Multi-energy collaborative closed geothermal heating system

Abstract

The invention provides a multi-energy cooperative closed geothermal heating system, which relates to the technical field of renewable energy sources and comprises a closed geothermal circulating unit, a multifunctional cooperative unit and a control unit. The geothermal circulation unit achieves working medium circulation heat absorption through the injection well, the production well and the underground heat exchange structure embedded in the rock mass. The cooperation unit is provided with an industrial waste heat loop, an electric heating heat storage loop and a heat pump unit which are connected in parallel, the primary side of a heat pump is in closed-loop connection with the production well and the injection well, and the secondary side communicates with a user heat supply pipeline. The control unit realizes two modes through path switching: in a heating mode, the heat pump unit raises the temperature of a geothermal working medium and is linked with the electric heating loop to supply heat together, and industrial waste heat supplements heat energy synchronously; and in the heat storage mode, the heat pump and the electric heating are closed, and the industrial waste heat working medium is reversely injected into the production well for geothermal heat storage. The heat taking efficiency of the closed type geothermal heating system and the heat source supply stability can be both considered.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable energy, and more particularly to a multi-energy collaborative closed-loop geothermal heating system. Background Art

[0002] As a stable and clean renewable energy, geothermal energy has important application value in the field of regional clean heating. Existing hydrothermal geothermal heating systems supply heat by directly extracting underground hot water, but there are the following significant defects: First, the uneven distribution of hot water resources limits the application fields of hydrothermal geothermal heating systems; Second, it is difficult to recharge groundwater, which is likely to cause formation settlement and environmental pollution; Third, the difference in rock permeability leads to high operation and maintenance costs of hydrothermal geothermal heating systems and makes it difficult to be applied on a large scale.

[0003] The closed-loop geothermal heating system extracts heat from deep rocks through a closed well to circulate the working fluid, which can avoid direct contact with groundwater and has significant advantages in environmental friendliness and regional adaptability. However, this technology still faces two major bottlenecks at present: On the one hand, the thermal conductivity of deep rocks is relatively low, and the heat extraction efficiency by relying solely on heat conduction is not high, making it difficult to meet the large-scale heating demand; On the other hand, continuous heat extraction easily leads to a rapid decline in the rock temperature in the near-well area, and the heating capacity of the system will decrease year by year or even fail during long-term operation. Moreover, the contradiction between the peak shaving demand under extreme weather and the continuous heat supply of the rock further restricts the popularization of the closed-loop geothermal heating system. Therefore, how to balance the high efficiency of heat extraction and the stability of heat source supply of the closed-loop geothermal heating system has become a technical problem that needs to be urgently solved by technicians in this field. Summary of the Invention

[0004] The problem solved by the present invention is how to balance the high efficiency of heat extraction and the stability of heat source supply of the closed-loop geothermal heating system.

[0005] To solve the above problems, the present invention provides a multi-energy collaborative closed-loop geothermal heating system.

[0006] The present invention provides a multi-energy collaborative closed-loop geothermal heating system, including: A closed-loop geothermal circulation unit, including an injection well, a production well, and a downhole heat exchange structure connecting the injection well and the production well. The downhole heat exchange structure is embedded in the underground rock mass, and the working fluid flows into the downhole heat exchange structure through the injection well for heat exchange and outputs heat after flowing out from the production well; A multi-functional collaborative unit, including an industrial waste heat circuit, an electric heating energy storage circuit, and a heat pump unit that are respectively arranged in parallel with the user side. The primary side inlet of the heat pump unit is connected to the production well, the primary side outlet of the heat pump unit is connected to the injection well, and the secondary side of the heat pump unit is connected to the user side for heating; A coordinated control unit for controlling the flow path of the working medium to switch between a heating mode and a heat storage mode; Wherein, in the heating mode, the heat pump unit and the electric heating heat storage loop are turned on. The working medium flows into the underground rock mass through the injection well, absorbs heat and then is output to the heat pump unit. At the same time, the industrial waste heat loop and the electric heating heat storage loop directly supply heat to the user side; In the heat storage mode, the heat pump unit and the electric heating heat storage loop are turned off, and the working medium of the industrial waste heat loop flows through the production well and then is injected into the underground rock mass for heat storage.

[0007] Optionally, the downhole heat exchange structure includes at least two horizontal wells, and each horizontal well shares one injection well and one production well.

[0008] Optionally, a fracture network area is provided in the rock mass. The fracture network area is a multi-directional network-shaped fracture group formed by hydraulic fracturing in the rock mass around the horizontal well. The fracture network area covers the radial extension area of each horizontal well and is continuously distributed along the length direction of the wellbore of each horizontal well.

[0009] Optionally, it further includes a unit circulation pump and a waste heat circulation pump. The industrial waste heat loop includes an industrial waste heat heat exchanger. The wellhead of the injection well is configured with a first injection valve and a second injection valve, and the outlet of the production well is configured with a first production valve and a second production valve; Wherein, the inlet of the unit circulation pump is connected to the primary side outlet of the heat pump unit, and the outlet of the unit circulation pump is connected to the inlet of the injection well through the first injection valve; The inlet of the second injection valve is connected to the injection well, and the outlet of the second injection valve is connected to the secondary side inlet of the industrial waste heat heat exchanger through the waste heat circulation pump; The inlet of the first production valve is connected to the production well, and the outlet of the first production valve is connected to the primary side inlet of the heat pump unit; The inlet of the second production valve is connected to the secondary side outlet of the industrial waste heat heat exchanger, and the outlet of the second production valve is connected to the production well; In the heating mode, the first injection valve and the first production valve are opened, and the second injection valve and the second production valve are closed. The working medium flows out from the primary side outlet of the heat pump unit under the drive of the unit circulation pump, flows into the injection well through the first injection valve, exchanges heat through the downhole heat exchange structure, and then flows out of the production well from the first production valve and is transported to the primary side inlet of the heat pump unit; In the heat storage mode, the second injection valve and the second production valve are opened, the first injection valve and the first production valve are closed. The working medium flows out from the secondary side outlet of the industrial waste heat exchanger in the industrial waste heat circuit and is injected into the production well. After heat storage through the downhole heat exchange structure, it flows out of the injection well through the second injection valve and is driven by the waste heat circulation pump to return to the secondary side inlet of the industrial waste heat exchanger in the industrial waste heat circuit.

[0010] Optionally, the secondary side inlet of the heat pump unit is connected to the outlet pipeline of the user side, and the secondary side outlet of the heat pump unit is connected to the inlet pipeline of the user side.

[0011] Optionally, the industrial waste heat circuit includes the waste heat circulation pump, the industrial waste heat exchanger and the waste heat discharge valve; The secondary side inlet of the industrial waste heat exchanger is connected to the outlet of the waste heat circulation pump. The secondary side of the industrial waste heat exchanger has two outlets. The first outlet of the industrial waste heat exchanger is connected to the user side through the waste heat discharge valve, and the second outlet of the industrial waste heat exchanger is connected to the production well through the second production valve; The primary side inlet of the industrial waste heat exchanger is connected to the waste heat source pipeline, and the primary side outlet of the industrial waste heat exchanger is connected to the waste heat discharge pipeline.

[0012] Optionally, the waste heat circulation pump has two inlets. The first inlet of the waste heat circulation pump is connected to the outlet pipeline of the user side through the user side control valve, and the second inlet of the waste heat circulation pump is connected to the outlet of the second injection valve; In the heat storage mode, the second production valve is opened and the waste heat discharge valve is closed. The working medium flows through the second production valve, the production well, the downhole heat exchange structure, the injection well, the second injection valve and the second inlet of the waste heat circulation pump in sequence to store waste heat in the underground formation; In the heating mode, the waste heat discharge valve is opened and the second production valve is closed. The working medium flows through the waste heat discharge valve to the user side to supply heat to the user side.

[0013] Optionally, the electric heating heat storage circuit includes a heat storage circulation pump and an electric heating water tank; The inlet of the heat storage circulation pump is connected to the outlet pipeline of the user side, and the outlet of the heat storage circulation pump is connected to the inlet of the electric heating water tank; The outlet of the electric heating water tank is connected to the inlet pipeline of the user side.

[0014] Optionally, the cooperative control unit includes: The user - side temperature sensor is arranged on the water inlet pipeline of the user side and is used for monitoring the inlet water temperature of the user side in real time and outputting a temperature signal; The heat - exchange working fluid temperature difference sensor group includes a first temperature sensor respectively arranged at the outlet section of the injection well and a second temperature sensor arranged at the outlet section of the production well, and is used for monitoring the temperature difference of the heat - exchange working fluid flowing into and out of the downhole heat - exchange structure in real time and generating a rock temperature difference signal corresponding to the temperature difference of the heat - exchange working fluid; The power grid load detection module is communicatively connected with the power grid data system and is used for obtaining power grid load information and generating a power - charge peak - valley period signal; The processing and control unit; Among them, the signal output ends of the user - side temperature sensor, the working fluid temperature difference sensor group and the power grid load detection module are all communicatively connected with the processing and control unit.

[0015] Optionally, the injection well, the production well and the downhole heat - exchange structure form a geothermal loop, and the control and processing unit is configured to execute the control logic or mode - switching logic of the electric - heating heat - storage loop control: The control logic of the electric - heating heat - storage loop is configured as follows: when the inlet water temperature of the user side is lower than a preset threshold and the power - charge peak - valley signal is in the valley - electricity period, the electric - heating heat - storage loop is started; The mode - switching logic is configured as follows: when the temperature difference of the heat - exchange working fluid is lower than a preset lower limit, the heat - storage mode is triggered, the heat - pump unit is turned off and the industrial waste - heat loop is turned on; Or, when the temperature difference of the heat - exchange working fluid returns to the normal range, the heat - pump unit is started and switched to the geothermal loop.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: the heat cycle of the working fluid is realized through the injection well, the production well and the downhole heat - exchange structure in the closed - loop geothermal cycle unit, and the downhole heat - exchange structure embedded in the rock mass can enhance the heat - exchange efficiency between the working fluid and the underground rock mass; in the multi - functional cooperation unit, the industrial waste - heat loop is connected in parallel to the user side, and the industrial waste heat is directly used for energy supply to cope with the working condition of insufficient instantaneous heat supply of the geothermal cycle unit to ensure the heating stability of the user; the electric - heating heat - storage loop can directly supply power to the user side during the low - valley period of the power grid, thereby improving the economy of the closed - loop geothermal heating system; the heat - pump unit efficiently converts the low - temperature geothermal resources into the heating temperature required by the user side through cascade temperature increase; the cooperative control unit can dynamically switch the heating and heat - storage modes according to the user - side demand and the energy working condition, and inject the working fluid flowing back from the industrial waste heat into the rock mass in the heat - storage mode to supplement the heat storage capacity of the rock mass and alleviate the heat attenuation problem caused by long - term exploitation. The present invention can optimize the multi - energy cooperation path, reduce the dependence on a single energy source, and achieve both high - efficiency heat extraction and stable heat - source supply of the closed - loop geothermal heating system. Description of the Drawings

[0017] Figure 1 This is a schematic structural diagram of a multi - energy collaborative closed - loop geothermal heating system provided by an embodiment of the present invention.

[0018] Explanation of reference numerals: 11 - Injection well; 12 - Production well; 131 - Horizontal well; 132 - Fracture network area; 141 - First injection valve; 142 - Second injection valve; 143 - First production valve; 144 - Second production valve; 15 - Unit circulation pump; 211 - Industrial waste heat heat exchanger; 212 - Waste heat circulation pump; 213 - Waste heat discharge valve; 214 - User - side control valve; 221 - Heat storage circulation pump; 222 - Electric heating water tank; 23 - Heat pump unit; 3 - User side. Detailed implementation manners

[0019] To make the above - mentioned objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0020] It should be understood that the steps recorded in the method embodiments of the present invention can be executed in different orders and / or executed in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this regard.

[0021] As used herein, the term "including" and its variants are open - ended, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "an embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions executed by these devices, modules or units or their interdependent relationships.

[0022] It should be noted that the modifiers "a" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless clearly indicated otherwise in the context, it should be understood as "one or more".

[0023] The names of the messages or information exchanged between multiple devices in the embodiments of the present invention are for illustrative purposes only and are not used to limit the scope of these messages or information.

[0024] Referring to Figure 1 , the present invention provides a multi-energy collaborative closed geothermal heating system, including: A closed geothermal circulation unit, including an injection well 11, a production well 12, and a downhole heat exchange structure connecting the injection well 11 and the production well 12. The downhole heat exchange structure is embedded in the underground rock mass A. The working fluid flows into the downhole heat exchange structure through the injection well 11 for heat exchange and outputs heat after flowing out of the production well 12.

[0025] Specifically, an injection well 11 and a production well 12 are set in the target rock formation area, and the injection well 11 and the production well 12 are connected by a high-pressure-resistant downhole heat exchange structure. Exemplarily, the well depths of the injection well 11 and the production well 12 can be greater than 2000 meters, and the downhole heat exchange structure can be a horizontal well 131, and the length of the horizontal well 131 can be greater than 1000 meters. During actual use, the working fluid (such as water or antifreeze) flows into the downhole heat exchange structure from the injection well 11, exchanges heat with the underground rock mass A, and then flows out of the production well 12 to form a closed circulation loop for underground heating.

[0026] A multi-functional collaborative unit, including an industrial waste heat circuit, an electric heating energy storage circuit, and a heat pump unit 23 that are respectively arranged in parallel with the user side 3. The primary side inlet of the heat pump unit 23 is connected to the production well 12, the primary side outlet of the heat pump unit 23 is connected to the injection well 11, and the secondary side of the heat pump unit 23 is connected to the user side 3 for heating.

[0027] Specifically, the industrial waste heat circuit is connected to the user side 3 in parallel through a pipeline and may include an industrial waste heat heat exchanger 211 to directly transfer industrial waste heat to the user side 3 for heating; the electric heating energy storage circuit may include an electric heating tank and a circulation pump, which are arranged in parallel with the user side 3. The electric heating water tank 222 is internally provided with electric heating elements, which can heat the stored water during off-peak electricity periods and supply water to the user side 3 according to the needs of the user side 3; the primary side inlet and outlet of the heat pump unit 23 are respectively connected to the production well 12 and the injection well 11, and the secondary side is connected to the user side 3. The heat pump unit 23 raises the low-temperature working fluid (such as 45°C geothermal working fluid) to the temperature required by the user side 3 (such as 65°C) by inputting electric energy.

[0028] It should be explained that the primary side refers to the circulation loop connected to the heat source, which is the source end of the heat, and the secondary side refers to the circulation loop connected to the user, which is the end point of heat transfer, that is, the primary side contacts the heat source and the secondary side contacts the user side 3.

[0029] A collaborative control unit for controlling the circulation path of the working medium to switch between a heating mode or a heat storage mode.

[0030] Wherein, in the heating mode, the heat pump unit 23 and the electric heating heat storage loop are turned on. The working medium flows into the underground rock mass A through the injection well 11, absorbs heat and then is output to the heat pump unit 23. At the same time, the industrial waste heat loop and the electric heating heat storage loop directly supply heat to the user side 3. In the heat storage mode, the heat pump unit 23 and the electric heating heat storage loop are turned off. The working medium of the industrial waste heat loop flows through the production well 12 and then is injected into the underground rock mass A for heat storage.

[0031] Specifically, in the heating mode, the working medium of the closed geothermal circulation unit flows into the downhole heat exchange structure from the injection well 11, absorbs the heat of the underground rock mass A and then flows out from the production well 12. It is heated up on the primary side of the heat pump unit 23 (such as from 45°C to 65°C). At the same time, the industrial waste heat loop directly supplies heat to the user side 3 through the industrial waste heat exchanger, and the electric heating heat storage loop uses the heat energy stored during the low valley period released by the electric heating water tank 222 to supplement the heat supply. With the cooperation of multiple energies, the secondary side of the heat pump unit 23, the industrial waste heat loop and the electric heating heat storage loop are connected in parallel to transport heat energy to the user side 3 to ensure stable heating of the user side 3.

[0032] In the heat storage mode, the heat pump unit 23 and the electric heating loop are turned off. The working medium of the industrial waste heat loop directly flows through the production well 12 and is reversely injected into the heat exchange structure under the injection well 11 to store heat through the underground rock mass A (for example, transferring the heat of the industrial waste heat working medium at 80°C to the underground rock mass A), supplementing the attenuation of the rock mass heat energy caused by long-term geothermal exploitation, and at the same time balancing the energy consumption during the peak period of the power grid.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: The heat cycle of the working fluid is realized through the injection well 11, the production well 12 and the downhole heat exchange structure in the closed geothermal cycle unit. The downhole heat exchange structure embedded in the rock mass can enhance the heat exchange efficiency between the working fluid and the underground rock mass A; in the multi-functional cooperation unit, the industrial waste heat circuit is connected in parallel to the user side 3, and the industrial waste heat is directly used for energy supply to cope with the condition of insufficient instantaneous heat supply in the geothermal cycle unit, so as to ensure the heating stability of the user heat supply; while the electric heating energy storage circuit can directly supply power to the user side 3 during the low grid valley, thereby improving the economy of the closed geothermal heating system; the heat pump unit 23 efficiently converts the low-temperature geothermal resources into the heating temperature required by the user side 3 through cascade temperature increase; the cooperative control unit can dynamically switch between the heating and energy storage modes according to the user side 3 demand and the energy condition, and inject the working fluid flowing back from the industrial waste heat into the rock mass to supplement the heat storage capacity of the rock mass in the energy storage mode, alleviating the heat attenuation problem caused by long-term exploitation. The present invention can optimize the multi-energy cooperation path, reduce the dependence on a single energy source, and achieve both the high efficiency of heat extraction and the stability of heat source supply in the closed geothermal heating system.

[0034] Optionally, the downhole heat exchange structure is a U-shaped multi-branch horizontal well group, and the downhole heat exchange structure includes at least two horizontal wells 131, and each of the horizontal wells 131 shares one injection well 11 and one production well 12.

[0035] Specifically, one injection well 11 and one production well 12 are vertically drilled in the target rock formation. The well spacing between the injection well 11 and the production well 12 is set according to the geological conditions. At least two independent horizontal wells 131 (such as 3) are drilled from the bottom of the injection well 11 to the bottom of the production well 12. The horizontal wells 131 are parallelly distributed at the same rock formation height. The spacing between adjacent horizontal wells 131 can be determined by simulation optimization (such as 50 meters). Each horizontal well 131 turns up at the bottom of the production well 12 to form a plurality of independent U-shaped channels, and the ends of all U-shaped channels converge into the production well 12; at the same time, high-temperature metal pipes can be embedded in the well walls of each horizontal well 131, and the metal pipes are encapsulated at the injection well 11 and the production well 12. The working fluid flows from the injection well 11 into each horizontal well 131, absorbs the heat of the rock mass in the horizontal well 131 and then flows to the production well 12, and finally converges to the production well 12 for output, thereby realizing the synchronous heat exchange of the multi-branch horizontal well 131. In this embodiment, the heat exchange area of the downhole heat exchange structure is enlarged by the multi-branch horizontal well 131, and the U-shaped layout can reduce the flow resistance of the working fluid, thereby improving the geothermal extraction efficiency.

[0036] Optionally, a fracture network area 132 is provided in the rock mass. The fracture network area 132 is a multi-directional network-shaped crack group formed in the rock mass around the horizontal well 131 through hydraulic fracturing. The fracture network area 132 covers the radial extension area of each horizontal well 131 and is continuously distributed along the wellbore length direction of each horizontal well.

[0037] Exemplarily, the fracture network area 132 can be distributed in a rock area with a radius of 10 meters around the horizontal well 131. In this embodiment, by forming a highly permeable fracture network area 132 around the horizontal well 131, the heat storage capacity of the rock mass can be enhanced, thereby improving the heat exchange efficiency between the rock mass and the working fluid and avoiding local heat attenuation of the underground rock mass A.

[0038] Optionally, it further includes a unit circulation pump 15 and an industrial waste heat circulation pump 212. The industrial waste heat circuit includes an industrial waste heat exchanger 211. The wellhead of the injection well 11 is configured with a first injection valve 141 and a second injection valve 142, and the outlet of the production well 12 is configured with a first production valve 143 and a second production valve 144; Wherein, the inlet of the unit circulation pump 15 is connected to the primary side outlet of the heat pump unit 23, and the outlet of the unit circulation pump 15 is connected to the inlet of the injection well 11 through the first injection valve 141; The inlet of the second injection valve 142 is connected to the injection well 11, and the outlet of the second injection valve 142 is connected to the secondary side inlet of the industrial waste heat exchanger 211 through the industrial waste heat circulation pump 212; The inlet of the first production valve 143 is connected to the production well 12, and the outlet of the first production valve 143 is connected to the primary side inlet of the heat pump unit 23; The inlet of the second production valve 144 is connected to the secondary side outlet of the industrial waste heat exchanger 211, and the outlet of the second production valve 144 is connected to the production well 12; In the heating mode, the first injection valve 141 and the first production valve 143 are opened, and the second injection valve 142 and the second production valve 144 are closed. The working fluid flows out from the primary side outlet of the heat pump unit 23 under the drive of the unit circulation pump 15, flows into the injection well 11 through the first injection valve 141, exchanges heat through the downhole heat exchange structure, and then flows out of the production well 12 through the first production valve 143 and is transported to the primary side inlet of the heat pump unit 23; In the heat storage mode, the second injection valve 142 and the second production valve 144 are opened, and the first injection valve 141 and the first production valve 143 are closed. The working fluid flows out from the secondary side outlet of the industrial waste heat exchanger 211 in the industrial waste heat circuit and is injected into the production well 12. After heat storage through the downhole heat exchange structure, it flows out of the injection well 11 through the second injection valve 142 and is driven by the industrial waste heat circulation pump 212 to flow back to the secondary side inlet of the industrial waste heat exchanger 211 in the industrial waste heat circuit.

[0039] Through the setting of the dual valve group and the reverse path of the working fluid, this embodiment can use the same underground heat exchange structure to realize geothermal extraction and industrial waste heat storage in a time-sharing manner, reduce the duplicate construction cost of the closed geothermal heating system, and improve the energy mention and utilization efficiency.

[0040] Optionally, the secondary side inlet of the heat pump unit 23 is communicated with the water outlet pipeline of the user side 3 , and the secondary side outlet of the heat pump unit 23 is communicated with the water inlet pipeline of the user side 3 .

[0041] This embodiment simplifies the connection structure between the user side 3 and the heat pump unit 23 through a direct-connection pipeline design, which can achieve efficient communication between the heat pump unit 23 and the user side 3, reduce valves and auxiliary configurations, and reduce operating energy consumption and maintenance costs.

[0042] In one embodiment, the industrial waste heat circuit includes the waste heat circulation pump 212, the industrial waste heat exchanger 211 and the waste heat discharge valve 213; The secondary side inlet of the industrial waste heat exchanger 211 is connected to the outlet of the waste heat circulation pump 212. The secondary side of the industrial waste heat exchanger 211 has two outlets. The first outlet of the industrial waste heat exchanger 211 is connected to the user side 3 through the waste heat discharge valve 213, and the second outlet of the industrial waste heat exchanger 211 is connected to the production well 12 through the second production valve 144. The primary side inlet of the industrial waste heat exchanger 211 is connected to the waste heat source pipeline, and the primary side outlet of the industrial waste heat exchanger 211 is connected to the waste heat discharge pipeline.

[0043] Specifically, in the heat storage mode, the waste heat discharge valve 213 is closed, and the industrial waste heat is stored in the underground rock mass A through the underground heat exchange structure; in the heating mode, the waste heat discharge valve 213 is opened, and the second extraction valve 144 is closed, and the industrial waste heat is directly supplied to the user side 3; or, by adjusting the opening of the waste heat discharge valve 213 and the second extraction valve 144, the industrial waste heat flows to the user side 3 and the underground heat exchange structure at the same time. This embodiment can realize the time-sharing and graded utilization of industrial waste heat through the branch design, which can be stored in the underground rock mass A or directly supplied to the user side 3, effectively improving the utilization flexibility and heating efficiency of industrial waste heat.

[0044] In one embodiment, the waste heat circulation pump 212 has two inlets, the first inlet of the waste heat circulation pump 212 is connected to the water outlet pipeline of the user side 3 through the user side control valve 214, and the second inlet of the waste heat circulation pump 212 is connected to the outlet of the second injection valve 142; In the heat storage mode, the second extraction valve 144 is opened and the waste heat discharge valve is closed, and the working medium sequentially flows through the second extraction valve 144, the production well 12, the downhole heat exchange structure, the injection well 11, the second injection valve 142, and the second inlet of the waste heat circulation pump 212; In the heating mode, the waste heat discharge valve is opened and the second extraction valve 144 is closed, and the working medium flows through the waste heat discharge valve 213 to the user side 3 to supply heat to the user side 3.

[0045] Specifically, the first inlet of the waste heat circulation pump 212 is connected to the outlet pipeline of the user side 3 through the user side control valve 214, which is used to recover the low-temperature working medium of the user side 3 in the heating mode. The second inlet is communicated with the outlet of the second injection valve 142, which is used to inject the working medium from the downhole circulation during the heat storage mode. This embodiment utilizes the dual-inlet design of the waste heat circulation pump 212 and the coordinated control of the valves to achieve the on-demand distribution of industrial waste heat for underground heat storage and heat supply to the user side 3, reduce the complexity of the closed geothermal heating system with multi-energy coordination, and improve the scheduling efficiency of industrial waste heat resources.

[0046] In one embodiment, the electric heating heat storage loop includes a heat storage circulation pump 221 and an electric heating water tank 222; The inlet of the heat storage circulation pump 221 is communicated with the outlet pipeline of the user side 3, and the outlet of the heat storage circulation pump 221 is communicated with the inlet of the electric heating water tank 222; The outlet of the electric heating water tank 222 is communicated with the inlet pipeline of the user side 3.

[0047] Furthermore, the electric heating heat storage loop can include an electric heating heat storage mode and a heat supply release mode. When the electricity price is low or the waste heat is insufficient, the heat storage circulation pump 221 can be started to pump back the working medium of the user side 3 to the electric heating water tank 222, and the built-in electric heater in the water tank heats the working medium to the set temperature for storage; when the user side 3 needs to supplement heat, the high-temperature working medium in the water tank can be injected into the inlet pipeline of the user side 3 through the heat storage circulation pump 221. Optionally, the electric heating water tank 222 is internally provided with a temperature sensor and a liquid level gauge, which can automatically start and stop the electric heater and the heat storage circulation pump 221 in combination with the demand signal of the user side 3, and preferentially reuse the valley electricity at night to complete the heat storage of the electric heating water tank 222. This embodiment can achieve the time-shifted utilization of peak-valley electric energy and the rapid replenishment of heat through an independent electric heating loop, reduce the heating cost of the user side 3, and improve the functional reliability of the closed geothermal heating system with multi-energy coordination.

[0048] In one embodiment, the coordinated control unit includes: A user side temperature sensor, which is arranged on the inlet pipeline of the user side 3 and is used to monitor the inlet water temperature of the user side 3 in real time and output a temperature signal; The heat exchange working medium temperature difference sensor group includes a first temperature sensor respectively arranged at the outlet section of the injection well 11 and a second temperature sensor at the outlet section of the production well 12, which is used to monitor the temperature difference of the heat exchange working medium flowing into and out of the downhole heat exchange structure in real time and generate a rock temperature difference signal corresponding to the temperature difference of the heat exchange working medium; The power grid load detection module is communicatively connected to the power grid data system and is used to obtain power grid load information and generate a power consumption peak-valley period signal; The processing and control unit; Among them, the signal output ends of the user-side temperature sensor, the heat exchange working medium temperature difference sensor group and the power grid load detection module are all communicatively connected to the processing and control unit.

[0049] Furthermore, the processing and control unit can receive the temperature signal, the rock temperature difference signal and the power consumption peak-valley period signal, and set a priority rule according to the three signals; it preferentially judges the temperature signal. If the water temperature on the user side is lower than the preset threshold (such as 55 °C), it triggers the electric heating heat storage loop or uses industrial waste heat for direct heat supply to the user side 3; secondly, it analyzes the rock temperature difference signal. If the temperature difference exceeds the safe range (such as greater than 15 °C), the heat storage loop of the heat storage industrial waste heat is closed to prevent the risk of heat accumulation; and the electric heating heat storage loop is preferentially started during the valley electricity period, and the underground rock mass A heat storage is preferentially released during the peak electricity period. Through multi-source data fusion and dynamic priority control in this embodiment, it can achieve precise matching of industrial waste heat storage, electric heating heat supplement and the demand of the user side 3, and take into account the power consumption economy and the heating stability of the closed geothermal heating system with multi-energy collaboration.

[0050] In one embodiment, the injection well 11, the production well 12 and the downhole heat exchange structure form a geothermal loop, and the control and processing unit is configured to execute the control logic or mode switching logic of the electric heating heat storage loop: The control logic of the electric heating heat storage loop is configured to: when the inlet water temperature of the user side 3 is lower than the preset threshold and the power consumption peak-valley signal is during the valley electricity period, start the electric heating heat storage loop; The mode switching logic is configured to: when the temperature difference of the heat exchange working medium is lower than the preset lower limit, trigger the heat storage mode, close the heat pump unit 23 and open the industrial waste heat loop; Or, when the temperature difference of the heat exchange working medium returns to the normal range, start the heat pump unit 23 and switch to the geothermal loop.

[0051] Through the dynamic switching of the heat storage / discharge strategy and the energy price linkage control in this embodiment, it can achieve the collaborative optimization of geothermal energy storage and electric heating heat supplement, and reduce the comprehensive energy consumption and operation cost of the closed geothermal heating system with multi-energy collaboration.

[0052] Although the present invention is disclosed as above, the scope of protection of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the scope of protection of the present invention.

Claims

1. A closed geothermal heating system with multi-energy collaboration, characterized in that Comprising: A closed geothermal cycle unit, including an injection well (11), a production well (12), and a downhole heat exchange structure connecting the injection well (11) and the production well (12). The downhole heat exchange structure is embedded in the underground rock mass. The working fluid flows into the downhole heat exchange structure through the injection well (11) for heat exchange, and outputs heat after flowing out from the production well (12). A multi-functional cooperation unit, including an industrial waste heat circuit, an electric heating heat storage circuit, and a heat pump unit (23) respectively arranged in parallel with the user side (3). The primary side inlet of the heat pump unit (23) is connected to the production well (12), the primary side outlet of the heat pump unit (23) is connected to the injection well (11), and the secondary side of the heat pump unit (23) is connected to the user side (3) for heating supply. A cooperation control unit, used to control the flow path of the working fluid to switch between the heating mode or the heat storage mode. Wherein, in the heating mode, the heat pump unit (23) and the electric heating heat storage circuit are turned on. The working fluid flows into the underground rock mass through the injection well (11) to absorb heat and then is output to the heat pump unit (23). At the same time, the industrial waste heat circuit and the electric heating heat storage circuit directly supply heat to the user side (3). In the heat storage mode, the heat pump unit (23) and the electric heating heat storage circuit are turned off. The working fluid of the industrial waste heat circuit flows through the production well (12) and then is injected into the underground rock mass for heat storage.

2. The multi-energy collaborative closed geothermal heating system according to claim 1, wherein The downhole heat exchange structure includes at least two horizontal wells (131), and each horizontal well (131) shares one injection well (11) and one production well (12).

3. The multi-energy collaborative closed geothermal heating system according to claim 2, characterized in that, A fracture network area (132) is provided in the rock mass. The fracture network area (132) is a multi-directional network-like crack group formed by hydraulic fracturing in the rock mass around the horizontal well (131). The fracture network area (132) covers the radial extension area of each horizontal well (131) and is continuously distributed along the length direction of each horizontal wellbore.

4. The multi-functional collaborative closed geothermal heating system according to claim 1, wherein It further includes a unit circulation pump (15) and a waste heat circulation pump (212). The industrial waste heat circuit includes an industrial waste heat heat exchanger (211). The wellhead of the injection well (11) is configured with a first injection valve (141) and a second injection valve (142), and the outlet of the production well (12) is configured with a first production valve (143) and a second production valve (144). Wherein, the inlet of the unit circulation pump (15) is connected to the primary side outlet of the heat pump unit (23), and the outlet of the unit circulation pump (15) is connected to the injection well (11) through the first injection valve (141). The inlet of the second injection valve (142) is connected to the injection well (11), and the outlet of the second injection valve (142) is connected to the secondary side inlet of the industrial waste heat heat exchanger (211) through the waste heat circulation pump (212). The inlet of the first production valve (143) is connected to the production well (12), and the outlet of the first production valve (143) is connected to the primary side inlet of the heat pump unit (23). The inlet of the second production valve (144) is connected to the secondary side outlet of the industrial waste heat exchanger (211), and the outlet of the second production valve (144) is connected to the inlet of the production well (12). In the heating mode, the first injection valve (141) and the first production valve (143) are opened, and the second injection valve (142) and the second production valve (144) are closed. The working medium flows out from the primary side outlet of the heat pump unit (23) driven by the unit circulation pump (15), flows into the injection well (11) through the first injection valve (141), exchanges heat through the downhole heat exchange structure, flows out of the production well (12) through the first production valve (143), and is transported to the primary side inlet of the heat pump unit (23). In the heat storage mode, the second injection valve (142) and the second production valve (144) are opened, and the first injection valve (141) and the first production valve (143) are closed. The working medium flows out from the secondary side outlet of the industrial waste heat exchanger (211) in the industrial waste heat circuit and is injected into the production well (12). After heat storage through the downhole heat exchange structure, it flows out of the injection well (11) through the second injection valve (142) and is driven by the waste heat circulation pump (212) to flow back to the secondary side inlet of the industrial waste heat exchanger (211) in the industrial waste heat circuit.

5. The multi-energy collaborative closed geothermal heating system according to claim 4, wherein, The secondary side inlet of the heat pump unit (23) is communicated with the outlet pipeline of the user side (3), and the secondary side outlet of the heat pump unit (23) is communicated with the inlet pipeline of the user side (3).

6. The multi-energy collaborative closed geothermal heating system according to claim 4, characterized in that, The industrial waste heat circuit includes the industrial waste heat exchanger (211), the waste heat circulation pump (212) and the waste heat discharge valve (213). The secondary side inlet of the industrial waste heat exchanger (211) is communicated with the outlet of the waste heat circulation pump (212). The secondary side of the industrial waste heat exchanger (211) has two outlets. The first outlet of the industrial waste heat exchanger (211) is connected to the user side (3) through the waste heat discharge valve (213), and the second outlet of the industrial waste heat exchanger (211) is connected to the production well (12) through the second production valve (144). The primary side inlet of the industrial waste heat exchanger (211) is communicated with the waste heat source pipeline, and the primary side outlet of the industrial waste heat exchanger (211) is connected to the waste heat discharge pipeline.

7. The multi-energy collaborative closed geothermal heating system according to claim 6, characterized in that, The waste heat circulation pump (212) has two inlets. The first inlet of the waste heat circulation pump (212) is connected to the outlet pipeline of the user side (3) through the user side control valve (214), and the second inlet of the waste heat circulation pump (212) is connected to the outlet of the second injection valve (142). In the heat storage mode, the second production valve (144) is opened and the waste heat discharge valve (213) is closed, and the working fluid sequentially flows through the second production valve (144), the production well (12), the downhole heat exchange structure, the injection well (11), the second injection valve (142) and the second inlet of the waste heat circulation pump (212) to store waste heat in the underground formation; In the heating mode, the waste heat discharge valve (213) is opened and the second production valve (144) is closed, and the working fluid flows through the waste heat discharge valve (213) to the user side (3) to supply heat to the user side (3).

8. The multi-functional collaborative closed geothermal heating system according to claim 1, characterized in that, The electric heating heat storage loop includes a heat storage circulation pump (221) and an electric heating water tank (222); The inlet of the heat storage circulation pump (221) is communicated with the outlet pipeline of the user side (3), and the outlet of the heat storage circulation pump (221) is communicated with the inlet of the electric heating water tank (222); The outlet of the electric heating water tank (222) is communicated with the inlet pipeline of the user side (3).

9. The multi-energy collaborative closed geothermal heating system according to claim 1, wherein, The collaborative control unit includes: A user-side temperature sensor is arranged on the inlet pipeline of the user side (3) for real-time monitoring of the inlet water temperature of the user side (3) and outputting a temperature signal; A heat exchange working fluid temperature difference sensor group includes a first temperature sensor respectively arranged at the outlet section of the injection well (11) and a second temperature sensor at the outlet section of the production well (12) for real-time monitoring of the temperature difference of the heat exchange working fluid flowing into and out of the downhole heat exchange structure and generating a rock temperature difference signal corresponding to the temperature difference of the heat exchange working fluid; A power grid load detection module is communicatively connected to the power grid data system for obtaining power grid load information and generating a peak-valley period signal of electricity charges; A processing and control unit; Wherein, the signal output ends of the user-side temperature sensor, the working fluid temperature difference sensor group and the power grid load detection module are all communicatively connected to the processing and control unit.

10. The multi-energy collaborative closed geothermal heating system according to claim 9, characterized in that, The injection well (11), the production well (12) and the downhole heat exchange structure form a geothermal loop, and the control and processing unit is configured to execute the control logic or mode switching logic of the electric heating heat storage loop: The control logic of the electric heating heat storage loop is configured to: when the inlet water temperature of the user side (3) is lower than a preset threshold and the electricity charge peak-valley signal is in the valley electricity period, start the electric heating heat storage loop; The mode switching logic is configured to: when the temperature difference of the heat exchange working fluid is lower than a preset lower limit, trigger the heat storage mode, close the heat pump unit (23) and open the industrial waste heat loop; Or, when the temperature difference of the heat exchange working fluid returns to the normal range, start the heat pump unit (23) and switch to the geothermal loop.

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