WO2018124289A1

WO2018124289A1 - Exhaust gas treatment apparatus and exhaust gas treatment method

Info

Publication number: WO2018124289A1
Application number: PCT/JP2017/047299
Authority: WO
Inventors: 鵜飼　展行; 英夫鈴木; 茂吉岡; 櫻井　秀明; 龍上戸; 竹内　和久; 嘉晃伊藤; 裕中小路; 加藤　玲朋
Original assignee: 三菱重工業株式会社
Priority date: 2016-12-28
Filing date: 2017-12-28
Publication date: 2018-07-05
Also published as: JP2018108549A

Abstract

Provided are an exhaust gas treatment apparatus and an exhaust gas treatment method with which it is possible to recover sulfur contained in a desulfurization waste liquid and to reduce the released amount of the desulfurization waste liquid. An exhaust gas treatment apparatus 1 is provided with: an exhaust desulfurization section 11 that cleans combustion exhaust gas and discharges a desulfurization waste liquid W₁₁ that contains sulfate ions; and a membrane treatment section 12 that includes a separation membrane, which separates the desulfurization waste liquid W₁₁ into a first concentrated liquid W₂₁ in which the sulfate ions are concentrated and a first permeate W₂₂ in which the amount of the sulfate ions has been reduced by means of membrane separation, and that supplies the first concentrated liquid W₂₁ to the exhaust desulfurization section 11 while discharging the permeate W₂₂.

Description

Exhaust gas processing apparatus and exhaust gas processing method

The present invention relates to an exhaust gas treatment apparatus and an exhaust gas treatment method, and more particularly to an exhaust gas treatment apparatus and an exhaust gas treatment method for desulfurizing a combustion exhaust gas.

In the past, there has been proposed a demineralization apparatus for obtaining permeated water and concentrated water by performing membrane separation of treated water with a nano separation membrane and a reverse osmosis membrane (for example, see Patent Document 1). In the desalting apparatus described in Patent Document 1, permeated water containing chloride ions separated by the nano separation membrane is made to flow down to the reverse osmosis membrane to further separate the membrane and the concentrated water separated by the nano separation membrane. Discharge to the outside of the demineralizer. Thereby, the permeated water from which the salt content contained in to-be-processed water was removed, and the concentrated water by which salt content was concentrated are obtained.

US Patent Application Publication No. 2010/0163471

By the way, in a coal-fired power plant, desulfurization treatment in which the sulfur content in the combustion exhaust gas is absorbed is generated by the desulfurization treatment in which the sulfur content contained in the combustion exhaust gas of coal is washed and removed by the lime gypsum slurry. Desulfurization waste water is discharged after sulfur content such as sulfate ion is solidified and separated as gypsum. However, since sulfur content such as sulfate ion remains in the desulfurization waste water, an exhaust gas treatment apparatus capable of recovering the sulfur content in the desulfurization waste water and capable of reducing the discharge flow rate of the desulfurization waste water is desired.

An object of the present invention is to provide an exhaust gas treatment device and an exhaust gas treatment method capable of recovering sulfur content in desulfurization waste water and capable of reducing the discharge rate of the desulfurization waste water.

The exhaust gas treatment apparatus according to the present invention comprises a flue gas desulfurization unit that cleans the flue gas and discharges desulfurization waste water containing sulfate ions; and the desulfurization waste water is concentrated with the first permeated water and sulfate ions reduced in sulfate ions A first membrane processing unit having a first separation membrane that performs membrane separation with the first concentrated water, and supplying the first concentrated water to the exhaust gas desulfurization unit, and discharging the first permeated water; It is characterized by having.

According to this configuration, since the first concentrated water in which sulfate ions in the desulfurization waste water are concentrated is supplied to the exhaust gas desulfurization unit by the membrane separation by the first separation membrane, the amount of drainage discharged from the first membrane processing unit is reduced. As well as being able to reduce sulfate ions in the first permeated water, it is possible to recover sulfate ions. Therefore, the sulfur content in the desulfurization waste water can be recovered, and an exhaust gas treatment apparatus capable of reducing the discharge flow rate of the desulfurization waste water can be realized. Moreover, since chloride ions in the desulfurization waste water are discharged to the outside of the exhaust gas treatment apparatus together with the first permeated water, the concentration of chloride ions returned to the flue gas desulfurization section of the first concentrated water is reduced to It can also prevent the decline. Furthermore, since the first concentrated water returned to the flue gas desulfurization unit can also be used as washing water for the combustion exhaust gas, it is also possible to reduce makeup water supplied from the outside to the flue gas desulfurization unit.

In the exhaust gas treatment apparatus of the present invention, it is preferable that the first separation membrane has a chloride ion transmission rate higher than that of the sulfate ion in the desulfurization waste water. With this configuration, it is possible to efficiently discharge the chloride ion which causes the deterioration of the desulfurization performance in the exhaust gas desulfurization section together with the first permeated water to the outside of the exhaust gas treatment apparatus. The amount of chloride ions can be reduced, and the deterioration of the desulfurization performance of the flue gas

In the exhaust gas treatment apparatus of the present invention, it is preferable to have a dilution water supply unit for supplying dilution water for diluting the desulfurization waste water. According to this configuration, since the desulfurization waste water is diluted with the dilution water, it is possible to reduce the concentration of the scale component in the desulfurization waste water supplied to the first membrane processing unit. Thereby, even when the concentration of the scale component in the desulfurization effluent is high, it is possible to prevent the deposition of the scale in the first separation membrane of the first membrane treatment unit.

In the exhaust gas treatment apparatus of the present invention, the dilution water supply unit is a makeup water supply unit that supplies makeup water to the flue gas desulfurization unit, and the makeup water supply unit is at least one of the makeup water as the dilution water. It is preferable to supply 1 part to the desulfurization waste water. According to this configuration, since the desulfurization waste water is diluted with the makeup water, the concentration of the scale component in the desulfurization waste water supplied to the first membrane processing unit can be reduced. Thereby, even when the concentration of the scale component in the desulfurization waste water is high, it is possible to prevent the deposition of the scale in the first separation membrane of the first membrane treatment unit. Moreover, since desulfurization wastewater is diluted using at least a part of the makeup water supplied to the flue gas desulfurization section, it is possible to prevent the deposition of scale in the first separation membrane only by providing the makeup water branch line in the existing facility It becomes.

In the exhaust gas treatment apparatus of the present invention, it is preferable that a pretreatment unit is provided which performs pretreatment for removing scale components in the desulfurization wastewater and supplies the desulfurization wastewater subjected to the pretreatment to the first membrane processing unit. . With this configuration, the scale component contained in the desulfurization waste water discharged from the flue gas desulfurization unit is removed by the pretreatment unit at a stage preceding the first membrane treatment unit, so that the pretreatment water introduced into the first membrane treatment unit It is possible to significantly reduce the scale component of Thereby, even when the content of the scale component in the desulfurization waste water is high, it is possible to prevent the deposition of the scale in the first separation membrane of the first membrane processing unit.

In the exhaust gas processing device of the present invention, the first membrane processing unit can circulate at least one of the first permeated water and the first concentrated water to the desulfurization wastewater supplied to the first membrane processing unit. And controlling the flow rate of at least one of the first permeated water and the first concentrated water to be circulated to the desulfurization drainage when the chloride ion concentration of the first concentrated water exceeds a reference value. It is preferable that a flow control unit is provided to set the chloride ion concentration in the concentrated water below the reference value. With this configuration, the exhaust gas processing apparatus can control the chloride ion concentration in the first concentrated water supplied from the first membrane processing unit to the exhaust gas desulfurizing unit, so that the exhaust gas desulfurizing unit can be used together with the first concentrated water. The concentration of chloride ions supplied can be controlled below the reference value, and the deterioration of desulfurization performance can be prevented.

In the exhaust gas processing device of the present invention, the first membrane processing unit can circulate at least one of the first permeated water and the first concentrated water to the desulfurization wastewater supplied to the first membrane processing unit. And controlling a flow rate of at least one of the first permeated water and the first concentrated water to be circulated to the desulfurization drainage when the chloride ion concentration of the first permeated water is less than a reference value. It is preferable that a flow control unit is provided to set the chloride ion concentration in one permeate water to a reference value or more. With this configuration, the exhaust gas processing apparatus can control the chloride ion concentration in the first concentrated water supplied from the first membrane processing unit to the exhaust gas desulfurizing unit, so that the exhaust gas desulfurizing unit can be used together with the first concentrated water. The concentration of chloride ions supplied can be controlled below the reference value, and the deterioration of desulfurization performance can be prevented.

In the exhaust gas processing device of the present invention, the first membrane processing unit can circulate at least one of the first permeated water and the first concentrated water to the desulfurization wastewater supplied to the first membrane processing unit. And controlling the flow rate of at least one of the first permeated water and the first concentrated water circulating to the desulfurization waste water when the chloride ion concentration of the desulfurization waste water exceeds a reference value, thereby controlling the flow rate of the desulfurization waste water. It is preferable to have a flow rate control unit that sets the chloride ion concentration to a reference value or less. With this configuration, with this configuration, the exhaust gas processing apparatus can control the chloride ion concentration in the first concentrated water supplied from the first membrane processing unit to the exhaust gas desulfurizing unit, so the exhaust gas processing apparatus can discharge together with the first concentrated water. The chloride ion concentration supplied to the smoke desulfurization section can be controlled to a reference value or less, and the deterioration of desulfurization performance can be prevented.

In the exhaust gas treatment apparatus of the present invention, the first permeated water containing chloride ions is subjected to membrane separation into a second permeated water with reduced chloride ions and a second concentrated water with concentrated chloride ions. Preferably, a second membrane processing unit having a second separation membrane is provided. With this configuration, the second concentrated water from which chloride ions are concentrated and the second permeated water from which chloride ions are removed can be obtained by the membrane separation by the second separation membrane, so that the second permeation of high purity water is achieved. Water can be obtained, and the amount of water of the second concentrated water can be reduced with respect to the first permeated water supplied to the second membrane processing unit.

In the exhaust gas treatment apparatus of the present invention, preferably, the second membrane processing unit supplies the second permeated water as dilution water to the desulfurization wastewater. According to this configuration, since the desulfurization waste water is diluted with the second permeated water, it is possible to reduce the concentration of the scale component in the desulfurization waste water supplied to the first membrane processing unit. Thereby, even when the concentration of the scale component in the desulfurization effluent is high, it is possible to prevent the deposition of the scale in the first separation membrane of the first membrane treatment unit. In addition, since desulfurization wastewater is diluted using at least a part of the second permeated water discharged from the second membrane processing unit, the first separation is performed only by providing a permeated water supply line for supplying the second permeated water to the desulfurization wastewater. It becomes possible to prevent the deposition of scale in the film.

In the exhaust gas treatment apparatus of the present invention, it is preferable to include an evaporation processing unit that evaporates the second concentrated water to obtain evaporated water. With this configuration, it is possible to separate and recover the water of the second concentrated water as steam, so it is possible to significantly reduce the amount of drainage discharged from the exhaust gas processing device.

In the exhaust gas treatment apparatus of the present invention, it is preferable to have a post-treatment section for removing post-treatment water by removing impurities in the second concentrated water. According to this configuration, the impurities in the second concentrated water can be removed, so that the standard value of the discharge of the second concentrated water can be satisfied and discharged.

In the exhaust gas treatment apparatus of the present invention, it is preferable to include an evaporation processing unit that evaporates the first permeated water to obtain evaporated water. According to this configuration, the water content of the first permeate can be separated and recovered as steam, so that the amount of water discharged from the exhaust gas treatment device can be significantly reduced.

In the exhaust gas treatment apparatus of the present invention, it is preferable to include a post-treatment unit for removing post-treatment impurities by removing impurities in the first permeated water. With this configuration, impurities in the first permeated water can be removed, and therefore, it is possible to meet the standard value of the discharge of the second concentrated water and be discharged. Therefore, the amount of water discharged from the exhaust gas treatment device is significantly reduced. It becomes possible.

The exhaust gas treatment apparatus of the present invention preferably includes a solid-liquid separation unit for separating solid mercury and liquid mercury in the desulfurization waste water from the desulfurization waste water. According to this configuration, mercury attached to the first separation membrane of the first membrane processing unit can be reduced, and mercury in the first permeate can also be reduced to reduce the mercury concentration to the discharge reference value or less. , And the first permeated water can be discharged.

In the exhaust gas treatment apparatus of the present invention, it is preferable to have a mercury treatment unit for removing soluble mercury in the desulfurization waste water. According to this configuration, mercury attached to the first separation membrane of the first membrane processing unit can be reduced, and mercury in the first permeate can also be reduced to reduce the mercury concentration to the discharge reference value or less. , And the first permeated water can be discharged.

The exhaust gas treatment method of the present invention comprises a flue gas desulfurization step of washing combustion flue gas with a flue gas desulfurization section and discharging desulfurization waste water containing sulfate ions, and the first desulfurization waste water containing sulfate ions reduced. And the first concentrated water concentrated with sulfate ions by the first separation membrane, and supplying the first concentrated water to the flue gas desulfurization unit, and discharging the first permeated water, the first membrane treatment And a step of

According to this method, since the first concentrated water in which sulfate ions in the desulfurization waste water are concentrated is supplied to the exhaust gas desulfurization unit by the membrane separation by the first separation membrane, the amount of drainage discharged from the first membrane processing unit is reduced. As well as being able to reduce sulfate ions in the first permeated water, it is possible to recover sulfate ions. Therefore, the sulfur content in the desulfurization waste water can be recovered, and the exhaust gas treatment method capable of reducing the discharge flow rate of the desulfurization waste water can be realized. Moreover, since chloride ions in the desulfurization waste water are discharged to the outside together with the first permeated water, reduction in the amount of chloride ions returned to the flue gas desulfurization section of the first concentrated water prevents deterioration in the desulfurization performance. It can also be done. Furthermore, since the first concentrated water returned to the flue gas desulfurization unit can also be used as washing water for the combustion exhaust gas, it is also possible to reduce makeup water supplied from the outside to the flue gas desulfurization unit.

ADVANTAGE OF THE INVENTION According to this invention, the waste water containing a sulfur content can be reduced and the waste gas processing apparatus and waste gas processing method which can collect | recover sulfur content are realizable.

FIG. 1 is a schematic view showing an example of the exhaust gas processing system according to the first embodiment. FIG. 2A is an explanatory view of a case where the membrane processing unit according to the first embodiment includes a dialysis membrane by electrodialysis. FIG. 2B is an explanatory view of a case where the membrane processing unit according to the first embodiment includes a dialysis membrane by electrodialysis. FIG. 2C is an explanatory view of a case where the membrane processing unit according to the first embodiment includes a dialysis membrane by electrodialysis. FIG. 2D is an explanatory view of a case where the membrane processing unit according to the first embodiment includes a dialysis membrane by electrodialysis. FIG. 3 is a schematic view showing another example of the exhaust gas processing system according to the first embodiment. FIG. 4 is a view showing an example of an exhaust gas processing system according to the second embodiment. FIG. 5 is a view showing another example of the exhaust gas processing system according to the second embodiment. FIG. 6A is a diagram showing another example of the exhaust gas processing device according to the second embodiment. FIG. 6B is a diagram showing another example of the exhaust gas processing device according to the second embodiment. FIG. 7 is a schematic view showing an example of the exhaust gas processing system according to the third embodiment. FIG. 8 is a schematic view showing an example of the exhaust gas processing system according to the fourth embodiment. FIG. 9A is a schematic view showing an example of an exhaust gas processing system according to the fifth embodiment. FIG. 9B is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. FIG. 9C is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. FIG. 9D is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. FIG. 9E is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. FIG. 9F is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. FIG. 9G is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. FIG. 9H is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. FIG. 10 is a view showing an example of a film processing unit according to the fifth embodiment. FIG. 11A is a schematic view showing an example of an exhaust gas processing system according to a sixth embodiment. FIG. 11B is a schematic view showing another example of the exhaust gas processing system according to the sixth embodiment. FIG. 12A is a schematic view showing another example of the exhaust gas processing system according to the sixth embodiment. FIG. 12B is a schematic view showing another example of the exhaust gas processing system according to the sixth embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. In addition, this invention is not limited to each following embodiment, It can change suitably and can be implemented. Further, the following embodiments can be implemented in combination as appropriate.

First Embodiment
FIG. 1 is a schematic view showing an example of the exhaust gas processing system according to the first embodiment. As shown in FIG. 1, in the exhaust gas processing apparatus 1 according to the present embodiment, the desulfurization drainage W ₁₁ discharged from the exhaust gas desulfurization unit 11 is concentrated in sulfur content by the membrane processing unit (first film processing unit) 12. concentrated water W ₂₁ and sulfur content is membrane separated into permeate W ₂₂ removed, by supplying the concentrated water W ₂₁ to flue gas desulfurization unit 11, reducing the sulfur content in the permeate water W ₂₂ It is The sulfur content here is, for example, sulfur dioxide gas (SO ₂ ) in the combustion exhaust gas, various ions generated when the combustion exhaust gas is cleaned by the exhaust gas desulfurization unit 11 (SO ₃ ²⁻ , HSO ₃ ⁻ ) , Gypsum (CaSO ₄ ), sulfur which is generated by reaction with Ca derived from sulfate ion (SO ₄ ^2- ) generated by oxidation of various ions and calcium carbonate CaCO 3 supplied from the outside in the flue gas desulfurization unit 11, sulfur General oxides, peroxides such as S ₂ O ₆ ²⁻ , S ₂ O ₈ ^{2− and the} like can be mentioned.

The exhaust gas processing apparatus 1 includes an exhaust gas desulfurization unit 11 that desulfurizes sulfur in the combustion exhaust gas, and a film processing unit 12 provided downstream of the exhaust gas desulfurization unit 11. The exhaust gas desulfurization unit 11 cleans the combustion exhaust gas containing sulfur emitted from a coal-fired power plant or the like with washing water such as seawater. Further, the exhaust gas desulfurization unit 11 discharges the desulfurization waste water W ₁₁ as an exhaust gas absorption waste water containing a sulfur component generated by absorbing the combustion exhaust gas into the washing water through the desulfurization waste water supply line L ₁ to perform a film The data is supplied to the processing unit 12. The desulfurization waste water W ₁₁ is derived from monovalent ion components such as sodium ion (Na ⁺ ) and chloride ion (Cl ⁻ ), calcium ion (Ca ²⁺ ), magnesium ion (Mg ²⁺ ) and sulfur in combustion exhaust gas. Containing divalent ion components such as sulfate ions. FGD unit 11, by adding a slurry containing calcium ions dispersed like by pulverizing in water limestone desulfurization effluent W _11, the sulfate ions in the desulfurization effluent W _11, the flue gas desulfurization unit 11 Solidify as gypsum (CaSO ₄ ) and recover. Incidentally, chloride ions and sulfate ions in the desulfurization effluent W ₁₁ are derived from the combustion exhaust gas and makeup water W _{5 (see} FIG. 5), calcium ions and magnesium ions, limestone (carbonate is added to desulfurization waste water W ₁₁ It is derived from calcium (CaCO ₃ ).

The membrane processing unit 12 separates the membrane of the desulfurization waste water W ₁₁ discharged from the flue gas desulfurization part 11 into concentrated water W ₂₁ where sulfate ions are concentrated and permeate water W ₂₁ where sulfate ions are removed. Not shown: provided with a first separation membrane). Here, concentrated water W ₂₁ where sulfate ion is concentrated is the concentrated water where the ratio of sulfate ion to chloride ion ([SO ₄ ²⁻ ] / [Cl ⁻ ]) is larger than desulfurization waste water W ₁₁ (the following (It is also simply referred to as “concentrated water W ₂₁ ”), and the permeated water W ₂₂ from which sulfate ions have been removed is desulfurized by the ratio of sulfate ion to chloride ion ([SO ₄ ^2- ] / [Cl ⁻ ]) It is a permeated water (hereinafter, also simply referred to as “permeated water W ₂₂ ”) smaller than the drained water W ₁₁ . The membrane processing unit 12 supplies the concentrated water W ₂₁ in which the sulfate ion is concentrated to the exhaust gas desulfurization unit 11, and discharges the permeate water W ₂₂ in which the sulfate ion is removed as drainage. That is, in this embodiment, the sulfate ions as the scale components in the desulfurization effluent W _11, is recovered by solid as gypsum in flue gas desulfurization unit 11 and returned to the flue gas desulfurization unit 11 together with the concentrated water W _21. As a result, the exhaust gas processing apparatus 1 can reduce the amount of drainage containing sulfur that is discharged from the membrane processing unit 12 and can reduce the concentration of sulfate ions in the permeate water W _{22 that} causes scale components such as gypsum. , reduction in discharge amount of the desulfurization waste water from the exhaust gas treatment apparatus 1 with is possible, it is possible to suppress the scale deposition, such as gypsum in the permeate W ₂₂ in a later step.

The separation membrane, those permeability of chloride ion is preferably high relative to the transmittance of the sulfate ions in the desulfurization effluent W _11. Thus, since the chloride ions cause a reduction in desulfurization performance in the desulfurization unit 11 together with the permeate W ₂₂ can be efficiently discharged to the outside of the exhaust gas treatment apparatus 1, the flue gas desulfurization unit 11 together with the concentrated water W ₂₁ The amount of chloride ions supplied can be reduced, and the deterioration of the desulfurization performance of the exhaust gas desulfurization unit 11 can be prevented, and the amount of chloride ions in the exhaust gas desulfurization unit 11 is maintained below the reference value to reduce exhaust gas It also makes it possible to prevent corrosion of parts. According to the present embodiment, the transmittance is the ratio of various ions concentration permeate W in ₂₂ passing through the separation membrane for various ion concentration in the desulfurization effluent W _11.

The separation membrane, from the viewpoint of selectively membrane separating the chloride ions and sulfate ions, as the transmittance of the sulfate ion is less preferably a divalent ion component in the desulfurization effluent W _11. Moreover, as a separation membrane, from the viewpoint of preventing the deterioration of the desulfurization performance of the flue gas desulfurization section 11, one having a high permeability of chloride ions which are monovalent ion components is preferable. From the viewpoint of selectively separating the sulfate ion and the chloride ion as scale components in the permeate water W ₂₂ as the separation membrane, the permeability of the sulfate ion (hereinafter, also simply referred to as “sulfate ion permeability”) 50% or less is preferable, 20% or less is more preferable, and 10% or less is preferable. In addition, as the separation membrane, the chloride ion permeability (hereinafter referred to simply as “permeation of chloride ion”) from the viewpoint of reducing the chloride ion concentration in the concentrated water W ₂₁ returned to the flue gas desulfurization unit 11 to prevent the desulfurization performance. 10% or more is preferable, 20% or more is more preferable, and 50% or more is preferable. In view of the above, as the separation membrane, the transmittance of the sulfate ion is preferable that the following transmission of chloride ions in the desulfurization effluent W _11, chloride ion permeability sulfate ion permeability is not more than 50% Is more preferably 50% or more, the sulfate ion permeability is 20% or less and the chloride ion permeability is more preferably 80% or more, and the sulfate ion permeability is 10% or less and the chloride ion is It is even more preferable that the transmittance is 90% or more. Examples of separation membranes include nanofiltration (NF) membranes, reverse osmosis (RO) membranes, ion exchange membranes, dialysis membranes by electrodialysis and diffusion dialysis, and separation membranes by electrophoresis. The separation membrane, among these, the sulfate ions in the permeate W ₂₂ from the viewpoint of efficiently removing, preferably dialysis membrane by nanofiltration membrane and electrophoresis, nanofiltration membranes are more preferable. As the nanofiltration membrane, for example, trade name: NTR7250 (manufactured by Nitto Denko Corporation), NF40HF and NF50 (manufactured by Dow Chemical Co.) can be used.

When a dialysis membrane by electrodialysis is used as the separation membrane, for example, the following configuration can be employed. FIGS. 2A to 2D are explanatory views in the case where the membrane processing unit according to the present embodiment includes a dialysis membrane by electrodialysis. In the example shown in FIG. 2A, the membrane processing unit 12 includes a dialysis membrane 25A having a cation exchange membrane 23 and an anion exchange membrane 24 alternately arranged between the anode 21 and the cathode 22. The cation exchange membrane 23 is permeable to cations such as monovalent sodium ions, potassium ions (K ⁺ ) and divalent calcium ions, and is an anion such as monovalent chloride ions and divalent sulfate ions. I block movement. The anion exchange membrane 24 transmits anions such as monovalent chloride ions and divalent sulfate ions, and blocks migration of cations such as monovalent sodium ions, potassium ions and divalent calcium ions. Dialysis membrane 25A is membrane separation the desulfurization effluent _{W 11} supplied from the flue gas desulfurization unit 11 to the film processing section 12 to the concentrated water _{W 21} and permeate _{W 22.}

Desulfurization drainage W ₁₁ supplied from the exhaust gas desulfurization unit 11 to the membrane processing unit 12 is supplied to the dialysis membrane 25 A, and a direct current is caused to flow by the anode 21 and the cathode 22. Thus, cations such as monovalent sodium ions and divalent calcium ions in the desulfurization effluent W ₁₁ is thereby transmitted through the cation exchange membrane 23, moves blocked by the anion exchange membrane 24. Further, the monovalent chloride ion and the divalent sulfate ion in the desulfurization waste water _W11A permeate the anion exchange membrane 24 and move by being blocked by the cation exchange membrane 23. As a result, concentrated water from which sodium ions, calcium ions, chloride ions and sulfate ions have been removed between ion exchange membranes having the anion exchange membrane 24 on the anode 21 side and the cation exchange membrane 23 on the cathode 22 side. W ₂₁ is obtained. In addition, between ion exchange membranes having the cation exchange membrane 23 on the anode 21 side and the anion exchange membrane 24 on the cathode 22 side, permeated water W in which sodium ion, calcium ion, chloride ion and sulfate ion are concentrated ₂₂ are obtained. The concentrated water W ₂₁ is supplied to the flue gas desulfurization unit 11 via a concentrated water supply line L ₂₁ . Furthermore, permeate W ₂₂ via the permeate discharge line L ₂₂ while being discharged to the outside of the film processing section 12, the desulfurization waste water W as the circulating permeate W _22A through at least part of the permeate circulation line L _22A ₁₁ are circulated to the dialysis membrane 25A.

In the example shown in FIG. 2B, the membrane processing unit 12 includes a dialysis membrane 25B having a cation exchange membrane 23 and a monovalent selectively permeable anion exchange membrane 24A alternately disposed between the anode 21 and the cathode 22. . The cation exchange membrane 23 transmits cations such as monovalent sodium ions, potassium ions and divalent calcium ions, and blocks migration of anions such as monovalent chloride ions and divalent sulfate ions. The monovalent permselective anion exchange membrane 24A is permeable to monovalent anions such as monovalent chloride ions, and cations such as monovalent sodium ions, potassium ions and divalent calcium ions, and divalent ions. Block the movement of polyvalent anions such as sulfate ions. The dialysis membrane 25 B separates the desulfurization waste water W ₁₁ supplied from the flue gas desulfurization part 11 to the membrane processing part 12 into concentrated water W ₂₁ and permeate water W ₂₂ .

The desulfurized drainage W ₁₁ supplied from the exhaust gas desulfurization unit 11 to the membrane processing unit 12 is supplied to the dialysis membrane 25 B, and a direct current is caused to flow by the anode 21 and the cathode 22. As a result, cations such as monovalent sodium ion and divalent calcium ion in the desulfurization waste water W ₁₁ permeate through the cation exchange membrane 23 and are blocked by the monovalent permselective anion exchange membrane 24A ion exchange membrane. To move. In addition, monovalent chloride ions in the desulfurization waste water W ₁₁ permeate through the monovalent selective anion exchange membrane 24 and move by being blocked by the cation exchange membrane 23. Divalent sulfate ions in the desulfurization effluent W ₁₁ is moved blocked by the cation exchange membrane 23 and a monovalent permselective anion exchange membrane 24A. As a result, sodium ion, calcium ion and chloride ion are removed between the ion exchange membranes having the monovalent selectively permeable anion exchange membrane 24A on the anode 21 side and the cation exchange membrane 23 on the cathode 22 side. The concentrated water W ₂₁ in which the sulfate ion is concentrated is obtained. In addition, sodium ion, calcium ion and chloride ion are concentrated between the ion exchange membranes having the cation exchange membrane 23 on the anode 21 side and the monovalent permselective anion exchange membrane 24A on the cathode 22 side, and sulfuric acid A permeated water W ₂₂ from which ions have been removed is obtained. The concentrated water W ₂₁ is supplied to the flue gas desulfurization unit 11 via a concentrated water supply line L ₂₁ . Furthermore, permeate W ₂₂ via the permeate discharge line L ₂₂ while being discharged to the outside of the film processing section 12, the desulfurization waste water W as the circulating permeate W _22A through at least part of the permeate circulation line L _22A ₁₁ are circulated to the dialysis membrane 25B.

In the example shown in FIG. 2C, the membrane processing unit 12 includes a dialysis membrane 25C having monovalent permselective cation exchange membranes 23A and anion exchange membranes 24 alternately arranged between the anode 21 and the cathode 22. . The monovalent permselective cation exchange membrane 23A is permeable to monovalent cations such as monovalent sodium ions and potassium ions, and is a polyvalent cation such as divalent calcium ions, and monovalent chlorides. Block the migration of anions such as organic ions and divalent sulfate ions. The anion exchange membrane 24 is permeable to anions such as monovalent chloride ions and divalent sulfate ions, and has cations such as monovalent sodium ions, potassium ions (K ⁺ ) and divalent calcium ions. I block movement. The dialysis membrane 25 C separates the desulfurization waste water W ₁₁ supplied from the flue gas desulfurization part 11 to the membrane processing part 12 into concentrated water W ₂₁ and permeate water W ₂₂ .

Desulfurization drainage W ₁₁ supplied from the exhaust gas desulfurization unit 11 to the membrane processing unit 12 is supplied to the dialysis membrane 25 C, and a direct current is caused to flow by the anode 21 and the cathode 22. Thus, monovalent cations such as monovalent sodium ions in the desulfurization effluent W ₁₁ is thereby transmitted through the monovalent permselective cation exchange membranes 23A, moves blocked by the anion exchange membrane 24. Moreover, divalent calcium ions in the desulfurization effluent W _11A moves blocked by the monovalent permselective cation exchange membranes 23A and anion exchange membrane 24. The monovalent chloride ion and the divalent sulfate ion in the desulfurization waste water _W11A permeate through the anion exchange membrane 24 and move by being blocked by the monovalent selectively permeable cation exchange membrane 23A. As a result, sodium ion, chloride ion and sulfate ion are removed between ion exchange membranes having the anion exchange membrane 24 on the anode 21 side and the monovalent permselective cation exchange membrane 23A on the cathode 22 side. Concentrated water W ₂₁ in which calcium ions are concentrated is obtained. In addition, sodium ion, chloride ion and sulfate ion are concentrated between ion exchange membranes having the monovalent permselective cation exchange membrane 23A on the anode 21 side and the anion exchange membrane 24 on the cathode 22 side, and calcium A permeated water W ₂₂ from which ions have been removed is obtained. The concentrated water W ₂₁ is supplied to the flue gas desulfurization unit 11 via a concentrated water supply line L ₂₁ . Furthermore, permeate W ₂₂ via the permeate discharge line L ₂₂ while being discharged to the outside of the film processing section 12, the desulfurization waste water W as the circulating permeate W _22A through at least part of the permeate circulation line L _22A ₁₁ are circulated to the dialysis membrane 25C.

In the example shown in FIG. 2D, the membrane processing unit 12 has the monovalent permselective cation exchange membrane 23A and the monovalent permselective anion exchange membrane 24A alternately arranged between the anode 21 and the cathode 22. A dialysis membrane 25C is provided. The monovalent permselective cation exchange membrane 23A is permeable to monovalent cations such as monovalent sodium ions and potassium ions, and is a polyvalent cation such as divalent calcium ions, and monovalent chlorides. Block the migration of anions such as organic ions and divalent sulfate ions. The monovalent permselective anion exchange membrane 24A is permeable to monovalent chloride ions and is polyvalent such as cations such as monovalent sodium ions, potassium ions and divalent calcium ions, and divalent sulfate ions. Block the movement of anions. Dialysis membrane 25D, the membrane separating the desulfurization effluent _{W 11} supplied from the flue gas desulfurization unit 11 to the film processing section 12 to the concentrated water _{W 21} and permeate _{W 22.}

Desulfurization drainage W ₁₁ supplied from the exhaust gas desulfurization unit 11 to the membrane processing unit 12 is supplied to the dialysis membrane 25D. The desulfurization effluent _{W 11} supplied to the dialysis membrane 25D, the DC current flows through the anode 21 and cathode 22. Thus, the monovalent cations such as monovalent sodium ions in the desulfurization effluent W ₁₁ is transmitted through the monovalent permselective cation exchange membranes 23A, is blocked by the monovalent permselective anion exchange membrane 24A Move. The divalent calcium ion and divalent sulfate ions in the desulfurization effluent W ₁₁ is to be moved intercepted by the monovalent permselective cation exchange membranes 23A and monovalent permselective anion exchange membrane 24A. The monovalent chloride ion in the desulfurization effluent W ₁₁ is configured to transmit the monovalent permselective anion exchange membrane 24A, moves blocked by the monovalent permselective cation exchange membrane 23. As a result, sodium ion and chloride ion are removed between ion exchange membranes having the monovalent permselective anion exchange membrane 24A on the anode 21 side and the monovalent permselective cation exchange membrane 23A on the cathode 22 side. As a result, concentrated water W ₂₁ in which calcium ions and sulfate ions are concentrated is obtained. In addition, sodium ion and chloride ion are concentrated between ion exchange membranes having the monovalent permselective cation exchange membrane 23A on the anode 21 side and the monovalent permselective anion exchange membrane 24A on the cathode 22 side. Thus, the permeated water W _{22 from} which calcium ions and sulfate ions have been removed is obtained. The concentrated water W ₂₁ is supplied to the flue gas desulfurization unit 11 via a concentrated water supply line L ₂₁ . Furthermore, permeate W ₂₂ via the permeate discharge line L ₂₂ while being discharged to the outside of the film processing section 12, the desulfurization waste water W as the circulating permeate W _22A through at least part of the permeate circulation line L _22A ₁₁ are circulated to the dialysis membrane 25D.

In the membrane processing using a dialysis membrane by electrodialysis shown in FIGS. 2A to 2D, it is preferable to adjust the pH to be acidic (eg, pH 7 or less). This can prevent scale precipitation of calcium carbonate and magnesium hydroxide on various ion exchange membranes by reactions shown in the following reaction formulas (1) to (3) under basic conditions.
HCO ₃ ^- CO CO ₃ ^2- + H ⁺ (1)
CO ₃ ^2- + Ca ²⁺ CaCaCO ₃・・・ (2)
^{^{Mg 2+ + 2OH - ⇒Mg (OH}} ) 2 ↓ ··· (3)

The dialysis membrane 25A ~ 25D, from the viewpoint of discharging the chloride ions in the desulfurization effluent _{W 11} to efficiently permeate _{W 21,}

dialysis membrane

25A, 25B is preferred. As the dialysis membrane 25A ~ 25D, from the viewpoint of concentrated sulfuric acid ions in the desulfurization waste water _{W 11} to efficiently concentrate _{W 21,}

dialysis membrane

25B, 25D being preferred. As the dialysis membrane 25A ~ 25D, sodium ions contained in the desulfurization effluent W _11, chloride ions, membrane separation performance of the dialysis membrane to prevent the precipitation of gypsum scale the calcium ion and ion-exchange membranes based on sulfate ions The dialysis membranes 25B and 25C are preferable from the viewpoint of preventing the decrease in In view of the foregoing, the dialysis membrane 25A ~ 25D, the viewpoint of concentrated sulfuric acid ions in the desulfurization waste water _{W 11} efficiently concentrated water _{W 21,} the chloride ions in the desulfurization effluent _{W 11} to efficiently permeate _{W 22} viewpoint of discharge, sodium ions contained in the desulfurization effluent W _11, chloride ions, is possible to prevent deterioration of membrane separation performance of calcium ions and a dialysis membrane to prevent precipitation of gypsum scale to the ion-exchange membranes based on sulfate ions The dialysis membrane 25B is particularly preferable from the viewpoint of

Next, the entire operation of the exhaust gas processing device 1 will be described. Desulfurization effluent W ₁₁ containing sulfur discharged from flue gas desulfurization unit 11 is supplied to the film processing section 12 through the desulfurization effluent supply line L _1. Desulfurization effluent W ₁₁ supplied to the film processing section 12, sulfate ion and a sulfate ion and a concentrated water W ₂₁ enriched is membrane separated into permeate W ₂₂ removed by the separation membrane. The concentrated water W ₂₁ subjected to membrane separation in the membrane processing unit 12 is supplied to the flue gas desulfurization unit 11 via the concentrated water supply line L ₂₁ and after gypsum is removed in the flue gas desulfurization unit 11, the flue gas desulfurization is performed. It is discharged as desulfurization waste water _{W 11} from part 11. Further, the permeated water W ₂₂ subjected to membrane separation in the membrane processing unit 12 is discharged from the membrane processing unit 12 via the permeated water discharge line L ₂₂ .

As described above, according to the present embodiment, the concentrated water W _{21 in} which the sulfate ion in the desulfurization waste water W ₁₁ is concentrated is supplied to the exhaust gas desulfurization unit 11 by the membrane separation by the separation membrane. Since the amount of waste water discharged from 12 can be reduced and at the same time the sulfate ion of the permeate water W ₂₂ can be reduced, the sulfate ion can be recovered. Therefore, the sulfur content in the desulfurization waste water can be recovered, and the exhaust gas processing device 1 capable of reducing the discharge flow rate of the desulfurization waste water can be realized. Moreover, since the chloride ions in the desulfurization effluent W ₁₁ is discharged to the outside of the exhaust gas treatment apparatus 1 with the medium permeate W _22, desulfurization by chloride ions due to the return of the flue gas desulfurization unit 11 of the concentrated water W ₂₁ It is also possible to prevent performance degradation. Furthermore, since the concentrated water W ₂₁ returned to the exhaust gas desulfurization unit 11 can also be used as cleaning water for combustion exhaust gas, it is also possible to reduce makeup water supplied to the exhaust gas desulfurization unit 11 from the outside.

FIG. 3 is a schematic view showing another example of the exhaust gas processing system according to the first embodiment. As shown in FIG. 3, the exhaust gas processing apparatus 2 includes an exhaust gas desulfurization unit 11 that desulfurizes sulfur in the combustion exhaust gas, and a film processing unit 12 provided in a subsequent stage of the exhaust gas desulfurization unit 11. The film processing unit 12 includes a first film processing unit 121 provided downstream of the exhaust gas desulfurization unit 11 and a second film processing unit 122 provided downstream of the first film processing unit 121.

The first membrane processing unit 121 performs membrane separation of the desulfurized drainage W ₁₁ discharged from the flue gas desulfurization unit 11 into concentrated water W _{21 in} which sulfate ions are concentrated and permeate water W ₂₂ in which sulfate ions are removed. 1 A separation membrane (not shown) is provided. As the first separation membrane, the same one as the above-mentioned separation membrane can be used. The first membrane processing unit 121 supplies the concentrated water W ₂₁ in which the sulfate ion is concentrated to the exhaust gas desulfurization unit 11, and discharges the permeate water W ₂₂ in which the sulfate ion is removed. The first layer processing unit 121, i.e., in this embodiment, as gypsum in flue gas desulfurization unit 11 to return the sulfuric acid ions of scale components of the desulfurization waste water W ₁₁ to flue gas desulfurization unit 11 together with the concentrated water W ₂₁ Solidify and collect. As a result, the amount of drainage discharged from the membrane processing unit 12 can be reduced, and the concentration of sulfate ions in the permeate water W ₂₂ to be a scale component such as gypsum can be reduced, so that sulfate ions can be recovered.

The second membrane processing unit 122 is configured such that the first permeate water W ₂₂ containing chloride ions discharged from the first membrane processing unit 121 is separated from the second concentrated water W ₃₁ containing chloride ions and chloride ions. A second separation membrane (not shown) is membrane-separated into the reduced second permeate water W ₃₂ . The provision of the second film processing section 122, it is possible to obtain a second permeate W ₃₂ to monovalent ionic components such as sodium ions and chloride ions in the permeate W ₂₂ has been removed. The second separation membrane is not particularly limited as long as it can separate monovalent ion components from the first permeated water W _22. For example, a reverse osmosis membrane, a nanofiltration membrane, a dialysis membrane by electrodialysis, etc. are used . Among these, as the second separation membrane, in terms of salt rejection of the first permeate W _22, the reverse osmosis membrane is preferred.

Next, the entire operation of the exhaust gas processing device 2 will be described. The desulfurization waste water W ₁₁ containing the sulfur content discharged from the flue gas desulfurization part 11 is supplied to the first membrane processing part 121 of the membrane processing part 12 via the desulfurization waste water supply line L ₁ , and the sulfuric acid is removed by the first separation membrane. The membrane is separated into a first concentrated water W ₂₁ in which ions are concentrated and a first permeate water W ₂₂ in which sulfate ions are removed. Here, the first concentrated water W _{21 in} which the sulfate ion is concentrated is a concentrated water in which the ratio of the sulfate ion to the chloride ion ([SO ₄ ²⁻ ] / [Cl ⁻ ]) is larger than the desulfurization waste water W ₁₁ (Hereafter, it is also simply referred to as “first concentrated water W ₂₁ ”), and the ratio of sulfate ion to chloride ion ([SO ₄ ^2- ] / [is compared with the first permeated water W ₂₂ from which sulfate ion has been removed. Cl ⁻ ]) is permeated water (hereinafter, also simply referred to as “first permeated water W ₂₂ ”) smaller than the desulfurization waste water W ₁₁ . After the first concentrated water W ₂₁ subjected to membrane separation in the first membrane processing unit 121 is supplied to the exhaust gas desulfurization unit 11 via the concentrated water supply line L ₂₁ and gypsum is recovered in the exhaust gas desulfurization unit 11 It is discharged together with desulfurization waste water _{W 11} from flue gas desulfurization unit 11. The first permeate W ₂₂ which is membrane separation in the first layer processing section 121 is supplied to the second membrane unit 122 through permeate discharge line L _22, chloride ions concentrated by a second isolation layer The membrane is separated into the second concentrated water W ₃₁ and the second permeated water W ₃₂ from which chloride ions have been removed. The second concentrated water W ₃₁ separated by the second separation membrane is discharged from the second membrane processing unit 122 through the concentrated water discharge line L ₃₁ , and the second permeated water W ₃₂ is the permeated water discharge line L _32. Through the second membrane processing unit 122.

As described above, according to the present embodiment, since the first concentrated water W _{21 in} which the sulfate ion in the desulfurization waste water W ₁₁ is concentrated by the membrane separation by the first separation membrane is supplied to the exhaust gas desulfurization unit 11 The amount of drainage discharged from the first membrane processing unit 121 can be reduced, and the sulfate ion of the first permeate water W ₂₂ can be reduced. Therefore, the sulfur content in the desulfurization waste water can be recovered, and the exhaust gas processing device 2 capable of reducing the discharge rate of the desulfurization waste water can be realized. Moreover, in the desulfurization effluent W ₁₁ since chloride ions is discharged to the outside of the exhaust gas treatment apparatus 1 with the medium permeate W _22, the returned the chloride ion content of the flue gas desulfurization unit 11 of the concentrated water W ₂₁ The reduction can also prevent the desulfurization performance from deteriorating. Further, since the second concentrated water W _{31 in} which chloride ions are concentrated and the second permeate water W ₃₂ in which chloride ions are removed are obtained by the membrane separation using the second separation membrane, the second high-purity water is obtained. The permeate water W ₃₂ is obtained, and the second concentrated water W ₃₁ can be further concentrated to reduce the volume.

Second Embodiment
Next, a second embodiment will be described. In the following, the components common to the first embodiment described above are denoted by the same reference numerals. Further, differences from the above-described first embodiment will be mainly described, and redundant description will be avoided.

FIG. 4 is a view showing an example of an exhaust gas processing system according to the second embodiment. Figure 4 As shown in, the exhaust gas treatment apparatus 3 according to the present embodiment, in addition to the configuration of the exhaust gas treatment apparatus 1 shown in FIG. 1, diluting water supplying diluting water W ₄ to dilute the desulfurization effluent W ₁₁ The supply unit 13 is provided. By providing the dilution water supply unit 13 and diluting the desulfurization waste water W ₁₁ with the dilution water W ₄ , the concentration of divalent ion components such as sulfate ions as scale components in the desulfurization waste water W ₁₁ is reduced, It is possible to prevent the deposition of scale on the separation membrane of the membrane processing unit 12. The diluting water W _4, not particularly limited as long as it can reduce the concentration of the scale components in the desulfurization effluent W _11, for example, process water, or the like can be used river water and pond water. In the example shown in FIG. 4, the dilution water supply unit 13, there is shown an example for supplying diluting water W ₄ to the film processing section 12, dilution water supply unit 13, if diluted desulfurization effluent W ₁₁ dilution The water W ₄ may be supplied to other than the membrane processing unit 12. Dilution water supply unit 13, for example, may be supplied diluting water W ₄ in desulfurization waste water supply line L ₁ via the dilution water supply line L _41. In addition, the dilution water supply line L ₄₁ may be provided with a pretreatment unit that removes suspended solids in the dilution water W ₄ as necessary. The other configuration is the same as that of the exhaust gas processing device 1 shown in FIG.

Next, the entire operation of the exhaust gas processing device 3 will be described. Desulfurization effluent W ₁₁ containing sulfur discharged from flue gas desulfurization unit 11 is supplied to the film processing section 12 through the desulfurization effluent supply line L _1. After the desulfurization waste water W ₁₁ supplied to the membrane processing unit 12 is mixed with the dilution water W ₄ supplied from the dilution water supply unit 13 via the dilution water supply line L ₄₁ , the sulfate ion is concentrated by the separation membrane The membrane is separated into concentrated water W ₂₁ and permeated water W ₂₂ from which sulfate ion has been removed. Here, by the desulfurization effluent W ₁₁ is mixed with the diluting water W _4, the concentration of the scale components is reduced, it is possible to prevent the scale deposition in the separation membrane.

As described above, according to this embodiment, since diluting the desulfurization effluent W ₁₁ by diluting water W _4, reducing the concentration of the scale components in the desulfurization effluent W ₁₁ to be supplied to the film processing section 12 Is possible. Accordingly, even when a high concentration of the scale components in the desulfurization effluent W _11, it is possible to prevent the deposition of scale in the separation membrane of the film processing section 12.

FIG. 5 is a view showing another example of the exhaust gas processing system according to the second embodiment. As shown in FIG. 5, the exhaust gas treatment apparatus 4 supplies the makeup water W ₅ to the flue gas desulfurization unit 11 through the makeup water supply line L _5, via the makeup water branch line L ₄₂ film processor 12 at least a portion of the makeup water W ₅ comprises a makeup water supply 14 for supplying a diluting water to. That is, the exhaust gas processing device 4 shown in FIG. 5 also uses the makeup water supply unit 14 as the dilution water supply unit 13 shown in FIG. 4. In the example shown in FIG. 5, the makeup water supply 14, although an example is shown to be supplied to the film processing section 12 as a diluting water W ₄ at least a portion of the makeup water W _5, the makeup water supply 14 , at least a portion of the makeup water W ₅ if dilute the desulfurization effluent W ₁₁ may be supplied to the non-film processing section 12. Makeup water supply unit 14, for example, the desulfurization effluent supply line L ₁ through the makeup water branch line L ₄₂ may supply diluting water W _4. Also, the makeup water branch line L _42, may be provided with a pre-processing unit for removing suspended solid makeup water W ₅ as needed. The other configuration is the same as that of the exhaust gas processing device 3 shown in FIG.

Next, the entire operation of the exhaust gas processing device 4 will be described. Desulfurization effluent W ₁₁ containing sulfur discharged from flue gas desulfurization unit 11 is supplied to the film processing section 12 through the desulfurization effluent supply line L _1. Desulfurization effluent W ₁₁ supplied to the film processing section 12, after being mixed with makeup water W ₅ supplied from replenishing water supply unit 14 through the makeup water branch line L _42, sulfate ions are concentrated by the separation membrane The membrane is separated into concentrated water W ₂₁ and permeated water W ₂₂ from which sulfate ion has been removed. Here, by the desulfurization effluent W ₁₁ is mixed with makeup water W _5, the concentration of the scale components is reduced, it is possible to prevent the scale deposition in the separation membrane.

As described above, according to this embodiment, since diluting the desulfurization effluent W ₁₁ by makeup water W _5, reducing the concentration of the scale components in the desulfurization effluent W ₁₁ to be supplied to the film processing section 12 Can. Accordingly, even when the concentration of the scale components in the desulfurization effluent W ₁₁ high, it is possible to prevent the deposition of scale in the separation membrane of the film processing section 12. Moreover, since the desulfurization drainage W ₁₁ is diluted using at least a part of the makeup water W ₅ to be supplied to the flue gas desulfurization unit 11, the scale deposition in the separation membrane can be achieved simply by providing the makeup water branch line L ₄₂ in the existing facility. Can be prevented.

FIG. 6A is a diagram showing another example of the exhaust gas processing device according to the second embodiment. As shown in FIG. 6A, the exhaust gas treatment apparatus 5A, in addition to the configuration of the air pollution control apparatus 2 shown in FIG. 3, the permeate that is provided between the permeate discharge line L ₃₂ and desulfurization effluent supply line L ₁ A supply line L ₄₃ is provided. The second membrane processing unit 122 discharges the second permeated water W ₃₂ through the permeated water discharge line L ₃₂ and recycles at least a portion of the second permeated water W ₃₂ through the permeated water supply line L _43. Supply to desulfurization drainage W ₁₁ as W ₃₃ . That is, the exhaust gas processing apparatus 5A shown in FIG. 6A uses the second membrane processing unit 122 also as the dilution water supply unit 13 shown in FIG.

Next, the entire operation of the exhaust gas processing device 5A will be described. The desulfurization waste water W ₁₁ containing the sulfur content discharged from the flue gas desulfurization part 11 is supplied to the first membrane processing part 121 via the desulfurization waste water supply line L ₁ . Desulfurization effluent W ₁₁ supplied to the first layer processing section 121, after being mixed with the second permeate W ₃₂ supplied from the second membrane unit 122 through permeate supply line L _43, the first isolation The membrane separates the first concentrated water W ₂₁ in which the sulfate ion is concentrated by the membrane and the first permeate water W ₂₂ in which the sulfate ion is removed. Here, by the desulfurization effluent W ₁₁ is mixed with the second permeate W _32, since the concentration of the scale components is reduced, it is possible to prevent the scale deposition in the first separation membrane. The first permeated water W ₂₂ subjected to membrane separation in the first membrane processing unit 121 is supplied to the second membrane processing unit 122, and the second concentrated water W ₃₁ and chloride in which chloride ions are concentrated by the second separation membrane The membrane is separated into the second permeated water W ₃₂ from which the ions have been removed. At least a part of the second permeated water W ₃₂ membrane-separated by the second separation membrane is supplied to the desulfurization drainage W ₁₁ as circulating water W ₃₃ through the permeated water circulation line L _{43 and} to the outside of the exhaust gas treatment device 5A. Exhausted.

FIG. 6B is a diagram showing another example of the exhaust gas processing device according to the second embodiment. Further, as shown in Figure 6B, the exhaust gas treatment apparatus 5B includes a permeate supply line L ₄₄ that is provided between the permeate discharge line L ₂₂ and desulfurization effluent supply line L _1. The first membrane processing unit 121 discharges the first permeated water W ₂₂ through the permeated water discharge line L ₂₂ , and circulates at least a portion of the second permeated water W ₂₂ through the permeated water circulation line L _44. Supply to desulfurization drainage W ₁₁ as ₂₃ . That is, the exhaust gas processing apparatus 5B shown in FIG. 6B uses the first membrane processing unit 121 also as the dilution water supply unit 13 shown in FIG. The other configuration is the same as that of the exhaust gas processing device 3 shown in FIG.

Next, the entire operation of the exhaust gas processing device 5B will be described. The desulfurization waste water W ₁₁ containing the sulfur content discharged from the flue gas desulfurization part 11 is supplied to the first membrane processing part 121 via the desulfurization waste water supply line L ₁ . Desulfurization effluent W ₁₁ supplied to the first layer processing section 121, after being mixed with the first permeate W ₂₂ supplied from the first layer processing section 121 through the permeate supply line L _44, the first isolation The membrane separates the first concentrated water W ₂₁ in which the sulfate ion is concentrated by the membrane and the first permeate water W ₂₂ in which the sulfate ion is removed. Here, by the desulfurization effluent W ₁₁ is mixed with the second permeate W _32, since the concentration of the scale components is reduced, it is possible to prevent the scale deposition in the first separation membrane. The first permeated water W ₂₂ subjected to membrane separation in the first membrane processing unit 121 is supplied to the second membrane processing unit 122 and at least a portion thereof is desulfurized drainage through the permeated water supply line L ₄₄ as circulating water W ₂₃ It is supplied to the W _11. The first permeate water W ₂₂ supplied to the second membrane processing unit 122 is a second concentrate water W _{31 in} which chloride ions are concentrated by the second separation membrane and a second permeate water W ₃₂ in which chloride ions are removed. The membrane is separated and discharged.

As described above, according to this embodiment, since the dilution by the first permeate _{W 22} or second permeate _{W 32} of the desulfurization effluent _{W 11} as the circulating water _{W 23} or circulation water _{W 33,} first it is possible to reduce the concentration of the scale components in the desulfurization effluent W ₁₁ supplied to the membrane unit 121. Accordingly, even when a high concentration of the scale components in the desulfurization effluent W _11, it is possible to prevent the scale deposition in the first separation film of the first layer processing section 121. Moreover, since diluting the desulfurization effluent _{W 11} using at least a portion of the second permeate _{W 32} discharged from the second layer processing unit 122, the first separation film only by providing a permeate circulation line _L _{43, L 44} It is possible to prevent the precipitation of scale in

Third Embodiment
Next, a third embodiment will be described. In the following, the components common to the first embodiment described above are denoted by the same reference numerals. Further, differences from the above-described first embodiment will be mainly described, and redundant description will be avoided.

FIG. 7 is a schematic view showing an example of the exhaust gas processing system according to the third embodiment. As shown in FIG. 7, the exhaust gas treatment apparatus 6 of the present embodiment is provided at the latter stage of the flue gas desulfurization unit 11, and a pre-processing unit 15 for removing the scale components in the desulfurization effluent W _11. Preprocessing unit 15 removes the scale components such as calcium ions and magnesium ions contained in the desulfurization effluent W _11. Further, the pretreatment unit 15 supplies the first membrane treatment unit 121 with the pretreatment water W _{14 from} which the scale component in the desulfurization drainage has been removed. Note that the previous stage of the pre-processing unit 15, gypsum (CaSO ₄₎ a solid-liquid separating section for separating and removing from the desulfurization effluent of the solid component, such as a (not shown) may be provided contained in the desulfurization waste water W _11. The solid-liquid separation unit, in particular limited as long as it can separate and remove solid components from the desulfurization effluent W ₁₁ is not, for example, a belt filter, a belt press, filter press, centrifuge, hydrocyclone and various like settling tank A solid-liquid separation device can be used.

In the present embodiment, the pre-processing unit 15 is provided in the subsequent stage of the coagulation sedimentation unit 151 to which the desulfurization drainage W ₁₁ is supplied, the sand filtration unit 152 provided in the latter stage of the coagulation sedimentation unit 151, and the sand filtration unit 152 And the membrane filtration unit 153. In the present embodiment, an example has been described in which the pretreatment unit 15 includes the aggregation and precipitation unit 151, the sand filtration unit 152, and the membrane filtration unit 153, but the present invention is not limited to this configuration. The pretreatment unit 15 may include at least one of the sand filtration unit 152 or the membrane filtration unit 153. For example, the pretreatment unit 15 may include the coagulation sedimentation unit 151 and the sand filtration unit 152. The coagulation sedimentation unit 151 and the membrane filtration The unit 153 may be provided.

Flocculation unit 151, and solidifying salt 151a as the scale components in the desulfurization effluent W ₁₁ due lime soda method for solid-liquid separation from the desulfurization effluent W _11. The flocculation settling unit 151 is, for example, calcium carbonate (CaCO ₃ ) by adding calcium hydroxide (Ca (OH) ₂ ) and sodium carbonate (Na ₂ CO ₃ ) to the desulfurization waste water W ₁₁ to add calcium ions and magnesium ions. And solidify as magnesium hydroxide (Mg (OH) ₂ ) and separate from the desulfurization waste water W ₁₁ as sludge 151 a. For example, a settling tank such as a clarifier is used as the aggregation settling unit 151. The flocculation settling unit 151 supplies the sand filtration unit 152 with the desulfurization drainage W ₁₂ obtained by removing the sludge 151 a from the desulfurization drainage W ₁₁ .

Sand filtration unit 152 is, for example, by passing the desulfurization effluent W ₁₂ to a plurality of filter layers, the solid in the desulfurization effluent W ₁₂ min, specifically solids generated by the coagulation-sedimentation unit 151 (calcium carbonate (CaCO ₃₎ and magnesium hydroxide (Mg _(OH) 2)) and removing the particulate silicon dioxide (SiO ₂₎ a solid, such as content (suspended matter). Here, the sand filtration unit 152 may allow the sand filtration layer to permeate the desulfurization drainage W ₁₂ to remove the solid content. In addition, the sand filtration 152 supplies the membrane filtration 153 with the desulfurization waste water W _{13 from} which the solid content in the desulfurization waste water W ₁₂ has been removed.

The membrane filtration unit 153 is a solid substance (calcium carbonate (CaCO 2 (CaCO 2) remaining in the desulfurization drainage W ₁₃ by causing the desulfurization drainage W ₁₃ to permeate through the filtration membrane 153 a such as microfiltration and ultrafiltration membrane (UF: Ultra Filtration)). ₃ ) to obtain pretreated water W _{14 from} which solid content such as magnesium hydroxide (Mg (OH) ₂ )) and particulate silicon dioxide (SiO ₂ ) has been removed and to obtain washing waste W ₁₅ containing suspended components obtain. Further, the membrane filtration unit 153 supplies the pretreated water W ₁₄ to the membrane processing unit 12 and discharges the concentrated water W ₁₅ as drainage. The other configuration is the same as that of the exhaust gas processing device 1 shown in FIG.

Next, the entire operation of the exhaust gas processing device 6 will be described. The desulfurization waste water W ₁₁ containing the sulfur content discharged from the flue gas desulfurization part 11 is supplied to the coagulation sedimentation part 151 of the pretreatment part 15 via the desulfurization waste water supply line L ₁ . Slaked lime, sodium carbonate (Na ₂ CO ₃ ), etc. are added to the desulfurization waste water W ₁₁ supplied to the coagulating and settling part 151. Thereby, calcium ions and magnesium ions are solidified as calcium carbonate (CaCO ₃ ) and magnesium hydroxide (Mg (OH) ₂ ) and separated from the desulfurization drainage W ₁₁ as sludge 151 a. The desulfurization waste water W ₁₂ from which the sludge 151 a has been removed in the coagulation sedimentation part 151 is supplied to the sand filtration part 152 and permeates through the filter medium, whereby suspended substances in the desulfurization waste water W ₁₂ (carry ) Is removed. The desulfurization waste water W ₁₃ from which the suspended matter has been removed is supplied to the membrane filtration unit 153 and permeates through the filtration membrane 153 a, whereby suspended matter remaining in the desulfurization drainage W ₁₃ (carry over from the sand filtration ) is membrane separation in the pretreated water W ₁₄ and cleaning waste water W ₁₅ is removed. The membrane-separated pretreated water W ₁₄ is supplied to the membrane processing unit 12, and the cleaning drainage W ₁₅ is discharged out of the system. The other parts are the same as those of the exhaust gas processing device 1 shown in FIG.

As described above, according to the present embodiment, the scale component contained in the desulfurization waste water W ₁₁ discharged from the flue gas desulfurization part 11 is removed by the pre-treatment part 15 at the front stage of the membrane processing part 12 It is possible to significantly reduce the scale component in the pretreated water W ₁₄ introduced into the membrane processing unit 12. Accordingly, even when high content of scale components in the desulfurization effluent W _11, it is possible to prevent the deposition of scale in the separation membrane of the film processing section 12.

Fourth Embodiment
Next, a fourth embodiment will be described. In the following, the components common to the first embodiment described above are denoted by the same reference numerals. Further, differences from the above-described first embodiment will be mainly described, and redundant description will be avoided.

In the conventional exhaust gas treatment apparatus, when solid mercury and liquid mercury contained in the desulfurization waste water adhere to the surface of the separation membrane of the membrane treatment unit, the flow rate of the permeated water of the separation membrane may be reduced. Exhaust gas treatment apparatus according to the present embodiment, by removing the solid mercury and liquid mercury contained in the desulfurization effluent W _11, to prevent adhesion of the mercury to the surface of the separation membrane in the membrane unit 12 Thus, the flow rate of the permeated water W ₂₂ of the separation membrane is prevented from being reduced.

FIG. 8 is a schematic view showing an example of the exhaust gas processing system according to the fourth embodiment. As shown in FIG. 8, the exhaust gas treatment device 7 according to this embodiment, in addition to the configuration of the exhaust gas treatment apparatus 1 shown in FIG. 1, flue gas desulfurization unit 11 and the film processing in the flow direction of the desulfurization effluent W ₁₁ A mercury removing unit 16 provided between the unit 12 and the unit 12 is provided. The mercury removal unit 16 includes a separation unit 161 for solid-liquid separation of liquid mercury and solid mercury (for example, a solid compound with a mercury compound attached and contained) contained in the desulfurization drainage W ₁₁ , and a mercury processing unit 162 to remove the soluble mercury dissolved in the W _11.

The separation unit 161 is, for example, liquid mercury (for example, metal mercury Hg), solid mercury (for example, HgSO ₄ , Hg ₂ SO, etc.) contained in the desulfurization drainage W ₁₁ by coagulation sedimentation, membrane separation, sand filtration or the like. ₄ , HgS, Hg ₂ S) are separated and removed as mercury-containing sludge. In addition, the separation unit 161 supplies the desulfurization waste water W _{16 in} which the mercury is fixed and removed to the mercury processing unit 162.

Mercury processor 162, mercury liquid in the desulfurization effluent _{W 11} a (Hg ⁰⁾ is oxidized to a soluble mercury ^{(Hg 2+),} to remove the soluble mercury in the desulfurization effluent _{W 11} oxidized. Mercury processor 162 by, for instance, the addition of such a chelating agent and chelating resins as heavy metal scavenger is removed by immobilizing the solubility mercury in desulfurization effluent W _11. In this case, the mercury-treated portion 162 adjusts the pH together with the chelating agent as needed, pH adjusters such as sodium hydroxide (caustic soda: NaOH), sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl), aluminum sulfate An aggregating agent such as Al ₂ (SO ₄ ) ₃ , polyaluminum chloride, ferric chloride (FeCl ₃ ), a polymer coagulant, and an aggregating aid may be added. In addition, the mercury processing unit 162 adds a sulfide-based mercury removing agent such as iron sulfide and sodium sulfide to the desulfurization waste water W ₁₁ , and the mercury sulfide may be removed by the following reaction. (HgS) mercury may be removed by immobilizing a. immobilized mercury sulfide is flocculation, membrane separation, sand filtration, and separation excluded from desulfurization effluent W ₁₁ by such as activated carbon adsorption It can be.
Hg ²⁺ + S ^2- → Hg S ↓

In addition, the mercury-treated portion 162 is a cation exchange resin that adsorbs desorbed mercury (Hg ²⁺ ) and desorbs the desulfurization waste water W ₁₁ (eg, HgCl ₃ ⁻ , HgCl ₄ ²⁻ , HgS ₂ ^2−, etc.). by transmitting to the ion-exchange resin may be removed soluble mercury in the desulfurization waste water W _11. In addition, in the case where the reducing substance (oxidation inhibiting substance) is present, the mercury processing unit 162 adds a predetermined amount of an oxidizing agent (for example, air) to be in a predetermined oxidation state (for example, redox potential (ORP)) The value may be maintained at +100 mV or more and 200 mV or less to suppress scattering of zero-valent mercury (Hg ⁰ ) into the gas phase.

Next, the entire operation of the exhaust gas processing device 7 will be described. The desulfurization waste water W ₁₁ containing the sulfur content discharged from the flue gas desulfurization part 11 is supplied to the separation part 161 of the mercury removal part 16 via the desulfurization waste water supply line L ₁ . In the desulfurization waste water W ₁₁ supplied to the separation unit 161, solid and liquid mercury is separated and removed by coagulation sedimentation, membrane separation, sand filtration, etc., and is sent to the mercury processing part 162 as desulfurization waste water W ₁₆ after solid-liquid separation. Supplied. Soluble mercury is removed from the desulfurization waste water W ₁₆ supplied to the mercury processing unit 162 by the addition of a chelating agent (the removed mercury is not shown). The desulfurization waste water W ₁₇ from which the soluble mercury has been removed is supplied to the membrane processing unit 12. About others, since it is the same as that of exhaust gas processing device 1 shown in Drawing 1, explanation is omitted.

As described above, according to the present embodiment, solid and liquid mercury contained in the desulfurization waste water W ₁₁ discharged from the flue gas desulfurization part 11 is removed by the separation part 161 and soluble mercury is removed. Since the mercury is removed by the mercury processing unit 162, mercury adhering to the separation membrane of the membrane processing unit 12 can be reduced. Thus, it is possible to reduce the mercury adhering to the film processing section 12, since the mercury mercury concentration was reduced in the permeate W ₂₂ can be reduced to below the effluent standard value, the permeate W ₂₂ It becomes possible to release it.

Fifth Embodiment
The fifth embodiment will now be described. In the following, the components common to the first embodiment described above are denoted by the same reference numerals. Further, differences from the above-described first embodiment will be mainly described, and redundant description will be avoided.

FIG. 9A is a schematic view showing an example of an exhaust gas processing system according to the fifth embodiment. As shown in FIG. 9A, the exhaust gas treatment apparatus 8A according to this embodiment, in addition to the configuration of the exhaust gas treatment apparatus 1 shown in FIG. 1, it is branched from the concentrate water supply line L _21, desulfurization effluent supply line L ₁ a concentrated water circulation line L ₆₁ that is connected to a water quality measuring unit 17 that measures the quality of the concentrated water W ₂₁ through the concentrated water circulation line L _61, based on the quality of the concentrated water W ₂₁ measured by the quality measuring unit 17 And a control unit 18 configured to control the flow rate of the concentrated water W ₂₁ flowing through the concentrated water circulation line L ₆₁ as the circulating water W ₂₄ . The concentrated water circulation line L ₆₁ is provided with a flow control valve V ₁ for adjusting the flow rate of the circulating water W ₂₄ flowing through the concentrated water circulation line L ₆₁ . That is, in the exhaust gas treatment apparatus 8A, film processing section 12 is capable of circulating the concentrated water _{W 21} as the circulating water _{W 24} through a concentrated water circulation line _{L 61.}

The water quality measurement unit 17 measures the conductivity (EC: Electrical Conductivity) of the concentrated water W ₂₁ , etc., to thereby supply chloride ions of the concentrated water W ₂₁ supplied from the membrane processing unit 12 to the flue gas desulfurization unit 11. Estimate the concentration of the ion component.

The control unit 18 is operated using a general-purpose or dedicated computer on which a CPU (central processing unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. is mounted and a program operating on this computer . The control unit 18 estimates the chloride ion concentration in the concentrated water W ₂₁ based on the conductivity of the concentrated water W ₂₁ measured by the water quality measurement unit 17, and the circulating water W ₂₄ is circulated to the desulfurization drainage W ₁₁ The flow rate is controlled to operate such that the chloride ion concentration in the concentrated water W _{21 is} below the reference value.

When the conductivity of the concentrated water W ₂₁ exceeds the reference value, the control unit 18 increases the opening degree of the flow control valve V ₁ to increase the flow rate of the circulating water W ₂₄ circulated to the membrane processing unit 12 It works to make it Thus, the exhaust gas processing device 8A can reduce the amount of chloride ions supplied to the exhaust gas desulfurization unit 11 together with the concentrated water W ₂₁ , and the chloride discharged from the membrane processing unit 12 together with the permeated water W ₂₂ . The amount of ions can be increased. As a result, it is possible to reduce the amount of chloride ions in the exhaust gas treatment apparatus 8A, the following reference values chloride ion concentration of the desulfurization waste water W ₁₁ discharged from the desulfurization effluent, and flue gas desulfurization section 11 in the flue gas desulfurization unit 11 Therefore, it is possible to prevent the deterioration of the desulfurization performance of the flue gas desulfurization unit 11 due to the chloride ion.

In addition, when the conductivity of the concentrated water W ₂₁ becomes less than or equal to the reference value, the control unit 18 decreases the opening degree of the flow rate adjustment valve V ₁ to circulate the circulating water W ₂₄ circulated to the membrane processing unit 12. Operate to reduce the flow rate. Thereby, in the exhaust gas processing device 8A, the flow rate of the concentrated water W ₂₁ supplied from the membrane processing unit 12 to the exhaust gas desulfurization unit 11 increases, so the chloride ion concentration of the exhaust gas desulfurization unit 11 is in the range below the reference value. To increase. As a result, it is possible to operate without reducing the efficiency of the desulfurization treatment, and the amount of recovered sulfur in the flue gas desulfurization unit 11 is increased. The other configuration is the same as that of the exhaust gas processing device 1 shown in FIG.

In the example shown in FIG. 9A, an example is described of controlling the circulation amount of the measurement result based concentrated water W ₂₁ water quality concentrated water W _21, the control unit 18, measurement of the quality of the permeated water W ₂₂ The circulation amount of the concentrated water W ₂₁ circulated as the circulation water W ₂₄ may be controlled based on the result. FIG. 9B is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. In the exhaust gas treatment apparatus 8B shown in FIG. 9B, the water quality measurement unit 17, instead of the quality of the concentrated water _{W 21,} measures the quality of the permeate _{W 22.} Water measuring unit 17, by measuring the like conductivity as a quality of permeate W _22, to estimate the concentration of the ionic components such as chloride ions in the permeate water W ₂₂ discharged from the film processing section 12. The control unit 18 estimates the chloride ion concentration in the permeate water W ₂₂ based on the conductivity of the permeate water W ₂₂ measured by the water quality measurement unit 17, and the circulating water W ₂₄ is circulated to the desulfurization drainage W ₁₁ The flow rate is controlled to operate such that the chloride ion concentration in the concentrated water W _{21 is} below the reference value.

Control unit 18, when the conductivity of the permeate W ₂₂ is less than the reference value, increases the flow rate of the circulating water W ₂₄ that is recycled to the membrane unit 12 increases the opening degree of the flow control valve V ₁ To work. As a result, the exhaust gas processing device 8B can reduce the amount of chloride ions supplied to the exhaust gas desulfurization unit 11 together with the concentrated water W ₂₁ , and the chloride discharged from the membrane processing unit 12 together with the permeated water W ₂₂ . The amount of ions can be increased. As a result, the amount of chloride ions in the exhaust gas treatment apparatus 8B can be reduced, and the chloride ion concentration of the desulfurization drainage W11 in the exhaust gas desulfurization unit 11 and the desulfurization drainage W11 discharged from the exhaust gas desulfurization unit 11 is made lower than the reference value. Since it can reduce, the fall of the desulfurization performance of flue gas desulfurization part 11 by chloride ion can be prevented.

In addition, when the conductivity in the permeate water W ₂₂ exceeds the reference value, the control unit 18 reduces the opening degree of the flow rate adjustment valve V ₁ and circulates the circulation water W ₂₄ circulated to the membrane processing unit 12. Operate to reduce the flow rate. As a result, the flow rate of the concentrated water W ₂₁ supplied from the membrane processing unit 12 to the flue gas desulfurization unit 11 increases, so the chloride ion concentration of the flue gas desulfurization unit 11 is increased in the range below the reference value. As a result, it is possible to operate without reducing the efficiency of the desulfurization treatment, and the amount of recovered sulfur in the flue gas desulfurization unit 11 is increased. Desulfurization treatment of the combustion exhaust gas in the exhaust gas desulfurization unit 11 can be performed efficiently. The other configuration is the same as that of the exhaust gas processing device 8A shown in FIG. 9A, and thus the description thereof is omitted.

Further, in the example shown in FIG. 9B, an example is described of controlling the amount of circulating concentrated water W ₂₁ is circulated as circulating water W ₂₄ based on the measurement results of the quality of the permeate W _22, the control unit 18, The circulation amount of the concentrated water W ₂₁ circulated as the circulating water W ₂₄ may be controlled based on the measurement result of the water quality of the desulfurization drainage W ₁₁ . FIG. 9C is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. In the exhaust gas treatment apparatus 8C shown in FIG. 9C, the water quality measurement unit 17, instead of the quality of the permeate _{W 22,} measures the quality of desulfurization effluent _{W 11.} Water measuring unit 17, by measuring the like conductivity as a quality of desulfurization effluent W _11, to estimate the concentration of the ionic components such as chloride ions in the desulfurization effluent W ₁₁ discharged from the flue gas desulfurization unit 11. The control unit 18 controls the flow rate of the circulating water W ₂₄ to be circulated to the desulfurization drainage W ₁₁ based on the conductivity of the desulfurization drainage W ₁₁ measured by the water quality measurement unit 17, and chlorides in the concentrated water W ₂₁ It operates so that the ion concentration is below the reference value.

Control unit 18, when the conductivity in the desulfurization effluent W ₁₁ is less than the reference value, reduces the flow rate of the circulating water W ₂₄ which reduces the opening degree of the flow control valve V ₁ is circulated in the film processing section 12 It works to make it Thereby, in the exhaust gas processing device 8C, the flow rate of the concentrated water W ₂₁ supplied from the membrane processing unit 12 to the exhaust gas desulfurization unit 11 increases, so the chloride ion concentration of the exhaust gas desulfurization unit 11 is in the range below the reference value. To increase. As a result, it is possible to operate without reducing the efficiency of the desulfurization treatment, and the amount of recovered sulfur in the flue gas desulfurization unit 11 is increased.

Further, when the conductivity in the desulfurization drainage W ₁₁ exceeds the reference value, the control unit 18 increases the opening degree of the flow rate adjustment valve V ₁ to circulate the concentrated water W ₂₁ that is circulated to the membrane processing unit 12. Operate to increase the flow rate. As a result, the exhaust gas processing device 8C can reduce the amount of chloride ions supplied to the exhaust gas desulfurization unit 11 together with the concentrated water W ₂₁ , and the chloride discharged from the membrane processing unit 12 together with the permeated water W ₂₂ . The amount of ions can be increased. As a result, since the chloride ion concentration in the concentrated water W ₂₁ can be reduced below the reference value, lowering of desulfurization performance in the desulfurization unit 11 by chloride ions fed to the flue gas desulfurization unit 11 together with the concentrated water W ₂₁ You can prevent. The other configuration is the same as that of the exhaust gas processing device 8A shown in FIG. 9A, and thus the description thereof is omitted.

In the example shown in FIGS. 9A to 9C, the concentrated water W ₂₁ of the membrane processing unit 12 is provided by providing a concentrated water circulation line L ₆₁ branched from the concentrated water supply line L ₂₁ and connected to the desulfurization waste water supply line L _1. an example has been described for circulating the circulating water W _24, may be circulated permeate W ₂₂ discharged from the film processing section 12 as the circulating water. FIG. 9D is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. In the exhaust gas treatment apparatus 8D shown in FIG. 9D, instead of the concentrated water circulation line L ₆₁ of the exhaust gas treatment apparatus 8A shown in FIG. 9A, transmission provided between the permeate discharge line L ₂₂ and desulfurization effluent supply line L ₁ A water circulation line L ₆₂ is provided. The permeated water circulation line L ₆₂ supplies the permeated water W ₂₂ discharged from the membrane processing unit 12 to the desulfurization drainage W ₁₁ supplied to the membrane processing unit 12 as circulating water W ₂₅ . The permeated water circulation line L ₆₂ is provided with a flow control valve V ₂ that controls the flow rate of circulating water W ₂₅ flowing through the permeated water circulation line L ₆₂ . The control unit 18 estimates the chloride ion concentration in the permeate W ₂₂ based on the conductivity of the concentrated water W ₂₁ measured by the water quality measurement unit 17, and the circulating water W ₂₅ is circulated to the desulfurization drainage W ₁₁ The flow rate is controlled to make the chloride ion concentration in the concentrated water W ₂₁ equal to or less than the reference value.

When the conductivity in the concentrated water W ₂₁ exceeds the reference value, the control unit 18 increases the opening degree of the flow rate adjustment valve V ₂ to set the flow rate of the circulating water W ₂₅ circulated to the membrane processing unit 12. Operate to increase. Thus, the exhaust gas processing device. 8D, it is possible to dilute the desulfurization effluent W ₁₁ to be supplied to the film processing section 12, it is possible to reduce the chloride ion concentration in the concentrated water W ₂₁ below the reference value, ejection with concentrated water W ₂₁ It is possible to prevent the desulfurization performance of the flue gas desulfurization unit 11 from being degraded by chloride ions supplied to the smoke desulfurization unit 11.

Further, when the conductivity in the concentrated water W ₂₁ becomes equal to or less than the reference value, the control unit 18 reduces the opening degree of the flow rate adjustment valve V ₂ and circulates the circulating water W ₂₅ circulated to the membrane processing unit 12. Operate to reduce the flow rate of Thus, the exhaust gas processing device. 8D, it is possible to increase the amount of chloride ions that are discharged with the permeate W ₂₂ from the membrane unit 12, the flow rate of the concentrated water W ₂₁ to be supplied to the flue gas desulfurization unit 11 Since the chloride ion concentration of the flue gas desulfurization unit 11 can be operated within the range below the reference value, the efficiency of the desulfurization treatment is not reduced, and the amount of recovered sulfur in the flue gas desulfurization unit 11 is Increase. The other configuration is the same as that of the exhaust gas processing device 8A shown in FIG. 9A, and thus the description thereof is omitted.

In the example illustrated in FIG. 9D, an example of controlling the circulation amount of the permeate water W ₂₂ circulated as the circulation water W ₂₅ based on the measurement result of the water quality of the concentrate W ₂₁ has been described. the circulation amount of the permeate W ₂₂ is circulated as circulating water W ₂₅ based on the measurement results of the quality of the permeate W ₂₂ may be controlled. FIG. 9E is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. In the exhaust gas treatment apparatus 8E shown in FIG. 9E, the water quality measurement unit 17, instead of the quality of the concentrated water _{W 21,} measures the quality of the permeate _{W 22.} Water measuring unit 17, by measuring the like conductivity of the permeate W _22, to estimate the concentration of the ionic components such as chloride ions in the permeate water W ₂₂ discharged from the film processing section 12. Control unit 18, by adjusting the opening of flow control valve V ₂ on the basis of the conductivity of the water quality measurement part 17 permeate W ₂₂ measured by the flow rate of circulation water W ₂₅ circulating in the desulfurization effluent W ₁₁ To control the chloride ion concentration in the permeate water W ₂₂ to be equal to or lower than the reference value.

The control unit 18 decreases the opening degree of the flow rate adjusting valve V ₂ when the conductivity in the permeate water W ₂₂ becomes less than or equal to the reference value, and the flow rate of the circulating water W ₂₅ circulated to the membrane processing unit 12 Work to reduce Thus, the exhaust gas processing device. 8E, it is possible to increase the amount of chloride ions that are discharged with the permeate W ₂₂ from the membrane unit 12, the flow rate of the concentrated water W ₂₁ to be supplied to the flue gas desulfurization unit 11 Since the chloride ion concentration of the flue gas desulfurization unit 11 can be operated within the range below the reference value, the efficiency of the desulfurization treatment is not reduced, and the amount of recovered sulfur in the flue gas desulfurization unit 11 is Increase.

In addition, when the conductivity in the permeate water W ₂₂ exceeds the reference value, the control unit 18 increases the opening degree of the flow rate adjustment valve V ₂ to circulate the circulating water W ₂₅ circulated to the membrane processing unit 12. Operate to increase the flow rate. Thus, the exhaust gas processing device. 8E, it is possible to dilute the desulfurization effluent W ₁₁ to be supplied to the film processing section 12, it is possible to reduce the chloride ion concentration in the concentrated water W ₂₁ below the reference value, ejection with concentrated water W ₂₁ It is possible to prevent the desulfurization performance of the flue gas desulfurization unit 11 from being degraded by chloride ions supplied to the smoke desulfurization unit 11. The other configuration is the same as that of the exhaust gas processing device 8A shown in FIG.

In the example illustrated in FIG. 9E, an example is described in which the circulation amount of the permeate water W ₂₂ circulated as the circulation water W ₂₅ is controlled based on the measurement result of the water quality of the concentrate W ₂₁ . the circulation amount of the permeate W ₂₂ is circulated as circulating water W ₂₅ based on the measurement results of the quality of the permeate W ₂₂ may be controlled. FIG. 9F is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. In the exhaust gas treatment apparatus 8F shown in FIG. 9F, the water quality measurement unit 17, instead of the quality of the permeate _{W 22,} measures the quality of desulfurization effluent _{W 11.} Water measuring unit 17, by measuring the like conductivity of desulfurization effluent W _11, to estimate the concentration of the ionic components such as chloride ions in the desulfurization effluent W ₁₁ to be supplied to the film processing section 12. Control unit 18, by adjusting the opening of flow control valve V ₂ on the basis of the conductivity of the desulfurization effluent W ₁₁ measured by the quality measuring unit 17, the flow rate of circulation water W ₂₅ circulating in the desulfurization effluent W ₁₁ To control the chloride ion concentration in the permeate water W ₂₂ to be equal to or lower than the reference value.

When the conductivity in the desulfurization waste water W ₁₁ exceeds the reference value, the control unit 18 increases the opening degree of the flow rate adjustment valve V ₂ and sets the flow rate of the circulating water W ₂₅ circulated to the membrane processing unit 12 Operate to increase. Thus, the exhaust gas processing device. 8F, it is possible to dilute the desulfurization effluent W ₁₁ to be supplied to the film processing section 12, it is possible to reduce the chloride ion concentration in the concentrated water W ₂₁ below the reference value, ejection with concentrated water W ₂₁ It is possible to prevent the desulfurization performance of the flue gas desulfurization unit 11 from being degraded by chloride ions supplied to the smoke desulfurization unit 11.

The control unit 18, when the conductivity in the permeate W ₂₂ is equal to or less than the reference value, circulating water W ₂₅ that is recycled to the membrane unit 12 decreases the opening degree of the flow control valve V ₂ Operate to reduce the flow rate of Thus, the exhaust gas processing device. 8E, it is possible to increase the amount of chloride ions that are discharged with the permeate W ₂₂ from the membrane unit 12, the flow rate of the concentrated water W ₂₁ to be supplied to the flue gas desulfurization unit 11 Since the chloride ion concentration of the flue gas desulfurization unit 11 can be increased within the range below the reference value, the desulfurization treatment efficiency is not reduced, and the sulfur content in the flue gas desulfurization unit 11 is reduced. Recovery volume increases. The other configuration is the same as that of the exhaust gas processing device 8A shown in FIG.

As described above, according to the present embodiment, the concentrated water W ₂₁ flowing through the concentrated water supply line L ₂₁ , the permeated water W ₂₂ discharged from the membrane processing unit 12, and the desulfurization drainage supplied to the membrane processing unit 12 based on at least one quality of W _11, for controlling at least one of flow rate of the circulating water W concentrated water is circulated as a ₂₅ W ₂₁ and permeate W ₂₂ in film processing section 12. Flue gas by this exhaust gas treatment apparatus 8A ~ 8F, since it is possible to control the chloride ion concentration in the concentrated water W ₂₁ supplied from the film processing section 12 to the flue gas desulfurization unit 11, together with the concentrated water W ₂₁ The deterioration of the desulfurization performance based on the chloride ion supplied to the desulfurization unit 11 can be prevented.

Further, in the embodiment described above, the configuration in which the membrane processing unit 12 circulates the concentrated water W ₂₁ or the permeated water W ₂₂ as the circulating water W ₂₅ via the concentrated water circulation line L ₆₁ or the permeated water circulation line L ₆₂ is described. but the may be a bypass line is provided to bypass the desulfurization effluent W ₁₁ to permeate W ₂₂ between the desulfurization effluent supply line L ₁ and the permeate discharge line L _22. FIG. 9G is a schematic view showing an example of an exhaust gas processing system according to the fifth embodiment. As illustrated in FIG. 9G, the exhaust gas treatment apparatus 8G according to the present embodiment, in addition to the configuration of the exhaust gas treatment apparatus 1 shown in FIG. 1, is branched from the desulfurization effluent supply line L _1, the permeate discharge line L ₂₂ a bypass line L ₆₃ that is connected to a water quality measuring unit 17 that measures the quality of the concentrated water W ₂₁ through the concentrated water circulation line L _61, based on the quality of the concentrated water W ₂₁ measured by the quality measuring unit 17, and a control unit 18 for controlling at least part of the flow rate of the desulfurization waste water _{W 11} flowing through the bypass line _{L 63} as a bypass water _{W 26.} The bypass line L ₆₃ is provided with a flow control valve V ₃ for adjusting the flow rate of the bypass water W ₂₆ flowing through the bypass line L ₆₃ . That is, in the exhaust gas treatment apparatus 8G, at least a portion of the desulfurization effluent W11 can be supplied to the permeate W ₂₂ via the bypass line L ₆₃ without being membrane separation by membrane treatment unit 12.

Water measuring unit 17, by measuring the like conductivity of the concentrated water W _21, estimate the concentration of the ionic components such as chloride ion concentrated water W ₂₁ supplied from the film processing section 12 to the flue gas desulfurization unit 11 Do. Control unit 18, based on the conductivity of the concentrated water W ₂₁ measured by the quality measuring unit 17, and estimate the chloride ion concentration in the concentrated water W _21, is supplied as a bypass water W ₂₆ to permeate W ₂₂ that by controlling the flow rate of the desulfurization effluent W _11, it operates to the chloride ion concentration in the concentrated water W ₂₁ to equal to or less than the reference value.

When the conductivity of the concentrated water W ₂₁ exceeds the reference value, the control unit 18 increases the opening degree of the flow control valve V ₃ to increase the flow rate of the bypass water W ₂₆ supplied to the permeate water W _22. It works to make it Thus, the exhaust gas processing device 8G can reduce the amount of chloride ions supplied to the exhaust gas desulfurization unit 11 together with the concentrated water W ₂₁ , and the chloride discharged from the membrane processing unit 12 together with the permeated water W ₂₂ . The amount of ions can be increased. As a result, the amount of chloride ions in the exhaust gas treatment apparatus 8G can be reduced, and the chloride ion concentration of the desulfurization drainage W ₁₁ discharged from the desulfurization drainage and the flue gas desulfurization unit 11 in the exhaust gas desulfurization unit 11 is below the reference value. Therefore, it is possible to prevent the deterioration of the desulfurization performance of the flue gas desulfurization section 11 due to chloride ions.

Further, when the conductivity of the concentrated water W ₂₁ becomes equal to or lower than the reference value, the control unit 18 decreases the opening degree of the flow rate adjustment valve V ₁ and supplies the bypass water W ₂₆ to the permeate water W ₂₂ . Operate to reduce the flow rate. Thereby, in the exhaust gas processing device 8G, the flow rate of the concentrated water W ₂₁ supplied from the membrane processing unit 12 to the exhaust gas desulfurization unit 11 increases, so the chloride ion concentration of the exhaust gas desulfurization unit 11 is in the range below the reference value. To increase. As a result, it is possible to operate without reducing the efficiency of the desulfurization treatment, and the amount of recovered sulfur in the flue gas desulfurization unit 11 is increased. The other configuration is the same as that of the exhaust gas processing device 1 shown in FIG.

In the example shown in FIG. 9G, an example is described of controlling the circulation amount of the measurement result based concentrated water W ₂₁ water quality concentrated water W _21, the control unit 18, measurement of the quality of the permeated water W ₂₂ it may control the supply amount of permeate W ₂₂ desulfurization effluent W ₁₁ supplied to the bypass water W ₂₆ on the basis of the results. FIG. 9H is a schematic view showing another example of the exhaust gas processing system according to the fifth embodiment. In the exhaust gas treatment apparatus 8H shown in FIG. 9H, water quality measurement unit 17, instead of the quality of the concentrated water _{W 21,} measures the quality of the permeate _{W 22.} Water measuring unit 17, by measuring the like conductivity as a quality of permeate W _22, to estimate the concentration of the ionic components such as chloride ions in the permeate water W ₂₂ discharged from the film processing section 12. The control unit 18 estimates the chloride ion concentration in the permeate water W ₂₂ based on the conductivity of the permeate water W ₂₂ measured by the water quality measurement unit 17, and is supplied to the permeate water W ₂₂ as bypass water W _26. that by controlling the flow rate of the desulfurization effluent W _11, it operates to the chloride ion concentration in the concentrated water W ₂₁ to equal to or less than the reference value.

Control unit 18, when the conductivity of the permeate W ₂₂ is less than the reference value, increases the flow rate of the bypass water W ₂₆ to be supplied to the permeate W ₂₂ increases the opening degree of the flow regulating valve V ₃ To work. Thus, the exhaust gas processing device 8H can reduce the amount of chloride ions supplied to the exhaust gas desulfurization unit 11 together with the concentrated water W ₂₁ , and the chloride discharged from the membrane processing unit 12 together with the permeated water W ₂₂ . The amount of ions can be increased. As a result, it is possible to reduce the amount of chloride ions in the exhaust gas treatment apparatus 8H, below the reference value of the chloride ion concentration in the desulfurization effluent W ₁₁ discharged from the desulfurization effluent, and flue gas desulfurization section 11 in the flue gas desulfurization unit 11 Therefore, it is possible to prevent the deterioration of the desulfurization performance of the flue gas desulfurization unit 11 due to the chloride ion.

The control unit 18, when the conductivity in the permeate W ₂₂ exceeds the reference value, the bypass water W ₂₂ to be supplied to the permeate W ₂₂ reduces the opening of flow control valve V ₃ Operate to reduce the flow rate. Thus, the flow rate of the desulfurization waste water W ₁₁ to be supplied to the permeate W ₂₂ is increased, the chloride ion concentration in the flue gas desulfurization unit 11 is increased in the range of less than the reference value. As a result, it is possible to operate without reducing the efficiency of the desulfurization treatment, and the amount of recovered sulfur in the flue gas desulfurization unit 11 is increased. Desulfurization treatment of the combustion exhaust gas in the exhaust gas desulfurization unit 11 can be performed efficiently. The other configuration is the same as that of the exhaust gas processing device 8A shown in FIG. 9A, and thus the description thereof is omitted.

In the embodiment described above, an example of estimating the concentration of chloride ion of the concentrated water W ₂₁ and the permeated water W ₂₂ based on the conductivity was described, but the water quality of the concentrated water W ₂₁ and the permeated water W ₂₂ is The determination may be made by providing a predetermined reference value based on analysis values of various chemical analysis.

Further, in the above embodiment, an example is described of controlling the amount of chloride ions fed to the flue gas desulfurization unit 11 by adjusting the amount of circulating concentrated water W ₂₁ and permeate W _22, desulfurization The amount of chloride ions supplied to the flue gas desulfurization unit 11 may be controlled by increasing the chloride ion permeability coefficient of the separation membrane by heating the drainage W ₁₁ and adjusting the pH.

In the example shown in FIGS. 9D to 9F, as the membrane processing unit 12, one in which a plurality of membrane separation units are disposed in a pressure vessel may be used. FIG. 10 is a view showing an example of a film processing unit according to the present embodiment. The membrane processing unit 12 shown in FIG. 10 includes a plurality of (seven in the present embodiment) first to seventh membrane separation units 12-1 to 12-7 disposed in a pressure vessel (vessel) 120. Equipped with The first membrane separation unit 12-1 to seventh membrane separation unit 12-7 includes a separation membrane 12a which membrane separates the desulfurization effluent _{W 11} to the concentrated water _{W 21} and permeate _{W 22.} The pressure vessel 120 includes a desulfurization effluent inlet pipe 1201 for introducing the desulfurization effluent _{W 11} to the pressure vessel 120, the desulfurization effluent discharge pipe 1202 for discharging the desulfurization effluent _{W 11} from the pressure vessel 120, a first membrane separation unit 12 And a water collecting pipe 1203 connecting the first to seventh membrane separation units 12-7 in series. Water collecting pipe 1203, a permeate _{W 22} which is membrane separated by the first membrane separation unit 12-1 to seventh membrane separation unit 12-7 for collecting. Further, the water collection pipe 1203 and the upstream side water collection pipe 1203 b on the upstream side (hereinafter, also simply referred to as “upstream side”) in the flow direction of the desulfurization drainage W ₁₁ flowing in the pressure vessel 120 It is divided into a downstream side water collection pipe 1203 c on the downstream side (hereinafter, also simply referred to as “downstream side”). As the first membrane separation unit 12-1 to the seventh membrane separation unit 12-7, for example, one end side of the separation membrane 12a is communicated with the water collection pipe 1203, and is wound via a mesh spacer (not shown) One provided with a spiral separation membrane is used.

Film processing section 12, the desulfurization effluent _{W 11} introduced into the pressure vessel 120 through the desulfurization effluent supply line _{L 1} and the desulfurization effluent inlet tube 1201, first membrane separation unit 12-1 to seventh membrane separation unit 12 The membrane is separated into concentrated water W _{21 in} which the sulfate ion is concentrated and permeate water W ₂₂ in which the sulfate ion is removed by the separation membrane 12 a of −7. Further, the membrane processing unit 12 supplies the concentrated water W ₂₁ to the exhaust gas desulfurization unit 11 through the desulfurization drainage discharge pipe 1202 and the concentrated water supply line L ₂₁ . Film processing section 12 condenses water first membrane separation unit 12-1 to seventh membrane separation unit 12-7 permeate _{W 22} which is membrane separation in the water collecting pipe 1203. In addition, the membrane processing unit 12 uses the permeated water W _22-1 discharged from the downstream side of the membrane processing unit 12 via the downstream side water collection pipe 1203b by the partition 1203a of the water collection pipe 1203 with the collected water W ₂₂ , And permeated water W _22-2 discharged from the upstream side. Further, the membrane processing unit 12 discharges the permeated water W _22-1 from the downstream side of the membrane processing unit 12 to the outside through the permeated water discharge line L _{22-1 and, at the same time,} passes the permeated water discharge line L _22-2 . The permeate water W _22-2 is discharged from the upstream side of the membrane processing unit 12 to the outside. The permeate water W _22-2 discharged from the upstream side of the membrane processing unit 12 has a chloride ion concentration lower than that of the permeate water W _22-1 discharged from the downstream side.

The first membrane separation unit 12-1 is provided on the side of the desulfurization drainage introduction pipe 1201 in the pressure vessel 120. The second membrane separation unit 12-2 connected to the first membrane separation unit 12-1 by the upstream water collection pipe 1203c is provided at the rear stage of the first membrane separation unit 12-1. The third membrane separation unit 12-3 connected to the second membrane separation unit 12-2 by the upstream water collection pipe 1203c is provided at the rear stage of the second membrane separation unit 12-2. The fourth membrane separation unit 12-3 is connected to the third membrane separation unit 12-3 by a water collection pipe 1203 that is divided into an upstream water collection pipe 1203c and a downstream water collection pipe 1203b via a partition wall 1203a at the rear stage of the third membrane separation unit 12-3. A membrane separation unit 12-4 is provided. The fifth membrane separation unit 12-5 connected to the fourth membrane separation unit 12-4 by the downstream water collection pipe 1203b is provided at the rear stage of the fourth membrane separation unit 12-4. The sixth membrane separation portion 12-6 connected to the fifth membrane separation portion 12-5 by the downstream side water collection pipe 1203b is provided at the rear stage of the fifth membrane separation portion 12-5. A seventh membrane separation unit 12-7 is provided downstream of the sixth membrane separation unit 12-6, and is connected to the sixth membrane separation unit 12-6 by a downstream side water collection pipe 1203b.

That is, in the membrane processing unit 12, the membrane separation unit 12-1 to the membrane separation unit 12-3 are provided on the upstream side of the partition 1203 a in the water collection tube 1203, and the membrane separation unit on the downstream side of the partition 1203 a in the pressure vessel 120 12-4 to a membrane separation unit 12-7, and a plurality of first to seventh membrane separation units 12-1 to 12-7 including a first separation film 12a are connected in series by a water collection pipe 1203; There is. Here, connection in series means that the concentrated water W _{21 that} has been subjected to membrane separation by the first membrane separation unit 12-1 to the sixth membrane separation unit 12-6 on the upstream side of the membrane processing unit 12 The first membrane separation unit 12-1 is supplied to the second membrane separation unit 12-6 to the seventh membrane separation unit 12-7 of the next stage via the first membrane separation unit 12-1 to the sixth membrane separation unit 12-6. The permeated water W ₂₂ subjected to membrane separation in the section 12-1 to the third membrane separation section 12-3 is discharged to the outside of the membrane processing section 12 as the permeate water W _22-2 through the upstream water collection pipe 1203c. The permeated water W ₂₂ membrane-separated by the fourth membrane separation unit 12-4 to the seventh membrane separation unit 12-7 is transmitted to the outside of the membrane processing unit 12 as the permeated water W _22-1 through the downstream water collection pipe 1203 b. It is a drained connection. Thus, the membrane processing unit 12 desulfurizes the desulfurization waste water into the highly concentrated concentrated water W ₂₁ in which the sulfate ions in the desulfurization waste water W ₁₁ are sequentially concentrated and the permeate water W ₂₂ in which the sulfate ions in the desulfurization waste water W ₁₁ are removed. the W ₁₁ is possible membrane separation, it is classified permeate _{W 22} in the _{W 22-2} discharged from the downstream side of the permeate _{W 22 - 1} and the pressure vessel 120 to be discharged from the upstream side of the pressure vessel 120 it can. As a result, the membrane processing unit 12 can supply the concentrated water W _{21 in} which sulfate ions are concentrated to a high concentration to the flue gas desulfurization unit 11, and the permeate water W _{22-1 in} which the chloride ion concentration mutually differs , W _22-2 can be supplied to the desulfurization waste water W ₁₁ , respectively.

As the separation membrane 12a, the same one as the separation membrane of the first embodiment can be used. Further, as the separation membrane 12a, the same separation membrane 12a may be used in the seven first membrane separation parts 12-1 to the seventh membrane separation parts 12-7, or different separation membranes 12a may be used. .

The first membrane separation unit 12-1 performs membrane separation of the desulfurization drainage W ₁₁ into concentrated water W ₂₁ and permeate water W _22-2 (W ₂₂ ). Further, the first membrane separation unit 12-1 supplies the concentrated water W ₂₁ obtained by the membrane separation to the second membrane separation unit 12-2. The first membrane separation unit 12-1, membrane permeate _{W 22-2} obtained by the separation, the upstream side of the upstream water collecting pipe 1203c and permeate discharge line _{L 22-2} through the film processing section 12 Are discharged to the outside of the membrane processing unit 12.

The second membrane separation unit 12-2 membrane separation in the concentrated water _{W 21} supplied from the first membrane separation unit 12-1 and concentrated water _{W 21} and permeate _{_W} 22-2 _{_(W 22).} Further, the second membrane separation unit 12-2 supplies the concentrated water W ₂₁ to the third membrane separation unit 12-3. In addition, the second membrane separation unit 12-2 moves the permeated water W _22-2 obtained by the membrane separation upstream of the membrane processing unit 12 via the upstream water collection pipe 1203c and the permeated water discharge line L _22-2. Are discharged to the outside of the membrane processing unit 12.

The third membrane separation unit 12-3 membrane separation in the concentrated water _{W 21} supplied from the second membrane separation unit 12-2 and the concentrated water _{W 21} and permeate _{_W} 22-2 _{_(W 22).} In addition, the third membrane separation unit 12-3 supplies the concentrated water W ₂₁ to the fourth membrane separation unit 12-4. In addition, the third membrane separation unit 12-3 moves the permeated water W _22-2 obtained by the membrane separation upstream of the membrane processing unit 12 via the upstream water collection pipe 1203c and the permeated water discharge line L _22-2. From the membrane processing unit 12.

The fourth membrane separation unit 12-4 membrane separation in the third film supplied with concentrated water _{W 21} from the separation unit 12-3 and the concentrated water _{W 21} permeate _{_W} 22-1 _{_(W 22).} Further, the fourth membrane separation unit 12-4 supplies the concentrated water W ₂₁ obtained by the membrane separation to the fifth membrane separation unit 12-5. In addition, the fourth membrane separation unit 12-4 passes the permeated water W _22-1 obtained by the membrane separation to the downstream side of the membrane processing unit 12 via the downstream water collection pipe 1203b and the permeated water discharge line L _22-1. Are discharged to the outside of the membrane processing unit 12.

Fifth membrane separation unit 12-5 is membrane separation in the fourth membrane separation unit 12-4 concentrated water _{W 21} supplied from the concentrated water _{W 21} permeate _{_W} 22-1 _{_(W 22).} In addition, the fifth membrane separation unit 12-5 supplies the concentrated water W ₂₁ obtained by the membrane separation to the sixth membrane separation unit 12-6. Further, the fifth membrane separation unit 12-5 is a downstream side of the membrane processing unit 12 through the downstream water collection pipe 1203b and the permeated water discharge line L _22-1 for the permeated water W _22-1 obtained by the membrane separation. Are discharged to the outside of the membrane processing unit 12.

Sixth membrane separation unit 12-6, membrane separated the concentrated water _{W 21} supplied from the fifth membrane separation unit 12-5 concentrated water _{W 21} and permeate _{_W} 22-1 _{_(W 22).} In addition, the sixth membrane separation unit 12-6 supplies the concentrated water W ₂₁ obtained by the membrane separation to the seventh membrane separation unit 12-7. In addition, the sixth membrane separation unit 12-6 is a downstream side of the membrane processing unit 12 through the downstream water collection pipe 1203b and the permeated water discharge line L _22-1 for the permeated water W _22-1 obtained by the membrane separation. Are discharged to the outside of the membrane processing unit 12.

The seventh membrane separation unit 12-7 performs membrane separation of the concentrated water W ₂₁ supplied from the sixth membrane separation unit 12-6 into concentrated water W ₂₁ and permeate water W _22-1 (W ₂₂ ). The seventh membrane separation unit 12-7 supplies the concentrated water _{W 21} obtained by the membrane separation in the flue gas desulfurization unit 11 through the concentrated water supply line _{L 21.} In addition, the seventh membrane separation unit 12-7 is a downstream side of the membrane processing unit 12 through the downstream water collection pipe 1203b and the permeated water discharge line L _22-1 for the permeated water W _22-1 obtained by the membrane separation. Are discharged to the outside of the membrane processing unit 12.

The permeated water discharge line L _22-1 is connected to the permeated water discharge line L ₂₂ . Between the permeate discharge line _{L 22 - 1} and the desulfurization effluent supply line _{L 1,} the permeate circulation line _{L 62} is connected. The permeated water discharge line L _22-2 is connected to the permeated water circulation line L ₆₂ . Between a connection point _{P 2} between the connection point _{P 1} of the permeate discharge line _{L 22 - 1} and the permeated water discharge line _{L 22 - 1} in the permeate circulation line _{L 62,} permeate through the permeate circulation line _{L 62} A flow rate adjusting valve V _2A is provided to adjust the flow rate of W _22-1 . Between the connection point _{P 3} and the connection point _{P 2} and the desulfurization effluent supply line _{L 1} of the permeate discharge line _{L 22-2} in the permeate circulation line _{L 62,} the circulating water flowing in the permeate circulation line _{L 62} flow control valve V ₂ to adjust the flow rate of the W ₂₅ is provided. The flow control valves V ₂ and V _2A are controlled in their opening degree by the control unit 18 (see FIG. 9A). With such a configuration, the permeated water W _22-1 discharged from the downstream side of the membrane processing apparatus 12 is supplied as desulfurized drainage as circulating water W ₂₅ through the permeated water discharge line L _22-1 and the permeated water circulation line L _62. and it can be supplied to the desulfurization effluent _{W 11} through the line _{L 1.} Further, the permeated water W _22-2 discharged from the upstream side of the membrane processing apparatus 12 passes through the permeated water discharge line L _22-2 and the permeated water circulation line L ₆₂ as the circulating water W ₂₅ through the desulfurization drainage supply line L ₁ . which can be supplied to the desulfurization wastewater W ₁₁ flowing.

Next, the operation of the film processing unit 12 according to the present embodiment will be described. FGD unit 11 desulfurized supplied to the membrane unit 12 drained from W ₁₁ are sequentially film separated by the first membrane separation unit 12-1 to seventh membrane separation unit 12-7, concentrated sulfate ions at a high concentration The membrane is separated into the concentrated water W ₂₁ and the permeated water W _22-1 and W _22-2 from which the sulfate ion has been removed. The membrane-separated concentrated water W ₂₁ is supplied to the flue gas desulfurization unit 11 through the concentrated water supply line L ₂₁ , and the membrane-separated permeated water W _22-1 and W _22-2 is the permeated water discharge line L _22-1 and L _22-2 are discharged to the outside of the membrane separation unit 12.

When the permeate water W _22-1 and W _22-2 are not circulated to the desulfurization drainage W ₁₁ as the circulating water W ₂₅ , the control unit 18 increases the opening degree of the flow rate adjustment valve V _2A and the flow rate adjustment valve V Close ₂ As a result, the permeate waters W _22-1 and W _22-2 are discharged as permeate water through the permeate water discharge lines L ₂₂ , L _22-1 and L _22-2 and the permeate water circulation line L ₆₂ .

When circulating the permeate water W _22-1 and W _22-2 as the circulating water W ₂₅ to the desulfurization drainage W ₁₁ , the control unit 18 increases the opening degree of the flow control valves V ₂ and V _2A . As a result, the permeate water W _22-1 and W _22-2 having a lower concentration of chloride ions than the desulfurization waste water W ₁₁ passes through the permeate water discharge line L _22-1 and L _22-2 and the permeate water circulation line L ₆₂ . since supplied to the desulfurization effluent W ₁₁ Te, it is possible to reduce the concentration of chloride ions in the desulfurization effluent W _11.

When circulating water W _22-2 as circulating water W ₂₅ to desulfurization drainage W ₁₁ , control unit 18 decreases the opening degree of flow rate adjustment valve V _2A and opens the opening degree of flow rate adjustment valve V ₂ Increase. Thus, the concentration of chloride ions is lower permeate _{W 22-2} is supplied to the desulfurization effluent _{W 11} via the permeate discharge line _{L 22-2} and permeate circulation line _{L 62} with respect to permeate _{W 22 - 1} Runode, the concentration of chloride ions in the desulfurization waste water W ₁₁ becomes possible to efficiently reduce. The other operations are the same as those of the exhaust gas processing devices 8D to 8F shown in FIGS. 9D to 9F, and therefore the description thereof is omitted.

As described above, according to the membrane processing unit 12 shown in FIG. 10, the concentrated water W 21 sequentially condensed by the seven first membrane separation units 12-1 to the seventh membrane separation unit 12-7 is In addition to the supply, it is possible to supply the desulfurization drainage ₁₁ with at least one of the permeate waters W _22-1 and W _22-2 having mutually different chloride ion concentrations. Thereby, for example, when the chloride ion concentration in the desulfurization waste water ₁₁ is high, the desulfurization waste water W ₁₁ is efficiently diluted with the permeate water W _22-2 having a chloride ion concentration lower than that of the permeate water W _22-1. Is also possible.

Sixth Embodiment
Next, a sixth embodiment will be described. In the following, the components common to the first embodiment described above are denoted by the same reference numerals. Further, differences from the above-described first embodiment will be mainly described, and redundant description will be avoided.

FIG. 11A is a schematic view showing an example of an exhaust gas processing system according to a sixth embodiment. As shown in FIG. 11A, in addition to the configuration of the exhaust gas processing apparatus 1 shown in FIG. 1, the exhaust gas processing apparatus 9A includes an evaporation processing unit 19 provided downstream of the film processing unit 12. The evaporation processing unit 19 evaporates water from the permeated water W ₂₂ supplied from the membrane processing unit 12 through the permeated water discharge line L ₂₂ to obtain a vapor, and a concentrated liquid and solidified salt in which a soluble substance is concentrated Get The evaporation processing unit 19 is not particularly limited as long as it can evaporate the water in the permeate water W _22. For example, various spray dryers such as a waste water spray dryer (WSD), various crystallizers, etc. It can be used. As the evaporation section 19, when it is not necessary to completely evaporate moisture from the permeate W _22, it may be used evaporative concentrator.

FIG. 11B is a schematic view showing another example of the exhaust gas processing system according to the sixth embodiment. As shown in FIG. 11B, in addition to the configuration of the exhaust gas processing device 2 shown in FIG. 3, the exhaust gas processing device 9B includes an evaporation processing unit 19 provided downstream of the second film processing unit 122. The evaporation processing unit 19 evaporates water from the concentrated water W ₃₁ supplied from the second membrane processing unit 122 via the concentrated water discharge line L ₃₁ to obtain a vapor, and also a concentrated liquid in which a soluble substance is concentrated, Obtain a solidified salt. As the evaporation processing part 19, the thing similar to what was shown to FIG. 11A can be used.

FIG. 12A is a schematic view showing another example of the exhaust gas processing system according to the sixth embodiment. As shown in FIG. 12A, in addition to the configuration of the exhaust gas processing apparatus 1 shown in FIG. 1, the exhaust gas processing apparatus 10A includes a post-processing unit 20 provided downstream of the membrane processing unit 12. The post-processing unit 20 solidifies impurities by adding alkali such as lime, lime, cement, various chemicals, etc. to the permeated water W ₂₂ supplied from the membrane processing unit 12 through the permeated water discharge line L _22. . Further, the post-processing unit 20 discharges the aftertreatment water W ₇ to remove the impurities through the post-processing water discharge line L _7. Here, the post-processing unit 20 may remove impurities such as harmful heavy metals contained in the permeate water W ₂₂ by ion exchange treatment using an ion exchange resin, chelate treatment using a chelate resin, or the like. By providing a post-processing unit 20 to remove impurities such in permeate W _22, it is possible to discharge to remove impurities in the permeate W _22.

In the post-processing unit 20, by using various chelating resins such as chelates for mercury adsorption resin and selenium (Se) adsorption chelate resin, it is also possible to remove mercury and selenium in the post-processing water W _7. As the chelate resin for mercury adsorption, for example, trade name: Epolas (registered trademark), model number: Z-7, Z-100 and the like are used. As a chelate resin for selenium adsorption, trade name: Epolas (registered trademark), model number: SE-3, AS-4 and the like are used.

FIG. 12B is a schematic view showing another example of the exhaust gas processing system according to the sixth embodiment. As shown in FIG. 12B, in addition to the configuration of the exhaust gas processing apparatus 2 shown in FIG. 3, the exhaust gas processing apparatus 10B is provided with a post-processing unit 20 provided downstream of the second film processing unit 122 of the film processing unit 12. Prepare. Post-processing unit 20, an impurity such as toxic heavy metals during the second concentrated water W ₃₁ supplied through a concentrated water discharge line L ₃₁ from the second layer processing section 122 is removed, the post-processing water discharge line L ₇ The post-treatment water W ₇ from which impurities have been removed is discharged. As the post-processing unit 20, the same one as that shown in FIG. 12A described above can be used.

As described above, according to this embodiment, by providing the permeate W ₂₂ and evaporation unit 19 for evaporating the water concentrated water W _31, evaporated permeate W ₂₂ and moisture concentrate W ₃₁ Since it is possible to obtain steam, the waste water discharged from the exhaust

gas treatment devices

9A and 9B to the outside of the exhaust

gas treatment devices

9A and 9B can be significantly reduced. Further, by providing the post-processing unit 20 to remove impurities such as toxic heavy metals permeate W ₂₂ and concentrate water W _31, impurities such as toxic heavy metals permeate W ₂₂ and concentrate water W ₃₁ is removed Since it can be discharged, the amount of waste water discharged from the exhaust

gas processing apparatuses

10A and 10B to the outside of the exhaust

gas processing apparatuses

10A and 10B can be significantly reduced.

In each embodiment described above, the reduction treatment and precipitation treatment of the desulfurization waste water W _11, it is also possible to remove selenium as an adverse heavy metals contained in the desulfurization effluent W _11. Examples of the reduction treatment include reduction treatments using various reducing agents such as hydrogen peroxide (H ₂ O ₂ ). Moreover, as a precipitation process, precipitation processes, such as iron coprecipitation, are mentioned, for example.

Moreover, in each embodiment mentioned above, in order to prevent concentration increase by concentration of oxidation inhibitors such as humic acid and tannic acid, air, oxygen (O ₂ ), chlorine (Cl ₂ ) or the like for desulfurization waste water W ₁₁ At least one oxidizing agent selected from the group consisting of hypochlorous acid (ClO ⁻ ), hypochlorous acid (ClO ₂ ⁻ ), ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ), May be Since the oxidation inhibitor can be decomposed by the addition of the oxidizing agent, the concentration increase of the oxidation inhibitor can be prevented.

1, 2, 3, 4, 5 A, 5 B, 6, 7, 8 A, 8 B, 8 C, 8 D, 8 E, 8 F, 9 A, 9 B, 10 A, 10 B Exhaust gas treating apparatus 11 flue gas desulfurization part 12 membrane processing part 12 a separation membrane 12-1 First film processing unit 12-2 Second film processing unit 12-3 Third film processing unit 12-4 Fourth film processing unit 12-5 Fifth film processing unit 12-6 Sixth film processing unit 12- 7 Seventh membrane processing unit 120 Pressure vessel 1201 Desulfurization drainage introduction pipe 1202 Desulfurization drainage discharge pipe 1203 Water collection pipe 1203a Partition wall 1203b Downstream side water collection pipe 1203c Upstream side water collection pipe 121 First membrane processing part 122 Second membrane processing part 13 Section 14 make-up water supply unit 15 pretreatment unit 151 coagulation sedimentation unit 151a sludge 152 sand filtration unit 153 filtration unit 153a filtration membrane 16 mercury removal unit 161 solid-liquid separation unit 162 mercury treatment unit 17 water Measurement unit 18 Control unit 19 Evaporation treatment unit 20 Post-treatment unit 21 Anode 22 Cathode 23 Cation exchange membrane 23A 1-monovalent permselective cation exchange membrane 24 Anion-exchange membrane 24A Monovalent permselective anion exchange membrane 25A, 25B , 25C, 25D dialysis membrane W ₁₁ , W ₁₂ , W ₁₃ , W ₁₆ desulfurization drainage W ₁₄ pretreated water W ₁₅ , W ₂₁ , W ₃₁ concentrated water W _{21 A} circulating concentrated water W ₂₂ , W _22-1 , W _{22- 2} , W ₃₂ permeated water W ₂₃ , W ₂₄ , W ₂₅ , W ₃₃ circulating water W ₂₆ bypass water W ₄ dilution water W ₅ makeup water W ₇ post-treatment water L ₁ desulfurization drainage supply line L ₂₁ concentrated water supply line L _{21 A} concentrated water circulation line _{_{_{L 22, L 22-1, L 22-2}}} , L 32 permeate discharge line L ₃₁ concentrated water discharge line L ₄₁ dilution water supply line L ₄₂ up water branch line L _43, _{L 44} permeate supply line L ₆₁ concentrated water circulation line L ₆₂ permeate circulation line L ₇ aftertreatment water discharge line V _1, _{V 2} flow control valve

Claims

A flue gas desulfurization unit that cleans the flue gas and discharges desulfurization wastewater containing sulfate ions;
It has a first separation membrane for membrane separation of the desulfurization waste water into a first permeated water in which sulfate ions are reduced and a first concentrated water in which sulfate ions are concentrated, and the first concentrated water is subjected to the exhaust gas desulfurization unit A first membrane processing unit for discharging the first permeated water while supplying the
An exhaust gas processing apparatus comprising:
The exhaust gas treatment device according to claim 1, wherein the first separation membrane has a permeability of chloride ions higher than a permeability of sulfate ions in the desulfurization waste water.
The exhaust gas processing apparatus according to claim 1, further comprising a dilution water supply unit configured to supply dilution water for diluting the desulfurization waste water.
The dilution water supply unit is a makeup water supply unit that supplies makeup water to the flue gas desulfurization unit, and the makeup water supply unit supplies at least one part of the makeup water to the desulfurization drainage as the dilution water. The exhaust gas processing device according to claim 3.
The pre-processing part which removes the scale component in the said desulfurization waste water, and which supplies said desulfurization waste water which pre-processed to said 1st film process part is provided. The exhaust gas processing apparatus as described in a term.
The first membrane processing unit is capable of circulating at least one of the first permeated water and the first concentrated water to the desulfurization wastewater supplied to the first membrane processing unit,
When the chloride ion concentration of the first concentrated water exceeds a reference value, the flow rate of at least one of the first permeated water and the first concentrated water to be circulated to the desulfurization drainage is controlled to control the first concentration The exhaust gas processing apparatus according to any one of claims 1 to 5, further comprising a flow rate control unit that sets a chloride ion concentration in water to the reference value or less.
The first membrane processing unit is capable of circulating at least one of the first permeated water and the first concentrated water to the desulfurization wastewater supplied to the first membrane processing unit,
When the chloride ion concentration of the first permeated water is lower than a reference value, the flow rate of at least one of the first permeated water and the first concentrated water to be circulated to the desulfurization effluent is controlled to control the first permeated water. The exhaust gas processing apparatus according to any one of claims 1 to 6, further comprising a flow rate control unit that sets a chloride ion concentration in the permeated water to a reference value or more.
The first membrane processing unit is capable of circulating at least one of the first permeated water and the first concentrated water to the desulfurization wastewater supplied to the first membrane processing unit,
When the chloride ion concentration of the desulfurization waste water exceeds a reference value, the flow rate of at least one of the first permeated water and the first concentrated water circulating to the desulfurization waste water is controlled to form chloride in the desulfurization waste water The exhaust gas processing apparatus according to any one of claims 1 to 7, further comprising a flow rate control unit that makes the concentration of the target ions equal to or lower than a reference value.
A second membrane having a second separation membrane that performs membrane separation of the first permeated water containing chloride ion into a second permeated water with reduced chloride ion and a second concentrated water with concentrated chloride ion The exhaust gas processing apparatus according to any one of claims 1 to 8, further comprising a processing unit.
The exhaust gas treatment apparatus according to claim 9, wherein the second membrane processing unit supplies at least a part of the second permeate to the desulfurization drainage as dilution water.
The exhaust gas processing device according to claim 9, further comprising an evaporation processing unit configured to evaporate the second concentrated water to obtain evaporated water.
The exhaust gas processing apparatus according to any one of claims 9 to 11, further comprising: a post-processing unit that removes post-processing water by removing one of the impurities in the second concentrated water.
The exhaust gas processing device according to any one of claims 1 to 12, further comprising an evaporation processing unit configured to evaporate the first permeated water to obtain evaporated water.
The exhaust gas processing apparatus according to any one of claims 1 to 13, further comprising a post-treatment unit that removes post-treatment water by removing impurities in the first permeated water.
The exhaust gas processing device according to any one of claims 1 to 14, further comprising a solid-liquid separation unit configured to separate solid mercury and liquid mercury in the desulfurization waste water from the desulfurization waste water.
The exhaust gas treatment apparatus according to any one of claims 1 to 15, further comprising a mercury treatment unit that removes soluble mercury in the desulfurization effluent.
A flue gas desulfurization step of washing flue gas with a flue gas desulfurization section to discharge desulfurization waste water containing sulfate ions;
The desulfurization wastewater is membrane-separated by a first separation membrane into a first permeated water in which sulfate ions are reduced and a first concentrated water in which sulfate ions are concentrated, and the first concentrated water is supplied to the flue gas desulfurization unit A first membrane treatment step of discharging the first permeated water,
A method of treating exhaust gas comprising: