Gas processing device, and gas processing method

Abstract

To provide a gas processing device and method that simply carry out continuous monitoring without increasing costs when performing efficient gas processing, in the gas processing device and gas processing method for processing hydrogen sulfide-containing gas by carrying out an electrode reaction with the hydrogen sulfide as an electron donor.SOLUTION: Provided are a gas processing device and gas processing method using the device that comprise: a reaction unit that has a pair of electrodes; a gas introduction part that introduces hydrogen sulfide-containing gas to the reaction unit on an anode side; a gas-liquid contact part to which an anode solution discharged from the reaction unit is introduced; a gas concentration measurement unit that measures hydrogen sulfide gas concentration discharged from the gas-liquid contact part; and a fluctuation detection unit that detects a fluctuation component in an electrolytic solution in the reaction unit on the basis of the hydrogen sulfide gas concentration measured by the gas concentration measurement unit. According to the present invention, continuous monitoring for gas processing can be performed, without using a pH meter.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 for naturally occurring gases and gases generated in various treatment processes in view of effective utilization of the gas and its 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 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 regular replacement of the desulfurizing agent and use of a large amount of chemicals, and high costs for treating a large amount of waste generated after the treatment.

[0004] In recent years, as one of the desulfurization treatments, so-called biological desulfurization using microorganisms has attracted attention. Biological desulfurization is a process in which a gas to be treated (a gas containing hydrogen sulfide) is brought into contact with microorganisms through a packed bed carrying the microorganisms, and hydrogen sulfide in the gas is oxidized. Therefore, the treatment by biological desulfurization is expected to be able to treat at a low running cost with less costs related to the use of desulfurizing agents, chemicals, etc. and costs related to the treatment of waste generated after the treatment, as compared with 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] On the other hand, the 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. In the course of repeated studies, the inventor has found that in gas treatment using an electrode reaction with hydrogen sulfide as an electron donor, in order to perform efficient gas treatment, it is important to efficiently dissolve hydrogen sulfide gas in the electrolytic solution. Furthermore, since the solubility of hydrogen sulfide gas in the solution depends on pH, it has been found that continuous information acquisition regarding pH fluctuations in the electrolytic solution is important.

[0009] Here, as a means for continuously acquiring information regarding pH fluctuations, it is common to use a pH meter. However, hydrogen sulfide is a substance with high corrosiveness and is known to have a property of accelerating corrosion particularly when coexisting with water. Therefore, when continuously acquiring information regarding pH fluctuations in the electrolytic solution, there is a problem that the replacement frequency of the pH meter becomes high when using a pH meter.

[0010] Also, in general gas treatment, for information acquisition related to gas treatment efficiency and appropriate device operation, so-called monitoring, it is desired to be able to continue at low cost and simply.

[0011] Therefore, 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 perform efficient gas treatment without increasing costs and can easily perform continuous monitoring.

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, a gas-liquid contact treatment is performed in combination with an electrode reaction using hydrogen sulfide as an electron donor, and the electrolytic solution after the electrode reaction is introduced into the gas-liquid contact treatment side, and monitoring related to gas treatment is performed based on the concentration of hydrogen sulfide gas discharged therefrom, so that efficient gas treatment can be performed without increasing costs and continuous monitoring can be easily performed. Based on this finding, the present invention has been completed. That is, the present invention relates to 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 reaction part having a pair of electrodes, a gas introduction part for introducing a gas containing hydrogen sulfide to the anode side of the reaction part, a gas-liquid contact part into which the anode solution discharged from the reaction part is introduced, a gas concentration measurement part for measuring the concentration of hydrogen sulfide gas discharged from the gas-liquid contact part, and a variation detection part for detecting a change in the components in the electrolytic solution in the reaction part based on the concentration of hydrogen sulfide gas measured by the gas concentration measurement part. In the gas treatment apparatus of the present invention, a gas containing hydrogen sulfide is introduced to the anode side of a reaction part having a pair of electrodes, and an electrode reaction using hydrogen sulfide contained in the gas as an electron donor is allowed to proceed, so that power generation treatment or desulfurization treatment by electrolysis treatment using hydrogen sulfide becomes possible. Thereby, treatment can be performed at a lower cost compared to general dry desulfurization and wet desulfurization, and control of stable treatment conditions is easier compared to biological desulfurization. Therefore, in the treatment of a gas containing hydrogen sulfide, it is possible to continuously perform low-cost and stable desulfurization treatment. Further, the gas treatment apparatus of the present invention introduces the anode solution (the electrolytic solution on the anode side after the electrode reaction) discharged from the reaction section into the gas-liquid contact section, and measures the concentration of hydrogen sulfide gas contained in the gas discharged therefrom. Here, the present inventor has obtained the finding that the concentration of hydrogen sulfide gas measured at this time is related to the component variation in the electrolytic solution in the reaction section. Based on this finding, in the gas treatment apparatus of the present invention, by detecting the component variation in the electrolytic solution from the measured hydrogen sulfide gas concentration, monitoring related to gas treatment without relying on a pH meter becomes possible. That is, with the gas treatment apparatus of the present invention, continuous monitoring related to gas treatment can be carried out simply and without increasing costs when performing efficient gas treatment.

[0014] Also, as an embodiment of the gas treatment apparatus of the present invention, the variation detection unit is characterized by detecting a variation related to the hydrogen ion concentration or the hydrogen sulfide ion concentration in the electrolytic solution. As described above, the present inventor has obtained the finding that when the anode solution discharged from the reaction section is introduced into the gas-liquid contact section and then the concentration of hydrogen sulfide gas in the gas discharged from the gas-liquid contact section is measured, the concentration of hydrogen sulfide gas measured at this time is related to the component variation in the electrolytic solution in the reaction section. More specifically, the concentration of hydrogen sulfide gas measured at this time is related to the amount of hydrogen sulfide discharged without undergoing an electrode reaction in the reaction section, and further related to the component variation in the electrolytic solution (especially the electrolytic solution on the anode side) in the reaction section. Here, the amount (concentration) of hydrogen sulfide discharged without undergoing an electrode reaction is greatly affected by the variation in the hydrogen sulfide ion concentration in the electrolytic solution and the variation in the hydrogen ion concentration in the electrolytic solution, that is, the pH variation. Therefore, in the gas treatment apparatus of the present invention, based on the measured hydrogen sulfide gas concentration, by detecting fluctuations in the components in the electrolytic solution, particularly fluctuations related to the hydrogen ion concentration or hydrogen sulfide ion concentration in the electrolytic solution, it becomes possible to obtain (monitor) information that greatly affects the gas treatment efficiency. In particular, it becomes possible to obtain information related to pH fluctuations during gas treatment by simple means other than a pH meter. As a result, in the gas treatment apparatus of the present invention, it is possible to improve the monitoring accuracy without increasing the cost associated with continuous monitoring required for efficient gas treatment.

[0015] Further, as an embodiment of the gas treatment apparatus of the present invention, it is characterized by including a pH adjustment unit that adjusts the pH of the electrolytic solution based on the detection result of the fluctuation detection unit. According to this feature, it becomes possible to optimize the pH, which is a factor affecting the gas treatment efficiency, based on the detection result of the fluctuation detection unit, that is, the result of monitoring related to gas treatment. As a result, it becomes easy to continue efficient gas treatment in conjunction with the monitoring related to gas treatment.

[0016] Further, as an embodiment of the gas treatment apparatus of the present invention, it is characterized by including an abnormality determination unit that determines the presence or absence of an operation abnormality based on the detection result of the fluctuation detection unit. According to this feature, based on the detection result of the fluctuation detection unit, that is, the result of monitoring related to gas treatment, it becomes possible to grasp that a situation that needs to be addressed has occurred regarding the operation of the gas treatment apparatus. As a result, in conjunction with the monitoring related to gas treatment, it becomes easy to make a determination and take measures for appropriately continuing efficient gas treatment.

[0017] Further, as an embodiment of the gas treatment apparatus of the present invention, the abnormality determination unit is characterized by determining the presence or absence of an operation abnormality based on the detection result of the fluctuation detection unit and the result of the electrode reaction in the reaction unit. According to this feature, by considering not only the component variations in the electrolytic solution but also the results of the electrode reactions, it becomes possible to determine whether the abnormal operation of the gas treatment device is caused by component variations in the electrolytic solution or by the electrode side of the reaction section. As a result, it becomes even easier to quickly and accurately take measures to appropriately continue efficient gas treatment in conjunction with the monitoring related to gas 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 gas introduction step of introducing a gas containing hydrogen sulfide to the anode side of a reaction section having a pair of electrodes; a reaction step of performing an electrode reaction in the reaction section; a gas-liquid contact step of introducing an anode solution discharged from the reaction section; a gas concentration measurement step of measuring the hydrogen sulfide gas concentration discharged from the gas-liquid contact step; and a variation detection step of detecting component variations in the electrolytic solution in the reaction step based on the hydrogen sulfide gas concentration measured in the gas concentration measurement step. The gas treatment method of the present invention introduces a gas containing hydrogen sulfide to the anode side of a reaction section having a pair of electrodes, and by promoting an electrode reaction using hydrogen sulfide contained in the gas as an electron donor, desulfurization treatment by power generation treatment or electrolytic treatment using hydrogen sulfide becomes possible. As a result, it is possible to perform the treatment at a lower cost compared to general dry desulfurization and wet desulfurization, and it becomes easier to control stable treatment conditions compared to biological desulfurization. Therefore, in the treatment of a gas containing hydrogen sulfide, it becomes possible to continuously perform low-cost and stable desulfurization treatment. Further, in the gas treatment method of the present invention, the anode solution discharged from the reaction section is introduced into the gas-liquid contact step, and the concentration of hydrogen sulfide gas contained in the gas discharged therefrom is measured. Then, based on the finding of the present inventor that the concentration of hydrogen sulfide gas measured at this time is related to the component variation in the electrolytic solution in the reaction section, in the gas treatment method of the present invention, by detecting the component variation in the electrolytic solution from the measured concentration of hydrogen sulfide gas, monitoring related to gas treatment without relying on a pH meter becomes possible. That is, by the gas treatment method of the present invention, in performing efficient gas treatment, continuous monitoring related to gas treatment can be performed simply without increasing costs.

Effects of the Invention

[0019] 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 capable of performing continuous monitoring simply without increasing costs when performing efficient gas treatment.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0021] Hereinafter, embodiments of a gas treatment apparatus and a gas treatment method according to the present invention will be described in detail with reference to the drawings. The description related to 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 gas treatment method described in the embodiments are merely examples for explaining the gas treatment apparatus and gas treatment method according to the present invention, and are not limited thereto.

[0022] In the gas treatment apparatus and 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, gases naturally generated such as volcanic gas, gases generated during various processing processes such as petroleum refining and chemical product manufacturing, and gases generated during 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 methane fermentation treatment. Generally, biogas generated by methane fermentation treatment contains hydrogen sulfide in addition to methane that can be effectively utilized as a fuel, so 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) such as biological desulfurization to the location (anode side of the reaction section) where the gas containing hydrogen sulfide is introduced and reacted. For this reason, there is an advantage that it is possible to recover and utilize the gas as high-purity methane gas without air (oxygen) being mixed into the gas after desulfurization treatment.

[0023] Specific examples of the gas generation source from which 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.

[0024] 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 determined relatively by its 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 with 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 or mixtures containing oxygen, and the like. In addition, 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 and ammonia.

[0025] 〔First Embodiment〕 FIG. 1 is a schematic explanatory diagram showing the structure of a gas treatment apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the gas treatment apparatus 1A in the present embodiment includes a reaction unit 2, a gas introduction unit 3, a gas-liquid contact unit 4, a gas concentration measurement unit 5, and a variation detection unit 6. In FIG. 1, the dashed arrow indicates that they are connected so as to be inputtable and outputtable.

[0026] The gas treatment apparatus 1A shown in FIG. served as an electron donor is caused to proceed, a desulfurization treatment (power generation treatment or electrolysis treatment) is performed. The gas that is insoluble in water generated at this time (a part of the sulfur component is removed from the gas G, and the gas that is insoluble in water, hereinafter also simply referred to as "gas G1") is discharged to the outside of the system. Further, the anode solution S discharged from the reaction unit 2 A(The electrolytic solution on the anode side after the electrode reaction) is introduced into the gas-liquid contact part 4 and used as an aqueous solution in the gas-liquid contact part 4. On the other hand, the hydrogen sulfide gas concentration in the gas (hereinafter referred to as "gas G2") discharged from the gas-liquid contact part 4 is measured by the gas concentration measuring part 5. Then, the measurement result of the gas concentration measuring part 5 is input into the fluctuation detecting part 6, and the fluctuation detecting part 6 detects the component fluctuation in the electrolytic solution in the reaction part 2. Hereinafter, the details of each component of the gas treatment device 1A will be described. In the following description, "anode solution S" A " specifically refers to the electrolytic solution on the anode side after the electrode reaction. When simply referred to as "electrolytic solution", it refers to the entire solution contained in the reaction part 2 regardless of before and after the electrode reaction, including the gas G mixture.

[0027] (Reaction part) The reaction part 2 is for performing power generation treatment or electrolysis treatment by the reaction of hydrogen sulfide in the gas G containing hydrogen sulfide. More specifically, the reaction part 2 is for promoting an electrode reaction using hydrogen sulfide as an electron donor to recover electrical energy and remove the sulfur component in the gas (desulfurization treatment). Hereinafter, the structure of the reaction part 2 of the present embodiment will be described mainly from the viewpoint related to the power generation treatment. The details of the reactions (treatment steps) related to the power generation treatment and electrolysis treatment by the reaction part 2 of the present embodiment will be described later.

[0028] As shown in FIG. 1, the reaction section 2 of the present embodiment includes, within 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 in the cells 21a and 21b. Here, the first cell 21a is formed such that gas G (gas G mixture) is introduced through a gas introduction section 3 described later, and hydrogen sulfide contained in the gas G reacts at the electrode 23a. The electrode 23a disposed in the first cell 21a functions as an anode. On the other hand, the second cell 21b is formed so as to store or supply an electron acceptor, and the electrode 23b disposed in the second cell 21b functions as a cathode. Further, the electrodes 23a and 23b are connected to an external circuit C by conducting wires. Thereby, in the reaction section 2, 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.

[0029] The first cell 21a only needs to include the electrode 23a and be connected to the gas introduction section 3, and be formed such that hydrogen sulfide in the gas G reacts at the electrode 23a, and there are no particular restrictions on the material or shape. Here, in the reaction section 2 of the present embodiment, in order to efficiently and stably advance the electrode reaction using hydrogen sulfide as an electron donor, in the first cell 21a, it is necessary to accommodate hydrogen sulfide in the gas G introduced through the gas introduction section 3 in a state dissolved in an aqueous solution. For this reason, as the first cell 21a, for example, as shown in FIG. 1, it can be mentioned that it has a structure having a space capable of temporarily storing the gas G and the aqueous solution introduced from the introduction port 22a through the gas introduction section 3.

[0030] Further, 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, (a part of) the sulfur component is removed from the gas G containing hydrogen sulfide, and the gas G1 insoluble in water (electrolyte solution) 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. 1, 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. 1, it is preferable to provide the recovery port 22b on the upper surface of the first cell 21a.

[0031] In addition, when all the products generated by the electrode reaction in the reaction section 2 and the components introduced through the gas introduction section 3 are substances that can dissolve in water (electrolyte solution), the recovery port 22b and the pipe 26 can be omitted. Further, the recovery port 22b and the pipe 26 may be integrated with the recovery port 22c and the pipe 27 described later, and the gas G1 and the anode solution S A may be introduced into the gas-liquid contact section 4 together. Thereby, since the gas G1 is further gas-treated by the gas-liquid contact section 4, it becomes possible to obtain a gas with high purity.

[0032] The means for storing the aqueous solution in the first cell 21a is not particularly limited. For example, the aqueous solution may be supplied to the first cell 21a in advance before the operation of the gas treatment apparatus 1A, or the aqueous solution may be supplied through the gas introduction section 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.

[0033] The first cell 21a contains an anode solution S, which is an electrolytic solution obtained after hydrogen sulfide undergoes an electrode reaction at the electrode 23a. A and introduce it into the gas-liquid contact section 4, which will be described later. This allows the anode solution S, which contains products of the electrode reaction and unreacted substances derived from the gas G containing hydrogen sulfide, to be collected. A functions as the aqueous solution in the gas-liquid contact section 4. The anode solution S introduced into the gas-liquid contact section 4 A Among the products and unreacted substances contained in the gas, those (gas G2) discharged as gas in the gas-liquid contact section 4 are to be measured by the gas concentration measuring section 5 described later. In this case, the position of recovery port 22c is not particularly limited. For example, as shown in Fig. 1, recovery port 22c may be provided on the side surface of first cell 21a and at a position vertically higher than inlet 22a, or recovery port 22c may be provided at a position vertically lower than inlet 22a, or recovery port 22c may be provided on the bottom surface of first cell 21a.

[0034] The second cell 21b may be any cell as long as it is provided with an electrode 23b and is configured to store or supply an electron acceptor for hydrogen sulfide, and there are no particular restrictions on the material or shape.

[0035] Here, the electron acceptor may be in the form of either a gas or a liquid. The liquid may be a solution in which a solid drug is dissolved, or a solution in which a gas is mixed (dissolved). Specific examples of the electron acceptor in this embodiment include gases such as oxygen and oxygen-containing gases. Examples of oxygen-containing gases include 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 in that disposal of the gas discharged after the reaction is unnecessary (or easy), and that the cost of obtaining the gas can be reduced. To maximize these advantages, it is particularly preferable to use air as the electron acceptor. In addition, in this embodiment, as other examples of the electron acceptor, for example, as a liquid, a solution containing dissolved oxygen, an aqueous solution of an oxidizing agent such as an aqueous solution of potassium ferricyanide, etc. may be mentioned. When a liquid is used as the electron acceptor, since it becomes 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.

[0036] As the second cell 21b, for example, as shown in FIG. 1, in order to supply a gaseous electron acceptor (oxygen, air, etc.) to the electrode 23b in the second cell 21b, 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. 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, etc. can be mentioned. 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 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 becomes 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.

[0037] In FIG. 1, 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, water is generated by the reaction at the electrode 23b as will be described later. 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.

[0038] The ion exchanger 25 may have any known configuration that can permeate ions 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. Thereby, 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. Thereby, it is possible to suppress the movement of the electron acceptor (oxygen) supplied to the electrode 23b (cathode side) to the electrode 23a side, and it is possible to suppress the reduction in the reaction efficiency of the electron donor at the electrode 23a due to oxygen. In FIG. 1, the ion exchanger 25 is shown as being provided separately from the electrodes 23a and 23b, but the present invention is not limited thereto. For example, a material having ion exchange ability and the electrodes 23a and / or 23b may be integrated. Thereby, it is possible to reduce the size of the entire reaction section 2 and to shorten the time required for maintenance work.

[0039] 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. 1, 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.

[0040] As the electrode 23a, any electrode that functions as an anode may be used, and the material and shape are not particularly limited. The material and shape of the electrode 23a can be appropriately selected in consideration of factors such as material procurement costs, processing costs, and the reaction efficiency of reducing substances in the electrode 23a. 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, flat plate shape, rod shape, mesh shape, etc.

[0041] The electrode 23a in the present embodiment reacts using hydrogen sulfide as a direct electron donor, and 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 microorganisms. Therefore, the mass transfer of hydrogen sulfide to the surface of the electrode 23a is not inhibited by 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 the present 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-determining, 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.

[0042] Furthermore, in the present embodiment, the electrode 23a 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, unlike the electrode in a microbial fuel cell, there is no need to increase the size of the electrode 23a in consideration of the retention amount of microorganisms on the electrode 23a and the reaction efficiency by microorganisms, so the equipment related to the gas treatment device can be miniaturized.

[0043] 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. Further, the electrode 23b in the present embodiment is disposed in the second cell 21b.

[0044] The electrode 23b may be any electrode that functions 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 consideration of material procurement, processing costs, 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, a flat plate shape, a rod shape, a mesh shape, and the like.

[0045] 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, the electrode 23b preferably 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 fiber, 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, and for example, waterproofing, water repellency, hydrophobization, or water stoppage of the electrode 23b is also included in having water impermeability.

[0046] (Gas introduction part) The gas introduction section 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 reaction section 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. Specific examples include facilities and equipment (such as petroleum refining facilities, chemical product manufacturing facilities, drainage and sewage treatment facilities) and natural environments (volcanic areas, hot spring areas) where the gas G containing hydrogen sulfide is generated, as described above.

[0047] The gas introduction section 3 only needs to be able to introduce the gas G from the gas generation source to the anode side of the reaction section 2. Here, "introducing the gas G (by the gas introduction section 3)" also includes introducing the components in the gas G. That is, when introducing the gas G to the anode side of the reaction section 2 by the gas introduction section 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). Also, the gas introduction section 3 may be directly connected to the gas generation source and introduce the gas G to the reaction section 2, or it may introduce the gas G recovered and temporarily stored from the gas generation source to the reaction section 2.

[0048] Here, in the gas treatment apparatus 1A of the present embodiment, the hydrogen sulfide contained in the gas G is desulfurized (power generation treatment or electrolysis treatment) by the electrode reaction in the reaction section 2. At this time, as will be described later, the electrode reaction proceeds by allowing the reaction to proceed in a state where hydrogen sulfide is dissolved in the aqueous solution, and the reaction also proceeds as hydrogen sulfide in an ionic state (hydrogen sulfide ion). And hydrogen sulfide in an uncharged state (H2S) has a lower ability to act as an electron donor compared to ionized hydrogen sulfide (hydrogen sulfide ion: HS - ) and the electrode reaction efficiency in the reaction section 2 is significantly reduced. Therefore, it is preferable that the hydrogen sulfide introduced into the reaction section 2 maintains an ionic state. Therefore, as the gas introduction section 3, the state of the gas G when introduced into the anode side (first cell 21a) of the reaction section 2 may be either a gas or a liquid, but preferably, it should be in the state of an aqueous solution in which the gas G is mixed (dissolved) within the anode side (first cell 21a) of the reaction section 2 after introduction.

[0049] As the gas treatment apparatus 1A of the present embodiment, as the gas introduction section 3, in order to introduce the gas G into the anode side of the reaction section 2 in the state of an aqueous solution in which the gas G is mixed (dissolved), as shown in FIG. 1, a gas-liquid contact section 4 for bringing the gas G from the gas generation source into contact with the aqueous solution is provided in the front stage of the reaction section 2, and it is possible to connect the gas-liquid contact section 4 and the gas introduction section 3.

[0050] More specifically, as shown in FIG. 1, as the gas introduction section 3, a pipe 31 for transferring the gas G from the gas generation source to the gas-liquid contact section 4 and an inlet 22a of the gas-liquid contact section 4 and the reaction section 2 are connected, and it is possible to provide a water-permeable pipe 32 for introducing an aqueous solution (gas G mixture) in which the gas G is mixed (dissolved) into the anode side (first cell 21a) of the reaction section 2. Also, a flow rate adjustment mechanism such as a valve may be provided in the pipe 31 or the pipe 32 in the gas introduction section 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 reaction section 2 and control the mass transfer rate of hydrogen sulfide to the electrode 23a.

[0051] Also, as the gas-liquid contact section 4, as shown in FIG. 1, the gas G is introduced through the pipe 31, and the anode solution S A is introduced, and it is possible to supply the gas G mixture obtained by the gas-liquid contact treatment of the gas G and the aqueous solution to the pipe 32 side.

[0052] At this time, as the gas-liquid contact section 4, any device capable of mixing the gas G from the gas generation source and the aqueous solution (including the anode solution S A is acceptable, and there are no particular limitations on the shape and material. For example, as an example of the gas-liquid contact part 4, there is one that has a water tank in which an aqueous solution is stored, and gas G is introduced into this water tank through a pipe 31 so as to come into contact with the aqueous solution. At this time, as the aqueous solution stored in the water tank, the anode solution S introduced through the above-described pipe 27 A In addition, an alkali solution may be supplied from outside the system, and a treatment related to so-called wet desulfurization may be used in combination. More specifically, as shown in FIG. 1, the gas-liquid contact part 4 has a tank in which a filler 41 is accommodated. While introducing gas G into the tank from below through a pipe 31, the anode solution S A is introduced through a pipe 27 from above the tank, and there is an example in which means (not shown) for supplying an aqueous solution (particularly an alkali solution) from outside the system is provided. At this time, as the internal structure of the tank in the gas-liquid contact part 4, a structure known as a gas scrubber can be used. Further, the filler 41 may be any material that can enhance the contact efficiency between the gas G and the aqueous solution, and known porous materials or adsorbents can be used.

[0053] After the gas-liquid contact treatment in the gas-liquid contact part 4, the gas G mixture obtained by the gas-liquid contact treatment of the gas G and the aqueous solution (anode solution S A ) is introduced into the reaction part 2 through a pipe 32. On the other hand, after the gas-liquid contact treatment, the gas G2 discharged from the gas-liquid contact part 4 contains, in addition to the gas components insoluble in water contained in the gas G, the products and unreacted substances resulting from the electrode reaction in the anode solution S A introduced into the gas-liquid contact part 4 that are discharged as gases, and this gas G2 is discharged to the outside of the system through a pipe 42.

[0054] The gas treatment device 1A in this embodiment uses hydrogen sulfide in the gas as an electron donor and performs power generation treatment or electrolysis treatment by 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 location where the electrochemical reaction occurs (reaction part 2). Therefore, it is preferable that the gas treatment device 1A in this embodiment insulates the locations other than the location where the electrochemical reaction occurs (reaction part 2). Specific examples of the insulation treatment include, for example, installing facilities other than the reaction part 2 (such as the gas introduction part 3 and the gas-liquid contact part 4) on top of an insulator, configuring the outer wall or inner wall of the gas introduction part 3 with an insulator, or coating the outer wall or inner wall of the gas introduction part 3 with an insulating material. Also, as the insulation treatment for each pipe connected to the reaction part 2, examples include making each pipe made of an insulator or coating each pipe with an insulating material.

[0055] In the gas treatment device 1A in the above-described embodiment, power generation treatment or electrolysis treatment can be performed by an electrode reaction using hydrogen sulfide in the gas G as an electron donor. Hereinafter, the reactions (treatment steps) related to the power generation treatment and electrolysis treatment in the gas treatment device 1A will be described in detail. Note that the following description shows an example of the power generation treatment and electrolysis treatment in this embodiment and is not limited thereto. Also, the following description describes the reactions (treatment steps) related to the reaction part 2, and the descriptions of the reactions (treatment steps) related to other configurations (such as the gas introduction part 3 and the gas-liquid contact part 4) are 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 and treatment steps.

[0056] (Reactions (treatment steps) related to the power generation treatment and electrolysis treatment in the gas treatment device) First, among the treatments in the gas treatment device 1A according to the first embodiment of the present invention, the reaction (treatment step) related to the power generation treatment will be described. The power generation process in the reaction section 2 of the gas treatment apparatus 1A according to this embodiment refers to a process in which the recovery of electrical energy and the removal of hydrogen sulfide (desulfurization) proceed simultaneously. Also, the reaction (treatment process) related to the power generation process in the gas treatment apparatus 1A according to this embodiment will be described for a process that uses hydrogen sulfide in the gas G as an electron donor and air (oxygen) as an electron acceptor.

[0057] For example, when performing the power generation process in the reaction section 2 shown in FIG. 1, the gas G (gas G mixture) is introduced into the first cell 21a, which is the anode side in the reaction section 2, from the gas generation source through the gas introduction section 3 (and the gas-liquid contact section 4) (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

[0058] Also, in the first cell 21a, a part of the hydrogen sulfide reacts as hydrogen sulfide ions. The reaction at this time is represented by the following reaction formula (formula 2).

Number

[0059] As shown in formula 1 and formula 2, in reaction R1, hydrogen sulfide donates electrons to the electrode 23a, and at the same time, hydrogen sulfide itself is oxidized and detoxified and deodorized.

[0060] Based on the reaction formulas shown in formula 1 and formula 2, after the reaction R1 at the electrode 23a proceeds, 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).

[0061] On one hand, air (oxygen) is introduced as an electron acceptor into the second cell 21b from the electron acceptor supply port 24a (step S2). Here, by reaction R2, the electrons that have moved from electrode 23a to electrode 23b are received by the electron acceptor via electrode 23b. Also, at this time, by reaction R3, the hydrogen ions that have moved to the second cell 21b side via the ion exchanger 25 also react with the electron acceptor (oxygen). The reaction at electrode 23b at this time (reaction R4) is represented by the following reaction formula (formula 3).

Number

[0062] Based on the above-described reactions R1 to R4 and steps S1 and S2, a current flows between electrode 23a and electrode 23b. As a result, the reaction using hydrogen sulfide in gas G as an electron donor proceeds, and the power generation process (electric energy recovery and desulfurization process) in the gas treatment apparatus 1A of the present embodiment is performed.

[0063] Then, as the power generation process based on the above-described reactions R1 to R4 and steps S1 and S2 proceeds, the gas G introduced into the reaction unit 2 becomes a gas (gas G1) in which hydrogen sulfide has been removed compared to when it was introduced, and is discharged outside the reaction unit 2 via the recovery port 22b and the pipe 26.

[0064] Therefore, by performing the power generation process in the reaction unit 2 of the gas treatment apparatus 1A of the present embodiment, power generation for recovering electric energy and desulfurization treatment and deodorization treatment become possible. In addition, even when the gas contains reducing substances (such as ammonia), which are harmful substances and odor substances other than hydrogen sulfide, they similarly function as electron donors, and through the progress of the reaction, detoxification and deodorization become possible.

[0065] Here, the electric energy obtained by the power generation process can be recovered and used through the external circuit C connected to electrodes 23a and 23b. At this time, in order to recover and use the electric energy, a power storage unit connected to each external circuit may be provided. 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 treatment device, or it may be used outside the gas treatment device. In particular, by using it as an energy source for driving the equipment (device operation) of the gas treatment device 1A, it is possible to provide the gas treatment device 1A in the present embodiment as a gas treatment device capable of energy saving, and in particular, it is possible to provide it as a gas treatment device capable of significantly reducing the running cost during continuous processing.

[0066] Next, among the processes in the gas treatment device 1A of the first embodiment of the present invention, the reaction (processing step) related to the electrolysis treatment will be described. The electrolysis treatment in the reaction unit 2 of the gas treatment device 1A of the present embodiment refers to the removal of hydrogen sulfide by voltage application (desulfurization by electrolysis) that progresses.

[0067] For example, when performing electrolysis treatment in the reaction unit 2 shown in FIG. 1, the gas G (gas G mixture) is introduced into the first cell 21a on the anode side in the reaction unit 2 from the gas generation source through the gas introduction unit 3 (and the gas-liquid contact unit 4) (step S3). Here, when a voltage is applied to the hydrogen sulfide dissolved in the aqueous solution in the first cell 21a through the external circuit C and the electrode 23a, the electrolysis of hydrogen sulfide progresses. At this time, the reaction (reaction R5) at the electrode 23a is represented by the following reaction formula (formula 4).

Number

[0068] In addition, in the first cell 21a, a part of the hydrogen sulfide reacts as hydrogen sulfide ions. The reaction at this time is represented by the following reaction formula (formula 5).

Number

[0069] As shown in formula 4 and formula 5, in reaction R5, hydrogen sulfide is rendered harmless and odorless by becoming sulfate ions.

[0070] Based on the reaction formulas shown in Equations 4 and 5, after reaction R5 at electrode 23a proceeds, the hydrogen ions generated by the reaction at electrode 23a migrate to the second cell 21b side via ion exchanger 25 (reaction R6).

[0071] Meanwhile, air (oxygen) is introduced as an electron acceptor into the second cell 21b through the electron acceptor supply port 24a (step S4). Here, the hydrogen ions that have migrated to the second cell 21b side via the ion exchanger 25 react with the electron acceptor (oxygen) through reaction R6. The reaction at electrode 23b at this time (reaction R7) proceeds according to the same reaction formula as formula 3 above.

[0072] Based on the above-described reactions R5 to R7 and steps S3 and S4, an electrolysis reaction proceeds in which hydrogen sulfide in the gas G becomes sulfate ions, and electrolysis (desulfurization) is carried out in the gas treatment device 1A of this embodiment.

[0073] As the electrolytic process proceeds through the above-mentioned reactions R5 to R7 and steps S3 and S4, the gas G introduced into the reaction section 2 becomes a gas (gas G1) in which hydrogen sulfide has been removed compared to when it was introduced, and is discharged outside the reaction section 2 via the recovery port 22b and the pipe 26. The reaction rate (reaction efficiency) of the electrolysis process can be adjusted by the applied voltage, so it is easier to increase the efficiency of hydrogen sulfide removal (desulfurization efficiency) with the electrolysis process than with the power generation process.

[0074] As described above, in the gas treatment device 1A of this embodiment, hydrogen sulfide in the gas G is removed by an electrode reaction in the reaction section 2, but this electrode reaction is preferably carried out in a state where hydrogen sulfide is dissolved in an aqueous solution (particularly hydrogen sulfide ions). Here, the various forms of hydrogen sulfide dissolved in water (H2S, HS - , S 2- The abundance ratio of HS can be calculated from the dissociation constant of hydrogen sulfide. The abundance ratio of HS increases on the neutral to acidic side, and on the alkaline side above pH 8.- It is known that it exists in more than 90%. In other words, in the region where the pH is neutral or lower, H2S may vaporize and be released from the dissolved state in the aqueous solution. Therefore, in order to increase the efficiency of the electrode reaction in the reaction section 2 and appropriately operate the gas treatment device, it is necessary to continuously acquire (monitor) information regarding the pH fluctuation on the anode side of the reaction section 2 (pH fluctuation of the electrolyte on the anode side).

[0075] In the acquisition of information on pH fluctuation in an arbitrary solution, generally a pH meter is used. However, hydrogen sulfide is a substance with high corrosiveness, and for continuously acquiring information on a solution containing hydrogen sulfide, the replacement frequency of the pH meter becomes high, resulting in increased costs. On the other hand, the inventor of the present invention has found that the hydrogen sulfide gas concentration in the gas G2 discharged from the gas-liquid contact section 4 into which the electrolyte (anode solution S A ) after the electrode reaction in the reaction section 2 is introduced is related to the component fluctuation in the electrolyte of the reaction section 2 (particularly the electrolyte on the anode side). More specifically, it has been found that the hydrogen sulfide gas concentration in the gas G2 discharged from the gas-liquid contact section 4 is related to the amount of hydrogen sulfide discharged without undergoing an electrode reaction in the reaction section 2, and further related to the component fluctuation in the electrolyte of the reaction section 2.

[0076] Based on this finding, in the gas treatment device 1A of the present embodiment, by measuring the hydrogen sulfide gas concentration in the gas G2 discharged from the gas-liquid contact section 4 and detecting the component fluctuation in the electrolyte based on the measured hydrogen sulfide gas concentration, monitoring related to gas treatment without using a pH meter is made possible. More specifically, examples of the gas treatment device 1A of the present embodiment include those equipped with a gas concentration measurement section 5 and a fluctuation detection section 6.[[ID=IS]]

[0077] The gas concentration measurement section 5 is for measuring the hydrogen sulfide gas concentration in the gas G2 discharged from the gas-liquid contact section 4. More specifically, the gas concentration measurement unit 5 may be provided with a known hydrogen sulfide meter on the pipe 42 that discharges the gas G2 from the gas-liquid contact unit 4. Here, the hydrogen sulfide meter is not particularly limited, and examples include a constant potential electrolytic hydrogen sulfide sensor and the like. The gas concentration measurement unit 5 of the present embodiment measures a gas containing hydrogen sulfide. Therefore, compared with a device that measures an aqueous solution containing hydrogen sulfide, the influence of corrosion is less, and continuous measurement can be performed at low cost.

[0078] The fluctuation detection unit 6 is for detecting fluctuations in the components in the electrolytic solution in the reaction unit 2 based on the hydrogen sulfide gas concentration measured by the gas concentration measurement unit 5. More specifically, the fluctuation detection unit 6 is provided based on the finding of the present inventor that the hydrogen sulfide gas concentration measured by the gas concentration measurement unit 5 is related to the amount of hydrogen sulfide discharged without undergoing an electrode reaction in the reaction unit 2, and further related to fluctuations in the components in the electrolytic solution (especially the electrolytic solution on the anode side) of the reaction unit 2. It enables the acquisition (monitoring) of information related to gas treatment efficiency.

[0079] The component fluctuations in the electrolytic solution to be detected by the fluctuation detection unit 6 are not particularly limited as long as they can be detected (or inferred) from the measurement result (hydrogen sulfide gas concentration in the gas G2) of the gas concentration measurement unit 5, but those related to the electrode reaction efficiency in the reaction unit 2, that is, those related to gas treatment efficiency, are preferred.

[0080] For example, as described above, the hydrogen sulfide gas concentration measured by the gas concentration measurement unit 5 is related to the amount of hydrogen sulfide discharged without undergoing an electrode reaction in the reaction unit 2. Here, the amount (concentration) of hydrogen sulfide discharged without undergoing an electrode reaction is greatly affected by fluctuations in the hydrogen sulfide ion concentration in the electrolytic solution and fluctuations in the hydrogen ion concentration in the electrolytic solution, that is, pH fluctuations. More specifically, when the hydrogen sulfide ion concentration in the electrolytic solution increases rapidly and a sufficient electrode reaction cannot proceed under predetermined reaction conditions (such as applied voltage) in the reaction unit 2, the anode solution S AThe amount of hydrogen sulfide remaining in it increases. Also, when pH fluctuations occur in the electrolytic solution and it becomes more acidic, much of the hydrogen sulfide in the electrolytic solution becomes in the form of H2S, resulting in a decrease in the electrode reaction efficiency or a vaporized state. That is, the anode solution S A The amount of hydrogen sulfide remaining in it increases. And the anode solution S A If the amount of hydrogen sulfide remaining in the anode solution S increases, the concentration of hydrogen sulfide gas contained in the gas G2 will naturally increase.

[0081] Also, the hydrogen sulfide gas concentration measured by the gas concentration measuring unit 5 is also related to the amount (concentration) of hydrogen sulfide discharged when sufficient capture (adsorption) does not occur in the gas-liquid contact part 4. When subjecting hydrogen sulfide to gas-liquid contact treatment, it is known that this gas capture efficiency (adsorption efficiency) depends on the pH of the aqueous solution brought into contact with the gas. Here, in the gas-liquid contact part 4 in the present embodiment, since the electrolytic solution (anode solution S A ) is used as the aqueous solution, the gas capture efficiency (adsorption efficiency) is affected by fluctuations in the hydrogen ion concentration in the electrolytic solution, that is, pH fluctuations. More specifically, when pH fluctuations occur in the electrolytic solution and it becomes more acidic, the gas capture efficiency in the gas-liquid contact part 4 will decrease, and the concentration of hydrogen sulfide gas contained in the gas G2 will increase.

[0082] Therefore, the fluctuation detection unit 6 can detect component fluctuations in the electrolytic solution by grasping the increasing trend of the hydrogen sulfide gas concentration measured by the gas concentration measuring unit 5 (the increasing trend of the hydrogen sulfide gas concentration contained in the gas G2). At this time, by detecting fluctuations in the electrolytic solution detected by the fluctuation detection unit 6, particularly fluctuations related to the hydrogen ion concentration or hydrogen sulfide ion concentration in the electrolytic solution, it becomes possible to obtain (monitor) information that greatly affects the gas treatment efficiency. In particular, it becomes possible to obtain information related to pH fluctuations during gas treatment by means other than a pH meter.

[0083] The detection means by the fluctuation detection unit 6 is not particularly limited, but based on the measurement result of the gas concentration measurement unit 5, it is possible to grasp a sharp increase tendency of the hydrogen sulfide gas concentration in the gas G2, or to perform a comparison operation with a preset standard value (or upper limit threshold value). For example, when the electrode reaction in the reaction unit 2 is proceeding appropriately, the hydrogen sulfide gas concentration in the gas G2 is set as the standard value (C1). The standard value (C1) may be based on actual measurement, or may be a set value expected under the design and operating conditions of the gas treatment apparatus 1A. And in the fluctuation detection unit 6, detection can be performed by obtaining the difference between this standard value (C1) and the actual measurement value (C2) by the gas concentration measurement unit 5. Also, as another example of the detection means in the fluctuation detection unit 6, by obtaining the difference between the actual measurement values by the gas concentration measurement unit 5, it is possible to grasp a sharp increase tendency of the hydrogen sulfide gas concentration in the gas G2 and perform detection.

[0084] The fluctuation detection unit 6 may include, for example, calculations and operations by an operator, but preferably uses a computing device having a data input / output function for information acquisition and executing a program for performing calculations related to component fluctuations in the electrolytic solution by a processor such as a CPU. Thereby, it becomes possible to quickly and accurately detect component fluctuations in the electrolytic solution, that is, to perform monitoring related to gas treatment.

[0085] As described above, in the gas treatment apparatus 1A in the present embodiment, since a reaction using the component (hydrogen sulfide) in the gas G to be treated directly is performed, compared with dry desulfurization or wet desulfurization, it is possible to significantly reduce the cost related to chemicals (desulfurizing agents, etc.) supplied from outside the system. Also, generally, electrode reactions have a high reaction rate and much knowledge is known about the parameters related to the reaction conditions. Therefore, the control of the treatment conditions related to the electrode reaction can be easily performed compared with the control of the treatment conditions related to the treatment using microorganisms. Therefore, in the treatment of a gas containing hydrogen sulfide, it is possible to perform a desulfurization treatment at low cost and stably, and at the same time, it is possible to efficiently recover and utilize energy.

[0086] In addition, in the gas treatment apparatus 1A according to the present embodiment, in the reaction unit 2, 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 recover high-purity methane gas as the gas G1 (or gas G2).

[0087] And in the gas treatment apparatus 1A according to the present embodiment, the anode solution S discharged from the reaction unit 2 A is introduced into the gas-liquid contact unit 4, and the hydrogen sulfide gas concentration contained in the gas G2 discharged therefrom is measured. Then, by detecting the component variation in the electrolytic solution from the measured hydrogen sulfide gas concentration, monitoring related to gas treatment without relying on a pH meter becomes possible. That is, the gas treatment apparatus 1A according to the present embodiment enables continuous monitoring related to gas treatment simply without increasing costs when performing efficient gas treatment. In addition, in the gas treatment apparatus 1A according to the present embodiment, by detecting the variation in the components in the electrolytic solution detected by the variation detection unit 6, particularly the variation related to the hydrogen ion concentration or hydrogen sulfide ion concentration in the electrolytic solution, it becomes possible to obtain (monitor) information that greatly affects the gas treatment efficiency. In particular, it becomes possible to obtain information related to pH variation during gas treatment by simple means other than a pH meter. More specifically, the gas treatment apparatus 1A according to the present embodiment measures the hydrogen sulfide gas concentration contained in the gas G2 discharged from the gas-liquid contact unit 4 instead of measuring the pH of the solution (electrolytic solution, aqueous solution of the gas-liquid contact unit 4, etc.) in the system by a pH meter, thereby making it possible to grasp the pH variation in the gas treatment process in the gas treatment apparatus 1A. As a result, in the gas treatment apparatus 1A according to the present embodiment, it is possible to improve the monitoring accuracy without increasing the cost required for continuous monitoring necessary for performing efficient gas treatment.

[0088] 〔Second Embodiment〕 FIG. 2 is a schematic explanatory diagram showing a gas treatment apparatus according to the second embodiment of the present invention. The gas treatment apparatus 1B according to the second embodiment includes a pH adjustment unit 7 that adjusts the pH of the electrolytic solution based on the detection result of the fluctuation detection unit 6, with respect to the gas treatment apparatus 1A of the first embodiment. Here, the double-headed dashed line in FIG. 2 indicates that they are controllably connected. Note that the description of the components that are the same as those in the first embodiment will be omitted.

[0089] In the gas treatment apparatus 1B of the present embodiment, as one of the countermeasures when it is grasped that the electrode reaction efficiency tends to decrease due to the component fluctuation in the electrolytic solution S A detected by the fluctuation detection unit 6, the pH of the electrolytic solution is adjusted. As described above, when fluctuations in the components in the electrolytic solution occur, that is, fluctuations in the hydrogen ion concentration, i.e., pH fluctuations, it has a great impact on the electrode reaction efficiency in the reaction unit 2. In particular, when the pH of the electrolytic solution becomes more acidic, the abundance ratio of H2S in the form of hydrogen sulfide increases, resulting in a decrease in the electrode reaction efficiency and the vaporization of hydrogen sulfide. Also, as described above, the pH fluctuation of the electrolytic solution also affects the gas capture efficiency in the gas-liquid contact unit 4. Therefore, in order to maintain and improve the gas treatment efficiency and continue the proper operation of the gas treatment apparatus, it is necessary to adjust the pH of the electrolytic solution to be more alkaline.

[0090] The pH adjustment unit 7 of the present embodiment only needs to be such that the detection result of the fluctuation detection unit 6 is input and the pH of the electrolytic solution can be adjusted according to the detection result of the fluctuation detection unit 6, and the specific configuration and structure are not particularly limited. Note that the timing of the operation of the pH adjustment unit 7 may be the timing when the fluctuation detection unit 6 detects the component fluctuation of the electrolytic solution based on the increase in the hydrogen sulfide gas concentration in the gas G2. In other words, the timing of the operation of the pH adjustment unit 7 may be the timing according to the measurement result of the hydrogen sulfide gas concentration measured by the gas concentration measurement unit 5. For example, as the pH adjustment unit 7, there is provided a pH adjuster addition means for adding a pH adjuster (alkali agent) to the gas-liquid contact unit 4 or the anode side of the reaction unit 2, and this pH adjuster addition means is operated according to the detection result of the fluctuation detection unit 6.

[0091] Also, as another example of the pH adjuster 7, as shown in FIG. 2, a pipe 71 connecting the electron acceptor discharge port 24b on the cathode side of the reaction unit 2 and the gas-liquid contact unit 4, and a flow rate adjustment mechanism 72 (such as a valve) provided on the pipe 71 and capable of opening and closing control based on the detection result of the fluctuation detection unit 6 are provided, and the cathode solution S C (the electrolytic solution on the cathode side after the electrode reaction) is supplied to the gas-liquid contact unit 4.

[0092] As described above, on the cathode side (the second cell 21b) of the reaction unit 2, oxygen functions as an electron acceptor and the reaction based on Formula 3 proceeds. At this time, when water and oxygen are present in the second cell 21b, the reaction based on the following reaction formula (Formula 6) proceeds.

Equation

[0093] As shown in Formula 6, in the presence of oxygen (air) and water, on the cathode side (the second cell 21b) of the reaction unit 2, the cathode solution S C forms an aqueous solution containing hydroxide ions. That is, the cathode solution S C functions as an alkaline pH adjuster.

[0094] Therefore, as shown in FIG. 2, by introducing the cathode solution S C to the electrolytic solution side (the gas-liquid contact unit 4 or the anode side of the reaction unit 2) via the pipe 71 and the flow rate adjustment mechanism 72, the pH of the electrolytic solution can be adjusted. Thereby, it is not necessary to supply a pH adjuster from outside the system, and it is possible to reduce the cost related to pH adjustment. In addition, in order to more reliably perform the pH adjustment to a predetermined pH value, as the pH adjuster 7, in addition to the means using the cathode solution S C , a means for separately adding a pH adjuster may be provided. Even in this case, it is possible to reduce the usage amount of the pH adjuster supplied from outside the system.

[0095] As described above, in the gas treatment apparatus 1B of the present embodiment, while achieving various effects described in the gas treatment apparatus 1A, by providing a pH adjustment unit, it is possible to optimize the pH, which is one factor affecting the gas treatment efficiency, based on the detection result of the fluctuation detection unit, that is, the result of monitoring related to gas treatment. As a result, it becomes easy to continuously perform efficient gas treatment in conjunction with the monitoring related to gas treatment.

[0096] 〔Third Embodiment〕 FIG. 3 is a schematic explanatory diagram showing a gas treatment apparatus according to the third embodiment of the present invention. The gas treatment apparatus 1C according to the third embodiment includes an abnormality determination unit 8 that determines the presence or absence of an operation abnormality based on the detection result of the fluctuation detection unit 6 with respect to the gas treatment apparatus 1A of the first embodiment. Note that the description of the same configuration as that of the first embodiment is omitted.

[0097] The gas treatment apparatus 1C in the present embodiment is provided with an abnormality determination unit 8 as a means for grasping that a situation to be dealt with regarding the apparatus operation has occurred from the component fluctuation in the electrolytic solution, which is the result detected by the fluctuation detection unit 6. As described above, factors causing component fluctuations in the electrolytic solution detected by the fluctuation detection unit 6 include cases where the concentration of hydrogen sulfide ions in the electrolytic solution increases rapidly and a sufficient electrode reaction cannot proceed under predetermined reaction conditions (such as applied voltage) in the reaction unit 2, or cases where the pH fluctuation in the electrolytic solution becomes acidic and most of the hydrogen sulfide in the electrolytic solution becomes in the form of H2S, resulting in a decrease in the electrode reaction efficiency and vaporization of hydrogen sulfide. That is, the component fluctuation in the electrolytic solution detected by the fluctuation detection unit 6 based on the measurement result measured by the gas concentration measurement unit 5 also serves as an indicator indicating deviation from the situation and processing conditions for continuing appropriate apparatus operation.

[0098] When the detection result of the fluctuation detection unit 6 is input to the abnormality determination unit 8 in this embodiment, the abnormality determination unit 8 can determine whether or not a situation that should be addressed regarding the operation of the gas treatment device 1C has occurred according to the detection result of the fluctuation detection unit 6. In other words, the abnormality determination unit 8 in this embodiment can determine whether or not a situation that should be addressed regarding the operation of the gas treatment device 1C has occurred according to the measurement result of the hydrogen sulfide gas concentration measured by the gas concentration measurement unit 5, and the specific configuration and structure are not particularly limited.

[0099] As the abnormality determination unit 8 in this embodiment, for example, in relation to the detection means by the fluctuation detection unit 6, it is possible to perform a comparison operation between the detection result of the fluctuation detection unit 6 and a preset threshold value or upper limit fluctuation range. More specifically, when the result detected by the fluctuation detection unit 6 (such as a sudden upward trend or increase in the hydrogen sulfide gas concentration in the gas G2) exceeds a preset threshold value or upper limit fluctuation range, it indicates that a situation that should be addressed regarding the operation of the gas treatment device 1C has occurred, such as the electrode reaction in the reaction unit 2 not proceeding properly due to the vaporization of hydrogen sulfide or a sudden increase in hydrogen sulfide in the gas G, that is, it is determined that there is an operation abnormality.

[0100] Similar to the fluctuation detection unit 6, the abnormality determination unit 8 may include, for example, calculations and operations by an operator. However, it is preferable to use a computing device that has a data input / output function for information acquisition and executes a program for performing calculations related to determining the presence or absence of operation abnormality based on the detection result of the fluctuation detection unit 6 by a processor such as a CPU. This makes it possible to quickly and accurately make a determination for appropriately continuing efficient gas treatment in conjunction with the monitoring related to gas treatment.

[0101] In addition, it is preferable to provide the abnormality determination unit 8 with countermeasure means for taking necessary countermeasures after it is determined that there is an operation abnormality. For example, as shown in FIG. 3, the abnormality determination unit 8 and the external circuit C of the reaction unit 2 are controllably connected, and after it is determined by the abnormality determination unit 8 that there is an operation abnormality, it is possible to stop the operation of the external circuit C. As another example, a flow rate adjustment mechanism (valve) is provided on the pipe 31, and after the abnormality determination unit 8 determines that there is an operation abnormality, this flow rate adjustment mechanism is closed to stop the supply of the gas G to the gas treatment device 1C. As another example, an alarm that operates when the abnormality determination unit 8 determines that there is an operation abnormality may be provided. Note that the type of the alarm is not particularly limited, and a known alarm notified by sound, light, characters, etc. can be used. Furthermore, the gas treatment device 1C of the present embodiment is provided with the pH adjustment unit 7 in the second gas treatment device 1B described above, and after the abnormality determination unit 8 determines that there is an operation abnormality, the pH adjustment unit 7 is operated to adjust the pH of the electrolytic solution. It is preferable to provide at least one of these countermeasures, and a plurality of them may be combined. This makes it easy to appropriately perform the necessary countermeasures for efficiently continuing the gas treatment in conjunction with the monitoring related to the gas treatment.

[0102] Furthermore, it is preferable that the abnormality determination unit 8 of the present embodiment determines the presence or absence of an operation abnormality based on the result of the electrode reaction in the reaction unit 2 in addition to the detection result of the fluctuation detection unit 6. When a situation that needs to be addressed occurs during the operation of the gas treatment device 1C, the cause may be due to factors other than the component fluctuations in the electrolytic solution, and may also be due to the electrode 23a, 23b (or the external circuit C) side of the reaction unit 2. More specifically, for example, when the electrode reaction in the reaction unit 2 does not proceed appropriately due to an abnormality in the external circuit C or the electrodes 23a, 23b, it is difficult to appropriately grasp only the content detected by the fluctuation detection unit 6. On the other hand, as shown in FIG. 3, the abnormality determination unit 8 is input with the results of the electrode reaction in the reaction unit 2, that is, the current value generated by the power generation process and the value of the applied voltage related to the electrolysis process. Based on this value, the presence or absence of abnormalities in the external circuit C and the electrodes 23a and 23b in the reaction unit 2 is determined together, so that it is possible to grasp whether the operation abnormality of the gas treatment device 1C is caused by component fluctuations in the electrolytic solution or by the electrode side of the reaction unit 2. As a result, it becomes even easier to quickly and accurately take measures to appropriately continue efficient gas treatment in conjunction with the monitoring related to gas treatment.

[0103] As described above, in the gas treatment device 1C of the present embodiment, while achieving various effects described in the gas treatment device 1A, by providing an abnormality determination unit, it becomes possible to grasp that a situation requiring action regarding the operation of the gas treatment device has occurred based on the detection result of the fluctuation detection unit, that is, the result of the monitoring related to gas treatment. As a result, it becomes easy to make judgments and take measures to appropriately continue efficient gas treatment in conjunction with the monitoring related to gas treatment.

[0104] Note that the above-described embodiment shows an example of a gas treatment device and a gas treatment method. The gas treatment device and the gas treatment method according to the present invention are not limited to the above-described embodiment, and the gas treatment device and the gas treatment method according to the above-described embodiment may be modified without changing the gist described in the claims.

[0105] For example, the gas treatment device in the present embodiment may be provided with means for preventing the adhesion and deposition of microorganisms on each electrode (electrodes 23a, 23b). Examples of such means include coating the electrode surface with a material that prevents the adhesion of microorganisms, and making the structure of the electrode itself have a shape that makes it difficult for microorganisms to adhere. As a result, even when microorganisms flow into the reaction unit 2, it is possible to suppress the inhibition of the electrode reaction by the microorganisms.

[0106] Alternatively, for example, the gas treatment apparatus in the present embodiment may omit some structures to further simplify the apparatus configuration. Examples of the omissible structure include, for example, the ion exchanger 25. This enables simplification of the reaction section 2 and facilitates maintenance work. Another example of the omissible structure includes the electron acceptor supply port 24a and the electron acceptor discharge port 24b in the second cell 21b in the reaction section 2. This makes it possible to further simplify the reaction section 2. At this time, for example, a structure may be adopted in which one surface of the electrode 23b contacts the aqueous solution or the ion exchanger 25 in the first cell 21a, and the other surface is in direct contact with the outside air (air) as a whole. Further, it is preferable to provide a breathable material that is easy to exchange or wash on the surface of the electrode 23b on the outside air side. This can suppress the adhesion of solid impurities such as dust to the surface of the electrode 23b.

[0107] Also, for example, although the gas treatment apparatus in the present embodiment shows a configuration in which the gas-liquid contact section 4 and the gas introduction section 3 are connected, it is not limited thereto. For example, as the gas introduction section 3, a pipe is provided to directly connect the gas generation source and the inlet 22a provided in the first cell 21a of the reaction section 2, and an aqueous solution is supplied to the first cell 21a in advance. Thus, the gas G introduced in a gaseous state through the gas introduction section 3 can contact the aqueous solution in the first cell 21a, and the reaction can proceed with hydrogen sulfide in the gas G dissolved in the aqueous solution. On the other hand, at this time, as the gas-liquid contact section 4, the electrolytic solution S A is introduced through the pipe 27 of the reaction section 2, and a gas (other than the gas G) to be treated by the gas-liquid contact treatment is introduced. For example, when the gas G is biogas, the gas G1 discharged from the reaction section 2 may be introduced into the gas-liquid contact section 4 to further purify the methane gas in the gas G1. Also in this case, as in the above-described embodiment, by performing detection by the fluctuation detection section 6 using the measurement result by the gas concentration measurement section 5, it is possible to continuously perform monitoring related to gas treatment at low cost and simply.

[0108] Furthermore, in addition to being used independently, the configuration of the gas treatment apparatus according to the present embodiment may be used to construct a treatment system in combination with other treatment facilities. Furthermore, it may be applied as a gas treatment apparatus in an existing treatment system. As a result, a treatment system including the gas treatment apparatus of the present invention having functions of power generation treatment and electrolysis treatment 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

[0109] The gas treatment apparatus and gas treatment method of the present invention are used for treating gases 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, wastewater / 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.

Explanation of Signs

[0110] 1A, 1B, 1C Gas treatment apparatus, 2 Reaction section, 21a First cell, 21b Second cell, 22a Inlet, 22b, 22c Recovery ports, 23a, 23b Electrodes, 24a Electron acceptor supply port, 24b Electron acceptor discharge port, 25 Ion exchanger, 26, 27 Pipes, 3 Gas introduction section, 31, 32 Pipes, 4 Gas-liquid contact section, 41 Packing material, 42 Pipe, 5 Gas concentration measurement section, 6 Fluctuation detection section, 7 pH adjustment section, 71 Pipe, 72 Flow adjustment mechanism, 8 Abnormality determination section, C External circuit, G Gas containing hydrogen sulfide, G1 Gas from which hydrogen sulfide has been removed in the reaction section, G2 Gas discharged from the gas-liquid contact section, S A Anode solution (electrolyte on the anode side after the electrode reaction), S C Cathode solution (electrolyte on the cathode side after the electrode reaction)

Claims

1. A gas treatment apparatus for treating a gas containing hydrogen sulfide, comprising: a reaction section having a pair of electrodes; a gas introduction section for introducing a gas containing hydrogen sulfide to the anode side of the reaction section; a gas-liquid contact section into which the anode solution discharged from the reaction section is introduced; a gas concentration measurement section for measuring the hydrogen sulfide gas concentration discharged from the gas-liquid contact section; and a variation detection section for detecting a change in the components in the electrolytic solution in the reaction section based on the hydrogen sulfide gas concentration measured by the gas concentration measurement section.

2. The gas treatment apparatus according to claim 1, wherein the variation detection section detects a variation related to the hydrogen ion concentration or the hydrogen sulfide ion concentration in the electrolytic solution.

3. The gas treatment apparatus according to claim 1 or 2, further comprising a pH adjustment section for adjusting the pH of the electrolytic solution based on the detection result of the variation detection section.

4. The gas treatment apparatus according to claim 1 or 2, further comprising an abnormality determination section for determining the presence or absence of an abnormal operation based on the detection result of the variation detection section.

5. The gas treatment apparatus according to claim 4, wherein the abnormality determination section determines the presence or absence of an abnormal operation based on the detection result of the variation detection section and the result of the electrode reaction in the reaction section.

6. A gas treatment method for treating a gas containing hydrogen sulfide, comprising: a gas introduction step of introducing a gas containing hydrogen sulfide to the anode side of a reaction section having a pair of electrodes; a reaction step of performing an electrode reaction in the reaction section; a gas-liquid contact step of introducing the anode solution discharged from the reaction section; a gas concentration measurement step of measuring the hydrogen sulfide gas concentration discharged from the gas-liquid contact step; and a variation detection step of detecting a change in the components in the electrolytic solution in the reaction step based on the hydrogen sulfide gas concentration measured in the gas concentration measurement step.

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