A combined gravity heat pipe geothermal heat extraction system, operation method, non-condensable gas control method and liquid level regulation method

Abstract

The application provides a combined gravity heat pipe geothermal heat collecting system, an operation method, a non-condensable gas control method and a liquid level adjusting method, which comprises: a geothermal heat collecting system provided with a heat collecting well, which uses a phase-changeable medium accommodated in the heat collecting well to absorb a geothermal source; a gravity heat pipe system provided with a semi-closed structure at least partially penetrating into the ground, which forms an envelope structure with the heat collecting well and constitutes a heat exchange space in which evaporation and condensation circulation can be realized; and a heat exchange system comprising a heat exchanger arranged at the upper part of the heat exchange space. The application can be applied to any type and temperature of geothermal heat source, and can adjust the non-condensable gas and the water storage capacity in the heat exchange space by only taking heat but not water, fully utilizes the geothermal resource, and makes the phase-changeable medium be at a saturation pressure suitable for the current temperature, so as to ensure that a stable heat source is provided to the heat exchange system.

Description

Technical Field

[0001] This invention belongs to the field of geothermal energy utilization technology, and particularly relates to a combined gravity heat pipe geothermal heating system, its operation method, non-condensable gas control method, and liquid level regulation method. Background Technology

[0002] Geothermal energy is a low-carbon, stable, and renewable energy source with advantages such as large reserves, wide distribution, and constant heat source temperature, offering broad application prospects. Depending on the temperature of the geothermal source, high-temperature geothermal sources are typically used for power generation, while low-temperature sources are often utilized directly as thermal energy. Based on the type of geothermal source, there are shallow geothermal energy, hydrothermal geothermal energy (groundwater), and hot dry rock. Shallow and hydrothermal geothermal sources are often utilized by directly extracting water, which causes significant damage to groundwater. The utilization of hot dry rock often employs enhanced geothermal systems, which involve injecting high-pressure water into the ground through wells, exchanging heat, and then extracting the water through another well, resulting in higher costs.

[0003] In recent years, the method of directly extracting heat from geothermal energy by manufacturing ultra-long gravity heat pipes has gained widespread attention. However, its high equipment cost remains a challenge for its widespread application. Safety, efficiency, and cost are the core issues involved in the geothermal energy extraction process. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a combined gravity heat pipe geothermal heating system, operation method, non-condensable gas control method and liquid level regulation method, which are mainly used to solve the drawbacks of the prior art, such as the large amount of energy consumed, the impact on the geological environment and the high cost of equipment, when using geothermal sources by extracting heat medium from the heating well.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a combined gravity heat pipe geothermal heating system, comprising:

[0007] A geothermal heating system is equipped with a heating well, which uses a phase change medium contained in the heating well to absorb geothermal energy.

[0008] The gravity heat pipe system has a semi-enclosed structure that extends at least partly into the ground, forming an envelope structure with the heat extraction well, thus creating a heat exchange space where evaporation and condensation can be circulated internally.

[0009] A heat exchange system, including a heat exchanger, is disposed at the upper part of the heat exchange space.

[0010] In some embodiments, a vacuum conditioning system coupled to the gravity heat pipe system is also included, which regulates the content of non-condensable gases in the heat exchange space by extracting gas.

[0011] In some embodiments, the top of the gravity heat pipe system is provided with an air extraction end for connection to the vacuum regulation system; the air extraction volume of the vacuum regulation system is adjustable and connected to the heat exchange space air passage through the air extraction end.

[0012] In some embodiments, the vacuum conditioning system includes a vacuum pump or a Roots pump.

[0013] In some embodiments, a phase change medium regulation system is further included for supplying a phase change medium to the geothermal heating system to regulate the content of the phase change medium in the heat exchange space.

[0014] In some embodiments, the gravity heat pipe system is provided with a liquid inlet; the phase change medium control system provides liquid phase change medium to the heat exchange space through the liquid inlet in an adjustable manner.

[0015] In some embodiments, the phase change medium control system includes a slurry extraction system; the slurry extraction system uses a slurry pump located at the bottom of the heating well to remove mud and rock slurry from the bottom of the heating well and to control the level of the phase change medium contained in the heating well.

[0016] In some embodiments, the gravity heat pipe system includes a sealing member that is sealed to the opening of the heat extraction well. The sealing member has a semi-closed structure and forms a heat exchange space with the heat extraction well.

[0017] In some embodiments, the heat exchanger is disposed inside the semi-enclosed structure, and the heat exchanger is provided with a refrigerant inlet and a refrigerant outlet, which are located outside the semi-enclosed structure.

[0018] In some embodiments, the phase change medium control system includes a water tank, a flow meter, and a flow regulating valve, wherein the flow regulating valve is used to regulate the amount of water stored in the heat exchange space.

[0019] In some embodiments, the gravity heat pipe system is further provided with a pressure sensor and / or a temperature sensor;

[0020] The pressure sensor is used to detect the pressure within the heat exchange space;

[0021] The temperature sensor is used to detect the temperature within the heat exchange space.

[0022] In some embodiments, the number of said temperature sensors includes at least two; one is arranged at the upper part of said gravity heat pipe system, and the other is arranged inside said gravity heat pipe system at a position more than 1m below the other said temperature sensor.

[0023] In some embodiments, an adiabatic material is further wrapped outside the sealing member, and said adiabatic material is used to reduce the heat dissipation from the heat exchange space to the outside.

[0024] In a second aspect, the present invention provides a combined gravity heat pipe geothermal heat extraction operation method, which is applied to the above combined gravity heat pipe geothermal heat extraction system, and comprises the following steps:

[0025] When the phase-changeable medium in the geothermal heat extraction system is insufficient, the phase-changeable medium is delivered into the system, so that the phase-changeable medium vaporizes in the heat extraction well after absorbing heat from the geothermal source;

[0026] Controlling the vacuum regulating system to perform an air extraction action, so as to reduce the content of non-condensable gas;

[0027] By controlling the flow rate of the refrigerant in the heat exchanger, geothermal energy is extracted through the combined gravity heat pipe geothermal heat extraction system.

[0028] In a third aspect, the present invention provides a non-condensable gas control method for a combined gravity heat pipe geothermal heat extraction system, which is applied to the above combined gravity heat pipe geothermal heat extraction system, and comprises the following steps:

[0029] Detect the steam temperature and steam pressure in the heat extraction well, determine the difference Δt between the steam temperature and the saturated steam temperature corresponding to the steam pressure, set an upper temperature difference limit C1 corresponding to the non-condensable gas content control value, and when Δt>C1, increase the output of the vacuum regulating system to reduce Δt;

[0030] Set a lower temperature difference limit C2 corresponding to the non-condensable gas content control value, and when Δt<C2, reduce the output of the vacuum regulating system.

[0031] In a fourth aspect, the present invention provides a non-condensable gas control method for a combined gravity heat pipe geothermal heat extraction system, which is applied to the above combined gravity heat pipe geothermal heat extraction system, and comprises the following steps:

[0032] According to the detected positions of different preset temperature measuring points in the heat extraction well, set an upper temperature difference limit D1 corresponding to the non-condensable gas content control value for said different preset temperature measuring points;

[0033] Detect the steam temperature at said different preset temperature measuring point positions in the heat extraction well, and calculate the steam temperature difference ΔT at said different preset temperature measuring point positions;

[0034] When ΔT>D1, increase the output of the vacuum regulating system to reduce ΔT;

[0035] setting a temperature difference lower limit D2 corresponding to the non-condensable gas content control value;

[0036] when ΔT < D2, reducing the output of the vacuum regulating system.

[0037] In a fifth aspect, the present invention provides a method for regulating the liquid level of a heat production well of a combined gravity heat pipe geothermal heat production system, which is applied to the combined gravity heat pipe geothermal heat production system described above, wherein the liquid level of the phase-changeable medium accommodated in the heat production well is set as L, and the maximum heat exchange capacity of the combined gravity heat pipe geothermal heat production system at the current liquid level is Q, the method comprises the following steps:

[0038] S1, determining the maximum heat exchange capacity Q of the combined gravity heat pipe geothermal heat production system at the liquid level L by regulating the refrigerant flow of the heat exchanger;

[0039] S2, setting a lower initial liquid level L0 of the phase-changeable medium accommodated in the heat production well, and determining the maximum heat exchange capacity Q0 of the combined gravity heat pipe geothermal heat production system at the liquid level L0 according to step S1;

[0040] S3, gradually increasing L, progressively determining Q values under different L, and establishing a relationship curve between L and Q;

[0041] S4, setting the maximum heat load Q max accommodation error limit x%;

[0042] S5, determining, according to S3, the optimal liquid level interval [L max ,Q max corresponding to Q in the interval of [(1-x%)Q x1 ,L x2 ;

[0043] S6, regulating the liquid level L of the phase-changeable medium through the phase-change medium regulating system, so that it falls within the optimal liquid level interval [L x1 ,L x2 .

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] The present invention fully utilizes the characteristics of the constant temperature heat source of geothermal energy, so that the phase-changeable medium is continuously heated and evaporated to form steam in the heat exchange space, and the vacuum regulating system and the phase-change medium regulating system are used to regulate the non-condensable gas and water storage capacity in the heat exchange space, so that the phase-changeable medium is under the saturation pressure adapted to the current temperature, and a stable heat source is ensured to be provided for the heat exchange system;

[0046] The present invention can be applied to geothermal heat sources of any type and at any temperature, fully utilizes geothermal resources by means of only extracting heat without extracting water, and greatly reduces equipment cost compared with an ultra-long gravity heat pipe.

[0047] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0048] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the overall structure of a combined gravity heat pipe geothermal heating system provided in this embodiment. Detailed Implementation

[0050] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] In the description of this invention, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may not be directly connected to the other devices but may have an intermediary device.

[0053] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0054] Reference Figure 1 In a first aspect, embodiments of the present invention provide a combined gravity heat pipe geothermal heating system, comprising:

[0055] The geothermal heating system is equipped with a heating well 3, which uses the phase change medium contained in the heating well 3 to absorb geothermal energy. The heating well 3 is dug downwards into the ground and reaches the geothermal heat storage area 2. The heating well 3 can stably store the phase change medium. The phase change medium is in a liquid state when it is input into the heating well 3. After being heated and evaporated in the heating well 3, it becomes a gaseous state.

[0056] The gravity heat pipe system has a semi-enclosed structure that extends at least partially into the ground, forming an envelope structure with the heat extraction well, thus creating a heat exchange space where evaporation and condensation cycles can be realized. The semi-enclosed structure and the heat extraction well form a heat pipe, creating a generally sealed heat exchange space with a port communicating with the outside. The phase change medium can complete a complete cycle of heating, evaporation, rising, releasing heat, condensation, and falling within the heat exchange space.

[0057] The heat exchange system includes a heat exchanger 4, which is located at the upper part of the heat exchange space.

[0058] Preferably, the heat exchange system is a power generation system, including at least one heat exchanger 4 located inside the heat extraction well 3. The heat exchanger 4 is situated in the upper part of the heat exchange space and is used to absorb heat from the phase change medium and provide a driving heat source for the power generation system, thereby converting the thermal energy of the phase change medium into electrical energy. The heat exchanger 4 absorbs heat from the vapor of the phase change medium within the heat extraction well 3, causing the refrigerant within it to evaporate, providing a driving heat source for the power generation system. The power generation system is connected to a generator to generate electricity.

[0059] It should be noted that, throughout the entire process, since the geothermal heating system only delivers heat to the outside and does not deliver any specific medium, the phase change medium will not enter the heat exchange system during the entire process, and no additional power device is required. The flow of the medium in the heat pipe is completed by utilizing the phase change process of the phase change medium and the effect of gravity.

[0060] In this embodiment, a vacuum conditioning system is also included, which is coupled to the gravity heat pipe system and adjusts the content of non-condensable gases in the heat exchange space by extracting gas.

[0061] A phase change medium regulation system is used to deliver a phase change medium to the geothermal heating system in order to regulate the content of the phase change medium in the heat exchange space.

[0062] The gravity heat pipe system has an extraction end at the top for connection to a vacuum regulation system.

[0063] The vacuum conditioning system and phase change medium control system can control the phase change medium and air. They can inject the phase change medium into the heating well 3 and extract the non-condensable gas located above the heating well 3. Since this system only extracts heat and not water, it is important to maintain the stability of the heat exchange space in the heating well 3. First, the content of non-condensable gas in the heat exchange space is adjusted by extracting gas so that the saturated steam pressure and steam temperature in the heat exchange space are matched and enter a constant temperature stable state. At this time, the phase change medium can be appropriately transported to replenish the capacity according to the changes in water storage and temperature.

[0064] Preferably, the phase change medium is water, which is heated and evaporated into water vapor in the heating well 3.

[0065] In one embodiment, the gravity heat pipe system includes a sealing member 1, which is sealed to the opening of the heat collection well 3, and the sealing member 1 and the heat collection well 3 form a heat exchange space.

[0066] The heat exchanger 4 is located inside the sealing member 1. The heat exchanger 4 is provided with a refrigerant inlet and a refrigerant outlet, which are located outside the sealing member 1.

[0067] It should be noted that there can be multiple heat exchangers 4. The heat exchangers 4 are distributed inside the sealing member 1 and located in the upper part of the heating well 3, that is, in the gas phase zone of the heating well 3. The sealing member 1 is a cap-shaped structure with a lower edge, which is fitted in the heating well 3. Its lowest end is located in the middle of the heating well 3. The water injection volume in the heating well 3 is higher than the lowest end of the sealing member 1, so that the gas phase zone where the water vapor is located is located within the space enclosed by the sealing member 1, thus preventing the water vapor from escaping.

[0068] Preferably, the heat exchanger 4 is detachably connected to the sealing component 1, forming a structural whole through the fixing component, and is directly fixed at the opening of the heat collection well 3. It is provided with a refrigerant inlet and a refrigerant outlet to the outside for transmitting refrigerant to the heat exchanger 4. The heat exchange system is connected to the refrigerant inlet and the refrigerant outlet through pipes and valves.

[0069] It should be noted that the sealing component 1 is not a complete tubular structure, but a cap-shaped structure with an opening at the bottom, which is a semi-closed structure. It can be fastened to the upper part of the heating well 3.

[0070] In one embodiment, the sealing member 1 is provided with a liquid inlet end 11 and an air extraction end 12;

[0071] The phase change medium control system provides water to the heat exchange space through the liquid inlet 11 in an adjustable manner.

[0072] The vacuum regulation system's pumping capacity is adjustable and connected to the air passage within the heat exchange space via the pumping end 12.

[0073] Optionally, the phase change medium control system includes a water tank 8, a flow meter 10, and a flow regulating valve 9. The flow regulating valve 9 is used to regulate the amount of water stored in the heat exchange space. By adjusting the opening of the flow regulating valve 9, in conjunction with the flow meter 10, the flow rate of water flowing from the water tank 8 to the heat extraction well 3 can be adjusted.

[0074] Optionally, the vacuum conditioning system includes a vacuum pump 7 or a Roots pump, and a vacuum valve.

[0075] Optionally, the sealing member 1 is also provided with a pressure sensor 5 and / or a temperature sensor 6;

[0076] Pressure sensor 5 is used to detect the pressure within the heat exchange space;

[0077] Temperature sensor 6 is used to detect the temperature within the heat exchange space.

[0078] A geothermal source temperature sensor can also be installed to detect the temperature at the bottom of the heating well 3, which is closest to the geothermal source.

[0079] Optionally, the outer side of the sealing member 1 is also covered with heat insulation material, which is used to reduce the amount of heat dissipated from the heat exchange space to the outside and prevent heat from being transferred to the outside through the sealing member 1.

[0080] Optionally, the number of temperature sensors 6 includes at least two; one is located at the upper part of the gravity heat pipe system, and the other is located at a position greater than 1m below another temperature sensor inside the gravity heat pipe system, that is, the distance between the two temperature sensors is greater than 1m.

[0081] Temperature sensors 6 are installed at preset temperature measurement points to detect the actual temperature at the corresponding locations, thereby providing data for system operation.

[0082] Optionally, the phase change medium control system includes a slurry extraction system; the slurry extraction system uses a slurry pump installed at the bottom of the heating well to remove mud and rock slurry from the bottom of the heating well and to control the level of the phase change medium contained in the heating well.

[0083] The height of the slurry pump is adjustable. On the one hand, it can descend to the mud layer to remove the mud and rock slurry from the bottom of the heating well; on the other hand, it can rise to the phase change medium layer to regulate the liquid level of the phase change medium.

[0084] Secondly, embodiments of the present invention provide a method for operating a combined gravity heat pipe geothermal energy extraction system, applied to a combined gravity heat pipe geothermal energy extraction system as described above, comprising the following steps:

[0085] A phase change medium is delivered to the geothermal heating system. The phase change medium is injected into the heating well 3, where it absorbs geothermal energy and then vaporizes in the heating well 3.

[0086] When the phase-changeable medium in the geothermal heat extraction system is insufficient, deliver the phase-changeable medium into the system, so that after the phase-changeable medium absorbs heat from the geothermal source, it vaporizes in the heat extraction well;

[0087] Control the vacuum regulation system to perform an air extraction operation, so as to reduce the content of non-condensable gas;

[0088] By controlling the flow rate of the refrigerant in the heat exchanger, geothermal energy is extracted through the combined gravity heat pipe geothermal heat extraction system.

[0089] In a third aspect, the present invention provides a non-condensable gas control method for a combined gravity heat pipe geothermal heat extraction system, which is applied to the combined gravity heat pipe geothermal heat extraction system as described above, and comprises the following steps:

[0090] Detect the steam temperature and steam pressure in the heat extraction well, and determine Δt that is the difference between the steam temperature and the saturated steam temperature corresponding to the steam pressure, set the upper temperature difference limit C1 corresponding to the non-condensable gas content control value, and when Δt > C1, increase the output of the vacuum regulation system to reduce Δt;

[0091] Set the lower temperature difference limit C2 corresponding to the non-condensable gas content control value, and when Δt < C2, reduce the output of the vacuum regulation system.

[0092] It should be noted that, in the heat exchange space, limited by the output of the vacuum regulation system, the adjustment range of the vacuum degree is limited. Therefore, the upper temperature difference limit C1 and the lower temperature difference limit C2 corresponding to the non-condensable gas content control value are determined through pre-setting, and then Δt is compared with them, so as to obtain a regulation instruction for controlling the output of the vacuum regulation system.

[0093] In a fourth aspect, the present invention provides another non-condensable gas control method for a combined gravity heat pipe geothermal heat extraction system, which is applied to the combined gravity heat pipe geothermal heat extraction system as described above, and comprises the following steps:

[0094] According to the detected positions of different preset temperature measuring points in the heat extraction well, set the upper temperature difference limit D1 corresponding to the non-condensable gas content control value for said different preset temperature measuring points;

[0095] Detect the steam temperature at said different preset temperature measuring point positions in the heat extraction well, and calculate the steam temperature difference ΔT at said different preset temperature measuring point positions;

[0096] When ΔT > D1, increase the output of the vacuum regulation system to reduce ΔT;

[0097] Set the lower temperature difference limit D2 corresponding to the non-condensable gas content control value;

[0098] When ΔT < D2, reduce the output of the vacuum regulation system.

[0099] It should be noted that, in addition to using steam temperature and steam pressure as adjustment factors, the difference ΔT between the two can be obtained by detecting specific locations through pre-set temperature measuring points. Because the heating well is relatively deep, there may be a temperature difference between the upper and lower parts of the well during the movement of the phase change medium. Therefore, when the temperature difference changes, it is compared with D1 or D2 to obtain the adjustment command for controlling the output of the vacuum regulation system. In some possible embodiments, the steam temperature and steam pressure in the heating well 3 are detected.

[0100] If the steam pressure is greater than the saturated steam pressure of the phase change medium at the corresponding steam temperature, the vacuum regulation system is controlled to perform a pumping action, and the pumping pump 7 is turned on to reduce the steam pressure.

[0101] If the steam pressure is less than the saturated steam pressure of the phase change medium at the corresponding steam temperature, the vacuum regulation system is controlled to enter the stop pumping state, and the pumping pump 7 is restored to the off state, so that the gas pressure in the heat well 3 slowly increases.

[0102] Under the action of the geothermal heating system and the temperature and pressure regulation system, room temperature water is heated into water vapor at the bottom of the heating well 3, filling the entire heat exchange space.

[0103] Heat exchanger 4 absorbs heat from the phase change medium, and the water vapor then heats the refrigerant inside the heat exchanger 4, supplying heat to the heat exchange system. After condensation, the water vapor falls back to the bottom of the heat extraction well 3 and is reheated and evaporated, forming a cycle.

[0104] Fifthly, the present invention provides a method for regulating the liquid level of a geothermal well in a combined gravity heat pipe system, applied to a combined gravity heat pipe geothermal system as described above. The method sets the liquid level of the phase-change medium contained in the well to L, and the maximum heat exchange capacity of the combined gravity heat pipe geothermal system at the current liquid level to Q. The method includes the following steps:

[0105] S1. By adjusting the refrigerant flow rate of the heat exchanger, the maximum heat exchange capacity of the combined gravity heat pipe geothermal heating system at liquid level L is determined to be Q.

[0106] S2. Set the initial liquid level L0 of the phase change medium contained in the heating well to be relatively low, and determine the maximum heat exchange Q0 of the combined gravity heat pipe geothermal heating system at the liquid level L0 according to step S1.

[0107] S3. Gradually increase L and gradually determine the Q value under different L values ​​to establish the relationship curve between L and Q;

[0108] S4, Set the maximum heat load Q max The tolerance limit is x%.

[0109] S5. Based on S3, determine Q in [(1-x%)Q max Qmax The optimal liquid level range corresponding to the interval [L] x1 ,L x2 ];

[0110] S6. The liquid level L of the phase change medium is adjusted by the phase change medium control system to ensure that it falls within the optimal liquid level range [L]. x1 ,L x2 ]Inside.

[0111] It should be noted that the maximum heat exchange capacity Q of the combined gravity heat pipe geothermal heating system needs to be matched with the refrigerant flow rate in the heat exchanger to ensure a stable heat exchange operation. Therefore, when the liquid level in the heating system changes, the corresponding heat exchange capacity Q value will also change. Thus, a relationship curve between L and Q can be established. Based on this relationship curve, the heat load range [(1-x%)Q] can be obtained. max Q max The optimal liquid level range corresponding to [L] x1 ,L x2 It is regulated by a phase change medium control system.

[0112] The following embodiments are further illustrations of the present invention, but the scope of the present invention is not limited thereto.

[0113] Combination Figure 1 This embodiment provides a combined gravity heat pipe geothermal heating system, including a geothermal heating system and a heat exchange system. The geothermal heating system includes a heating well 3, a sealing cap, and a heat exchanger 4. The sealing cap is arranged on the upper part of the heating well 3, forming a sealed space with the heating well 3. The heat exchanger 4 is arranged inside the sealing cap, and the inlet and outlet of the refrigerant in the heat exchanger 4 are arranged on the outside of the sealing cap. The heat exchanger 4 serves as a high-temperature heat absorption device to provide a heat source for the heat exchange system.

[0114] The geothermal heating system supplies water tank 8 to the heating well 3 through the phase change medium control system. First, according to the indication of flow meter 10, the flow regulating valve 9 is adjusted, and water is injected from water tank 8 into heating well 3 through liquid inlet 11. Depending on the temperature of the geothermal storage, the low-temperature water is heated into hot water or steam after contacting the geothermal storage. If it cannot be heated into steam, according to the indication of pressure sensor 5 and temperature sensor 6, the vacuum valve is adjusted, and the air pump 7 draws air from heating well 3 through air extraction end 12 to adjust the pressure in heating well 3 to the corresponding saturated evaporation pressure at the geothermal storage temperature, so that hot steam fills the entire heating well 3. The refrigerant of the heat exchange system is heated through heat exchanger 4, and after condensation, it falls back to the bottom of heating well 3, completing the geothermal heating system circulation process.

[0115] In summary, compared with the prior art, the above embodiments provide a combined gravity heat pipe geothermal heat extraction system, an operation method, a non-condensable gas control method, and a liquid level regulation method. By extracting geothermal heat without extracting water, the phase change medium is continuously heated and evaporated into steam in the heat exchange space. The non-condensable gas and water storage volume in the heat exchange space are regulated by a vacuum regulation system and a phase change medium regulation system to keep the phase change medium under a saturation pressure adapted to the current temperature, ensuring a stable heat source is provided to the heat exchange system.

[0116] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A combined gravity heat pipe geothermal heating system, characterized in that, include: A geothermal heating system is equipped with a heating well, which uses a phase change medium contained in the heating well to absorb geothermal energy. A gravity heat pipe system includes a sealing component that is sealed to the opening of the heat collection well. The sealing component has a semi-closed structure, and at least a portion of the sealing component extends into the ground to form an envelope structure with the heat collection well, thus constituting a heat exchange space in which evaporation and condensation circulation can be realized. A heat exchange system, including a heat exchanger, wherein the heat exchanger is disposed at the upper part of the heat exchange space and inside the semi-enclosed structure.

2. The combined gravity heat pipe geothermal heating system as described in claim 1, characterized in that, Also includes: A vacuum conditioning system is coupled to the gravity heat pipe system and adjusts the content of non-condensable gases in the heat exchange space by extracting gas.

3. The combined gravity heat pipe geothermal heating system as described in claim 2, characterized in that, The gravity heat pipe system has an exhaust end at the top for connection to the vacuum regulation system; the vacuum regulation system's exhaust volume is adjustable and connected to the heat exchange space air passage through the exhaust end.

4. A combined gravity heat pipe geothermal heating system as described in claim 2 or 3, characterized in that, The vacuum conditioning system includes a vacuum pump or a Roots pump.

5. A combined gravity heat pipe geothermal heating system as described in claim 1, characterized in that, Also includes: A phase change medium regulation system is used to deliver a phase change medium to the geothermal heating system in order to regulate the content of the phase change medium in the heat exchange space.

6. A combined gravity heat pipe geothermal heating system as described in claim 1 or 5, characterized in that, The gravity heat pipe system is provided with a liquid inlet; the phase change medium control system provides liquid phase change medium to the heat exchange space through the liquid inlet in an adjustable manner.

7. A combined gravity heat pipe geothermal heating system as described in claim 5, characterized in that, The phase change medium control system is equipped with a slurry extraction system; the slurry extraction system uses a slurry pump installed at the bottom of the heating well to remove mud and rock slurry from the bottom of the heating well and to control the liquid level of the phase change medium contained in the heating well.

8. A combined gravity heat pipe geothermal heating system as described in claim 1, characterized in that, The heat exchanger is provided with a refrigerant inlet and a refrigerant outlet, which are located outside the semi-enclosed structure.

9. A combined gravity heat pipe geothermal heating system as described in claim 5, characterized in that, The phase change medium control system includes a water tank, a flow meter, and a flow regulating valve, wherein the flow regulating valve is used to regulate the amount of water stored in the heat exchange space.

10. A combined gravity heat pipe geothermal heating system as described in claim 1, characterized in that, The gravity heat pipe system is also equipped with a pressure sensor and / or a temperature sensor; The pressure sensor is used to detect the pressure within the heat exchange space; The temperature sensor is used to detect the temperature within the heat exchange space.

11. A combined gravity heat pipe geothermal heating system as described in claim 10, characterized in that, The number of temperature sensors includes at least two; one is located at the upper part of the gravity heat pipe system, and the other is located more than 1m below another temperature sensor inside the gravity heat pipe system.

12. A combined gravity heat pipe geothermal heating system as described in claim 1, characterized in that, An adiabatic material is further wrapped outside the gravity heat pipe system, and the adiabatic material is used for reducing the heat dissipation from the heat exchange space to the outside.

13. A method for operating a combined gravity heat pipe geothermal heating system, applied to a combined gravity heat pipe geothermal heating system as described in any one of claims 2 to 4, characterized in that, comprising the following steps: when the phase-changeable medium in the geothermal heat extraction system is insufficient, conveying a phase-changeable medium into the system, so that the phase-changeable medium vaporizes in the heat extraction well after absorbing heat from the geothermal source; controlling a vacuum adjustment system to perform an air extraction action to reduce the content of non-condensable gas; extracting geothermal energy by the combined gravity heat pipe geothermal heat extraction system by controlling the flow rate of a refrigerant in the heat exchanger.

14. A method for controlling non-condensable gases in a combined gravity heat pipe geothermal heating system, applied to a combined gravity heat pipe geothermal heating system as described in any one of claims 2 to 4, characterized in that, comprising the following steps: detecting the steam temperature and steam pressure in the heat extraction well, determining the difference Δt between the steam temperature and the saturated steam temperature corresponding to the steam pressure, setting a temperature difference upper limit C1 corresponding to a non-condensable gas content control value, and when Δt>C1, increasing the output of the vacuum adjustment system to reduce Δt; setting a temperature difference lower limit C2 corresponding to a non-condensable gas content control value, and when Δt<C2, reducing the output of the vacuum adjustment system.

15. A method for controlling non-condensable gases in a combined gravity heat pipe geothermal heating system, applied to a combined gravity heat pipe geothermal heating system as described in any one of claims 2 to 4, characterized in that, comprising the following steps: setting, according to different preset temperature measurement point positions detected in the heat extraction well, a temperature difference upper limit D1 corresponding to the non-condensable gas content control value for the different preset temperature measurement point positions; The steam temperature at different preset temperature measuring points in the heating well is detected, and the steam temperature difference Δ at these different preset temperature measuring points is calculated. T ; When Δ T >D1, increase the output of the vacuum regulation system to reduce Δ T ; setting a temperature difference lower limit D2 corresponding to the non-condensable gas content control value; when Δ T <D2, reduce the output of the vacuum regulating system.

16. A method for regulating the liquid level in a geothermal well of a combined gravity heat pipe system, applied to a combined gravity heat pipe geothermal system as described in any one of claims 5 and 7, characterized in that, wherein the liquid level of the phase-changeable medium accommodated in the heat extraction well is set as L, and the maximum heat exchange capacity of the combined gravity heat pipe geothermal heat extraction system at the current liquid level is Q, the method comprising the following steps: S1: determining, by adjusting the flow rate of the refrigerant in the heat exchanger, the maximum heat exchange capacity Q of the combined gravity heat pipe geothermal heat extraction system at the liquid level L; S2: setting a lower initial liquid level L0 of the phase-changeable medium accommodated in the heat extraction well, and determining, according to step S1, the maximum heat exchange capacity Q0 of the combined gravity heat pipe geothermal heat extraction system at the liquid level L0; S3: gradually increasing L, sequentially determining Q values at different L, and establishing a relationship curve of L and Q; S4, Set the maximum heat load Q max tolerance limit x% S5. Based on S3, determine that Q lies in [(1-x%)Q max Q max The optimal liquid level range corresponding to the interval [L] x1 , L x2 ]; S6. The liquid level L of the phase change medium is adjusted by the phase change medium control system to ensure that it falls within the optimal liquid level range [L]. x1 , L x2 ]Inside.

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