A system for carbon dioxide sequestration in a mined-out area of a well and a method of use

Abstract

The present application relates to carbon sequestration technology field, the present application discloses a kind of underground goaf carbon dioxide sequestration system and use method, including the V-shaped support band of supporting goaf roof strata multiple, and the filling module for filling in the cavity separated to the V-shaped support band, exhaust pipe, the filling module includes buffer tank, dynamic pressure balance contraction type hose, heat preservation liquid fluid conveying mechanism, heat preservation liquid pressure balance discharge, liquid backflow mechanism, the discharge pipeline has pressure temperature adjustment straight pipe;With the synchronous operation form of support, filling, the flowability of supercritical carbon dioxide is utilized, the adsorption effect of porous material is improved, and the prefabricated porous material is filled with the pushing effect of high-pressure supercritical carbon dioxide, so that the final filling cavity contains porous material for supporting, carbon dioxide adsorbed in the pore of porous material, and gaseous carbon dioxide filled in the gap between adjacent porous material.

Description

Technical Field

[0001] This invention relates to the field of carbon sequestration technology, specifically a carbon dioxide sequestration system and its application method in underground goaf areas. Background Technology

[0002] Mining goaf can be reused for carbon dioxide geological sequestration. Currently, there are two main methods for sequestration.

[0003] The first method involves supporting the goaf through a support structure, dividing the space into multiple cavities, and then injecting pressurized gaseous carbon dioxide into the cavities for sealed storage. This method has a large carbon dioxide storage capacity and is simple to operate, but the problem is that the goaf still has multiple sealed cavities, resulting in insufficient support for the goaf.

[0004] The second method involves carbon dioxide fixation through backfilling and carbon dioxide storage. A Chinese patent (CN115341952A) discloses a carbon dioxide adsorption-solidification and storage method based on backfilling of solid waste in goaf areas. This patent involves crushing coal gangue, fly ash, and construction waste to obtain dry filling material. The dry filling material is then mixed evenly, and water is added to create a filling slurry. This slurry is injected into the goaf through the filling holes. Simultaneously, CO2 is introduced into the grouting pipeline to seal the CO2. This method can effectively improve the support effect while simultaneously sealing carbon dioxide; however, the storage capacity is too small. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon dioxide sequestration system and its usage method in underground goaf areas to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A carbon dioxide sequestration system for underground goaf areas includes multiple V-shaped support strips that support the roof strata of the goaf area, as well as a filling module and an exhaust pipe for filling the cavities separated by the V-shaped support strips.

[0008] The filling module includes a buffer tank, a dynamic pressure-balanced contractile hose, a thermal insulation liquid conveying mechanism, a thermal insulation liquid pressure-balanced discharge port, and a liquid return mechanism. The buffer tank is injected with porous adsorbent backfill material and supercritical carbon dioxide fluid through a porous filler particle conveying pipe and a supercritical carbon dioxide fluid conveying pipe, respectively. The bottom of the buffer tank is provided with a discharge pipe, which has a pressure and temperature adjustment straight pipe. The dynamic pressure-balanced contractile hose is fixedly connected to the inside of the pressure and temperature adjustment straight pipe. The top of the pressure and temperature adjustment straight pipe is provided with a backfill pipe. The front end of the discharge pipe is provided with a closing valve. The top of the dynamic pressure-balanced contractile hose is fixedly connected to the backfill pipe. The injection flow rate of the porous filler particle conveying pipe and the supercritical carbon dioxide fluid conveying pipe is equal to the discharge flow rate of the backfill pipe.

[0009] The top pipe of the pressure and temperature adjusting straight pipe is connected to the heat insulation liquid conveying mechanism. A temperature exchange and pressure boosting chamber is formed between the pressure and temperature adjusting straight pipe and the dynamic pressure balance contraction hose. The temperature exchange and pressure boosting chamber is connected to the end opening of the discharge pipe. The end opening of the discharge pipe is provided with the heat insulation liquid pressure balance discharge port. The liquid discharged from the heat insulation liquid pressure balance discharge port is recovered by the liquid return mechanism and then heated by the heat insulation liquid conveying mechanism to form a closed loop.

[0010] The exhaust pipe passes through the V-shaped support belt and communicates with the cavity. The other end of the exhaust pipe is connected to the carbon dioxide recovery device. A pressure sensor and a gas concentration sensor are installed inside the exhaust pipe.

[0011] As a further aspect of the present invention: when the dynamic pressure balance retractable hose is in an open discharge state, the internal pressure of the buffer tank is higher than 7.3 MPa.

[0012] As a further aspect of the present invention, the liquid temperature inside the temperature-changing and pressurizing chamber is higher than 31 degrees Celsius.

[0013] As a further aspect of the present invention: the V-shaped support belt includes a V-shaped plate and an operating end plane, and when multiple V-shaped support belts are fixed, the operating end plane is located on the same horizontal line.

[0014] As a further aspect of the present invention: a method for using a carbon dioxide sequestration system in an underground goaf, comprising:

[0015] S1: Mix crushed gangue, fly ash, cement and water in a certain proportion to form a paste to obtain an adsorption support material;

[0016] S11: Place the paste into the V-shaped flange support mold, and remove it after it dries and hardens to obtain multiple V-shaped support strips. Multiple injection holes are opened at equal intervals on the inclined side of the V-shaped support strip. The injection holes are located at the top of the inclined side of the V-shaped support strip, and venting holes are opened at the top corner of the V-shaped support strip.

[0017] S12: Prepare the paste using a granulator or spherical mold, and remove it after drying and hardening to obtain multiple porous adsorbent backfill materials;

[0018] S2: After installing and sealing the innermost V-shaped support belt, push the filling module into the open triangular operating face formed by the V-shaped support belt and the goaf. The V-shaped support belt and the goaf form two triangular filling areas for large-scale filling. The filling material is a supercritical porous adsorption backfill mixed fluid.

[0019] S3: The porous filler particle conveying pipeline delivers the porous adsorbent backfill material into the buffer tank. The supercritical carbon dioxide fluid conveying pipeline pressurizes the supercritical carbon dioxide fluid to a pressure greater than 7.3 MPa when it is delivered into the buffer tank. Once a certain liquid level is reached inside the buffer tank, the closed valve is opened. Due to the pressure inside the buffer tank, the supercritical porous adsorbent backfill material mixture is pressurized downwards, causing the dynamic pressure balance contraction hose to open under pressure. The pressure inside the buffer tank decreases, and simultaneously, the insulation liquid conveying mechanism injects... When the liquid enters the temperature exchange and pressurization chamber, it is affected by the pressure balance discharge port of the insulation liquid. The inside of the temperature exchange and pressurization chamber applies a reaction force to the dynamic pressure balance contraction hose until the internal pressure of the dynamic pressure balance contraction hose is greater than 7.3 MPa, and the dynamic pressure balance contraction hose is in communication with the backfill pipe. The backfill pipe is connected to the injection port of the V-shaped support belt. The supercritical porous adsorbent backfill material mixed fluid reaching the backfill pipe is affected by the pressure reduction. After falling into the cavity area formed by the V-shaped support belt, the porous adsorbent backfill material falls into the cavity area to fill it, and the supercritical carbon dioxide is converted into gas to fill the cavity.

[0020] S4: The original air in the goaf is driven out by carbon dioxide and squeezed out of the goaf through the reserved exhaust holes, and discharged through the exhaust pipe. The exhaust pipe monitors the pressure of the discharged gas and the concentration of carbon dioxide. When the pressure and concentration reach the specified threshold, the exhaust pipe is closed and the backfill pipe is withdrawn and closed.

[0021] As a further aspect of the present invention: the diameter of the porous adsorption backfill material in step S12 is smaller than the diameter of the injection hole in step S11.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This method employs a simultaneous support and filling operation, utilizing the fluidity of supercritical carbon dioxide to enhance the adsorption effect of porous materials. The pre-fabricated porous material is filled by the pushing action of high-pressure supercritical carbon dioxide, resulting in a final filled cavity containing supporting porous material, carbon dioxide adsorbed within the pores of the porous material, and gaseous carbon dioxide filling the gaps between adjacent porous materials. The entire operation is simple to execute, and compared to the carbon dioxide fixation in slurry, this method achieves a greater carbon dioxide sequestration capacity than slurry mineralization sequestration. Furthermore, the filling of porous materials combined with the support structure prevents ground subsidence, improves the support effect of the goaf, and simultaneously ensures the accessibility of the carbon dioxide sequestration within the cavity. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A flowchart illustrating the operation of a carbon dioxide sequestration system in an underground goaf.

[0026] Figure 2 This is a schematic diagram of the initial backfilling of a carbon dioxide sequestration system in an underground goaf.

[0027] Figure 3 A schematic diagram of secondary backfilling in a carbon dioxide sequestration system for underground goaf areas;

[0028] Figure 4 A schematic diagram of multiple backfilling in a carbon dioxide sequestration system for underground goaf areas;

[0029] Figure 5 This is a schematic diagram of the pretreatment of porous adsorption backfill material in a carbon dioxide sequestration system for underground goaf areas.

[0030] In the diagram: 100, filling module; 200, exhaust pipe; 1, V-shaped support belt; 11, V-shaped plate; 12, operating end plane; 2, buffer tank; 21, porous filler particle conveying pipeline; 22, supercritical carbon dioxide fluid conveying pipeline; 23, discharge pipeline; 231, pressure and temperature adjustment straight pipe; 24, closing valve; 3, dynamic pressure balance retractable hose; 31, backfill pipe; 32, temperature exchange and pressure boosting chamber; 4, insulation liquid fluid conveying mechanism; 5, insulation liquid pressure balance discharge port; 6, liquid return mechanism. Detailed Implementation

[0031] Please see Figures 1-5 :

[0032] In this embodiment, it includes multiple V-shaped support strips 1 that support the roof rock strata of the goaf, as well as a filling module 100 and an exhaust pipe 200 for filling the cavities separated by the V-shaped support strips 1.

[0033] In this embodiment, a simultaneous support and filling operation is adopted. The fluidity of supercritical carbon dioxide enhances the adsorption effect of porous materials. The pre-fabricated porous material is filled by the pushing action of high-pressure supercritical carbon dioxide, resulting in a final filled cavity containing porous material for support, carbon dioxide adsorbed within the pores of the porous material, and gaseous carbon dioxide filling the gaps between adjacent porous materials. This method is simple to operate, and compared to the carbon dioxide fixation in slurry, the carbon dioxide sequestration capacity is greater than that of slurry mineralization. Furthermore, the filling of porous materials combined with the support structure prevents ground subsidence and improves the support effect of the goaf.

[0034] In this embodiment, the porous adsorbed backfill material has poor flowability. Therefore, after the goaf appears, it is necessary to first use V-shaped support strip 1 for support. The V-shaped support strip 1 is triangular in shape, thus possessing both longitudinal and lateral support characteristics. This allows for the formation of a central triangular area, meeting the requirements for in-depth operations and improving operational safety. The advantage of in-depth operations is that the filling holes are also distributed longitudinally, reducing the problem of reduced backfilling effect caused by the poor flowability of the porous adsorbed backfill material. To further reduce this problem, the pipe used for backfilling can be set as a dynamic pipe, with its front end ideally able to move inside the cavity.

[0035] In this embodiment, the filling module 100 includes a buffer tank 2, a dynamic pressure-balanced contractile hose 3, a thermal insulation liquid conveying mechanism 4, a thermal insulation liquid pressure-balanced discharge port 5, and a liquid return mechanism 6. The buffer tank 2 is injected with porous adsorbent backfill material and supercritical carbon dioxide fluid through a porous filler particle conveying pipe 21 and a supercritical carbon dioxide fluid conveying pipe 22, respectively. The bottom of the buffer tank 2 is provided with a discharge pipe 23, which has a pressure and temperature adjustment straight pipe 231. The dynamic pressure-balanced contractile hose 3 is fixedly connected to the inside of the pressure and temperature adjustment straight pipe 231. The top of the pressure and temperature adjustment straight pipe 231 is provided with a backfill pipe 31. The front end of the discharge pipe 23 is provided with a closing valve 24. The top of the dynamic pressure-balanced contractile hose 3 is fixedly connected to the backfill pipe 31. The injection flow rate of the porous filler particle conveying pipe 21 and the supercritical carbon dioxide fluid conveying pipe 22 is equal to the discharge flow rate of the backfill pipe 31.

[0036] In this embodiment, the supercritical carbon dioxide fluid needs to be maintained at a pressure of 7.3 MPa and above 31°C. However, if the supercritical carbon dioxide fluid is used as the driving medium to move the porous adsorption backfill material, the open structure of the pipeline can easily cause pressure leakage, leading to the rapid conversion of supercritical carbon dioxide into gas. Therefore, a filling module 100 is set up for continuous delivery, and the supercritical carbon dioxide fluid will push the porous adsorption backfill material a certain distance. During the pushing process, the amount of carbon dioxide adsorbed by the porous adsorption backfill material is increased, and gaseous carbon dioxide storage space is formed between the circular porous adsorption backfill materials.

[0037] In this embodiment, the top pipe of the pressure and temperature adjustment straight pipe 231 is connected to the heat preservation liquid conveying mechanism 4. The pressure and temperature adjustment straight pipe 231 and the dynamic pressure balance shrinkable hose 3 form a temperature exchange and pressure boosting chamber 32. The temperature exchange and pressure boosting chamber 32 is connected to the end opening of the discharge pipe 23. The end opening of the discharge pipe 23 is provided with a heat preservation liquid pressure balance discharge port 5. The liquid discharged from the heat preservation liquid pressure balance discharge port 5 is recovered by the liquid return mechanism 6 and then heated by the heat preservation liquid conveying mechanism 4 to form a closed loop.

[0038] In this embodiment, to maintain a certain pressure within the buffer tank 2 and the discharge pipe 23, pressurization is required at the discharge end to prevent the material from flowing smoothly and to allow it to be discharged under pressure. Therefore, a dynamic pressure-balancing contractile hose 3 is provided. This hose is elastic; when the buffer tank 2 is pressureless, the temperature-balancing and pressurizing chamber 32 is in a contracted and closed state. As the pressure inside the buffer tank 2 increases until an equilibrium point is reached, the temperature-balancing and pressurizing chamber 32 becomes open, fixing the pressure inside the buffer tank 2 and achieving equilibrium. Since the pressure inside the dynamic pressure-balancing contractile hose 3 needs to be maintained at 7.3 MPa, relying solely on the hose could easily lead to pressure imbalance. Therefore, a temperature-balancing and pressurizing chamber 32 is provided between the pressure and temperature adjustment straight pipe 231 and the dynamic pressure-balancing contractile hose 3. This chamber is connected to the external heat-insulating liquid conveying mechanism 4. A warm liquid pressure-balancing discharge port 5 is provided at the end of the discharge pipe 23, which can be sealed with a spring. After the insulation liquid is injected into the insulation liquid conveying mechanism 4, the liquid fills the temperature exchange and pressure boosting chamber 32. Affected by the temperature liquid pressure balance discharge port 5, the internal pressure of the temperature exchange and pressure boosting chamber 32 increases, driving the dynamic pressure balance contraction hose 3 to contract inward. Meanwhile, the internal pressure of the buffer tank 2 acts on the dynamic pressure balance contraction hose 3, causing it to expand, thus forming a balance pressure. By adjusting this pressure, the porous adsorbent backfill and supercritical carbon dioxide fluid can be continuously introduced into the buffer tank 2. The pressure of the supercritical porous adsorbent backfill mixed fluid inside the dynamic pressure balance contraction hose 3 is maintained at 7.3 MPa, and the temperature is maintained at 31°C. This fluid state drives the movement of the porous adsorbent backfill. During the flow process, the porous adsorbent backfill and supercritical carbon dioxide fluid adsorb each other, filling the pores of the porous adsorbent backfill with carbon dioxide. When the supercritical porous adsorbed backfill material mixture reaches the backfill pipe 31, without being driven by pressure, the supercritical carbon dioxide fluid turns into gas. Under the action of gas drive or subsequent pushing, the supercritical porous adsorbed backfill material enters the cavity through the backfill pipe 31 to complete the backfilling.

[0039] In this embodiment, the exhaust pipe 200 passes through the V-shaped support belt 1 and communicates with the cavity. The other end of the exhaust pipe 200 is connected to the carbon dioxide recovery device. A pressure sensor and a gas concentration sensor are installed inside the exhaust pipe 200.

[0040] In this embodiment, as supercritical carbon dioxide vaporizes, it rapidly fills the cavity. At this point, air is expelled from the cavity. A pressure sensor installed at the exhaust pipe 200 can detect the gas pressure inside the cavity, and a gas concentration sensor can detect the amount of air remaining. In actual operation, a problem will inevitably arise: if the filling material is not completely filled, the carbon dioxide pressure inside the cavity will increase. Therefore, the exhaust pipe 200 discharges some of the carbon dioxide gas into the last-filled porous adsorption backfill storage tank, where the carbon dioxide undergoes an adsorption reaction with the porous adsorption backfill material.

[0041] In this embodiment, please refer to Figure 4 The final filling area, after being distributed by a horizontal plate, forms a triangle. At this point, the aforementioned porous adsorption backfill material is directly transported to the triangular area via a material pump or other conveying mechanism. This area utilizes the residual carbon dioxide emitted in the previous process for adsorption and final fixation.

[0042] In this embodiment, the dynamic pressure balancing retractable hose 3 is in the open discharge state, and the internal pressure of the buffer tank 2 is higher than 7.3 MPa. Since the internal pressure of the buffer tank 2 needs to be balanced through the dynamic pressure balancing retractable hose 3 during actual operation, the internal pressure of the buffer tank 2 will fluctuate during the balancing process. Therefore, keeping the internal pressure of the buffer tank 2 higher than 7.3 MPa can prevent premature vaporization.

[0043] In this embodiment, the liquid temperature inside the heat exchange and pressurization chamber 32 is higher than 31 degrees Celsius. This is mainly because the heat exchange process is also affected by the external environment and its own thermal conductivity. Therefore, keeping the liquid temperature inside the heat exchange and pressurization chamber 32 above 31 degrees Celsius ensures that the carbon dioxide remains in a fluid state.

[0044] In this embodiment, the V-shaped support belt 1 includes a V-shaped plate 11 and an operating end plane 12. When multiple V-shaped support belts 1 are fixed, the operating end plane 12 is located on the same horizontal line.

[0045] In this embodiment, some of the storage is retrievable storage. After using this method for storage, carbon dioxide stored in multiple areas can be obtained at the same horizontal level later.

[0046] Operating steps:

[0047] S1: Mix crushed gangue, fly ash, cement and water in a certain proportion to form a paste to obtain an adsorption support material;

[0048] S11: Place the paste into the V-shaped flange support mold, and take it out after it dries and hardens to obtain multiple V-shaped support strips 1. Multiple injection holes are opened at equal intervals on the inclined side of the V-shaped support strip 1. The injection holes are located at the top of the inclined side of the V-shaped support strip 1, and venting holes are opened at the top corner of the V-shaped support strip 1.

[0049] S12: Prepare the paste using a granulator or spherical mold, and remove it after drying and hardening to obtain multiple porous adsorbent backfill materials;

[0050] S2: After installing and sealing the innermost V-shaped support belt 1, push the filling module 100 into the open triangular operating face formed by the V-shaped support belt 1 and the goaf. The V-shaped support belt 1 and the goaf form two triangular filling areas for large-scale filling. The filling material is a supercritical porous adsorption backfill mixed fluid.

[0051] S3: The porous filler particle conveying pipe 21 delivers the porous adsorbent backfill material into the buffer tank 2. The supercritical carbon dioxide fluid conveying pipe 22 delivers supercritical carbon dioxide fluid through secondary pressurization, ensuring that the pressure inside the buffer tank 2 exceeds 7.3 MPa. Once a certain liquid level is reached inside the buffer tank 2, the closing valve 24 is opened. Due to the pressure inside the buffer tank 2, the supercritical porous adsorbent backfill material mixture is pressurized downwards, causing the dynamic pressure balance contraction hose 3 to open under pressure. This reduces the pressure inside the buffer tank 2, and simultaneously, the insulation liquid conveying mechanism 4 injects liquid into the buffer tank. Inside the heat exchange and pressurization chamber 32, influenced by the pressure balance discharge port 5 of the insulation liquid, the inside of the heat exchange and pressurization chamber 32 applies a reaction force to the dynamic pressure balance contraction hose 3 until the internal pressure of the dynamic pressure balance contraction hose 3 is greater than 7.3 MPa, and the dynamic pressure balance contraction hose 3 is in a connected state with the backfill pipe 31. The backfill pipe 31 is connected to the injection port of the V-shaped support belt 1. The supercritical porous adsorbent backfill material mixture reaching the backfill pipe 31 is affected by the pressure reduction. After falling into the cavity area formed by the V-shaped support belt 1, the porous adsorbent backfill material falls into the cavity area to fill it, and the supercritical carbon dioxide is converted into gas to fill the cavity.

[0052] S4: The original air in the goaf is driven out by carbon dioxide and squeezed out of the goaf through the reserved exhaust holes, and discharged through exhaust pipe 200. Exhaust pipe 200 monitors the pressure of the discharged gas and the concentration of carbon dioxide. When the pressure and concentration reach the specified threshold, exhaust pipe 200 is closed and backfill pipe 31 is withdrawn and closed.

[0053] The diameter of the porous adsorption backfill material in step S12 is smaller than the diameter of the injection hole in step S11.

[0054] Optimization: To prevent pressure leakage from the buffer tank 2, a valve can be installed at the port of the porous filler particle conveying pipe 21, and a piston-type sliding pusher mechanism is used for pushing. The main principle is that the piston inside the porous filler particle conveying pipe 21 moves backward, the valve at the end of the pipe 21 is closed, and after material is added into the space between the piston and the valve, the porous filler particle conveying pipe 21 is opened, pushing the piston into the buffer tank 2. This method can prevent pressure leakage through the discharge pipe of the porous filler particle conveying pipe 21.

[0055] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A carbon dioxide sequestration system for underground goaf areas, characterized in that: It includes multiple V-shaped support strips (1) that support the roof rock strata of the goaf, as well as filling modules (100) and exhaust pipes (200) used to fill the cavities separated by the V-shaped support strips (1). The filling module (100) includes a buffer tank (2), a dynamic pressure-balanced shrink hose (3), a thermal insulation liquid conveying mechanism (4), a thermal insulation liquid pressure-balanced discharge port (5), and a liquid return mechanism (6). The buffer tank (2) is injected with porous adsorbent backfill and supercritical carbon dioxide fluid through a porous filler particle conveying pipe (21) and a supercritical carbon dioxide fluid conveying pipe (22), respectively. The bottom of the buffer tank (2) is provided with a discharge pipe (23), which has a pressure and temperature adjustment straight pipe (231). The dynamic pressure-balanced shrink hose (3) is fixedly connected to the pressure and temperature adjustment straight pipe. Inside the pipe (231), a backfill pipe (31) is provided at the top of the pressure and temperature adjusting straight pipe (231), a closed valve (24) is provided at the front end of the discharge pipe (23), the top of the dynamic pressure balance shrinkable hose (3) is fixedly connected to the backfill pipe (31), the injection flow rate of the porous filler particle conveying pipe (21) and the supercritical carbon dioxide fluid conveying pipe (22) is equal to the discharge flow rate of the backfill pipe (31); the crushed gangue, fly ash, cement and water are mixed and stirred into a paste according to the proportion, and the paste is prepared by granulation machine or spherical mold to obtain multiple porous adsorption backfill materials; The top pipe of the pressure and temperature adjusting straight pipe (231) is connected to the heat preservation liquid fluid conveying mechanism (4). A temperature exchange and pressure boosting chamber (32) is formed between the pressure and temperature adjusting straight pipe (231) and the dynamic pressure balance shrinkable hose (3). The temperature exchange and pressure boosting chamber (32) is connected to the end opening of the discharge pipe (23). The end opening of the discharge pipe (23) is provided with the heat preservation liquid pressure balance discharge port (5). The liquid discharged from the heat preservation liquid pressure balance discharge port (5) is recovered by the liquid return mechanism (6) and then heated by the heat preservation liquid fluid conveying mechanism (4) to form a closed loop. The exhaust pipe (200) passes through the V-shaped support belt (1) and communicates with the cavity. The other end of the exhaust pipe (200) is connected to the carbon dioxide recovery device. A pressure sensor and a gas concentration sensor are provided inside the exhaust pipe (200).

2. A carbon dioxide sequestration system for underground goaf areas according to claim 1, characterized in that: When the dynamic pressure balance retractable hose (3) is in the open discharge state, the internal pressure of the buffer tank (2) is higher than 7.3 MPa.

3. A carbon dioxide sequestration system for underground goaf areas according to claim 2, characterized in that: The internal liquid temperature of the heat exchange and pressurization chamber (32) is higher than 31 degrees Celsius.

4. A carbon dioxide sequestration system for underground goaf areas according to claim 1, characterized in that: The V-shaped support belt (1) includes a V-shaped plate (11) and an operating end plane (12). When multiple V-shaped support belts (1) are fixed, the operating end plane (12) is located on the same horizontal line.

5. A method of using a carbon dioxide sequestration system for underground goaf areas according to any one of claims 1-4, characterized in that: include: S1: Mix crushed gangue, fly ash, cement and water in a certain proportion to form a paste to obtain an adsorption support material; S11: Place the paste into the V-shaped flange support mold, and take it out after it dries and hardens to obtain multiple V-shaped support strips (1). Multiple injection holes are opened at equal intervals on the inclined side of the V-shaped support strip (1). The injection holes are located at the top of the inclined side of the V-shaped support strip (1). An exhaust hole is opened at the top corner of the V-shaped support strip (1). S12: Prepare the paste using a granulator or spherical mold, and remove it after drying and hardening to obtain multiple porous adsorbent backfill materials; S2: After installing the innermost V-shaped support belt (1) and sealing it, push the filling module (100) into the open triangular operating face formed by the V-shaped support belt (1) and the goaf. The V-shaped support belt (1) and the goaf form two triangular filling areas for large-scale filling. The filling material is a supercritical porous adsorption backfill mixed fluid. S3: The porous filler particle conveying pipe (21) delivers the porous adsorbent backfill material into the buffer tank (2). The supercritical carbon dioxide fluid conveying pipe (22) pressurizes the supercritical carbon dioxide fluid through a secondary pressurization process, making the pressure inside the buffer tank (22) greater than 7.3 MPa. After a certain liquid level is reached inside the buffer tank (2), the closed valve (24) is opened. Affected by the internal pressure of the buffer tank (2), the supercritical porous adsorbent backfill material mixture is pressed downward, causing the dynamic pressure balance contraction hose (3) to open under pressure. The internal pressure of the buffer tank (2) decreases, and at the same time, the heat preservation liquid fluid conveying mechanism (4) injects... When the liquid enters the heat exchange and pressurization chamber (32), it is affected by the pressure balance discharge port (5) of the heat insulation liquid. The heat exchange and pressurization chamber (32) applies a reaction force to the dynamic pressure balance contraction hose (3) until the internal pressure of the dynamic pressure balance contraction hose (3) is greater than 7.3 MPa, and the dynamic pressure balance contraction hose (3) is in communication with the backfill pipe (31). The backfill pipe (31) is connected to the injection port of the V-shaped support belt (1). The supercritical porous adsorption backfill mixed fluid at the backfill pipe (31) is affected by the pressure reduction. After falling into the cavity area formed by the V-shaped support belt (1), the porous adsorption backfill falls into the cavity area to fill it, and the supercritical carbon dioxide is converted into gas to fill the cavity. S4: The original air in the goaf is driven out by carbon dioxide and squeezed out of the goaf through the reserved exhaust hole, and discharged through the exhaust pipe (200). The exhaust pipe (200) monitors the exhaust gas pressure and carbon dioxide concentration. When the pressure and concentration reach the specified threshold, the exhaust pipe (200) is closed and the backfill pipe (31) is withdrawn and closed.

6. The method of using a carbon dioxide sequestration system in an underground goaf according to claim 5, characterized in that: The diameter of the porous adsorption backfill material in step S12 is smaller than the diameter of the injection hole in step S11.

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