A two-way switching type underground coal gasification well upper circulation heat storage system and method

Abstract

The present application relates to the technical field of underground coal gasification, and particularly relates to a two-way switching type underground coal gasification well on-circulation heat storage system and method, which comprises a first gas reversing valve group having a first gas inlet, a first gas outlet and a first reversing interface; a first heat storage device having a first heat storage cavity and a first heat storage body arranged in the first heat storage cavity, one end of the first heat storage cavity being connected with the first reversing interface, and the other end being used for being connected with a first well in a group of underground gasification wells; a second gas reversing valve group having a second gas inlet, a second gas outlet and a second reversing interface; the heat storage device can utilize flue gas heat storage, preheat the gasification agent through the stored heat, cancel the intermediate medium and the long-distance heat transfer pipeline, and fundamentally avoid heat loss in the transmission process.

Description

Technical Field

[0001] This invention relates to the field of underground coal gasification technology, and in particular to a bidirectional switching underground coal gasification surface circulation heat storage system and method. Background Technology

[0002] Underground coal gasification technology is a technique that converts underground coal resources into combustible gas. The gasification process requires injecting a gasifying agent (such as air, oxygen-enriched air, or water vapor) underground, while simultaneously releasing high-temperature flue gas from underground. To improve gasification efficiency, the gasifying agent is usually preheated to reach a suitable reaction temperature.

[0003] Current waste heat recovery technologies from underground coal gasification have significant limitations in practical applications, restricting overall energy efficiency and environmental friendliness. Specifically, existing technologies suffer from the following problems: First, the heat utilization efficiency is low. In traditional solutions, the heat recovered by the heat storage body must first be transferred to an intermediate medium, which is then transported to the point of use through a long pipeline. This process results in significant heat loss due to heat dissipation.

[0004] Second, the environmental performance is poor. In order to reach the initial temperature required by the gasifying agent, the system often relies on an external independent heat source (such as a combustion boiler) for preheating. This process directly consumes additional fossil fuels, increasing the carbon emission burden of the process.

[0005] Third, poor fuel adaptability. When the calorific value of the produced flue gas fluctuates or is too low, traditional systems lack the ability to adjust flexibly and can usually only maintain the reaction by further increasing the preheating temperature, which exacerbates energy consumption and emission problems.

[0006] Therefore, there is an urgent need in this field for an innovative circulating thermal storage technology to overcome the shortcomings of large heat loss during transmission, reliance on external preheating, and rigid regulation, so as to achieve efficient circulation and direct utilization of energy within the system and ultimately meet the comprehensive requirements of efficient, stable and low-carbon operation.

[0007] To address this, a bidirectional switching underground coal gasification wellhead circulating heat storage system and method are proposed. Summary of the Invention

[0008] Therefore, the technical problem to be solved by this invention is: how to achieve efficient recovery and in-situ utilization of flue gas waste heat during underground coal gasification, and how to achieve adaptive adjustment of gasifying agent preheating based on temperature feedback.

[0009] The above-mentioned technical problems are solved by the following technical solution: This invention proposes a bidirectional switching underground coal gasification surface circulating heat storage system, comprising, The first gas reversing valve assembly has a first inlet, a first outlet and a first reversing interface; The first heat storage device has a first heat storage cavity and a first heat storage body disposed in the first heat storage cavity. One end of the first heat storage cavity is connected to the first reversing interface, and the other end is used to connect to the first well in the underground gasification well group. The second gas reversing valve assembly has a second inlet, a second outlet and a second reversing interface; The second heat storage device has a second heat storage cavity and a second heat storage body disposed in the second heat storage cavity. One end of the second heat storage cavity is connected to the second reversing interface, and the other end is used to connect to the second well in the underground gasification well group. In the first working state, the first air inlet is connected to the first reversing interface, and the second air outlet is connected to the second reversing interface; In the second operating state, the first air outlet is connected to the first reversing interface, and the second air inlet is connected to the second reversing interface.

[0010] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulating heat storage system of the present invention: both the first heat storage body and the second heat storage body are silicon carbide honeycomb ceramic heat storage bodies.

[0011] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulating heat storage system of the present invention: both the first heat storage cavity and the second heat storage cavity include a heat-resistant layer, a heat insulation layer and a protective layer arranged sequentially from the inside to the outside.

[0012] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulating heat storage system of the present invention: the heat-resistant layer is a heat-resistant castable layer, the insulation layer is a ceramic fiber layer, and the protective layer is a steel plate layer.

[0013] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulating heat storage system of the present invention: the first heat storage device further includes a first temperature measuring device, which is disposed in the first heat storage cavity and is used to monitor the temperature of the first heat storage body. The second heat storage device also includes a second temperature measuring device, which is disposed in the second heat storage cavity and is used to monitor the temperature of the second heat storage body.

[0014] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulating heat storage system of the present invention: the first gas reversing valve group and the second gas reversing valve group are both pneumatic reversing valves, which include a cylinder, a gate plate provided at the telescopic end of the cylinder, and a housing and a sealing element provided in the housing; The box is equipped with partitions.

[0015] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulating heat storage system of the present invention: the gate is a stainless steel gate, and the sealing element is a flexible graphite sealing element.

[0016] This invention also proposes a bidirectional switching underground coal gasification surface circulation heat storage method, characterized in that it employs the aforementioned bidirectional switching underground coal gasification surface circulation heat storage system, and the method includes: Connect the first heat storage device to the first well, and connect the second heat storage device to the second well; The first gas reversing valve group and the second gas reversing valve group are controlled to be in the first working state, so that the gasifying agent enters through the first air inlet, enters the first heat storage device through the first reversing interface, is preheated by the first heat storage device and injected into the first well, and at the same time, the flue gas discharged from the second well enters the second reversing interface through the second heat storage device and is discharged through the second air outlet. The temperature of the first heat storage device and the second heat storage device is monitored. When the preset switching conditions are met, the first gas reversing valve group and the second gas reversing valve group are controlled to switch to the second working state, so that the gasifying agent enters through the second air inlet, enters the second heat storage device through the second reversing interface, is preheated by the second heat storage device and injected into the second well. At the same time, the flue gas discharged from the first well enters the first reversing interface through the first heat storage device and is discharged through the first air outlet.

[0017] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulating heat storage method of the present invention: the preset switching conditions include: the temperature of the first heat storage device reaches a first preset temperature threshold, and the temperature of the second heat storage device is lower than a second preset temperature threshold. or, The temperature of the second heat storage device reaches the first preset temperature threshold, and the temperature of the first heat storage device is lower than the second preset temperature threshold.

[0018] In a preferred embodiment of the bidirectional switching underground coal gasification well-circulation heat storage method of the present invention: the first preset temperature threshold is 1100℃, and the second preset temperature threshold is 800℃; The vaporizing agent is at least one of air, oxygen-enriched air, or water vapor.

[0019] The beneficial effects of this invention are as follows: the heat storage device can utilize flue gas to store heat, and preheat the gasifying agent by storing the heat. It eliminates the intermediate medium and long-distance heat transmission pipelines, fundamentally avoiding heat loss during transmission, realizing the recovery and in-situ utilization of waste heat, greatly improving the overall thermal efficiency of the system, significantly enhancing the thermal energy utilization efficiency, and saving the space occupied by the equipment and the heat storage time.

[0020] In addition, the system utilizes the waste heat of its own high-temperature flue gas to preheat the gasifying agent, minimizing or even completely eliminating dependence on external independent heat sources. This directly reduces fossil fuel consumption and carbon dioxide emissions caused by external preheating, making the process more environmentally competitive.

[0021] Secondly, the design of alternating operation of the dual heat storage devices, along with the intelligent reversing logic based on temperature feedback, enables the system to adapt to fluctuations in flue gas calorific value and flow rate. By switching the roles of the injection well and the exhaust well, the underground reaction zone can be flexibly adjusted to maintain stable combustion, avoiding the preheating temperature being forced to be infinitely increased due to a decrease in calorific value, a dilemma faced by traditional systems.

[0022] Finally, the bidirectional switching mechanism enables seamless switching between heat storage and preheating modes, ensuring that the temperature and flow rate of the gasifying agent injected underground are continuous and stable without interruption. This is conducive to the smooth and continuous underground gasification reaction and ensures the operational safety of the surface system. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0024] Figure 1 A schematic diagram of the overall structure of a bidirectional switching underground coal gasification well-circulating thermal storage system is shown.

[0025] Figure 2 A schematic diagram of the first gas reversing valve group of a bidirectional switching underground coal gasification well-circulating thermal storage system is shown.

[0026] Figure 3 The diagram shows the structure of the first and second heat storage devices in a bidirectional switching underground coal gasification well-circulating heat storage system.

[0027] Figure 4 A schematic diagram of the gas reversing valve group of a bidirectional switching underground coal gasification well-circulating thermal storage system is shown, illustrating various operating modes.

[0028] In the picture: 100. First gas reversing valve assembly; 101. Cylinder; 101a. Connector; 102. Gate; 102a. Connecting rod; 103. Housing; 104. Seal; 105. Partition; 110. First air inlet; 120. First air outlet; 130. First reversing interface; 200. First heat storage device; 210. First heat storage cavity; 211. Heat-resistant layer; 212. Insulation layer; 213. Protective layer; 220. First heat storage body; 230. First temperature measuring device; 300, Second gas reversing valve assembly; 310, Second air inlet; 320, Second air outlet; 330, Second reversing interface; 400. Second heat storage device; 410. Second heat storage chamber; 420. Second heat storage body; 430. Second temperature measuring device; 500, Well No. 1; 600, Well No. 2. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0030] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0031] Reference Figures 1-4 This embodiment provides a bidirectional switching underground coal gasification surface circulation heat storage system, including, The first gas reversing valve assembly 100 has a first air inlet 110, a first air outlet 120 and a first reversing interface 130. The first heat storage device 200 has a first heat storage cavity 210 and a first heat storage body 220 disposed in the first heat storage cavity 210. One end of the first heat storage cavity 210 is connected to the first reversing interface 130, and the other end is used to connect to the first well 500 in the underground gasification well group. The second gas reversing valve assembly 300 has a second air inlet 310, a second air outlet 320, and a second reversing interface 330. The second heat storage device 400 has a second heat storage cavity 410 and a second heat storage body 420 disposed in the second heat storage cavity 410. One end of the second heat storage cavity 410 is connected to the second reversing interface 330, and the other end is used to connect to the second well 600 in the underground gasification well group. It should be noted that the first gas reversing valve group 100 and the second gas reversing valve group 300 have the same structure, and the first heat storage device 200 and the second heat storage device 400 have the same structure.

[0032] In the first working state, the first air inlet 110 is connected to the first reversing interface 130, and the second air outlet 320 is connected to the second reversing interface 330. In the second working state, the first air outlet 120 is connected to the first reversing interface 130, and the second air inlet 310 is connected to the second reversing interface 330.

[0033] As an optional embodiment: both the first heat storage body 220 and the second heat storage body 420 are silicon carbide honeycomb ceramic heat storage bodies. Silicon carbide honeycomb ceramic heat storage bodies have the characteristics of high temperature resistance of 1600-1700℃, corrosion resistance, and erosion resistance, and can adapt to the high temperature flue gas environment generated by underground coal gasification. Preferably, the first heat storage body 220 and the second heat storage body 420 can also be made of other high temperature resistant heat storage materials, such as alumina honeycomb ceramics, mullite honeycomb ceramics, etc.

[0034] As an optional embodiment: both the first heat storage cavity 210 and the second heat storage cavity 410 include a heat-resistant layer 211, a heat insulation layer 212 and a protective layer 213 arranged sequentially from the inside to the outside.

[0035] As an optional embodiment: the heat-resistant layer 211 is a heat-resistant castable layer, the insulation layer 212 is a ceramic fiber layer, and the protective layer 213 is a steel plate layer. This three-layer composite structure not only ensures the high-temperature resistance of the heat storage cavity, but also provides good insulation effect, while the outer steel plate provides structural strength and protection.

[0036] As an optional embodiment: the first heat storage device 200 further includes a first temperature measuring device 230, which is disposed in the first heat storage cavity 210 and is used to monitor the temperature of the first heat storage body 220; The second heat storage device 400 also includes a second temperature measuring device 430, which is disposed in the second heat storage cavity 410 and is used to monitor the temperature of the second heat storage body 420.

[0037] The temperature measuring device can use temperature sensors such as thermocouples to monitor the temperature status of the heat storage body in real time, providing a basis for commutation control.

[0038] As an optional embodiment: the first gas reversing valve group 100 and the second gas reversing valve group 300 are both pneumatic reversing valves. The first gas reversing valve group 100 and the second gas reversing valve group 300 have the same structure, including a cylinder 101 and a gate 102 provided at the extension end of the cylinder 101. The extension end of the cylinder 101 is provided with a connecting member 101a. The extension end of the cylinder 101 is fixedly connected to a connecting rod 102a through the connecting member 101a. The connecting rod 102a and the gate 102 are fixedly connected.

[0039] It also includes a housing 103 and a sealing element 104 disposed within the housing 103; The box 103 is equipped with a partition 105.

[0040] The partition 105 divides the interior of the housing 103 into two areas. The housing 103 is equipped with two cylinders 101 and two gates 102. The two gates 102 are used to close the spaces on both sides separated by the partition 105. The sealing element 104 can improve the sealing effect after the gates 102 are closed.

[0041] It should be noted that the first air inlet 110 and the first air outlet 120 are respectively connected to the spaces on both sides separated by the partition 105.

[0042] The cylinder 101 can also be replaced by other telescopic structures, such as hydraulic telescopic rods or electric telescopic rods.

[0043] Reference Figure 4 , Figure 4 Figure a shows a schematic diagram of the air intake using the first air intake 110. Figure 4 Figure b shows a schematic diagram of air intake using the second air intake 310, meaning that the direction of air intake or exhaust can be controlled by raising or lowering the gate 102. Figure 4 Figure c in the middle shows a schematic diagram of the two gates 102 being opened simultaneously. Figure 4 Figure d in the middle shows a schematic diagram of the two gates 102 being closed together.

[0044] As an optional embodiment: the gate 102 is a stainless steel gate, and the seal 104 is a flexible graphite seal.

[0045] Cylinder 101 is controlled by electrical components. When the cylinder rod retracts, gate 102 opens; when the cylinder rod extends, gate 102 closes. Gate 102 is made of stainless steel, which is resistant to high temperatures and corrosion. The housing 103 is a welded stainless steel housing. The partition 105 is also made of stainless steel and is used to separate the housing 103. The seal 104 is a flexible graphite seal, which can achieve stable and reliable static and dynamic sealing in extreme temperature and corrosive environments.

[0046] In the first operating state, the gasifying agent, such as air, oxygen-enriched air, or water vapor, enters the first gas reversing valve group 100 through the first air inlet 110, and then enters the first heat storage device 200 through the first reversing interface 130. In the first heat storage device 200, the gasifying agent exchanges heat with the first heat storage body 220, and is preheated to 880-1000℃ before being injected into the first well 500. Simultaneously, the high-temperature flue gas (1400-1700℃) discharged from the second well 600 enters the second heat storage device 400, exchanges heat with the second heat storage body 420, and stores the heat in the second heat storage body 420. The cooled flue gas then enters the second gas reversing valve group 300 through the second reversing interface 330 and is discharged from the second air outlet 320.

[0047] At this time, the first heat storage device 200 is in preheating mode, and the second heat storage device 400 is in heat storage mode.

[0048] When the first temperature measuring device 230 detects that the temperature of the first heat storage body 220 is below 800°C, and the second temperature measuring device 430 detects that the temperature of the second heat storage body 420 reaches 1100°C, the first gas reversing valve group 100 and the second gas reversing valve group 300 are controlled to switch to the second working state.

[0049] In the second operating state, the gasifying agent enters the second gas reversing valve group 300 through the second inlet 310, and then enters the second heat storage device 400 through the second reversing interface 330. In the second heat storage device 400, the gasifying agent exchanges heat with the second heat storage body 420, and is preheated to 880-1000℃ before being injected into the second well 600. Simultaneously, the high-temperature flue gas discharged from the first well 500 enters the first heat storage device 200, exchanges heat with the first heat storage body 220, and stores the heat in the first heat storage body 220. The cooled flue gas then enters the first gas reversing valve group 100 through the first reversing interface 130 and is discharged from the first outlet 120.

[0050] At this time, the second heat storage device 400 is in preheating mode, and the first heat storage device 200 is in heat storage mode.

[0051] Through the aforementioned periodic switching of working states, the direct recovery of waste heat from flue gas and the instant preheating of the gasifying agent are achieved, avoiding heat loss caused by intermediate medium transmission and improving the overall thermal efficiency of the system.

[0052] Reference Figures 1-4 This embodiment provides a bidirectional switching underground coal gasification surface circulation heat storage method, which employs a bidirectional switching underground coal gasification surface circulation heat storage system. The method includes: Step S1: Connect the first heat storage device 200 to the first well 500, and connect the second heat storage device 400 to the second well 600; specifically, connect the outlet of the first heat storage device 200 to the wellhead flange of the first well 500, and connect the outlet of the second heat storage device 400 to the wellhead flange of the second well 600, ensuring that the connection is sealed reliably and without leakage.

[0053] Step S2: Control the first gas reversing valve group 100 and the second gas reversing valve group 300 to be in the first working state, so that the gasifying agent enters through the first inlet 110, enters the first heat storage device 200 through the first reversing interface 130, is preheated by the first heat storage device 200 and injected into the first well 500. At the same time, the flue gas discharged from the second well 600 enters the second reversing interface 330 through the second heat storage device 400 and is discharged through the second outlet 320. In the first operating state, the first heat storage device 200 is in preheating mode, and the second heat storage device 400 is in heat storage mode. The gasifying agent is preheated to 880-1000℃ in the first heat storage device 200 and then injected into the first well 500. The high-temperature flue gas discharged from the second well 600 releases heat in the second heat storage device 400 and is then discharged.

[0054] Step S3: Monitor the temperature of the first heat storage device 200 and the second heat storage device 400. When the preset switching conditions are met, control the first gas reversing valve group 100 and the second gas reversing valve group 300 to switch to the second working state, so that the gasifying agent enters through the second air inlet 310, enters the second heat storage device 400 through the second reversing interface 330, is preheated by the second heat storage device 400 and injected into the second well 600. At the same time, the flue gas discharged from the first well 500 enters the first reversing interface 130 through the first heat storage device 200 and is discharged through the first air outlet 120.

[0055] As an optional embodiment: the preset switching conditions include: the temperature of the first heat storage device 200 reaches a first preset temperature threshold, and the temperature of the second heat storage device 400 is lower than the second preset temperature threshold; or, The temperature of the second heat storage device 400 reaches the first preset temperature threshold, while the temperature of the first heat storage device 200 is lower than the second preset temperature threshold.

[0056] As an optional embodiment: the first preset temperature threshold is 1100℃, and the second preset temperature threshold is 800℃; The vaporizing agent is at least one of air, oxygen-enriched air, or water vapor.

[0057] Specifically, the temperature of the first heat storage device 200 reaches the first preset temperature threshold of 1100℃, and the temperature of the second heat storage device 400 is lower than the second preset temperature threshold of 800℃; or, the temperature of the second heat storage device 400 reaches the first preset temperature threshold of 1100℃, and the temperature of the first heat storage device 200 is lower than the second preset temperature threshold of 800℃.

[0058] When the switching conditions are met, the first gas reversing valve group 100 and the second gas reversing valve group 300 are switched synchronously. There is no interruption in gas injection during the switching process, ensuring the continuity of the underground gasification reaction. In the second operating state, the second heat storage device 400 is in preheating mode, and the first heat storage device 200 is in heat storage mode. The gasifying agent is preheated to 880-1000℃ in the second heat storage device 400 and then injected into the second well 600. The high-temperature flue gas discharged from the first well 500 releases heat in the first heat storage device 200 and is then discharged.

[0059] Through the aforementioned periodic switching of operating states, the alternating operation of the two thermal storage devices and the dynamic interchange of the corresponding wellbore gas injection and flue gas functions are achieved. This method of dynamic well function interchange can guide and optimize the development and movement of underground combustion zones, realizing the active control of the underground gasification process.

[0060] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A bidirectional switching underground coal gasification surface circulation heat storage system, characterized in that: include, The first gas reversing valve assembly (100) has a first inlet (110), a first outlet (120) and a first reversing interface (130). The first heat storage device (200) has a first heat storage cavity (210) and a first heat storage body (220) disposed in the first heat storage cavity (210). One end of the first heat storage cavity (210) is connected to the first reversing interface (130), and the other end is used to connect to the first well (500) in the underground gasification well group. The second gas reversing valve assembly (300) has a second inlet (310), a second outlet (320), and a second reversing port (330). The second heat storage device (400) has a second heat storage cavity (410) and a second heat storage body (420) disposed in the second heat storage cavity (410). One end of the second heat storage cavity (410) is connected to the second reversing interface (330), and the other end is used to connect to the second well (600) in the underground gasification well group. In the first working state, the first air inlet (110) is connected to the first reversing interface (130), and the second air outlet (320) is connected to the second reversing interface (330); In the second working state, the first air outlet (120) is connected to the first reversing interface (130), and the second air inlet (310) is connected to the second reversing interface (330).

2. The bidirectional switching underground coal gasification surface circulation heat storage system according to claim 1, characterized in that: Both the first heat storage body (220) and the second heat storage body (420) are silicon carbide honeycomb ceramic heat storage bodies.

3. The bidirectional switching underground coal gasification surface circulation heat storage system according to claim 1 or 2, characterized in that: Both the first heat storage chamber (210) and the second heat storage chamber (410) include a heat-resistant layer (211), a heat insulation layer (212) and a protective layer (213) arranged sequentially from the inside to the outside.

4. The bidirectional switching underground coal gasification surface circulation heat storage system according to claim 3, characterized in that: The heat-resistant layer (211) is a heat-resistant castable layer, the insulation layer (212) is a ceramic fiber layer, and the protective layer (213) is a steel plate layer.

5. The bidirectional switching underground coal gasification surface circulation heat storage system according to claim 1, 2, or 4, characterized in that: The first heat storage device (200) further includes a first temperature measuring device (230), which is disposed in the first heat storage cavity (210) and is used to monitor the temperature of the first heat storage body (220); The second heat storage device (400) further includes a second temperature measuring device (430), which is disposed in the second heat storage cavity (410) and is used to monitor the temperature of the second heat storage body (420).

6. The bidirectional switching underground coal gasification surface circulation heat storage system according to claim 1, 2, or 4, characterized in that: The first gas reversing valve group (100) and the second gas reversing valve group (300) are both pneumatic reversing valves, which include a cylinder (101), a gate (102) provided at the extension end of the cylinder (101), a housing (103), and a sealing element (104) provided in the housing (103). The box (103) is equipped with a partition (105).

7. The bidirectional switching underground coal gasification surface circulation heat storage system according to claim 6, characterized in that: The gate (102) is a stainless steel gate, and the seal (104) is a flexible graphite seal.

8. A bidirectional switching underground coal gasification surface circulation heat storage method, characterized in that, The method employing the bidirectional switching underground coal gasification surface circulation thermal storage system as described in any one of claims 1 to 7 includes: Connect the first heat storage device (200) to the first well (500), and connect the second heat storage device (400) to the second well (600); The first gas reversing valve group (100) and the second gas reversing valve group (300) are controlled to be in the first working state, so that the gasifying agent enters through the first air inlet (110), enters the first heat storage device (200) through the first reversing interface (130), and is injected into the first well (500) after being preheated by the first heat storage device (200). At the same time, the flue gas discharged from the second well (600) enters the second reversing interface (330) through the second heat storage device (400) and is discharged through the second air outlet (320). The temperatures of the first heat storage device (200) and the second heat storage device (400) are monitored. When the preset switching conditions are met, the first gas reversing valve group (100) and the second gas reversing valve group (300) are controlled to switch to the second working state, so that the gasifying agent enters through the second air inlet (310), enters the second heat storage device (400) through the second reversing interface (330), and is injected into the second well (600) after being preheated by the second heat storage device (400). At the same time, the flue gas discharged from the first well (500) enters the first reversing interface (130) through the first heat storage device (200) and is discharged through the first air outlet (120).

9. The bidirectional switching underground coal gasification surface circulation heat storage method according to claim 8, characterized in that: The preset switching conditions include: the temperature of the first heat storage device (200) reaches the first preset temperature threshold, and the temperature of the second heat storage device (400) is lower than the second preset temperature threshold. or, The temperature of the second heat storage device (400) reaches the first preset temperature threshold, and the temperature of the first heat storage device (200) is lower than the second preset temperature threshold.

10. The bidirectional switching underground coal gasification surface circulation heat storage method according to claim 9, characterized in that: The first preset temperature threshold is 1100℃, and the second preset temperature threshold is 800℃; The vaporizing agent is at least one of air, oxygen-enriched air, or water vapor.

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