Underground geothermal energy utilization generator set

Abstract

The invention belongs to the technical field of geothermal power generation equipment, and particularly relates to an underground geothermal utilization generator set which comprises an underground heat pipe, a turbine generator, a condenser and a medium storage tank which are sequentially connected. The underground heat pipe comprises an inner pipe and an outer pipe, and the space in the inner pipe is divided into a steam channel and a liquid channel through a partition plate. A flow deflector is installed on the inner pipe, a gap exists between the flow deflector and the inner wall of the outer pipe, a liquid hole and a steam hole are formed in the inner pipe, and a baffle is installed in the liquid channel. A contact net is installed on the flow deflector, the lower end of the contact net is connected with a magnetic bead in series, and the magnetic bead is attached to the inner wall of the outer pipe in an adsorption mode; the structure is simple, the geothermal energy transmission loss is reduced, the geothermal energy power generation utilization rate is increased, the heat exchange performance of the underground heat pipe is improved, it is guaranteed that the liquid film is continuous and stable, the liquid film can be relatively segmented, and therefore the situation that evaporation heat exchange is affected due to too large static pressure is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of geothermal power generation equipment, and specifically relates to a geothermal utilization generator set for downhole use. Background Art

[0002] Geothermal energy is natural heat energy extracted from the earth's crust, and a large amount of heat energy is stored in the molten rock inside the earth. Geothermal energy is a green, low-carbon, and recyclable renewable energy source. In the context of the increasingly scarce energy, the rational development of geothermal resources has become increasingly important, such as using geothermal water for house heating, developing greenhouse agriculture, and hot spring tourism, etc.

[0003] Currently, geothermal power generation technologies mainly include dry steam power generation, flash steam power generation, binary cycle power generation, and Kalina cycle power generation, etc.: Among them, the dry steam power generation system has a simple process, mature technology, is safe and reliable, and the cycle efficiency can reach more than 20%. It is the main form of power generation in high-temperature geothermal fields; The flash steam power generation technology has been widely used in the field of geothermal power generation, especially in medium and high-temperature geothermal fields. The cycle efficiency of the secondary flash steam system is about 15% - 20%; For medium and low-temperature geothermal resources, the binary cycle power generation technology is more applicable. It consists of a geothermal water system and a low-boiling-point medium system, and the cycle efficiency can be increased by 20% - 30% compared with the flash steam power generation technology; The Kalina cycle has its unique advantages in the application field of low-temperature geothermal resources. By adjusting the ratio of ammonia and water, it can adapt to the power generation characteristics of low-temperature geothermal water. The cycle efficiency of the Kalina cycle power generation technology is 20% - 50% higher than that of the Rankine cycle.

[0004] In the process of developing and utilizing low-temperature geothermal resources, the binary cycle and Kalina cycle technologies have broad development prospects. When the existing power generation equipment is in use, it cannot make good use of geothermal resources. Usually, the geothermal energy in the well needs to be absorbed and transmitted to the ground before power generation, which easily leads to the loss of geothermal energy during the transmission process, reducing the utilization rate of geothermal energy, resulting in low power generation efficiency and wasting resources. At the same time, for the ultra-long gravity heat pipes used for collecting geothermal energy, when the length-diameter ratio of the evaporation section is large under geothermal temperature conditions, there are phenomena such as uneven flow of condensed liquid, inability to fully wet the evaporation wall surface, and the condensed liquid returning to the bottom liquid pool to form a cold pool without completely absorbing heat and evaporating. Moreover, if the evaporation section is too long, it may also lead to too deep a depth of the working fluid in the heat pipe. Under the action of too large a static pressure, the pressure on the deep working fluid is higher than the saturated vapor pressure at the corresponding formation temperature, resulting in the inability of the working fluid to vaporize, reducing the heat transfer efficiency, thus limiting the length of the gravity heat pipe and affecting the heat transfer effect. Summary of the Invention

[0005] In order to make up for the deficiencies of the prior art, reduce the loss of geothermal energy transmission, improve the utilization rate of geothermal power generation, and improve the heat transfer performance of the underground heat pipe, ensure the continuity and stability of the liquid film, and enable the liquid film to be relatively segmented, thereby avoiding excessive static pressure and affecting evaporation heat transfer, the present invention proposes a geothermal utilization generator set for underground use.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows: The geothermal utilization generator set for underground use described in the present invention includes an underground heat pipe, a steam turbine generator, a condenser, and a medium storage tank that are connected in sequence; The working medium in the underground heat pipe absorbs heat and vaporizes and then enters the steam turbine generator to do work and generate electricity. The working medium discharged from the steam turbine generator enters the condenser and changes from a gaseous state to a liquid state and then is stored in the medium storage tank. The working medium in the medium storage tank flows back to the underground heat pipe under the action of gravity; The underground heat pipe includes an inner pipe and an outer pipe. The space in the inner pipe is separated into a steam channel and a liquid channel by a partition. The steam channel is connected to the inlet of the steam turbine generator through an outlet pipe, and the liquid channel is communicated with the outlet of the medium storage tank through an inlet pipe; A guide vane with a downward-sloping cross-section is installed on the outer wall of the inner pipe. There is a gap between the guide vane and the inner wall of the outer pipe. Liquid holes and steam holes are opened on the inner pipe. A baffle with an upward-sloping cross-section is installed in the liquid channel. The liquid holes, the baffle, the guide vane, and the steam holes are distributed from top to bottom on the inner pipe and correspond to each other one by one; A contact network is installed on the guide vane, and magnetic beads are connected in series at the lower end of the contact network. The magnetic beads are adsorbed and attached to the inner wall of the outer pipe.

[0007] Preferably, it further includes a secondary generator, a circulation pump, a condenser, and a pressure tank that are connected in sequence. The cycle formed by the working medium in the steam turbine generator is a primary cycle, and the cycle formed by the working medium in the secondary generator is a secondary cycle. Supercritical CO2 is used as the circulating working medium in the secondary cycle; The secondary cycle exchanges heat with the primary cycle at the condenser to utilize the remaining heat of the primary cycle.

[0008] Preferably, the outlet pipe is also communicated with the medium storage tank, and a pressure regulating valve is installed on the pipeline between the outlet pipe and the medium storage tank.

[0009] Preferably, a blocking plate is installed in the liquid channel. The blocking plate is in contact with the baffle. The central angle corresponding to the blocking plate is smaller than the central angle corresponding to the baffle. The outlet of the inlet pipe is aligned with the position between the blocking plate and the inner wall of the outer pipe; A micro-hole area is provided on the side of the baffle facing the center line.

[0010] Preferably, the underground heat pipe includes a heat insulation section and an evaporation section. The evaporation section is located in the high-temperature underground formation. The guide vane is located in the evaporation section, and the distance between the guide vanes in the evaporation section gradually decreases from top to bottom. The guide vane is made of a bimetal sheet or a shape memory metal. After the guide vane is heated and deformed, the gap between the guide vane and the inner wall of the outer pipe increases.

[0011] Preferably, an insulating layer is installed on the inner wall of the inner pipe and the surface of the partition. The insulating layer is composed of multiple reflective layers and heat insulating layers.

[0012] Preferably, contact grooves are formed on the inner wall of the outer pipe, and multiple groups of contact grooves are evenly arranged. The size of the contact groove matches the size of the magnetic bead.

[0013] Preferably, the medium storage tank is installed above the ground through a fixing frame. Multiple groups of underground heat pipes are installed underground. The position of the medium storage tank makes the pipeline distance between the medium storage tank and each underground heat pipe the shortest.

[0014] The beneficial effects of the present invention are as follows: 1. For the geothermal utilization generator set for underground use in the present invention, by setting the underground heat pipe, inner pipe, outer pipe, guide vane, baffle plate, and blocking plate, the working medium directly exchanges heat underground to generate steam, and then the steam directly drives the generator to generate electricity, reducing the number of heat exchanges of the working medium and improving the utilization rate of geothermal energy. At the same time, during the process of using geothermal energy to generate electricity, there is no need to extract and recharge groundwater, avoiding affecting the balance of the groundwater system.

[0015] 2. For the geothermal utilization generator set for underground use in the present invention, by setting the guide vane, baffle plate, blocking plate, liquid channel, and steam channel, the gaseous and liquid working media are isolated from each other to avoid mutual interference, thereby improving the heat exchange effect of the underground heat pipe and the utilization rate of geothermal energy. At the same time, the liquid film on the inner wall of the outer pipe is continuous and stable, improving the heat exchange performance of the underground heat pipe and avoiding the intermittent and blank liquid film on the inner wall of the outer pipe, which affects the utilization of geothermal energy.

[0016] 3. For the geothermal utilization generator set for underground use in the present invention, by setting the medium storage tank and pressure valve, the medium storage tank is installed at a high position through a fixing frame, so that the working medium in the medium storage tank has a large gravitational potential energy, which is convenient for the working medium to be re-injected into the underground heat pipe for self-circulation. At the same time, when the self-circulation of the working medium is not smooth, by adjusting the pressure valve, the gaseous working medium enters the medium storage tank, increasing the pressure in the medium storage tank and further increasing the pressure for injecting the working medium into the underground heat pipe, ensuring the smooth progress of the self-circulation of the working medium and eliminating the need for additional energy to pump the working medium for circulation. Description of the Drawings

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 is a schematic diagram of the principle of the generator set of the present invention; Figure 2 is a perspective view of the underground heat pipe in the generator set of the present invention; Figure 3 is a schematic structural diagram of the underground heat pipe in the generator set of the present invention; Figure 4 is a partial cross-sectional view of the underground heat pipe in the generator set of the present invention; Figure 5 is Figure 3 a partial enlarged view at position A in Figure 6 is Figure 4 a partial enlarged view at position B in In the figure: underground heat pipe 1, steam outlet pipe 11, liquid inlet pipe 12, inner pipe 2, outer pipe 21, contact groove 211, partition plate 22, steam channel 23, steam hole 231, liquid channel 24, liquid hole 241, support 25, baffle 3, blocking plate 31, micro-hole area 32, guide vane 4, contact network 41, magnetic bead 42, medium storage tank 5, turbine generator 51, condenser 52, pressure valve 53, secondary generator 54, pressure tank 55, circulation pump 56. Specific Embodiments

[0019] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0020] As Figures 1 to 6 shown, the geothermal utilization generator set for underground use according to the present invention includes an underground heat pipe 1, a turbine generator 51, a condenser 52, and a medium storage tank 5 that are connected in sequence; The working medium in the underground heat pipe 1 absorbs heat and vaporizes and then enters the turbine generator 51 to do work and generate electricity. The working medium discharged from the turbine generator 51 enters the condenser 52 and changes from a gaseous state to a liquid state and then is stored in the medium storage tank 5. The working medium in the medium storage tank 5 flows back to the underground heat pipe 1 under the action of gravity; The underground heat pipe 1 includes an inner pipe 2 and an outer pipe 21. The space in the inner pipe 2 is divided into a steam channel 23 and a liquid channel 24 by a partition plate 22. The steam channel 23 is connected to the inlet of the turbine generator 51 through a steam outlet pipe 12, and the liquid channel 24 is communicated with the outlet of the medium storage tank 5 through a liquid inlet pipe 12; A flow guide vane 4 with an inclined downward cross-section is installed on the outer wall of the inner tube 2. There is a gap between the flow guide vane 4 and the inner wall of the outer tube 21. Liquid holes 241 and steam holes 231 are formed in the inner tube 2. A baffle 3 with an inclined upward cross-section is installed in the liquid channel 24. The liquid holes 241, the baffle 3, the flow guide vane 4, and the steam holes 231 are distributed from top to bottom on the inner tube 2 and correspond to each other one by one; A contact network 41 is installed on the flow guide vane 4. A magnetic bead 42 is connected in series at the lower end of the contact network 41. The magnetic bead 42 is adsorbed and attached to the inner wall of the outer tube 21; The underground heat pipe 1 is installed underground so that heat exchange occurs between the underground heat pipe 1 and the high-temperature underground formation. The low-boiling organic medium in the underground heat pipe 1 absorbs the underground heat and changes from liquid to gas. After that, the vaporized working medium enters the turbine generator 51 to perform work and generate electricity. Then, the working medium enters the condenser 52 for heat exchange to condense the working medium from gas to liquid, and the liquid working medium enters the medium storage tank 5. After that, the liquid working medium in the medium storage tank 5 re-enters the underground heat pipe 1 by gravity, completing the self-circulation of the working medium. There is no need to use additional energy to drive a pump to provide driving force for the fluid in the system. At the same time, through the absorption of heat and vaporization of the working medium in the underground heat pipe 1, and then directly driving the turbine generator 51 to perform work and generate electricity, the high-temperature and high-pressure gaseous working medium directly performs work and generates electricity, avoiding heat loss caused by heat transfer between multiple media, improving the geothermal utilization efficiency. And during the process of using geothermal energy to generate electricity, groundwater is not mined or recharged, and the balance of the groundwater system is not affected; At the same time, after the liquid working medium enters the liquid channel 24, as the working medium descends, the working medium will be intercepted by the baffle 3. After that, the working medium will flow from the liquid hole 241 to the flow guide vane 4, so that the working medium flows along the guidance of the flow guide vane 4 to the inner wall of the outer tube 21 and forms a liquid film on the inner wall of the outer tube 21, thus facilitating the heat exchange and vaporization of the liquid film with the heat in the external formation through the outer tube 21 to generate gaseous working medium. After that, the gaseous working medium will enter the steam channel 23 from the steam hole 231 and be discharged out of the underground heat pipe 1 from the steam outlet pipe 11; At the same time, since the amount of the working medium intercepted by the baffle 3 per unit time is greater than the amount of the working medium allowed to pass through the liquid hole 241 per unit time, a liquid layer is accumulated between the baffle 3 and the inner wall of the liquid channel 24. The liquid layer is used to seal the liquid hole 241 to prevent the steam after the working medium absorbs heat and vaporizes from flowing back into the liquid channel 24. At the same time, after the accumulated liquid layer gradually increases, the liquid layer will overflow from the edge of the baffle 3 and then be intercepted by the lower baffle 3 again; Meanwhile, the deflector 4 guides the liquid working medium to form a stable and continuous liquid film on the inner wall of the outer tube 21. By providing multiple sets of deflectors 4, the liquid film on the inner wall of the outer tube 21 is divided into multiple regions, thereby enhancing the heat transfer of the underground heat pipe 1, improving the geothermal energy utilization efficiency, and avoiding uneven flow of the liquid film on the inner wall of the outer tube 21, insufficient wetting of the inner wall of the outer tube 21, and intermittent distribution of the liquid film, which affects the efficient evaporation and heat transfer of the underground heat pipe 1; Meanwhile, the contact network 41 below the deflector 4 is adsorbed and close to the inner wall of the outer tube 21 through the magnetic beads 42, further guiding and attaching the working medium flowing down on the deflector 4 to the inner wall of the outer tube 21, thereby forming a continuous and stable liquid film. At the same time, when the working medium is guided by the contact network 41 to flow, the gaps on the contact network 41 will be blocked by the working medium and the flow rate of the working medium on the contact network 41 will be delayed, so that the contact network 41 and the working medium cooperate with each other to seal the gap between the deflector 4 and the inner wall of the outer tube 21, avoiding the steam after the working medium absorbs heat and vaporizes from flowing upward through the gap between the deflector 4 and the inner wall of the outer tube 21, which affects the normal flow of the steam in the underground heat pipe 1 and the heat exchange efficiency of the underground heat pipe 1; Meanwhile, the inner tube 2 is divided into a steam channel 23 and a liquid channel 24, enabling the steam and the liquid to pass through the inner tube 2 without interference, avoiding intense heat exchange between the steam and the liquid, weakening the heat transfer ability of the underground heat pipe 1 and restricting the use of the underground heat pipe 1 over long distances. At the same time, the gap between the inner tube 2 and the outer tube 21 is only used to arrange the liquid film, for efficient evaporation and heat transfer, improving the heat exchange efficiency and utilization rate of the underground heat pipe 1 for geothermal energy. Meanwhile, the inner tube 2 is installed and limited in the outer tube 21 through the bracket 25; Meanwhile, since the gap between the inner tube 2 and the outer tube 21 is only used to arrange the liquid film, the gap between the inner tube 2 and the outer tube 21 can be arranged relatively small. In cooperation with the interception of the working medium by the baffle 3 in the liquid channel 24, the thickness and height of the liquid film arranged in the gap between the inner tube 2 and the outer tube 21 are limited, that is, the quantity of the liquid working medium per unit length in the evaporation section is relatively small, avoiding excessive thickness and height of the liquid film, resulting in too large hydrostatic pressure of the liquid film, which affects the process of heat absorption and vaporization, boiling of the liquid working medium, and the evaporation heat exchange efficiency.

[0021] As an embodiment of the present invention, it further includes a secondary generator 54, a circulation pump 56, a condenser 52, and a pressure tank 55 connected in sequence. The cycle composed of the working medium in the turbine generator 51 is a primary cycle, and the cycle composed of the working medium in the secondary generator 54 is a secondary cycle. Supercritical CO2 is used as the circulating working medium in the secondary cycle; The secondary cycle exchanges heat with the primary cycle at the condenser 52 to utilize the remaining waste heat of the primary cycle; After the working medium in the underground heat pipe 1 enters the turbine generator 51 to do work and generate electricity, there will still be some residual heat in the working medium discharged from the turbine generator 51. At this time, directly cooling and condensing the working medium through the condenser 52 will waste the residual heat in the working medium and increase the energy consumed by the condenser 52 during the condensation process. Therefore, a secondary generator 54 is provided. When the condenser 52 cools and condenses the working medium, heat exchange is performed on the supercritical CO2 medium flowing in the secondary cycle, so that the temperature of the cycle working medium rises and vaporizes, and then enters the turbine expander in the secondary generator 54 to do work and generate electricity, improving the utilization rate of geothermal energy and facilitating the cooling and condensation of the working medium in the condenser 52, and reducing additional energy consumption; At the same time, since the overall unit of the secondary cycle is located on the ground and the unit position is close to the condenser 52, the path of the secondary cycle is relatively short and completely enclosed, greatly improving the sealing performance of the pipeline in the secondary cycle and reducing the possibility of leakage of the cycle working medium.

[0022] As an embodiment of the present invention, the steam outlet pipe 11 is also connected to the medium storage tank 5, and a pressure regulating valve 53 is installed on the pipeline between the steam outlet pipe 11 and the medium storage tank 5; Since the length of the underground heat pipe 1 installed underground is relatively long, there is resistance when injecting the liquid working medium into the underground heat pipe 1, and there is a possibility of affecting the circulating flow of the working medium. At the same time, since the volume inside the medium storage tank 5 is fixed, by adjusting the pressure valve 53, part of the steam discharged from the underground heat pipe 1 enters the medium storage tank 5, increasing the pressure in the medium storage tank 5, thereby using the increased pressure to reduce the difficulty of injecting the liquid working medium into the underground heat pipe 1, ensuring that the working medium can complete the cycle smoothly, and avoiding or reducing additional energy input and pumping the working medium for circulation.

[0023] As an embodiment of the present invention, a blocking plate 31 is installed in the liquid channel 24. The blocking plate 31 is in contact with the baffle 3. The central angle corresponding to the blocking plate 31 is smaller than the central angle corresponding to the baffle 3, and the outlet of the liquid inlet pipe 12 is aligned with the position between the blocking plate 31 and the inner wall of the outer pipe 21; A microporous area 32 is provided on the side of the baffle 3 facing the center line; Since both the gaseous and liquid working media pass through the inner tube 2, although there will be no direct contact between them, heat exchange between them is still inevitable. Therefore, in order to improve the heat transfer efficiency of the underground heat pipe 1, it is necessary to keep them away from each other in the inner tube 2 to avoid and reduce heat exchange between them as much as possible. In this case, a baffle 31 is installed in the liquid channel 24, so that the liquid working medium injected into the liquid channel 24 by the liquid inlet pipe 12 will be blocked by the baffle 31, causing the liquid working medium to cling to the baffle 3 on the liquid channel 24 and reducing the possibility of the liquid working medium splashing and spraying onto the partition 22 in the liquid channel 24. Thus, in the inner tube 2, the liquid working medium and the steam are relatively far away from each other, increasing the distance between them and reducing the heat exchange between them; At the same time, due to the blocking and guiding of the liquid working medium by the baffle 31, when the injection amount of the working medium in the liquid channel 24 is reduced, the liquid working medium can be smoothly intercepted and accumulated by the baffle 3, ensuring that the liquid working medium smoothly passes through the liquid holes 241. Thus, the liquid working medium does not need to completely fill the liquid channel 24, further reducing the heat exchange between the liquid working medium and the gaseous working medium in the inner tube 2 and improving the heat transfer efficiency and heat transfer effect of the underground heat pipe 1; At the same time, by providing a microporous area 32 on the baffle 3, after the working medium accumulates between the baffle 3 and the inner wall of the liquid channel 24, the working medium will gradually reach the microporous area 32, and the working medium will pass through the micropores and fall onto the lower baffle 3. At the same time, after the working medium falls onto the lower baffle 3, the working medium will flow and accumulate along the surface of the baffle 3 until the working medium reaches the microporous area 32 on the lower baffle 3 again. At the same time, through the conduction of the working medium by the microporous area 32, it is convenient for the working medium to flow between two adjacent upper and lower baffles 3, preventing the working medium from overflowing from the edge of the upper baffle 3 and making it difficult for the working medium to enter the lower baffle 3 and easily fall directly to the bottom of the underground heat pipe 1, thus affecting the arrangement of the liquid film on the inner wall of the outer tube 21 of the underground heat pipe 1 and the heat transfer performance of the underground heat pipe 1.

[0024] As an embodiment of the present invention, the underground heat pipe 1 includes a heat insulation section and an evaporation section. The evaporation section is located in the high-temperature underground formation, and the guide vane 4 is located in the evaporation section. The distance between the guide vanes 4 in the evaporation section gradually decreases from top to bottom; The guide vane 4 is made of a bimetallic sheet or a shape memory metal. After the guide vane 4 is heated and deformed, the gap between the guide vane 4 and the inner wall of the outer tube 21 increases; Since the temperature underground gradually increases with the increase in depth, and the evaporation section length of the underground heat pipe 1 in the well is relatively long, the temperature at the lower end of the evaporation section is relatively higher, which intensifies the boiling phenomenon of the liquid film on the inner wall of the outer tube 21 near the lower end of the evaporation section, accelerating the heat absorption and vaporization rate of the liquid film. Therefore, a flow guide piece 4 is made of a bimetal or a shape memory alloy, so that the gap between the flow guide piece 4 and the inner wall of the outer tube 21 increases with the increase in the external formation temperature, thereby accelerating the quantity of the working medium flowing downward, increasing the thickness of the liquid film, ensuring the continuous and stable existence of the liquid film on the inner wall of the outer tube 21, improving the heat transfer capacity of the underground heat pipe 1. At the same time, the heat-conducting piece is deformed by heat, and in cooperation with the increasing arrangement quantity of the flow guide piece 4 from top to bottom, it further accelerates the working medium to enter the gap between the outer tube 21 and the inner tube 2, ensuring the stability and continuity of the liquid film on the inner wall of the outer tube 21, and improving the heat exchange performance of the underground heat pipe 1.

[0025] As an embodiment of the present invention, an insulating layer is installed on the inner wall of the inner tube 2 and the surface of the partition plate 22, and the insulating layer is composed of multiple reflective layers and heat-insulating layers; By arranging multiple reflective layers and heat-insulating layers, the heat isolation effect of the insulating layer is improved, and the heat exchange between the liquid working medium and the gaseous working medium in the inner tube 2 is reduced, thereby improving the utilization rate of geothermal energy. At the same time, since the insulating layer is composed of multiple layers, the thermal resistance between the layers will be increased, improving the heat insulation effect. At the same time, the reflective layer can be selected as an aluminum foil layer, and the heat-insulating layer is made of common heat-insulating materials. At the same time, by installing the insulating layer on the inner wall of the inner tube 2, the insulating layer is in contact with the gaseous working medium in the steam channel 23, reducing the impact and friction on the insulating layer, and avoiding the erosion of the insulating layer after contacting the liquid working medium, which affects the service life of the insulating layer.

[0026] As an embodiment of the present invention, contact grooves 211 are formed on the inner wall of the outer tube 21, and multiple groups of the contact grooves 211 are uniformly arranged; The size of the contact groove 211 matches the size of the magnetic bead 42; By forming the contact grooves 211 on the inner wall of the outer tube 21, the contact area between the liquid working medium and the inner wall of the outer tube 21 is increased. At the same time, since the liquid working medium is blocked by the contact grooves 211 when flowing downward along the inner wall of the outer tube 21, the residence time of the liquid working medium on the inner wall of the outer tube 21 is prolonged, improving the evaporation heat exchange efficiency, and thus improving the heat exchange performance of the underground heat pipe 1; Meanwhile, the magnetic bead 42 and the contact groove 211 are matched with each other. After the magnetic bead 42 is adsorbed to the contact groove 211 under the action of magnetic force, the contact area between the magnetic bead 42 and the contact groove 211 is relatively large, that is, the adsorption stability of the magnetic bead 42 in the contact groove 211 is relatively high. When the liquid working medium flows downward along the inner wall of the outer tube 21, the working medium will not wash away the fit between the contact network 41 and the inner wall of the outer tube 21, so as to avoid affecting the guiding of the working medium by the contact network 41.

[0027] As an implementation mode of the present invention, the medium storage tank 5 is installed above the ground through a fixing frame. A plurality of underground heat pipes 1 are installed underground. The position of the medium storage tank 5 makes the pipeline distance between the medium storage tank 5 and each underground heat pipe 1 the shortest; By setting the fixing frame, there is a relatively large height difference between the medium storage tank 5 and the ground. Thus, the liquid working medium in the medium storage tank 5 has a relatively large gravitational potential energy, which is convenient for the liquid working medium to be reinjected into the underground heat pipe 1, further ensuring that the working medium can smoothly perform self-circulation, avoiding the consumption of additional energy. At the same time, the pressure of the gaseous working medium injected into the medium storage tank 5 is reduced, and the influence on the geothermal energy conversion efficiency is reduced.

[0028] The specific working process is as follows: The underground heat pipe 1 is installed underground. The low-boiling organic medium in the underground heat pipe 1 changes from liquid to gas. Then, it enters the turbine generator 51 to perform work and generate electricity. After that, the working medium enters the condenser 52 for heat exchange, and the working medium that has changed into liquid enters the medium storage tank 5. Then, the liquid working medium in the medium storage tank 5 re-enters the underground heat pipe 1 under the action of gravity, completing the self-circulation of the working medium; Meanwhile, after the liquid working medium enters the liquid channel 24, as the working medium descends, the working medium will be intercepted by the baffle 3. Then, the working medium will flow from the liquid hole 241 to the guide vane 4, and flow along the guide of the guide vane 4 to the inner wall of the outer tube 21, and form a liquid film on the inner wall of the outer tube 21, and exchange heat and vaporize to generate gaseous working medium. Then, the gaseous working medium will enter the steam channel 23 from the steam hole 231 and be discharged from the steam outlet pipe 11; Meanwhile, since the number of working media intercepted by the baffle 3 per unit time is greater than the number of working media allowed to pass through the liquid hole 241 per unit time, a liquid layer is accumulated between the baffle 3 and the inner wall of the liquid channel 24, and the liquid layer is used to seal the liquid hole 241. At the same time, after the accumulated liquid layer gradually increases, the liquid layer will overflow from the edge of the baffle 3 and be intercepted by the lower baffle 3 again; Meanwhile, the liquid working medium is guided by the flow guide vane 4 to form a stable and continuous liquid film on the inner wall of the outer tube 21. Moreover, by arranging multiple groups of flow guide vanes 4, the liquid film on the inner wall of the outer tube 21 is divided into multiple regions; Meanwhile, the contact network 41 below the flow guide vane 4 adsorbs and adheres to the inner wall of the outer tube 21 through the magnetic beads 42, further guiding and attaching the working medium flowing down from the flow guide vane 4 to the inner wall of the outer tube 21 to form a continuous and stable liquid film. At the same time, when the working medium is guided by the contact network 41 to flow, the gaps on the contact network 41 will be blocked by the working medium and the flow rate of the working medium on the contact network 41 will be delayed, so that the contact network 41 and the working medium cooperate with each other to seal the gap between the flow guide vane 4 and the inner wall of the outer tube 21; Meanwhile, the inner tube 2 is divided into a steam channel 23 and a liquid channel 24, enabling both steam and liquid to pass through the inner tube 2 without interference. At the same time, the gap between the inner tube 2 and the outer tube 21 is only used to arrange the liquid film, for efficient evaporation and heat transfer. Meanwhile, the inner tube 2 is installed and limited in the outer tube 21 through the support 25; Meanwhile, since the gap between the inner tube 2 and the outer tube 21 is only used to arrange the liquid film, the gap between the inner tube 2 and the outer tube 21 can be arranged relatively small. Combined with the interception of the working medium by the baffle 3 in the liquid channel 24, the thickness and height of the liquid film arranged in the gap between the inner tube 2 and the outer tube 21 will be limited, that is, the number of liquid working media per unit length in the evaporation section is relatively small, avoiding the static pressure of the liquid film being too large due to the liquid film being too thick or too high; A secondary generator 54 is provided to exchange heat with the supercritical CO2 medium flowing in the secondary cycle when the condenser 52 cools and condenses the working medium, causing the temperature of the cycle working medium to rise and vaporize, so as to enter the turbine expander in the secondary generator 54 to perform work and generate electricity, and facilitating the cooling and condensation of the working medium in the condenser 52; Meanwhile, since the overall unit of the secondary cycle is located on the ground and the unit position is close to the condenser 52, the path of the secondary cycle is relatively short and completely enclosed, greatly improving the sealing performance of the pipeline in the secondary cycle and reducing the possibility of leakage of the cycle working medium; Since the length of the underground heat pipe 1 installed underground is relatively long, there is resistance when injecting the liquid working medium into the underground heat pipe 1, and there is a possibility of affecting the circulating flow of the working medium. At the same time, since the volume inside the medium storage tank 5 is fixed, by adjusting the pressure valve 53, part of the steam discharged from the underground heat pipe 1 enters the medium storage tank 5, increasing the pressure inside the medium storage tank 5, thereby reducing the difficulty of injecting the liquid working medium into the underground heat pipe 1 using the increased pressure and ensuring that the working medium can complete the cycle smoothly; Install a baffle plate 31 in the liquid channel 24 so that the liquid working medium injected into the liquid channel 24 by the liquid inlet pipe 12 will be blocked by the baffle plate 31, causing the liquid working medium to be close to the baffle 3 on the liquid channel 24, reducing the possibility of the liquid working medium splashing and spraying onto the partition plate 22 in the liquid channel 24, and relatively separating the liquid working medium from the steam in the inner tube 2 and increasing the distance between the two; At the same time, due to the blocking and guiding of the liquid working medium by the baffle plate 31, when reducing the injection amount of the working medium in the liquid channel 24, the liquid working medium can be smoothly intercepted and accumulated by the baffle 3, ensuring that the liquid working medium smoothly passes through the liquid hole 241, so that the liquid working medium does not need to completely fill the liquid channel 24, further reducing the heat exchange between the liquid working medium and the gaseous working medium in the inner tube 2; At the same time, by setting a micro-hole area 32 on the baffle 3, after the working medium accumulates between the baffle 3 and the inner wall of the liquid channel 24, the working medium will gradually reach the micro-hole area 32, and the working medium will pass through the micro-holes and fall onto the baffle 3 below. At the same time, after the working medium falls onto the baffle 3 below, the working medium will flow and accumulate along the surface of the baffle 3 until the working medium reaches the micro-hole area 32 on the baffle 3 below again. At the same time, through the conduction of the working medium by the micro-hole area 32, it is convenient for the working medium to flow between two adjacent upper and lower baffles 3, avoiding the situation that after the working medium overflows from the edge of the upper baffle 3, it is not easy to enter the lower baffle 3 and is likely to directly fall to the bottom of the underground heat pipe 1; By making the flow guide piece 4 of a bimetal or a shape memory metal, the gap between the flow guide piece 4 and the inner wall of the outer tube 21 increases with the increase of the external formation temperature, accelerating the quantity of the working medium flowing downward and increasing the thickness of the liquid film, ensuring the continuous and stable existence of the liquid film on the inner wall of the outer tube 21. At the same time, the heat-induced deformation of the heat conducting piece, combined with the increasing arrangement quantity of the flow guide piece 4 from top to bottom, further accelerates the working medium to enter the gap between the outer tube 21 and the inner tube 2; By setting multiple layers of reflective layers and heat insulation layers, the heat insulation effect of the heat insulation layer is improved, reducing the heat exchange between the liquid working medium and the gaseous working medium in the inner tube 2. At the same time, since the heat insulation layer is composed of multiple layers, the thermal resistance between the layers will be increased. At the same time, the reflective layer can be made of an aluminum foil layer, and the heat insulation layer is made of common heat insulation materials. At the same time, by installing the heat insulation layer on the inner wall of the inner tube 2, the heat insulation layer is in contact with the gaseous working medium in the steam channel 23, reducing the impact and friction on the heat insulation layer and avoiding the erosion of the heat insulation layer after contacting the liquid working medium; By providing a contact groove 211 on the inner wall of the outer tube 21, the contact area between the liquid working medium and the inner wall of the outer tube 21 is increased. At the same time, when the liquid working medium flows downward along the inner wall of the outer tube 21, it will be blocked by the contact groove 211, thereby prolonging the residence time of the liquid working medium on the inner wall of the outer tube 21; At the same time, the magnetic beads 42 and the contact groove 211 are mutually matched. After the magnetic beads 42 are adsorbed to the contact groove 211 under the action of magnetic force, the contact area between the magnetic beads 42 and the contact groove 211 is relatively large, that is, the adsorption stability of the magnetic beads 42 in the contact groove 211 is relatively high; By providing a fixing frame, a relatively large height difference is provided between the medium storage tank 5 and the ground. As a result, the liquid working medium in the medium storage tank 5 has a relatively large gravitational potential energy, which is convenient for the liquid working medium to be re-injected into the underground heat pipe 1, further ensuring that the working medium can smoothly perform self-circulation. At the same time, the pressure of the gaseous working medium injected into the medium storage tank 5 is reduced, and the influence on the geothermal energy conversion efficiency is reduced.

[0029] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the description in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A geothermal utilization generator set for underground use, characterized in that: It includes a subterranean heat pipe (1), a steam turbine generator (51), a condenser (52), and a medium storage tank (5) connected in sequence. The working medium in the subterranean heat pipe (1) absorbs heat and vaporizes, then enters the steam turbine generator (51) to do work and generate electricity. The working medium discharged from the steam turbine generator (51) enters the condenser (52), changes from gaseous state to liquid state, and then is stored in the medium storage tank (5). The working medium in the medium storage tank (5) flows back to the subterranean heat pipe (1) under the action of gravity. The subterranean heat pipe (1) includes an inner pipe (2) and an outer pipe (21). The space in the inner pipe (2) is divided into a steam channel (23) and a liquid channel (24) by a partition plate (22). The steam channel (23) is connected to the inlet of the steam turbine generator (51) through a steam outlet pipe (12), and the liquid channel (24) is communicated with the outlet of the medium storage tank (5) through a liquid inlet pipe (12). A deflector (4) with an inclined downward cross-section is installed on the outer wall of the inner pipe (2). There is a gap between the deflector (4) and the inner wall of the outer pipe (21). Liquid holes (241) and steam holes (231) are formed in the inner pipe (2). A baffle (3) with an inclined upward cross-section is installed in the liquid channel (24). The liquid holes (241), the baffle (3), the deflector (4), and the steam holes (231) are distributed from top to bottom on the inner pipe (2) and correspond to each other one by one. A contact network (41) is installed on the deflector (4). A magnetic bead (42) is connected in series at the lower end of the contact network (41), and the magnetic bead (42) is adsorbed and attached to the inner wall of the outer pipe (21).

2. The geothermal utilization generator set for underground use according to claim 1, wherein: It further includes a secondary generator (54), a circulation pump (56), a condenser (52), and a pressure tank (55) connected in sequence. The circulation of the working medium in the steam turbine generator (51) is a primary circulation, and the circulation of the working medium in the secondary generator (54) is a secondary circulation. Supercritical CO2 is used as the circulating working medium in the secondary circulation. The secondary circulation exchanges heat with the primary circulation at the condenser (52) to utilize the remaining waste heat of the primary circulation.

3. The geothermal utilization generator unit for underground use according to claim 1, characterized in that: The steam outlet pipe (11) is also communicated with the medium storage tank (5), and a pressure regulating valve (53) is installed on the pipeline between the steam outlet pipe (11) and the medium storage tank (5).

4. The geothermal utilization generator unit for underground use according to claim 1, wherein: A blocking plate (31) is installed in the liquid channel (24). The blocking plate (31) is in contact with the baffle (3). The central angle corresponding to the blocking plate (31) is smaller than the central angle corresponding to the baffle (3). The outlet of the liquid inlet pipe (12) is aligned with the position between the blocking plate (31) and the inner wall of the outer pipe (21). A microporous area (32) is arranged on the side of the baffle (3) facing the center line.

5. The geothermal utilization generator set for underground use according to claim 1, wherein: The subterranean heat pipe (1) includes an adiabatic section and an evaporation section. The evaporation section is located in the high-temperature underground formation. The deflector (4) is located in the evaporation section, and the distance between the deflectors (4) in the evaporation section gradually decreases from top to bottom. The deflector (4) is made of a bimetallic strip or a shape memory metal. After the deflector (4) is deformed by heat, the gap between the deflector (4) and the inner wall of the outer tube (21) increases.

6. The geothermal utilization power generation unit for underground use according to claim 1, characterized in that: An insulating layer is installed on the inner wall of the inner tube (2) and the surface of the partition plate (22). The insulating layer is composed of multiple reflective layers and heat insulating layers.

7. The geothermal utilization generator set for underground use according to claim 1, wherein: Contact grooves (211) are formed on the inner wall of the outer tube (21), and multiple groups of contact grooves (211) are uniformly arranged. The size of the contact groove (211) matches the size of the magnetic beads (42).

8. The geothermal utilization power generation unit for underground use according to claim 3, wherein: The medium storage tank (5) is installed above the ground through a fixing frame. Multiple groups of underground heat pipes (1) are installed underground. The position of the medium storage tank (5) makes the pipeline distance between the medium storage tank (5) and each underground heat pipe (1) the shortest.

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