A geothermal power generating unit for use in a well

Abstract

The application belongs to the technical field of geothermal power generation equipment, in particular to an underground geothermal utilization generator set, which comprises underground heat pipes, turbine generators, condensers and medium storage tanks connected in sequence; the underground heat pipes comprise inner pipes and outer pipes, the space in the inner pipes is divided into steam channels and liquid channels by partitions; guide vanes are installed on the inner pipes, gaps exist between the guide vanes and the inner walls of the outer pipes, liquid holes and steam holes are formed in the inner pipes, and baffles are installed in the liquid channels; contact nets are installed on the guide vanes, magnetic beads are connected to the lower ends of the contact nets, and the magnetic beads are adsorbed and attached to the inner walls of the outer pipes; the application has simple structure, reduces geothermal energy transmission loss, improves geothermal energy power generation utilization rate, improves the heat exchange performance of the underground heat pipes, ensures continuous and stable liquid film, enables the liquid film to be relatively segmented, thereby avoiding excessive static pressure and affecting evaporation heat exchange.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geothermal power generation equipment, in particular to an underground geothermal utilization generator set. BACKGROUND

[0002] Geothermal energy is a natural heat energy extracted from the crust, and a large amount of heat energy is stored in the molten lava inside the earth. Geothermal energy is a green low-carbon and recyclable renewable energy. In the case of energy shortage, the demand for rational development of geothermal resources becomes more and more important, such as using geothermal water for house heating, developing greenhouse agricultural planting and hot spring tourism, etc.

[0003] At present, geothermal power generation technologies mainly include dry steam power generation, expansion type steam power generation, double working medium cycle power generation and Kalina cycle power generation, etc.:

[0004] Among them, the dry steam power generation system has simple process, mature technology, safety and reliability, and the cycle efficiency can reach more than 20%, which is the main form of high-temperature geothermal field power generation;

[0005] The expansion type power generation technology has been widely used in the field of geothermal power generation, especially in medium and high temperature geothermal fields, and the cycle efficiency of the two-stage expansion system is about 15%-20%;

[0006] For medium and low temperature geothermal resources, double working medium cycle power generation technology is more suitable, which is composed of geothermal water system and low boiling point medium system, and the cycle efficiency can be increased by 20%-30% compared with expansion type steam power generation technology;

[0007] 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 Kalina cycle power generation technology is 20%-50% higher than that of Rankine cycle.

[0008] In the development and utilization process of low temperature geothermal resources, double working medium cycle and Kalina cycle technology have broad development prospects. The existing power generation equipment cannot well utilize geothermal resources when in use, and usually needs to first absorb and transmit the underground geothermal energy to the ground for power generation, which is easy to cause the loss of geothermal energy in the transmission process, reduce the utilization rate of geothermal energy, and thus lead to low power generation efficiency and waste of resources. At the same time, for the super-long gravity heat pipe used for collecting geothermal energy, when the length-diameter ratio of the evaporation section is large under the condition of ground temperature, there are phenomena such as uneven flow of condensate liquid, insufficient wetting of evaporation wall surface, and complete absorption of heat vaporization to return to the bottom of the liquid pool to form a cold pool. In addition, the evaporation section is too long, which may also cause the depth of the working medium in the heat pipe to be too deep. Under the action of excessive static pressure, the pressure of the working medium in the deep layer is higher than the saturated steam pressure under the corresponding ground temperature, which causes the working medium to be unable to vaporize, reduces the heat transfer efficiency, and thus limits the length of the gravity heat pipe and affects the heat transfer effect. SUMMARY

[0009] 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 exchange performance of the underground heat pipe, ensure the continuity and stability of the liquid film, make the liquid film relatively segmented, thereby avoiding excessive static pressure and affecting evaporation heat exchange, the application provides an underground geothermal utilization generator.

[0010] The technical scheme adopted by the application to solve the technical problems is that the underground geothermal utilization generator comprises an underground heat pipe, a turbine generator, a condenser and a medium storage tank connected in sequence.

[0011] The working medium in the underground heat pipe is vaporized after absorbing heat and enters the turbine generator to generate power, the working medium discharged from the turbine generator enters the condenser to change from a gaseous state to a liquid state and is then stored in the medium storage tank, and the working medium in the medium storage tank flows back to the underground heat pipe under the action of gravity.

[0012] The underground heat pipe comprises an inner pipe and an outer pipe, the space in the inner pipe is divided into a steam passage and a liquid passage by a partition plate, the steam passage is connected to the inlet of the turbine generator through a steam outlet pipe, and the liquid passage is connected to the outlet of the medium storage tank through a liquid inlet pipe.

[0013] The outer wall of the inner pipe is provided with a guide vane with an inclined downward cross section, there is a gap between the guide vane and the inner wall of the outer pipe, the inner pipe is provided with a liquid hole and a steam hole, the liquid passage is provided with a baffle with an inclined upward cross section, and the liquid hole, the baffle, the guide vane and the steam hole are distributed from top to bottom on the inner pipe and correspond to each other.

[0014] The guide vane is provided with a contact network, and the lower end of the contact network is connected with a magnetic bead, and the magnetic bead is adsorbed and attached to the inner wall of the outer pipe.

[0015] Preferably, a secondary generator, a circulating pump, a condenser and a pressure tank are connected in sequence, the cycle of the working medium in the turbine generator is a primary cycle, the cycle of the working medium in the secondary generator is a secondary cycle, and supercritical CO2 is used as the circulating working medium in the secondary cycle.

[0016] The secondary cycle and the primary cycle exchange heat at the condenser, and the remaining waste heat of the primary cycle is utilized.

[0017] Preferably, the steam outlet pipe is also connected to the medium storage tank, and a pressure regulating valve is installed on the pipeline between the steam outlet pipe and the medium storage tank.

[0018] 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, and the outlet of the liquid inlet pipe is aligned with the position between the blocking plate and the inner wall of the outer pipe.

[0019] The baffle is provided with a microporous area on the side facing the center line.

[0020] Preferably, the underground heat pipe comprises an adiabatic section and an evaporation section, the evaporation section is located in a high-temperature stratum underground, the guide vanes are located in the evaporation section, and the distance between the guide vanes in the evaporation section gradually decreases from top to bottom.

[0021] The guide vanes are made of bimetallic sheets or memory metals, and the guide vanes are deformed by heat to increase the gap between the guide vanes and the inner wall of the outer pipe.

[0022] Preferably, an adiabatic layer is installed on the inner wall of the inner pipe and the surface of the partition plate, and the adiabatic layer is composed of multiple reflection layers and thermal insulation layers.

[0023] Preferably, a contact groove is formed on the inner wall of the outer pipe, and multiple groups of the contact grooves are uniformly arranged.

[0024] The size of the contact groove is matched with the size of the magnetic beads.

[0025] Preferably, the medium storage tank is installed above the ground by a fixing frame, multiple underground heat pipes are installed underground, and the medium storage tank is located at a position such that the distance between the medium storage tank and the pipes of each underground heat pipe is the shortest.

[0026] The beneficial effects of the present application are as follows:

[0027] 1. The underground geothermal utilization generator set disclosed by the present application directly heats the working medium underground to generate steam, and then the steam directly drives the generator to generate electricity, thereby reducing the heat exchange times of the working medium, improving the utilization rate of geothermal energy, and avoiding affecting the balance of the underground water system without exploiting and recharging underground water during geothermal power generation.

[0028] 2. The underground geothermal utilization generator set disclosed by the present application isolates the gaseous and liquid working media from each other by arranging the guide vanes, the baffle, the blocking plate, the liquid channel and the steam channel, thereby avoiding mutual interference between the two, improving the heat exchange effect of the underground heat pipe and the utilization rate of geothermal energy, continuously and stably forming a liquid film on the inner wall of the outer pipe, improving the heat exchange performance of the underground heat pipe, and avoiding intermittent and blank liquid film on the inner wall of the outer pipe to affect the utilization of geothermal energy.

[0029] 3. The geothermal energy utilization generator set for underground wells described in this invention, by setting up a medium storage tank and a pressure valve, allows the medium storage tank to be installed at a high position via a fixing frame, giving the working medium inside the medium storage tank a large gravitational potential energy, facilitating the re-injection of the working medium into the underground heat pipe for self-circulation. At the same time, when the self-circulation of the working medium is not smooth, the pressure valve is adjusted to allow the gaseous working medium to enter the medium storage tank, increasing the pressure inside the medium storage tank, further increasing the pressure of the working medium injected into the underground heat pipe, ensuring the smooth self-circulation of the working medium without the need for additional energy to pump the working medium for circulation. Attached Figure Description

[0030] The invention will now be further described with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the generator set of the present invention;

[0032] Figure 2 This is a perspective view of the underground heat pipe in the generator set of the present invention;

[0033] Figure 3 This is a schematic diagram of the underground heat pipe structure in the generator set of the present invention;

[0034] Figure 4 This is a partial cross-sectional view of the underground heat pipe in the generator set of the present invention;

[0035] Figure 5 yes Figure 3 Enlarged view of a portion of point A in the middle;

[0036] Figure 6 yes Figure 4 Enlarged view of a section at point B in the middle;

[0037] In the diagram: underground heat pipe 1, steam outlet pipe 11, liquid inlet pipe 12, inner pipe 2, outer pipe 21, contact groove 211, baffle 22, steam passage 23, steam hole 231, liquid passage 24, liquid hole 241, support 25, baffle 3, barrier plate 31, microporous area 32, guide plate 4, contact wire 41, magnetic bead 42, medium storage tank 5, turbine generator 51, condenser 52, pressure valve 53, secondary generator 54, pressure tank 55, circulating pump 56. Detailed Implementation

[0038] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0039] like Figures 1 to 6 As shown, the geothermal utilization generator set for underground wells according to the present invention includes an underground heat pipe 1, a turbine generator 51, a condenser 52, and a medium storage tank 5 connected in sequence.

[0040] The working medium in the underground heat pipe 1 absorbs heat and vaporizes to enter the turbine generator 51 to do work and generate electricity, the working medium discharged from the turbine generator 51 enters the condenser 52 to change from gaseous state to liquid state and then is stored in the medium storage tank 5, and the working medium in the medium storage tank 5 returns to the underground heat pipe 1 under the action of gravity;

[0041] The underground heat pipe 1 comprises an inner pipe 2 and an outer pipe 21, the space in the inner pipe 2 is divided into a steam passage 23 and a liquid passage 24 by a partition plate 22, the steam passage 23 is connected to the inlet of the turbine generator 51 through the steam outlet pipe 12, and the liquid passage 24 is communicated to the outlet of the medium storage tank 5 through the liquid inlet pipe 12;

[0042] The outer wall of the inner pipe 2 is provided with a guide vane 4 with an inclined downward cross section, there is a gap between the guide vane 4 and the inner wall of the outer pipe 21, the inner pipe 2 is provided with a liquid hole 241 and a steam hole 231, the liquid passage 24 is provided with a baffle 3 with an inclined upward cross section, the liquid hole 241, the baffle 3, the guide vane 4 and the steam hole 231 are distributed from top to bottom on the inner pipe 2 and correspond to each other one by one;

[0043] The guide vane 4 is provided with a contact network 41, the lower end of the contact network 41 is connected with a magnetic bead 42, and the magnetic bead 42 is adsorbed and attached to the inner wall of the outer pipe 21;

[0044] The underground heat pipe 1 is installed into the well, heat exchange is performed between the underground heat pipe 1 and the high-temperature stratum underground, the low-boiling-point organic medium in the underground heat pipe 1 absorbs the heat underground to change from liquid state to gaseous state, then the vaporized working medium enters the turbine generator 51 to do work and generate electricity, then the working medium enters the condenser 52 to exchange heat, so that the working medium changes from gaseous state to liquid state, and the liquid working medium enters the medium storage tank 5, then the liquid working medium in the medium storage tank 5 reenters the underground heat pipe 1 under the action of gravity, to complete the self-circulation of the working medium, without using additional energy to drive the fluid in the system, at the same time, the working medium absorbs heat and vaporizes in the underground heat pipe 1 to directly drive the turbine generator 51 to do work and generate electricity, avoiding heat loss caused by heat transfer between multiple media, improving the geothermal utilization efficiency, and without exploiting and reinjecting underground water in the process of geothermal power generation, without affecting the balance of the underground water system;

[0045] Meanwhile, after the liquid working medium enters the liquid channel 24, the working medium will be intercepted by the baffle 3 as the working medium drops, and then the working medium will flow from the liquid hole 241 to the guide vane 4, so that the working medium flows along the guide of the 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, thereby facilitating the heat exchange of the liquid film with the heat in the outer tube 21 and the formation of gaseous working medium, and 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 outside the underground heat pipe 1;

[0046] Meanwhile, since the amount of working medium intercepted by the baffle 3 per unit time is greater than the amount of 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, which seals the liquid hole 241, preventing the steam after the working medium absorbs heat and vaporizes from entering the liquid channel 24 in the opposite direction. Meanwhile, as the accumulated liquid layer gradually increases, the liquid layer will overflow from the edge of the baffle 3 and be intercepted again by the baffle 3 below;

[0047] Meanwhile, by guiding the liquid working medium through the guide vane 4, a stable and continuous liquid film is formed on the inner wall of the outer tube 21, and by arranging multiple groups of guide vanes 4, the liquid film on the inner wall of the outer tube 21 is divided into multiple regions, thereby strengthening the heat transfer of the underground heat pipe 1 and improving the efficiency of geothermal energy utilization, 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;

[0048] Meanwhile, the contact network 41 below the guide vane 4 is adsorbed and attached to the inner wall of the outer tube 21 through the magnetic beads 42, further guiding the working medium flowing down the guide vane 4 to the inner wall of the outer tube 21, thereby forming a continuous and stable liquid film. Meanwhile, when the working medium is guided to flow by the contact network 41, the gaps on the contact network 41 will be blocked by the working medium and the flow speed of the working medium on the contact network 41 will be slowed down, so that the contact network 41 and the working medium cooperate to seal the gap between the guide vane 4 and the inner wall of the outer tube 21, preventing the steam after the working medium absorbs heat and vaporizes from flowing upward from the gap between the guide vane 4 and the inner wall of the outer tube 21, affecting the normal flow of the steam in the underground heat pipe 1 and the heat exchange efficiency of the underground heat pipe 1;

[0049] Meanwhile, the inner tube 2 is divided into a steam passage 23 and a liquid passage 24, so that the steam and the liquid pass through the inner tube 2 without interfering with each other, the intense heat exchange between the steam and the liquid is avoided, the heat transfer capacity of the underground heat pipe 1 is weakened, and the use of the underground heat pipe 1 in the super-long distance is restricted, meanwhile, the gap between the inner tube 2 and the outer tube 21 is only used to arrange the liquid film, the high-efficiency evaporation and the heat transfer, the heat exchange efficiency and the utilization rate of the underground heat pipe 1 for the geothermal energy are improved, meanwhile, the inner tube 2 is installed and limited in the outer tube 21 through the support 25;

[0050] Meanwhile, the gap between the inner tube 2 and the outer tube 21 is relatively small because the gap is only used to arrange the liquid film, and the liquid film thickness and height arranged in the gap between the inner tube 2 and the outer tube 21 are limited by the interception of the baffle 3 on the working medium in the liquid passage 24, that is, the number of the liquid working medium in the unit length in the evaporation section is relatively small, the liquid film is prevented from being too thick and high, the static pressure of the liquid film is prevented from being too large, the heat absorption vaporization and boiling process of the liquid working medium is affected, and the evaporation heat exchange efficiency is affected.

[0051] As an embodiment of the present application, the secondary generator 54, the circulating pump 56, the condenser 52 and the pressure tank 55 connected in sequence are further included, the circulation of the working medium in the turbine generator 51 is a primary circulation, the circulation of the working medium in the secondary generator 54 is a secondary circulation, and supercritical CO2 is used as the circulating working medium in the secondary circulation;

[0052] The secondary circulation and the primary circulation exchange heat at the condenser 52, and the residual waste heat of the primary circulation is utilized.

[0053] After the working medium in the underground heat pipe 1 enters the turbine generator 51 to do work and generate electricity, the working medium discharged from the turbine generator 51 still has some residual heat, at this time, the working medium is directly cooled and condensed through the condenser 52, the residual heat in the working medium is wasted, and the energy consumed by the condenser 52 in the condensation process is increased, therefore, the secondary generator 54 is arranged, the supercritical CO2 medium in the secondary circulation is heat-exchanged when the working medium is cooled and condensed by the condenser 52, the circulating working medium is raised in temperature and vaporized, and then enters the turbine expander in the secondary generator 54 to do work and generate electricity, the utilization rate of the geothermal energy is improved, the cooling and condensation of the working medium in the condenser 52 is facilitated, and the additional energy consumption is reduced.

[0054] Meanwhile, the whole unit of the secondary circulation is located on the ground, and the unit is close to the condenser 52, so that the path of the secondary circulation is relatively short and completely closed, the sealing performance of the pipeline in the secondary circulation is greatly improved, and the possibility of leakage of the circulating working medium is reduced.

[0055] As an embodiment of the present application, the steam outlet pipe 11 is also connected to the medium storage tank 5, and a pressure regulating valve 53 is installed on the pipe between the steam outlet pipe 11 and the medium storage tank 5;

[0056] Since the underground heat pipe 1 is relatively long, there is resistance when the liquid working medium is injected into the underground heat pipe 1, and there is a possibility of affecting the circulation 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 reducing the difficulty of injecting the liquid working medium into the underground heat pipe 1 by using the increased pressure, ensuring that the working medium can complete the circulation smoothly, and avoiding or reducing the input of additional energy to pump the working medium for circulation.

[0057] As an embodiment of the present application, a blocking plate 31 is installed in the liquid passage 24, the blocking plate 31 is in contact with the baffle 3, the corresponding central angle of the blocking plate 31 is smaller than that of 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;

[0058] The baffle 3 is provided with a microporous area 32 on the side facing the center line;

[0059] Since both gaseous and liquid working media pass through the inner pipe 2, although there is no direct contact between them, heat exchange between them is inevitable. Therefore, in order to improve the heat exchange efficiency of the underground heat pipe 1, it is necessary to make the two media far away from each other in the inner pipe 2, and to avoid or reduce heat exchange between them as much as possible. In this case, the blocking plate 31 is installed in the liquid passage 24, so that the liquid working medium injected into the liquid passage 24 by the liquid inlet pipe 12 is blocked by the blocking plate 31, making the liquid working medium close to the baffle 3 on the liquid passage 24, reducing the possibility of splashing or spraying of the liquid working medium in the liquid passage 24 onto the partition plate 22, thereby relatively far away from the steam in the inner pipe 2, increasing the distance between them, and reducing the heat exchange between them;

[0060] At the same time, due to the blocking and guiding of the blocking plate 31 to the liquid working medium, the liquid working medium can be smoothly intercepted and stored by the baffle 3 under the condition of reducing the injection amount of the working medium in the liquid passage 24, so as to ensure that the liquid working medium can pass through the liquid hole 241 smoothly, thereby making the liquid working medium not need to completely fill the liquid passage 24, further reducing the heat exchange between the liquid working medium and the gaseous working medium in the inner pipe 2, and improving the heat exchange efficiency and effect of the underground heat pipe 1;

[0061] Meanwhile, by setting the micro-hole area 32 on the baffle 3, after the working medium is accumulated between the baffle 3 and the inner wall of the liquid channel 24, the working medium gradually reaches the micro-hole area 32, so that the working medium passes through the micro-hole and falls on the lower baffle 3, and after the working medium falls on the lower baffle 3, the working medium flows and accumulates on the surface of the baffle 3 until the working medium reaches the micro-hole area 32 on the lower baffle 3 again. By the conduction of the working medium through the micro-hole area 32, the working medium can flow between the adjacent upper and lower baffles 3, so that the working medium does not easily overflow from the edge of the upper baffle 3 and directly fall to the bottom of the underground heat pipe 1, thereby affecting the arrangement of the liquid film on the inner wall of the outer pipe 21 in the underground heat pipe 1 and the heat exchange performance of the underground heat pipe 1.

[0062] As an embodiment of the present application, the underground heat pipe 1 comprises an adiabatic section and an evaporation section, the evaporation section is located in a high-temperature stratum underground, and the guide vanes 4 are located in the evaporation section, and the distance between the guide vanes 4 in the evaporation section gradually decreases from top to bottom.

[0063] The guide vanes 4 are made of bimetallic sheets or memory metal, and the deformation of the guide vanes 4 caused by heat increases the gap between the guide vanes 4 and the inner wall of the outer pipe 21.

[0064] Since the temperature of the underground gradually increases with the increase of the depth, and the length of the evaporation section of the underground heat pipe 1 is relatively long, the temperature of the lower end of the evaporation section is relatively high, which intensifies the boiling phenomenon of the liquid film on the inner wall of the outer pipe 21 near the lower end of the evaporation section, and accelerates the heat absorption and vaporization speed of the liquid film. Therefore, by making the guide vanes 4 of bimetallic sheets or memory metal, the gap between the guide vanes 4 and the inner wall of the outer pipe 21 increases with the increase of the temperature of the surrounding stratum, thereby increasing the amount of downward flow of the working medium and the thickness of the liquid film, ensuring the continuous and stable existence of the liquid film on the inner wall of the outer pipe 21, and improving the heat transfer capacity of the underground heat pipe 1. Meanwhile, the deformation of the heat-conducting sheet, combined with the increase of the number of guide vanes 4 arranged from top to bottom, further accelerates the working medium entering the gap between the outer pipe 21 and the inner pipe 2, ensures the stability and continuity of the liquid film on the inner wall of the outer pipe 21, and improves the heat exchange performance of the underground heat pipe 1.

[0065] As an embodiment of the present application, an adiabatic layer is installed on the inner wall of the inner pipe 2 and the surface of the partition plate 22, and the adiabatic layer is composed of multiple reflection layers and thermal insulation layers.

[0066] By setting the multi-layer reflective layer, the heat insulation layer, the heat insulation effect of the heat insulation layer on heat is improved, the heat exchange between the liquid working medium and the gaseous working medium in the inner tube 2 is reduced, and the utilization rate of geothermal energy is improved. Meanwhile, the heat insulation layer is composed of multiple layers, which increases the thermal resistance between the layers and improves the heat insulation effect. Meanwhile, the reflective layer can be made of aluminum foil layer and heat insulation layer, which are common heat insulation materials. Meanwhile, 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 passage 23, which reduces the impact and friction on the heat insulation layer and avoids the impact of the liquid working medium on the heat insulation layer, thereby prolonging the service life of the heat insulation layer.

[0067] As an embodiment of the present application, a plurality of contact grooves 211 are arranged on the inner wall of the outer tube 21.

[0068] The size of the contact groove 211 is matched with the size of the magnetic beads 42.

[0069] By arranging 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. Meanwhile, when the liquid working medium flows downward along the inner wall of the outer tube 21, it is blocked by the contact grooves 211, thereby prolonging the residence time of the liquid working medium on the inner wall of the outer tube 21 and improving the evaporation heat exchange efficiency, thereby improving the heat exchange performance of the underground heat pipe 1.

[0070] Meanwhile, the magnetic beads 42 and the contact grooves 211 are matched with each other, so that when the magnetic beads 42 are adsorbed to the contact grooves 211 under the action of the magnetic force, the contact area between the magnetic beads 42 and the contact grooves 211 is relatively large, that is, the stability of the magnetic beads 42 adsorbed in the contact grooves 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 break the contact between the contact net 41 and the inner wall of the outer tube 21, thereby affecting the guidance of the contact net 41 to the working medium.

[0071] As an embodiment of the present application, the medium storage tank 5 is installed above the ground by a fixing frame, a plurality of underground heat pipes 1 are installed underground, and the medium storage tank 5 is located at a position where the distance between the medium storage tank 5 and the pipelines of each underground heat pipe 1 is the shortest.

[0072] By arranging the fixing frame, a relatively large height difference is formed between the medium storage tank 5 and the ground, so that the liquid working medium in the medium storage tank 5 has a large gravitational potential energy, which facilitates the re-injection of the liquid working medium into the underground heat pipe 1, further ensures the smooth self-circulation of the working medium, avoids the consumption of additional energy, and reduces the pressure of the gaseous working medium injected into the medium storage tank 5, thereby reducing the influence on the geothermal energy conversion efficiency.

[0073] The specific working process is as follows:

[0074] The underground heat pipe 1 is installed into the well, the low-boiling organic medium in the underground heat pipe 1 is converted from liquid state to gaseous state, then enters the turbine generator 51 to do work and generate electricity, then the working medium enters the condenser 52 to exchange heat, and the working medium converted to liquid state enters the medium storage tank 5, then the liquid working medium in the medium storage tank 5 reenters the underground heat pipe 1 by gravity, completing the self-circulation of the working medium;

[0075] Meanwhile, after the liquid working medium enters the liquid channel 24, the working medium is intercepted by the baffle 3 as it descends, then the working medium flows from the liquid hole 241 to the guide vane 4, flows to the inner wall of the outer pipe 21 guided by the guide vane 4, and forms a liquid film on the inner wall of the outer pipe 21, exchanges heat and vaporizes to generate gaseous working medium, then the gaseous working medium enters the steam channel 23 from the steam hole 231 and is discharged from the steam outlet pipe 11;

[0076] Meanwhile, the amount of working medium intercepted by the baffle 3 per unit time is greater than the amount of working medium allowed to pass through the liquid hole 241 per unit time, so that 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 close the liquid hole 241, and when the accumulated liquid layer gradually increases, the liquid layer will overflow from the edge of the baffle 3 and be intercepted again by the baffle 3 below;

[0077] Meanwhile, the guide vane 4 guides the liquid working medium to form a stable and continuous liquid film on the inner wall of the outer pipe 21, and the liquid film on the inner wall of the outer pipe 21 is divided into multiple regions by multiple sets of guide vanes 4;

[0078] Meanwhile, the contact network 41 below the guide vane 4 is adsorbed and close to the inner wall of the outer pipe 21 by the magnetic beads 42, further guiding the working medium flowing down the guide vane 4 to adhere to the inner wall of the outer pipe 21 to form a continuous and stable liquid film, and when the working medium is guided to flow by the contact network 41, the gap in the contact network 41 is blocked by the working medium and the flow speed of the working medium on the contact network 41 is slowed down, so that the contact network 41 and the working medium cooperate to close the gap between the guide vane 4 and the inner wall of the outer pipe 21;

[0079] Meanwhile, the inner pipe 2 is divided into the steam channel 23 and the liquid channel 24, so that the steam and the liquid pass through the inner pipe 2 without interfering with each other, and the gap between the inner pipe 2 and the outer pipe 21 is only used to arrange the liquid film, efficient evaporation and heat transfer, and the inner pipe 2 is installed and limited in the outer pipe 21 by the bracket 25;

[0080] At the same time, 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 relatively small, and the interception of the working medium by the baffle 3 in the liquid channel 24 is matched, so that 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 amount of liquid working medium per unit length in the evaporation section is relatively small, avoiding the liquid film being too thick and high, which causes the static pressure of the liquid film to be too large;

[0081] The secondary generator 54 is arranged, and when the condenser 52 cools and condenses the working medium, the supercritical CO2 medium flowing in the secondary cycle is heat-exchanged to increase the temperature and vaporize the circulating working medium, so that the circulating working medium enters the turbine expander in the secondary generator 54 to do work and generate electricity, and facilitates the cooling and condensation of the working medium in the condenser 52;

[0082] At the same time, since the overall unit of the secondary cycle is located on the ground, and the unit is close to the condenser 52, the path of the secondary cycle is relatively short and completely closed, which greatly improves the sealing performance of the pipeline in the secondary cycle and reduces the possibility of leakage of the circulating working medium;

[0083] Since the underground heat pipe 1 installed underground has a relatively long length, there is resistance when the liquid working medium is injected into the underground heat pipe 1, which may affect the circulation 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 reducing the difficulty of injecting the liquid working medium into the underground heat pipe 1 by using the increased pressure, and ensuring that the working medium can complete the circulation smoothly;

[0084] The blocking plate 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 is blocked by the blocking plate 31, so that the liquid working medium is close to the baffle 3 on the liquid channel 24, reducing the possibility of splashing and spraying of the liquid working medium in the liquid channel 24 to the partition plate 22, and relatively far away from the steam in the inner tube 2, increasing the distance between them;

[0085] At the same time, due to the blocking and guiding of the liquid working medium by the blocking plate 31, the liquid working medium can be smoothly intercepted and stored by the baffle 3 under the condition of reducing the injection amount of the working medium in the liquid channel 24, so as to ensure that the liquid working medium passes through the liquid hole 241 smoothly, thereby making the liquid working medium not need to completely fill the liquid channel 24, and further reducing the heat exchange between the liquid working medium and the gaseous working medium in the inner tube 2;

[0086] Meanwhile, by setting the micro-hole area 32 on the baffle 3, after the working medium is accumulated between the baffle 3 and the inner wall of the liquid channel 24, the working medium will gradually reach the micro-hole area 32, so that the working medium passes through the micro-hole and falls on the lower baffle 3, and after the working medium falls on the lower baffle 3, 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 lower baffle 3 again. By the conduction of the micro-hole area 32 to the working medium, the working medium can flow between the adjacent upper and lower baffles 3, and the working medium is not easy to enter the lower baffle 3 from the edge of the upper baffle 3 and directly fall to the bottom of the underground heat pipe 1.

[0087] The flow guide piece 4 is made of a bimetallic strip or a memory metal, so that the gap between the flow guide piece 4 and the inner wall of the outer pipe 21 increases with the increase of the temperature of the external formation, which accelerates the amount of working medium flowing downward and increases the thickness of the liquid film, ensuring the continuous and stable existence of the liquid film on the inner wall of the outer pipe 21. Meanwhile, the thermal deformation of the heat-conducting piece, combined with the increased number of flow guide pieces 4 arranged from top to bottom, further accelerates the working medium entering the gap between the outer pipe 21 and the inner pipe 2.

[0088] By setting multiple reflection layers and thermal insulation layers, the heat insulation effect of the heat insulation layer is improved, and the heat exchange between the liquid working medium and the gaseous working medium in the inner pipe 2 is reduced. Meanwhile, the heat insulation layer is composed of multiple layers, which increases the thermal resistance between the layers. Meanwhile, the reflection layer can be made of aluminum foil and common thermal insulation materials. By installing the heat insulation layer on the inner wall of the inner pipe 2, the heat insulation layer is in contact with the gaseous working medium in the vapor channel 23, which reduces the impact and friction on the heat insulation layer and avoids the erosion of the heat insulation layer when it comes into contact with the liquid working medium.

[0089] By opening the contact groove 211 on the inner wall of the outer pipe 21, the contact area between the liquid working medium and the inner wall of the outer pipe 21 is increased. Meanwhile, when the liquid working medium flows downward along the inner wall of the outer pipe 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 pipe 21.

[0090] Meanwhile, the magnetic beads 42 and the contact groove 211 are matched with each other, so that the magnetic beads 42 are adsorbed to the contact groove 211 under the action of magnetic force, and the contact area between the magnetic beads 42 and the contact groove 211 is relatively large, that is, the stability of the magnetic beads 42 adsorbed in the contact groove 211 is relatively high.

[0091] By setting the fixing frame, the medium storage tank 5 and the ground exist relatively large height difference, and then the liquid working medium in the medium storage tank 5 has relatively large gravitational potential energy, so that the liquid working medium is re-injected into the underground heat pipe 1, further ensure that the working medium can be smoothly self-circulation, at the same time, reduce the pressure of gaseous working medium injected into the medium storage tank 5, reduce the influence on the geothermal energy conversion efficiency.

[0092] The basic principle, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principle of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A geothermal energy utilization generator set for underground wells, characterized in that: It includes a ground heat pipe (1), a turbine generator (51), a condenser (52), and a medium storage tank (5) connected in sequence; The working medium in the underground heat pipe (1) absorbs heat and vaporizes before entering the turbine generator (51) to generate electricity. The working medium discharged from the turbine generator (51) enters the condenser (52) and changes from gaseous to liquid before being stored in the medium storage tank (5). The working medium in the medium storage tank (5) flows back into 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 passage (23) and a liquid passage (24) by a partition (22). The steam passage (23) is connected to the inlet of the turbine generator (51) through a steam outlet pipe (11), and the liquid passage (24) is connected to the outlet of the medium storage tank (5) through a liquid inlet pipe (12). The inner tube (2) is equipped with a guide vane (4) with an inclined downward cross section. There is a gap between the guide vane (4) and the inner wall of the outer tube (21). The inner tube (2) is provided with a liquid hole (241) and a steam hole (231). The liquid channel (24) is equipped with a baffle (3) with an inclined upward cross section. The liquid hole (241), baffle (3), guide vane (4), and steam hole (231) are distributed from top to bottom on the inner tube (2) and correspond to each other one by one. A contact wire (41) is installed on the guide plate (4), and a magnetic bead (42) is connected in series at the lower end of the contact wire (41). The magnetic bead (42) is adsorbed and attached to the inner wall of the outer tube (21).

2. The geothermal power generation unit for downhole utilization according to claim 1, characterized in that: It also includes a secondary generator (54), a circulating pump (56), a condenser (52), and a pressure tank (55) connected in sequence. The circulation of the working medium in the 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 cycle exchanges heat with the primary cycle at the condenser (52), utilizing the residual heat from the primary cycle.

3. The geothermal utilization generator set for underground wells according to claim 1, characterized in that: 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).

4. A geothermal power generation unit for downhole utilization according to claim 1, characterized in that: A baffle plate (31) is installed in the liquid channel (24). The baffle plate (31) and the baffle (3) are in contact with each other. The central angle of the baffle plate (31) is smaller than the central angle of the baffle (3). The outlet of the liquid inlet pipe (12) is aligned with the position between the baffle plate (31) and the inner wall of the outer pipe (21). The baffle (3) has a microporous area (32) on the side facing the center line.

5. A geothermal power generation unit for downhole utilization according to claim 1, characterized in that: The underground heat pipe (1) includes an insulation section and an evaporation section. The evaporation section is located in a high-temperature underground stratum. The guide vanes (4) are located in the evaporation section. The distance between the guide vanes (4) in the evaporation section gradually decreases from top to bottom. The guide plate (4) is made of bimetallic strip or shape memory metal. After the guide plate (4) is deformed by heat, the gap between the guide plate (4) and the inner wall of the outer tube (21) increases.

6. A geothermal power generation unit for downhole utilization according to claim 1, characterized in that: The inner wall of the inner tube (2) and the surface of the partition (22) are equipped with an insulation layer, which is composed of multiple reflective layers and insulation layers.

7. A geothermal power generation unit for downhole utilization according to claim 1, characterized in that: The inner wall of the outer tube (21) is provided with a contact groove (211), and multiple sets of the contact groove (211) are evenly arranged. The size of the contact groove (211) is matched with the size of the magnetic bead (42).

8. A geothermal power generation unit for downhole utilization according to claim 3, characterized in that: The medium storage tank (5) is installed above the ground by a fixing frame. Multiple sets of underground heat pipes (1) are installed in the well. The location of the medium storage tank (5) minimizes the pipe distance between the medium storage tank (5) and each underground heat pipe (1).

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