Biogas-based electrochemical hydrogen extraction and separation system

Abstract

The present invention relates to a biogas-based electrochemical hydrogen extraction and separation system comprising a solid oxide fuel cell and a solid oxide water electrolysis cell, and a method for operating same. Specifically, the biogas-based electrochemical hydrogen extraction and separation system comprising a solid oxide fuel cell and a solid oxide water electrolysis cell is characterized by comprising: a fuel supply part for supplying biogas as fuel; a first reaction part for reforming the biogas supplied through the fuel supply part so as to generate a first reformed gas; a second reaction part for secondarily reforming the first reformed gas so as to generate a second reformed gas; a third reaction part for receiving the second reformed gas generated in the second reaction part and generating electricity; a fourth reaction part for receiving unreacted gas generated in the third reaction part and using the unreacted gas as fuel, and receiving steam generated in the third reaction part and generating hydrogen; and a power converter which receives the electricity generated in the third reaction part and supplies the electricity to the first reaction part and the fourth reaction part.

Description

Biogas-based electrochemical hydrogen extraction and separation system

[0001] The present invention relates to a biogas-based electrochemical hydrogen extraction and separation system.

[0002] Specifically, it relates to a biogas-based electrochemical hydrogen extraction and separation system that plasma-catalytically reforms biogas and uses it to operate a solid oxide fuel cell and a solid oxide water electrolysis cell.

[0003] Recently, as concerns about the depletion of existing energy resources such as oil and natural gas have grown and demand for eco-friendly resources has increased, research on fuel cells is actively being conducted as a new alternative energy source.

[0004] A fuel cell is an eco-friendly energy source that utilizes the reverse reaction of water electrolysis. Various types of fuel cells are being developed, one of which is the solid oxide fuel cell (SOFE).

[0005] A solid oxide fuel cell system includes a solid oxide that acts as an electrolyte, a fuel electrode to which hydrogen gas as a fuel is supplied, and an air electrode to which air is supplied. Oxygen ions generated by a reduction reaction of oxygen at the air electrode move to the fuel electrode through the electrolyte and react with hydrogen supplied to the fuel electrode to produce water and electricity.

[0006] In general, solid oxide fuel cell systems operate at high temperatures of 500 to 800°C, so they have higher electrical efficiency than other fuel cells, are free from poisoning by carbon monoxide and other gases, and have the advantages of no electrolyte loss, replenishment, or corrosion.

[0007] At this time, to use a solid oxide fuel cell system, a stationary solid oxide fuel cell must be heated to its operating temperature. Conventionally, a separate external burner was installed to heat the fuel cell to operating temperature, and this burner was used to heat the fuel cell to operating temperature. However, this heating method has the following problems: it takes a very long time to heat the solid oxide fuel cell to operating temperature, localized high temperatures can damage individual cells, and the uneven heat distribution makes rapid operation difficult.

[0008] Meanwhile, fuel cell technology is a promising technology with high efficiency and economic feasibility, but its smooth use requires the establishment of a system for hydrogen production and supply, so it can be considered in conjunction with hydrogen production.

[0009] The solid oxide electrolysis cell (SOEC), one of the hydrogen production technologies, is an electrolysis device that uses solid oxide as an electrolyte and consists of an air electrode, a solid oxide electrolyte layer, and a fuel electrode. In the case of the conventional solid oxide electrolysis cell, oxygen ions are conducted through the solid oxide electrolyte layer, so the reactant (H2O) and product (H2) exist together in the fuel electrode, so a hydrogen extraction process is essential. In addition, since unreacted gas carbon dioxide exists in the fuel electrode, an additional pressure swing adsorption (PSA) separation process is required, which has the problem of reducing the overall efficiency.

[0010] In order to solve the above problems, the present invention aims to provide a biogas-based electrochemical hydrogen extraction separation system.

[0011] Specifically, the purpose is to provide a biogas-based electrochemical hydrogen extraction and separation system that supplies biogas heated and reformed by plasma as fuel for a solid oxide fuel cell to generate water and electricity, and electrolyzes the generated water to produce hydrogen.

[0012] In addition, the purpose is to provide a biogas-based electrochemical hydrogen extraction and separation system that can maintain long-term stability by reducing carbon deposition on a solid oxide fuel cell anode through direct reforming of biogas.

[0013] The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0014] According to one aspect of the present invention for achieving the above object, a biogas-based electrochemical hydrogen extraction and separation system including a solid oxide fuel cell and a solid oxide water electrolysis cell is provided, the system including a fuel supply unit for supplying biogas as fuel, a first reaction unit for reforming the biogas supplied through the fuel supply unit to produce a first reformed gas, a second reaction unit for secondarily reforming the first reformed gas to produce a second reformed gas, a third reaction unit for receiving the second reformed gas generated in the second reaction unit to produce electricity, a fourth reaction unit for receiving unreacted gas generated in the third reaction unit to use it as fuel and for receiving steam generated in the third reaction unit to produce hydrogen, and a power converter for receiving electricity generated in the third reaction unit to supply electricity to the first reaction unit and the fourth reaction unit.

[0015] Preferably, the first reaction unit further includes a first reactor that uses plasma as a reforming means, the first reactor reforming the biogas to produce a first reformed gas and a heat source, and the first reaction unit may be disposed below the second reaction unit.

[0016] Preferably, the first reformed gas includes methane, carbon dioxide, carbon monoxide, hydrogen, and steam, and the second reaction unit may receive the first reformed gas generated in the first reaction unit and reform it into a second reformed gas including hydrogen, carbon dioxide, and carbon monoxide.

[0017] Preferably, the second reaction section is configured to have a catalyst disposed therein to react with the first reformed gas, and the catalyst may include Ni-perovskite.

[0018] Preferably, the third reaction unit may include a first fuel electrode that receives the second reformed gas to generate electricity and water, wherein hydrogen in the second reformed gas is oxidized to generate electrons and hydrogen ions, a first air electrode that receives electrons from the first fuel electrode and reacts with external air to generate oxygen ions, a first solid electrolyte layer that receives oxygen ions from the first air electrode and supplies them to the first fuel electrode, and an air inlet portion through which air is introduced into an upper portion of the first air electrode, and an air outlet portion through which unreacted air is discharged.

[0019] Preferably, the fourth reaction unit may be configured to receive unreacted gas containing carbon monoxide and carbon dioxide, heat, and water from the third reaction unit to produce hydrogen, and may include a second cathode that uses the unreacted gas containing carbon monoxide and carbon dioxide as fuel and electrolyzes steam to separate it into cations, oxygen, and electrons, a second solid electrolyte layer that transfers cations from the second cathode to a second fuel electrode, a second fuel electrode that generates hydrogen by reacting cations and electrons transferred from the second cathode, and a hydrogen discharge unit that discharges hydrogen generated at the second fuel electrode to the outside.

[0020] Preferably, the second reaction section, the third reaction section, and the fourth reaction section may be preheated with the high-temperature heat generated in the first reaction section.

[0021] According to another aspect of the present invention for achieving the above-described object, a method for operating a biogas-based electrochemical hydrogen extraction and separation system is provided, comprising: a fuel supply step of supplying biogas as fuel; a first reforming step of reforming the biogas supplied through the fuel supply unit to produce a first reformed gas; a second reforming step of secondarily reforming the first reformed gas to produce a second reformed gas; an electricity generation step of receiving the second reformed gas produced in the second reforming step to generate electricity; and a hydrogen generation step of receiving unreacted gas produced in the electricity generation step to use it as fuel and receiving steam produced in the electricity generation step to produce hydrogen, wherein the electricity produced in the electricity generation step is supplied to the first reforming step and the hydrogen generation step.

[0022] Preferably, the first reforming step generates a first reformed gas by applying plasma as a reforming means, and the first reformed gas may include hydrogen, water, and unreacted gas (carbon monoxide, carbon dioxide).

[0023] Preferably, the second reforming step supplies the first reformed gas to a functional catalyst layer to generate a second reformed gas, and the second reformed gas may include hydrogen and unreacted gas (carbon monoxide, carbon dioxide).

[0024] Preferably, the electricity generation step may be configured to generate electricity and water by supplying a second reformed gas, wherein hydrogen in the second reformed gas is oxidized at the first fuel electrode to form electrons and hydrogen ions, the first air electrode receives electrons from the first fuel electrode and reacts with external air to generate oxygen ions, and the oxygen ions may be transferred from the first air electrode to the first fuel electrode through the first solid electrolyte layer, and the oxygen ions transferred to the first fuel electrode may react with the hydrogen ions to form water.

[0025] Preferably, the hydrogen generation step may be a step of producing hydrogen by supplying unreacted gas containing carbon monoxide and carbon dioxide formed in the electricity generation step, heat, and water, using the unreacted gas containing carbon monoxide and carbon dioxide as fuel at the second cathode, electrolyzing steam to separate it into cations, oxygen, and electrons, transferring the cations formed from the second cathode to the second fuel electrode through the second solid electrolyte layer, and generating hydrogen by reacting the cations and electrons transferred from the second cathode at the second fuel electrode.

[0026] The present invention has the effect of providing a biogas-based electrochemical hydrogen extraction separation system.

[0027] Specifically, the present invention provides a biogas-based electrochemical hydrogen extraction and separation system that supplies biogas heated and reformed by plasma as fuel for a solid oxide fuel cell to generate water and electricity, and electrolyzes the generated water to produce hydrogen.

[0028] Additionally, direct reforming of biogas has the effect of reducing carbon deposition on the fuel electrode of a solid oxide fuel cell, thereby maintaining long-term stability.

[0029] Additionally, by using biogas, a renewable resource, as fuel, it has the effect of increasing resource reuse and energy efficiency.

[0030] In addition, by operating reforming and solid oxide fuel cells and solid oxide water electrolysis cells using the high-temperature heat generated by plasma without using an external burner, it has the effect of reducing energy loss and increasing energy efficiency.

[0031] Further scope of the applicability of the present invention will become apparent from the detailed description below. However, since various modifications and variations within the spirit and scope of the present invention will become apparent to those skilled in the art, it should be understood that the detailed description and specific examples, such as preferred embodiments of the present invention, are given by way of example only.

[0032] FIG. 1 is a schematic diagram showing a biogas-based electrochemical hydrogen extraction separation system according to one embodiment of the present invention.

[0033] FIG. 2 is a schematic diagram of a biogas-based electrochemical hydrogen extraction separation system according to one embodiment of the present invention.

[0034] Figure 3 is a schematic diagram showing the temperature distribution of a biogas-based electrochemical hydrogen extraction separation system according to one embodiment of the present invention.

[0035] The purpose and technical configuration of the present invention and the resulting operation and effects will be more clearly understood through a detailed description based on the drawings attached to the specification of the present invention.

[0036] The terminology used herein is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. For example, references to a component in this specification as "including" or "comprising" do not exclude other components, unless specifically stated otherwise, but rather imply the inclusion of other components.

[0037]

[0038] The present invention relates to a biogas-based electrochemical hydrogen extraction separation system and its operating method.

[0039] Specifically, the present invention relates to a biogas-based electrochemical hydrogen extraction and separation system including a solid oxide fuel cell and a solid oxide water electrolysis cell, comprising: a fuel supply unit for supplying biogas as fuel; a first reaction unit for reforming the biogas supplied through the fuel supply unit to produce a first reformed gas; a second reaction unit for secondarily reforming the first reformed gas to produce a second reformed gas; a third reaction unit for receiving the second reformed gas generated in the second reaction unit to produce electricity; a fourth reaction unit for receiving unreacted gas generated in the third reaction unit to use it as fuel and for receiving steam generated in the third reaction unit to produce hydrogen; and a power converter for receiving electricity generated in the third reaction unit to supply electricity to the first reaction unit and the fourth reaction unit, wherein the biogas-based electrochemical hydrogen extraction and separation system plasma-catalytically reforms biogas and operates the solid oxide fuel cell and the solid oxide water electrolysis cell using the same. It is about a hydrogen extraction separation system.

[0040] In addition, the present invention relates to a method for operating a biogas-based electrochemical hydrogen extraction and separation system, comprising: a fuel supply step of supplying biogas as fuel; a first reforming step of reforming the biogas supplied through the fuel supply unit to produce a first reformed gas; a second reforming step of secondarily reforming the first reformed gas to produce a second reformed gas; an electricity generation step of receiving the second reformed gas produced in the second reforming step to produce electricity; and a hydrogen generation step of receiving unreacted gas produced in the electricity generation step to use it as fuel and receiving steam produced in the electricity generation step to produce hydrogen, wherein the electricity produced in the electricity generation step is supplied to the first reforming step and the hydrogen generation step.

[0041] Hereinafter, the present invention will be described in detail by describing preferred embodiments thereof with reference to the attached drawings. The embodiments described below are provided to facilitate the technical concept of the present invention for those skilled in the art to understand, and should not be construed as limiting the present invention. It should be understood that the embodiments of the present invention can have various applications to those skilled in the art.

[0042] FIG. 1 is a schematic diagram showing a biogas-based electrochemical hydrogen extraction separation system according to one embodiment of the present invention, and FIG. 2 is a configuration diagram of a biogas-based electrochemical hydrogen extraction separation system according to one embodiment of the present invention.

[0043] Referring to FIGS. 1 and 2, a biogas-based electrochemical hydrogen extraction separation system (100) can be configured to include a fuel supply unit (110), a first reaction unit (200), a second reaction unit (300), a third reaction unit (400), a fourth reaction unit, and a power converter (600).

[0044] The fuel supply unit (110) is arranged on the side of the first reaction unit (200) and can supply fuel to the first reaction unit (200). The fuel can supply fuel containing hydrogen, such as alcohol fuel, hydrocarbon fuel, natural gas fuel, and biogas, and more specifically, it is preferable to supply biogas containing methane (CH4) and carbon dioxide (CO2).

[0045] The first reaction unit (200) above is a reforming device that reforms fuel supplied from the fuel supply unit (110) to generate primary reformed gas and a heat source. The primary reformed gas includes hydrogen, carbon dioxide, carbon monoxide, etc., and may include unreacted gas (methane, CH4) that has not been reacted.

[0046] At this time, plasma is used as a reforming means to reform the fuel and generate reformed gas. The first reaction unit (200) may be a plasma reactor, and the reforming means may be arc plasma. In addition, the fuel is heated as it is reformed using plasma as a reforming means, and the temperature of the reformed gas may be 500 to 900°C.

[0047] In addition, the first reactor (200) is placed below the second reaction unit (300) described below. It is preferable that the reformed gas including the unreacted gas generated through reforming of the fuel in the first reaction unit (200) and the high-temperature heat generated by the reaction preheat the second reaction unit (300), the third reaction unit (400), and the fourth reaction unit (500) along the flow path.

[0048] The second reaction unit (300) performs secondary reforming of the primary reformed gas supplied from the first reactor (200), and the secondary reformed gas may include hydrogen and unreacted gases such as carbon dioxide and carbon monoxide.

[0049] In detail, the second reaction unit (300) generates a secondary reformed gas by performing a methane reforming reaction under a catalyst with the first reformed gas containing the unreacted gas supplied from the first reaction unit (200), and requires reaction heat of 600 to 900°C to perform the methane reforming reaction. At this time, since the temperature of the first reformed gas supplied from the first reaction unit (200) is 500 to 900°C, the methane reforming reaction can be performed without a separate heat supply device.

[0050] At this time, it is preferable to use a catalyst such as Ni-perovskite, which has excellent carbon deposition resistance and oxidation reaction. For example, the perovskite catalyst may be Ni-BZY (Yttria-doped barium zirconate).

[0051] The third reaction unit (400) receives the second reformed gas generated in the second reaction unit (300) to generate electricity and water, and may be a solid oxide fuel cell including a first fuel electrode (410), a first solid electrolyte layer (420), and a first air electrode (430). At this time, a sealing material (440) sealing the first fuel electrode (410), the first solid electrolyte layer (420), and the first air electrode (430) may be further included, and contact between air and hydrogen may be prevented by the sealing material (440), thereby creating an oxidation-reduction atmosphere.

[0052] The first fuel electrode (410) generates electrons and water by oxidizing hydrogen in the second reformed gas, and the first air electrode (430) receives electrons from the first fuel electrode (410) and reacts with external air to generate oxygen ions. The reactions occurring at the first fuel electrode (410) and the first air electrode (430) are as shown in Chemical Reaction Scheme 1 below.

[0053] Chemical equation 1.

[0054] First fuel electrode: H2+ O 2- → H2O + 2e-

[0055] First air electrode: 1 / 2O2+ 2e - → O 2-

[0056] In addition, an air inlet (450) may be arranged to supply air to the first air electrode (430), and an air discharge unit (460) may be arranged to discharge unreacted air and nitrogen that have not reacted in the first air electrode (430). At this time, the temperature of the air introduced through the first air inlet (450) is 25°C, but the temperature of the air discharged to the outside by reaction may be about 800°C.

[0057] The first solid electrolyte layer (420) receives oxygen ions from the first air electrode (430) and supplies them to the first fuel electrode (410). It is preferable to arrange an oxygen ion conductor to ensure smooth conduction of oxygen ions at 700 to 900°C. For example, it is preferable to use YSZ (Yttria-stabilized Zirconia) or GDC (Gadolinia-doped ceria) as the first solid electrolyte layer (430).

[0058] Meanwhile, the oxygen ions transferred to the first fuel electrode (410) react with the hydrogen ions to produce water (H2O, steam), and it is preferable that the water be supplied to the fourth reaction unit (500) together with unreacted gas (carbon dioxide, carbon monoxide). At this time, as the oxygen ions and hydrogen ions react at the first fuel electrode (410), reaction heat of 700 to 900°C is generated, and it is preferable that the generated heat be supplied to the fourth reaction unit (500).

[0059] The fourth reaction unit (500) receives unreacted gas containing carbon monoxide and carbon dioxide, heat, and water from the third reaction unit (400) to produce hydrogen, and may be a solid oxide water electrolysis cell including a second air electrode (510), a second solid electrolyte layer (520), and a second fuel electrode (530). At this time, a sealing material (540) sealing the second fuel electrode (510), the second solid electrolyte layer (520), and the second air electrode (530) may be further included, and contact between air and hydrogen may be prevented by the sealing material (540), thereby creating an oxidation-reduction atmosphere.

[0060] In the case of conventional solid oxide electrolysis cells, since the reactant (water) and product (hydrogen) exist together in the fuel electrode, a hydrogen extraction process was essential to separate the generated hydrogen.

[0061] In addition, there is a problem that the overall efficiency is reduced because carbon dioxide, an unreacted gas, exists in the fuel electrode, requiring an additional pressure swing adsorption (PSA) separation process. Therefore, it is preferable to apply a proton solid oxide electrolysis cell to the solid oxide electrolysis cell of the present invention.

[0062] In detail, the second air electrode (510) uses unreacted gas containing carbon monoxide and carbon dioxide supplied from the third reaction unit (400) as fuel, electrolyzes water (H20, steam) to separate it into cations, oxygen, and electrons, and produces hydrogen at the second fuel electrode (510). The reactions occurring at the second fuel electrode (510) and the second air electrode (530) are as shown in Chemical Reaction Formula 2 below.

[0063] Chemical equation 2.

[0064] Second fuel electrode: 2H + + 2e - → H2

[0065] Second air electrode: H2O → 2H + + 2e -+ 1 / 2O2

[0066] In addition, the second solid electrolyte layer (520) transfers cations from the second air electrode (510) to the second fuel electrode (530). It is preferable to place a cation conductor in the solid electrolyte layer (520) to ensure smooth conduction of cations at 500 to 700°C. For example, it is preferable to use BCY (Yttria-doped barium cerate) or BZY (Yttria-doped barium zirconate) as the second solid electrolyte layer (530).

[0067] Specifically, the second fuel electrode (530) can generate hydrogen through a reaction between cations and electrons received from the second air electrode (510). At this time, it is preferable that a hydrogen discharge unit (560) be arranged on the upper portion of the second fuel electrode (530) to recover the generated hydrogen.

[0068] As hydrogen is generated in the second fuel electrode (530), the location where the reactant (H2O) is supplied and the location where the product (H2) is recovered are different, so that a separate hydrogen extraction process does not need to be performed, and an additional separation process to remove carbon dioxide, which is an unreacted gas, does not need to be performed, which has the effect of improving the efficiency of the process.

[0069] The biogas-based electrochemical hydrogen extraction separation system according to the present invention further includes a gas discharge unit (120). Unreacted gas containing carbon monoxide, carbon dioxide, and oxygen that has not reacted in the fourth reaction unit (400) can be discharged to the outside through the gas discharge unit (120) along a path.

[0070] Meanwhile, the third reaction unit (400) and the fourth reaction unit (500) can be stacked and electrically connected to form a modular stack. Specifically, a plurality of third reaction units (400) can be stacked and electrically connected, and a plurality of fourth reaction units (500) can be stacked and electrically connected to form a modular stack. At this time, the reaction heat generated in the third reaction unit (400) and the fourth reaction unit (500) can be re-supplied to the first reaction unit (200) and the second reaction unit (300) through a flow path to form an optimized heat recovery system.

[0071] The power converter (600) can receive electricity generated in the third reaction unit (300) and supply electricity to the first reaction unit (200) and the fourth reaction unit (500). Specifically, since electricity is required for the plasma reaction in the first reaction unit (200), a plasma reforming reaction can be performed by supplying electricity generated in the third reaction unit (300) through the power converter (600). In addition, electrolysis can be performed by supplying electricity generated in the third reaction unit (300) to the fourth reaction unit (500) through the power converter (600).

[0072] Figure 3 is a schematic diagram showing the temperature distribution of a biogas-based electrochemical hydrogen extraction separation system according to one embodiment of the present invention.

[0073] Below, the operation method of a biogas-based electrochemical hydrogen extraction separation system and the reaction temperature distribution according to operation are described.

[0074] In order to operate the above biogas-based electrochemical hydrogen extraction and separation system (100), it can be configured to include a fuel supply stage, a first reforming stage, a second reforming stage, an electricity generation stage, and a hydrogen generation stage.

[0075] The above fuel supply step supplies fuel to the first reaction unit (200), and biogas can be supplied as fuel through the fuel supply unit (110). At this time, the temperature of the fuel supplied to the first reaction unit (200) is preferably room temperature.

[0076] The first reforming step generates a first reformed gas by reforming the biogas supplied from the fuel supply unit (110), and the first reforming step may generate the first reformed gas by applying plasma as a reforming means. At this time, the first reformed gas may include hydrogen, water, and unreacted gases (carbon monoxide, carbon dioxide). In addition, reaction heat is generated as the first reforming step is performed. The reaction heat is 800 to 900°C, and the reaction heat may be supplied to the second reaction unit (300), the third reaction unit (400), and the fourth reaction unit (500) along the flow path to preheat each reaction unit.

[0077] The second reforming step generates a second reformed gas by reforming the first reformed gas for the second time. The first reformed gas can be supplied to a second reaction unit (300) including a catalyst to generate a second reformed gas through a methane reforming reaction. At this time, the second reformed gas is hydrogen and may also include unreacted gas. In addition, reaction heat is generated as the second reforming step is performed. The reaction heat is approximately 800°C, and is preferably supplied to the third reaction unit (400) together with the second reformed gas.

[0078] The above-described electricity generation step can generate electricity and water through an electrochemical reaction by receiving the second reformed gas. Specifically, hydrogen supplied to the first fuel electrode (410) is oxidized to form electrons and hydrogen ions. The first air electrode (430) receives electrons from the first fuel electrode (410) and reacts with external air to generate oxygen ions. The oxygen ions can be transferred from the first air electrode (430) to the first fuel electrode (410) through the first solid electrolyte layer (420) and react with the hydrogen ions to form water. At this time, the electricity formed by the reaction is supplied to the power converter (600). It is preferable that the supplied electricity be supplied to the first reaction unit (200) and the fourth reaction unit (500), and if a large amount of electricity is generated, it can be stored in a separate external storage device. In addition, when the above-mentioned electricity generation step is performed, reaction heat of about 800°C is generated, and it is preferable that the reaction heat be supplied to the fourth reaction unit (500) and used as reaction heat when performing the hydrogen generation step.

[0079] The above hydrogen generation step can produce hydrogen by receiving unreacted gas including carbon monoxide and carbon dioxide formed in the above electricity generation step, heat, and water.

[0080] Specifically, the unreacted gas fuel containing carbon monoxide and carbon dioxide is used in the second air electrode (510), and water (steam) is electrolyzed to separate it into cations, oxygen, and electrons. The cations formed from the second air electrode (510) are transferred to the second fuel electrode (530) through the second solid electrolyte layer (520), and the cations and electrons transferred from the second air electrode (510) can react in the second fuel electrode (530) to generate hydrogen. At this time, it is preferable to recover the generated hydrogen through the hydrogen discharge unit (560).

[0081] Meanwhile, the biogas-based electrochemical hydrogen extraction and separation system according to the present invention further includes a gas discharge unit (120). Unreacted gas containing carbon monoxide and carbon dioxide that has not reacted in the fourth reaction unit (400) can be discharged to the outside through the gas discharge unit (120) along a path. At this time, the temperature of the unreacted gas discharged to the outside can be approximately 600°C.

[0082] As described above, the present invention has the effect of providing a biogas-based electrochemical hydrogen extraction separation system.

[0083] Specifically, the present invention provides a biogas-based electrochemical hydrogen extraction and separation system that supplies biogas heated and reformed by plasma as fuel for a solid oxide fuel cell to generate water and electricity, and electrolyzes the generated water to produce hydrogen.

[0084] Additionally, direct reforming of biogas has the effect of reducing carbon deposition on the fuel electrode of a solid oxide fuel cell, thereby maintaining long-term stability.

[0085] Additionally, by using biogas, a renewable resource, as fuel, it has the effect of increasing resource reuse and energy efficiency.

[0086] In addition, reforming is performed using the high-temperature heat generated by plasma without using an external burner, and by operating a solid oxide fuel cell and a solid oxide water electrolysis cell, there is an effect of reducing energy loss and increasing energy efficiency.

[0087] Although this specification describes only a few examples among various embodiments performed by the inventors of the present invention, the technical idea of ​​the present invention is not limited or restricted thereto, and can be modified and implemented in various ways by those skilled in the art.

[0088] [Explanation of symbols]

[0089] 110: Fuel supply section, 120: Gas exhaust section

[0090] 200: First Reaction Section,

[0091] 300: Second Reaction Section

[0092] 400: third reaction section, 410: first fuel electrode, 420: first solid electrolyte layer, 430: first air electrode, 440: sealant, 450: air inlet, 460: air outlet

[0093] 500: 4th reaction section, 510: 2nd air electrode, 520: 2nd solid electrolyte layer, 530: 2nd fuel electrode, 540: sealant, 560: hydrogen discharge section

Claims

1. In a biogas-based electrochemical hydrogen extraction and separation system including a solid oxide fuel cell and a solid oxide water electrolysis cell, Fuel supply unit that supplies biogas as fuel; A first reaction unit that reforms biogas supplied through the fuel supply unit to produce a first reformed gas; A second reaction unit that reforms the first reformed gas for the second time to produce a second reformed gas; A third reaction unit that generates electricity by receiving the second reformed gas generated in the second reaction unit; A fourth reaction unit that receives unreacted gas generated in the third reaction unit and uses it as fuel, and receives steam generated in the third reaction unit and generates hydrogen; and A power converter that receives electricity generated in the third reaction section and supplies electricity to the first reaction section and the fourth reaction section; Biogas-based electrochemical hydrogen extraction and separation system.

2. In paragraph 1, The first reaction unit further includes a first reactor that uses plasma as a reforming means, The first reactor reforms the biogas to produce a first reformed gas and a heat source, The first reaction section is disposed below the second reaction section. Biogas-based electrochemical hydrogen extraction and separation system.

3. In paragraph 1, The above first reformed gas contains methane, carbon dioxide, carbon monoxide, hydrogen and steam, The second reaction unit receives the first reformed gas generated in the first reaction unit and reforms it into a second reformed gas containing hydrogen, carbon dioxide, and carbon monoxide. Biogas-based electrochemical hydrogen extraction and separation system.

4. In paragraph 3, The second reaction section is provided with a catalyst to react with the first reformed gas, The above catalyst comprises Ni-perovskite, Biogas-based electrochemical hydrogen extraction and separation system.

5. In paragraph 1, The third reaction unit receives the second reformed gas and generates electricity and water, The third reaction section above is, A first fuel electrode in which hydrogen in the second reformed gas is oxidized to generate electrons and hydrogen ions; A first air electrode that receives electrons from the first fuel electrode and reacts with external air to generate oxygen ions; A first solid electrolyte layer that receives oxygen ions from the first air electrode and supplies them to the first fuel electrode; An air inlet for introducing air into the upper portion of the first air electrode; and An air exhaust section through which unreacted air is exhausted; Biogas-based electrochemical hydrogen extraction and separation system.

6. In paragraph 1, The fourth reaction unit receives unreacted gas including carbon monoxide and carbon dioxide, heat, and water from the third reaction unit to produce hydrogen. The above fourth reaction section, A second air electrode that uses the unreacted gas containing the above carbon monoxide and carbon dioxide as fuel and electrolyzes steam to separate it into cations, oxygen, and electrons; A second solid electrolyte layer that transfers cations from the second air electrode to the second fuel electrode; A second fuel electrode in which cations and electrons received from the second air electrode react to produce hydrogen; and It includes a hydrogen discharge unit that discharges hydrogen generated in the second fuel electrode to the outside; Biogas-based electrochemical hydrogen extraction and separation system.

7. In paragraph 1, Preheating the second reaction section, the third reaction section, and the fourth reaction section with the high temperature heat generated in the first reaction section. Biogas-based electrochemical hydrogen extraction and separation system.

8. In the operating method of a biogas-based electrochemical hydrogen extraction separation system, Fuel supply stage that supplies biogas as fuel; A first reforming step for generating a first reformed gas by reforming biogas supplied through the above fuel supply unit; A second reforming step of reforming the first reformed gas for the second time to produce a second reformed gas; An electricity generation step for generating electricity by supplying the second reformed gas generated in the second reforming step; and A hydrogen generation step for supplying unreacted gas generated in the above electricity generation step and using it as fuel, and for supplying steam generated in the above electricity generation step and generating hydrogen; including; The electricity generated in the above electricity generation step is supplied to the first reforming step and the hydrogen generation step. Method for operating a biogas-based electrochemical hydrogen extraction and separation system.

9. In paragraph 8, The above first reforming step generates a first reformed gas by applying plasma as a reforming means, The above first reformed gas contains hydrogen, water and unreacted gas (carbon monoxide, carbon dioxide). Method for operating a biogas-based electrochemical hydrogen extraction and separation system.

10. In paragraph 9, The above second reforming step supplies the first reforming gas to the functional catalyst layer to generate a second reforming gas, The above second reformed gas contains hydrogen and unreacted gas (carbon monoxide, carbon dioxide). Method for operating a biogas-based electrochemical hydrogen extraction and separation system.

11. In paragraph 8, The electricity generation stage receives the second reformed gas and generates electricity and water. In the first fuel electrode, hydrogen in the second reformed gas is oxidized to form electrons and hydrogen ions. At the first air electrode, electrons are transferred from the first fuel electrode and react with external air to generate oxygen ions. The above oxygen ions are transferred from the first air electrode to the first fuel electrode through the first solid electrolyte layer, The oxygen ions transferred to the first fuel electrode react with the hydrogen ions to form water. Method for operating a biogas-based electrochemical hydrogen extraction and separation system.

12. In paragraph 11, The hydrogen generation stage produces hydrogen by supplying unreacted gas, heat, and water containing carbon monoxide and carbon dioxide formed in the electricity generation stage. In the second air electrode, the unreacted gas containing the carbon monoxide and carbon dioxide is used as fuel and steam is electrolyzed to separate it into cations, oxygen and electrons. The cations formed from the second air electrode are transferred to the second fuel electrode through the second solid electrolyte layer, In the second fuel electrode, the cations and electrons received from the second air electrode react to produce hydrogen. Method for operating a biogas-based electrochemical hydrogen extraction and separation system.

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