In-situ hydrogen purification device and method in underground hydrogen storage wellbore based on selective dissolution of carbon dioxide

Abstract

The application belongs to the technical field of underground hydrogen storage engineering, and discloses an in-situ hydrogen purification device and method in a wellbore for underground hydrogen storage based on selective dissolution of carbon dioxide, which solves the problem of reduced hydrogen purity and increased ground separation load caused by mixing of carbon dioxide in produced gas when carbon dioxide is used as cushion gas for underground hydrogen storage. The in-situ hydrogen purification device in the wellbore for underground hydrogen storage comprises a produced wellbore module, a water phase medium injection module, a gas-liquid contact separation module in the wellbore, a water phase enriched carbon dioxide discharge module and a purified hydrogen production module; the gas-liquid contact separation module in the wellbore is arranged in the interior of the production wellbore, and is used for providing a gas-liquid contact space for the produced mixed gas and the water phase medium, and completing the mass transfer absorption process of carbon dioxide from the gas phase to the water phase in the interior of the wellbore. The application can fully utilize the wellbore space, reduce the arrangement requirement of large ground separation equipment, and improve the purity of the produced hydrogen.

Description

Technical Field

[0001] This invention belongs to the field of underground hydrogen storage engineering technology, and particularly relates to an in-situ hydrogen purification device and method in underground hydrogen storage wellbore based on selective carbon dioxide dissolution. Background Technology

[0002] Against the backdrop of reducing greenhouse gas emissions and meeting continuously growing energy demands, hydrogen energy, with its clean, efficient, and low-carbon characteristics, is considered an important energy carrier for achieving energy transition and carbon neutrality. However, the large-scale application of hydrogen is still limited by storage technology. While existing methods such as high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and chemical hydrogen storage can achieve hydrogen storage on a certain scale, they generally suffer from problems such as limited storage capacity, high energy consumption, complex equipment, or low release efficiency, making it difficult to meet future large-scale, long-term hydrogen storage needs.

[0003] Underground hydrogen storage technology utilizes underground geological structures such as salt caverns, depleted oil and gas reservoirs, and aquifers as storage spaces, enabling large-scale, long-term hydrogen storage and flexible extraction during peak energy demand periods. Compared with traditional hydrogen storage methods, underground hydrogen storage has advantages such as large storage capacity, good geological sealing, high operational safety, and the ability to utilize existing oil and gas infrastructure. Therefore, it is considered an important supporting technology for the future large-scale application of hydrogen energy.

[0004] In underground hydrogen storage, a cushion gas layer is often required to maintain reservoir pressure and reduce working gas loss. Carbon dioxide, due to its wide availability, ability to combine with carbon sequestration, and high density, can be used as a potential cushion gas layer. However, during the injection-production cycle, hydrogen and carbon dioxide mix within the reservoir, resulting in a certain proportion of carbon dioxide in the produced gas, reducing hydrogen purity and increasing surface separation costs.

[0005] Existing hydrogen and carbon dioxide separation technologies mainly include pressure swing adsorption (PSA), membrane separation, cryogenic separation, chemical absorption, and physical absorption. Related patents and processes include solutions combining membrane separation and carbon dioxide separation units for hydrogen and carbon dioxide recovery, but these are mostly concentrated in surface hydrogen production or syngas purification scenarios, occupying significant surface space and increasing the construction, operation, and maintenance costs of surface stations. For underground hydrogen storage stations, especially in situations with limited well site space or requiring multi-well operation, additional large-scale gas separation devices would increase system complexity and engineering implementation difficulty. Summary of the Invention

[0006] One objective of this invention is to provide an in-situ hydrogen purification device for underground hydrogen storage wellbores based on selective dissolution of carbon dioxide, which effectively solves the problem that when carbon dioxide is used as a cushion gas for underground hydrogen storage, the produced gas is mixed with carbon dioxide, resulting in a decrease in hydrogen purity and an increase in surface separation load.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an in-situ hydrogen purification device in underground hydrogen storage wellbore based on selective dissolution of carbon dioxide, including a wellbore extraction module, an aqueous medium injection module, a gas-liquid contact separation module in the wellbore, an aqueous phase enrichment carbon dioxide discharge module, and a purified hydrogen extraction module.

[0008] The production wellbore module, also known as the production wellbore in an underground hydrogen storage project, is used to transport produced gas from the reservoir to the surface. The aqueous medium injection module provides an aqueous medium to the gas-liquid contact separation module inside the wellbore. The gas-liquid contact separation module is located inside the production wellbore and provides a gas-liquid contact space for the produced mixed gas and the aqueous medium, and completes the mass transfer and absorption process of carbon dioxide from the gas phase to the aqueous phase inside the wellbore. The aqueous phase enriched carbon dioxide discharge module collects and discharges the aqueous medium that has absorbed carbon dioxide. The purified hydrogen production module is located at the top of the production wellbore module and is used to transport the hydrogen-rich gas, which has been purified in situ inside the production wellbore, to the surface.

[0009] Furthermore, the gas-liquid contact separation module inside the wellbore includes a spray structure, a packing structure, a baffle structure, and a porous distribution structure. The spray structure is located at the upper part of the gas-liquid contact separation module inside the wellbore, and includes a spray pipeline connected to the aqueous medium injection module, as well as nozzles, spray holes, or spray distribution chambers. The packing structure is located below the spray structure and includes a packing support and a packing body. The packing body is used to provide a film-forming and dispersing surface for the aqueous medium, so that the aqueous medium forms a liquid film on the surface of the packing body and fully contacts the rising produced mixed gas, thereby promoting the transfer of carbon dioxide from the gas phase to the aqueous phase.

[0010] The baffle structure is located below the packing structure and includes one or more baffles arranged axially along the production wellbore; it is used to change the flow direction of the produced mixed gas and water phase medium, so that the produced mixed gas and water phase medium undergo flow around, disturbance and redistribution within the wellbore.

[0011] The porous distribution structure is located at the lower part of the gas-liquid contact separation module inside the wellbore, and includes a porous plate, a screen tube, a screen mesh or a perforated support component; the porous distribution structure is used to uniformly distribute the produced mixed gas entering the gas-liquid contact separation module inside the wellbore, so that the produced mixed gas enters the baffle structure, the packing structure and the spray structure evenly.

[0012] Furthermore, the aqueous medium is clean water, formation water, produced water, reinjected water, saline water, or other aqueous medium suitable for the wellbore environment of underground hydrogen storage production.

[0013] Furthermore, the aqueous phase enriched carbon dioxide discharge module includes a discharge outlet, an independent discharge pipeline, and a wellhead discharge interface. The discharge outlet is located in the collection area below the baffle structure. A liquid-blocking component, a collection trough, an annular collection cavity, or a liquid seal structure is provided between the collection area and the porous distribution structure. The aqueous phase medium enriched with carbon dioxide collects in the collection area below the baffle structure after passing through the spray structure, the packing structure, and the baffle structure. It then enters the independent discharge pipeline through the discharge outlet and is discharged through the wellhead discharge interface.

[0014] Furthermore, the baffle plate is an inclined plate, a corrugated plate, an interlaced plate, an arc-shaped plate, a perforated baffle, or other plate-like structures that can change the gas-liquid flow path.

[0015] Furthermore, the packing body is a structured packing, bulk packing, porous packing, corrugated packing, mesh packing, honeycomb packing, or other packing structures that can increase the gas-liquid contact area.

[0016] Another objective of this invention is to provide a method for in-situ hydrogen purification within underground hydrogen storage wells based on the selective dissolution of carbon dioxide, applicable to the in-situ hydrogen purification device within underground hydrogen storage wells described in the above embodiments. During the underground hydrogen extraction process, the extracted mixed gas first enters the extraction well module and flows upward along the well. When the extracted mixed gas passes through the gas-liquid contact separation module within the well, the aqueous medium injection module provides an aqueous medium to the gas-liquid contact separation module within the well, ensuring sufficient contact between the extracted mixed gas and the aqueous medium. Since the solubility of carbon dioxide in the extracted mixed gas is higher than that of hydrogen in the aqueous phase, carbon dioxide preferentially transfers from the gas phase to the aqueous phase, while most of the hydrogen remains in the gas phase. Subsequently, the aqueous medium enriched with carbon dioxide is discharged through the aqueous phase enriched carbon dioxide discharge module or treated and reinjected, while the hydrogen-rich gas is extracted to the surface through the purified hydrogen extraction module.

[0017] Furthermore, the extracted mixed gas includes hydrogen and carbon dioxide, wherein the carbon dioxide originates from the carbon dioxide cushion gas used in the underground hydrogen storage process.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are: (1) This invention integrates gas-liquid contact, mass transfer absorption and gas-liquid separation functions into an underground hydrogen storage production wellbore, making full use of the internal space of the wellbore so that the produced mixed gas containing hydrogen and carbon dioxide can fully contact the aqueous medium during the ascent. Since the solubility of carbon dioxide in the aqueous phase is significantly higher than that of hydrogen, carbon dioxide preferentially enters the aqueous phase, thereby achieving in-situ enrichment of carbon dioxide and preliminary purification of hydrogen in the wellbore.

[0019] (2) The present invention can make full use of the wellbore space, reduce the layout requirements of large-scale ground separation equipment, reduce the ground processing load, and improve the purity of extracted hydrogen, thereby improving the operating efficiency and economy of the underground hydrogen storage system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the in-situ hydrogen purification device inside the underground hydrogen storage well of the present invention.

[0021] Explanation of reference numerals in the attached diagram: Production wellbore module-1; Aqueous medium injection module-2; Gas-liquid contact separation module in the wellbore-3; Aqueous phase enrichment carbon dioxide discharge module-4; Purified hydrogen production module-5; Spray structure-6; Packing structure-7; Baffle structure-8; Porous distribution structure-9; Nozzle-61; Independent injection pipeline-21; Drainage outlet-41; Independent drainage pipeline-42. Detailed Implementation

[0022] Example 1: An in-situ hydrogen purification device within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution, such as... Figure 1 As shown, it includes a wellbore module 1, an aqueous medium injection module 2, a gas-liquid contact separation module 3 in the wellbore, an aqueous phase enrichment carbon dioxide discharge module 4, and a purified hydrogen production module 5.

[0023] Production wellbore module 1, or production wellbore in an underground hydrogen storage project, is located between the underground hydrogen storage reservoir and the surface wellhead. It is used to transport the produced mixed gas from the underground hydrogen storage reservoir to the surface. The produced mixed gas mainly consists of hydrogen and carbon dioxide. Hydrogen is the working gas in the underground hydrogen storage process, while carbon dioxide is the cushion gas used in the underground hydrogen storage process. During production, the produced mixed gas enters production wellbore module 1 from the underground hydrogen storage reservoir and flows upwards along the wellbore.

[0024] The gas-liquid contact separation module 3 is installed inside the production wellbore module 1, preferably in the middle of the wellbore or in the section of the wellbore near the wellhead. The gas-liquid contact separation module 3 is used to provide a gas-liquid contact space for the produced mixed gas and aqueous medium, and to complete the mass transfer and absorption process of carbon dioxide from the gas phase to the aqueous phase inside the wellbore.

[0025] The gas-liquid contact separation module 3 in the wellbore includes a spray structure 6, a packing structure 7, a baffle structure 8, and a porous distribution structure 9. (1) The spray structure 6 is located at the top of the gas-liquid contact separation module 3 in the wellbore, including a spray pipeline connected to the aqueous medium injection module 2, as well as nozzles 61, spray holes, or spray distribution chambers; after the pipeline of the aqueous medium injection module 2 enters from the wellhead, it is transported downward along an independent pipeline to the spray structure 6, and sprayed out at the top of the gas-liquid contact separation module 3 in the wellbore through nozzles 61 or spray holes. Through the spray structure 6, the aqueous medium is dispersed into droplets, liquid films, or fine liquid flows, thereby increasing the contact area between the aqueous medium and the produced mixed gas. (2) The packing structure 7 is located below the spray structure 6. The packing structure 7 includes a packing body and a packing support. The packing body can be a structured packing, bulk packing, porous packing, corrugated packing, mesh packing, honeycomb packing, or other structures that can increase the gas-liquid contact area. The packing support is used to support the packing body and prevent the packing from falling, shifting or blocking the lower channel in the wellbore. After the aqueous medium enters the packing structure 7 through the spray structure 6, a liquid film or dispersed liquid flow is formed on the surface of the packing. When the produced mixed gas passes through the gaps in the packing from bottom to top, it comes into full contact with the aqueous medium, so that carbon dioxide is transferred from the gas phase to the aqueous phase. (3) The baffle structure 8 is set below the packing structure 7. The baffle structure 8 includes one or more baffles arranged along the wellbore axis. The baffles can be inclined plates, corrugated plates, staggered plates, arc plates, perforated baffles or other plate-shaped structures that can change the gas-liquid flow path. The baffle structure 8 is used to change the flow direction of the produced mixed gas and the aqueous medium, so that the produced mixed gas and the aqueous medium are circulated, disturbed and redistributed in the wellbore, thereby prolonging the gas-liquid contact time and improving the efficiency of carbon dioxide transfer to the aqueous phase. After passing through the spray structure 6 and the packing structure 7, the aqueous medium continues to flow downward through the baffle structure 8 and gradually gathers below the baffle structure 8 to form an aqueous medium enriched with carbon dioxide. (4) A porous distribution structure 9 is installed at the lower part of the gas-liquid contact separation module 3 inside the wellbore. The porous distribution structure 9 includes a porous plate, a screen tube, a screen mesh, a perforated support, or other distribution structures with through holes. The porous distribution structure 9 is used to uniformly distribute the produced mixed gas entering the gas-liquid contact separation module 3 inside the wellbore from below, so that the produced mixed gas can enter the baffle structure 8, the packing structure 7, and the spray structure 6 more evenly.

[0026] The aqueous medium injection module 2 is used to provide aqueous medium to the gas-liquid contact separation module inside the wellbore. The aqueous medium injection module includes a wellhead injection interface, an independent injection pipeline 21, and a lower inlet connected to the spray structure 6. The independent injection pipeline 21 enters the production wellbore module 1 from the wellhead and extends downwards along the wellbore to the upper part of the gas-liquid contact separation module 3 inside the wellbore. The lower inlet is connected to the upper spray pipeline of the spray structure 6. After entering the spray structure 6 through the aqueous medium injection module 2, the aqueous medium is sprayed and distributed on the upper part of the gas-liquid contact separation module 3 inside the wellbore. The aqueous medium can be clean water, formation water, produced water, reinjection water, saline water, or other aqueous media suitable for the underground hydrogen storage wellbore environment. Preferably, the aqueous medium is formation water, produced water, or treated reinjection water compatible with the reservoir environment to reduce the impact of external fluids on the reservoir. Because carbon dioxide has a higher solubility in the aqueous phase than hydrogen, when the aqueous medium comes into contact with the extracted mixed gas, carbon dioxide preferentially dissolves into the aqueous phase, while most of the hydrogen remains in the gas phase.

[0027] The aqueous phase enriched carbon dioxide discharge module 4 is used to collect and discharge the aqueous phase medium after absorbing carbon dioxide. The aqueous phase enriched carbon dioxide discharge module 4 includes a discharge outlet 41, an independent discharge pipeline 42, and a wellhead discharge interface. The discharge outlet 41 is located below the baffle structure 8, preferably in the collection area below the baffle plate area. The carbon dioxide-enriched aqueous phase medium, after passing through the spray structure 6, the packing structure 7, and the baffle structure 8, collects below the baffle structure 8 and enters the independent discharge pipeline 42 through the discharge outlet 41. The independent discharge pipeline 42 extends upwards along the wellbore to the wellhead, and discharges the carbon dioxide-enriched aqueous phase medium from the wellbore through the wellhead discharge interface.

[0028] A liquid-blocking component, a liquid-collecting trough, an annular liquid-collecting cavity, or a liquid-sealing structure is provided between the liquid-collecting area at the bottom of the baffle structure 8 and the porous distribution structure 9, so that the falling aqueous medium is preferentially discharged through the liquid discharge outlet 41, preventing the aqueous medium from continuing to pass through the porous distribution structure 9 and entering the mixed gas inlet.

[0029] The aqueous phase enriched carbon dioxide discharge module 4 and the aqueous phase medium injection module 2 are set up independently. The lower inlet of the aqueous phase medium injection module 2 is connected to the upper part of the spray structure 6 and is used to supply the aqueous phase medium to the gas-liquid contact separation module 3 in the wellbore; the discharge outlet 41 of the aqueous phase enriched carbon dioxide discharge module 4 is located below the baffle structure 8 and is used to collect and discharge the aqueous phase medium after absorbing carbon dioxide. The two are not directly connected in the wellbore to avoid mixing between the newly injected aqueous phase and the enriched carbon dioxide aqueous phase.

[0030] The purified hydrogen production module 5 is located at the top of the production wellbore module 1 and is used to produce hydrogen-rich gas, after being processed by the gas-liquid contact separation module 3 inside the wellbore, to the surface. After the produced mixed gas passes through the gas-liquid contact separation module 3 inside the wellbore, a portion of the carbon dioxide is absorbed by the aqueous medium and enters the aqueous phase, increasing the hydrogen gas fraction in the gas phase, thus forming hydrogen-rich gas. The hydrogen-rich gas continues to flow upward along the production wellbore module 1 and is transported to the surface through the purified hydrogen production module 5.

[0031] Example 2: An in-situ hydrogen purification method within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution, applied to the in-situ hydrogen purification device within an underground hydrogen storage wellbore described in Example 1. During underground hydrogen extraction, the extracted mixed gas first enters the extraction wellbore module 1 and flows upwards along the wellbore. When the extracted mixed gas passes through the gas-liquid contact separation module 3 within the wellbore, the aqueous medium injection module 2 provides an aqueous medium to the gas-liquid contact separation module 3, ensuring sufficient contact between the extracted mixed gas and the aqueous medium. Since the solubility of carbon dioxide in the aqueous phase is higher than that of hydrogen, carbon dioxide preferentially transfers from the gas phase to the aqueous phase, while most of the hydrogen remains in the gas phase. Subsequently, the carbon dioxide-enriched aqueous medium is discharged through the aqueous carbon dioxide enrichment discharge module 4 or treated and reinjected, while the hydrogen-rich gas is extracted to the surface through the purified hydrogen extraction module 5.

[0032] This embodiment specifically includes the following steps: S1, during the underground hydrogen storage and extraction stage, the extracted mixed gas from the underground hydrogen storage reservoir enters the extraction wellbore module 1. The extracted mixed gas mainly includes hydrogen and carbon dioxide, wherein the carbon dioxide originates from the carbon dioxide cushion gas used in the underground hydrogen storage process.

[0033] S2. Under the influence of reservoir pressure or production pressure differential, the produced mixed gas flows upward along the produced wellbore module 1 and enters the lower part of the gas-liquid contact separation module 3 inside the wellbore. The produced mixed gas first passes through the porous distribution structure 9, which uniformly distributes the produced mixed gas within the wellbore cross-section, reducing local gas flow deviation.

[0034] S3. The aqueous medium enters the production wellbore module 1 through the aqueous medium injection module 2. The aqueous medium is transported downwards along the independent injection pipeline to the upper part of the gas-liquid contact separation module 3 inside the wellbore, and then enters the spray structure 6.

[0035] S4. The aqueous medium is sprayed out through the spray structure 6, forming droplets, liquid films, or dispersed liquid flows above the gas-liquid contact separation module 3 inside the wellbore. Simultaneously, the produced mixed gas enters the gas-liquid contact area below the spray structure 6 from bottom to top. The aqueous medium and the produced mixed gas form a counter-current contact.

[0036] S5. The extracted gas mixture and aqueous medium enter the packing structure 7. The aqueous medium forms a liquid film on the packing surface, and the extracted gas mixture flows upward along the packing gaps. Because the packing structure 7 provides a large gas-liquid contact area, carbon dioxide is transferred from the gas phase to the aqueous phase in this region, while hydrogen is mainly retained in the gas phase.

[0037] S6. The aqueous medium continues to flow downwards and enters the baffle structure 8. The baffle changes the flow path of the aqueous medium and the extracted mixed gas, causing disturbance, flow around, and redistribution of the gas and liquid phases, further extending the gas-liquid contact time and improving the carbon dioxide absorption efficiency.

[0038] S7. The aqueous medium that has absorbed carbon dioxide collects in the collection area below the baffle structure 8, forming an aqueous medium enriched with carbon dioxide. This carbon dioxide-enriched aqueous medium enters the aqueous carbon dioxide enrichment discharge module 4 through the discharge outlet 41 located below the baffle structure 8. The discharge outlet 41 is located below the baffle plate area and is not connected to the aqueous medium injection module 2.

[0039] The liquid collection area is connected to the liquid discharge outlet 41, which is located on the lower side wall of the liquid collection area. The outlet 41 is used to guide the carbon dioxide-enriched aqueous medium into the aqueous carbon dioxide-enriched discharge module 4. A liquid-blocking component, a liquid collection trough, an annular liquid collection cavity, or a liquid seal structure is provided between the liquid collection area and the porous distribution structure 9 to ensure that the falling aqueous medium is preferentially discharged through the liquid discharge outlet 41, preventing the aqueous medium from continuing to pass through the porous distribution structure 9 and entering the mixed gas inlet.

[0040] S8. The carbon dioxide-enriched aqueous medium is returned upwards to the wellhead through an independent drainage pipeline 42 and discharged through the wellhead discharge interface. The discharged carbon dioxide-enriched aqueous medium can be reinjected into the underground reservoir, transported to the surface treatment unit, or recycled as an aqueous medium after degassing and regeneration, depending on the project requirements.

[0041] S9. After being processed by the gas-liquid contact separation module 3 inside the wellbore, the carbon dioxide content in the gas phase decreases, while the hydrogen gas fraction increases, forming hydrogen-rich gas. The hydrogen-rich gas continues to flow upward along the production wellbore module 1 and is extracted to the surface through the purified hydrogen production module 5.

[0042] Through the above steps, in-situ preliminary separation of hydrogen and carbon dioxide within the wellbore is achieved before the produced gas reaches the surface. This implementation method can make full use of the internal space of the wellbore, reduce the need for large-scale gas separation equipment on the surface, reduce the surface separation load, improve the purity of produced hydrogen, and reduce the proportion of carbon dioxide cushion gas entering the surface treatment system with the produced gas.

[0043] Example 3: In this example, the aqueous absorption medium is produced water or treated reinjection water. After surface filtration, sand removal, or necessary water quality adjustment, the produced water is reinjected into the gas-liquid contact separation module 3 inside the wellbore through the aqueous medium injection module 2. The carbon dioxide-enriched aqueous medium, after absorbing carbon dioxide, is discharged through the carbon dioxide-enriched aqueous discharge module 4 and can be directly reinjected into the underground hydrogen storage reservoir or other suitable formations, or it can enter a surface regeneration device to remove carbon dioxide and be recycled. This method can reduce external water consumption, improve the utilization efficiency of the aqueous absorption medium, and enhance the coupling capability between the underground hydrogen storage system and the carbon dioxide sequestration or reinjection process.

[0044] Example 4: In this example, the packing structure 7, baffle structure 8, and porous distribution structure 9 in the gas-liquid contact separation module 3 inside the wellbore are adjusted according to the wellbore size, produced gas volume, aqueous absorption medium flow rate, and allowable pressure drop. For conditions with a large produced gas volume, the height of the packing structure 7 can be increased, the specific surface area of ​​the packing can be improved, or a multi-stage spray structure 6 can be added to increase the gas-liquid contact area. For conditions with limited wellbore space or requiring a lower pressure drop, a porous distribution structure 9 with a higher porosity and baffles with larger spacing can be used to reduce flow resistance. Through the above structural parameter adjustments, the gas-liquid contact separation module 3 inside the wellbore can adapt to different underground hydrogen storage wellbore conditions.

[0045] Through the above embodiments, this invention integrates spraying, packing, baffle, porous distribution, and liquid collection and discharge functions within the underground hydrogen storage wellbore, ensuring sufficient contact between the produced mixed gas and the aqueous medium as it rises within the wellbore. Since carbon dioxide is more soluble in the aqueous phase than hydrogen, carbon dioxide preferentially enters the aqueous phase and is discharged through the aqueous phase enrichment and carbon dioxide discharge module, while hydrogen is primarily retained in the gas phase and extracted through the hydrogen purification and extraction module. The device and method provided by this invention can achieve in-situ preliminary purification within the wellbore before the produced gas reaches the surface, improving the purity of the produced hydrogen, reducing the surface separation load, and enhancing the operating efficiency and economy of the underground hydrogen storage system.

[0046] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An in-situ hydrogen purification device within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution, characterized in that, It includes a wellbore module, an aqueous medium injection module, a gas-liquid contact separation module inside the wellbore, an aqueous phase enrichment carbon dioxide discharge module, and a purified hydrogen production module. The produced well module is the production well in the underground hydrogen storage project, used to transport the produced gas from the reservoir to the surface; The aqueous medium injection module is used to provide an aqueous medium to the gas-liquid contact separation module inside the wellbore. The gas-liquid contact separation module inside the wellbore is installed inside the production wellbore to provide a gas-liquid contact space for the produced mixed gas and water phase medium, and to complete the mass transfer and absorption process of carbon dioxide from the gas phase to the water phase inside the wellbore. The aqueous phase enrichment carbon dioxide discharge module is used to collect and discharge the aqueous phase medium that has absorbed carbon dioxide. The purified hydrogen production module is located at the top of the production well module and is used to transport the hydrogen-rich gas, which has been purified in situ inside the production well, to the surface.

2. The in-situ hydrogen purification device within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution according to claim 1, characterized in that, The gas-liquid contact separation module inside the wellbore includes a spray structure, a packing structure, a baffle structure, and a porous distribution structure; The spray structure is located above the gas-liquid contact separation module inside the wellbore, and includes a spray pipeline connected to the aqueous medium injection module, as well as nozzles, spray holes, or spray distribution chambers. The packing structure is located below the spray structure and includes a packing support and a packing body. The packing body is used to provide a film-forming and dispersion surface for the aqueous medium, so that the aqueous medium forms a liquid film on the surface of the packing body and fully contacts the rising produced mixed gas, thereby promoting the transfer of carbon dioxide from the gas phase to the aqueous phase. The baffle structure is located below the packing structure and includes one or more baffles arranged axially along the production wellbore; it is used to change the flow direction of the produced mixed gas and water phase medium, so that the produced mixed gas and water phase medium undergo flow around, disturbance and redistribution within the wellbore. The porous distribution structure is located at the lower part of the gas-liquid contact separation module inside the wellbore, and includes a porous plate, a screen tube, a screen mesh or a perforated support component; the porous distribution structure is used to uniformly distribute the produced mixed gas entering the gas-liquid contact separation module inside the wellbore, so that the produced mixed gas enters the baffle structure, the packing structure and the spray structure evenly.

3. The in-situ hydrogen purification device within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution according to claim 2, characterized in that, The aqueous medium is clean water, formation water, produced water, reinjected water, saline water, or other aqueous medium suitable for the wellbore environment of underground hydrogen storage production.

4. The in-situ hydrogen purification device within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution according to claim 2, characterized in that, The aqueous phase enriched carbon dioxide discharge module includes a discharge outlet, an independent discharge pipeline and a wellhead discharge interface. The discharge outlet is located in the collection area below the baffle structure. A liquid-blocking component, a collection trough, an annular collection cavity or a liquid seal structure is provided between the collection area and the porous distribution structure. The aqueous medium enriched with carbon dioxide collects in the liquid collection area below the baffle structure after passing through the spray structure, packing structure, and baffle structure. It then enters an independent drainage pipeline through the drainage outlet and is discharged through the wellhead discharge interface.

5. The in-situ hydrogen purification device within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution according to claim 4, characterized in that, The baffle plate is an inclined plate, corrugated plate, staggered plate, arc plate, perforated baffle, or other plate-like structure that can change the gas-liquid flow path.

6. The in-situ hydrogen purification device within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution according to claim 2, characterized in that, The packing body is a structured packing, bulk packing, porous packing, corrugated packing, mesh packing, honeycomb packing, or other packing structures that can increase the gas-liquid contact area.

7. A method for in-situ hydrogen purification within an underground hydrogen storage wellbore based on the selective dissolution of carbon dioxide, characterized in that, The in-situ hydrogen purification device applied to the underground hydrogen storage wellbore according to any one of claims 1-6; During underground hydrogen extraction, the extracted mixed gas first enters the extraction wellbore module and flows upward along the wellbore. When the extracted mixed gas passes through the gas-liquid contact separation module inside the wellbore, the aqueous medium injection module provides aqueous medium to the gas-liquid contact separation module inside the wellbore, so that the extracted mixed gas and the aqueous medium can fully contact each other. Since the solubility of carbon dioxide in the aqueous phase is higher than that of hydrogen in the extracted mixed gas, carbon dioxide preferentially transfers from the gas phase to the aqueous phase, while most of the hydrogen is retained in the gas phase. Subsequently, the aqueous medium enriched with carbon dioxide is discharged through the aqueous phase carbon dioxide enrichment discharge module or treated and reinjected, while the hydrogen-rich gas is extracted to the surface through the hydrogen purification extraction module.

8. The in-situ hydrogen purification method within an underground hydrogen storage wellbore based on selective carbon dioxide dissolution according to claim 7, characterized in that, The extracted mixed gas includes hydrogen and carbon dioxide, wherein the carbon dioxide originates from the carbon dioxide cushion gas used in the underground hydrogen storage process.

Images