WO2011016585A1 - 排ガス処理装置及び排ガスの水銀除去方法 - Google Patents
排ガス処理装置及び排ガスの水銀除去方法 Download PDFInfo
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- WO2011016585A1 WO2011016585A1 PCT/JP2010/063673 JP2010063673W WO2011016585A1 WO 2011016585 A1 WO2011016585 A1 WO 2011016585A1 JP 2010063673 W JP2010063673 W JP 2010063673W WO 2011016585 A1 WO2011016585 A1 WO 2011016585A1
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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
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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
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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
- B01D53/64—Heavy metals or compounds thereof, e.g. mercury
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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
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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
- B01D53/8665—Removing heavy metals or compounds thereof, e.g. mercury
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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
- B01D53/90—Injecting reactants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/30—Injector mixers
- B01F25/31—Injector mixers in conduits or tubes through which the main component flows
- B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
- B01F25/3132—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit by using two or more injector devices
- B01F25/31322—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit by using two or more injector devices used simultaneously
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/30—Injector mixers
- B01F25/31—Injector mixers in conduits or tubes through which the main component flows
- B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
- B01F25/3133—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit characterised by the specific design of the injector
- B01F25/31331—Perforated, multi-opening, with a plurality of holes
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- 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
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- 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
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/40—Alkaline earth metal or magnesium compounds
- B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/50—Inorganic acids
- B01D2251/502—Hydrochloric acid
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/606—Carbonates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/608—Sulfates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/60—Heavy metals or heavy metal compounds
- B01D2257/602—Mercury or mercury compounds
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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
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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
- B01D53/68—Halogens or halogen compounds
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/20—Sulfur; Compounds thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/60—Heavy metals; Compounds thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2219/00—Treatment devices
- F23J2219/10—Catalytic reduction devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2219/00—Treatment devices
- F23J2219/40—Sorption with wet devices, e.g. scrubbers
Definitions
- the present invention relates to an exhaust gas treatment apparatus for oxidizing mercury contained in exhaust gas discharged from a boiler or the like and a method for removing mercury from the exhaust gas.
- the exhaust gas generated when burning coal-fired exhaust gas or heavy oil may contain metal mercury (Hg 0 ) in addition to soot, sulfur oxide (SOx), and nitrogen oxide (NOx).
- Hg 0 metal mercury
- SOx sulfur oxide
- NOx nitrogen oxide
- various devices have been devised for a method and apparatus for treating metallic mercury in combination with a denitration apparatus that reduces NOx and a wet desulfurization apparatus that uses an alkaline absorbent as an SOx absorbent.
- an ammonium (NH 3 ) solution is sprayed on the upstream side of a high-temperature denitration device in the flue to reduce and denitrify, and an oxidizing aid such as a hydrochloric acid (HCl) solution is sprayed.
- a system has been proposed in which mercury is oxidized (chlorinated) on a denitration catalyst to form water-soluble mercury chloride, and then mercury is removed by a wet desulfurization apparatus installed on the downstream side (for example, patent literature) 1).
- a hydrochloric acid (HCl) solution is vaporized using a hydrogen chloride (HCl) vaporizer to form hydrogen chloride (HCl) gas, adjusted to a mixed gas containing HCl of a predetermined concentration, and then mixed gas Is dispersed in the flue and sprayed uniformly in an exhaust gas containing mercury (see, for example, Patent Document 2).
- ammonium chloride (NH 4 Cl) is added in the form of powder into the flue on the upstream side of the denitration device, and NH 4 Cl is sublimated by the high-temperature ambient temperature of the exhaust gas, and HCl is added.
- ammonia (NH 3 ) is vaporized and the vaporized HCl gas and NH 3 gas are mixed with the exhaust gas (see, for example, Patent Document 3).
- FIG. 29 shows a schematic diagram of an exhaust gas treatment system for exhaust gas discharged from a boiler.
- NH 4 exhaust gas treatment system 100 for spraying NOx discharged coal from the boiler 101 is supplied as a fuel, a solution of NH 4 Cl 103 to the exhaust gas 102 containing Hg 0 in the flue 104
- a Cl spraying device 105, a reduction denitration device 106 including a denitration catalyst that oxidizes Hg 0 while reducing NOx, and a desulfurization device 107 that removes oxidized HgCl in the exhaust gas 102 are included.
- the NH 4 Cl solution 103 is sprayed from the NH 4 Cl solution tank 108 into the exhaust gas 102 discharged from the boiler 101 by the spray nozzle 109, the NH 4 Cl solution 103 is vaporized, and the NH 3 gas and HCl gas are mixed with the exhaust gas 102. To do. Thereafter, the exhaust gas 102 is supplied to the reductive denitration device 106, and NOx is reduced by the denitration catalyst in the reductive denitration device 106 and Hg 0 is oxidized.
- the exhaust gas 102 after removal of NOx is heat-exchanged with the air 111 by an air preheater (air heater) 110, and after heat recovery, it is supplied to the electrostatic precipitator 112 to remove dust in the exhaust gas 102 after heat recovery. Is done.
- the exhaust gas 102 is supplied to the desulfurization device 107, brought into gas-liquid contact with the gypsum slurry 113 supplied to the desulfurization device 107, SOx and Hg are removed, and exhausted from the chimney 115 as the purified gas 114.
- the NOx concentration in the exhaust gas 102 is measured by the NOx measuring meter 116 installed on the upstream side of the reducing denitration device 106 in the flue 104, and the Hg concentration meter 117 installed on the downstream side of the desulfurizing device 107.
- the concentration of Hg is measured.
- the operation unit 118 calculates the supply amount and concentration of the NH 4 Cl solution 103 supplied from the NH 4 Cl solution tank 108. Supply amount of the calculated solution of NH 4 Cl 103, based on the concentration, to control the supply amount of the solution of NH 4 Cl 103 to be supplied to the flue 104 by the control unit 119.
- the oxidation-reduction potential measuring device 120 installed at the bottom of the desulfurization device 107 measures the oxidation-reduction potential, adjusts the supply amount of the air 121, and prevents mercury oxide from being reduced and released.
- a plurality of spray nozzles 109 are provided along the wall surface of the flue 104, for example, and the number of spray nozzles reduces the installation cost and maintainability. Considering this, a smaller number is desirable, but if it is too small, the NH 4 Cl solution 103 cannot be uniformly sprayed into the flue 104. Therefore, NH 3 and HCl generated from the NH 4 Cl solution 103 cannot be uniformly supplied into the exhaust gas 102, and the NH 3 concentration and HCl concentration in the exhaust gas 102 become non-uniform, resulting in a decrease in denitration performance and mercury oxidation performance. There is a problem that.
- the present invention provides an exhaust gas treatment apparatus capable of uniformly supplying a reducing agent and a mercury chlorinating agent into a flue without uneven concentration, and maintaining mercury removal performance and nitrogen oxide reduction performance. It aims at providing the mercury removal method of waste gas.
- the first invention of the present invention is an exhaust gas treatment apparatus for removing nitrogen oxides and mercury contained in exhaust gas from a boiler, and an oxidizing gas when vaporized in a flue downstream of the boiler And a reduction oxidation auxiliary agent supplying means for spraying a reduction oxidation auxiliary for generating a reducing gas in a liquid state with a plurality of spray nozzles, and reducing the nitrogen oxide in the exhaust gas with the reducing gas, and the oxidation Reductive denitration means having a denitration catalyst that oxidizes mercury in the presence of a reactive gas, and wet desulfurization means for removing mercury oxidized in the reductive denitration means using an alkaline absorbent, the spray nozzle comprising: In the exhaust gas treatment apparatus, the reducing oxidation aid is supplied into the flue so as not to adhere to the inner wall of the flue.
- the second invention is based on at least the gas flow velocity, the initial droplet velocity, the droplet diameter, the exhaust gas temperature, the distance required for droplet vaporization determined from the droplet temperature, and the injection angle ⁇ in the first invention.
- the exhaust nozzle is arranged such that the shortest distance x from the inner wall of the flue to the nozzle hole of the spray nozzle satisfies the following formula. x> l ⁇ sin ⁇ (1)
- a third invention is the exhaust gas treatment apparatus according to the first or second invention, wherein the reducing oxidation assistant is ammonium chloride.
- the fourth invention is the exhaust gas according to any one of the first to third inventions, wherein the nozzle hole of the spray nozzle is provided at a position separated from the wall surface of the flue by 0.5 m or more. In the processing unit.
- a fifth invention is an exhaust gas processing apparatus according to any one of the first to fourth inventions, wherein the plurality of spray nozzles are arranged so as to satisfy the following formula. a ⁇ b / 5 (2) However, a is the distance between the nozzle holes of the spray nozzle, and b is the length of the long side of the length of the cross section of the flue.
- a sixth invention is the exhaust gas treatment apparatus according to any one of the first to fifth inventions, wherein the spray nozzle has a plurality of nozzle holes for spraying the reducing oxidation aid.
- the seventh invention is the exhaust gas treatment apparatus according to the sixth invention, wherein the interval between the nozzle holes is 0.3 m or less.
- the eighth invention is an exhaust gas treatment apparatus according to any one of the first to seventh inventions, wherein the spray amount from each of the spray nozzles can be changed.
- the ninth invention is the ammonia gas according to any one of the first to eighth inventions, which is provided between the reducing oxidation aid supplying means and the reducing denitration means and supplies ammonia gas into the flue.
- the exhaust gas treatment apparatus has one or both of a supply unit and a hydrogen chloride gas supply unit for supplying hydrogen chloride gas into the flue.
- a tenth aspect of the invention is a mercury removal method for exhaust gas that removes nitrogen oxides and mercury contained in the exhaust gas from the boiler, wherein the oxidizing gas and the reducing gas are vaporized into the flue of the boiler.
- a reduction oxidation auxiliary agent supplying step of spraying a reduction oxidation auxiliary agent in a liquid state with a plurality of spray nozzles, reducing nitrogen oxide in the exhaust gas with the reducing gas with a denitration catalyst, and the oxidizing property A reductive denitration process that oxidizes mercury in the presence of a gas; and a wet desulfurization process that removes mercury oxidized in the reductive denitration process using an alkali absorbent, and the spray nozzle includes the reductive oxidation process.
- the auxiliary agent is supplied into the flue so as not to adhere to the inner wall of the flue.
- the eleventh invention is based on at least the distance l required for droplet vaporization determined from the gas flow velocity, the initial droplet velocity, the droplet diameter, the exhaust gas temperature, and the droplet temperature and the injection angle ⁇ in the tenth invention.
- the exhaust gas mercury removing method is characterized in that the spray nozzle is arranged such that the shortest distance x from the inner wall of the flue to the nozzle hole of the spray nozzle satisfies the following formula. x> l ⁇ sin ⁇ (3)
- the twelfth invention is the mercury removal method for exhaust gas according to the tenth or eleventh invention, wherein the reducing oxidation assistant is ammonium chloride.
- a thirteenth aspect of the invention is the exhaust gas mercury according to any one of the tenth to twelfth aspects, wherein the nozzle hole of the spray nozzle is provided at a position separated from the wall surface of the flue by 0.5 m or more. In the removal method.
- a fourteenth invention is an exhaust gas mercury removing method according to any one of the tenth to thirteenth invention, wherein a plurality of spray nozzles are arranged so as to satisfy the following formula. a ⁇ b / 5 (4) However, a is the distance between the nozzle holes of the spray nozzle, and b is the length of the long side of the length of the cross section of the flue.
- the fifteenth invention according to any one of the tenth to fourteenth inventions, further comprising a flow rate measuring step for measuring a flow rate of the exhaust gas upstream of a supply position for supplying the reducing oxidation aid,
- the mercury removal method for exhaust gas is characterized in that the spray amount, spray angle, and initial speed of the reducing oxidation aid are adjusted based on the measured flow rate of the exhaust gas.
- a sixteenth aspect of the invention is the method according to any one of the tenth to fifteenth aspects, wherein a nitrogen oxide concentration measurement step for measuring a concentration of nitrogen oxides in the exhaust gas is provided on a pre-process side of the reduction denitration treatment step.
- a mercury concentration measurement step for measuring the concentration of mercury in the exhaust gas on the downstream side of the reduction denitration treatment step, and the concentration of nitrogen oxide in the exhaust gas obtained by the nitrogen oxide concentration measurement step And the supply amount of the reduction oxidation aid supplied in the reduction oxidation aid supply step based on one or both of the mercury concentration in the exhaust gas obtained by the mercury concentration measurement step
- the seventeenth invention is the ammonia gas supply step of supplying ammonia gas into the flue between the reduction oxidation aid supply step and the reduction denitration treatment step in the fifteenth or sixteenth invention, the smoke
- the ammonia gas supplied from the ammonia gas supply step based on the flow rate of the exhaust gas measured by the flow rate measurement step, including either or both of the hydrogen chloride gas supply step of supplying hydrogen chloride gas in the road,
- the exhaust gas mercury removing method is characterized in that the spray amount, spray angle, and initial velocity of any one or both of the hydrogen chloride gas supplied from the hydrogen chloride gas supply step are adjusted.
- the oxidizing gas and the reducing gas that are generated when the reducing oxidation aid is vaporized are mixed with the exhaust gas at the downstream side of the region where the reducing oxidation aid is vaporized. You may make it provide the mixing means to promote.
- the mixing unit may be formed of a plurality of swirl flow inducing members that generate a swirl flow in the exhaust gas so as to be orthogonal to the flow direction of the exhaust gas.
- the mixing means may be configured such that the unit is provided in a plurality of stages in the flow direction of the exhaust gas.
- the swirl flow inducing member includes a pair of first swirl flow induction plates having opposing surfaces on the exhaust gas inlet side, and a pair of second swirl flow induction plates having opposing surfaces on the exhaust gas discharge side; In the connecting portion that connects the first swirl flow induction plate and the second swirl flow induction plate, both opposing surfaces may be connected to each other.
- the width L and height D of the swirl flow inducing member may be within the range of the following formula.
- B is the length of one side of the cross section of the flue at the installation position
- H is the length of the other side of the cross section of the flue
- MIN (B, H) is one of the cross sections of the flue. Of the side of the flue and the length H of the other side of the cross section of the flue.
- a projecting member may be provided on the inner wall of the flue downstream from the supply position where the flue supplies the reducing oxidation aid into the flue.
- a constriction for narrowing the passage in the flue may be provided on the downstream side of the supply position where the flue supplies the reducing oxidation aid into the flue.
- the spray nozzle may be a two-fluid nozzle that injects the reduction oxidation aid and air for spraying the reduction oxidation aid.
- a flow rate measuring device for measuring the flow rate of the exhaust gas may be provided upstream of the supply position for supplying the reducing oxidation aid.
- the spray nozzle 15 has the following formula (1) according to the spray angle ⁇ of the droplet of the NH 4 Cl solution 14 sprayed from the nozzle hole 15 a of the spray nozzle 15 with respect to the wall surface of the flue 13.
- the droplet sprayed from the spray nozzle 15 can be made not to collide with the wall surface of the flue 13.
- l represents the moving distance until the droplet of the NH 4 Cl solution evaporates.
- the nozzle hole 15a of the spray nozzle 15 is provided at a position separated from the wall surface of the flue 13 by 0.5 m or more, for example.
- the position of the nozzle hole 15a of the spray nozzle 15 is determined based on the gas flow rate of the exhaust gas 12, the initial droplet velocity of the NH 4 Cl solution 14 sprayed from the nozzle hole 15a of the spray nozzle 15, the droplet diameter, and the spray from the spray nozzle 15.
- the droplets of the NH 4 Cl solution 14 to be sprayed are spray nozzles 15.
- the lime gypsum slurry 21 used for the desulfurization stored in the tower bottom 55 of the wet desulfurization apparatus 22 is oxidized and then extracted from the tower bottom 55 and fed to the dehydrator 48. It is discharged out of the system as a dehydrated cake (gypsum) 49 containing HgCl).
- a dehydrated cake (gypsum) 49 containing HgCl) As the dehydrator 48, for example, a belt filter or the like is used. Further, the dehydrated filtrate (dehydrated filtrate) is subjected to wastewater treatment such as removal of suspensions in the dehydrated filtrate, heavy metals, and pH adjustment of the dehydrated filtrate. A part of this drained filtrate is returned to the wet desulfurization device 22, and the other part of the dehydrated filtrate is treated as waste water.
- the lime gypsum slurry 21 is used as the alkali absorbing liquid
- other solutions can be used as the alkali absorbing liquid as long as it can absorb HgCl in the exhaust gas 12.
- the flue 13 is provided with mercury (Hg) concentration meters 54-1 and 54-2 for measuring the Hg content in the exhaust gas 12 discharged from the boiler 11.
- the Hg concentration meter 54-1 is provided in the flue 13 between the boiler 11 and the spray nozzle 15, and the Hg concentration meter 54-2 is provided between the reducing denitration device 18 and the heat exchanger 19.
- the value of the Hg concentration in the exhaust gas 12 measured by the Hg concentration meters 54-1 and 54-2 is transmitted to the control device 52.
- the control device 52 can confirm the content of Hg contained in the exhaust gas 12 from the value of the Hg concentration in the exhaust gas 12 measured by the Hg concentration meters 54-1 and 54-2.
- the oxidation-reduction potential of the lime gypsum slurry 21 in the wet desulfurization apparatus 22 is preferably in the range of 150 mV to 600 mV, for example, in order to prevent re-scattering of Hg from the lime gypsum slurry 21. This is because, if the oxidation-reduction potential is within the above range, Hg collected as HgCl 2 in the lime-gypsum slurry 21 is a stable region, and re-scattering into the atmosphere can be prevented.
- NH 4 Cl is used as a reduction oxidation aid, but ammonium bromide (NH 4 Br) other than NH 4 Cl, ammonium iodide (NH 4 I). ) Or the like may be used as a reduction oxidation aid, and a solution dissolved in water may be used.
- the NH 3 gas and the HCl gas into the exhaust gas 12 are arranged by arranging the plurality of spray nozzles 15 in the flue 13 so as to satisfy the above formula (7). And the variation in the concentration of HCl gas and NH 3 gas in the flue 13 can be reduced, so that the oxidation performance of Hg in the reductive denitration device 18 can be further improved, and NOx The reduction performance can be further improved.
- the spray nozzle 61 is provided with four nozzle holes 15 a for spraying the NH 3 Cl solution 14.
- the amount of the NH 3 Cl solution 14 sprayed from the single spray nozzle 61 into the flue 13 can be increased.
- the mixing of the three gases can be further promoted. For this reason, the reduction performance of Hg and the reduction performance of NOx can be further improved in the reduction denitration apparatus 18.
- the interval c between the nozzle holes 15a is preferably 0.3 m or less.
- the horizontal movement distance of the droplet that is, the shortest distance x from the inner wall 13a of the flue 13 to the nozzle hole 15a of the spray nozzle 15
- the droplets flow in the gas flow direction after evaporation and sublimation, it is desirable that the droplets sprayed from the two nozzle holes 15a overlap before the evaporation and sublimation in order to make the concentration distribution uniform.
- a partial enlarged view of the spray nozzle 61 is shown in FIG. As shown in FIG.
- the droplets ejected from the two nozzle holes 15a can be overlapped by setting the interval c between the nozzle holes 15a to 0.3 m or less.
- the droplet diameter that is actually used is often 40 ⁇ m or more and 80 ⁇ m or less because of the controllability and apparatus dimensions.
- the nozzle By setting the distance c between the holes 15a to 0.3 m or less, the droplets sprayed from the two nozzle holes 15a can overlap each other.
- each spray nozzle 61 is provided with four nozzle holes 15a.
- the present invention is not limited to this, and 2, 3, or 5 is provided. Two or more may be provided.
- FIG. 9 is a view showing a cross section when the flue of the exhaust gas treatment apparatus according to Embodiment 4 of the present invention is viewed from the flow direction of the exhaust gas.
- symbol is attached
- the spray nozzles 15-1, 15-11 to 15-13, 15-23, and 15-24 provided on the short side of the flue 13.
- the amount is larger than the spray amount of spray nozzles 15-2 to 15-10 and 15-14 to 15-22 provided on the long side of the flue 13.
- the spray amount of the spray nozzles 15-2 to 15-10 and 15-14 to 15-22 is 1, the spray nozzles 15-1, 15-11 to 15-13, 15-23, and 15-24
- the spray amount is 1.5.
- 24 spray nozzles 15-11 to 15-24 are provided in the flue 13, but the present invention is not limited to this, and the flue 13 A plurality of spray nozzles may be provided according to the installation area.
- FIG. 10 is a conceptual diagram schematically showing the configuration of an exhaust gas treatment apparatus according to Embodiment 5 of the present invention.
- the exhaust gas treatment apparatus according to the present embodiment is the same as the configuration of the exhaust gas treatment apparatus 10 according to Embodiment 1 shown in FIG. .
- the exhaust gas treatment device 70 according to the present embodiment is on the downstream side of the region where NH 4 Cl in the flue 13 of the exhaust gas treatment device 10 according to the first embodiment shown in FIG.
- a mixer (mixing) that promotes mixing hydrogen chloride (HCl) gas as an oxidizing gas and ammonia (NH 3 ) gas as a reducing gas with the exhaust gas 12 when NH 4 Cl is vaporized.
- Means 71.
- the mixer 71 of the present embodiment is provided on the downstream side of the region where the NH 4 Cl solution 14 sprayed from the spray nozzle 15 is vaporized.
- the mixer 71 is preferably provided on the downstream side by 1 m or more from the supply position for supplying the NH 4 Cl solution 14. This is because in the practical plant operating conditions, mixer 71 is in contact with 1m smaller than the supply position of solution of NH 4 Cl 14, a mixer 71 before the droplets of the solution of NH 4 Cl 14 vaporizes This is because there are many cases. Therefore, by providing the mixer 71 on the downstream side of 1 m or more from the supply position for supplying the NH 4 Cl solution 14, mixing of HCl gas and NH 3 gas into the exhaust gas 12 can be further promoted. Further, the mixer 17 is set to about 10 m from the supply position of the NH 4 Cl solution 14 from the viewpoint of practical equipment arrangement.
- the first swirl flow inducing plate 73 and the second swirl flow inducing plate 74 are each formed in a substantially triangular shape.
- the swirl flow induction member 72 is viewed from the front.
- the first swirl flow induction plate 73 is positioned below the second swirl flow induction plate 74.
- the intermediate member 75 is a flat plate, and functions as a key for connecting the first swirl flow induction plate 73 and the second swirl flow induction plate 74.
- the mixer 71 is a unit in which six swirl flow inducing members 72 are arranged so as to be orthogonal to the flow direction of the exhaust gas 12, as shown in FIG.
- the number of the swirl flow inducing members 72 to be installed is appropriately changed according to the area of the flue 13 or the like.
- the mixer 71 is configured as a single unit in which six swirl flow inducing members 72 are arranged in the flow direction of the exhaust gas 12, but the present invention is not limited to this. Instead, a plurality of units in which a plurality of swirl flow inducing members 72 are arranged in the flow direction of the exhaust gas 12 may be installed. Further, the mixer 71 of this embodiment is provided with a unit in which a plurality of swirl flow inducing members 72 are arranged in a direction orthogonal to the flow direction of the exhaust gas 12, and a plurality of swirl flow inducing members 72 are arranged in the flow direction of the exhaust gas 12. A plurality of such units may be provided.
- FIG. 15 is a diagram schematically showing the gas flow of the exhaust gas when the mixer is installed in the flue
- FIG. 16 is a partially enlarged view of FIG. 15 and 16
- six swirl flow inducing members 72 are provided in the width direction of the flue 13 as in FIG.
- the exhaust gas 12 passes through the swirl flow induction member 72
- the exhaust gas 12 collides with the first swirl flow induction plate 73 and the second swirl flow induction plate 74 and the gas flow changes, Since it flows from the lower side to the upper side of the flue 13 while turning, the exhaust gas 12 is swirled by flowing so as to bypass the first swirl flow induction plate 73 and the second swirl flow induction plate 74. Since the flue 13 can flow from the lower side toward the upper side, the mixing of the exhaust gas 12 with the HCl gas and NH 3 gas can be promoted.
- the mixer 71 is provided on the downstream side of the region where the NH 4 Cl solution 14 sprayed from the spray nozzle 15 is vaporized, the mixer 71 is used before the droplets of the NH 4 Cl solution 14 are vaporized. Since contact with 71 can be prevented, damage to the flue 13 due to heat shock, corrosion of the flue 13, accumulation of ash in the exhaust gas 12, and the like can be prevented.
- the mixer 71 on the downstream side of the region where the NH 4 Cl solution 14 sprayed from the spray nozzle 15 vaporizes, the mixing of the NH 3 gas in the exhaust gas 12 in the flue 13 can be promoted. Therefore, the variation in the concentration distribution of the NH 3 gas in the exhaust gas 12 can be suppressed, and the variation in the concentration distribution of the NH 3 gas can be within a range of about 5%, for example, and can be made substantially uniform. For this reason, the reduction efficiency of NOx by the denitration catalyst in the reduction denitration apparatus 18 can be improved.
- the exhaust gas 12 in the flue 13 is mixed with HCl gas in addition to NH 3 gas. Can also promote. For this reason, the variation in the concentration distribution of the HCl gas in the exhaust gas 12 can be suppressed, and the variation in the concentration distribution of the HCl gas can be made substantially uniform, for example, within a range of about 5%. For this reason, in the reduction denitration apparatus 18, the oxidation performance of Hg in the denitration catalyst can be improved.
- FIG. 19 is a diagram illustrating the relationship between the pressure loss of the mixer and the dimensions of the mixer. As shown in FIG. 19, in order for the pressure loss of the mixer to be 25 mmAq or less, it is necessary to satisfy the following formula (11).
- the above formula (11) needs to be satisfied. Further, as an effect of the mixer 71, in order to make the concentration variation of the concentration of NH 3 in the exhaust gas 12 5% or less, the above formula (12) needs to be satisfied.
- the mixer 71 needs to satisfy
- D can be expressed as the following formula (14). 2L 2 / MIN (B, H) ⁇ D ⁇ 5 L 2 / MIN (B, H) (14)
- D can be expressed as the following equation (15). MIN (B, H) / 50 ⁇ D ⁇ 5 ⁇ MIN (B, H) (15)
- D is expressed as the above equation (10).
- the swirl flow inducing member 72 is installed in the flue 13 by having the width L and height D of the swirl flow inducing member 72 within the ranges of the above formulas (9) and (10). Therefore, it is possible to promote the mixing of HCl and NH 3 in the exhaust gas 12.
- the shapes of the first swirl flow inducing plate 73 and the second swirl flow inducing plate 74 are not limited to the triangular shape formed from the upper support plate 77 and the lower support plate 76 to the intermediate member 75, Any shape that can generate a swirling flow in the exhaust gas 12 and promote mixing of the exhaust gas 12 with HCl and NH 3 may be used.
- the shapes of the first swirl flow induction plate 73 and the second swirl flow induction plate 74 are curved, wave-shaped, etc. from one end side to the other end side of the second swirl flow induction plate 74 and the first swirl flow induction plate 73. Also good.
- the mixing of HCl and NH 3 in the exhaust gas 12 is promoted by providing a plurality of swirl flow inducing members 72 in the cross-sectional direction of the flue 13 as the mixer 71. Therefore, it is possible to make uniform the distribution of the concentration of NH 3 and HCl generated by the vaporization of the NH 4 Cl solution 14 sprayed from the spray nozzle 15. As a result, the reduction performance of Hg and the reduction performance of NOx can be improved by the denitration catalyst in the reductive denitration apparatus 18, the flue 13 is damaged by the heat shock, the flue 13 is corroded, and the ash is deposited in the exhaust gas 12. Etc. can be prevented.
- FIG. 20 is a diagram when viewed from the short side direction of the flue of the exhaust gas treatment apparatus according to Example 6 of the present invention
- FIG. 21 is a diagram when viewed from the long side direction of the flue.
- symbol is attached
- the flue 13 is on the downstream side of the supply position where the NH 4 Cl solution 14 is supplied into the flue 13, and the NH 4 Cl solution.
- a projecting member 81 is provided on the inner wall 13a of the flue 13 in the area where 14 droplets are vaporized.
- the shape of the protruding member 81 is a plate shape, but the present invention is not limited to this, and may be another shape such as a box shape or a triangular shape. .
- FIG. 7 is a diagram when viewed from the short side direction of the flue of the exhaust gas treatment apparatus according to Example 7 of the present invention
- FIG. 23 is a diagram when viewed from the long side direction of the flue.
- symbol is attached
- the exhaust gas treatment apparatus narrows the passage in the flue 13 downstream from the supply position for supplying the NH 4 Cl solution 14 into the flue 13.
- a portion 82 is provided.
- a vortex due to the gas flow of the exhaust gas 12 can be generated in the vicinity of the wall surface of the flue 13.
- Mixing of HCl gas and NH 3 gas in the exhaust gas 12 flowing in the vicinity can be promoted. For this reason, the concentration unevenness of HCl gas and NH 3 gas in the exhaust gas 12 can be suppressed, and the Hg oxidation performance and the NOx reduction performance can be improved in the reductive denitration device 18.
- the narrow passage 82 is formed by narrowing the passage of the flue 13, but the present invention is not limited to this.
- a constricted member 83 having the same shape as the constricted portion 82 may be provided on the wall surface of the flue 13.
- FIG. 8 is a view showing a part of the exhaust gas treatment apparatus according to Embodiment 8 of the present invention
- FIG. 27 is a partially enlarged perspective view showing a reference sign Z in FIG.
- symbol is attached
- the exhaust gas treatment apparatus is mixed with the guide vane 84 provided on the upstream side of the reduction denitration apparatus 18 to promote the mixing of HCl gas and NH 3 gas into the exhaust gas 12.
- a promotion auxiliary member 85 is provided.
- the mixing promotion auxiliary member 85 is a plurality of plate-like members extending in a direction orthogonal to the ribs 86 that connect the plurality of guide vanes 84 to each other.
- the mixing of HCl gas and NH 3 gas in the exhaust gas 12 can be promoted upstream of the reductive denitration device 18. For this reason, the concentration unevenness of HCl gas and NH 3 gas in the exhaust gas 12 can be suppressed, and the Hg oxidation performance and the NOx reduction performance can be improved in the reductive denitration device 18.
- FIG. 28 is a diagram simply showing the configuration of an exhaust gas treatment apparatus according to Embodiment 9 of the present invention.
- the exhaust gas treatment apparatus according to the present embodiment is the same as the configuration of the exhaust gas treatment apparatus according to Embodiments 1 to 8, the same members are denoted by the same reference numerals, and redundant description is omitted.
- the exhaust gas treatment apparatus 90 is provided between the NH 4 Cl solution supply means 16 and the reductive denitration apparatus 18, and ammonia (NH 3 ) as a reducing agent in the flue 13.
- An ammonia (NH 3 ) gas injection means 92 for supplying the gas 91 is provided.
- the nozzle 13 is configured to inject NH 3 gas 91 into the road 13. Further, the injection amount of the NH 3 gas 91 injected from the injection nozzle 95 is adjusted by the valve V4.
- the position supplied into the flue 13 from the injection nozzle 95 is 1 m or more downstream from the spray position of the NH 4 Cl solution 14. This is to prevent the droplet of the NH 4 Cl solution 14 from colliding with the injection nozzle 95.
- the exhaust gas treatment apparatus 90 after the NH 4 Cl solution 14 is sprayed into the flue 13, the NH 3 gas 91 is injected into the flue 13 from the NH 3 gas injection means 92.
- the NH 3 concentration in the low concentration region near the wall of the flue 13 can be increased, it is possible to cope with the concentration unevenness of the HCl gas and the NH 3 gas in the exhaust gas 12, while oxidizing the Hg in the reductive denitration device 18. While maintaining performance, the reduction performance of NOx can be improved.
- the balance between the NOx concentration and the Hg concentration in the exhaust gas 12 discharged from the combustion equipment such as the boiler 11 is different from the usual, and the NOx concentration is high, and it is necessary only by spraying the NH 4 Cl solution 14 into the flue 13.
- the NH 3 gas 91 is injected from the injection nozzle 95 into the flue 13, whereby the HCl gas supplied into the exhaust gas 12 in the flue 13, NH 3
- the amount of NH 3 gas necessary to reduce NOx can be supplied to the exhaust gas 12 while reducing the variation in the gas concentration distribution. Therefore, it is possible to cope with uneven concentration of HCl gas and NH 3 in the exhaust gas 12 and to improve the Hg oxidation performance and the NOx reduction performance in the reductive denitration device 18.
- the supply amount of the NH 3 gas 91 supplied from the NH 3 gas supply unit 93 may be controlled using the value of the NOx concentration meter 53.
- the NH 3 gas supply section 93 may be provided both between the NH 3 gas supply section 93 the HCl gas supply unit. Based on the flow velocity of the exhaust gas 12 measured by the flow meter 51, the spray amount, spray angle, and initial velocity of the NH 3 gas 91 and HCl gas supplied from the NH 3 gas supply unit 93 and the HCl gas supply unit can be adjusted. it can. As a result, NH 3 gas and HCl gas are separately supplied to the exhaust gas 12, so that appropriate measures can be taken even when the concentration of NOx or Hg in the exhaust gas 12 varies.
- the oxidation aid used for the oxidizing gas is not limited to HCl, and hydrogen halides such as hydrogen bromide (HBr) and hydrogen iodide (HI) other than HCl may be used as the oxidizing gas. Good.
- the exhaust gas treatment apparatus supplies to not adhere the solution of NH 4 Cl was sprayed flue to the inner wall of the flue, HCl gas, NH 3 generated from the droplets of solution of NH 4 Cl Since the mixing of the gas and the exhaust gas can be promoted, it is suitable for use in an exhaust gas treatment apparatus that removes Hg and NOx in the exhaust gas.
Abstract
Description
1) 本発明の第1の発明は、ボイラからの排ガス中に含まれる窒素酸化物、水銀を除去する排ガス処理装置であって、前記ボイラの下流の煙道内に、気化した際に酸化性ガスと還元性ガスとを生成する還元酸化助剤を複数の噴霧ノズルにより液体状で噴霧する還元酸化助剤供給手段と、前記排ガス中の窒素酸化物を前記還元性ガスで還元すると共に、前記酸化性ガス共存下で水銀を酸化する脱硝触媒を有する還元脱硝手段と、該還元脱硝手段において酸化された水銀をアルカリ吸収液を用いて除去する湿式脱硫手段と、を有し、前記噴霧ノズルが、前記還元酸化助剤を前記煙道の内壁に付着しないように前記煙道内に供給することを特徴とする排ガス処理装置にある。
x>l×sinα・・・(1)
a≦b/5・・・(2)
但し、aは噴霧ノズルのノズル孔のノズル孔間距離であり、bは煙道の断面の長さのうちの長辺側の長さである。
x>l×sinα・・・(3)
a≦b/5・・・(4)
但し、aは噴霧ノズルのノズル孔のノズル孔間距離であり、bは煙道の断面の長さのうちの長辺側の長さである。
MIN(B、H)/10≦L≦MIN(B、H)・・・(5)
MIN(B、H)/10≦D≦5×MIN(B、H)・・・(6)
但し、Bは設置位置における煙道の断面の一方の辺の長さであり、Hは煙道の断面の他方の辺の長さであり、MIN(B、H)は煙道の断面の一方の辺の長さB、煙道の断面の他方の辺の長さHのうちの何れかの短辺側の長さの値である。
また、前記還元酸化助剤が気化する前に前記煙道の壁面に付着するのを防止することができるため、前記煙道の腐食等に起因して発生する前記煙道の破損を防止することができる。
図1は、本発明の実施例1に係る排ガス処理装置の構成を示す概略図である。
図1に示すように、本実施例に係る排ガス処理装置10は、ボイラ11からの排ガス12中に含まれる窒素酸化物(NOx)、水銀(Hg)を除去する排ガス処理装置であって、ボイラ11の下流の煙道13内に、還元酸化助剤として塩化アンモニウム(NH4Cl)を含む塩化アンモニウム(NH4Cl)溶液14を複数の噴霧ノズル15により液体状で噴霧する塩化アンモニウム(NH4Cl)溶液供給手段(還元酸化助剤供給手段)16と、排ガス12中のNOxを還元性ガスとしてアンモニア(NH3)ガスで還元すると共に、酸化性ガスとして塩化水素(HCl)ガス共存下でHgを酸化する脱硝触媒を有する還元脱硝装置(還元脱硝手段)18と、脱硝された排ガス12を熱交換する熱交換器(エアヒータ)19と、脱硝された排ガス12中の煤塵を除去する集塵器20と、還元脱硝装置18において酸化されたHgをアルカリ吸収液として石灰石膏スラリー21を用いて除去する湿式脱硫装置22と、を有するものである。
また、本発明においては、還元酸化助剤とは、酸化性ガス共存下で水銀(Hg)を酸化して塩素化するのに用いられる酸化助剤と、還元性ガスによりNOxを還元する還元剤として機能するものをいう。本実施例では、酸化性ガスとしてHClガスが用いられ、還元性ガスとしてNH3ガスが用いられている。
NH4Cl溶液14の液滴径と、液滴が噴霧から蒸発するまでの時間と、液滴が蒸発するまでの移動距離との関係の一例を表1に示す。表1中、tはNH4Cl溶液14の液滴が噴霧から蒸発するまでの時間を表し、lは液滴が蒸発するまでの移動距離を表す。
図2に示すように、噴霧ノズル15は、噴霧ノズル15のノズル孔15aから噴霧されるNH4Cl溶液14の液滴の煙道13の壁面に対する噴射角度αに応じて、下記式(1)を満たすように設置することで、噴霧ノズル15から噴霧される液滴が煙道13の壁面に衝突しないようにすることができる。
l×sinα<x・・・(1)
但し、lは、NH4Cl溶液の液滴が蒸発するまでの移動距離を表す。
NH4Cl→NH3+HCl・・・(2)
4NO+4NH3+O2→4N2+6H2O・・・(3)
Hg+1/2O2+2HCl→HgCl2+H2O・・・(4)
CaCO3+SO2+0.5H2O→CaSO3・0.5H2O+CO2・・・(5)
CaSO3・0.5H2O+0.5O2+1.5H2O→CaSO4・2H2O・・・(6)
噴霧ノズル15の上流側には、排ガス12の流量を計測する流量計51が設けられている。流量計51により排ガス12の流量が測定される。流量計51により測定された排ガス12の流量の値は制御装置52に送られ、排ガス12の流量の値に基づいて噴霧ノズル15から噴射するNH4Cl溶液14の流量、角度、初速度などを調整することができる。
a≦b/5・・・(7)
但し、aは噴霧ノズルのノズル孔のノズル孔間距離であり、bは煙道の断面の長さのうちの長辺側の長さである。
a≦b/10・・・(8)
図10に示すように、本実施例に係る排ガス処理装置70は、前記図1に示した実施例1に係る排ガス処理装置10の煙道13のNH4Clが気化する領域よりも後流側に設けられ、NH4Clが気化した際に生成される酸化性ガスとして塩化水素(HCl)ガス及び還元性ガスとしてアンモニア(NH3)ガスを排ガス12と混合させるのを促進する混合器(混合手段)71を有するものである。
図11に示すように、本実施例の混合器71は、排ガス12に旋回流を生じさせる旋回流誘起部材72を排ガス12の流れ方向と直交するように6個配置されたユニットで形成されるものである。図12~図14に示すように、旋回流誘起部材72は、排ガス12の入口側に対向面73aを有する一対の第1の旋回流誘起板73と、排ガス12の排出側に対向面74aを有する一対の第2の旋回流誘起板74と、を有し、第1の旋回流誘起板73と第2の旋回流誘起板74とを連結する連結部として平板状の中間部材75において第1の旋回流誘起板73の対向面73aと第2の旋回流誘起板74の対向面74aとが異なるように各々連結されている。本実施例においては、第1の旋回流誘起板73の対向面73aと第2の旋回流誘起板74の対向面74aとが約90°異なるようにして配置されている。
MIN(B、H)/10≦L≦MIN(B、H)・・・(9)
MIN(B、H)/10≦D≦5×MIN(B、H)・・・(10)
但し、Bは設置位置における煙道の断面の長辺であり、Hは煙道の断面の短辺であり、MIN(B、H)は煙道の断面の長辺B、煙道の断面の短辺Hのうちの何れか短い方の辺である。煙道の断面の長辺B、短辺Hが同じ長さである場合にはどちらでもよい。
図19は、混合器の圧損と混合器の寸法の関係を示す図である。図19に示すように、混合器の圧損が25mmAq以下であるためには、下記式(11)を満たす必要がある。また、排ガス12中のNH3の濃度の濃度バラツキを5%以下とするためには、下記式(12)を満たす必要がある。
MIN(B、H)×D/L2≧2・・・(11)
MIN(B、H)×D/L2≦5・・・(12)
MIN(B、H)/10≦L≦MIN(B、H)・・・(9)
MIN(B、H)/10≦D・・・(13)
2L2/MIN(B、H)≦D≦5L2/MIN(B、H)・・・(14)
MIN(B、H)/50≦D≦5×MIN(B、H)・・・(15)
MIN(B、H)/10≦D≦5×MIN(B、H)・・・(10)
噴霧ノズル15の上流側には、排ガス12の流量を計測する流量計51が設けられ、排ガス12の流量が測定される。流量計51により測定された排ガス12の流量の値に基づいて制御装置52は噴射ノズル95から噴射するNH3ガス91の流量、角度、初速度などを調整することができる。
11 ボイラ
12 排ガス
13 煙道
14 塩化アンモニウム(NH4Cl)溶液
15、61 噴霧ノズル
16 塩化アンモニウム(NH4Cl)溶液供給手段(還元酸化助剤供給手段)
18 還元脱硝装置(還元脱硝手段)
19 熱交換器(エアヒータ)
20 集塵器
21 石灰石膏スラリー
22 湿式脱硫装置
25 塩化アンモニウム(NH4Cl)溶液供給管
26、33、47 空気
27、34 空気供給管
28 塩化アンモニウム(NH4Cl)溶液タンク
31、36 空気供給部
32 吹込み管
35 噴射孔
37 隙間
38−1~38−3 脱硝触媒層
39 整流板
41 装置本体
42 吸収液送給ライン
43 ノズル
44 浄化ガス
45 煙突
46 水
48 脱水器
49 石膏
51 流量計
52 制御装置
53 NOx濃度計
54−1、54−2 水銀(Hg)濃度計
55 塔底部
56 酸化還元電位測定制御装置(ORPコントローラ)
71 混合器(混合手段)
72 旋回流誘起部材
73 第1の旋回流誘起板
74 第2の旋回流誘起板
75 中間部材(連結部)
76 下部支持板
77 上部支持板
81 突状部材
82 くびれ部
83 くびれ部材
84 ガイドベーン
85 混合促進補助部材
86 リブ
91 アンモニア(NH3)ガス
92 アンモニア(NH3)ガス噴射手段
93 NH3ガス供給部
94 アンモニア(NH3)ガス送給通路
95 噴射ノズル
V1~V4 バルブ
Claims (17)
- ボイラからの排ガス中に含まれる窒素酸化物、水銀を除去する排ガス処理装置であって、
前記ボイラの下流の煙道内に、気化した際に酸化性ガスと還元性ガスとを生成する還元酸化助剤を複数の噴霧ノズルにより液体状で噴霧する還元酸化助剤供給手段と、
前記排ガス中の窒素酸化物を前記還元性ガスで還元すると共に、前記酸化性ガス共存下で水銀を酸化する脱硝触媒を有する還元脱硝手段と、
該還元脱硝手段において酸化された水銀をアルカリ吸収液を用いて除去する湿式脱硫手段と、を有し、
前記噴霧ノズルが、前記還元酸化助剤を前記煙道の内壁に付着しないように前記煙道内に供給することを特徴とする排ガス処理装置。 - 請求項1において、
少なくともガス流速、液滴初速、液滴径、排ガス温度、液滴温度から求められる液滴気化に要する距離lと、噴射角度αに基づいて、前記噴霧ノズルのノズル孔と前記煙道の内壁との最短距離xが、下記式を満たすように前記噴霧ノズルが配置されていることを特徴とする排ガス処理装置。
x>l×sinα・・・(1) - 請求項1又は2において、
前記還元酸化助剤が、塩化アンモニウムであることを特徴とする排ガス処理装置。 - 請求項1乃至3の何れか一つにおいて、
前記噴霧ノズルのノズル孔が、前記煙道の壁面から0.5m以上離した位置に設けられることを特徴とする排ガス処理装置。 - 請求項1乃至4の何れか一つにおいて、
複数の噴霧ノズルのノズル孔が、下記式を満たすように配置することを特徴とする排ガス処理装置。
a≦b/5・・・(2)
但し、aは噴霧ノズルのノズル間距離であり、bは煙道の断面の長さのうちの長辺側の長さである。 - 請求項1乃至5の何れか一つにおいて、
前記噴霧ノズルが、前記還元酸化助剤を噴霧するノズル孔を複数有することを特徴とする排ガス処理装置。 - 請求項6において、
前記ノズル孔同士の間隔が、0.3m以下であることを特徴とする排ガス処理装置。 - 請求項1乃至7の何れか一つにおいて、
各々の前記噴霧ノズルからの噴霧量が変更可能であることを特徴とする排ガス処理装置。 - 請求項1乃至8の何れか一つにおいて、
前記還元酸化助剤供給手段と前記還元脱硝手段との間に設けられ、前記煙道中にアンモニアガスを供給するアンモニアガス供給部、前記煙道内に塩化水素ガスを供給する塩化水素ガス供給部の何れか一方又は両方を有することを特徴とする排ガス処理装置。 - ボイラからの排ガス中に含まれる窒素酸化物、水銀を除去する排ガスの水銀除去方法であって、
前記ボイラの煙道内に気化した際に酸化性ガスと還元性ガスとを生成する還元酸化助剤を複数の噴霧ノズルにより液体状で噴霧する還元酸化助剤供給工程と、
脱硝触媒で前記排ガス中の窒素酸化物を前記還元性ガスで還元すると共に、前記酸化性ガス共存下で水銀を酸化する還元脱硝処理工程と、
該還元脱硝処理工程において酸化された水銀をアルカリ吸収液を用いて除去する湿式脱硫工程と、を有し、
前記噴霧ノズルが、前記還元酸化助剤を前記煙道の内壁に付着しないように前記煙道内に供給することを特徴とする排ガスの水銀除去方法。 - 請求項10において、
少なくともガス流速、液滴初速、液滴径、排ガス温度、液滴温度から求められる液滴気化に要する距離lと、噴射角度αに基づいて、前記噴霧ノズルのノズル孔と前記煙道の内壁との最短距離xが、下記式を満たすように前記噴霧ノズルのノズル孔が配置されていることを特徴とする排ガスの水銀除去方法。
x>l×sinα・・・(3) - 請求項10又は11において、
前記還元酸化助剤が、塩化アンモニウムであることを特徴とする排ガスの水銀除去方法。 - 請求項10乃至12の何れか一つにおいて、
前記噴霧ノズルのノズル孔を前記煙道の壁面から0.5m以上離した位置に設けることを特徴とする排ガスの水銀除去方法。 - 請求項10乃至13の何れか一つにおいて、
複数の噴霧ノズルのノズル孔を下記式を満たすように配置することを特徴とする排ガスの水銀除去方法。
a≦b/5・・・(4)
但し、aは噴霧ノズルのノズル間距離であり、bは煙道の断面の長さのうちの長辺側の長さである。 - 請求項10乃至14の何れか一つにおいて、
前記還元酸化助剤を供給する供給位置よりも上流側に、前記排ガスの流速を測定する流量測定工程を有し、
測定された前記排ガスの流速に基づいて前記還元酸化助剤の噴霧量、噴霧角度、初速度を調整することを特徴とする排ガスの水銀除去方法。 - 請求項10乃至15の何れか一つにおいて、
前記還元脱硝処理工程の前工程側に、前記排ガス中の窒素酸化物の濃度を測定する窒素酸化物濃度測定工程と、
前記還元脱硝処理工程の後工程側に、前記排ガス中の水銀の濃度を測定する水銀濃度測定工程とを含み、
前記窒素酸化物濃度測定工程により得られた前記排ガス中の窒素酸化物の濃度と、前記水銀濃度測定工程により得られた前記排ガス中の水銀の濃度との何れか一方又は両方に基づいて、前記還元酸化助剤供給工程において供給する前記還元酸化助剤の供給量を調整することを特徴とする排ガスの水銀除去方法。 - 請求項15又は16において、
前記還元酸化助剤供給工程と前記還元脱硝処理工程との間に、前記煙道中にアンモニアガスを供給するアンモニアガス供給工程、前記煙道中に塩化水素ガスを供給する塩化水素ガス供給工程の何れか一方又は両方を含み、
前記流量測定工程により測定された前記排ガスの流速に基づいて前記アンモニアガス供給工程より供給する前記アンモニアガス、前記塩化水素ガス供給工程より供給する前記塩化水素ガスの何れか一方又は両方の噴霧量、噴霧角度、初速度を調整することを特徴とする排ガスの水銀除去方法。
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CA2769861C (en) | 2014-06-03 |
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