Sustainable cross-season geothermal energy development system

Abstract

The present invention proposes a sustainable cross-season geothermal energy development system, including: a geothermal well, an underground outer pipe, a switchable geothermal well seal, an insulating casing, an underground inner pipe, a multi-stage plate exchanger, a heat pump, a user, a circulating water tank, a renewable heat source, a cascade utilization system circulating pump, a cross-season non-heat system circulating pump, a summer cooling system circulating pump and a plurality of valves, wherein the switchable geothermal well seal is arranged between the low temperature zone and the high temperature zone of the geothermal reservoir, and the switchable geothermal well seal is switched to enable the sustainable cross-season geothermal energy development system to enter different energy development modes. The present invention has a wide range of applications, good long-term operation economy, and significant environmental benefits. It completely solves the problems of small energy supply of a single geothermal well and heat attenuation in long-term use, and improves the heat source stability and economic optimality of geothermal energy utilization, while protecting the sustainability of geothermal resources while developing geothermal energy.

Description

Technical Field

[0001] The invention relates to the field of energy technology, and in particular to a sustainable cross-season geothermal energy development system. Background Art

[0002] Sustainable cross-seasonal geothermal energy development technology is mainly used in the geothermal energy development and utilization industry, including geothermal heating, cooling and other fields, as well as related fields combining geothermal energy with planting and breeding industries.

[0003] At present, geothermal energy extraction and heating mainly use two forms: wells and single wells. Single well utilization mainly uses heat extraction without water extraction. This is limited by local geothermal conditions. The single well extraction capacity is directly related to the single well energy supply capacity. At present, the measures to expand the energy supply capacity of a single well mainly include conventional geothermal energy cascade utilization, peak-shaving multi-energy complementation using gas boilers, electric boilers and other equipment, etc. Among them, the cascade utilization of geothermal energy and the peak-shaving multi-energy complementation of gas boilers, electric boilers and other equipment require increased system investment and equipment operating costs, which directly affects economic efficiency.

[0004] At present, the relevant technology has proposed a system that uses the mid-deep non-interference geothermal heat exchange hole as a cold and heat source. The system includes a cooling outer tube arranged in the geothermal heat exchange hole, a middle tube is arranged in the cooling outer tube, a central tube is arranged in the middle tube, the bottom end of the cooling outer tube is located at the lower surface of the cold source area, the bottom end of the cooling outer tube is connected to the outer connecting tube, the bottom end of the middle tube is connected to the top of the cold and heat converter, the bottom end of the cold and heat converter is connected to the heating heat exchange tube through the inner connecting tube, the central tube runs through to the bottom of the heating heat exchange tube, and is connected at the bottom of the heating heat exchange tube, the bottom end of the heating heat exchange tube is connected to the stabilizing cone, and the cold and heat converter The side is provided with an outflow hole connected to the refrigeration outer pipe, a sealing ring is provided between the outer connecting pipe and the inner connecting pipe, and the cold-heat converter is located on the upper part of the sealing ring, and the top of the refrigeration outer pipe is provided with three-port water distributors with valves, one of which connects the return water port with the middle pipe, one of which connects the refrigeration outlet with the refrigeration outer pipe, and the other connects the heating outlet with the central pipe, so as to form a cold source utilization loop of the return water port-middle pipe-cold-heat converter-refrigeration outer pipe-refrigeration outlet in summer, and a heat source utilization loop of the return water port-middle pipe-cold-heat converter-inner connecting pipe-heating heat exchange pipe-central pipe-heating outlet in winter. However, the system has the following disadvantages: the energy supply capacity of the system depends greatly on the local geothermal resources, and the scope of application cannot be expanded; the ground temperature gradually decreases during the energy supply process in winter, but in summer, only the soil layer within 0 to 1000 meters is heated, and long-term use will lead to a year-on-year decrease in the energy supply capacity of a single well.

[0005] At present, relevant technologies have also proposed a solar energy and geothermal energy assisted centralized heating system, which includes a heat source, an absorption heat pump, a heat user, a solar collector, a buried pipe, a number of circulating water pumps and various connecting pipes and accessories. The high-temperature hot water from the primary heating network of the heat source drives the absorption heat pump, and the soil source is used as the low-level heat source of the absorption heat pump. The absorption heat pump evaporator is connected to the buried pipe, and the heat medium absorbs heat from the soil and releases heat in the absorption heat pump evaporator; during the heating period, the solar collector is used as an auxiliary heat source of the heating system and is combined with the buried pipe for heating. During the non-heating period, the solar collector is used as a reinjection heat source to restore the soil temperature around the buried pipe and maintain the balance of soil thermal energy; the return water of the secondary heating network is heated by the absorption heat pump and then sent to the heat user through the secondary heating network. However, the system has the following disadvantages: the system is mainly heated by the heat network, and geothermal energy and solar energy are only used as auxiliary heat sources, not as power sources; the geothermal energy used by the system only involves shallow buried heat pipes and cannot be extended to medium and deep geothermal utilization systems, and geothermal resources are not fully utilized. Summary of the invention

[0006] The present invention aims to solve at least one of the above technical problems.

[0007] To this end, the purpose of the present invention is to propose a sustainable cross-seasonal geothermal energy development system, which has a wide range of applications, good long-term economic efficiency, and significant environmental benefits. It completely solves the problems of small energy supply from a single geothermal well and heat attenuation after long-term use, and improves the heat source stability and economic optimality of geothermal energy utilization, thereby protecting the sustainability of geothermal resources while developing geothermal energy.

[0008] In order to achieve the above-mentioned purpose, an embodiment of the present invention proposes a sustainable cross-seasonal geothermal energy development system, including: a geothermal well, an underground outer pipe, a switchable geothermal well seal, an insulating casing, an underground inner pipe, a multi-stage plate exchanger, a heat pump, a user, a circulating water tank, a renewable heat source, a cascade utilization system circulating pump, a cross-seasonal non-heat system circulating pump, a summer cooling system circulating pump and a plurality of valves, wherein the multi-stage plate exchanger, the heat pump, the user, the circulating water tank, the renewable heat source, the cascade utilization system circulating pump, the cross-seasonal non-heat system circulating pump, and the summer cooling system circulating pump are selectively connected through the plurality of valves, wherein the switchable geothermal well seal is arranged between the low temperature zone and the high temperature zone of the geothermal reservoir, and by switching the switchable geothermal well seal, the sustainable cross-seasonal geothermal energy development system enters different energy development modes.

[0009] In addition, the sustainable cross-season geothermal energy development system according to the above embodiment of the present invention may also have the following additional technical features:

[0010] In some examples, the different energy development modes include at least: a winter multi-energy complementary heating mode, a summer cooling mode, and a cross-seasonal heat storage mode.

[0011] In some examples, in winter, the switchable geothermal well seal is opened, and a passage from the wellhead to the bottom of the well is formed between the downhole outer pipe and the insulating casing, and circulating water can circulate in the entire well; in summer, the switchable geothermal well seal is closed, and the geothermal well is separated into two layers, and circulating water can only circulate in the area between the switchable geothermal well seal and the wellhead.

[0012] In some examples, in the winter multi-energy complementary heating mode, the circulating water is injected into the heat exchange space formed between the downhole outer pipe and the insulating casing using the potential energy of the circulating water tank, and the heat of the geothermal reservoir is extracted after sufficient heat exchange. The hot water after heat exchange is sent to the multi-stage plate exchanger along the downhole inner pipe, and heat is supplied to users through the multi-stage plate exchanger and heat pump heat exchange.

[0013] In some examples, the multi-stage plate exchanger includes at least a first-stage plate exchanger and a second-stage plate exchanger. The tail water after heat exchange on the primary side of the first-stage plate exchanger is heated by the renewable heat source, and after the water supply temperature is increased, it enters the second-stage plate exchanger and the heat pump in a cascade utilization cycle. The tail water after sufficient heat exchange in the second-stage plate exchanger is circulated to the circulating water tank and re-enters the geothermal well for circulating heat exchange.

[0014] In some examples, in the summer cooling mode, the low temperature zone of the geothermal reservoir is used as the cold source of the user's cooling cycle, the user's heat is injected from the downhole inner pipe, flows through the switchable geothermal well seal, and heat is exchanged between the insulating casing and the downhole outer pipe. The cold water after the heat exchange then provides cooling to the user.

[0015] In some examples, in the inter-seasonal heat storage mode, the renewable heat source is injected from the downhole inner pipe, flows through the switchable geothermal well insulation, and heat is exchanged between the insulating casing and the downhole outer pipe to exchange heat to the low-temperature zone of the geothermal reservoir.

[0016] In some examples, the start time and period of the inter-seasonal heat storage mode may be determined according to the type of the renewable heat source.

[0017] In some examples, the regional depth of the coverage area of ​​the inter-seasonal heat storage is determined according to the maximum heating temperature of the renewable heat source.

[0018] In some examples, the renewable heat source includes at least one of solar energy, wind energy, and biomass energy.

[0019] The sustainable cross-season geothermal energy development system according to the embodiment of the present invention has the following beneficial effects:

[0020] (1) The heating and cooling functions are realized by a single well, which maximizes the development of the single well capacity, reduces the initial investment and operating costs, and has excellent economic efficiency.

[0021] (2) Adopt underground heat exchange technology to obtain heat instead of water, comprehensively utilize renewable heat sources, and give full play to the significant environmental benefits of renewable energy including geothermal energy.

[0022] (3) Renewable heat sources are introduced for cross-seasonal heat storage, and low-temperature and high-temperature zones are divided according to the quality of renewable energy, which improves the recovery capacity of geothermal gradients, protects the long-term sustainable utilization of geothermal energy resources, and ensures the safety and stability of energy supply.

[0023] (4) Supplement renewable heat sources into the cascade utilization system and improve the overall energy utilization efficiency through multi-energy complementarity, thereby improving the economic benefits of project development and operation.

[0024] (5) The diversity of renewable heat source types and the freedom of entry points have greatly expanded the scope of applicability of geothermal energy development, making geothermal energy development no longer restricted by a single geothermal resource, which is conducive to the promotion and application of geothermal energy.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 It is a schematic structural diagram of a sustainable cross-seasonal geothermal energy development system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0029] In the description of the present invention, it is necessary to understand that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] The following describes a cross-season geothermal energy development system for sustainable utilization according to an embodiment of the present invention in conjunction with the accompanying drawings.

[0032] Figure 1 FIG. 1 is a schematic diagram of a structure of a sustainable cross-season geothermal energy development system according to an embodiment of the present invention. Figure 1 As shown, the sustainable cross-season geothermal energy development system includes: a geothermal well 1, an underground outer pipe 2, a switchable geothermal well seal 3, an insulating casing 4, an underground inner pipe 5, a multi-stage plate exchanger, a heat pump 8, a user 9, a circulating water tank 10, a renewable heat source 11, a cascade utilization system circulating pump 12, a cross-season non-heat system circulating pump 13, a summer cooling system circulating pump 14 and a plurality of valves. The multi-stage plate exchanger, the heat pump 8, the user 9, the circulating water tank 10, the renewable heat source 11, the cascade utilization system circulating pump 12, the cross-season non-heat system circulating pump 13, and the summer cooling system circulating pump 14 are selectively connected through a plurality of valves, wherein the switchable geothermal well seal 3 is set between the low temperature zone and the high temperature zone of the geothermal reservoir, and by switching the switchable geothermal well seal 3, the sustainable cross-season geothermal energy development system enters different energy development modes.

[0033] exist Figure 1 In the example shown, the multi-stage plate exchanger and heat pump 8, the cascade utilization system circulation pump 12, the cross-seasonal heat-free system circulation pump 13, the summer cooling system circulation pump 14, etc. constitute the energy cascade utilization system, and the underground outer pipe 2 and the underground inner pipe and the insulation casing 4 constitute the underground heat exchange system. The multiple valves include at least valves 15 to 22.

[0034] In one embodiment of the present invention, different energy development modes include at least: a winter multi-energy complementary heating mode, a summer cooling mode and a cross-seasonal heat storage mode.

[0035] As mentioned above, the switching of different energy development modes is mainly achieved by setting a switchable geothermal well seal 3 between the low temperature zone and the high temperature zone of the geothermal reservoir. In winter, the switchable geothermal well seal 3 is opened, and a passage from the wellhead to the bottom of the well is formed between the downhole outer pipe 2 and the insulating casing 4, and the circulating water can circulate in the whole well; in summer, the switchable geothermal well seal 3 is closed, and the geothermal well 1 is separated into two layers, and the circulating water can only circulate in the area between the switchable geothermal well seal 3 and the wellhead.

[0036] In one embodiment of the present invention, in the winter multi-energy complementary heating mode, the heat of the geothermal reservoir is extracted by underground heat exchange technology, combined with the renewable heat source 11, and heated to the user 9 through the cascade utilization system, for example, according to Figure 1 The solid arrow in the middle is circulated. Specifically, the circulating water is injected into the heat exchange space formed between the underground outer pipe 2 and the insulation casing 4 by using the potential energy of the circulating water tank 10. After sufficient heat exchange, the heat of the geothermal reservoir is extracted. The hot water after heat exchange is sent to the multi-stage plate exchanger along the underground inner pipe 5, and heat is supplied to the user 9 through the multi-stage plate exchanger and the heat pump 8.

[0037] Among them, Figure 1 As shown, the multi-stage plate exchanger includes at least but not limited to the first stage plate exchanger 6 and the second stage plate exchanger 7. The tail water after the heat exchange on the primary side of the first stage plate exchanger 6 is heated by the renewable heat source 11, and then enters the cascade utilization cycle of the second stage plate exchanger 7 and the heat pump 8 after the water supply temperature is increased. In this way, the geothermal energy and the energy of the renewable heat source 11 can be superimposed to increase the heating amount. The tail water after sufficient heat exchange in the second stage plate exchanger 7 is circulated to the circulating water tank 10 and re-enters the geothermal well for circulating heat exchange. It should be noted that Figure 1 In the example shown, the multi-stage board switches only include the first-stage board switch 6 and the second-stage board switch 7. However, the number of board switches can be increased according to resource conditions.

[0038] In one embodiment of the present invention, in the summer cooling mode, the low temperature zone of the geothermal reservoir is used as the cold source of the user cooling cycle, the heat of the user 9 is injected through the underground inner pipe 5, flows through the switchable geothermal well seal 3, and heat is exchanged between the insulating casing 4 and the underground outer pipe 2. The cold water after heat exchange then provides cooling to the user 9.

[0039] In one embodiment of the present invention, in addition to winter heating, renewable heat sources can be used to carry out inter-seasonal heat storage. In the inter-seasonal heat storage mode, the renewable heat source 11 is injected from the underground inner pipe 5, flows through the switchable geothermal well isolation seal 3, and exchanges heat between the insulating casing 4 and the underground outer pipe 2, and exchanges heat to the low-temperature area of ​​the geothermal reservoir, thereby compensating for the ground temperature drop caused by winter heating, restoring the temperature of the geothermal reservoir, and achieving the effect of sustainable utilization of geothermal energy.

[0040] The start time and cycle of the cross-season heat storage mode can be determined according to the type of renewable heat source 11. For example, solar heat storage can be started during the period with good lighting effect.

[0041] In one embodiment of the present invention, the renewable heat source 11 includes at least one of solar energy, wind energy, and biomass energy.

[0042] In one embodiment of the present invention, the regional depth of the coverage area of ​​the inter-seasonal heat storage is determined according to the maximum heating temperature of the renewable heat source. Specifically, the low temperature area of ​​the geothermal reservoir is also used as the main area of ​​inter-seasonal heat storage here, and the depth of the area will be determined according to the maximum heating temperature of the renewable heat source 11, and the underground depth with matching temperature is selected.

[0043] In summary, the sustainable cross-seasonal geothermal energy development system of the embodiment of the present invention mainly includes geothermal wells, renewable heat sources, energy cascade utilization systems (plate exchangers + heat pump systems), switchable geothermal well seals, downhole heat exchange systems (geothermal well downhole outer pipes + geothermal well downhole inner pipes + insulation casings), etc., which combine renewable heat sources with geothermal energy, and improve the effects of traditional geothermal energy supply technology through cross-season heat storage, multi-energy complementarity, and energy cascade utilization, thereby expanding the economic benefits of single-well development; the overall design of the system adopts a switchable and selectable design, and the entry point of the renewable heat source can be arbitrarily determined according to user needs, thereby improving the flexibility of use; the type of renewable heat source can be freely selected according to the local resources of the project, thereby increasing the scope of use for future development; the system level of geothermal energy cascade utilization can be adjusted according to actual needs. That is, this sustainable cross-seasonal geothermal energy development system has a wide range of applications, good long-term economic efficiency, and significant environmental benefits. It completely solves the problems of small energy supply from a single geothermal well and heat attenuation after long-term use, and improves the heat source stability and economic optimality of geothermal energy utilization. While developing geothermal energy, it protects the sustainability of geothermal resources and is suitable for large-scale development, promotion and application.

[0044] The sustainable cross-season geothermal energy development system according to the embodiment of the present invention has the following beneficial effects:

[0045] (1) The heating and cooling functions are realized by a single well, which maximizes the development of the single well capacity, reduces the initial investment and operating costs, and has excellent economic efficiency.

[0046] (2) Use underground heat exchange technology to extract heat instead of water, make comprehensive use of renewable heat sources, and give full play to the significant environmental benefits of renewable energy including geothermal energy.

[0047] (3) Renewable heat sources are introduced for cross-seasonal heat storage, and low-temperature and high-temperature zones are divided according to the quality of renewable energy, which improves the recovery capacity of geothermal gradients, protects the long-term sustainable utilization of geothermal energy resources, and ensures the safety and stability of energy supply.

[0048] (4) Add renewable heat sources to the cascade utilization system and improve the overall energy utilization efficiency through multi-energy complementarity, thereby improving the economic benefits of project development and operation.

[0049] (5) The diversity of renewable heat source types and the freedom of entry points have greatly expanded the scope of applicability of geothermal energy development, making geothermal energy development no longer restricted by a single geothermal resource, which is conducive to the promotion and application of geothermal energy.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0051] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A sustainable and cross-seasonal geothermal energy development system, characterized in that: include: Geothermal well, underground outer pipe, switchable geothermal well isolation seal, insulation casing, underground inner pipe, multi-stage plate exchanger, heat pump, user, circulating water tank, renewable heat source, cascade utilization system circulating pump, cross-season non-heat system circulating pump, summer cooling system circulating pump and multiple valves, the multi-stage plate exchanger, heat pump, user, circulating water tank, renewable heat source, cascade utilization system circulating pump, cross-season non-heat system circulating pump, summer cooling system circulating pump are selectively connected through the multiple valves, wherein, The switchable geothermal well seal is arranged between the low temperature zone and the high temperature zone of the geothermal reservoir, and by switching the switchable geothermal well seal, the sustainable cross-seasonal geothermal energy development system enters different energy development modes; The different energy development modes include at least: winter multi-energy complementary heating mode, summer cooling mode and cross-season heat storage mode; In winter, the switchable geothermal well seal is opened, and a passage from the wellhead to the well bottom is formed between the downhole outer pipe and the insulation casing, so that circulating water can circulate in the whole well; in summer, the switchable geothermal well seal is closed, and the geothermal well is divided into two layers, and the circulating water can only circulate in the area between the switchable geothermal well seal and the wellhead; In the inter-seasonal heat storage mode, the renewable heat source is injected from the downhole inner pipe, flows through the switchable geothermal well insulation, and heat is exchanged between the insulating casing and the downhole outer pipe to exchange heat to the low-temperature zone of the geothermal reservoir.

2. The sustainable cross-season geothermal energy development system according to claim 1 is characterized in that: In the winter multi-energy complementary heating mode, the circulating water is injected into the heat exchange space formed between the underground outer pipe and the insulating casing by utilizing the potential energy of the circulating water tank. After sufficient heat exchange, the heat of the geothermal reservoir is extracted. The hot water after heat exchange is sent to the multi-stage plate exchanger along the underground inner pipe, and heat is supplied to users through the multi-stage plate exchanger and heat pump heat exchange.

3. The sustainable cross-seasonal geothermal energy development system according to claim 2 is characterized in that: The multi-stage plate exchanger includes at least a first-stage plate exchanger and a second-stage plate exchanger. The tail water after heat exchange on the primary side of the first-stage plate exchanger is heated by the renewable heat source, and then enters the second-stage plate exchanger and the heat pump cascade utilization cycle after the water supply temperature is increased. The tail water after sufficient heat exchange in the second-stage plate exchanger is circulated to the circulating water tank and re-enters the geothermal well for circulating heat exchange.

4. The sustainable cross-seasonal geothermal energy development system according to claim 1 is characterized in that: In the summer cooling mode, the low temperature area of ​​the geothermal reservoir is used as the cold source of the user's cooling cycle, the user's heat is injected from the underground inner pipe, flows through the switchable geothermal well seal, and heat is exchanged between the insulating casing and the underground outer pipe. The cold water after heat exchange is used to cool the user.

5. The sustainable cross-seasonal geothermal energy development system according to claim 1 is characterized in that: The start time and cycle of the inter-seasonal heat storage mode may be determined according to the type of the renewable heat source.

6. The sustainable cross-seasonal geothermal energy development system according to claim 5 is characterized in that: The regional depth of the coverage area of ​​the inter-seasonal heat storage is determined according to the maximum heating temperature of the renewable heat source.

7. The sustainable cross-seasonal geothermal energy development system according to claim 5 or 6, characterized in that: The renewable heat source includes at least one of solar energy, wind energy and biomass energy.

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