A three-tube convection conduction high-efficiency heat exchange geothermal well group system

Abstract

The present invention relates to the field of heat exchange geothermal well group systems, and in particular to a three-tube convection conduction type high-efficiency heat exchange geothermal well group system, comprising a heat exchange pumping well system, a heat exchange recharge well system and a surface water treatment system. The heat exchange pumping well system comprises a softened water closed heat exchange system and a geothermal water extraction system, the heat exchange recharge well system comprises a softened water closed heat exchange system and a geothermal water recharge system, and the surface water treatment system is a geothermal water treatment device. The geothermal water extraction system, the surface water treatment system and the recharge well system together constitute a geothermal water closed circulation system. Since the extraction of geothermal water is only for the purpose of establishing a heat convection mechanism, the extraction volume is small, and 100% raw water recharge is achieved, which will not cause the groundwater level to drop. The present invention utilizes the basic principles of heat conduction and heat convection to reduce the energy damage caused by excessive groundwater exploitation and the heat exchange energy loss, and has the advantages of energy saving and environmental protection, high heat exchange efficiency, and heat extraction without water extraction.

Description

Technical Field

[0001] The present invention belongs to the field of geothermal well and geothermal energy utilization technology, and particularly relates to a three-tube convection conduction

[0002] High-efficiency heat exchange geothermal well group system. Background Art

[0003] Against the backdrop of the country's dual carbon goals, geothermal energy, as one of the five available non-carbon-based clean energy sources, is receiving increasing attention for its development and utilization due to its environmentally friendly, low-carbon and renewable characteristics.

[0004] Geothermal energy is currently utilized in two main ways: one is to directly extract geothermal water and exchange it in a surface heat exchange station, using the water to heat secondary circulating water. However, the indiscriminate and high-volume extraction of geothermal water has led to a steady decline in groundwater levels. Although regulations mandate the reinjection of raw water tailwater after heat exchange, the poor porosity and permeability of thermal reservoirs in most regions have made 100% reinjection impossible. Furthermore, many experts have called for a "reinjection-based extraction" approach. However, due to the large openings in the pump chamber during geothermal well construction and the wide variety of submersible electric pumps required, subsequent utilization is difficult to avoid, including over-extraction, excessive extraction, and illegal mining. The other approach, non-interference geothermal heat exchange technology, has emerged in recent years. This technology primarily uses heat conduction between the formation and the casing. However, years of practical experience have proven its inefficiency, primarily due to poor heat conduction between the formation rocks, which prevents distant heat from reaching the surrounding formations in a timely manner.

[0005] It would be ideal if we could adopt a simple method that utilizes both heat conduction and heat convection to more efficiently absorb underground heat for application.

[0006] Chinese Patent Publication No. CN112228941A discloses a mid-deep, non-interference geothermal heating system based on loose mud-sandstone geology, comprising a return pipe and an inlet pipe, the right side of the return pipe being connected to the second high-area return pipe, which in turn is connected to the right side of the second high-area return pipe. The system is configured by arranging a return pipe, a differential pressure overflow pipe, a gauge, an inlet pipe, a differential pressure controller, a high-area return pipe, a first return pipe, a return pipe, a bypass pipe, a high-area water supply pipe, a high-area return pipe, a geothermal well return pipe, a geothermal well water supply pipe, a heat pump unit, a second return pipe, a water supply pipe, a geothermal well supply pipe, a geothermal well return pipe, a geothermal well return pipe, a geothermal well water supply pipe, a geothermal well wellhead device, and a geothermal well for coordinated use.

[0007] The current heat exchange geothermal well system has a large extraction volume, which does not meet the call of national policies and cannot achieve 100% reinjection. It does not have the advantages of energy saving and environmental protection, and does not take heat without taking water. Summary of the Invention

[0008] To this end, the purpose of the present invention is to provide a three-tube convection conduction high-efficiency heat exchange geothermal well group system, which has the advantages of environmental protection, low carbon, high heat exchange rate, and heat extraction without water.

[0009] To achieve the above objectives, the present invention provides a three-tube convection conduction high-efficiency heat exchange geothermal well group system, comprising:

[0010] The first heat recovery system, including the heat exchange pumping well system, the heat exchange reinjection well system and the surface water treatment system, serves as the main operating system of the high-efficiency heat exchange geothermal well group system. It can extract geothermal water from the ground, transfer the heat of the geothermal water to cold softened water, and reinject the geothermal water after the energy transfer is completed into the ground;

[0011] a second heat recovery system, comprising the first heat recovery system and a geothermal water extraction diversion system, for supplementing heat exchange when the first heat recovery system is insufficiently heated, the geothermal water extraction diversion system being arranged between the geothermal water extraction outlet and the surface water treatment system;

[0012] A third heat recovery system, comprising the first heat recovery system and a geothermal water recirculation system, is configured to perform heat exchange again when the geothermal water recirculated in the first heat recovery system is too hot. The geothermal water recirculation system is disposed between the outlet of the heat exchange recirculation well system and the outlet of the extracted geothermal water.

[0013] The temperature of geothermal water that has not undergone heat exchange is detected to determine whether to start the first heat regeneration system, and the pumping speed of the first submersible electric pump in the first heat regeneration system when it is turned on is determined. By detecting the temperature of geothermal water that has passed through the surface water treatment system, it is determined whether to adjust the pumping speed of the first submersible electric pump and whether to start the second heat regeneration system. By detecting the temperature of geothermal water that is about to flow out of the heat exchange recharge well system, it is determined whether to adjust the pumping speed of the first submersible electric pump and whether to start the third heat regeneration system.

[0014] Furthermore, it also includes a central control module, which is connected to the first heat recovery system, the second heat recovery system, and the third heat recovery system respectively, for adjusting the working status of each component.

[0015] The heat exchange pumping well system of the first heat recovery system includes:

[0016] An initial temperature sensing module, which is connected to the central control module and is disposed at the bottom of the first heat recovery system, serves as a temperature detection device for the heat exchange pumping well system and is used to detect the temperature of the extracted geothermal water;

[0017] a first submersible electric pump, connected to the central control module, for pumping geothermal water to the first heat recovery system;

[0018] a first heat exchange tube set, which is a tube assembly that transfers heat from geothermal water to cold softened water;

[0019] The heat exchange tube set includes:

[0020] An open casing, serving as the well wall pipe of the heat exchange pumping well, provides a channel for geothermal water to flow from the production layer to the ground;

[0021] The double-open casing is used as the wall pipe of the heat exchange pumping well to provide a passage for the geothermal water to flow from the production layer to the ground.

[0022] The diameter of the first open casing is larger than that of the second open casing, and a larger heat exchange cavity is formed by the first open casing, which ensures the retention and sufficient heat exchange of geothermal water.

[0023] Heat exchange pipes are placed in the heat exchange pumping well and are used to connect the cold softened water inflow pipeline;

[0024] An inner tube, placed inside the heat exchange tube, for connecting to a hot softened water outflow pipeline;

[0025] A thermal insulation coating is used to reduce heat dissipation of the system, and the thermal insulation coating is evenly applied to the upper low-temperature sections of the first-open casing and the second-open casing;

[0026] cementing section, used to stabilize the system;

[0027] A pipe plug, an externally threaded pipe fitting used to plug the internal thread at the end of the pipe, and is arranged at the bottom of the heat exchange tube;

[0028] The water filter pipe, as the well wall pipe of the heat exchange pumping well, can take in geothermal water and filter the soil or rock particles around the well wall to support and protect the well wall;

[0029] A heat storage layer is placed around the double-open casing and the water filter pipe, and is used to keep the hot water in the pipeline warm;

[0030] A specially made water stop is placed on the upper part of the heat reservoir;

[0031] The first submersible electric pump is placed in the annular space between the open casing and the heat exchange tube.

[0032] Furthermore, the geothermal water extraction diversion system of the second heat recovery system includes:

[0033] a second submersible electric pump, connected to the central control module, for pumping geothermal water to the second heat recovery system;

[0034] A diversion pipeline is used to provide a channel for the extracted geothermal water to flow to the surface water treatment system;

[0035] The heat exchange reinjection well system includes:

[0036] A second heat exchange tube set, the components of which are the same as those of the first heat exchange tube set;

[0037] An inlet temperature sensing module, which is connected to the central control module and is disposed at the inlet of the heat exchange recharge well system, serves as a temperature detection device of the heat exchange recharge well system, and is used to detect the temperature of the geothermal water flowing into the heat exchange recharge well system;

[0038] An outlet temperature sensing module, which is connected to the central control module and is disposed at the outlet of the heat exchange recharge well system, serves as a temperature detection device of the heat exchange recharge well system, and is used to detect the temperature of geothermal water flowing out of the heat exchange recharge well system;

[0039] The second submersible electric pump is placed between the geothermal water outlet and the surface water treatment system;

[0040] The geothermal water recirculation system of the third heat recovery system includes:

[0041] A third submersible electric pump is connected to the central control module and is placed between the outlet of the heat exchange recharge well system and the outlet of the extracted geothermal water, and is used to return the geothermal water to the third heat recovery system;

[0042] The return pipe is used to provide a channel for the reinjected geothermal water to flow back to the outlet of the extracted geothermal water.

[0043] Furthermore, the entire three-tube convection conduction high-efficiency heat exchange geothermal well group system is divided into two closed water circulation systems, one is a geothermal water closed circulation system, and the other is a softened water heat exchange circulation system.

[0044] Furthermore, the initial temperature sensing module detects the geothermal water temperature to determine whether the current geothermal water meets the minimum temperature requirement for system operation, and determines whether to adjust the operating speed of the first submersible electric pump in the running system based on the detection result.

[0045] Furthermore, the first submersible electric pump is provided with an operating speed interval. When the adjusted theoretical operating speed exceeds the operating speed interval, the interval endpoint value is used as the actual operating speed of the first submersible electric pump.

[0046] Furthermore, the inlet temperature sensing module detects the temperature of the geothermal water that is about to flow into the heat exchange reinjection well system to determine whether the temperature of the reinjected geothermal water flowing into the heat exchange reinjection well system meets the system heat exchange temperature. If it does not meet the requirements, the pump speed of the first submersible electric pump is adjusted. If the pump speed of the first submersible electric pump reaches the maximum interval endpoint value, the geothermal water extraction diversion system is started to enable the second heat recovery system to start working.

[0047] Furthermore, when the second heat regeneration system is started, the central control module is provided with an operation evaluation value of the second submersible electric pump to determine whether the initial operation speed of the second submersible electric pump meets the heat exchange requirement of the heat exchange recharge well system. When the actual operation value is greater than the operation evaluation value, the central control module adjusts the pump speed of the second submersible pump.

[0048] Furthermore, the outlet temperature sensing module detects the temperature of the geothermal water about to flow out of the heat exchange recharge well system to determine whether the temperature of the recharged geothermal water flowing out of the heat exchange recharge well system meets the system recharge temperature. If it does not meet the requirements, the pump speed of the first submersible electric pump is adjusted. If the pump speed of the first submersible electric pump reaches the minimum interval endpoint value, the recharged geothermal water return system is started, and the third heat recovery system starts to work.

[0049] Furthermore, when the third heat regeneration system is started, the central control module is provided with an operation evaluation value of the third submersible electric pump to determine whether the initial operation speed of the third submersible electric pump meets the reinjection requirements of the heat exchange reinjection well system. When the actual operation value is greater than the operation evaluation value, the central control module adjusts the pumping speed of the third submersible pump.

[0050] Compared with the prior art, the present invention has the advantages of energy conservation and environmental protection, high heat exchange efficiency, and heat extraction without water extraction by utilizing the basic principles of heat conduction and heat convection. The entire system is divided into two closed water circulation systems: one is a geothermal water closed circulation system, in which a small amount of geothermal water is brought out from the wellbore of the heat exchange pumping well system by a submersible electric pump. The geothermal water continuously transfers heat to the heat exchange pipes during its rise. At the same time, the flow of geothermal water can more quickly carry heat from distant areas in the formation. The temperature of the geothermal tail water after heat exchange is still high, and the heat can be further transferred to the heat exchange pipes of the heat exchange re-injection well system, and finally re-injected into the formation, forming a closed convection circulation system. Since the extraction of geothermal water is only to establish a heat convection mechanism, the extraction volume is very small, so 100% raw water re-injection can be achieved without causing the groundwater level to drop. The other is a softened water heat exchange circulation system, in which softened water is fed into the heat exchange pipes through the annulus between the heat exchange pipes and the inner pipe. The heat exchange pipes exchange heat with both the flowing geothermal water and the formation, thereby improving the heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a structural diagram of a three-tube convection conduction high-efficiency heat exchange geothermal well group system;

[0052] Figure 2 It is a structural diagram of the heat exchange pumping well system;

[0053] Figure 3 It is a structural diagram of the heat exchange reinjection well system.

[0054] The figure includes: a heat exchange pumping well system 1, a heat exchange recharge well system 2, a surface water treatment system 3, a geothermal water extraction diversion system 4, a geothermal water recharge return system 5, an open casing 101, a double open casing 102, a heat exchange tube 103, an inner tube 104, a thermal insulation coating 105, a cementing section 106, a pipe plug 107, a first submersible electric pump 108, a water filter tube 109, a thermal reservoir 110, a special water stop 111, an initial temperature sensing module 112, an open casing 201, a double open casing 202, a heat exchange tube 203, an inner tube 204, a thermal insulation coating 205, a cementing section 206, a pipe plug 207, a water filter tube 209, a special water stop 210, an inlet temperature sensing module 213, an outlet temperature sensing module 214, a second submersible electric pump 41, a diversion pipeline 42, a third submersible electric pump 51, and a return pipeline 52. DETAILED DESCRIPTION

[0055] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0056] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0057] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0058] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0059] See also Figure 1-Figure 3 As shown, Figure 1 This is a structural diagram of a three-tube convection conduction high-efficiency heat exchange geothermal well group system; Figure 2 It is a structural diagram of the heat exchange pumping well system; Figure 3 It is a structural diagram of the heat exchange reinjection well system.

[0060] The present invention provides a three-tube convection conduction high-efficiency heat exchange geothermal well group system, comprising:

[0061] The first heat recovery system, including the heat exchange pumping well system 1, the heat exchange reinjection well system 2 and the surface water treatment system 3, serves as the main operating system of the high-efficiency heat exchange geothermal well group system. It can extract geothermal water from the ground, transfer the heat of the geothermal water to cold softened water, and reinject the geothermal water after the energy transfer is completed into the ground;

[0062] The second heat recovery system includes the first heat recovery system and the extraction geothermal water diversion system 4, which is used to supplement the heat exchange when the heat exchange of the first heat recovery system is insufficient. The extraction geothermal water diversion system 4 is arranged between the extraction geothermal water outlet and the surface water treatment system 3;

[0063] The third heat recovery system includes the first heat recovery system and the geothermal water recirculation system 5, which is used to perform heat exchange again when the geothermal water recirculated in the first heat recovery system is too hot. The geothermal water recirculation system 5 is arranged between the outlet of the heat exchange recirculation well system 2 and the outlet of the extracted geothermal water;

[0064] When the geothermal well group system is working, only using the first heat recovery system cannot fully exchange the heat in the geothermal water, resulting in energy waste. By adding a geothermal water extraction diversion system and a geothermal water reinjection reflux system on the basis of the first heat recovery system, the second heat recovery system and the third heat recovery system can assist the first heat recovery system to jointly complete efficient heat exchange, eliminate the situation where the system units work ineffectively, and achieve the most economical operation effect.

[0065] Specifically, it also includes a central control module, which is connected to the first heat regeneration system, the second heat regeneration system, and the third heat regeneration system respectively, for adjusting the working state of each component;

[0066] The heat exchange pumping well system of the first heat recovery system includes:

[0067] An open casing 101, as the well wall pipe of the heat exchange pumping well, provides water for the geothermal water to flow from the production layer to the ground.

[0068] Supply channel;

[0069] The double-open casing 102 is used as the wall pipe of the heat exchange pumping well to provide heat for the ground water to flow from the production layer to the ground.

[0070] Supply channel;

[0071] The diameter of the single-open casing 101 is larger than that of the double-open casing 102 . A larger heat exchange cavity is formed by the single-open casing 101 , thereby ensuring the retention and sufficient heat exchange of geothermal water.

[0072] The heat exchange pipe 103 is placed in the heat exchange pumping well and is used to connect the cold softened water inflow pipeline;

[0073] The inner tube 104 is placed inside the heat exchange tube 103 and is used to connect to the hot softened water outflow pipeline;

[0074] Thermal insulation coating 105, used to reduce system heat dissipation;

[0075] Cementing section 106, used to stabilize the system;

[0076] The pipe plug 107 is used to plug the external threaded pipe fitting with internal thread at the end of the pipe, and is installed on the heat exchange pipe 103.

[0077] bottom;

[0078] A first submersible electric pump 108 , connected to the central control module and placed in the annular space between the open casing 101 and the heat exchange tube 103 , is used to pump geothermal water to the first heat recovery system;

[0079] The water filter pipe 109, as the well wall pipe of the heat exchange pumping well, can take in geothermal water and filter the soil or rock particles around the well wall to support and protect the well wall;

[0080] The heat reservoir 110 is placed around the double-open casing 102 and the water filter pipe 109 and is used to

[0081] Geothermal water insulation;

[0082] A specially made water stop 111 is placed on the upper part of the heat reservoir 110;

[0083] The initial temperature sensing module 112 is connected to the central control module and is disposed at the bottom of the first heat recovery system. It serves as a temperature detection device of the heat exchange pumping well system 1 and is used to detect the temperature of the extracted geothermal water.

[0084] By using the first submersible electric pump to drive the geothermal water flow, the geothermal water flows from the heat reservoir through the filter pipe.

[0085] It flows out continuously, transferring heat to the heat exchange tubes during the upward flow; the cold softened water in the heat exchange tubes and the inner tube annulus absorbs heat from the rock formations and from the flowing geothermal water during the downward movement, and then becomes hot softened water and flows out of the inner tube, both of which transfer energy and improve the heat exchange efficiency.

[0086] The heat exchange pumping well system consists of three sets of pipes: the outermost casing, the heat exchange tube, and the inner tube. The heat exchange tube is located adjacent to the outer casing on one side. The outermost casing has a larger diameter, increasing the direct contact area with the rock formation and enhancing heat transfer capacity. Furthermore, the establishment of two circulation systems not only utilizes heat conducted from the rock formation but also further utilizes heat generated by convection from the geothermal water, making heat exchange more efficient.

[0087] Specifically, the heat exchange reinjection well system 2 includes:

[0088] An open casing 201 is used as the well wall pipe of the heat exchange reinjection well to provide water for geothermal water to flow from the ground to the production layer.

[0089] Supply channel;

[0090] The double-open casing 202 is used as the wall pipe of the heat exchange reinjection well to provide geothermal water from the ground to the production layer.

[0091] Supply channel;

[0092] The diameter of the single-open casing 201 is larger than that of the double-open casing 202 . A larger heat exchange cavity is formed by the single-open casing 201 , thereby ensuring the retention and sufficient heat exchange of geothermal water.

[0093] The heat exchange pipe 203 is placed in the heat exchange recharge well and is used to connect the cold softened water inflow pipeline;

[0094] The inner tube 204 is placed inside the heat exchange tube 203 and is used to connect to the hot softened water outflow pipeline;

[0095] Thermal insulation coating 205, used to reduce system heat dissipation;

[0096] Cementing section 206, used to stabilize the system;

[0097] The pipe plug 207 is used to plug the external threaded pipe fitting with the internal thread at the end of the pipe, and is arranged between the heat exchange pipe 203 and the pipe.

[0098] Bottom thread connection;

[0099] The water filter pipe 209, as the well wall pipe of the heat exchange recharge well, can recharge the geothermal water and filter the soil or rock particles around the well wall to support and protect the well wall;

[0100] The heat reservoir 210 is placed around the two-open casing 202 and the water filter pipe 209 to

[0101] Geothermal water insulation;

[0102] The inlet temperature sensing module 213 is connected to the central control module and is provided at the inlet of the heat exchange reinjection well system 2. It serves as a temperature detection device of the heat exchange reinjection well system 2 and is used to detect the temperature of the geothermal water flowing into the heat exchange reinjection well system 2.

[0103] The outlet temperature sensing module 214 is connected to the central control module and is provided at the outlet of the heat exchange reinjection well system 2. It serves as a temperature detection device of the heat exchange reinjection well system 2 and is used to detect the temperature of the geothermal water flowing out of the heat exchange reinjection well system 2.

[0104] By adopting the above technical solution, the geothermal tailwater temperature remains high, and further heat is exchanged through the heat exchange pipe, making the heat exchange more complete. In addition, the heat exchange pumping well system and the heat exchange re-injection well system can also be interchanged.

[0105] The second heat recovery system's geothermal water extraction diversion system 4 includes:

[0106] A second submersible electric pump 41 is connected to the central control module and is placed between the geothermal water outlet and the surface water treatment system to provide energy for the extracted geothermal water to flow to the surface water treatment system 3;

[0107] A diversion pipe 42 is used to provide a channel for the extracted geothermal water to flow to the surface water treatment system 3;

[0108] The geothermal water recirculation system 5 of the third heat regeneration system includes:

[0109] A third submersible electric pump 51, which is connected to the central control module and is placed between the outlet of the heat exchange recharge well system and the outlet of the extracted geothermal water, to provide energy for the returned geothermal water to flow to the outlet of the extracted geothermal water;

[0110] The return pipe 52 is used to provide a channel for the reinjected geothermal water to flow back to the outlet of the extracted geothermal water;

[0111] Specifically, the central control module is provided with a minimum geothermal water temperature C0 for equipment operation. When the initial temperature sensing module 112 detects that the temperature is higher than C0, the first submersible electric pump 108 operates at an initial speed V, driving geothermal water into an open casing 101. The initial temperature sensing module 112 detects the temperature of the inflowing geothermal water and obtains the geothermal water temperature C. The central control module is provided with a first geothermal water temperature evaluation value Cmin and a second geothermal water temperature evaluation value Cmax.

[0112] If Cmin ≤ C ≤ Cmax, the central control module does not adjust the speed of the first submersible electric pump 108;

[0113] C<Cmin, the central control module accelerates and adjusts the first submersible electric pump 108. After adjustment, the speed of the first submersible electric pump 108 is V', and V'=V+(Cmin-C)×E1, where E1 is the acceleration adjustment parameter of the first submersible electric pump 108 for the geothermal water temperature.

[0114] C>Cmax, the central control module decelerates the first submersible electric pump 108. After adjustment, the speed of the first submersible electric pump 108 is V", and V"=V-(Cmax-C)×E2, where E2 is the deceleration adjustment parameter of the first submersible electric pump 108 affected by the geothermal water temperature.

[0115] The temperature measured by the initial temperature sensing module is compared with the standard temperature range to control the pumping speed of the first submersible electric pump. When the measured temperature is higher than the standard temperature range, the pumping speed is slowed down so that the geothermal water can be fully exchanged and the heat exchange efficiency is improved. When the measured temperature is lower than the standard temperature range, the pumping speed is accelerated to avoid wasting the working efficiency of the unit system and prevent heat loss, which is more environmentally friendly and energy-saving.

[0116] The central control module is provided with a maximum operating pump speed Vmax of the first submersible electric pump and a minimum operating pump speed Vmin of the first submersible electric pump;

[0117] If V'>Vmax, the speed of the first submersible electric pump is adjusted to the maximum operating pump speed Vmax of the first submersible electric pump;

[0118] If V'<Vmin, the speed of the first submersible electric pump is adjusted to Vmin.

[0119] Specifically, the inlet temperature sensing module 213 detects the temperature of the geothermal water about to flow into the heat exchange recharge well system 2, and obtains the geothermal water temperature A about to flow into the heat exchange recharge well system 2. The central control module is provided with a second heat recharge system start evaluation temperature Amin.

[0120] When A≥Amin, the temperature of the geothermal water flowing into the heat exchange recharge well system 2 meets the system heat exchange temperature, and the central control module does not adjust the first heat regeneration system or open the geothermal water extraction diversion system 4 due to the water temperature flowing into the heat exchange recharge well system;

[0121] When A<Amin, if the pumping speed of the first submersible electric pump 108 is less than the maximum operating pumping speed Vmax of the first submersible electric pump, the pumping speed of the first submersible electric pump 108 is adjusted, and the adjusted pumping speed of the first submersible electric pump is set to V11, V11=V1+(Amin-A)×E3, wherein V1 is one of V, V', and V", and E3 is the acceleration adjustment parameter of the first submersible electric pump for the geothermal water temperature that is about to flow into the heat exchange reinjection well system 2. If V11>Vmax, the speed of the first submersible electric pump is adjusted to the maximum operating pumping speed Vmax of the first submersible electric pump; if the first submersible electric pump operates at the maximum operating pumping speed Vmax of the first submersible electric pump, the geothermal water extraction diversion system 4 is started, and the second heat recovery system starts to work.

[0122] By designing an inlet temperature sensing module in the heat exchange re-injection well system, it is prevented that the re-injection water flowing into the heat exchange re-injection well system cannot fully exchange heat due to the low temperature of the re-injection water, and when the inlet temperature sensing module detects that the temperature is lower than Amin, the central control module controls to open the extraction geothermal water diversion system, so that the geothermal water flows directly into the heat exchange re-injection well system for heat exchange, thereby improving the heat exchange efficiency, eliminating the situation where the system units work ineffectively, and achieving the most economical operation effect; setting the pump speed evaluation value, when it meets the standard pump speed evaluation range, the pump speed is adjusted according to achieve efficient heat exchange of the system, when it is not in the standard pump speed evaluation range, relying solely on adjusting the pump speed cannot avoid the low efficiency of the system heat exchange, and will also cause waste of the unit's working efficiency.

[0123] Specifically, when A<Amin, the second heat recovery system is started. The central control module is provided with an operation evaluation value Kb of the second submersible electric pump 41 and an adjustment parameter F of the pump speed of the first submersible electric pump 108 to the operation evaluation value. The setting is K=(Amin-A)×E4+(V12-Vmax)×F, where E4 is the geothermal water temperature adjustment parameter for the start-up operation of the second submersible electric pump 41, and V12=V11 or V'.

[0124] When K>Kb, the initial operating speed of the second submersible electric pump 41 does not meet the heat exchange demand of the heat exchange reinjection well system 2, and the central control module adjusts the pumping speed of the second submersible electric pump;

[0125] When K≤Kb, the initial operating speed of the second submersible electric pump 41 meets the heat exchange demand of the heat exchange reinjection well system 2 , and the central control module does not adjust the speed of the second submersible electric pump 41 .

[0126] Specifically, the second submersible electric pump 41 operates at an initial pumping speed V3, driving geothermal water into the diversion pipe 42. When K>Kb, the central control module adjusts the second submersible electric pump 41. The speed of the adjusted second submersible electric pump 41 is V3', and V3'=V3+K×E5 is set, where E5 is the pumping speed adjustment parameter of the second submersible electric pump 41 based on the operation evaluation value of the second submersible electric pump.

[0127] The speed of the second submersible electric pump in the geothermal water diversion system is determined through the inlet temperature sensing module and the first submersible electric pump. When the operating value of the second submersible electric pump is greater than the operating evaluation value Kb, the central control module accelerates the second submersible electric pump. When it is less than the operating evaluation value Kb, the central control module does not adjust the pump speed of the second submersible electric pump, and the second submersible electric pump operates at the initial pump speed V3. By adjusting different pump speeds, the heat exchange in the system is made more sufficient.

[0128] Specifically, the outlet temperature sensing module 214 detects the temperature of the geothermal water about to flow out of the heat exchange recharge well system 2, and obtains the geothermal water temperature B about to flow out of the heat exchange recharge well system 2. The central control module is provided with a third heat recharge system start evaluation temperature Bmax.

[0129] When B≤Bmax, the temperature of the geothermal water flowing out of the heat exchange recharge well system 2 meets the system recharge temperature, and the central control module does not adjust the heat regeneration system or open the geothermal water reflow system 5 due to the water temperature flowing out of the heat exchange recharge well system;

[0130] When B>Bmax, if the pumping speed of the first submersible electric pump 108 is greater than the minimum operating pumping speed Vmin of the first submersible electric pump, the pumping speed of the submersible electric pump 18 is adjusted, and the adjusted pumping speed of the first submersible electric pump is set to V21, V21=V2-(B-Bmax)×E6, wherein V2 is one of V, V', and V", and E6 is the deceleration adjustment parameter of the first submersible electric pump for the geothermal water temperature that is about to flow out of the heat exchange reinjection well system 2; if the first submersible electric pump operates at the minimum operating pumping speed Vmin of the first submersible electric pump, the reinjection geothermal water return system 5 is started, and the third heat recovery system starts to work until B≤Bmax.

[0131] By setting an outlet temperature sensing module in the heat exchange recharge well system, resource waste caused by insufficient heat exchange due to the recharge water temperature flowing out of the heat exchange recharge well system being too high is prevented. When the temperature detected by the outlet temperature sensing module is higher than Bmax, the central control module starts the recharge geothermal water reflow system, allowing the geothermal water to flow into the system again for heat exchange, thereby improving the heat exchange efficiency and achieving the most economical operation effect.

[0132] Specifically, when B>Bmax, the third regenerative heat system is activated. The central control module is provided with an operating evaluation value Kc of the third submersible electric pump 51 and an adjustment parameter F1 of the pump speed of the first submersible electric pump 108 for the operating evaluation value. The setting is K=(B-Bmax)×E7+(Vmin-V22)×F1, where E7 is the operating adjustment parameter for the third submersible electric pump 51 based on the temperature of the reinjected geothermal water, and V22=V21 or V'.

[0133] When K>Kc, the initial operating speed of the third submersible electric pump 51 does not meet the recharging demand of the heat exchange recharging system 2, and the central control module adjusts the pumping speed of the third submersible electric pump 51;

[0134] When K<Kc, the initial operating speed of the third submersible electric pump 51 meets the recharge demand of the heat exchange recharge system 2 , and the central control module does not adjust the speed of the third submersible electric pump 51 .

[0135] Specifically, the third submersible electric pump 51 operates at an initial pump speed V4, driving geothermal water into the diversion pipe 52. When K>Kc, the central control module adjusts the third submersible electric pump 51. The speed of the adjusted third submersible electric pump 51 is V4', and V4'=V4+K×E8 is set, where E8 is the pump speed adjustment parameter of the third submersible electric pump 51 based on the operation evaluation value of the third submersible electric pump.

[0136] The calculation compensation parameters and the calculation adjustment parameters described in the present invention have two functions: one is to balance the left and right dimensions of the formula, and the other is to adjust the numerical results. In this embodiment, no specific assignment is performed. In addition, the calculation formulas in this embodiment are used to intuitively reflect the adjustment relationship between the various numerical values, such as positive correlation and negative correlation. Unless otherwise specified, the parameter values ​​that are not specifically limited to numerical values ​​are all positive.

[0137] By designing an outlet temperature sensing module in the heat exchange recharge well system, it is prevented that the heat exchange is not completed due to the recharge water temperature flowing out of the heat exchange recharge well system being too high, thereby preventing energy waste. Therefore, when the outlet temperature sensing module detects that the temperature is higher than Bmax, the central control module starts the recharge geothermal water reflow system, allowing the recharged geothermal water to flow back into the heat exchange pumping well system for secondary heat exchange, and does not flow back into the underground until the temperature value detected by the outlet temperature sensing module in the heat exchange recharge well system is lower than Bmax.

[0138] Specifically, the open casing 101, 201 used to connect the heat exchange pumping well system 1 and the heat exchange recharge well system 2 is fully cemented with G-grade cement between the well wall.

[0139] By selecting G-grade cementing cement with high strength, strong fluidity, low viscosity and good pumpability, which is more stable after solidification, the entire section between the open casing and the well wall used to connect the heat exchange pumping well system and the heat exchange reinjection well system is cemented, which prevents geothermal water and reinjection water from entering the upper formation and polluting the upper cold water layer; at the same time, it also prevents the upper cold water layer from flowing out to cool the geothermal water.

[0140] Specifically, the heat exchange pumping well system 1 and the heat exchange recharging well system 2 are open casing

[0141] 101, 201 and the upper low-temperature section of the two-open casing 102, 202 are evenly coated with an environmentally friendly thermal insulation coating.

[0142] By selecting lightweight, low-thermal-conductivity, and environmentally friendly thermal insulation coatings, the unnecessary temperature loss caused by geothermal water transferring high-temperature heat to low-temperature strata during the upwelling process due to the low temperature of the upper strata is reduced. Environmentally friendly thermal insulation coatings are applied to the inner walls of some casings to allow geothermal water to more fully exchange heat with the heat exchange tubes, resulting in better heat exchange effects. In addition, the use of volatile-free, VOC-free, non-toxic, and green environmentally friendly coatings is more low-carbon and environmentally friendly, protecting the environment.

[0143] Specifically, the heat exchange reinjection well system 2 is sealed and vacuumed.

[0144] By sealing and vacuuming, air is prevented from entering the water body, which would cause blockages such as bubbles when it is reinjected into the thermal reservoir.

[0145] Specifically, the single-open casing 101, 201, the double-open casing 102, 202, the water filter pipe 109, 209 and the heat exchange pipe 103, 203 are petroleum seamless steel pipes.

[0146] By selecting lighter petroleum seamless steel pipes with the same strength, it can withstand greater pressure, and has high pressure resistance, good toughness, long pipe sections and fewer interfaces.

[0147] Specifically, the inner tubes 104 and 204 are made of polymer composite insulation material, and the softened water is injected from the annulus between the inner tubes 104 and 204 and the heat exchange tubes 103 and 203 and flows out from the center of the inner tubes 104 and 204.

[0148] By adopting this technical solution, the heat exchange contact area is expanded, allowing heat exchange with both the rock formation and geothermal water, reducing energy loss. Furthermore, softened water circulates within the heat exchange tubes and inner pipes, preventing corrosion and scaling, making the pipes more durable.

[0149] Specifically, the first submersible electric pump 108 has a small displacement and only disturbs the geothermal water to form a thermal convection effect, but does not extract the geothermal water.

[0150] The submersible pump is lowered into the annulus between the heat exchange tubes and the heat exchange well casing. Due to the limited space in the annulus between the heat exchange tubes and the heat exchange well casing, only a small-displacement submersible pump can be used. The submersible pump's primary function is to disturb the geothermal water, creating heat convection between the wells, and it does not extract geothermal water. This effectively prevents future violations such as over-extraction and excessive extraction. It meets the requirement of 100% raw water reinjection and supports sustainable development principles.

[0151] Working principle, heat exchange method of three-tube convection conduction high-efficiency heat exchange geothermal well group system, the heat exchange steps include:

[0152] (1) Cold softened water is injected through the annular gap between the heat exchange tube and the inner tube; (2) The geothermal water is driven to circulate by the submersible electric pump, and the geothermal water releases heat through the heat exchange tube during the upward flow; (3) Cold softened water exchanges heat from the formation and geothermal water through the heat exchange tube during the downward flow; (4) The hot softened water after heat exchange flows out of the inner tube under the action of the ground circulation pump, and the heat is used to turn back into cold softened water, and then enters the heat exchange pumping well to continue circulating heat exchange, repeating step (1); (5) The geothermal tail water after heat exchange passes through the ground water treatment system and then is exchanged. The heat recharge well system recharges the formation, and the geothermal tail water transfers the remaining heat to the heat exchange pipe during its downward movement; (6) The cold softened water continues to exchange heat from the formation and the geothermal tail water through the heat exchange pipe during its downward flow; (7) The hot softened water after heat exchange flows out of the inner pipe under the action of the ground circulation pump, and after the heat is utilized, it turns back into cold softened water and enters the heat recharge well to continue circulating heat exchange, repeating step (1); (8) The geothermal tail water after the residual heat exchange enters the heat reservoir, absorbs the heat in the heat reservoir through flow to form a closed cycle, and repeats step (2).

[0153] The entire three-tube convection conduction high-efficiency heat exchange geothermal well group system is divided into two closed water circulation systems. One is the geothermal water closed circulation system, which uses a submersible electric pump to bring a small amount of geothermal water out of the wellbore of the heat exchange pumping well system. The geothermal water continuously transfers heat to the heat exchange pipes during the rising process. At the same time, the flow of geothermal water can carry heat from far away in the formation faster. The temperature of the geothermal tail water after heat exchange is still high, and the heat can continue to be transferred to the heat exchange pipes of the heat exchange reinjection well system, and finally reinjected into the formation to form a closed convection circulation system. The other is the softened water heat exchange circulation system, which sends softened water into the heat exchange pipes through the annulus between the heat exchange pipes and the inner pipes. The heat exchange pipes exchange heat with the flowing geothermal water and the formation, thereby improving the heat exchange efficiency.

[0154] In addition, a central control system and a temperature sensing module are set up to control the operation of different heat recovery systems by detecting the geothermal water temperature at different periods, thereby preventing energy loss and waste of system unit work caused by insufficient heat exchange due to overheating of geothermal water and too low temperature. By controlling the pump speed of the submersible electric pump, when the geothermal water temperature is high, the pump speed is slowed down to allow sufficient heat exchange of the geothermal water. When the geothermal water temperature is low, the pump speed is accelerated to prevent unnecessary heat loss and energy waste.

[0155] The present application utilizes both heat conduction and heat convection to efficiently absorb underground heat for application. Geothermal water is brought out from the wellbore of the heat exchange pumping well system, and heat is continuously transferred to the heat exchange pipe during the rising process. In addition, softened water is sent into the heat exchange pipe through the annulus between the heat exchange pipe and the inner pipe. The heat exchange pipe exchanges heat with the flowing geothermal water and the formation, thereby improving the heat exchange efficiency.

[0156] The geothermal water after heat exchange is finally reinjected into the stratum to form a closed convection circulation system. Since the extraction of geothermal water is only for the purpose of establishing a heat convection mechanism, the extraction volume is very small, so 100% raw water reinjection can be achieved, which will not cause the groundwater level to drop. It has the advantages of environmental protection, low carbon, and heat extraction without water extraction.

[0157] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0158] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A three-tube convection conduction high-efficiency heat exchange geothermal well group system, characterized by: include, The first heat recovery system, including the heat exchange pumping well system, the heat exchange reinjection well system and the surface water treatment system, serves as the main operating system of the high-efficiency heat exchange geothermal well group system. It can extract geothermal water from the ground, transfer the heat of the geothermal water to cold softened water, and reinject the geothermal water after the energy transfer is completed into the ground; a second heat recovery system, comprising the first heat recovery system and a geothermal water extraction diversion system, for supplementing heat exchange when the first heat recovery system is insufficiently heated, the geothermal water extraction diversion system being arranged between the geothermal water extraction outlet and the surface water treatment system; A third heat recovery system, comprising the first heat recovery system and a geothermal water recirculation system, is configured to perform heat exchange again when the geothermal water recirculated in the first heat recovery system is too hot. The geothermal water recirculation system is disposed between the outlet of the heat exchange recirculation well system and the outlet of the extracted geothermal water. detecting the temperature of geothermal water that has not undergone heat exchange to determine whether to activate the first heat regeneration system, and determining the pumping speed of the first submersible electric pump in the first heat regeneration system when activated; determining whether to adjust the pumping speed of the first submersible electric pump and activate the second heat regeneration system by detecting the temperature of geothermal water that has passed through the surface water treatment system; and determining whether to adjust the pumping speed of the first submersible electric pump and activate the third heat regeneration system by detecting the temperature of geothermal water that is about to flow out of the heat exchange recharge well system; a central control module, connected to the first heat regeneration system, the second heat regeneration system, and the third heat regeneration system, respectively, for adjusting the working state of each component; The heat exchange pumping well system of the first heat recovery system includes: An initial temperature sensing module, which is connected to the central control module and is disposed at the bottom of the first heat recovery system, serves as a temperature detection device for the heat exchange pumping well system and is used to detect the temperature of the extracted geothermal water; a first submersible electric pump, connected to the central control module, for pumping geothermal water to the first heat recovery system; a first heat exchange tube set, which is a tube assembly that transfers heat from geothermal water to cold softened water; The heat exchange tube set includes: An open casing, as the well wall pipe of the heat exchange pumping well, provides a passage for the geothermal water to flow from the production layer to the ground. road; The double-open casing is used as the wall pipe of the heat exchange pumping well to provide a passage for the geothermal water to flow from the production layer to the ground. The diameter of the first open casing is larger than that of the second open casing; Heat exchange pipes are placed in the heat exchange pumping well and are used to connect the cold softened water inflow pipeline; An inner tube, placed inside the heat exchange tube, for connecting to a hot softened water outflow pipeline; A thermal insulation coating is used to reduce heat dissipation of the system, and the thermal insulation coating is evenly applied to the upper low-temperature sections of the first-open casing and the second-open casing; cementing section, used to stabilize the system; A pipe plug, an externally threaded pipe fitting used to plug the internal thread at the end of the pipe, and is arranged at the bottom of the heat exchange pipe; The water filter pipe, as the well wall pipe of the heat exchange pumping well, can take in geothermal water and filter the soil or rock particles around the well wall to support and protect the well wall; A heat storage layer is placed around the double-open casing and the water filter pipe, and is used to keep the hot water in the pipeline warm; A specially made water stop is placed on the upper part of the heat reservoir; The first submersible electric pump is placed in the annular space between the open casing and the heat exchange tube.

2. A three-tube convection conduction high-efficiency heat exchange geothermal well group system according to claim 1, wherein The characteristics are, The geothermal water extraction diversion system of the second heat recovery system includes: a second submersible electric pump, connected to the central control module, for pumping geothermal water to the second heat recovery system; A diversion pipeline is used to provide a channel for the extracted geothermal water to flow to the surface water treatment system; The heat exchange reinjection well system includes: A second heat exchange tube set, the components of which are the same as those of the first heat exchange tube set; An inlet temperature sensing module, which is connected to the central control module and is disposed at the inlet of the heat exchange recharge well system, serves as a temperature detection device of the heat exchange recharge well system, and is used to detect the temperature of the geothermal water flowing into the heat exchange recharge well system; An outlet temperature sensing module, which is connected to the central control module and is disposed at the outlet of the heat exchange recharge well system, serves as a temperature detection device of the heat exchange recharge well system, and is used to detect the temperature of geothermal water flowing out of the heat exchange recharge well system; The second submersible electric pump is placed between the geothermal water outlet and the surface water treatment system; The geothermal water recirculation system of the third heat recovery system includes: A third submersible electric pump is connected to the central control module and is placed between the outlet of the heat exchange recharge well system and the outlet of the extracted geothermal water, and is used to return the geothermal water to the third heat recovery system; The return pipe is used to provide a channel for the reinjected geothermal water to flow back to the outlet of the extracted geothermal water.

3. The three-tube convection conduction high-efficiency heat exchange geothermal well group system according to claim 1 is characterized in that: The entire three-tube convection conduction type high-efficiency heat exchange geothermal well group system is divided into two closed water circulation systems, one is a geothermal water closed circulation system, and the other is a softened water heat exchange circulation system.

4. The three-tube convection conduction high-efficiency heat exchange geothermal well group system according to claim 2 is characterized in that: The initial temperature sensing module detects the geothermal water temperature to determine whether the current geothermal water meets the minimum temperature requirement for system operation, and determines whether to adjust the operating speed of the first submersible electric pump in the running system based on the detection result.

5. The three-tube convection conduction high-efficiency heat exchange geothermal well system according to claim 4, characterized in that: The first submersible electric pump is provided with an operating speed interval. When the adjusted theoretical operating speed exceeds the operating speed interval, the interval endpoint value is used as the actual operating speed of the first submersible electric pump.

6. A three-tube convection conduction high-efficiency heat exchange geothermal well group system according to claim 5, characterized in that: The inlet temperature sensing module detects the temperature of the geothermal water about to flow into the heat exchange recharge well system to determine whether the recharged geothermal water temperature flowing into the heat exchange recharge well system meets the system heat exchange temperature. If it does not meet the system heat exchange temperature, the pump speed of the first submersible electric pump is adjusted. If the pump speed of the first submersible electric pump reaches the maximum interval endpoint value, the geothermal water extraction diversion system is started to enable the second heat recharge system to start working.

7. The high-efficiency heat exchange geothermal well group system according to claim 6, characterized in that: When the second heat regeneration system is started, the central control module is provided with an operation evaluation value of the second submersible electric pump to determine whether the initial operation speed of the second submersible electric pump meets the heat exchange requirement of the heat exchange recharge well system. When the actual operation value is greater than the operation evaluation value, the central control module adjusts the pumping speed of the second submersible pump.

8. The three-tube convection conduction high-efficiency heat exchange geothermal well system according to claim 5, characterized in that: The outlet temperature sensing module detects the temperature of the geothermal water about to flow out of the heat exchange recharge well system to determine whether the recharged geothermal water temperature flowing out of the heat exchange recharge well system meets the system recharge temperature. If it does not meet the system recharge temperature, the pump speed of the first submersible electric pump is adjusted. If the pump speed of the first submersible electric pump reaches the minimum interval endpoint value, the recharged geothermal water return system is started, and the third heat recovery system starts to work.

9. The three-tube convection conduction high-efficiency heat exchange geothermal well system according to claim 8, characterized in that: When the third heat regeneration system is started, the central control module is provided with an operation evaluation value of the third submersible electric pump to determine whether the initial operation speed of the third submersible electric pump meets the reinjection requirement of the heat exchange reinjection well system. When the actual operation value is greater than the operation evaluation value, the central control module adjusts the pumping speed of the third submersible pump.

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