JP5910130B2 - Exhaust gas treatment apparatus and exhaust gas treatment method - Google Patents

Description

  The present invention relates to an exhaust gas treatment apparatus and an exhaust gas treatment method for removing NOx contained in exhaust gas.

  Combustion exhaust gas (exhaust gas) is generated when fossil fuel is burned in an engine such as a ship or a vehicle. The exhaust gas generated as a result of burning such a fossil fuel contains nitrogen oxides (hereinafter simply referred to as NOx). Since NOx is an air pollutant, emission concentration and emission amount are regulated by international organizations, countries, and local governments. Therefore, when the concentration of NOx contained in the exhaust gas discharged from the engine is equal to or higher than a predetermined regulation value, it is necessary to remove NOx from the exhaust gas using an exhaust gas treatment device for removing NOx.

  As an exhaust gas treatment apparatus that removes NOx, there is a selective catalytic reduction denitration apparatus that includes a denitration catalyst that promotes NOx reduction and a reducing agent that reduces NOx. However, if the denitration catalyst is not at a certain high temperature (for example, about 270 ° C.), the NOx reduction efficiency is lowered. Further, since urea water is generally used as a reducing agent, the cost for urea water is increased, and the disposal of excess urea water is costly.

  Therefore, for example, the exhaust gas is absorbed in seawater, and the seawater is accommodated in an anode tank and a cathode tank separated by a permeable membrane, respectively, and electrolysis is performed, so that NOx is used using a solution generated in the anode tank. Has been disclosed (for example, Patent Document 1).

Japanese Patent No. 3829184

However, in the technique of Patent Document 1, chloride ions (Cl ⁻ ) contained in seawater become chlorine (Cl ₂ ) gas by electrolysis, and chlorine gas is mixed into the exhaust gas after NOx is removed. Since chlorine gas is an air pollutant, regulations on emission concentrations and emissions are regulated by international organizations, national and local governments. Accordingly, it is necessary to separately provide a device for reducing the Cl ₂ gas in the exhaust gas after the NOx is removed to a regulation value or less, resulting in an increase in cost.

Therefore, in view of such problems, the present invention uses chlorine gas generated by electrolysis for removal of NOx, thereby efficiently removing NOx from the exhaust gas and significantly reducing the concentration of Cl ₂ gas in the exhaust gas. It is an object of the present invention to provide an exhaust gas treatment apparatus and an exhaust gas treatment method that can be used.

In order to solve the above-described problems, an exhaust gas treatment apparatus of the present invention includes an anode tank in which seawater is accommodated and an anode is provided, and a cathode tank in which seawater is accommodated and a cathode is provided, which are partitioned by an ion exchange membrane. Including one or more gases selected from the group consisting of NOx, NOx and SOx, and NOx and CO _2. After the reaction, the first exhaust gas treatment unit for cleaning the exhaust gas to be washed with seawater, the exhaust gas washed in the first exhaust gas treatment unit, and the Cl ₂ gas generated in the anode tank by electrolysis are brought into contact with each other. A second exhaust gas treatment section for producing a gas and washing the post-reaction gas with an anode solution produced in an anode tank by performing electrolysis; And a dissolved part which is a solution generated in the dissolving part, and a dissolving part for contacting the post-reaction gas washed by the second exhaust gas treatment part with the cathode precipitation solution containing the precipitate generated in the cathode tank. And a return part for returning to the exhaust gas treatment part.

  The dissolution unit may bubble the gas that has passed through the second exhaust gas treatment unit into the cathode precipitation solution.

  The first exhaust gas treatment unit may be a spray tower that sprays seawater on the exhaust gas, and the second exhaust gas treatment unit may be a spray tower that sprays at least one of the anode solution and the dissolved solution on the reacted gas. .

And Cl ₂ gas and the anode solution produced at the anode chamber by electrolysis is performed by gas-liquid separation, an anode separator unit for separating the Cl ₂ gas and the anode solution, the second exhaust gas treatment unit, The gas cleaned in the first exhaust gas treatment unit and the Cl ₂ gas separated in the anode separation unit are brought into contact with each other to generate a post-reaction gas, and the post-reaction gas is washed with the anode solution separated in the anode separation unit It is good.

  The voltage application unit may apply a voltage of 3.5V to 20V to the anode and the cathode.

  The pH of the anode solution may be pH 1 to pH 6, and the pH of the cathode solution produced in the cathode cell may be pH 8 to pH 14.

The precipitate generated in the cathode cell may include one or both of Mg (OH) ₂ and Ca (OH) ₂ .

In order to solve the above problems, an exhaust gas treatment method according to the present invention includes an anode tank in which seawater is contained and an anode is provided, and a cathode tank in which seawater is contained and a cathode is provided, which are partitioned by an ion exchange membrane. From an NOx, NOx and SOx, and NOx and CO ₂ group using an exhaust gas treatment device comprising an electrolytic cell and a voltage application unit that performs electrolysis by applying a voltage to an anode and a cathode An exhaust gas treatment method for treating an exhaust gas containing one or more selected gases, wherein the exhaust gas is washed with seawater, the washed exhaust gas, and Cl generated in the anode tank by electrolysis generating a ₂ gas and the contact is allowed to react after the gas, the reaction gas after the anode solution produced at the anode chamber by electrolysis is carried out The step of washing, the step of bringing the washed post-reaction gas into contact with the cathode precipitation solution containing the precipitate generated in the cathode chamber by electrolysis, and the step of contacting the washed post-reaction gas with the cathode precipitation solution And a step of cleaning the gas after the reaction with a dissolved solution, which is a solution generated in the step of causing the reaction.

According to the present invention, by using Cl ₂ gas generated by electrolysis for removal of NOx, it is possible to efficiently remove NOx from exhaust gas and to significantly reduce the concentration of Cl ₂ gas in the exhaust gas. Become.

It is explanatory drawing for demonstrating the specific structure of an exhaust gas processing apparatus. It is a flowchart for demonstrating the flow of a process of the exhaust gas processing method using an exhaust gas processing apparatus.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  When fossil fuel is burned in an engine such as a ship or a vehicle, exhaust gas is generated. The exhaust gas generated as a result of burning such a fossil fuel contains NOx. Since NOx is an air pollutant, it is necessary to remove NOx when the concentration of NOx contained in the exhaust gas discharged from the engine is equal to or higher than a predetermined regulation value. Hereinafter, the exhaust gas treatment apparatus 100 capable of efficiently removing NOx from the exhaust gas will be described.

(Exhaust gas treatment device 100)
FIG. 1 is an explanatory diagram for explaining a specific configuration of an exhaust gas treatment apparatus 100 according to the present embodiment. As shown in FIG. 1, the exhaust gas treatment device 100 includes an electrolytic cell 110, a voltage application unit 120, an anode separation unit 130, a cathode separation unit 140, a first exhaust gas treatment unit 150, and a second exhaust gas treatment unit 160. And a melting unit 170 and a return unit 180. In FIG. 1, the flow of gas (gas) is indicated by broken-line arrows, and the flow of liquid is indicated by solid-line arrows.

  The electrolytic cell 110 includes an anode cell 112 and a cathode cell 114, and the anode cell 112 and the cathode cell 114 are partitioned by an ion exchange membrane 116.

  Seawater is introduced into the anode tank 112 from a seawater source (not shown) through a pump 118a, a valve 118b, and a seawater introduction pipe 118c. The anode tank 112 is provided with seawater and an anode 112a. The anode 112a is made of a conductive material that can be generally used as an electrode, such as titanium (Ti) coated with platinum (Pt).

  Seawater is introduced into the cathode tank 114 from a seawater source (not shown) through a pump 118d, a valve 118e, and a seawater introduction pipe 118f. Moreover, the cathode tank 114 is provided with seawater and a cathode 114a. The cathode 114a is made of copper (Cu), nickel (Ni), iron (Fe), titanium (Ti), tungsten (W), molybdenum (Mo), chromium (Cr), platinum (Pt), aluminum (Al), zinc It is composed of a material using one or more metals such as (Zn) and cadmium (Cd), or an alloy such as brass or high-strength brass.

The voltage application unit 120 includes a hydrogen gas fuel cell or a device that generates power using hydrogen (H ₂ ) as a power source, such as a hydrogen diesel generator, an anode 112 a provided in the anode tank 112, and a cathode tank Seawater is electrolyzed by applying a voltage to the cathode 114 a provided at 114.

Here, _{H 2} supplied to the voltage application unit 120 includes a _{H 2} produced at the cathode chamber 114. Thus, the voltage application unit 120, and H ₂ by configuring an apparatus for generating power as a power source, it is possible to effectively utilize the H ₂ produced at the cathode chamber 114.

  The voltage applied by the voltage application unit 120 to the anode 112a and the cathode 114a is 3.5V to 20V, preferably 3.5V to 15V, more preferably 3.5V to 10V. By setting the voltage applied by the voltage application unit 120 to the anode 112a and the cathode 114a as described above, the pH of the anode solution AS2 described later can be easily adjusted to a desired value.

…反応式（３）

…反応式（４） When the voltage application unit 120 applies voltage to the anode 112a and the cathode 114a to perform electrolysis, the reactions shown in the following reaction formulas (1), (2), and (3) occur in the anode tank 112.
2Cl ⁻ → Cl ₂ + 2e ⁻
... Reaction formula (1)
2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻
... Reaction formula (2)

... Reaction formula (3)

... Reaction formula (4)

On the other hand, in the cathode cell 114, reactions shown in the following reaction formulas (5) to (9) occur.
2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻
... Reaction formula (5)
Mg ²⁺ + 2OH ⁻ → Mg (OH) ₂
... Reaction formula (6)
Ca ²⁺ + 2OH ⁻ → Ca (OH) ₂
... Reaction formula (7)
Mg ²⁺ + CO ₂ + H ₂ O → MgCO ₃ + 2H ⁺
... Reaction formula (8)
Ca ²⁺ + CO ₂ + H ₂ O → CaCO ₃ + 2H ⁺
... Reaction formula (9)

Then, in the anode tank 112, chlorine (Cl ₂ ), oxygen (O ₂ ), hypochlorous acid (HClO), and hypochlorite ion (ClO ⁻ ) are generated (reaction formulas (1) and (2)). , (3), (4)), H ₂ , magnesium hydroxide (Mg (OH) ₂ ), calcium hydroxide (Ca (OH) ₂ ), magnesium carbonate (MgCO ₃ ), and calcium carbonate in the cathode chamber 114. (CaCO ₃ ) is produced (see reaction formulas (5) to (9)).

  Thus, as the electrolysis progresses, the pH of the anode solution generated in the anode tank 112 is inclined to acidic (see reaction formulas (2), (3), and (4)) and is generated in the cathode tank 114. The pH of the cathode solution tends to be alkaline (see reaction formula (5)).

The anode solution AS1 containing Cl ₂ , O ₂ , HClO, and ClO ⁻ generated in the anode tank 112 is transferred from the anode tank 112 to the anode separator 130 through the valve 210a, the pump 210b, and the AS1 flow pipe 210c. be introduced.

On the other hand, the cathode solution CS1 containing H ₂ produced in the cathode tank 114 is introduced from the cathode tank 114 to the cathode separator 140 through the valve 210d, the pump 210e, and the CS1 flow pipe 210f. Further, Mg (OH) ₂ , Ca (OH) ₂ , MgCO ₃ , and CaCO ₃ produced in the cathode cell 114 are precipitated as solids (or gels), and Mg (OH) ₂ , Ca (OH) ) ₂ , MgCO ₃ , and CaCO ₃ in the form of a slurry cathode solution (hereinafter simply referred to as “cathode precipitation solution PS”) is dissolved in a dissolution unit 170 described later through a valve 210 g, a pump 210 h, and a PS flow pipe 210 i. It is introduced into the tank 172.

The anode separator 130 separates the anode solution AS1 into Cl ₂ gas and O ₂ gas and the anode solution AS2 by gas-liquid separation. The Cl ₂ gas and O ₂ gas separated in the anode separation unit 130 are retained in the gas retention space 130a, and then air is introduced from an air source (not shown) through a pump 212a, a valve 212b, and an air introduction pipe 212c. Extruded and guided through a gas pipe 214a and a valve 214b to a gas supply port 162a of a second exhaust gas processing unit 160 described later. Further, the anode solution AS2 separated in the anode separation unit 130 is introduced into the spray unit 164 of the second exhaust gas treatment unit 160 described later through the valve 216a, the pump 180c, and the AS2 flow pipe 216b.

The cathode separation unit 140 separates the cathode solution CS1 into H ₂ gas and cathode solution CS2 by gas-liquid separation. The H ₂ separated in the cathode separation unit 140 stays in the gas retention space 140a, and is then pushed out from the air source (not shown) by the air introduced through the pump 218a, the valve 218b, and the air introduction pipe 218c, and the gas pipe 218d. The voltage application unit 120 is introduced through the valve 218e. In addition, the cathode solution CS2 separated in the cathode separation unit 140 is discharged to the outside through the valve 218f.

The first exhaust gas treatment unit 150 is, for example, a spray tower, into which exhaust gas containing one or more gases selected from the group of NOx (nitrogen oxide), SOx (sulfur oxide), and CO ₂ is introduced. In addition, the exhaust gas is washed with seawater.

By configuring the first exhaust gas treatment unit 150 with a spray tower, it is possible to increase the superficial velocity (the flow rate of gas when it is assumed that there is no packing inside the tower) as compared with the bubble tower and the packed tower. can, NOx, SOx, and the horizontal inner diameter to achieve the same removal rate of one or more of the gas of CO ₂ can be made smaller. Therefore, the occupied volume of the first exhaust gas treatment unit 150 can be reduced, and the exhaust gas treatment apparatus 100 can be mounted even in a place where the occupied volume of a ship or the like is limited.

Specifically, the first exhaust gas treatment unit 150 includes a main body 152, an exhaust gas introduction unit 154, and a spray unit 156. The exhaust gas introduction unit 154 includes a valve 154a and an exhaust gas introduction pipe 154b, and introduces the exhaust gas X1 containing NOx, SOx, and CO ₂ into the main body 152.

  The spray unit 156 communicates with a seawater source (not shown) through a pump 158a, a valve 158b, and a seawater introduction pipe 158c, and sprays seawater on the exhaust gas X1 introduced by the exhaust gas introduction unit 154.

In this way, in the first exhaust gas treatment unit 150, the exhaust gas X1 is sprayed and washed with seawater, so that SOx and CO ₂ contained in the exhaust gas X1 are absorbed (dissolved) in the seawater. Thus, the first exhaust gas treatment unit 150 removes SOx, CO ₂ , oil mist, and dust from the exhaust gas X1.

The exhaust gas from which the SOx, CO ₂ , oil mist, and dust are removed from the exhaust gas X1 (hereinafter simply referred to as exhaust gas X2) is exhausted from the second exhaust gas processing unit 160 described later through the gas pipe 220a and the valve 220b. It is guided to the inlet 162b. The seawater that has absorbed SOx and CO ₂ is discharged to the outside through the valve 220c.

The second exhaust gas treatment unit 160 is, for example, a spray tower, and generates a post-reaction gas by bringing the exhaust gas X2 into contact with the Cl ₂ gas supplied from the anode separation unit 130. Then, the second exhaust gas treatment unit 160 cleans the reacted gas with the anode solution AS2 supplied from the anode separation unit 130.

  By configuring the second exhaust gas treatment unit 160 with a spray tower, the superficial velocity can be increased as compared with a bubble tower or a packed tower, and the inner diameter in the horizontal direction for achieving the same removal rate as NOx. Can be reduced. Therefore, the occupied volume of the second exhaust gas treatment unit 160 can be reduced, and the exhaust gas treatment device 100 can be mounted even in a place where the occupied volume of a ship or the like is limited.

  Specifically, the second exhaust gas processing unit 160 includes a main body 162 and a spray unit 164.

The main body 162 is provided with a gas supply port 162a and an exhaust gas introduction port 162b. The gas supply port 162a communicates with the gas retention space 130a of the anode separation unit 130 through the gas pipe 214a and the valve 214b, and the Cl ₂ gas and the O ₂ gas separated by the anode separation unit 130 are gas supply ports 162a. Through the main body 162.

  The exhaust gas introduction port 162b communicates with the gas retention space 150a of the first exhaust gas treatment unit 150 through the gas pipe 220a and the valve 220b, and the exhaust gas X2 generated in the first exhaust gas treatment unit 150 passes through the exhaust gas introduction port 162b. It is supplied into the main body 162.

The spray unit 164 communicates with the anode separation unit 130 through the valve 216a, the pump 180c, and the anode solution circulation pipe 216b, and Cl ₂ gas, O ₂ gas supplied from the gas supply port 162a, and the exhaust gas introduction port 162b. The anode solution AS2 is sprayed on the exhaust gas X2 introduced from above.

Then, in the main body 162, as shown in the following reaction formula (10), first, NOx in the exhaust gas X2 (here, NO is taken as an example) and Cl ₂ gas react to react with nitrosyl chloride (NOCl). Is generated.
2NO (g) + Cl ₂ (g) → 2NOCl (g)
... Reaction formula (10)
In the reaction formula, (g) represents gas.

  Then, when the anode solution AS2 is sprayed on NOCl by the spray unit 164, NOCl is absorbed (dissolved) in the anode solution AS2.

  Here, the pH of the anode solution AS2 is pH1 to pH6, preferably pH2 to pH5, more preferably pH2 to pH4. Thus, when the pH of the anode solution AS2 is low, that is, when the anode solution AS2 is acidic, NOCl can be efficiently absorbed.

  In order to change the pH of the anode solution AS2 from pH 1 to pH 6, the voltage applied to the anode 112a and the cathode 114a by the voltage applying unit 120 described above may be set to 3.5V to 20V.

Thus, in the second exhaust gas treatment unit 160, NOx is removed from the exhaust gas X2, and CO ₂ , surplus Cl ₂ gas and O ₂ gas (hereinafter simply referred to as “exhaust Cl ₂ gas” which cannot be removed in the first exhaust gas treatment unit 150). The surplus gas X3) is guided to a bubbling portion 174 of the dissolving portion 170 described later through a valve 222a and a surplus gas circulation pipe 222b. The anode solution AS3 that has absorbed NOx is discharged to the outside through the valve 222c.

The dissolving unit 170 includes an excess gas X3 containing excess Cl ₂ that is generated when the amount of Cl ₂ gas supplied to the second exhaust gas treatment unit 160 is larger than the amount necessary to decompose NOx in the exhaust gas X2. Is contacted with an alkaline cathodic precipitation solution PS. More specifically, the melting part 170 includes a melting tank 172 and a bubbling part 174.

  The dissolution tank 172 communicates with the cathode tank 114 through the valve 210g, the pump 210h, and the PS communication pipe 210i, and stores the cathode precipitation solution PS supplied from the cathode tank 114.

  The bubbling unit 174 communicates with the gas retention space 160a of the second exhaust gas treatment unit 160 through the valve 222a and the surplus gas circulation pipe 222b, and the surplus gas X3 supplied from the second exhaust gas treatment unit 160 is supplied to the cathode precipitation solution PS. Bubbling to

Then, the Cl ₂ gas contained in the surplus gas X3 is dissolved in the cathode precipitation solution PS in the dissolution tank 172. That is, the Cl ₂ gas can be removed from the surplus gas X3. The purified gas X4 from which Cl ₂ has been removed from the surplus gas X3 is discharged to the outside through the valve 176.

Further, as described above, the voltage application unit 120 applies a voltage of 3.5V to 20V to the anode 112a and the cathode 114a in order to change the pH of the anode solution AS2 from pH1 to pH6. Then, the pH of the cathode solution CS1 is changed from pH 8 to pH 14, and the reactions shown in the above reaction formulas (6) to (9) occur, and Mg (OH) ₂ , Ca (OH) ₂ , MgCO ₃ , and A cathode precipitation solution PS containing CaCO ₃ precipitates is produced.

…反応式（１１）
Ｈ_２Ｏ＋ＣＯ_２→ＨＣＯ_３ ⁻＋Ｈ^＋
…反応式（１２） Therefore, when the bubbling unit 174 bubbling the surplus gas X3 into the cathode precipitation solution PS, the reactions shown in the following reaction formulas (11) and (12) proceed in the dissolution tank 172, and the pH of the cathode precipitation solution PS is reduced. The pH decreases from pH 8 to less than pH 8, that is, the cathodic precipitation solution PS becomes acidic.

... Reaction formula (11)
H ₂ O + CO ₂ → HCO ₃ ⁻ + H ⁺
... Reaction formula (12)

When the cathode precipitation solution PS becomes acidic, reactions shown in the following reaction formulas (13) to (16) occur.
Mg (OH) ₂ + 2H ⁺ → Mg ²⁺ + 2H ₂ O
... Reaction formula (13)
Ca (OH) ₂ + 2H ⁺ → Ca ²⁺ + 2H ₂ O
... Reaction formula (14)
MgCO ₃ + 2H ⁺ → Mg ²⁺ + H ₂ O + CO ₂
... Reaction formula (15)
CaCO ₃ + 2H ⁺ → Ca ²⁺ + H ₂ O + CO ₂
... Reaction formula (16)

  The reaction shown in the reaction formula (13) is less than pH 9.2, the reaction shown in the reaction formula (14) is less than pH 12, the reaction shown in the reaction formula (15) is less than pH 10, and the reaction formula (16) The reaction shown proceeds at a pH below 8.

In this way, Mg (OH) ₂ , Ca (OH) ₂ , MgCO ₃ , and CaCO ₃ in the cathode precipitation solution PS are dissolved in the dissolving portion 170, and a dissolved solution SS is generated.

  The return unit 180 includes a valve 180a, a return pipe 180b, and a pump 180c, and returns the dissolved solution SS to the second exhaust gas processing unit 160. More specifically, the return pipe 180b is connected to the anode solution circulation pipe 216b, and the valve 180a is opened to drive the pump 180c, whereby the dissolved solution SS is sprayed to the spray section 164 of the second exhaust gas treatment section 160. To supply.

  As described above, since the solution SS is acidic, NOCl can be efficiently absorbed. Therefore, the return unit 180 returns the dissolved solution SS to the second exhaust gas treatment unit 160, so that not only the anode solution AS2 but also the dissolved solution SS can absorb NOCl.

In addition, Mg (OH) ₂ , Ca (OH) ₂ , MgCO ₃ , and CaCO ₃ that have conventionally been separated and discarded can be reused as the dissolution solution SS, thereby reducing the cost of disposal. Is possible.

As described above, according to the exhaust gas treatment apparatus 100 of the present embodiment, the NO 2 contained in the exhaust gas X2 can be converted to NOCl and removed by the Cl ₂ gas generated in the anode tank 112 by electrolysis. it can.

Further, the dissolution unit 170 dissolves the Cl ₂ gas contained in the surplus gas X3 in the cathode precipitation solution PS, so that the Cl ₂ gas can be removed from the surplus gas X3, and the Cl ₂ gas is released to the outside. It becomes possible to suppress.

  Furthermore, the dissolution unit 170 dissolves the excess gas X3 in the cathode precipitation solution PS, so that the alkaline cathode precipitation solution PS can be made acidic. Since the cathode precipitation solution PS (dissolution solution SS) that has become acidic can efficiently absorb NOCl, the return unit 180 replaces the anode solution AS2 with the anode solution AS2 or uses the solution SS with the anode solution AS2 as the second exhaust gas treatment unit. By returning to 160 spraying part 164, it becomes possible to absorb NOCl in the 2nd exhaust gas treating part 160 efficiently. Therefore, since the dissolved solution SS can be used together with the anode solution AS2 for absorption of NOCl, the amount of the anode solution AS2 necessary for absorbing the same amount of NOCl (NOx) can be reduced. it can. That is, it is possible to reduce the electric power used for the electrolysis for generating the anode solution AS2.

(Exhaust gas treatment method)
FIG. 2 is a flowchart for explaining the processing flow of the exhaust gas processing method using the exhaust gas processing apparatus 100 according to the present embodiment.

  First, in a state where seawater is stored in the anode tank 112 and the cathode tank 114, the voltage application unit 120 applies voltage to the anode 112a and the cathode 114a to perform electrolysis (S300). Then, the anode solution AS1 generated in the anode tank 112 is introduced into the anode separator 130, the cathode solution CS1 generated in the cathode tank 114 is introduced into the cathode separator 140, and the cathode precipitation solution generated in the cathode tank 114. PS is introduced into the dissolution tank 172 (S302).

The anode separator 130 separates the anode solution AS1 into Cl ₂ gas and anode solution AS2 by gas-liquid separation (S304). Further, the cathode separation unit 140 separates the cathode solution CS1 into H ₂ gas and cathode solution CS2 by gas-liquid separation (S306).

The first exhaust gas treatment unit 150, by spraying sea water into the exhaust gas X1, SOx from the exhaust gas X1, CO _2, oil mist, to remove the dust, SOx from the exhaust gas X1, CO _2, oil mist, dust is removed The exhaust gas X2 is sent to the second exhaust gas processing unit 160 (S308).

The second exhaust gas treatment unit 160 contacts the exhaust gas X2 cleaned in the seawater cleaning step S308 with the Cl ₂ gas separated in the anode separation step S304, and then reacts with the gas (including NOCl and surplus Cl ₂ gas). Is generated (S310).

  Subsequently, the second exhaust gas treatment unit 160 sprays the anode solution AS2 separated in the anode separation step S304 to the post-reaction gas to remove NClO from the post-reaction gas, and the post-reaction gas from which NClO has been removed. (Surplus gas X3) is sent to the dissolving part 170 (S312).

The dissolution part 170 makes the surplus gas X3 contact the cathode precipitation solution PS introduced in the electrolytic solution introduction step S302, and removes Cl ₂ gas from the surplus gas X3 to generate the purified gas X4 and the dissolved solution SS. (S314).

  Then, the return unit 180 supplies the dissolved solution SS to the spray unit 164 of the second exhaust gas processing unit 160 instead of the anode solution AS2 or together with the anode solution AS2. Then, the second exhaust gas treatment unit 160 sprays the dissolved solution SS on the post-reaction gas and removes NClO from the post-reaction gas (S316).

As described above, according to the exhaust gas treatment method according to the present embodiment, the Cl ₂ gas generated by electrolysis is used for the removal of NOx, so that NOx can be efficiently removed from the exhaust gas and the Cl ₂ in the exhaust gas can be removed. The concentration of the _two gases can be significantly reduced.

(Example 1)
Two liters of artificial seawater was accommodated in each of the cathode tank 114 and the anode tank 112, and the voltage application unit 120 applied a voltage of 5 V to the anode 112a and the cathode 114a. Then, the Cl ₂ gas generated in the anode tank 112 was introduced into a spray tower (second exhaust gas treatment unit 160) capable of treating the exhaust gas X1 of about 0.3 m ³ / h.

As a result, generation of Cl ₂ gas was confirmed in the anode tank 112, and the concentration thereof was 0.5% to 4%. Further, the free chlorine concentration in the anode solution AS2 produced in the anode tank 112 was 0.1 mg / L to 50 mg / L.

Production of H ₂ and precipitation of Mg (OH) ₂ and Ca (OH) ₂ were confirmed in the cathode cell 114, and the dry weight of Mg (OH) ₂ and Ca (OH) ₂ was about 10 g.

When the Cl ₂ generated in the anode tank 112 and the anode solution AS2 were introduced into the second exhaust gas treatment unit 160, the NO removal rate in the second exhaust gas treatment unit 160 was 99%. The concentration of excess Cl ₂ gas after removal of NO in the second exhaust gas treatment unit 160 was 0.05% to 0.4%.

(Example 2)
0.01% to 0.05% Cl ₂ gas was bubbled into an alkaline solution having a pH of about 10 at 0.0375 m ³ / h. As a result, the free chlorine concentration in the solution after bubbling was changed from 20 mg / L to 200 mg / L, and the pH became pH 2 to pH 3.

As described above, since the reactions shown in the reaction formulas (13) to (16) occur at a pH of less than 8, when a low concentration Cl ₂ gas of 0.01% to 0.05% is bubbled into an alkaline solution having a pH of about 10 Even so, it was found that Mg (OH) ₂ , Ca (OH) ₂ , MgCO ₃ , and CaCO ₃ can be dissolved. Therefore, when 0.05% to 0.4% surplus Cl ₂ gas having a higher concentration is bubbled into the cathode precipitation solution PS having a pH of 8 to 14, Mg (OH) ₂ , Ca (OH) ₂ , MgCO ₃ , It is assumed that CaCO ₃ can be dissolved.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the above-described embodiment, the configuration in which the exhaust gas treatment apparatus 100 includes the anode separation unit 130 and the cathode separation unit 140 has been described. However, gas-liquid separation can be performed in the anode tank 112 and the cathode tank 114, and the anode separator 130 and the cathode separator 140 can be omitted.

In the above-described embodiment, air is introduced to push out the Cl ₂ gas separated by the anode separation unit 130. However, the exhaust gas introduction unit 154 is branched to introduce the exhaust gas X1 instead of air. Also good.

  In the above-described embodiment, the cathode precipitation solution PS is not periodically discharged from the cathode tank 114, but the liquid containing the precipitate separated by the cathode separation unit 140 is not discharged to the outside, and all the solution is supplied to the dissolution unit 170. The dissolved solution SS may be produced by bubbling the exhaust gas X3 and introduced into the second exhaust gas processing unit 160.

In the above-described embodiment, the example in which the H ₂ generated in the cathode chamber 114 is introduced into the voltage application unit 120 through the gas pipe 218d and the valve 218e has been described. However, the present invention is not limited to this, and H ₂ generated in the cathode chamber 114 can be once collected in a gas holder and purified, and then introduced into the voltage application unit 120.

Furthermore, in the above-described embodiment, the voltage application unit 120 configured by an apparatus that generates power using hydrogen (H ₂ ) as a power source has been described as an example. However, the voltage application unit 120 only needs to be able to apply a voltage to the anode 112a and the cathode 114a, and may be, for example, a device that applies a voltage using a commercial power source.

  In the above-described embodiment, the example in which the first exhaust gas processing unit 150 and the second exhaust gas processing unit 160 are configured by spray towers has been described. However, the present invention is not limited thereto, and the first exhaust gas processing unit 150 and the second exhaust gas processing unit 160 may be bubble towers or packed towers. Also good.

  Furthermore, a pump and a valve may be provided in addition to the positions shown in the exhaust gas treatment apparatus 100.

  In addition, the dissolved solution SS may be used not only for absorbing NOCl but also as a disinfectant for ship excrement and ballast water.

  The present invention can be used for an exhaust gas treatment apparatus and an exhaust gas treatment method for removing NOx contained in exhaust gas.

DESCRIPTION OF SYMBOLS 100 ... Exhaust gas treatment apparatus 110 ... Electrolytic cell 120 ... Voltage application part 130 ... Anode separation part 150 ... 1st exhaust gas treatment part 160 ... 2nd exhaust gas treatment part 170 ... Melting | dissolving part 174 ... Bubbling part 180 ... Return part

Claims (8)

An electrolytic cell in which seawater is contained and an anode tank provided with an anode; and a cathode tank in which seawater is contained and a cathode is provided;
A voltage application unit that performs electrolysis by applying a voltage to the anode and the cathode;
NOx, NOx and SOx, and a first exhaust gas treatment unit for washing exhaust gas containing one or more gases selected from the group of NOx and CO ₂ with seawater;
By bringing the exhaust gas washed in the first exhaust gas treatment section into contact with the Cl ₂ gas generated in the anode tank by performing electrolysis to generate a post-reaction gas and performing electrolysis A second exhaust gas treatment unit for washing the post-reaction gas with the anode solution generated in the anode tank;
A dissolution part for bringing the post-reaction gas washed by the second exhaust gas treatment part into contact with a cathode precipitation solution containing a precipitate produced in the cathode tank by electrolysis;
A return unit for returning the dissolved solution generated in the dissolving unit to the second exhaust gas treatment unit;
An exhaust gas treatment apparatus comprising:   2. The exhaust gas treatment apparatus according to claim 1, wherein the dissolution unit bubbles the gas that has passed through the second exhaust gas treatment unit into the cathode precipitation solution. The first exhaust gas treatment unit is a spray tower that sprays the seawater on the exhaust gas,
3. The exhaust gas treatment apparatus according to claim 1, wherein the second exhaust gas treatment unit is a spray tower that sprays at least one of the anode solution and the dissolved solution onto the post-reaction gas. And Cl ₂ gas and the anode solution produced by the anode chamber by electrolysis is performed by gas-liquid separation, an anode separator unit for separating said anode solution and the Cl ₂ gas,
The second exhaust gas treatment unit generates a post-reaction gas by bringing the gas cleaned in the first exhaust gas treatment unit into contact with the Cl ₂ gas separated in the anode separation unit, and the anode separation unit separates the gas. The exhaust gas treatment apparatus according to any one of claims 1 to 3, wherein the post-reaction gas is washed with the prepared anode solution.   The exhaust gas treatment apparatus according to any one of claims 1 to 4, wherein the voltage application unit applies a voltage of 3.5 V to 20 V to the anode and the cathode.   6. The exhaust gas according to claim 1, wherein the pH of the anode solution is pH 1 to pH 6 and the pH of the cathode solution generated in the cathode tank is pH 8 to pH 14. Processing equipment. The exhaust gas according to any one of claims 1 to 6, wherein the precipitate generated in the cathode tank contains one or both of Mg (OH) ₂ and Ca (OH) _2. Processing equipment. Voltage is applied to the anode and the cathode, an anode tank in which seawater is accommodated and an anode is provided, an electrolytic cell in which seawater is contained and a cathode tank in which a cathode is provided is partitioned by an ion exchange membrane An exhaust gas treatment device including a voltage application unit that performs electrolysis, and treating exhaust gas containing one or more gases selected from the group consisting of NOx, NOx and SOx, and NOx and CO ₂ An exhaust gas treatment method for
Washing the exhaust gas with seawater;
Contacting the cleaned exhaust gas with the Cl ₂ gas generated in the anode tank by electrolysis to generate a post-reaction gas;
Washing the post-reaction gas with an anodic solution produced in the anode bath by electrolysis;
Bringing the washed post-reaction gas into contact with a cathode precipitation solution containing a precipitate produced in the cathode chamber by electrolysis;
Washing the post-reaction gas with a dissolved solution that is a solution generated in the step of contacting the washed post-reaction gas with the cathode precipitation solution;
An exhaust gas treatment method comprising:

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