Gas treatment device and gas treatment method

Abstract

To provide a gas treatment device and a gas treatment method of treating gas containing hydrogen sulfide, by carrying out an electrode reaction using hydrogen sulfide as an electron donor, capable of easily lowering the concentration of hydrogen sulfide in the gas below a required value, without increasing the cost relating to continuation treatment.SOLUTION: There are provided, to solve the problem described above, a gas treatment device of treating gas containing hydrogen sulfide, comprising a first reaction unit and a second reaction unit each having a pair of electrodes, a first gas introduction unit introducing the gas containing hydrogen sulfide to an anode side of the first reaction unit, and a second gas introduction unit introducing the gas treated in the first reaction unit to an anode side of the second reaction unit, with the first reaction unit and the second reaction unit each performing power generation treatment and / or electrolysis treatment, and a gas treatment method using the device, whereby, the concentration of hydrogen sulfide in the gas can be extremely lowered at a low cost.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas treatment apparatus and a gas treatment method for treating a gas containing hydrogen sulfide.

Background Art

[0002] Conventionally, various gas treatments corresponding to the components in the gas have been widely performed on naturally occurring gases and gases generated in various treatment processes, in view of the effective utilization of the gas and the impact on the environment. In particular, for gases containing hydrogen sulfide, since hydrogen sulfide has strong corrosiveness and has a large impact on the environment and the like, it is common to perform a desulfurization treatment.

[0003] As the desulfurization treatment, those called dry desulfurization and wet desulfurization using physicochemical reactions are known. Dry desulfurization and wet desulfurization have high desulfurization performance, but are treatments that require desulfurizing agents such as iron agents and chemicals such as alkalis. There are problems such as high running costs due to the regular replacement of the desulfurizing agent and the use of a large amount of chemicals, and the cost of treating a large amount of waste generated after the treatment.

[0004] In recent years, as one of the desulfurization treatments, what is called biological desulfurization using microorganisms has attracted attention. Biological desulfurization is to bring a gas to be treated (a gas containing hydrogen sulfide) into contact with microorganisms through a packed bed carrying the microorganisms, and oxidize hydrogen sulfide in the gas. Therefore, the treatment by biological desulfurization is expected to be able to treat at a low running cost because the costs related to the use of desulfurizing agents, chemicals, etc. and the costs related to the treatment of waste generated after the treatment are less than those of dry desulfurization and wet desulfurization.

[0005] For example, Patent Document 1 describes a desulfurization apparatus for digester gas including a biological desulfurization tower having a packed bed layer to which microorganisms that oxidize and decompose hydrogen sulfide adhere, means for introducing digester gas into the tower, means for discharging treated gas from the tower, and means for supplying air or oxygen to the tower.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The desulfurization treatment using biological desulfurization as described in Patent Document 1 can be expected to be operated at low cost. However, the treatment using microorganisms is vulnerable to temperature changes. Once the treatment stops, it becomes difficult to control stable treatment conditions, and compared with dry desulfurization and wet desulfurization, the low treatment efficiency is a major problem.

[0008] Also, as described in Patent Document 1, the desulfurization treatment using biological desulfurization requires the supply of air or oxygen to be under aerobic conditions. For this reason, air or oxygen is mixed into the gas after the desulfurization treatment, which is a major problem when attempting to effectively utilize the gas after the desulfurization treatment.

[0009] Furthermore, when effectively utilizing the gas after the desulfurization treatment, it is required to reduce the hydrogen sulfide concentration in the gas to a concentration lower than a predetermined value (hereinafter also referred to as the "required value"). However, when using a plurality of treatment facilities (for example, a combination of biological desulfurization and dry desulfurization) to meet this required value, there is a problem that the initial cost and running cost of each treatment facility, and further maintenance according to each treatment facility are required, resulting in an increased load related to continuous treatment.

[0010] On the other hand, the present inventor has already studied a gas treatment apparatus and a gas treatment method capable of treating a gas containing hydrogen sulfide at low cost and efficiently by performing an electrode reaction using hydrogen sulfide as an electron donor. And also in the gas treatment by the electrode reaction using hydrogen sulfide as an electron donor, there is a need for a technique to surely reduce the hydrogen sulfide concentration in the gas to a concentration lower than the required value and to maintain the low-concentration state (continuous treatment) at low cost.

[0011] An object of the present invention is to provide a gas treatment apparatus and a gas treatment method for treating a gas containing hydrogen sulfide by performing an electrode reaction using hydrogen sulfide as an electron donor, which can easily reduce the hydrogen sulfide concentration in the gas to a concentration lower than a required value without increasing the cost associated with continuous treatment.

Means for Solving the Problems

[0012] As a result of intensive studies on the above problems, the present inventor has found that in the treatment of a gas containing hydrogen sulfide, by performing an electrode reaction using hydrogen sulfide as an electron donor a plurality of times, it is possible to efficiently reduce the hydrogen sulfide concentration without increasing the cost associated with continuous treatment, and thus completed the present invention. That is, the present invention is the following gas treatment apparatus and gas treatment method.

[0013] The gas treatment apparatus of the present invention for solving the above problems is a gas treatment apparatus for treating a gas containing hydrogen sulfide, comprising: a first reaction part having a pair of electrodes; a second reaction part having a pair of electrodes; a first gas introduction part for introducing a gas containing hydrogen sulfide to the anode side of the first reaction part; and a second gas introduction part for introducing the gas treated in the first reaction part to the anode side of the second reaction part, wherein the first reaction part and the second reaction part are characterized by performing power generation treatment and / or electrolysis treatment. The gas treatment apparatus of the present invention introduces a gas containing hydrogen sulfide to the anode side of a first reaction part having a pair of electrodes, and allows an electrode reaction using hydrogen sulfide contained in the gas as an electron donor to proceed, thereby enabling power generation treatment or electrolysis treatment using hydrogen sulfide. Further, the gas treated in the first reaction part is introduced to the anode side of the second reaction part, and by allowing the electrode reaction (power generation treatment or electrolysis treatment) using hydrogen sulfide as an electron donor to proceed again, it becomes possible to extremely reduce the hydrogen sulfide concentration in the gas. Also, thereby, treatment can be performed at a lower cost compared to general dry desulfurization or wet desulfurization, and control of stable treatment conditions becomes easier compared to biological desulfurization. Therefore, it is also possible to continuously perform low-cost and stable desulfurization treatment in the treatment of a gas containing hydrogen sulfide.

[0014] Further, as an embodiment of the gas treatment apparatus of the present invention, power generation treatment is performed in the first reaction part, and electrolysis treatment is performed in the second reaction part. According to this feature, in the first reaction part, since power generation treatment is performed using a gas with a high hydrogen sulfide concentration, the power generation efficiency is high, and electrical energy can be effectively recovered. Further, since the gas with a reduced hydrogen sulfide concentration in the first reaction part is subjected to electrolysis treatment in the second reaction part, it becomes possible to extremely reduce the hydrogen sulfide concentration. That is, according to this feature, it is possible to provide a gas treatment apparatus capable of extremely reducing the hydrogen sulfide concentration in the gas while increasing the recovery efficiency of electrical energy.

[0015] Further, as an embodiment of the gas treatment apparatus of the present invention, in at least one of the first reaction part and the second reaction part, electrolysis treatment is performed, and the electrolytic solution on the anode side after the electrolysis treatment is used as the electrolytic solution on the cathode side or in another reaction part. According to this feature, the electrolytic solution on the anode side after electrolysis treatment is from neutral to acidic, and can be neutralized by using it as the electrolytic solution on the cathode side. When discharging the electrolytic solution, it is possible to reduce the chemical cost related to neutralization. Further, after neutralizing the electrolytic solution on the anode side after electrolysis treatment with an alkaline agent, by using it as the electrolytic solution on the anode side of other reaction parts, the usage amount of the electrolytic solution itself can be reduced.

[0016] Further, as an embodiment of the gas treatment device of the present invention, based on the hydrogen sulfide concentration in at least one of the gas containing hydrogen sulfide, the gas treated in the first reaction part, and the gas treated in the second reaction part, it includes a control part that performs control related to the treatment of the first reaction part and / or the second reaction part, and the control in the control part includes switching between the power generation treatment and the electrolysis treatment in the first reaction part and / or the second reaction part, or voltage control related to the electrolysis treatment in the first reaction part and / or the second reaction part. According to this feature, corresponding to the change in the hydrogen sulfide concentration in the gas, it is possible to switch the electrolysis treatment and the power generation treatment in each reaction part, or control the voltage of the electrolysis treatment, etc., to appropriately select the content related to the treatment in each reaction part and improve the efficiency of the treatment. Therefore, it is possible to provide a gas treatment device that can further improve the recovery efficiency of electrical energy and more surely reduce the hydrogen sulfide concentration in the gas to a low concentration.

[0017] Further, as an embodiment of the gas treatment device of the present invention, power generation treatment is performed in at least one of the first reaction part and / or the second reaction part, and the electrical energy obtained by the power generation treatment is used as an energy source related to the operation of the device. According to this feature, since the electrical energy obtained by the power generation treatment becomes an energy source related to the operation of the gas treatment device, it is possible to provide a gas treatment device capable of energy saving. Further, it is possible to provide a gas treatment device capable of significantly reducing the running cost particularly in continuous treatment.

[0018] The gas treatment method of the present invention for solving the above problems is a gas treatment method for treating a gas containing hydrogen sulfide, comprising: a first gas introduction step of introducing a gas containing hydrogen sulfide to the anode side of a first reaction part having a pair of electrodes; a first reaction step of performing a power generation treatment or an electrolysis treatment in the first reaction part; a second gas introduction step of introducing the gas treated in the first reaction step to the anode side of a second reaction part having a pair of electrodes; and a second reaction step of performing a power generation treatment or an electrolysis treatment in the second reaction part. According to this gas treatment method, since the electrode reaction (power generation treatment or electrolysis treatment) using hydrogen sulfide as an electron donor is performed in multiple stages by the first reaction step and the second reaction step, it is possible to extremely reduce the hydrogen sulfide concentration in the gas. In addition, the treatment can be performed at a lower cost compared to general dry desulfurization and wet desulfurization, and the control of stable treatment conditions is easier compared to biological desulfurization. Therefore, it is also possible to perform a low-cost and stable desulfurization treatment in the treatment of a gas containing hydrogen sulfide.

[0019] Moreover, as an embodiment of the gas treatment method of the present invention, it further comprises a gas flow path switching step of switching the gas flow paths in the first gas introduction step and the second gas introduction step. After a predetermined time has elapsed, by the gas flow path switching step, the gas containing hydrogen sulfide is introduced into the second reaction part through the second gas introduction step, and the gas treated in the second reaction part is introduced into the first reaction part through the first gas introduction step. According to this feature, by appropriately switching the hydrogen sulfide concentration in the gas introduced into the first reaction part and the gas introduced into the second reaction part, it is possible to perform continuous treatment without causing the load on the electrodes in each reaction part to be biased to one side. Thereby, a decrease in the treatment efficiency in the gas treatment apparatus can be suppressed. Furthermore, the maintenance of the gas treatment apparatus becomes easy, and it is possible to reduce the running cost.

[0020] As another embodiment of the gas treatment method of the present invention, after a predetermined period of time, among the first reaction section and the second reaction section, the electrode in one of the reaction sections is replaced with a new electrode, and the used electrode after replacement is used as the electrode in the other reaction section. It is characterized by comprising an electrode replacement step. According to this feature, instead of replacing all the electrodes in each reaction section at once, it is possible to maintain and improve the electrode reaction efficiency with new electrodes and reduce the maintenance cost by using the used electrodes in the other reaction section. Thus, it is possible to provide a gas treatment method that enables both efficient reduction of hydrogen sulfide concentration and reduction of running cost.

Effect of the Invention

[0021] According to the present invention, in a gas treatment apparatus and a gas treatment method for treating a gas containing hydrogen sulfide by performing an electrode reaction using hydrogen sulfide as an electron donor, it is possible to provide a gas treatment apparatus and a gas treatment method that can easily reduce the hydrogen sulfide concentration in the gas to a concentration lower than the required value without increasing the cost related to continuous treatment.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0023] Hereinafter, embodiments of the gas treatment apparatus and the gas treatment method according to the present invention will be described in detail with reference to the drawings. A part of the description regarding the gas treatment method in the present invention shall be replaced with the description of the operation of the gas treatment apparatus in the present invention. Note that the gas treatment apparatus and the gas treatment method described in the embodiments are merely examples for explaining the gas treatment apparatus and the gas treatment method according to the present invention, and are not limited thereto.

[0024] In the gas treatment apparatus and the gas treatment method of the present invention, the gas to be treated is not particularly limited as long as it is a gas containing hydrogen sulfide. Specific examples include, for example, naturally occurring gases such as volcanic gases, gases generated in various processing processes such as oil refining and chemical product manufacturing, and gases generated in various treatment processes such as biogas generated by methane fermentation treatment. In particular, the gas to be treated in the gas treatment apparatus and gas treatment method of the present invention is preferably biogas generated by anaerobic digestion. Generally, biogas generated by anaerobic digestion contains hydrogen sulfide in addition to methane that can be effectively utilized as fuel, so a desulfurization treatment is required. And although details will be described later, in the gas treatment apparatus of the present invention, it is not necessary to supply air (oxygen) like biological desulfurization to the location (anode side of the reaction section) where the gas containing hydrogen sulfide is introduced and reacted. For this reason, it has the advantage that it is possible to recover and utilize the gas after desulfurization as high-purity methane gas without air (oxygen) being mixed in.

[0025] Moreover, specific examples of the gas generation source where the gas to be treated is generated include petroleum refining facilities, natural gas refining facilities, coke manufacturing facilities, hydrogen manufacturing facilities, tire manufacturing facilities, kraft pulp manufacturing facilities, solid battery manufacturing facilities, waste treatment facilities, wastewater / sewage treatment facilities, hot spring areas, and the like.

[0026] The gas treatment apparatus and gas treatment method in the present invention utilize an electrode reaction in which the gas to be treated (hydrogen sulfide) proceeds as an electron donor to generate electricity and perform desulfurization. Here, whether a certain substance functions as an electron donor is relatively determined by a combination with a substance that functions as an electron acceptor (hereinafter simply referred to as an "electron acceptor"). That is, in the present invention, a substance that is less likely to release electrons than hydrogen sulfide, that is, a substance having a higher redox potential than hydrogen sulfide, is used as the electron acceptor. For example, substances that function as electron acceptors in the present invention include, for example, oxygen, compounds / mixtures containing oxygen, and the like. Also, in the present invention, substances other than hydrogen sulfide that function as electron donors may be referred to as reducing substances. Examples of such reducing substances include hydrogen, ammonia, and the like.

[0027] 〔First Embodiment〕 FIG. 1 is a schematic explanatory diagram showing the structure of the gas treatment apparatus in the first embodiment of the present invention. As shown in Fig. 1, the gas treatment apparatus 1A in this embodiment includes a first reaction unit 2, a first gas introduction unit 3, a second reaction unit 4, and a second gas introduction unit 5. In addition, in the gas treatment apparatus 1A of this embodiment, the first reaction unit 2 and the second reaction unit 4 are respectively formed in independent casings (reaction tanks, electrochemical cells). The gas treatment apparatus 1A shown in Fig. 1 introduces, via the first gas introduction unit 3, a gas to be treated (gas G containing hydrogen sulfide, hereinafter also simply referred to as "gas G") from a gas generation source into the first reaction unit 2. Then, by causing an electrode reaction using hydrogen sulfide contained in gas G as an electron donor to proceed with the electrodes 23a and 23b disposed in the first reaction unit 2, power generation treatment or electrolysis treatment is performed. Further, the gas treated in the first reaction unit 2 (hereinafter referred to as "gas G1") is introduced into the second reaction unit 4 via the second gas introduction unit 5. Then, by causing an electrode reaction using hydrogen sulfide contained in gas G1 as an electron donor to proceed with the electrodes 43a and 43b disposed in the second reaction unit 4, power generation treatment or electrolysis treatment is performed, and the gas treated in the second reaction unit 4 (hereinafter referred to as "gas G2") is discharged out of the system. Hereinafter, details of each component of the gas treatment apparatus 1A will be described.

[0028] (First reaction unit) The first reaction unit 2 is for performing power generation treatment or electrolysis treatment by the reaction of hydrogen sulfide in gas G containing hydrogen sulfide. More specifically, the first reaction unit 2 is for causing an electrode reaction using hydrogen sulfide as an electron donor to proceed, and performing electric energy recovery or removal of sulfur components in the gas (desulfurization treatment). Hereinafter, the structure of the first reaction unit 2 of this embodiment will be described mainly from the viewpoint related to power generation treatment. Details of the reactions (treatment steps) related to the power generation treatment and electrolysis treatment by the first reaction unit 2 of this embodiment will be described later.

[0029] FIG. 2A and FIG. 2B are schematic explanatory diagrams showing a first reaction section and its peripheral structure of a gas treatment apparatus according to a first embodiment of the present invention. Note that FIG. 2A and FIG. 2B show different structures related to the first gas introduction section 3. Hereinafter, the drawing numbers in the description related to the structures common to FIG. 2A and FIG. 2B are denoted as "FIG. 2".

[0030] As shown in FIG. 2, the first reaction section 2 of the present embodiment includes, in a housing, a first cell 21a and a second cell 21b, an ion exchanger 25 provided so as to partition between the cells 21a and 21b, and a pair of electrodes 23a and 23b respectively disposed on the cells 21a and 21b. Here, the first gas G is introduced into the first cell 21a through a first gas introduction section 3 described later, and the hydrogen sulfide contained in the gas G is formed to react at the electrode 23a. The electrode 23a disposed on the first cell 21a functions as an anode. On the other hand, the second cell 21b is formed to store or supply an electron acceptor, and the electrode 23b disposed on the second cell 21b functions as a cathode. Further, the electrodes 23a and 23b are connected to an external circuit C1 by a conducting wire. Thereby, in the first reaction section 2, it is possible to recover and utilize (power generation process) the electrical energy generated by hydrogen sulfide acting as an electron donor and to perform desulfurization (electrolysis process) by applying a voltage.

[0031] The first cell 21a only needs to include the electrode 23a and be connected to the first gas introduction section 3, and be formed such that the hydrogen sulfide in the gas G reacts at the electrode 23a, and the material and shape are not particularly limited. Here, in the first reaction section 2, in order for the electrode reaction using hydrogen sulfide as an electron donor to proceed efficiently and stably, in the first cell 21a, it is preferable that the hydrogen sulfide in the gas G introduced through the first gas introduction section 3 is in a state dissolved in an aqueous solution. For this reason, as the first cell 21a, for example, as shown in FIG. 2, it can be a structure having a space capable of temporarily storing the gas G and the aqueous solution introduced from the introduction port 22a through the first gas introduction section 3.

[0032] In addition, the first cell 21a may be provided with a recovery port 22b and a pipe 26 for recovering the gas after the hydrogen sulfide has undergone an electrode reaction at the electrode 23a and discharging it outside the first cell 21a. Thereby, the gas G1 from which (a part of) the sulfur component has been removed from the gas G containing hydrogen sulfide can be efficiently recovered. At this time, the positional relationship between the inlet 22a and the recovery port 22b is not particularly limited. For example, as shown in FIG. 2, in addition to providing the inlet 22a on the side surface of the first cell 21a and the recovery port 22b on the upper surface of the first cell 21a, the inlet 22a may be provided on the side surface of the first cell 21a and the recovery port 22b may be provided on the bottom surface of the first cell 21a, or the inlet 22a and the recovery port 22b may be provided on the side surface of the first cell 21a, and the recovery port 22b may be provided at a position higher (or lower) in the vertical direction than the inlet 22a. In particular, when the gas G is biogas generated by anaerobic digestion, since the main component of the gas G1 is methane gas that does not dissolve in water and is lighter than air, as shown in FIG. 2, it is preferable to provide the recovery port 22b on the upper surface of the first cell 21a.

[0033] The means for storing the aqueous solution in the first cell 21a is not particularly limited. For example, the aqueous solution may be supplied into the first cell 21a in advance before the operation of the gas treatment device 1A, or the aqueous solution may be supplied through the first gas introduction part 3 described later. In addition, the properties (physical properties, contained components, etc.) of the aqueous solution stored in the first cell 21a are not particularly limited, but those that do not inhibit the electrode reaction are preferable, and those that promote the electrode reaction are more preferable. Specific examples of the aqueous solution in the present embodiment include, for example, pure water, tap water, river water, and electrolyte solutions. As described above, it is preferable from the viewpoint of reaction efficiency to store the aqueous solution in the first cell 21a and dissolve hydrogen sulfide, but it is not limited thereto. For example, the gas G may be introduced into the first cell 21a from the first gas introduction part 3, and the reaction of hydrogen sulfide may proceed in the first cell 21a in a gaseous state.

[0034] The first cell 21a may be provided with drainage means for discharging the stored aqueous solution and water supply means for supplying the aqueous solution. As will be described later, reaction products (such as sulfur and sulfuric acid) generated during the treatment process are present in the aqueous solution in the first cell 21a. For this reason, the aqueous solution discharged from the first cell 21a needs to be separately treated according to the generated reaction products. Therefore, from the viewpoint of reducing running costs, it is preferable to reduce the frequency of discharging the aqueous solution in the first cell 21a to the outside of the system.

[0035] The second cell 21b may be provided with an electrode 23b and may be formed so as to store or supply an electron acceptor for hydrogen sulfide, and the material and shape are not particularly limited.

[0036] Here, the form of the electron acceptor may be either a gas or a liquid. As the liquid, it may be a solution in which a solid agent is dissolved, or a solution in which a gas is mixed (dissolved). Regarding specific examples of the electron acceptor in the present embodiment, for example, as the gas, oxygen and gases containing oxygen can be mentioned. The gas containing oxygen includes those containing oxygen as a mixture such as air, and those containing oxygen as an element constituting a compound such as carbon dioxide. When a gas is used as the electron acceptor, there are advantages that the treatment of the discharged material after the reaction is unnecessary (or easy), and the cost related to obtaining can be reduced. In order to maximize these advantages, it is particularly preferable to use air as the electron acceptor. Further, as other examples of the electron acceptor in the present embodiment, for example, as the liquid, a solution containing dissolved oxygen, an aqueous solution of an oxidizing agent such as an aqueous solution of potassium ferricyanide, etc. can be mentioned. When a liquid is used as the electron acceptor, since it is easy to handle a compound (oxidizing agent) having a high effect as the electron acceptor, there is an advantage that the power generation efficiency can be further improved. From the viewpoint of improving the power generation efficiency, it is particularly preferable to use an aqueous solution of potassium ferricyanide as the electron acceptor.

[0037] As the second cell 21b, for example, as shown in FIG. 2, in the second cell 21b, in order to supply a gaseous electron acceptor (such as oxygen, air, etc.) to the electrode 23b, an electron acceptor supply port 24a for supplying gas and an electron acceptor discharge port 24b for discharging the gas after the reaction are provided. Further, as another example of the second cell 21b, a space capable of storing a liquid is provided in the second cell 21b, and as the electron acceptor supply port 24a and the electron acceptor discharge port 24b, those capable of supplying a solution of the electron acceptor and discharging the solution after the reaction are provided, respectively. Thereby, electrons from the electrode 23a can be received by the electron acceptor via the electrode 23b, and a current flows between the electrode 23a and the electrode 23b to generate electricity. Further, the electron acceptor after the reaction is quickly discharged to the outside of the first reaction part 2 via the electron acceptor discharge port 24b. Note that a flow rate adjusting mechanism such as a valve may be provided at the electron acceptor supply port 24a and / or the electron acceptor discharge port 24b so that the concentration of the electron acceptor in the second cell 21b can be adjusted. Further, a control mechanism for controlling the flow rate adjusting mechanism may be provided so that the electron acceptor concentration corresponding to the amount of electrons generated by the reaction at the electrode 23a is maintained. Thereby, it is possible to suppress a decrease in the reaction efficiency related to the electron transfer between the electrode 23a and the electrode 23b and to suppress a decrease in the power generation efficiency.

[0038] In FIG. 2, one electron acceptor supply port 24a and one electron acceptor discharge port 24b are shown, but the present invention is not limited thereto. For example, a plurality of electron acceptor supply ports 24a and electron acceptor discharge ports 24b may be provided. In particular, when a gas containing oxygen is used as the electron acceptor, as will be described later, water is generated by the reaction at the electrode 23b. Therefore, when a plurality of electron acceptor discharge ports 24b are provided, for example, those for discharging gas and those for discharging liquid may be provided separately.

[0039] The ion exchanger 25 may have any known configuration that allows ions to permeate, and is not particularly limited. In particular, a cation exchange membrane that can permeate hydrogen ions generated at the electrode 23a (anode side) can be mentioned. As a result, hydrogen ions move from the electrode 23a (anode side) to the electrode 23b (cathode side), so that the reaction efficiency of the electron acceptor at the electrode 23b can be increased, and the power generation efficiency can be improved. Further, it is more preferable that the ion exchanger 25 has low oxygen permeability. This suppresses the movement of the electron acceptor (oxygen) supplied to the electrode 23b (cathode side) to the electrode 23a side, and it becomes possible to suppress the reduction in the reaction efficiency of the electron donor at the electrode 23a due to oxygen. In addition, in FIG. 2, the ion exchanger 25 is shown as being provided separately from the electrodes 23a and 23b, but is not limited thereto. For example, integrating a material having ion exchange ability with the electrodes 23a and / or 23b can be mentioned. As a result, the entire first reaction unit 2 can be miniaturized, and the time required for maintenance work can be shortened.

[0040] The electrode 23a is an electrode that recovers electrons from hydrogen sulfide (reducing substance) and functions as a so-called anode. Further, the electrode 23a in the present embodiment is arranged so that the reaction of hydrogen sulfide proceeds in the first cell 21a. As shown in FIG. 2, when an aqueous solution is stored in the first cell 21a, the electrode 23a is arranged so as to be in contact with the aqueous solution.

[0041] The electrode 23a may be any electrode that functions as an anode, and is not particularly limited in terms of material and shape. The material and shape of the electrode 23a can be appropriately selected in consideration of material procurement, processing costs, the reaction efficiency of the reducing substance at the electrode 23a, and the like. Examples of the material of the electrode 23a include, for example, carbon and metals (titanium, stainless steel, platinum, copper, etc.) that are widely used as electrode materials in the field of electrochemistry. Examples of the shape of the electrode 23a include, for example, a flat plate shape, a rod shape, and a mesh shape.

[0042] The electrode 23a in this embodiment reacts using hydrogen sulfide as a direct electron donor. It is different from an electrode related to a so-called microbial fuel cell that contacts or supports microorganisms on the electrode surface and obtains electrical energy by utilizing the metabolic ability of the microorganisms. Therefore, the mass transfer of hydrogen sulfide to the surface of the electrode 23a is not inhibited by the microorganisms, the reaction efficiency as hydrogen sulfide (the mass transfer rate of hydrogen sulfide to the electrode 23a) can be improved, and the power generation efficiency can be improved. Also, the electrode 23a in this embodiment does not recover electrons generated by the metabolism of microorganisms, but directly recovers electrons from hydrogen sulfide (a reducing substance). Therefore, the metabolism of microorganisms does not become rate-limiting, the reaction efficiency as an electron donor (the electron recovery rate in the electrode 23a) is improved, and the power generation efficiency can be improved.

[0043] Furthermore, the electrode 23a in this embodiment does not require special processing of the structure of the electrode 23a, and the cost related to the production of the electrode 23a can be reduced. Also, different from the electrode in a microbial fuel cell, in view of the amount of microorganisms retained on the electrode 23a and the reaction efficiency by the microorganisms, there is no need to increase the size of the electrode 23a, so the equipment related to the gas treatment device can be miniaturized.

[0044] The electrode 23b is the counter electrode of the electrode 23a, is an electrode that transfers electrons to an electron acceptor, and functions as a so-called cathode. Also, the electrode 23b in this embodiment is disposed in the second cell 21b.

[0045] The electrode 23b only needs to function as a cathode, and there are no particular limitations on the material and shape. The material and shape of the electrode 23b can be appropriately selected in view of material procurement, processing costs, the reaction efficiency of the electron acceptor in the electrode 23b, and the like. Examples of the material of the electrode 23b include, for example, carbon and metals (titanium, stainless steel, platinum, copper, etc.) that are widely used as electrode materials in the field of electrochemistry. Examples of the shape of the electrode 23b include, for example, flat plate shape, rod shape, mesh shape, and the like.

[0046] When the electron acceptor supplied into the second cell 21b is a gas (air), one surface of the electrode 23b is in contact with the gas, while the other surface is in contact with the aqueous solution. Therefore, it is preferable that the electrode 23b has a form suitable as a so-called air cathode. Examples of a form suitable as an air cathode include having both gas permeability and water impermeability. By forming the electrode 23b to have gas permeability, it becomes possible to effectively react the gas, which is the electron acceptor, with the electrode 23b. Further, by providing the electrode 23b with water impermeability, it becomes possible to suppress the aqueous solution in the first cell 21a from permeating through the electrode 23b and flowing into the second cell 21b. Specific examples of such an electrode 23b include those made of carbon fibers, and those obtained by performing surface treatment such as coating or film lamination of a material having gas permeability and water impermeability on the surface of a metal mesh. Here, the water impermeability means not allowing water to pass through. For example, waterproofing, water repellency, hydrophobicity, or water stoppage of the electrode 23b is also included in having water impermeability.

[0047] (First Gas Introduction Port) The first gas introduction part 3 is for introducing the gas G containing hydrogen sulfide from the gas generation source to the anode side (the first cell 21a) of the first reaction part 2. Note that the gas generation source in the present invention refers to an environment in which the gas G containing hydrogen sulfide is generated. As specific examples, as described above, facilities and equipment (such as petroleum refining facilities, chemical product manufacturing facilities, drainage and sewage treatment facilities, etc.) and natural environments (volcanic areas, hot spring areas) where the gas G containing hydrogen sulfide is generated can be mentioned.

[0048] The first gas introduction part 3 in the present embodiment may be any one that can introduce the gas G from the gas generation source to the anode side of the first reaction part 2. Here, "introducing the gas G (by the first gas introduction part 3)" also includes introducing the components in the gas G. That is, when introducing the gas G to the anode side of the first reaction part 2 by the first gas introduction part 3, it may be introduced in a gaseous state, or it may be introduced in a state of an aqueous solution in which the gas G is mixed (dissolved). Further, the first gas introduction part 3 in the present embodiment may be directly connected to the gas generation source and introduce the gas G into the first reaction part 2, or may introduce the gas G recovered and temporarily stored from the gas generation source into the first reaction part 2.

[0049] For example, when introducing the gas G in a gaseous state to the anode side of the first reaction part 2, as shown in FIG. 2A, as the first gas introduction part 3, a pipe 31 connecting the gas generation source and the inlet 22a provided in the first cell 21a of the first reaction part 2 can be provided. At this time, by supplying an aqueous solution to the first cell 21a in advance, the gas G introduced in a gaseous state through the first gas introduction part 3 comes into contact with the aqueous solution in the first cell 21a, and the reaction can proceed in a state where hydrogen sulfide in the gas G is dissolved in the aqueous solution.

[0050] Also, for example, when introducing the gas G in a state of an aqueous solution in which the gas G is mixed (dissolved) to the anode side of the first reaction part 2, as the first gas introduction part 3, it can be mentioned that the gas G from the gas generation source is brought into contact with the aqueous solution in the previous stage of the first reaction part 2. As an example of such a first gas introduction section 3, as shown in FIG. 2B, in addition to a pipe 31 for transferring the gas G from the gas generation source, the gas G is introduced through the pipe 31, and there is provided a gas-liquid contact section 32 for bringing the gas G into contact with the aqueous solution, and a water-permeable pipe 33 that connects the gas-liquid contact section 32 and the introduction port 22a and introduces the aqueous solution (gas G mixture) in which the gas G is mixed (dissolved) to the anode side (the first cell 21a) of the first reaction section 2.

[0051] At this time, the gas-liquid contact section 32 may be any one that can mix the gas G from the gas generation source and the aqueous solution, and there are no particular limitations on the shape and material. For example, as an example of the gas-liquid contact section 32, there is one having a water tank in which the aqueous solution is stored, and the gas G is introduced through the pipe 31 so as to come into contact with the aqueous solution in this water tank. At this time, the aqueous solution stored in the water tank may be the same as the aqueous solution supplied into the above-described first cell 21a, or an alkaline solution may be used and a treatment related to so-called wet desulfurization may be used in combination. When using an alkaline solution, in view of the electrode reaction efficiency in the first reaction section 2, it is preferable to use a weakly alkaline aqueous solution. Alternatively, when introducing into the first reaction section 2, means for adjusting the pH may be provided in the subsequent stage of the water tank so that the aqueous solution becomes neutral (around pH 7).

[0052] Also, as another example of the gas-liquid contact section 32, as shown in FIG. 2B, there is one having a tank in which a filler 34 is accommodated, and the gas G is introduced through the pipe 31 from below the tank, while the aqueous solution is supplied from above the tank through an aqueous solution supply section 35. More specifically, a structure known as a gas scrubber can be used. Regarding the aqueous solution supplied through the aqueous solution supply section 35, as described above, the same as the aqueous solution supplied into the first cell 21a or an alkaline solution can be mentioned. Here, the filler 34 may be any one that can enhance the contact efficiency between the gas G and the aqueous solution, and known porous materials or adsorbents can be used. In addition, the means for supplying the aqueous solution to this tank is not limited to the aqueous solution supply unit 35 that supplies the aqueous solution from the outside. For example, it may be provided with a pipe connecting the anode side (the first cell 21a) of the first reaction unit 2 and the gas-liquid contact unit 32, and the aqueous solution (electrolyte solution) may be supplied to the gas-liquid contact unit 32 via the electrolyte solution supply unit 36 that supplies the anode-side electrolyte solution of the first reaction unit 2. Thereby, it becomes possible to reduce the cost related to the water resources used in the first gas introduction unit 3.

[0053] Further, a flow rate adjustment mechanism such as a valve may be provided in the pipe 31 in the first gas introduction unit 3. Thereby, it becomes possible to adjust the amount and flow rate of the gas G (hydrogen sulfide) introduced into the anode side of the first reaction unit 2 and control the mass transfer rate of hydrogen sulfide to the electrode 23a.

[0054] (Second reaction unit) The second reaction unit 4 is for performing power generation treatment or electrolysis treatment by the reaction of hydrogen sulfide remaining in the gas G1 treated in the first reaction unit 2. That is, similar to the first reaction unit 2, the second reaction unit 4 advances an electrode reaction using hydrogen sulfide as an electron donor to recover electric energy and remove the sulfur component in the gas (desulfurization treatment). Hereinafter, the structure of the second reaction unit 4 of the present embodiment will be mainly described from the viewpoint related to power generation treatment. The details of the reactions (treatment steps) related to the power generation treatment and electrolysis treatment by the second reaction unit 4 of the present embodiment will also be described later, similar to the reactions (treatment steps) related to the treatment by the first reaction unit 2.

[0055] FIGS. 3A and 3B are schematic explanatory views showing the second reaction unit and its peripheral structure related to the gas treatment apparatus in the first embodiment of the present invention. Note that FIGS. 3A and 3B show different structures related to the second gas introduction unit 5. Hereinafter, the drawing numbers in the description related to the structures common to FIGS. 3A and 3B are denoted as "FIG. 3".

[0056] As shown in Fig. 3, the second reaction section 4 of the present embodiment includes, within a housing, a first cell 41a, a second cell 41b, an ion exchanger 45 provided so as to partition between the cells 41a and 41b, and a pair of electrodes 43a and 43b respectively disposed in the cells 41a and 41b. Here, the first cell 41a is formed such that the gas G1 processed in the first reaction section 2 is introduced via a second gas introduction section 5 described later, and hydrogen sulfide contained in the gas G1 reacts at the electrode 43a. The electrode 43a disposed in the first cell 41a functions as an anode. On the other hand, the second cell 41b is formed to store or supply an electron acceptor, and the electrode 43b disposed in the second cell 41b functions as a cathode. Further, the electrodes 43a and 43b are connected to an external circuit C2 by a conducting wire. Thereby, in the second reaction section 4, it becomes possible to recover and utilize (power generation process) the electrical energy generated when hydrogen sulfide acts as an electron donor, and to perform desulfurization (electrolysis process) by applying a voltage.

[0057] For example, as shown in Fig. 3, the first cell 41a may include an inlet 42a for introducing the gas G1 via a second gas introduction section 5 described later, a recovery port 42b for recovering the gas after the hydrogen sulfide has undergone an electrode reaction at the electrode 43a and discharging it outside the first cell 41a, and a pipe 46. Further, the pipe 46 may be connected to a gas recovery facility (not shown) to recover and utilize the gas G2. Furthermore, a flow rate adjustment mechanism such as a valve may be provided in the pipe 46 to adjust the timing of recovering the gas G2. Thereby, the gas G2 with a further sulfur component removed from the gas G1 can be efficiently recovered, facilitating discharge outside the system or utilization outside the system.

[0058] The second cell 41b, for example, as shown in FIG. 3, is provided with an electron acceptor supply port 44a for supplying a gaseous electron acceptor (such as oxygen, air, etc.) to the electrode 43b and an electron acceptor discharge port 44b for discharging the gas after the reaction to the second cell 41b. Further, as another example of the second cell 41b, the second cell 41b is provided with a space capable of storing a liquid, and as the electron acceptor supply port 44a and the electron acceptor discharge port 44b, those capable of supplying a solution of the electron acceptor and discharging the solution after the reaction are provided, respectively. Thereby, electrons from the electrode 43a can be received by the electron acceptor via the electrode 43b, and a current flows between the electrode 43a and the electrode 43b to generate electricity. Further, the electron acceptor after the reaction is quickly discharged to the outside of the second reaction part 4 through the electron acceptor discharge port 44b.

[0059] Here, each component in the second reaction part 4 can be the same as the component in the first reaction part 2 described above. That is, the description of the cells 41a and 41b in the second reaction part 4 is replaced with the description of the cells 21a and 21b in the first reaction part 2. Similarly, the description of the inlet 42a, the recovery port 42b, the electrodes 43a and 43b, the electron acceptor supply port 44a, the electron acceptor discharge port 44b, the ion exchanger 45, and the pipe 46 in the second reaction part 4 is replaced with the description of the inlet 22a, the recovery port 22b, the electrodes 23a and 23b, the electron acceptor supply port 24a, the electron acceptor discharge port 24b, the ion exchanger 25, and the pipe 26 in the first reaction part 2.

[0060] (Second Gas Introduction Part) The second gas introduction part 5 is for introducing the gas G1 treated in the first reaction part 2 to the anode side (the first cell 41a) of the second reaction part 4.

[0061] The second gas introduction part 5 in this embodiment only needs to be able to introduce the gas G1 processed by the first reaction part 2 to the anode side of the second reaction part 4. Here, "introducing the gas G1 (by the second gas introduction part 5)" also includes introducing the components in the gas G1. That is, when introducing the gas G1 to the anode side of the second reaction part 4 by the second gas introduction part 5, it may be introduced in a gaseous state, or it may be introduced in a state of an aqueous solution in which the gas G1 is mixed (dissolved). And, as each configuration of the second gas introduction part 5, it can be the same as the configuration of the first gas introduction part 3 described above.

[0062] For example, when introducing the gas G1 in a gaseous state to the anode side of the second reaction part 4, as shown in FIG. 3A, as the second gas introduction part 3, a pipe 51 (shared with the pipe 26) connecting the recovery port 22b provided in the first cell 21a of the first reaction part 2 and the introduction port 42a provided in the first cell 41a of the second reaction part 4 can be provided. At this time, by supplying an aqueous solution to the first cell 41a in advance, the gas G1 introduced in a gaseous state through the second gas introduction part 5 comes into contact with the aqueous solution in the first cell 41a, and the reaction can proceed in a state where hydrogen sulfide in the gas G1 is dissolved in the aqueous solution.

[0063] Also, for example, when introducing the gas G1 in a state of an aqueous solution in which the gas G1 is mixed (dissolved) to the anode side of the second reaction part 4, as the second gas introduction part 5, it can be something that brings the gas G1 into contact with the aqueous solution in the stage before the second reaction part 4. As an example of such a second gas introduction part 5, as shown in FIG. 3B, in addition to the pipe 51 that transfers the gas G1 from the first reaction part 2, the gas G1 is introduced through the pipe 51, and a gas-liquid contact part 52 that makes the gas G1 come into contact with the aqueous solution, and a water-permeable pipe 53 that connects the gas-liquid contact part 52 and the introduction port 42a and introduces the aqueous solution (gas G1 mixture) in which the gas G1 is mixed (dissolved) to the anode side (the first cell 41a) of the second reaction part 4 can be provided.

[0064] At this time, as the gas-liquid contact part 52, the same structure as the above-described gas-liquid contact part 32 can be used. For example, as an example of the gas-liquid contact part 52, there is one that uses a water tank in which an aqueous solution is stored, or as shown in FIG. 3B, it has a tank in which a packing material 54 is accommodated, and gas G1 is introduced from below the tank through a pipe 51, while an aqueous solution is supplied from above the tank through an aqueous solution supply part 55. Note that, similar to the above-described first gas introduction part 3, for the gas-liquid contact part 52 of the second gas introduction part 5, a structure known as a gas scrubber can be used. And for the aqueous solution supplied through the aqueous solution supply part 55, examples include the same aqueous solution as the one supplied into the first cell 41a and an alkaline solution. Also, for the packing material 54, known materials as porous materials or adsorbents can be used. Furthermore, the means for supplying the aqueous solution to this tank is not limited to the aqueous solution supply part 55. For example, it may be provided with a pipe connecting the anode side (first cell 41a) of the second reaction part 4 and the gas-liquid contact part 52, and the aqueous solution (electrolyte solution) is supplied to the gas-liquid contact part 52 through an electrolyte solution supply part 56 that supplies the anode side electrolyte solution of the second reaction part 4. Thereby, it becomes possible to reduce the cost related to the water resources used in the second gas introduction part 5.

[0065] Here, FIGS. 2 and 3 show an example in which a gas-liquid contact part is provided for each reaction part (first reaction part 2 and second reaction part 4), but it is not limited thereto, and one gas-liquid contact part may be shared by a plurality of reaction parts as the gas treatment apparatus 1A. FIG. 4 is a schematic explanatory diagram showing another aspect of the gas treatment apparatus 1A in the present embodiment. As shown in Fig. 4, as another aspect of the gas treatment apparatus 1A, there is an apparatus that includes only a component (corresponding to the gas-liquid contact part 32 described above) connected to the first reaction part 2 as the gas-liquid contact part, and introduces a gas G mixture in which the gas G from the gas generation source is dissolved into the first reaction part 2. Instead of omitting the gas-liquid contact part 52 in the second gas introduction part 5 described above, a water-permeable pipe 57 is provided to introduce the anode-side electrolytic solution (gas G1 mixture) in which the gas G1 generated in the first reaction part 2 is mixed (dissolved) into the anode side (the first cell 41a) of the second reaction part 4. Thus, the gas G1 mixture is introduced into the second reaction part 4 through the pipe 57. Further, the anode-side electrolytic solution (gas G2 mixture) in which the gas G2 generated in the second reaction part 4 is mixed (dissolved) is introduced into the gas-liquid contact part 32 through the pipe 47. At this time, in the gas-liquid contact part 32, the gas G2 mixture is effectively utilized as a water resource in the gas-liquid contact, and the gas G2 is discharged through the pipe 37. In Fig. 4, the above-described aqueous solution supply part 35 is not shown. Thereby, compared with the apparatus in which the gas-liquid contact part is provided in each reaction part in the gas treatment apparatus 1A, the space saving of the entire apparatus becomes possible. Further, by circulating the gas (gas G, gas G1, etc.) introduced into each reaction part in a state of being mixed (dissolved) in the aqueous solution, the components in the gas (particularly reducing substances such as hydrogen sulfide) are introduced into each reaction part in a form (ionized state) suitable for the electrode reaction. Therefore, it is also possible to improve the electrode reaction efficiency in each reaction part.

[0066] The gas treatment apparatus 1A in this embodiment uses hydrogen sulfide in the gas as an electron donor and performs power generation treatment or electrolysis treatment through an electrochemical reaction (electrode reaction). Generally, when performing an electrochemical reaction, there is a problem that the efficiency of the electrochemical reaction decreases due to the movement of electrons to locations other than the actual locations where the electrochemical reaction occurs (the first reaction part 2 and the second reaction part 4). Therefore, it is preferable that the gas treatment apparatus 1A in this embodiment insulates the locations other than the locations where the electrochemical reaction occurs (the first reaction part 2 and the second reaction part 4). As specific examples of the insulation treatment, for example, in addition to installing equipment other than the first reaction part 2 and the second reaction part 4 (such as water tanks in the first gas introduction part 3 and the second gas introduction part 5) on top of an insulator, the outer wall or the inner wall of the first gas introduction part 3 and the second gas introduction part 5 is made of an insulator, or the outer wall or the inner wall of the first gas introduction part 3 and the second gas introduction part 5 is coated with an insulating material. Further, as the insulation treatment of each pipe connected to the reaction part 2, for example, each pipe is made of an insulator, or each pipe is coated with an insulating material.

[0067] In the gas treatment apparatus 1A in the above-described embodiment, power generation treatment or electrolysis treatment can be performed through an electrode reaction using hydrogen sulfide in the gas (gas G and gas G1) as an electron donor. Hereinafter, the reactions (treatment steps) related to the power generation treatment and the electrolysis treatment in the gas treatment apparatus 1A will be described in detail. Note that the following description shows an example of the power generation treatment and the electrolysis treatment in this embodiment, and is not limited thereto. Further, the following description describes the reactions (treatment steps) related to each reaction part (the first reaction part 2 and the second reaction part 4), and the description of the reactions (treatment steps) related to other configurations (such as a gas generation source, the first gas introduction part 3, the second gas introduction part 5, and gas recovery equipment provided at the subsequent stage of the pipe 46) is omitted. Furthermore, the notations of reactions R1 to R7 and steps S1 to S4 are numbered for the purpose of explanation and do not specify the order of the reactions or treatment steps.

[0068] (Reactions (treatment steps) related to power generation treatment and electrolysis treatment in a gas treatment device) First, among the treatments in the gas treatment device 1A of the first embodiment of the present invention, the reaction (treatment step) related to the power generation treatment will be described. The power generation treatment in each reaction part (the first reaction part 2 and the second reaction part 4) of the gas treatment device 1A of the present embodiment refers to a process in which the recovery of electrical energy and the removal (desulfurization) of hydrogen sulfide proceed simultaneously. In addition, the reaction (treatment step) related to the power generation treatment in the gas treatment device 1A of the present embodiment will be described for a case where hydrogen sulfide in a gas (gas G or gas G1) is used as an electron donor and air (oxygen) is used as an electron acceptor.

[0069] For example, when performing power generation treatment in the first reaction part 2 shown in FIG. 2, gas G is introduced into the first cell 21a, which is the anode side in the first reaction part 2, from the gas generation source via the first gas introduction part 3 (step S1). Here, when hydrogen sulfide dissolved in the aqueous solution comes into contact with the electrode 23a in the first cell 21a, hydrogen sulfide quickly functions as an electron donor, and electrons are donated to the electrode 23a. At this time, the reaction (reaction R1) at the electrode 23a is represented by the following reaction formula (formula 1).

Number

[0070] In addition, in the first cell 21a, a part of hydrogen sulfide reacts as hydrogen sulfide ions. The reaction at this time is represented by the following reaction formula (formula 2).

Number

[0071] As shown in formula 1 and formula 2, in reaction R1, hydrogen sulfide donates electrons to the electrode 23a, and hydrogen sulfide itself is detoxified and deodorized by being oxidized.

[0072] Based on the reaction formulas shown in Formula 1 and Formula 2, after the reaction R1 proceeds at the electrode 23a, electrons move from the electrode 23a to the electrode 23b through the conducting wire (reaction R2). At this time, the hydrogen ions generated by the reaction at the electrode 23a move to the second cell 21b side through the ion exchanger 25 (reaction R3).

[0073] On the other hand, air (oxygen) is introduced as an electron acceptor from the electron acceptor supply port 24a into the second cell 21b (step S2). Here, by reaction R2, the electrons that have moved from the electrode 23a to the electrode 23b are received by the electron acceptor through the electrode 23b. Also, at this time, by reaction R3, the hydrogen ions that have moved to the second cell 21b side through the ion exchanger 25 also react with the electron acceptor (oxygen). The reaction (reaction R4) at the electrode 23b at this time is represented by the following reaction formula (Formula 3).

Equation

[0074] Based on the above-described reactions R1 to R4 and steps S1 and S2, an electric current flows between the electrode 23a and the electrode 23b. As a result, the reaction using hydrogen sulfide in the gas G as an electron donor proceeds, and the power generation process (electrical energy recovery and desulfurization process) in the gas treatment apparatus 1A of the present embodiment is performed. The reactions R1 to R4 proceed in the same manner not only in the first reaction unit 2 but also in the second reaction unit 4.

[0075] Then, as the power generation process by the above-described reactions R1 to R4 and steps S1 and S2 proceeds, the gases (gas G, gas G1) introduced into each reaction unit become gases (gas G1, gas G2) in a state where hydrogen sulfide has been removed compared to when they were introduced, and are discharged outside each reaction unit through the recovery ports 22b, 42b and the pipes 26, 46.

[0076] Therefore, by performing power generation processing in each reaction unit of the gas processing apparatus 1A of the present embodiment, power generation for recovering electrical energy is achieved, and at the same time, desulfurization processing and deodorization processing become possible. In addition, even when the gas contains reducing substances (such as ammonia) that are harmful substances or odor substances other than hydrogen sulfide, they similarly function as electron donors, and as the reaction proceeds, detoxification and deodorization become possible.

[0077] Here, the electrical energy obtained by the power generation processing can be recovered and utilized through the external circuit C1 connected to the electrodes 23a and 23b and the external circuit C2 connected to the electrodes 43a and 43b. At this time, in order to recover and utilize the electrical energy, a power storage unit connected to each external circuit may be provided.

[0078] Further, the gas processing apparatus 1A in the present embodiment may be configured to perform only one of power generation processing or electrolysis processing in each reaction unit. However, from the viewpoint of enabling the recovery and utilization of electrical energy, it is preferable to perform power generation processing in at least one of the reaction units. Note that the use of the recovered electrical energy is not particularly limited. For example, it may be used for driving the equipment of the gas processing apparatus, or it may be used outside the gas processing apparatus. In particular, by using it as an energy source related to the equipment drive (apparatus operation) of the gas processing apparatus 1A, it is possible to provide the gas processing apparatus 1A in the present embodiment as a gas processing apparatus capable of energy saving, and in particular, it is possible to provide it as a gas processing apparatus capable of significantly reducing the running cost during continuous processing.

[0079] Next, among the processes in the gas processing apparatus 1A of the first embodiment of the present invention, the reaction (processing step) related to the electrolysis processing will be described. The electrolysis processing in each reaction unit (the first reaction unit 2 and the second reaction unit 4) of the gas processing apparatus 1A of the present embodiment refers to the process in which the removal of hydrogen sulfide by voltage application (desulfurization by electrolysis) proceeds.

[0080] For example, when performing electrolysis in the first reaction unit 2 shown in FIG. 2, gas G is introduced into the first cell 21a on the anode side in the first reaction unit 2 from the gas generation source through the first gas introduction unit 3 (step S3). Here, when a voltage is applied to hydrogen sulfide dissolved in the aqueous solution in the first cell 21a via the external circuit C1 and the electrode 23a, the electrolysis of hydrogen sulfide proceeds. At this time, the reaction (reaction R5) at the electrode 23a is represented by the following reaction formula (formula 4).

Number

[0081] Also, in the first cell 21a, a part of hydrogen sulfide reacts as hydrogen sulfide ions. The reaction at this time is represented by the following reaction formula (formula 5).

Number

[0082] As shown in formula 4 and formula 5, in reaction R5, hydrogen sulfide is detoxified and deodorized by becoming sulfate ions.

[0083] Based on the reaction formulas shown in formula 4 and formula 5, after the reaction R5 at the electrode 23a proceeds, the hydrogen ions generated by the reaction at the electrode 23a move to the second cell 21b side through the ion exchanger 25 (reaction R6).

[0084] On the other hand, air (oxygen) is introduced as an electron acceptor into the second cell 21b from the electron acceptor supply port 24a. Here, due to reaction R6, the hydrogen ions that have moved to the second cell 21b side through the ion exchanger 25 react with the electron acceptor (oxygen). The reaction (reaction R7) at the electrode 23b at this time proceeds according to the same reaction formula as formula 3 described above.

[0085] Based on the above-described reactions R5 to R7 and steps S3 and S4, the electrolysis reaction in which hydrogen sulfide in the gas G becomes sulfate ions proceeds, and the electrolysis treatment (desulfurization treatment) in the gas treatment apparatus 1A of the present embodiment is performed. Note that reactions R5 to R7 proceed in the same manner not only in the first reaction unit 2 but also in the second reaction unit 4.

[0086] Then, as the electrolysis treatment based on the above-described reactions R5 to R7 and steps S3 and S4 proceeds, the gases (gas G, gas G1) introduced into each reaction unit become gases (gas G1, gas G2) in a state where hydrogen sulfide has been removed compared to when they were introduced, and are discharged outside each reaction unit via the recovery ports 22b, 42b and the pipes 26, 46. Note that the reaction rate (reaction efficiency) related to the electrolysis treatment at this time can be adjusted by the applied voltage. Therefore, it is easier to increase the removal efficiency (desulfurization efficiency) of hydrogen sulfide in the electrolysis treatment compared to the power generation treatment.

[0087] As described above, in the gas treatment apparatus 1A according to the present embodiment, since a reaction that directly uses the component (hydrogen sulfide) in the gas G to be treated is performed, the cost related to chemicals (desulfurizing agents, etc.) supplied from outside the system can be significantly reduced compared to dry desulfurization and wet desulfurization. In general, electrode reactions have a high reaction rate, and a lot of knowledge about parameters related to reaction conditions is also known. Therefore, the control of the treatment conditions related to the electrode reaction can be easily performed compared to the control of the treatment conditions related to the treatment using microorganisms. Therefore, in the treatment of a gas containing hydrogen sulfide, a low-cost and stable desulfurization treatment is possible, and at the same time, efficient energy recovery and utilization are possible.

[0088] In addition, in the gas treatment apparatus 1A according to the present embodiment, in each reaction unit (the first reaction unit 2 and the second reaction unit 4), it is not necessary to supply gas components other than those derived from the gas G, and gas generation due to the reaction hardly occurs. Therefore, when the gas G is biogas generated by anaerobic digestion, the gas treatment apparatus 1A according to the present embodiment can effectively remove hydrogen sulfide and other reducing substances in the biogas, and finally it is possible to recover methane gas with high purity as the gas G2.

[0089] Here, the gas treatment apparatus 1A according to the present embodiment is provided with a plurality of reaction units in stages and performs a process (power generation process or electrolysis process) based on an electrode reaction using hydrogen sulfide as an electron donor a plurality of times. However, the combination of the process contents performed in each reaction unit is not particularly limited. For example, after performing a power generation process in the first reaction unit 2, a power generation process may be performed in the second reaction unit 4 as well. That is, it is possible to perform only one of the power generation process or the electrolysis process a plurality of times in each reaction unit. However, as described above, from the viewpoint of effective utilization of electric energy, it is preferable to perform a power generation process in one of the reaction units, and it is more preferable to select a combination of performing a power generation process in the first reaction unit 2 and performing an electrolysis process in the second reaction unit 4. Thereby, in the first reaction unit 2, since a power generation process is performed using a gas (gas G) with a high hydrogen sulfide concentration, the power generation efficiency is high and electric energy can be effectively recovered. Further, the gas (gas G1) with a reduced hydrogen sulfide concentration in the first reaction unit 2 is electrolyzed in the second reaction unit 4, so that it is possible to discharge a gas (gas G2) with an extremely reduced hydrogen sulfide concentration. That is, it is possible to provide a gas treatment apparatus capable of extremely reducing the hydrogen sulfide concentration in the gas while increasing the recovery efficiency of electric energy. More specifically, it is possible to provide a gas treatment apparatus capable of discharging and utilizing a gas (biogas) that satisfies the required value of the hydrogen sulfide concentration (10 ppm or less).

[0090] 〔Second Embodiment〕 FIG. 5 is a schematic explanatory diagram showing a gas processing apparatus according to a second embodiment of the present invention. The gas processing apparatus 1B according to the second embodiment includes a first reaction unit 2 and a second reaction unit 4 in one housing, as compared with the structure of the gas processing apparatus 1A in the first embodiment. Note that the description of the same components as those in the first embodiment will be omitted.

[0091] The gas processing apparatus 1B in the present embodiment has a structure in which the first reaction unit 2 and the second reaction unit 4 have a so-called stacking cell (cell stack). As an example of the gas processing apparatus 1B in the present embodiment, as shown in FIG. 5, in the housing, a first reaction unit 2 including a pair of electrodes 23a and 23b provided on both sides of an ion exchanger 25 and an external circuit C1, and a second reaction unit 4 including a pair of electrodes 43a and 43b provided on both sides of an ion exchanger 45 and an external circuit C2 are formed. Here, in FIG. 5, the left side (the first gas introduction part 3 side) of the electrode 23a is the anode side in the first reaction unit 2, and the right side (the second gas introduction part 5 side) of the electrode 43a is the anode side in the second reaction unit 4. Also, between the electrode 23b and the electrode 43b, it functions not only as the cathode side of the first reaction unit 2 but also as the cathode side of the second reaction unit 4.

[0092] Also in the gas processing apparatus 1B in the present embodiment, similar to the above-described gas processing apparatus 1A, the gas G is introduced into the anode side of the first reaction unit 2 through the first gas introduction part 3, power generation processing or electrolysis processing is performed by the electrodes 23a and 23b, and the gas G1 processed in the first reaction unit 2 is introduced into the anode side of the second reaction unit 4 through the second gas introduction part 5, and power generation processing or electrolysis processing is performed by the electrodes 43a and 43b. Then, the gas G2 processed in the second reaction unit 4 is discharged to the outside of the system.

[0093] In addition, in the gas treatment device 1B, power generation treatment or electrolysis treatment can be performed by the same steps as in the first embodiment, and the combination of treatments in each reaction unit is not particularly limited. However, as described above, it preferably includes power generation treatment, and more preferably, electrolysis treatment is performed in the second reaction unit 4 after power generation treatment is performed in the first reaction unit 2. In the gas treatment device 1B, when different treatments are performed in the first reaction unit 2 and the second reaction unit 4, as described above, since the electrode reaction on the cathode side is represented by the same reaction formula (Formula 3) in both power generation treatment and electrolysis treatment, when storing or supplying a substance that functions as an electron acceptor for hydrogen sulfide between the electrode 23b and the electrode 43b, it is not necessary to use a plurality of substances according to the treatment. That is, in the gas treatment device 1B in the present embodiment, regardless of the treatment content in each reaction unit, the cathode side can be shared at one location.

[0094] In addition, FIG. 5 shows the structure of a stacking cell in which the first reaction unit 2 and the second reaction unit 4 are arranged so as to be an anode-cathode-anode combination as the gas treatment device 1B of the present embodiment. However, the specific structure (the arrangement order of the anode and the cathode) related to the arrangement of the first reaction unit 2 and the second reaction unit 4 is not particularly limited, and a combination other than the structure shown in FIG. 5 may be used.

[0095] As described above, in the gas treatment device 1B of the present embodiment, similar to the gas treatment device 1A, it is possible to efficiently reduce the hydrogen sulfide concentration without increasing the cost related to continuous treatment, and the first reaction unit 2 and the second reaction unit 4 are arranged in one housing. By having the structure of the stacking cell, the configuration related to the cathode side of the first reaction unit 2 and the second reaction unit 4 can be shared, and it is possible to reduce the space occupied by the device.

[0096] 〔Third Embodiment〕 FIG. 6 is a schematic explanatory diagram showing a gas treatment device according to the third embodiment of the present invention. The gas treatment apparatus 1C according to the third embodiment performs electrolysis treatment in at least one of the first reaction unit 2 and the second reaction unit 4, and uses the electrolytic solution W on the anode side after the electrolysis treatment as the electrolytic solution on the cathode side or in another reaction unit. FIG. 6 shows a structure in which the electrolytic solution W generated on the anode side of the second reaction unit 4 is supplied to the cathode side or the anode side of the first reaction unit 2 with respect to the structure of the gas treatment apparatus 1B in the second embodiment. For the components that are the same as those in the second embodiment, the description will be omitted.

[0097] As described above, by the reaction R5, the electrolytic solution W on the anode side after the electrolysis treatment in each reaction unit contains sodium sulfate as an electrolyte and exhibits a liquid property from neutral to acidic. Here, when the electrolytic solution W on the anode side is introduced into the cathode side, the electrode reaction on the cathode side is such that hydrogen ions react with an electron acceptor (oxygen) to generate water. As a result, the electrolytic solution W introduced into the cathode side is neutralized. Thereby, when discharging the used electrolytic solution out of the system, it becomes possible to reduce the chemical cost related to neutralization. Also, as shown in FIG. 6, by introducing an electrolytic solution W to which an alkaline agent is added and discharged from the anode side of the second reaction unit 4, the amount of the electrolytic solution used for the entire apparatus can be reduced, and the running cost can be reduced.

[0098] The gas treatment apparatus 1C in the present embodiment is particularly preferably used when an aqueous solution in which the gas G or the gas G1 is dissolved is supplied to the first reaction unit 2 and / or the second reaction unit 4. When an aqueous solution is supplied to the first reaction unit 2 and / or the second reaction unit 4, the frequency of discharging the electrolytic solution W on the anode side increases as the treatment continues. Therefore, by using the gas treatment apparatus 1C in the present embodiment, the effective utilization of the discharged electrolytic solution W or appropriate treatment (neutralization treatment) related to the discharge of the electrolytic solution W out of the system can be performed, and effective reduction of the running cost becomes possible.

[0099] Note that the gas treatment device 1C in this embodiment is not limited to the configuration shown in FIG. 6. For example, in FIG. 6, electrolysis treatment may be performed in the first reaction unit 2, and the electrolytic solution on the anode side of the first reaction unit 2 may be introduced to the cathode side or the anode side of the second reaction unit 4. As another example, based on the structure of the gas treatment device 1A in the first embodiment, electrolysis treatment is performed in at least one of the first reaction unit 2 and the second reaction unit 4, and the electrolytic solution on the anode side after the electrolysis treatment may be used as the electrolytic solution on the cathode side or in another reaction unit.

[0100] 〔Fourth Embodiment〕 The gas treatment device 1D according to the fourth embodiment is provided with a control unit 6 that controls the treatment in the first reaction unit 2 and / or the second reaction unit 4 based on the hydrogen sulfide concentration in at least one of the gas G containing hydrogen sulfide, the gas G1 treated in the first reaction unit 2, and the gas G2 treated in the second reaction unit 4. FIG. 7 shows the structure of the gas treatment device 1A in the first embodiment with the control unit 6 provided. In FIG. 7, the dashed-dotted arrow indicates that it is controllably or input / output connectably connected. Also, the description of the same components as those in the first embodiment is omitted.

[0101] The gas treatment device 1D in this embodiment selects the treatment content and adjusts the treatment efficiency in the first reaction unit 2 and / or the second reaction unit 4 by the control unit 6 based on the hydrogen sulfide concentration in the treatment path. Here, the control in the control unit 6 includes switching between power generation treatment and electrolysis treatment in the first reaction unit 2 and / or the second reaction unit 4, or voltage control related to the electrolysis treatment in the first reaction unit 2 and / or the second reaction unit 4.

[0102] As shown in FIG. 7, the gas treatment apparatus 1D in this embodiment is provided with a sensor S for measuring the hydrogen sulfide concentration in the gas (gas G, gas G1, gas G2) in the treatment path, and based on the information on the hydrogen sulfide concentration obtained by this sensor S, via the control unit 6, switching of the treatment in each reaction unit (switching via the external circuits C1 and C2) and voltage control related to the electrolysis treatment in each reaction unit (adjustment of the applied voltage via the external circuits C1 and C2) are performed. Although FIG. 7 shows sensors S provided on the paths of the respective gases (gas G, gas G1, gas G2), at least one sensor S is sufficient, and the other sensors S can be omitted.

[0103] As described above, as the treatment in each reaction unit, when the hydrogen sulfide concentration is high, power generation treatment is preferable from the viewpoint that the power generation efficiency is high and electrical energy can be effectively recovered, and when the hydrogen sulfide concentration is low, electrolysis treatment is more preferable than power generation treatment in that the treatment efficiency of hydrogen sulfide can be adjusted by the applied voltage (the hydrogen sulfide concentration can be made lower).

[0104] As an example of the control in the control unit 6, for example, when the hydrogen sulfide concentration in the gas G is measured by the sensor S and the measurement result is higher than the set value, power generation treatment is performed in the first reaction unit 2 via the external circuit C1, or when the hydrogen sulfide concentration in the gas G2 is measured by the sensor S and the measurement result is higher than the required value (for example, 10 ppm), electrolysis treatment is performed in the second reaction unit 4 via the external circuit C2, or when electrolysis treatment has already been performed, increasing the applied voltage, etc. can be mentioned.

[0105] As described above, in the gas treatment apparatus 1D according to the present embodiment, the hydrogen sulfide concentration in any of the gases (gas G, gas G1, gas G2) in the treatment path is measured by the sensor S, and based on the measurement result, the selection of the treatment content in each reaction unit (switching between power generation treatment and electrolysis treatment) or the voltage control related to the electrolysis treatment is performed, thereby improving the efficiency of the treatment of the entire gas treatment apparatus 1D, further improving the recovery efficiency of electrical energy, and more reliably reducing the hydrogen sulfide concentration in the gas to a low concentration.

[0106] Note that the gas treatment apparatus 1D in the present embodiment is not limited to the configuration shown in FIG. 7. For example, a control unit 6 may be provided with respect to the structures of the gas treatment apparatus 1B in the second embodiment and the gas treatment apparatus 1C in the third embodiment to perform control related to the treatment of the first reaction unit 2 and / or the second reaction unit 4.

[0107] Hereinafter, as an aspect of the gas treatment method according to the present invention, an embodiment related to the gas treatment method after a predetermined time has elapsed during continuous treatment using the gas treatment apparatus according to the present invention will be described.

[0108] 〔Fifth Embodiment〕 The fifth embodiment shows an aspect of the gas treatment method of the present invention. FIG. 8 is a schematic explanatory view showing the application of a gas flow path switching step to the gas treatment apparatus 1A in the first embodiment as the fifth embodiment. The gas treatment method in the fifth embodiment includes a first gas introduction step performed via the first gas introduction unit 3 and a gas flow path switching step of switching the gas flow path in the second gas introduction step performed via the second gas introduction unit 5. Then, as shown in FIG. 8, after a predetermined time has elapsed, the gas G containing hydrogen sulfide is introduced into the anode side of the second reaction unit 4 via the second gas introduction unit 5 by the gas flow path switching step, and the gas G3 treated in the second reaction unit 4 is introduced into the anode side of the first reaction unit 2 via the first gas introduction step, and the gas G4 treated in the first reaction unit 2 is discharged to the outside of the system. Here, the gas G3 processed in the second reaction unit 4 shown in FIG. 8 is the gas processed in the first-stage reaction unit, and corresponds to the gas G1 processed in the first reaction unit 2 before switching the gas flow path. Further, the gas G4 processed in the first reaction unit 2 is the gas processed in the second-stage reaction unit, and corresponds to the gas G2 processed in the second reaction unit 4 before switching the gas flow path.

[0109] The gas flow path switching step may be any step that can change the gas flow path in the gas treatment apparatus (in this embodiment, the gas treatment apparatus 1A). For example, as an example of the gas flow path switching step, an operation may be performed to change the gas introduction part connected to the gas generation source from the first gas introduction part 3 (pipe 31) to the second gas introduction part 5 (pipe 51) without adding a new configuration or structure to the gas treatment apparatus 1A. Alternatively, a pipe for transferring gas in the direction opposite to that of the pipes 31 and 51 may be separately provided, and the gas flow path may be switched using the separately provided pipe.

[0110] As described above, the gas treatment apparatus and the gas treatment method of the present invention perform an electrode reaction using hydrogen sulfide as an electron donor in multiple stages (a plurality of reaction units). The hydrogen sulfide concentration in the gas G to be treated is the highest, and the load on the electrode provided in the first reaction unit 2 into which the gas G is introduced is naturally larger than the load on the electrode in the second reaction unit 4 provided in the subsequent stage. Therefore, when the treatment is continuously performed for a long time, there is a concern that the reduction in the treatment efficiency in the first reaction unit 2 will be accelerated. On the other hand, in the present embodiment, due to the gas flow path switching step, after a predetermined time has elapsed, the hydrogen sulfide concentration in the gas introduced into the first reaction unit and the gas introduced into the second reaction unit is appropriately switched, so that continuous treatment can be performed without biasing the load on the electrodes in each reaction unit to one side. Thereby, a decrease in the treatment efficiency in the gas treatment apparatus can be suppressed. Further, the maintenance of the gas treatment apparatus becomes easy, and it is possible to reduce the running cost.

[0111] 〔Sixth Embodiment〕 The sixth embodiment shows one aspect of the gas treatment method of the present invention. FIG. 9 is a schematic explanatory diagram showing, as the sixth embodiment, the gas treatment apparatus 1A in the first embodiment to which an electrode replacement process is applied. Further, FIG. 10 is a schematic explanatory diagram showing another aspect in the sixth embodiment. The gas treatment method in the sixth embodiment includes an electrode replacement process in which, after a predetermined time has elapsed, the electrodes in one of the first reaction unit 2 and the second reaction unit 4 are replaced with new electrodes, and the used electrodes after replacement are used as the electrodes in the other reaction unit.

[0112] The electrode replacement process in the present embodiment relates to operations related to the selection and replacement of the electrodes to be replaced in the gas treatment apparatus (gas treatment apparatus 1A in the present embodiment). Instead of replacing all the electrodes in each reaction unit at once, only the electrodes in one reaction unit are replaced with new electrodes, and the replaced used electrodes are used in the other reaction unit.

[0113] As one specific example of the electrode replacement process, as shown in FIG. 9, the electrodes 43a and 43b of the second reaction unit 4 are replaced with new electrodes, and the replaced used electrodes (electrodes 43a and 43b) are replaced with the electrodes 23a and 23b of the first reaction unit 2. Thereby, in the second reaction unit 4, it is possible to maintain and improve the electrode reaction efficiency with the new electrodes. On the other hand, as described above, in the second reaction unit 4 which is the second-stage reaction unit, the load on the electrodes is less than that in the first reaction unit 2 which is the first-stage reaction unit. Therefore, at the timing of replacing the electrodes, the performance degradation of the electrodes 43a and 43b in the second reaction unit 4 does not progress as much as that of the electrodes 23a and 23b in the first reaction unit 2. That is, by exchanging the electrodes 23a and 23b in the first reaction unit 2 with the used electrodes 43a and 43b in the second reaction unit 4, the electrodes 43a and 43b can be effectively utilized, and it is possible to reduce the frequency of electrode replacement for the entire apparatus.

[0114] As another example of the electrode replacement process, as shown in FIG. 10, the electrodes 23a and 23b of the first reaction section 4 are replaced with new electrodes, and the replaced used electrodes (electrodes 23a and 23b) are replaced with the electrodes 43a and 43b of the second reaction section 4. Thereby, in the first reaction section 2, it is possible to maintain and improve the electrode reaction efficiency with the new electrodes. Here, since the gas G with a relatively high hydrogen sulfide concentration is introduced into the first reaction section 2, the power generation process is often selected. Also, as described above, when the power generation process is performed in the reaction section, sulfur is generated by the reaction R1 (Equations 1 and 2), so sulfur may adhere to the used electrodes (electrodes 23a and 23b) used in the first reaction section 2. On the other hand, in the second reaction section 4, which is the second-stage reaction section, since the gas G1 with a relatively low hydrogen sulfide concentration is introduced, the electrolysis process is often selected, and this electrolysis process can also remove the sulfur adhering to the electrodes. That is, by performing the electrolysis process using the electrodes 23a and 23b to which sulfur has adhered in the second reaction section 4, it is possible to simultaneously perform the cleaning (sulfur removal) of the electrodes in addition to the removal of hydrogen sulfide.

[0115] As described above, instead of replacing all the electrodes in each reaction section at once, by the electrode replacement process, the electrodes to be replaced with new electrodes are selected, and the replaced used electrodes are used in the other reaction section, so that it is possible to maintain and improve the electrode reaction efficiency with the new electrodes and reduce the maintenance cost based on the reuse of the used electrodes (such as reducing the frequency of electrode replacement and the cost related to electrode cleaning), and it is possible to achieve both the efficient reduction of the hydrogen sulfide concentration and the reduction of the running cost.

[0116] Note that the above-described embodiments show an example of the gas treatment apparatus and the gas treatment method. The gas treatment apparatus and the gas treatment method according to the present invention are not limited to the above-described embodiments, and the gas treatment apparatus and the gas treatment method according to the above-described embodiments may be modified without changing the gist described in the claims.

[0117] For example, the gas treatment apparatus in the present embodiment may be provided with means for preventing the adhesion and deposition of microorganisms on each electrode (electrodes 23a, 23b, 43a, 43b). Examples of such means include coating the electrode surface with a material that prevents the adhesion of microorganisms, or making the shape of the electrode structure itself such that it is difficult for microorganisms to adhere. This makes it possible to suppress the inhibition of the electrode reaction by microorganisms even when microorganisms flow into each reaction part (especially the first reaction part 2).

[0118] Also, for example, the gas treatment apparatus in the present embodiment may omit some structures to simplify the apparatus configuration. Examples of the structures that can be omitted include, for example, the ion exchangers 25 and 45. This makes it possible to simplify the first reaction part 2 and the second reaction part 4, and also makes the maintenance work easier. Also, as another example of the structures that can be omitted, the electron acceptor supply ports 24a, 44a and the electron acceptor discharge ports 24b, 44b in the second cells 21b, 41b in each reaction part can be cited. This makes it possible to further simplify the first reaction part 2 and the second reaction part 4. At this time, examples include a structure in which one surface of the electrodes 23b, 43b is in contact with the aqueous solution or the ion exchangers 25, 45 in the first cells 21a, 41a, and the other surface is in direct contact with the outside air (air) as a whole. Furthermore, it is preferable to provide a breathable material that is easy to exchange or clean on the surfaces of the electrodes 23b, 43b on the outside air side. This can suppress the adhesion of solid impurities such as dust to the surfaces of the electrodes 23b, 43b.

[0119] Further, for example, the gas treatment apparatus and the gas treatment method in the present embodiment may have at least two or more reaction units (reaction steps) and may perform multi-stage treatment. For the first reaction unit 2 and the second reaction unit 4, further reaction units may be added, and it may be composed of three or more reaction units. In particular, as shown for the gas treatment apparatus 1B of the second embodiment, in terms of the ease of providing a plurality of reaction units in the housing, it is preferable to have a structure including three or more reaction units also from the viewpoint of the ease of providing a plurality of reaction units in the housing. Thereby, the treatment capacity for hydrogen sulfide can be improved, and the hydrogen sulfide concentration in the gas can be extremely reduced regardless of the properties of the gas G from the gas generation source (hydrogen sulfide concentration, types and concentrations of gas components other than hydrogen sulfide contained therein, etc.).

[0120] Furthermore, the configuration of the gas treatment apparatus in the present embodiment may be used independently or may be combined with other treatment facilities to construct a treatment system. Furthermore, it may be applied as a gas treatment apparatus in an existing treatment system. Thereby, a treatment system including the gas treatment apparatus of the present invention having power generation treatment or electrolysis treatment functions can be easily provided. In addition, it is possible to provide a gas treatment method (including a power generation method or a desulfurization method) using the gas treatment apparatus of the present invention for a newly constructed treatment system or an existing treatment system.

Industrial Applicability

[0121] The gas treatment apparatus and the gas treatment method of the present invention are used for treating a gas containing hydrogen sulfide generated from gas generation sources such as petroleum refining facilities, natural gas refining facilities, coke manufacturing facilities, hydrogen manufacturing facilities, tire manufacturing facilities, kraft pulp manufacturing facilities, solid battery manufacturing facilities, waste treatment facilities, drainage / sewage treatment facilities, and hot spring areas. In particular, it is preferably used in gas treatment when hydrogen sulfide is contained in biogas generated by anaerobic digestion treatment.

Explanation of Reference Numerals

[0122] 1A, 1B, 1C, 1D gas treatment apparatus, 2 first reaction section, 21a first cell, 21b second cell, 22a inlet, 22b recovery port, 23a, 23b electrodes, 24a electron acceptor supply port, 24b electron acceptor discharge port, 25 ion exchanger, 26 pipe, 3 first gas introduction section, 31 pipe, 32 gas-liquid contact section, 33 pipe, 34 packing material, 35 aqueous solution supply section, 36 electrolyte supply section, 37 pipe, 4 second reaction section, 41a first cell, 41b second cell, 42a inlet, 42b recovery port, 43a, 43b electrodes, 44a electron acceptor supply port, 44b electron acceptor discharge port, 45 ion exchanger, 46, 47 pipes, 5 second gas introduction section, 51 pipe, 52 gas-liquid contact section, 53 pipe, 54 packing material, 55 aqueous solution supply section, 56 electrolyte supply section, 57 pipe, 6 control section, C1, C2 external circuits, G gas containing hydrogen sulfide, G1, G3 gas from which hydrogen sulfide has been removed (in the first-stage reaction section), G2, G4 gas from which hydrogen sulfide has been removed (in the second-stage reaction section), S hydrogen sulfide concentration sensor, W electrolyte

Claims

1. A gas treatment apparatus for treating a gas containing hydrogen sulfide, comprising: a first reaction section having a pair of electrodes; a second reaction section having a pair of electrodes; a first gas introduction section for introducing a gas containing hydrogen sulfide to the anode side of the first reaction section; a second gas introduction section for introducing the gas treated in the first reaction section to the anode side of the second reaction section, wherein the first reaction section and the second reaction section perform power generation treatment and / or electrolysis treatment.

2. The gas treatment apparatus according to claim 1, wherein power generation treatment is performed in the first reaction section and electrolysis treatment is performed in the second reaction section.

3. The gas treatment apparatus according to claim 1 or 2, wherein electrolysis treatment is performed in at least one of the first reaction section and the second reaction section, and the electrolytic solution on the anode side after the electrolysis treatment is used as the electrolytic solution in the cathode side or another reaction section.

4. A control section for controlling the treatment of the first reaction section and / or the second reaction section based on the hydrogen sulfide concentration in at least one of the gas containing hydrogen sulfide, the gas treated in the first reaction section, and the gas treated in the second reaction section, wherein the control in the control section includes switching between power generation treatment and electrolysis treatment in the first reaction section and / or the second reaction section, or voltage control related to electrolysis treatment in the first reaction section and / or the second reaction section.

5. The gas treatment apparatus according to claim 1 or 2, wherein power generation treatment is performed in at least one of the first reaction section and / or the second reaction section, and the electrical energy obtained by the power generation treatment is used as an energy source for the operation of the apparatus.

6. A gas treatment method for treating a gas containing hydrogen sulfide, comprising: a first gas introduction step of introducing a gas containing hydrogen sulfide to the anode side of a first reaction section having a pair of electrodes; a first reaction step of performing power generation treatment or electrolysis treatment in the first reaction section; a second gas introduction step of introducing the gas treated in the first reaction step to the anode side of a second reaction section having a pair of electrodes; a second reaction step of performing power generation treatment or electrolysis treatment in the second reaction section.

7. A gas flow path switching step of switching the gas flow path in the first gas introduction step and the second gas introduction step. After a predetermined time has elapsed, by the gas flow path switching step, the gas containing hydrogen sulfide is introduced into the second reaction section through the second gas introduction step, and the gas treated in the second reaction section is introduced into the first reaction section through the first gas introduction step. The gas treatment method according to claim 6, characterized in that.

8. After a predetermined time has elapsed, an electrode exchange step of replacing an electrode in one of the first reaction section and the second reaction section with a new electrode, and using the used electrode after replacement as an electrode in the other reaction section. The gas treatment method according to claim 6, characterized in that it comprises.

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