.
The treatment process is the same as in example 1, and SO in the final flue gas 3 The removal rate is 99%.
Comparative example 3
The procedure is as in example 2, except that step (2) is not carried out, and SO in the final flue gas 3 The removal rate is 93%.
Comparative example 4
The procedure is as in example 2, except that step (3) is not carried out, and SO in the final flue gas 3 The removal rate is 95%.
Example 3
To be treated is another flue gas from a factory, SO in the flue gas 3 The content is 90mg/m 3 The content is higher.
The treatment process is the same as in example 1, and SO in the final flue gas 3 The removal rate is 95%.
Comparative example 5
The procedure is as in example 3, except that step (2) is not carried out, and SO in the final flue gas 3 The removal rate is 65%.
Comparative example 6
The procedure is as in example 3, except that step (3) is not performed, and SO in the final flue gas 3 The removal rate is 75%.
Example 4
The procedure of example 3 was followed except that the mass ratio of solute sodium carbonate, sodium bicarbonate and sodium bisulfate in the primary alkali solution and the secondary alkali solution was 1:2:1. Finally SO in flue gas 3 The removal rate is 95%.
Example 5
The embodiment discloses a flue gas treatment process, wherein the composition of a first alkali liquor and a second alkali liquor is the same as that of embodiment 1.
SO in flue gas 3 The content is 40mg/m 3 ，SO 2 The content is 400mg/m 3 ，NO X The content of the extract is 350mg/m 3 The flue gas temperature is 320 ℃, and the flue gas volume is 120000Nm 3 The process is carried out by the process system shown in fig. 1 as follows:
the flue gas 1 to be purified at 320 ℃ is firstly in countercurrent contact with the primary alkali liquor sprayed from the primary alkali liquor nozzle 2 for reaction, SO as to carry out 3 After that, the flue gas temperature is about 320 ℃, flue gas denitration is carried out through a first denitration catalyst bed layer 4 and a second denitration catalyst bed layer 5 in sequence, the bed reaction temperature is 310 ℃, and the flue gas after denitration and a second alkaline solution sprayed by a second alkaline solution nozzle 3 are in contact reaction to carry out SO 3 Finally enters a desulfurization tower 6, is internally provided with a first desulfurization spray device 7 and a second desulfurization spray device 8, adopts the traditional nano-method desulfurization to remove SO 2 Then enters a phase-change condenser 9, the flue gas is quenched to below 30 ℃ under the action of a cooling coil 10, and the residual SO in the flue gas 3 Phase-change condensation is carried out by taking particles as cores with water vapor, SO that SO is further removed 3 Then enters a demister 11, removes dust and demists, and is discharged from a chimney 12.
After the measurement and the treatment by the process, SO in the flue gas 3 The removal rate is 90%, SO 2 The removal rate is 95%, NO X The removal rate is 95%.
Claims (14)
1. A method for removing sulfur trioxide in flue gas comprises a first neutralization section, a second neutralization section and a quenching phase change section, wherein in the first neutralization section, flue gas with the temperature of not lower than 250 ℃ is sprayed with a first alkali liquor formed by the first alkali liquor for first contact, and SO in the flue gas is sprayed with the first alkali liquor 3 Carrying out first removal; in the second neutralization stage, the first SO will be performed 3 The removed flue gas is subjected to second contact with second alkali solution spray formed by the second alkali solution, SO that SO in the flue gas is treated 3 Carrying out secondary removal; in the quenching phase transition section, the SO is removed for the second time 3 Quenching the flue gas to 30-10 ℃ to cool SO in the flue gas 3 ParticlesThe material was removed a third time.
2. The method of claim 1, wherein the temperature of the flue gas entering the first neutralization stage is no less than 300 ℃.
3. The method according to claim 1, wherein the droplets in the first alkali liquid spray and the second alkali liquid spray have a particle size of 10 to 100 μm.
4. The method of claim 1, wherein the flue gas is countercurrently contacted with the primary alkali spray and the secondary alkali spray.
5. The method according to claim 1, wherein the solute of the primary alkali and the secondary alkali is sodium bicarbonate or a complex alkali formed by sodium bicarbonate and at least one selected from sodium bicarbonate and sodium bisulfate.
6. The method according to claim 1, wherein the sodium bicarbonate comprises 30% -40% by weight of the total weight of solutes in the complex lye.
7. The method according to claim 1, wherein the mass concentration of the solute in the primary alkali solution is 20-30% by mass of SO in the flue gas 3 And (3) spraying the first alkali liquor to contact the high-temperature flue gas according to the sodium-sulfur ratio of 1:1-2:1.
8. The method according to claim 1, wherein the solute in the second lye is present in a concentration of 10-20% by mass for the first SO 3 SO in the flue gas after removal 3 And (3) enabling the second alkaline solution to be sprayed and contacted with the flue gas according to the sodium-sulfur ratio of 2:1-3:1.
9. The technical method for flue gas treatment sequentially comprises a first neutralization section, a denitration section, a second neutralization section, a spray desulfurization section, a quenching phase change section and a demisting section, and comprises the following specific processes:
(1) First neutralization section: spraying a first alkali solution formed by high-temperature flue gas with the temperature not lower than 300 ℃ and the first alkali solution to perform first contact on SO in the flue gas 3 Carrying out first removal;
(2) Denitration section: the flue gas treated by the first neutralization section enters a denitration section, and the flue gas is subjected to denitration under the action of an SCR catalyst;
(3) Second neutralization section: the flue gas after denitration enters a second neutralization section and is in second contact with second alkali liquid spray formed by second alkali liquid, SO that SO in the flue gas is treated 3 Carrying out secondary removal;
(4) Spraying desulfurization section: wet desulfurizing SO in fume 2 Removing;
(5) Quenching phase transition section: quenching the flue gas to 30-10 ℃ and quenching SO in the flue gas 3 Removing particles;
(6) Demisting section: and demisting and dedusting the flue gas, and discharging after reaching the discharge standard.
10. The process according to claim 9, wherein the droplets in the first and second alkali sprays have a particle size of 10 to 100 μm.
11. The process according to claim 9, wherein the solute of the primary alkali is sodium bicarbonate or a complex alkali formed by sodium bicarbonate and at least one selected from sodium bicarbonate and sodium bisulfate; the sodium bicarbonate accounts for 30% -40% of the total weight of the solute in the composite alkali liquor.
12. The process according to claim 9, wherein the mass concentration of the solute in the first alkaline solution is 20-30%; by SO in high-temperature flue gas 3 And (3) spraying the first alkali liquor to contact the flue gas according to the sodium-sulfur ratio of 1:1-2:1.
13. The process according to claim 9, wherein the solute of the secondary lye is selected from at least one of sodium carbonate, sodium bicarbonate and sodium bisulfate.
14. The process according to claim 9, wherein the solute in the second alkaline solution has a mass concentration of 10-20% for the first SO 3 SO in the flue gas after removal 3 And (3) enabling the second alkaline solution to be sprayed and contacted with the flue gas according to the sodium-sulfur ratio of 2:1-3:1.
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Effective date of registration: 20240129 Address after: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Applicant after: CHINA PETROLEUM & CHEMICAL Corp. Country or region after: China Applicant after: Sinopec (Dalian) Petrochemical Research Institute Co.,Ltd. Address before: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Applicant before: CHINA PETROLEUM & CHEMICAL Corp. Country or region before: China Applicant before: DALIAN RESEARCH INSTITUTE OF PETROLEUM AND PETROCHEMICALS, SINOPEC Corp. |