Double-well or multi-well power generation system using ultra-long gravity heat pipe

Abstract

The invention discloses a double-well or multi-well power generation system using ultra-long gravity heat pipes, and relates to the technical field of medium-deep layer geothermal power generation, the system comprises at least two gravity heat pipes, a gas collection tank, an expansion machine, a power generator, a condenser and a liquid storage tank, the gravity heat pipes are inserted into the ground, the gas collection tank is arranged above the gravity heat pipes, and the expansion machine is arranged above the gas collection tank. The top ends of the at least two gravity assisted heat pipes are connected to a gas inlet of the gas collecting tank through pipelines, a gas outlet of the gas collecting tank is connected to a gas inlet of the expansion machine through a pipeline, the expansion machine drives the power generator to generate power, an exhaust gas outlet of the expansion machine is connected to the liquid storage tank through the condenser, and the liquid storage tank is connected to a gas outlet of the gas collecting tank through a pipeline. And the liquid storage tank is respectively communicated with the at least two gravity assisted heat pipes through pipelines. The medium-deep geothermal development cost is greatly reduced, and meanwhile the power generation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of mid-deep geothermal power generation, especially the technical field of hot dry rock geothermal power generation, and in particular to a dual or multi-well power generation system utilizing an ultra-long gravity heat pipe. Background Art

[0002] Geothermal energy is a renewable new energy source with great potential and is widely favored. In the context of future energy transformation, geothermal energy is considered to be one of the key energy sources for sustainable development. Geothermal energy has many advantages in energy utilization, which gives it broad application prospects: (1) Renewable and sustainable: Geothermal energy is a renewable energy source, and the heat energy reserves inside the earth are almost infinite. Compared with limited resources such as fossil fuels, geothermal energy has the characteristics of sustainability and stability, and has less impact on the environment. (2) Environmentally friendly: Geothermal energy utilization does not produce greenhouse gases and pollutants, has no pollution to the environment, has a positive impact on climate change, and is a clean energy source. (3) Stable and reliable: Geothermal energy is stable and is not affected by external factors such as weather and climate. Compared with fluctuating energy sources such as solar energy and wind energy, geothermal energy is more stable and reliable. (4) Wide application: Geothermal energy can not only be used for power generation, heating and hot water, but also in agricultural greenhouses, aquaculture and industrial production. The wide application of geothermal energy gives it broad market prospects and economic potential.

[0003] Deep geothermal energy, especially hot dry rock energy, has huge reserves and is expected to become the basic energy source for the future new energy supply system. The traditional enhanced geothermal system (EGS) model for developing hot dry rock energy connects two or more wells through fracturing and water injection circulation, bringing geothermal energy to the ground through water flow. The problem is that the cost of fracturing technology is high, and it is difficult to achieve efficient connection of wells; when realizing fluid circulation, not only a large amount of pumping power is consumed, but there is also the phenomenon of fluid leakage; during the working fluid circulation process, the working fluid is in direct contact with high-temperature rocks, and the calcium ions, chloride ions and silicate ions contained in the fluid working fluid will cause scaling and corrosion of the pipeline after the fluid flows into the pipeline; excessive use of groundwater resources may cause dangers such as ground subsidence.

[0004] As a highly efficient heat transfer device, heat pipes can transfer heat from one end to the other by using the phase change of the working fluid in the pipe. The above problems can be avoided by using heat pipe technology to exploit geothermal energy. Gravity heat pipes are widely used in industry and agriculture due to their advantages such as simple manufacturing, convenient operation, low cost and high heat transfer efficiency. In recent years, with the development and utilization of new energy in China, gravity heat pipes have gradually been applied to new energy fields such as solar energy and geothermal energy.

[0005] Unlike traditional EGS systems, which require underground connectivity, this greatly reduces the cost of mid- and deep-layer geothermal development while improving power generation efficiency. Summary of the Invention

[0006] Aiming at the deficiencies in the prior art, the present invention provides a dual or multi-well power generation system using ultra-long gravity heat pipes. The heat of the dual or multi-well is extracted to the ground through ultra-long heat pipe technology for efficient power generation, avoiding the problem that the steam outlet and liquid return in a single-well heat pipe steam power generation are completed in the same pipeline, resulting in a decrease in steam temperature and a high liquid content, greatly improving the power generation efficiency, and without the need for downhole connection like a traditional EGS system, greatly reducing the cost of medium and deep geothermal development while improving the power generation efficiency.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A dual or multi-well power generation system using ultra-long gravity heat pipes, which includes: at least two gravity heat pipes, a gas collector, an expander, a generator, a condenser, and a liquid storage tank. Among them, the gravity heat pipes are inserted into the ground, the gas collector is arranged above the gravity heat pipes, the tops of at least two of the gravity heat pipes are respectively connected to the gas inlet of the gas collector through pipelines, the gas outlet of the gas collector is connected to the gas inlet of the expander through a pipeline, the expander drives the generator to generate electricity, the exhaust gas outlet of the expander is connected to the liquid storage tank through the condenser, and the liquid storage tank is respectively connected to at least two of the gravity heat pipes through pipelines.

[0009] The dual or multi-well power generation system using ultra-long gravity heat pipes as described above, further includes a cooling tower, and the cooling tower exchanges heat with the condenser through a heat exchange pipeline.

[0010] The dual or multi-well power generation system using ultra-long gravity heat pipes as described above, further, the gravity heat pipes are vertically inserted into the ground.

[0011] The dual or multi-well power generation system using ultra-long gravity heat pipes as described above, further, the gravity heat pipes are inserted into the ground obliquely or bent.

[0012] The dual or multi-well power generation system using ultra-long gravity heat pipes as described above, further, the number of the gravity heat pipes is two.

[0013] The dual or multi-well power generation system using ultra-long gravity heat pipes as described above, further, one of the gravity heat pipes is connected to the gas inlet of the gas collector through a first pipeline, and the first pipeline is provided with a first valve; the other gravity heat pipe is connected to the gas inlet of the gas collector through a second pipeline, and the second pipeline is provided with a second valve.

[0014] The dual or multi-well power generation system using ultra-long gravity heat pipes as described above, further, the condenser is connected to the liquid storage tank through a third pipeline, and the third pipeline is provided with a third valve.

[0015] The dual or multi-well power generation system using ultra-long gravity heat pipes as described above. Further, the liquid storage tank is respectively connected to one of the gravity heat pipes through a fourth pipeline and a fifth pipeline, and a fifth valve and a sixth valve are respectively provided on the fourth pipeline and the fifth pipeline. The liquid storage tank is respectively connected to the other gravity heat pipe through a sixth pipeline and a seventh pipeline, and a fourth valve and a seventh valve are respectively provided on the sixth pipeline and the seventh pipeline.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention avoids the problems that the steam outlet and the liquid return in the single-well heat pipe steam power generation are completed in the same pipeline, resulting in a decrease in steam temperature and a high liquid content, and greatly improves the power generation efficiency. Moreover, through the liquid return of the liquid storage tank, there is no need to inject with a high-pressure pump, reducing the pump power consumption of the system operation itself. There is no need to connect between the bottom wells of the multi-well system, greatly reducing the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 : It is a schematic structural diagram of the dual-well / multi-well power generation system using ultra-long gravity heat pipes of the present invention;

[0019] In the figure: 1. The first heat pipe body; 2. The second heat pipe body; 3. The gas collecting tank; 4. The expander; 5. The generator; 6. The condenser; 7. The cooling tower; 8. The liquid storage tank; 9. The first valve; 10. The second valve; 11. The third valve; 12. The fourth valve; 13. The fifth valve; 14. The sixth valve; 15. The seventh valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0021] Embodiment:

[0022] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" in the embodiments of the present invention and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0023] In the description of the present invention, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically defined. In addition, unless otherwise clearly specified and defined, 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 directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the face of the need for downhole connection like the traditional EGS system, while greatly reducing the cost of medium and deep geothermal development and improving the power generation efficiency, the present invention provides a dual or multi-well power generation system using ultra-long gravity heat pipes. Through the ultra-long heat pipe technology, the heat of the dual or multi-well is extracted to the ground for efficient power generation, avoiding the problem that the steam outlet and liquid return are completed in the same pipeline in the single-well heat pipe steam power generation, which reduces the steam temperature and has a high liquid content, greatly improving the power generation efficiency, and without the need for downhole connection like the traditional EGS system, while greatly reducing the cost of medium and deep geothermal development and improving the power generation efficiency.

[0025] The working principle of geothermal energy extraction using a gravity heat pipe is as follows: By adding working fluids such as water and liquid ammonia into the gravity heat pipe and evacuating the inside to a negative pressure state with a vacuum pump; at the initial moment, the liquid is at the bottom of the heat pipe. After the evaporation section is heated by the high-temperature rocks or high-temperature groundwater in the deep underground and reaches the evaporation temperature of the liquid, the liquid absorbs heat and vaporizes into steam. Under the pressure difference of a small pressure, the steam flows through the adiabatic section to the ground condensation section. After absorbing heat through the heat exchanger in the ground condensation section, it releases heat and condenses into a liquid. Subsequently, under the action of gravity, it flows back to the evaporation section. This cycle repeats, extracting the heat energy of the deep underground dry hot rocks to the ground for power generation and heating. From the above extraction process, it can be seen that using a gravity heat pipe to extract geothermal energy resources does not require consuming pump work, etc., which can reduce costs. In addition, only heat is taken and no water is taken during the whole process, which can avoid problems such as ground settlement and water resource pollution, and has significant advantages.

[0026] See Figure 1 As shown in this embodiment, a dual or multi-well power generation system using an ultra-long gravity heat pipe includes: at least two gravity heat pipes, a gas collector 3, an expander 4, a generator 5, a condenser 6, and a liquid storage tank 8. Among them, the gravity heat pipes are inserted into the ground, the gas collector is arranged above the gravity heat pipes, the tops of at least two of the gravity heat pipes are respectively connected to the inlet of the gas collector 3 through pipelines, the outlet of the gas collector 3 is connected to the inlet of the expander 4 through a pipeline, the expander 4 drives the generator 5 to generate electricity, the liquid outlet of the expander 4 is connected to the liquid storage tank 8 through the condenser 6, and the liquid storage tank 8 is respectively connected to at least two of the gravity heat pipes through pipelines.

[0027] The tube body of the ultra-long gravity heat pipe can be vertical, or inclined or slightly bent. The vertical shape is beneficial to the flow of steam inside the tube, with the minimum steam flow resistance. While the inclined or bent shape can facilitate the expansion of the heat absorption area and increase the geothermal extraction output. A reasonable shape can be selected according to the geothermal resources and application objectives.

[0028] In this embodiment, the steam of one of the gravity heat pipes enters the expander, drives the generator to generate electricity and then enters the condenser. The condensed liquid working fluid enters the liquid storage tank. After passing through the liquid storage tank, the valve connected to the condenser is closed, and the two valves connected to the other gravity heat pipe are opened, so that the pressure of the liquid storage tank and the gravity heat pipe is balanced. Then the liquid flows into the gravity heat pipe under the action of gravity. At this time, this gravity heat pipe does not supply gas to the generator set. After the liquid injection is completed, the functions of the two gravity heat pipes are swapped. After the heat of the gravity heat pipe with liquid injection is balanced, it supplies gas, while the gravity heat pipe that supplied gas before becomes the liquid injection mode through a similar switch valve control method. By such cyclic control, each gravity heat pipe can achieve separation of gas supply and liquid injection, and at the same time, the generator set can obtain continuous gas supply for power generation.

[0029] The advantage of the power generation system of this embodiment is that it avoids the problem that the steam outlet and liquid return in a single-well heat pipe steam power generation are completed in the same pipeline, which reduces the steam temperature and increases the liquid content, greatly improving the power generation efficiency. Moreover, through the liquid return of the liquid storage tank, there is no need to inject with a high-pressure pump, reducing the pump power consumption of the system itself. There is no need to connect the bottom wells of the multi-well system, greatly reducing the construction cost.

[0030] Refer again to Figure 1 , the number of the gravity heat pipes is two, namely the first heat pipe body 1 located on the left side of the attached drawing and the second heat pipe body 2 located on the right side of the attached drawing. The first heat pipe body 1 is connected to the air inlet of the gas collecting tank 3 through a first pipeline, and a first valve 9 is provided on the first pipeline; the second heat pipe body 2 is connected to the air inlet of the gas collecting tank 3 through a second pipeline, and a second valve 10 is provided on the second pipeline. The condenser 6 is connected to the liquid storage tank 8 through a third pipeline, and a third valve 11 is provided on the third pipeline. The liquid storage tank 8 is respectively connected to the first heat pipe body 1 through a fourth pipeline and a fifth pipeline, and a fifth valve 13 and a sixth valve 14 are respectively provided on the fourth pipeline and the fifth pipeline. The liquid storage tank 8 is respectively connected to the second heat pipe body 2 through a sixth pipeline and a seventh pipeline, and a fourth valve 12 and a seventh valve 15 are respectively provided on the sixth pipeline and the seventh pipeline. The heat pipe body can be in a vertical shape, or in an inclined or curved shape to meet the requirements of different occasions.

[0031] By controlling the on-off state of the valves, the purpose of supplying gas to the expander 4 and the generator 5 by two or more first heat pipe bodies 1 and second heat pipe bodies 2 in turn is achieved. The specific operation conditions are as follows:

[0032] Open the first valve 9 and the third valve 11, and close other valves. At this time, the liquid working medium in the first heat pipe body 1 absorbs geothermal energy and turns into steam in the pipe, which then floats up and enters the gas collecting tank 3. After being converted into kinetic energy by the expander 4 to drive the generator 5 to generate electricity, the exhausted gas enters the condenser 6 and condenses into liquid. The heat released by the condenser 6 is absorbed by the cooling tower 7 and dissipated to the environment or directly used for heat utilization such as heating. The liquid working medium then flows into the liquid storage tank 8 for storage. After the stored liquid reaches a certain amount, close the third valve 11, and open the fourth valve 12 and the seventh valve 15. In this way, the pressure in the liquid storage tank 8 rises to the same as that of the second heat pipe body 2, so the liquid in the liquid storage tank 8 naturally flows into the second heat pipe body 2 due to gravity. At the same time, the steam in the first heat pipe body 1 still continuously enters the expander 4 to generate electricity, and the liquid in the condenser 6 is temporarily stored at the bottom of the container. After the liquid storage tank 8 is emptied, close the first valve 9, the fourth valve 12, and the seventh valve 15, and open the second valve 10 and the third valve 11. In this way, the gas collecting tank 3 will inhale the steam from the second heat pipe body 2, stop supplying gas to the first heat pipe body 1, and at the same time, the liquid working medium in the condenser 6 flows into the liquid storage tank 8. After storing a certain amount of liquid working medium, close the third valve 11, and open the fifth valve 13 and the sixth valve 14. In this way, the pressure in the liquid storage tank 8 is the same as that of the first heat pipe body 1, and the liquid in the liquid storage tank 8 naturally flows into the first heat pipe body 1 due to gravity, replenishing the liquid working medium for the first heat pipe body 1. After the first heat pipe body 1 returns to a certain pressure, close the second valve 10, the fifth valve 13, and the sixth valve 14, and open the first valve 9 and the third valve 11, so that the system returns to the initial gas supply state of the first heat pipe body 1, completing a round of complete switching process. In this way, cycle after cycle, the first heat pipe body 1 and the second heat pipe body 2 can alternately supply gas to the expander 4 and alternately replenish the liquid working medium. The gas supply process and the liquid replenishment process of each heat pipe are completely separated, avoiding gas-liquid entrainment and reducing the problems of steam outlet temperature and pressure.

[0033] And so on, the switching of gas supply and liquid return between multiple wells can be realized, so that a larger geothermal area can be utilized for geothermal exploitation, a larger steam generator set can be adopted to improve the power generation efficiency and reduce the cost.

[0034] It should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They 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 operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0035] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is less than that of the second feature.

[0036] In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the essence of the content of the present invention should be covered within the protection scope of the present invention.

Claims

1. A dual or multi-well power generation system using ultra-long gravity heat pipes, characterized in that, it includes: at least two gravity heat pipes, a gas collector, an expander, a generator, a condenser and a liquid storage tank. Among them, the gravity heat pipes are inserted into the ground, the gas collector is arranged above the gravity heat pipes, the tops of at least two of the gravity heat pipes are respectively connected to the air inlet of the gas collector through pipelines, the air outlet of the gas collector is connected to the air inlet of the expander through a pipeline, the expander drives the generator to generate electricity, the exhaust gas outlet of the expander is connected to the liquid storage tank through the condenser, and the liquid storage tank is respectively communicated with at least two of the gravity heat pipes through pipelines.

2. The dual or multi-well power generation system using ultra-long gravity heat pipes according to claim 1, characterized in that, it further includes a cooling tower, and the cooling tower exchanges heat with the condenser through a heat exchange pipeline.

3. The dual or multi-well power generation system using ultra-long gravity heat pipes according to claim 1, characterized in that, the gravity heat pipes are vertically inserted into the ground.

4. The dual or multi-well power generation system using ultra-long gravity heat pipes according to claim 1, characterized in that, the gravity heat pipes are inserted into the ground obliquely or bent.

5. The dual or multi-well power generation system using ultra-long gravity heat pipes according to claim 1, characterized in that, the number of the gravity heat pipes is two.

6. The dual or multi-well power generation system using ultra-long gravity heat pipes according to claim 5, characterized in that, one of the gravity heat pipes is connected to the air inlet of the gas collector through a first pipeline, and a first valve is provided on the first pipeline; the other gravity heat pipe is connected to the air inlet of the gas collector through a second pipeline, and a second valve is provided on the second pipeline.

7. The dual or multi-well power generation system using ultra-long gravity heat pipes according to claim 5, characterized in that, the condenser is connected to the liquid storage tank through a third pipeline, and a third valve is provided on the third pipeline.

8. The dual or multi-well power generation system using ultra-long gravity heat pipes according to claim 5, characterized in that, the liquid storage tank is respectively connected to one of the gravity heat pipes through a fourth pipeline and a fifth pipeline, and a fifth valve and a sixth valve are respectively provided on the fourth pipeline and the fifth pipeline. The liquid storage tank is respectively connected to the other gravity heat pipe through a sixth pipeline and a seventh pipeline, and a fourth valve and a seventh valve are respectively provided on the sixth pipeline and the seventh pipeline.

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