阅读说明：本技术 一种增强型超长重力热管地热开发系统 (Enhanced type super-long gravity heat pipe geothermal development system ) 是由 蒋方明 李志斌 黄文博 陈娟雯 岑继文 于 2021-09-23 设计创作，主要内容包括：本发明公开了一种增强型超长重力热管地热开发系统,涉及地热能开发领域,本系统通过将高热导率物质和相变材料形成的高热导率相变复合材料填入具有足够裂隙或者孔隙的地下岩体中,提高地下岩体的热导率,形成地下强化换热系统,地下强化换热系统能够快速的将离热管远处热量传递至热管蒸发段进行换热,增大了热管的采热范围,提高了采热率,同时利用相变材料在高温条件下相变为液体,能够完全与地下岩体及热管外壁进行接触,不存在接触热阻。其次,在热管绝热段采用热管内保温管、绝热段真空管、以及热管外保温物质进行保温处理,减少了热量的损失,提高了系统的热产出。(The invention discloses an enhanced type ultralong gravity heat pipe geothermal exploitation system, which relates to the field of geothermal energy exploitation and is characterized in that a high-thermal conductivity phase-change composite material formed by a high-thermal conductivity substance and a phase-change material is filled into an underground rock mass with enough cracks or pores, so that the thermal conductivity of the underground rock mass is improved, an underground heat-transfer-enhanced system is formed, the underground heat-transfer-enhanced system can quickly transfer heat far from a heat-off pipe to an evaporation section of the heat pipe for heat transfer, the heat-collecting range of the heat pipe is enlarged, the heat-collecting rate is improved, meanwhile, the phase-change material is changed into liquid under the high-temperature condition, the liquid can be completely contacted with the underground rock mass and the outer wall of the heat pipe, and no contact thermal resistance exists. And secondly, the heat insulation section of the heat pipe adopts an inner heat insulation pipe of the heat pipe, a vacuum pipe of the heat insulation section and an outer heat insulation material of the heat pipe for heat insulation treatment, so that the heat loss is reduced, and the heat output of the system is improved.)

1. An enhanced ultralong gravity heat pipe geothermal development system, for a geothermal well having a near-well fracture, comprising:

the underground heat exchange strengthening unit is used for filling a phase change composite material made of a phase change material and a high-heat-conductivity substance into the crack;

the gravity heat pipe unit is used for exchanging heat with the underground heat strengthening and exchanging unit of the geothermal well and putting heat obtained by heat exchange into application through a plurality of built-in circulating pipelines; and the number of the first and second groups,

a heat preservation unit for ensuring heat loss inside the system.

2. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein the fractures comprise a primary fracture and a secondary fracture.

3. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, the gravity heat pipe unit comprises a gravity heat pipe, a ground application, a liquid storage tank and a circulating working medium, the gravity heat pipe, the ground application and the liquid storage tank form a closed circulating loop, the gravity heat pipe is arranged in a geothermal well with an enhanced heat exchange unit, a good heat path is formed by the phase change composite material filled in the crack, the heat far away from the gravity heat pipe is quickly transferred to the heat pipe for heat exchange, the circulating working medium absorbs heat at the evaporation section of the gravity heat pipe and is vaporized, the gaseous circulating working medium passes through the heat insulation section of the gravity heat pipe and enters the ground through a steam regulating valve for application, and the circulating working medium is liquefied after releasing heat and enters the liquid storage tank, and the liquid circulating working medium enters the gravity heat pipe through the flow dividing valve and the liquid regulating valve.

4. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein the insulation unit comprises an external heat pipe insulation, a heat pipe body insulation, an internal heat pipe insulation, wherein,

the heat pipe external heat preservation comprises the step of backfilling a substance with the heat conductivity lower than a set value in the peripheral area outside the gravity heat pipe, or wrapping a substance with the heat conductivity lower than the set value on the pipe wall of the gravity heat pipe;

the heat pipe body is insulated by adopting a pipe body with the heat conductivity lower than a set value;

the heat preservation in the heat pipe is realized by arranging a heat preservation pipe made of a material with the heat conductivity lower than a set value in the gravity heat pipe.

5. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein the phase change composite material comprises an organic phase change material, an inorganic phase change material, and a eutectic phase change material; the high-thermal-conductivity substance comprises graphene, carbon nanotubes and copper.

6. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein the high thermal conductivity substance is in a shape comprising a granular, powdered form.

7. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein the geothermal well is at least one well.

8. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein at least one gravity heat pipe is associated with the geothermal well.

9. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein the gravity heat pipes are of equal or varying diameter.

10. The enhanced ultralong gravity heat pipe geothermal development system of claim 1, wherein the system is used for dry hot rock type geothermal resource exploitation or geothermal resource exploitation of any formation.

Technical Field

The invention relates to the field of geothermal energy development, in particular to an enhanced type ultralong gravity heat pipe geothermal development system.

Background

Geothermal energy has received wide attention from countries in the world due to its advantages of being pollution-free, not affected by weather and climate, etc. Among them, deep geothermal energy is considered as the future of geothermal energy due to its huge reserves. Currently, deep geothermal exploitation systems mainly comprise an enhanced geothermal system and a single-well underground heat exchange system, and the enhanced geothermal system has been proposed for nearly 50 years, but due to the existing main problems: the problems of high drilling cost, unstable fracturing effect, loss of circulating working media, scaling in a well and the like cause that the drilling well does not run commercially all the time; the single-well coaxial underground heat exchange system is still in the development stage, and several single-well underground heat exchange systems which are tested at present comprise: the results of super C projects of Weijis, Weisbard and Germany in Sweden show that the heat collecting effect of the heat exchange system is poor, and the underground heat exchange system needs to consume extra pump work in the operation process.

The heat pipe can rapidly transmit heat from the high-temperature section to the low-temperature section by utilizing the phase change of working media in the pipe. The heat pipe has the characteristics of high heat transfer rate, excellent isothermal property and the like, and is one of the most effective heat transfer devices at present. Patents ZL201710343194.9 and ZL201910328413.5 disclose super-long gravity assisted heat pipes that can carry out deep geothermal exploitation, have broken through bottlenecks such as hydrops, gas-liquid roll-up, but because the underground rock mass of low heat conduction outside of tubes, the great degree of low heat conductivity of the rock mass outside of tubes has restricted this heat pipe and has adopted hot system performance.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides an enhanced type ultralong gravity heat pipe geothermal development system which can improve the heat conductivity of rocks in an evaporation section area of a heat pipe, improve the heat transfer rate and enlarge the heat collection range of the heat pipe, thereby improving the heat collection rate of the heat pipe, and meanwhile, the heat loss is reduced by adopting heat preservation measures in a heat insulation section of the heat pipe, so that the heat output of the whole system is improved.

In order to achieve the above object, the technical solution of the present invention is as follows:

an enhanced ultralong gravity heat pipe geothermal development system for a geothermal well having a near-well fracture, comprising:

the underground heat exchange strengthening unit is used for filling a phase change composite material made of a phase change material and a high-heat-conductivity substance into the crack;

the gravity heat pipe unit is used for exchanging heat with the underground heat strengthening and exchanging unit of the geothermal well and putting heat obtained by heat exchange into application through a plurality of built-in circulating pipelines; and the number of the first and second groups,

a heat preservation unit for ensuring heat loss inside the system.

The enhanced ultralong gravity heat pipe geothermal exploitation system as described above, further wherein the fractures comprise main fractures and secondary fractures.

The enhanced ultralong gravity heat pipe geothermal exploitation system further comprises a gravity heat pipe, a ground application, a liquid storage tank and a circulating working medium, the gravity heat pipe, the ground application and the liquid storage tank form a closed circulation loop, at least part of the gravity heat pipe extends into the ground and is connected with the geothermal well, a good heat path is formed by the phase-change composite material filled in the crack, the heat far away from the gravity heat pipe is quickly transferred to the heat pipe for heat exchange, the circulating working medium absorbs heat at the evaporation section of the gravity heat pipe and is vaporized, the gaseous circulating working medium passes through the heat insulation section of the gravity heat pipe and enters the ground through a steam regulating valve for application, and the circulating working medium is liquefied after releasing heat and enters the liquid storage tank, and the liquid circulating working medium enters the gravity heat pipe through the flow dividing valve and the liquid regulating valve.

The enhanced ultralong gravity heat pipe geothermal exploitation system further comprises a heat pipe external heat preservation unit, a heat pipe body heat preservation unit and a heat pipe internal heat preservation unit, wherein,

the heat pipe external heat preservation comprises the step of backfilling a substance with the heat conductivity lower than a set value in the peripheral area outside the gravity heat pipe, or wrapping a substance with the heat conductivity lower than the set value on the pipe wall of the gravity heat pipe;

the heat pipe body is insulated by adopting a pipe body with the heat conductivity lower than a set value;

the heat preservation in the heat pipe is realized by arranging a heat preservation pipe made of a material with the heat conductivity lower than a set value in the gravity heat pipe.

The enhanced ultralong gravity heat pipe geothermal exploitation system comprises a phase change composite material, a phase change material and a eutectic phase change material.

The enhanced ultralong gravity heat pipe geothermal exploitation system as described above, further wherein the high thermal conductivity substance includes graphene, carbon nanotubes, and copper.

The enhanced ultralong gravity heat pipe geothermal exploitation system as described above, further wherein the shape of the high thermal conductivity substance includes granular shape and powder shape.

The enhanced ultralong gravity heat pipe geothermal development system is characterized in that the geothermal well is at least one well.

The enhanced ultralong gravity heat pipe geothermal development system is characterized in that at least one gravity heat pipe is arranged corresponding to the geothermal well.

The enhanced ultralong gravity heat pipe geothermal development system is characterized in that the gravity heat pipes are of equal diameter or variable diameter.

The system is further used for exploitation of geothermal resources of a dry heat rock type or geothermal resources of any stratum.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the invention, a dendritic or blood vessel-shaped path is formed by means of the near-well fracture with the main fracture and the secondary fracture, and the high-thermal-conductivity phase-change composite material prepared from the phase-change material and the high-thermal-conductivity substance is filled into the near-well fracture, so that the thermal conductivity of the rock can be effectively improved, the heat collection range of the ultralong gravity heat pipe is increased, the heat transfer rate in the rock is improved, and the integral heat collection rate of the system is improved.

(2) By means of the characteristic that the phase-change material is changed into liquid at high temperature, the heat pipe can be completely contacted with the rock mass and the outer wall of the heat pipe, and thermal contact resistance does not exist.

(3) By using the heat insulation measure of the heat insulation section, the heat loss can be reduced to the maximum extent, thereby increasing the heat output of the system.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of an enhanced ultra-long gravity heat pipe geothermal exploitation system used in an embodiment;

FIG. 2 shows the shape of a lateral near-well fracture in the example.

Description of reference numerals: 1. a near-well fracture; 2. a phase change composite material; 3. a geothermal well; 4. circulating the working medium; 5. a liquid storage tank; 6. ground application; 7. a flow divider valve; 8. a liquid regulating valve; 9. a gas regulating valve; 10. an ultra-long gravity heat pipe; 11. a vacuum tube; 12. a heat pipe inner heat preservation pipe; 13. and preserving heat outside the heat pipe.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Example (b):

it should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. Furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, as they may be fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1 to 2, fig. 1 is a schematic diagram of an enhanced ultra-long gravity heat pipe geothermal development system adopted in an embodiment; FIG. 2 shows the shape of a lateral near-well fracture in the example. The invention provides an enhanced type super-long gravity heat pipe geothermal exploitation system, which can improve the thermal conductivity of rocks in an evaporation section area of a heat pipe, improve the heat transfer rate and enlarge the heat collection range of the heat pipe, thereby improving the heat collection rate of the heat pipe, and meanwhile, the heat loss is reduced by adopting heat preservation measures in a heat insulation section of the heat pipe, so that the heat output of the whole system is improved.

The system comprises a geothermal well 3 underground reinforced heat exchange unit, a gravity heat pipe unit and a heat preservation unit, wherein the geothermal well 3 underground reinforced heat exchange unit is used for filling a phase change composite material 2 made of a phase change material and a high-heat-conductivity substance into the crack; the gravity heat pipe unit is used for exchanging heat with the underground heat-strengthening heat exchange unit of the geothermal well and putting heat obtained by heat exchange into application through a plurality of built-in circulating pipelines; and the heat preservation unit is used for ensuring the heat loss in the system. In certain embodiments, the fractures include a main fracture and secondary fractures.

As an alternative embodiment, in some embodiments, the gravity assisted heat pipe unit comprises a gravity assisted heat pipe, a ground application 6, a liquid reservoir 5 and a cycle fluid 4, the gravity assisted heat pipe, the ground application 6 and the reservoir 5 form a closed circulation loop, the gravity heat pipe at least partially extends into the ground and is connected with the geothermal well 3, a good heat path is formed by the phase-change composite material 2 filled in the crack, the heat far away from the gravity heat pipe is quickly transferred to the heat pipe for heat exchange, the circulating working medium 4 absorbs heat at the evaporation section of the gravity heat pipe to be vaporized, the gaseous circulating working medium 4 enters the ground application 6 through the heat insulation section of the gravity heat pipe and the steam regulating valve, the circulating working medium 4 is liquefied after releasing heat and enters the liquid storage tank 5, and the liquid circulating working medium 4 enters the gravity heat pipe through the flow dividing valve 7 and the liquid regulating valve 8.

As an alternative implementation manner, in some embodiments, the heat preservation unit includes heat pipe external heat preservation, heat pipe body heat preservation, and heat pipe internal heat preservation, where the heat pipe external heat preservation includes backfilling a material with a thermal conductivity lower than a set value in an outer circumferential region of the gravity heat pipe, or wrapping a material with a thermal conductivity lower than a set value, such as heat preservation cotton, on a pipe wall of the gravity heat pipe; the heat preservation of the heat pipe body adopts a pipe body with the heat conductivity lower than a set value, such as a vacuum pipe 11 and the like; the heat preservation in the heat pipe adopts the heat preservation pipe that the thermal conductivity is lower than the material of setting value and makes to place in the gravity heat pipe, like PPH pipe etc..

As an alternative implementation, in some embodiments, the phase change composite material 2 includes an organic phase change material, an inorganic phase change material, and a eutectic phase change material. The high-thermal-conductivity substance comprises graphene, carbon nanotubes and copper. The shape of the high-thermal conductivity substance comprises granular and powdery shapes.

As an alternative, in some embodiments, the geothermal well 3 is at least one well.

As an alternative, in some embodiments, there is at least one gravity heat pipe corresponding to the geothermal well 3.

As an alternative, in some embodiments, the gravity assisted heat pipes have equal or variable diameters.

As an alternative embodiment, in some embodiments, the system is used for geothermal resource production in the dry heat rock type, or in any formation.

As shown in figure 1, the enhanced type ultra-long gravity heat pipe geothermal exploitation system is used for exploiting geothermal resources. The heat exchanger comprises a geothermal well underground reinforced heat exchange unit, an ultra-long gravity heat pipe unit, a heat preservation unit and a ground application 6; the underground heat exchange strengthening unit of the geothermal well comprises a near-well crack 1, a high-thermal-conductivity phase-change composite material 2 and the geothermal well 3, the ultra-long gravity heat pipe unit comprises a circulating working medium 4, a liquid storage tank 5, a ground application 6, a flow dividing valve 7, a liquid regulating valve 8, a gas regulating valve 9 and a heat pipe 10, and the heat insulation unit comprises a heat pipe heat insulation section vacuum pipe body 11, a heat pipe inner heat insulation pipe 12 and a heat pipe outer heat insulation substance 13. Sequentially placing an evaporation section of a heat pipe 10, a heat insulation section of the heat pipe 10 with a vacuum pipe 11 and an internal heat insulation pipe 12 into a geothermal well 3 which is provided with enough near-well cracks 1 and is filled with a phase change material 2 with high heat conductivity, forming a good heat path by virtue of the phase change material 2 with high heat conductivity filled in the near-well cracks 1, and quickly transferring heat to the heat pipe from a position far away from the heat pipe for heat exchange; after the heat pipe 10 is placed, adding heat insulation materials to the outer area of the heat insulation section of the heat pipe; the heat pipe 10 is connected with the steam regulating valve 9, the ground application 6, the liquid storage tank 5, the flow dividing valve 7 and the liquid regulating valve 8 in sequence, and is connected with the heat pipe 10 again to form a closed loop.

When the device operates, the in-pipe circulation working medium 4 is vaporized and ascended after obtaining heat at the evaporation section of the heat pipe 10, enters the ground application 6 through the steam regulating valve 9 after passing through the heat insulation section of the heat pipe 10, enters the liquid storage tank 5 after being liquefied after releasing heat, enters the inside of the heat pipe 10 through the flow dividing valve 7 and the liquid regulating valve 8, and gradually obtains heat and is vaporized again when flowing back to the evaporation section of the heat pipe.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention accordingly. All equivalent changes or modifications made in accordance with the spirit of the present disclosure are intended to be covered by the scope of the present disclosure.