JP7269674B2 - Geothermal power generation system - Google Patents

Description

In the present invention, heat is recovered by a medium using a geotropical heat source as a heat source, and when the heat medium is transferred, a heat medium transfer pipe with an enhanced ability to retain heat, and the heat medium transfer pipe is used to generate power. It relates to a geothermal power generation system and a geothermal power generation method.

Geothermal power generation systems have traditionally extracted natural steam existing in the geotropics using natural pressure and separated it from water. contains a large amount of impurities. This impurity becomes scale and adheres to thermal wells, pipes, turbine blades, and the like. When scale adheres, the amount of power generated decreases over time, making long-term use difficult.

In Patent Document 1, in a binary power generation system, a closed-loop circulation flow path is provided in which a heat source fluid absorbs heat through heat exchange with a geothermal fluid or geothermal heat, releases heat in an evaporator, and circulates again for heat exchange with the geothermal fluid or geothermal heat. In addition, for the cooling fluid that cools the low boiling point medium, either a closed loop flow path is configured in the ground for heat radiation cooling, or the heat source fluid after passing through the evaporator is used as the driving heat source. A geothermal power generation system has been proposed that comprises a closed loop flow path that controls the temperature of the cooling fluid and supplies the cooling fluid to the condenser so that the condensing of the low boiling point medium in the condenser can be optimized.

Patent Literature 2 discloses a general pipe threaded joint used for a heat medium transfer pipe that efficiently recovers the heat medium, and includes a pin and a contact surface each having a threaded portion and an unthreaded metal contact portion. The unthreaded metal contact portion comprises a box, wherein the unthreaded metal contact portion has a sealing surface and a shoulder surface, the shoulder surface of the pin is located on the end surface of the tip of the pin, and the pin and the box do not contact each other between the sealing surface and the shoulder surface. A threaded joint for pipes is described which has a non-contact area and the shoulder surface of at least one of the pin and box has at least one groove leading to said non-contact area and the interior of the threaded joint.

JP 2014-84857 A Japanese translation of PCT publication No. 2014-517925

As described above, in the power generation method that pumps up and utilizes hot spring water, scale adheres to facilities such as geothermal wells and production wells, as well as piping facilities and turbines, resulting in a decrease in the amount of power generation over time. Also, regular maintenance is required to remove scale. In terms of the environment as well, since the hot spring water is pumped up and used, it is conceivable that the amount of discharge of the hot spring water will be affected. In addition, after hot spring water is pumped up and used for power generation, the water is returned to the earth from the return well, but it contains chemical substances for removing scale and has a considerable impact on the environment.
In addition, as seen in Patent Document 1, the method of generating power using only underground heat is effective because it is environmentally friendly and there is no need to consider the amount of hot spring water, chemical substances, and the like.

In addition, a heat medium transfer pipe is required to recover heat underground and transfer the obtained hot water to the ground, and the heat medium transfer pipe depends on the temperature of the geotropical zone A length of 1000m to 3000m is required, and the heat medium transfer pipe is connected by a pipe screw joint, and the heat medium transfer pipe extends deep into the ground. As seen in Patent Document 2, threaded joints for pipes are strongly required to have compression resistance performance and sealing performance under internal and external pressures, and are firmly joined to pipes.

However, pipe screw joints do not have a structure to improve heat retention performance, and heat transfer occurs between the inside and outside of the pipe near the ground surface where the temperature is low, and the heat recovered from the ground is taken away. There's a problem. In addition to threaded joints for pipes, the larger the diameter of transfer pipes that require heat insulation, the more difficult the heat insulation structure is due to the balance between strength and technical difficulty. There is also a demand for a technique for improving the workability of installation without impairing the heat insulating performance by providing a heat insulating structure.
Therefore, in order to effectively use the heat medium obtained from the ground, it is transferred to the separator or heat exchanger on the ground without losing the heat of the heat medium during the transfer while considering the work performance. technology has become necessary.

The present invention has been made in view of such problems, and in order to effectively utilize the heat obtained from the geotropical zone by the medium on the ground, pressure is applied in the heat medium transfer pipe to prevent boiling, and the heat is To provide a geothermal power generation system capable of efficiently absorbing heat from a geothermal zone by circulating water in a heat medium transfer pipe as a single-phase flow, compared with the case of circulating as a gas-liquid two-phase flow. With the goal.

In order to achieve the above object, the present invention employs the following means.

A geothermal power generation system that includes a plurality of heat medium transfer pipes that convey a medium underground and recover the medium that has absorbed heat in the ground, and generates power using the heat of the recovered medium,
In order to circulate the medium in the heat medium transfer pipe, a switching valve for switching the flow path of the medium, and pressure adjustment means for circulating the medium while maintaining the pressure at a predetermined pressure without changing the state of the medium. and
When the temperature of the medium drops, the switching valve and the pressure adjusting means are driven to circulate the medium in the heat medium transfer pipe until the temperature of the medium recovers.

According to the above features, the present invention circulates as a gas-liquid two-phase flow by applying pressure in the heat medium transfer pipe to prevent boiling and circulating the hot water in the heat medium transfer pipe as a single-phase flow. It is possible to absorb heat from the geotropic U more efficiently than the

FIG. 1 is a schematic diagram showing the configuration of the geothermal power generation system of the present invention according to the first embodiment. FIG. 2 is a perspective view showing part of the heat medium transfer pipe of the present invention according to the first embodiment. FIG. 3 is a partially exploded perspective view of the medium injection tube of the present invention according to the first embodiment. FIG. 4 is a longitudinal sectional view of part of the medium injection tube of the present invention according to the first embodiment. FIG. 5 is a perspective view of part of the heat insulating tube of the present invention according to the first embodiment. FIG. 6 is a longitudinal sectional view of part of the medium injection tube of the present invention according to the first embodiment. FIG. 7 is a longitudinal sectional view of part of the heat medium transfer pipe of the present invention according to the first embodiment. FIG. 8 is a longitudinal sectional view of part of the heat medium take-out pipe of the present invention according to the first embodiment. FIG. 9 is a schematic diagram of the water state change of the present invention according to the first embodiment. FIG. 10 is a relationship diagram showing the relationship between the depth of the heat medium transfer pipe and the temperature distribution of hot water in the geothermal power generation system of the present invention according to the first embodiment. 11A and 11B are explanatory diagrams related to experimental data showing heat retention performance of the present invention according to the first embodiment. FIG. FIG. 12 is a schematic diagram showing the configuration of the geothermal power generation system of the present invention according to the second embodiment. FIG. 13 is a schematic diagram showing the configuration of the geothermal power generation system of the present invention according to the third embodiment. FIG. 14 is a schematic diagram showing the configuration of the geothermal power generation system of the present invention according to the fourth embodiment. FIG. 15 is a vertical cross-sectional view with a part omitted of the heat medium transfer pipe of the present invention according to the fifth embodiment. FIG. 16 is a vertical cross-sectional view in the middle of constructing the heat medium transfer pipe of the present invention according to the fifth embodiment. FIG. 17 is a vertical cross-sectional view in the middle of constructing the heat medium transfer pipe of the present invention according to the fifth embodiment. FIG. 18 is an enlarged schematic diagram of a pipe screw joint of the heat medium transfer pipe of the present invention according to the fifth embodiment. FIG. 19 is a vertical cross-sectional view with a part omitted of a heat medium transfer pipe of a modification of the present invention according to the fifth embodiment. FIG. 20 is a relational diagram showing the relationship between the depth of the heat medium transfer pipe and the temperature distribution of hot water in the geothermal power generation system of the present invention according to the fifth embodiment. FIG. 21 is a schematic diagram showing the configuration of the geothermal power generation system of the present invention according to the sixth embodiment. FIG. 22 is a schematic diagram showing the configuration of the heat medium transfer pipe of the present invention according to the sixth embodiment. 23 is a longitudinal sectional view showing a modification of the heat medium take-out pipe according to the first embodiment; FIG. FIG. 24 is a schematic diagram showing a modification of the receiving tube according to the fifth embodiment;

Embodiments of geothermal power generation systems 1, 100, 200, 300, and 400 according to the present invention will be described in detail with reference to the drawings. It should be noted that the embodiments and drawings described below illustrate a part of the embodiments of the present invention, and are not used for the purpose of limiting to these configurations, and are within the scope of the present invention. can be changed as appropriate. Corresponding components in each figure are labeled with the same or similar reference numerals.

(First embodiment)
A geothermal power generation system 1 according to a first embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram showing the configuration of a geothermal power generation system 1 of the present invention according to a first embodiment.

The geothermal power generation system 1 mainly includes a pressurized water supply pump 3, a heat medium transfer pipe 10, a hot water service tank 4, a condensing unit 17, a water supply unit 18, a steam separator F, a steam turbine T, a generator G, and power receiving equipment. TF.
The geothermal power generation system 1 heat-exchanges water as a medium supplied from the pressurized water supply pump 3 to the deepest part of the ground through the medium injection pipe 50, and pressurizes the hot water while the heat medium extraction pipe 80 to the ground by The transferred hot water L3 is decompressed and boiled by the pressure regulating valve PV1 and transferred to the steam separator F. Steam and hot water are separated by the steam separator F, and the generated steam V1 is supplied to the steam turbine T.

The geothermal power generation system 1 supplies generated steam V1 to a steam turbine T to rotate a generator G to generate electricity, supplies electricity to a power receiving facility TF, and supplies electricity to an electric power company or the like via a power transmission network. are supplying.
The steam turbine T may be of not only a turbine type but also a screw type or the like as long as it can generate electricity with steam. The steam V1 supplied to the steam turbine T boils the hot water L3 under reduced pressure and is separated by the steam separator F into hot water and steam.

Since the entire amount of hot water L3 supplied to the steam separator F is not converted into steam V1, a large amount of hot water L4, so-called drain, is sent from the steam separator F to the hot water service tank 4. The steam V3 exhausted from the steam turbine T is sent to the condensing unit 17, and the steam V4 sent to the condensing unit 17 is sent to the cooling tower 15 connected to the condenser 6. The sent steam V4 is condensed and returned to water, passes through the condenser 6, is temporarily stored in the condensate tank 14, and is sent to the hot water service tank 4 by the condensate pump 5. - 特許庁

The hot water L8 in the hot water service tank 4 is transferred to the heat medium transfer pipe 10 as the hot water L1 by the pressurized water supply pump 3 . The hot water L1 transferred by the pressurized water supply pump 3 absorbs heat from the underground heat again in the deep part where the geotropical zone U exists, and is heat-exchanged. The heat-exchanged hot water L2 is transferred by the pressurized water supply pump 3 through a heat medium transfer pipe 10, which will be described later.

(heat medium transfer pipe)
Next, the heat medium transfer pipe 10 will be described with reference to FIGS. 2 to 10. FIG. FIG. 2 is a perspective view showing part of the heat medium transfer pipe 10 of the present invention according to the first embodiment. FIG. 3 is a partially exploded perspective view of the medium injection tube 50 of the present invention according to the first embodiment. FIG. 4 is a longitudinal sectional view of part of the medium injection tube 50 of the present invention according to the first embodiment. FIG. 5 is a perspective view of the heat insulating tube 60 of the present invention according to the first embodiment. FIG. 6 is a longitudinal sectional view of part of the medium injection tube 50 of the present invention according to the first embodiment. FIG. 7 is a longitudinal section of part of the heat medium transfer pipe 50 of the present invention according to the first embodiment. FIG. 8 is a longitudinal sectional view of part of the heat medium take-out pipe 80 of the present invention according to the first embodiment. FIG. 9 is a schematic diagram of the water state change of the present invention according to the first embodiment. FIG. 10 is a relationship diagram showing the relationship between the depth of the heat medium transfer pipe 10 and the temperature distribution of hot water in the geothermal power generation system 1 of the present invention according to the first embodiment.

As shown in FIG. 10, a heat medium transfer pipe 10 is buried from the ground surface S to a geotropical zone U serving as a heat source located deep underground. The heat medium transfer pipe 10 has a cylindrical medium injection pipe 50 embedded on the outside, and the circumference of the medium injection pipe 50 extends from the ground surface S to the front of the geotropical zone U, that is, the temperature is lower than the temperature required for power generation. The temperature area is hardened with geothermal cement, etc., and is applied so that there is no danger of collapse. The heat medium transfer pipe 10 absorbs heat from the fluid or bedrock of the geotropical zone U located at the deepest part of the medium injection pipe 50 of the heat medium transfer pipe 10 . The length of the heat medium transfer pipe 10 varies depending on the temperature of the geotropical zone U, and extends to the geotropical zone U where the temperature of the flowing heat medium can be raised to around 200°C.

The medium injection pipe 50 is made of a material such as steel or stainless steel. In the region of the geotropical zone U where the temperature is high, the medium injection pipe 50 has a cylindrical fin with a circular cross section welded to it in order to increase the surface area of the outer periphery and facilitate the transmission of the heat of the geothermal zone U. The medium injection pipe 50 has a heat insulating structure, which will be described later, so that the hot water L1 pressurized and injected from the hot water service tank 4 does not lose heat in a low-temperature region near the ground surface S.

The heat medium transfer pipe 10 has a cylindrical heat medium take-out pipe 80 for transferring water heated in the geothermal heat U inside the medium injection pipe 50 . The heat medium take-out pipe 80 is formed in a cylindrical shape coaxially inside the medium injection pipe 50 . The heat medium take-out pipe 80 has a cylindrical inner side through which the hot water L3 can pass, and a vacuum insulating structure or a heat insulating material attached to the outer side along the vertical direction.

Further, the heat medium transfer pipe 10 will be described in detail with reference to FIGS. 2 to 11. FIG. The heat medium transfer pipe 10 is composed of a medium injection pipe 50 and a heat medium extraction pipe 80 .
First, the medium injection pipe 50 will be described with reference to FIGS. 2 to 7. FIG. FIG. 2 is a perspective view of the medium injection pipe 50 with the heat insulating material 70 removed. The medium injection pipe 50 is composed of the injection pipe 40, the pipe screw joint 51, the heat insulating pipe 60 shown in FIG. ing. The medium injection pipe 50 connects the injection pipe 40 with a pipe screw joint 51 to form a long tubular shape to the deepest portion U.

As shown in FIGS. 2 to 7, the injection tube 40 is covered with heat-resistant resin such as polyethylene, polypropylene, nylon 6, nylon 66, urethane foam, and fluorine on the outermost surface except for the grip part 47. A layer 46 is formed.
As shown in FIGS. 4 and 6, the injection tube 40 has a male screw portion 42 formed with a thread groove on the outer surfaces of both ends which are slightly tapered. 4, 6 and 7, the female threaded portion 52 and the male threaded portion 42 are hatched. The gripping portion 47 chucks the medium injection tube 50 and is provided in a state where the metal is exposed in order to hold the medium injection tube 50 itself when it is screwed in while managing the torque of the pipe threaded joint 51. 46 is not included. This is because the provision of the coating layer 46 may hinder the gripping force.

Next, the pipe threaded joint 51 shown in FIGS. 3, 4, 6 and 7 has a female threaded portion 52 having a thread groove formed therein so as to fit with the male threaded portion 42 . The pipe threaded joint 51 is a space in which the male threaded portion 42 is not formed in the center thereof, and is provided with a mounting space portion 53 as a space in which a projecting portion 62 (to be described later) is fitted.

Next, the heat insulating tube 60 shown in FIGS. 3 to 7 is made of a heat-resistant resin such as polyimide, polyimide amide, 66 nylon, peak, polyamide, or fluorine, and has a total length of about 1200 mm. An insertion tube 61 is provided. An annular projecting portion 62 having the same inner diameter as the outer diameter of the insertion tube 61 and formed of the same resin is joined to the center of the insertion tube 61 by ultrasonic welding or the like. Thereby, the insertion tube 61 and the projecting portion 62 are integrally formed. Note that the heat insulating pipe 60 may be integrally formed by molding instead of welding. The length of the heat insulating tube 60 in the vertical direction is formed so as to cover not only the grip portion 47 but also a part of the covering portion 46, and is designed in consideration of the influence of heat transfer received from the outside on the pipe threaded joint 51 and the injection pipe 40. ing.

Since the outer diameter of the projecting portion 62 is larger than the inner diameter of the injection pipe 40 , the heat insulating pipe 60 does not drop into the injection pipe 40 and the projecting portion 62 remains in the mounting space portion 53 . Moreover, since the outer diameter of the insertion tube 61 is smaller than the inner diameter of the injection tube 40 , the insertion tube 61 enters the inside of the injection tube 40 .
Due to the above structure, the medium injection pipe 50 is connected by screwing the pipe threaded joint 51, inserting the insertion pipe 61 of the heat insulating pipe 60 into the injection pipe 40, and inserting the other injection pipe 40 from above. The threaded joint 51 is screwed and connected.

Thus, the connection of the medium injection pipe 50 can be completed with a simple operation. Moreover, the heat insulating pipe 60 not only improves the heat insulating performance of the medium injection pipe 50, but also facilitates the replacement of the heat insulating pipe 60 itself and the installation of the medium injection pipe 50. FIG. Further, the projecting portion 62 is formed so as to be held between the injection pipes 40 even when pressure is applied to the hot water by the pressurized water supply pump 3 so that the hot water does not boil, and the hot water is pumped. . Therefore, the heat insulating tube 60 does not come off. Since both ends of the heat insulating pipe 60 are held between the injection pipes 40, the heat insulating pipe 60 does not come off in the vertical direction. Similarly, with respect to the heat medium take-out pipe 80, which will be described later, the heat insulating pipe 60 does not come off in the vertical direction.

Next, the heat insulating material 70 provided around the medium injection pipe 50 will be described with reference to FIG. The heat insulating material 70 is closely attached to the periphery of the medium injection pipe 50, and has a heat insulating layer 71 formed of a material such as glass wool and a protective film portion 72 formed of a metal film such as aluminum on the outermost periphery. The medium injection pipe 50 has a heat insulating structure with a heat insulating material 70 and a coating layer 46 on the outside of the pipe.

Next, the heat medium take-out pipe 80 will be described with reference to FIGS. 7 and 8. FIG. The heat medium extraction pipe 80 is provided to recover heat from deep underground with hot water, transport it to the ground, generate steam, and utilize the heat for steam power generation. 2 to 6, description of the portions of the heat medium take-out pipe 80 that are exactly the same as those of the medium injection pipe 50 will be omitted, and the different portions will be described. The heat medium extraction pipe 80 is located inside the medium injection pipe 50 and is composed of the extraction pipe 81 , the pipe screw joint 55 and the heat insulating pipe 90 .

The extraction pipe 81 corresponds to the structure of the injection pipe 40, the pipe threaded joint 55 corresponds to the structure of the pipe threaded joint 51, the mounting space portion 57 corresponds to the structure of the mounting space portion 53, and has a male screw. The portion 82 corresponds to the structure of the male threaded portion 42, the female threaded portion 56 corresponds to the structure of the female threaded portion 52, the heat insulating tube 90 corresponds to the structure of the heat insulating tube 60, and the coating layer 86 corresponds to the structure of the heat insulating tube 60. Corresponding to the structure of layer 46 , gripping portion 87 corresponds to the structure of gripping portion 47 and protrusion 92 corresponds to the structure of protrusion 62 . The heat medium take-out pipe 80 has a heat insulating portion 85 along the vertical direction, in which an air layer serving as a space or a heat insulating layer in which a heat insulating material is embedded is formed. The heat medium take-out pipe 80 has a heat insulating structure with the heat insulating pipe 60 to prevent heat transfer.

In this manner, the connection of the heat medium take-out pipe 80 is completed by a simple operation similar to the medium injection pipe 50 described above. Moreover, the heat insulating pipe 90 not only improves the heat insulating performance of the heat medium take-out pipe 80 but also facilitates the work of replacing the heat insulating pipe 90 itself and installing the heat medium take-out pipe 80 . In addition, the heat-retaining pipe 90, the heat-insulating portion 85, and the coating layer 86 improve the heat-retaining condition of the heat-retaining pipe 90, the heat-insulating portion 85, and the coating layer 86, in addition to the heat-retaining pipe 60 and the heat-insulating structure of the medium-injecting pipe 50. , the hot water L3 can be extracted from the ground without being deprived of heat.

Next, the data will be explained by an experiment showing the heat retention performance of the present invention. FIG. 11A is a schematic diagram of a conventional medium injection pipe 101. FIG. FIG. 11B is a schematic diagram of the medium injection tube 50 of the present invention. FIG. 11B shows experimental data showing the heat retention performance of the conventional medium injection tube 101 and the medium injection tube 50 of the present invention.
As shown in FIG. 11, the applicant measured the temperature at each point (P1 to P8) as shown in the schematic diagram in order to compare the thermal insulation performance of the medium injection pipe 50 of the present invention and the conventional medium injection pipe 101, A temperature gradient was determined. A heater is inserted into both pipes (101, 50), and the water heated by the heater and the outside of the pipes are filled with room temperature water. Compared to the medium injection tube 101 , the medium injection tube 50 additionally comprises a heat insulating tube 60 and a coating layer 46 .

As shown in FIG. 11(C), the measured temperature gradient was 890° C./m between P1 and P2 of the conventional medium injection pipe 101, and 3980° C./m between P5 and P6 of the medium injection pipe 50 of the present invention. °C/m, indicating that the medium injection pipe 50 of the present invention has a larger temperature difference than the conventional medium injection pipe 101, and it can be confirmed that the heat insulating pipe 60 improves the heat insulation performance.
Further, the distance between P3 and P4 of the conventional medium injection pipe 101 is 3420° C./m, and the distance between P7 and P8 of the medium injection pipe 50 of the present invention is 9790° C./m. , indicates that the temperature difference is larger than that of the conventional medium injection pipe 101, and it can be confirmed that the coating layer 46 improves the heat insulation performance.
As described above, the present invention can provide the heat medium transfer pipe 10 with improved heat insulating performance.

The hot water L3 heated in the geotropical zone U is decompressed and boiled by the pressure regulating valve PV1 to generate steam. Here, the steam separator F is connected to the pressure regulating valve PV1, and the nozzle for generating steam may be a nozzle capable of generating microbubbles or nanobubbles that become microbubbles by self-priming. good. With this configuration, the efficiency of steam generation can be improved, and a sufficient amount of steam can be secured even if the speed of water transfer is reduced, so that the residence time of water in the heat absorption region of the geotropical zone U can be increased. This allows the water to take time to absorb the heat, making it a high-temperature hot water.

As another modified example with improved heat insulation performance, another embodiment of the heat medium take-out pipe 80 will be described with reference to FIG. FIG. 23 is a longitudinal sectional view showing a modification of the heat medium take-out pipe 80a according to the first embodiment. The same reference numerals are assigned to the same parts as in the above-described embodiment, and the above description is omitted.
The heat medium extraction pipe 80a is provided for recovering heat from deep underground with hot water, transporting it to the ground, generating steam at the pressure control valve PV1 (FIG. 1), and utilizing the heat for steam power generation. . The heat medium take-out pipe 80 a is positioned inside the medium injection pipe 50 and is composed of a take-out pipe 81 a , a pipe screw joint 55 and a heat insulating pipe 91 .

The extraction pipe 81a has thread grooves on the outer periphery of both ends. Further, the threaded pipe joint 55 is provided with a thread groove on its inner periphery so as to fit with the thread groove of the take-out pipe 81a. The take-out pipe 81 a can be extended by fitting and connecting the take-out pipes 81 with a pipe screw joint 55 .

Further, as shown in FIG. 23, a heat insulating pipe 91 made of resin such as polyimide, polyimide amide, 66 nylon, PEEK, polyamide or fluorine is divided near the center of the pipe joint 55 and the take-out pipe 81a. It covers the entire length of the extraction pipe 81a. In this manner, not only part of the heat medium take-out pipe 80a but also the entire length of the take-out pipe 81a is covered with the heat insulating pipe 91, so that the take-out pipe 81a does not need to be provided with a heat insulating structure such as an air layer or a heat insulating material. Therefore, it is possible to transport the heat medium to the ground at a low cost while keeping the heat retention of the heat medium good.

The heat-insulating pipe 91 has ring-shaped protrusions 92a and 92b formed of the same resin and having the same inner diameter as the outer diameter of the heat-insulating pipes 91a and 91b. ing. As a result, the heat insulating tubes 91a, 91b and the projecting portions 92a, 92b are integrally formed. Note that the heat insulating pipe 91 may be integrally formed by molding instead of welding.

Since the outer diameter of the projecting portions 92a and 92b is larger than the inner diameter of the extraction pipe 81a, the heat insulating pipe 91 does not drop into the extraction pipe 81a and the projecting portions 92a and 92b remain in the mounting space portion 53. In addition, since the outer diameter of the portion where the heat insulating tube 91 is inserted is smaller than the inner diameter of the extraction tube 81a, the heat insulating tube 91 enters the inside of the extraction tube 81a.
With the structure described above, the extraction pipe 81a is connected by screwing the pipe threaded joint 55, inserting the heat insulating pipe 91 into the extraction pipe 81a, and screwing the other extraction pipe 81a to the pipe threaded joint 55 from above. and concatenate.

Thus, the work of connecting the heat medium take-out pipes 80a is completed by a simple work. Moreover, the pressurized water supply pump 3 applies pressure to the protrusions 92a and 92b so that the hot water does not boil. is formed as follows. Therefore, the heat insulating pipe 91 does not come off.
As described above, since both ends of the heat insulating pipe 91 are held between the extraction pipes 81a, the heat insulating pipe 91 does not come off in the vertical direction.

As shown in FIG. 23, the pipe threaded joint 55 is made of a tube-shaped resin such as polyolefin resin or polypropylene resin that can shrink when heat is applied after the take-out pipe 81a is connected by the pipe threaded joint 51. Alternatively, a heat insulating structure for preventing heat transfer is provided by providing a pipe threaded joint covering portion 93 covered with a tape of polyolefin resin, polypropylene resin, or the like. With the above structure, the heat medium take-out pipe 80a has the pipe threaded joint cover portion 93 that blocks the heat transfer at the portion of the pipe threaded joint 55 .

In this embodiment, water is used as a medium for heat exchange in the geotropical zone U. As a medium, oil, gas (inert gas (nitrogen, carbon dioxide, etc.)) or water used in binary power generation has a boiling point of A medium with a low λ (such as a mixture of water and ammonia) is contemplated. In addition, when water or an inert gas is used as a medium, even if the heat medium transfer pipe 10 is damaged and leaks to the outside, the water or inert gas will not harm the environment and the work can be performed. It is possible to handle safely even in terms of surface.

(steam separator)
The steam separator F shown in FIG. 1 is a cylindrical pressure vessel, and a nozzle provided in the steam separator F ejects hot water L3 from the tip, and steam V1 and steam V1 and Hot water L4 is separated. A pressure regulating valve PV1 is provided inside or outside the steam separator F to adjust the pressure (the amount of steam generated). Further, a pressure regulating valve PV2 is provided in a passage leading to the hot water service tank 4 that collects the drain L4, and regulates the steam pressure from the steam separator F to the turbine T, It can also be used to control the amount of steam going to the

(hot water service tank)
Next, the hot water service tank 4 will be described with reference to FIG. The hot water service tank 4 is a cylindrical pressure vessel. The main pipes connected to the hot water service tank 4 are a pipe for taking in condensate L6 sent from the condensate unit 17, a pipe for taking in degassed water L7 replenished from the water supply unit, and a pressurized water supply pump 3. A pump pipe for sending hot water L8 from the hot water service tank 4, a drain injection pipe for taking in drain L4 sent from the steam separator F, and a steam discharge pipe for discharging steam V2 generated by boiling of the pool in the hot water service tank 4. is provided.

(water supply unit)
A water supply unit 18 generates soft water from raw water 16 such as river water or tap water using an industrial soft water generator 9 . The produced soft water is stored in the make-up water tank 8 . A deoxidizer or a deoxidizer is used to remove dissolved oxygen from the stored soft water.

The degassed water L7 from which oxygen has been removed passes through the hot spring service tank 4 during the initial operation of the geothermal power generation system 1, after washing the heat medium transfer pipe 10, and when replacing with water for operation. sent. By removing the oxygen, it is possible to prevent rust and scale formation in the heat medium transfer pipe 10 . In particular, since the heat medium transfer pipe 10 has a long overall length, if the generation of scale on the inner wall is suppressed over the entire stroke of the transfer pipe, pressure loss can be reduced, leading to energy saving of electric power in the station.

Representative examples of deacidifiers include hydrazine, tannin, products derived directly from plants, and the like. There are also deoxidizers that use inert gases, and inert gases that are less likely to cause chemical reactions are used. Nitrogen, argon, etc., which are less harmful, are used as examples of inert gases. In particular, as in the present invention, it is necessary to control the pressure of the heat-exchanging medium at high temperatures, so deoxidizing agents and deoxidizing devices that do not cause changes in the physical properties of the working fluid are preferred.
Nitrogen or the like is easily dissolved in water using a microbubble generator, and then the dissolved water is injected to facilitate replacement with oxygen.

During normal operation, the degassed water L7 in the water supply unit 18 is low in temperature, so the water supply unit 18 supplies insufficient water via the condensate unit 18 without directly entering the hot water service tank 4 having a high temperature. Also, in cooling the condensing unit 18, it is possible to use the raw water 16 for cooling.

(condensing unit)
Next, the condensing unit 17 will be explained. The condensing unit 17 has a function of condensing the steam V3 discharged from the turbine T and returning it to water, and is mainly composed of the condenser 6, the condensing tank 14 and the cooling tower CT. The steam V3 received by the condenser 6 is cooled by the cooling tower CT, condensed, returns to the hot water L10, passes through the condenser 6, and is stored in the condensate tank 14. The stored hot water L6 is sent to the hot water service tank 4 by the condensate pump 5 and stored in the hot water service tank 4 .
Cooling methods using the cooling tower CT include an air-cooling method, a water-cooling method using river water or seawater, and a geothermal heat exchange method in which heat is exchanged underground.

(Power generation method for generating power using the above system)
The power generation method will be explained with reference to FIGS. 1, 9 and 10. The depth of the hole drilled by boring to obtain steam with a temperature of around 200° C. has reached a depth of It is considered that the deeper the depth, the higher temperature can be obtained, but it is determined in consideration of excavation costs. The following values also change appropriately depending on the temperature obtained from the vicinity of the part.

First, the power generation method of the geothermal power generation system 1 will be described. A heat medium transfer pipe 10 is buried in the ground. It reaches deep into the earth. In addition, the medium injection pipe 50 reaches the bottom of the medium injection pipe 50 with the heat medium extraction pipe 80 connected to the inside of the medium injection pipe 50 . These heat medium transfer pipes 10 are used as a heat exchange section that absorbs heat obtained from the geothermal heat U. This pressurized water power generator A evaporates hot water to generate power through a steam turbine T. The power generation method by the pressurized water power generator A will be described in detail below.

For example, hot water (L1) in the hot water service tank 4 is pressurized to 5 MPa by the pressurized water supply pump 3 and sent to the medium injection pipe 50 of the heat medium transfer pipe 10 at a flow rate of 55 t / h. transferred to. The hot water transferred to the geothermal heat U at 210° C. absorbs heat from the geothermal heat U through the medium injection pipe 50 having a high effective thermal conductivity, and finally becomes hot water (L2) at 200° C. The hot water (L3) taken out from the heat medium take-out pipe 80 is transferred to the steam separator F with a temperature of 200° C. and a pressure of 2.0 MPa at the outlet.

In the steam separator F, the hot water (L3) at a temperature of 200°C is depressurized by the pressure control valve PV1, boiled under reduced pressure to about 0.6 MPa, and the amount of steam generated at a flash rate of about 11% is 6 t/ h vapors are separated. The steam separator F sends the generated steam (V1) to the steam turbine T.
The generated steam (V1) joins the steam (V2) generated in the hot water service tank 4 in the steam separator F. The merged steam (V1+V2) drives the generator G with the rotation of the steam turbine T to generate electricity. The amount of power generated by this steam (V1+V2) is about 112 kWh when the efficiency is 80%.

In addition, the steam separator F connected to the hot water service tank 4 by piping removes about 89% of the remaining hot water (L4) that has not turned into steam, while maintaining a temperature of around 160°C and a pressure of 0.00°C. It is sent to the hot water service tank 4 at a flow rate of 49 t/h at 6 MPa.

Also, steam (V3) exhausted from the steam turbine T is sent to the condenser 6 . The steam (V4) sent to the condenser 6 is sent to an air-cooled or water-cooled cooling tower CT, condensed by the cooling tower CT and returned to hot water (L10) of 100° C. and a pressure of 0.101 MPa. The returned hot water (L10) is stored in the condensate tank 14 at a flow rate of 6 t/h. Hot water (L6) in the condensate tank 14 is sent to the hot water service tank 4 by the condensate pump 5 .
Then, the hot water (L1) of about 130° C. in the hot water service tank 4 is again pressurized to 6 MPa by the pressurized water supply pump 3 and sent to the medium injection pipe 50 of the heat medium transfer pipe 10 at a flow rate of 55 t/h. It is transported to the deep geotropic U.

FIG. 10 is a diagram showing the relationship between the depth of the heat medium transfer pipe 10 of the pressurized water power generator 1 and the temperature distribution of the hot water. A dashed line indicates the underground temperature distribution 21 , and a solid line indicates the temperature distributions of the hot water L1, L2, L3 in the medium injection pipe 50 and the heat medium extraction pipe 80 .
Bounded by the alternate long and short dash line, the upper heat insulating region 22 uses a pipe with an excellent heat insulating effect that employs a material having an effective thermal conductivity of 0.1 W/m·K or less for the medium injection pipe 50 . In the absorption region 26 below the dashed line, the medium injection pipe 50 is made of a material having an effective thermal conductivity of 50 W/m·K or more and has excellent heat absorption.

In addition, the heat medium take-out pipe 80 is made of a material having an effective thermal conductivity of 0.1 W/m·K or less regardless of the heat insulation area 22 and the heat absorption area 26, and has an excellent heat insulation effect. Due to the heat insulating effect, the hot water (L2) that has absorbed the heat of the deepest geotropical zone U can be transferred to the pressure regulating valve PV1 without being affected by temperature changes in the middle of the medium injection pipe 50 .

FIG. 9 is a schematic diagram of the state change of water. FIG. 9 shows the temperature and pressure when water changes from solid to liquid to gas. A solid line from the triple point to the critical point indicates the evaporation curve 27 . The boiling point at atmospheric pressure is 100°C, indicating 0.101 MPa. At point C on the line, at a temperature of 200° C., if the pressure is less than 1.554 MPa, it is the boundary line where the state of water changes to gas, ie steam.

At point D on the line, when the temperature is 210° C. and the pressure is less than 1.907 MPa, the state of water becomes a boundary line that changes to gas, that is, steam.
A pressurization region 23 indicated by diagonal lines indicates a pressure region in which the hot water L3 does not become steam, and the pressurization water supply pump 3 sets the pressure value in consideration of the pressure loss.

In the temperature distribution 21, the temperature rises and reaches 220° C. as the depth of the geotropical zone U approaches. The effective thermal conductivity of the medium injection pipe 50 and the heat medium extraction pipe 80 is 50 W/m·K. The temperature distribution 22 rises along .

Here, even if the effective thermal conductivity of the heat medium take-out pipe 80 is set as low as 0.1 W/m·K, when the pressure of the hot water L3 at the outlet of the heat medium take-out pipe 80 is lower than point C, Since the temperature distribution is lower than the evaporation curve 27, steam is generated and the temperature is lowered so as to approach the boiling point.

When water changes to steam in the heat medium take-out pipe 80, it becomes a so-called gas-liquid two-phase flow. Alternatively, heat is likely to be lost by the low-temperature descending flow L1 flowing through the medium injection pipe 50 . In order to prevent the heat loss and transport the hot water with the energy stored, it is necessary to make it difficult to cool the hot water.
The hot water having a boiling point or higher heated in the geotropical zone U is conveyed to the steam separator F without cooling, thereby reducing heat loss. In order to reduce the heat loss, it is necessary to keep the pressure higher than the evaporation curve 27 in FIG. 13 as described above.

In particular, a temperature difference occurs in the heat medium transfer pipe 10, which serves as a heat exchanger, and buoyancy is generated due to the density difference of water. The pressurized water supply pump 3 does not have enough pressure to transfer the necessary flow rate only by natural circulation of buoyancy, and the pressure loss of the medium injection pipe 50 and the heat medium extraction pipe 80 must be considered.

In addition, the pressurized water supply pump 3 maintains a high pressure in order to maintain a pressure higher than the evaporation curve 27, thereby maintaining a state in which the heat medium in the heat medium transfer pipe 10 is not boiled. is important. An advantage of the present invention is that underground heat can be effectively used by transferring the hot water L3 that retains the amount of heat absorbed in the geotropical zone U, that is, in a so-called single-phase flow state, to the pressure control valve PV1.

In view of the above, in the present invention, the heat insulating regions of the medium injection pipe 50 and the heat medium extraction pipe 80 are formed of a material having an effective thermal conductivity of 0.1 W/m·K or less, as shown by the hatching in FIG. bottom. The best ones are those having a heat insulation performance of 0.05 W/m·K to 0.001 W/m·K. By maintaining the heat insulation performance, the temperature drop at the outlet is prevented, and as a result, there is an advantage that the pressure of the pressurized water supply pump 3 does not need to be set high. In FIG. 14, the dashed line indicates the underground temperature distribution 21 including the geotropical zone U, and the solid line indicates the temperature distribution 25 of the hot water.

Considering the pressure loss in the medium injection pipe 50 and the heat medium extraction pipe 80, the outlet pressure of the hot water L3 is desirably in a pressure range 23 that is at least higher than the evaporation curve 27 in FIG. The pressure was set so as not to generate steam so that the hot water whose temperature is above the boiling point can be transferred as it is.

Furthermore, the medium injection pipe 50 was made of a material with a high effective thermal conductivity of 50 W/m·K in the area of high underground temperature distribution, that is, the heat absorption area required for power generation. The higher the effective thermal conductivity, the better. However, considering the pressure and corrosion in the ground, it is desirable to use a metal material, and the effective thermal conductivity should be 20 W/m K or more. Just do it.

(Second embodiment)
A geothermal power generation system 200 according to the second embodiment will be described with reference to FIG. FIG. 12 is a schematic diagram showing the configuration of the geothermal power generation system 200 of the present invention according to the second embodiment. The same reference numerals are given to the same parts as in the first embodiment, and the above description is omitted.
The binary power generator B will be described with reference to FIG. 12. The binary power generator B mainly includes a heat exchange section 150 connected to the pressurized water power generator 1b, a steam turbine T2, a generator G2, a power receiving facility TF2, It is composed of a cooler 154 and a circulation pump 155 .

In the present invention, the hot water L3 obtained from the heat medium transfer pipe 10 provided in the pressurized water power generator 1b is separated into steam by the steam separator F, and the drain L4 that has not become steam is temporarily stored in the storage tank 11. store. Also, the steam V3 obtained from the turbine T is returned to hot water by the condenser 6 and stored in the storage tank 11 . The hot water L4 stored in the reservoir 11 is supplied to the heat exchanger 151 of the binary power generator B. As shown in FIG.

The working medium M1 heated in the heat exchange section 150 evaporates to rotate the steam turbine T2, and the rotation causes the generator G2 to generate electricity.
The power receiving facility TF supplies electricity to a power company or the like via a power transmission network. Here, the working medium M may be HFC-245fa, R245fa, etc., which are non-flammable or non-toxic inert gases, or a medium with a low boiling point (a mixture of water and ammonia, etc., hydrocarbon (pentane)), or the like.

An expansion turbine or the like is used as the steam turbine T2. The working medium M2 that has passed through the steam turbine T2 is cooled by cooling water 157a, 158b of the cooler 156. Also, the working medium M3 is condensed from gas to liquid or the like and sent to the heat exchanger 152 again by the circulation pump 155 .

The cooling water 157b, 158b is piped to the raw water 16 provided in the water supply unit 18 of the pressurized water power generator 1b, and heat is exchanged. There is an effective displacement of heat in the system. The raw water 16 can be directly injected into the hot water service tank 4 without going through the condensing unit 17 by being heated.

By using such working mediums (M1 to M3), even with hot water of 70° C. to 95° C., power generation is possible if there is a flow rate of 9 t/h to 24 t/h. In this system, heat exchange is performed in a system in which the medium is closed.

Since the working medium (M1 to M3) that can be used is determined by the temperature at which heat is exchanged, the binary power generator B may impose a temperature limit. The pressurized water power generator 1b is provided with a temperature control system 161 using the air cooling tower CT of the condensate unit 17 so as to be able to cope with such a case. In particular, when the temperature of the drain L4 that has not turned into steam is high, it is possible to lower the temperature to a range that matches the set temperature of the binary power generator B.

The hot water L3 sent from the heat medium transfer pipe 10 may be directly supplied by the heat exchanger 151, and the binary power generation device B may be configured to generate power. It is possible to efficiently use geothermal heat to generate power when the temperature is low.

(Third embodiment)
A geothermal power generation system 300 according to the third embodiment will be described with reference to FIG. FIG. 13 is a schematic diagram showing the configuration of a geothermal power generation system 300 of the present invention according to the third embodiment. The same reference numerals are given to the same parts as those in the first embodiment and the second embodiment, and the above description is omitted.
The binary power generator C will be described with reference to FIG. 13. The binary power generator C includes a first heat exchange section 150c, a second heat exchange section 156c connected to the pressurized water power generator 1b, a steam turbine T2, and a steam turbine T3. , a generator G2, a generator G3, a power receiving facility TF2, a cooler 164c, a first circulation pump 155c, and a second circulation pump 165c.

In the present invention, the hot water L3 obtained from the heat medium transfer pipe 10 provided in the pressurized water power generator 1c is separated into steam by the steam separator F, and the drain L4 that does not become steam is transferred to the first heat exchanger 151c. pass through.
The working medium M1 heated in the first heat exchange section 150c evaporates to rotate the steam turbine T2, thereby generating power by the generator G2.

The power receiving facility TF2 supplies electricity to a power company or the like via a power transmission network. Here, the working medium M (M1 to M23) is a non-flammable or non-toxic inert gas HFC-245fa, R245fa, etc., or a medium with a low boiling point (a mixture of water and ammonia, etc., hydrocarbon (pentane)), etc. be done. Further, in this embodiment, the working medium (M1 to M3) used in the binary power generator C is a working medium having a high boiling point range and a working medium (M21 to M3) having a boiling point lower than that of the working medium (M1 to M3). By using a working medium having two types of boiling point regions of M23), heat can be utilized in multiple stages, and electric power can be efficiently generated.

Expansion turbines or the like are used as the steam turbines T2 and T3. The working medium M2 that has passed through the steam turbine T2 is heat-exchanged and cooled by the second heat exchanger 153c of the second heat exchange section 154c. Also, the working medium M3 is condensed from gas to liquid or the like and sent to the heat exchanger 152c again by the circulation pump 155c.
Further, heat exchange is performed by the second heat exchanger 153c of the second heat exchange section 154c, and the working medium M21 heated by the second heat exchange section 164c evaporates to rotate the steam turbine T3, thereby generating a power generator. Power is generated by G3.

The working medium M21 that has passed through the steam turbine T3 is cooled by cooling water 157c, 158c of the cooler 164c. Also, the working medium M23 is condensed from gas to liquid or the like, and sent again to the second heat exchange section 154c by the circulation pump 165c.
The cooling water 157c, 158c is piped to the raw water 16 provided in the water supply unit 18 of the pressurized water power generator 1c, and heat is exchanged, so that the raw water 16 is warmed and the cooling water 157c, 158c is cooled. An efficient displacement of heat takes place at . The raw water 16 can be directly injected into the hot water service tank 4 without going through the condensing unit 17 by being heated.

The method of cooling the working medium or water connected to the heat exchanger or condenser described above is not limited to these, and a method of cooling by a heat exchange method using a Peltier element, etc. Various methods are conceivable.

(Fourth embodiment)
A geothermal power generation system 100 according to the fourth embodiment will be described with reference to FIG. FIG. 14 is a schematic diagram showing the configuration of the geothermal power generation system 100 of the present invention according to the fourth embodiment. The same reference numerals are assigned to the same parts as in the first to third embodiments, and the above description is omitted.
The binary power generation device B will be described with reference to FIG. 14. The binary power generation device B mainly includes a heat exchange section 150 connected to the pressurized water heat exchange device 1a, a steam turbine T2, a power generator G2, and a power receiving facility TF2. , a cooler 154 and a circulation pump 155 .

In the geothermal power generation system 100, the hot water L3 pressurized from the medium transfer pipe 10 provided in the pressurized water heat exchanger 1a is passed through the heat exchanger 151 as hot water without being steamed. Since the geothermal power generation system 100 is not provided with the steam separator F as described above, the geothermal heat is absorbed by the hot water and directly used to reduce the loss and recover the geothermal heat for power generation. can

The working medium M1 heated in the heat exchange section 150 evaporates to rotate the steam turbine T2, thereby generating power by the generator G2.
The power receiving facility TF supplies electricity to an electric power company or the like via a power transmission network. Here, the working mediums M1, M2, and M3 are HFC-245fa, R245fa, etc., which are non-flammable and non-toxic inert inert gases, mediums with low boiling points (mixtures of water and ammonia, etc., hydrocarbons (pentane)), etc. used.

An expansion turbine or the like is used as the steam turbine T2. The working medium M2 that has passed through the steam turbine T2 is cooled by cooling water 157a, 158a of the cooler 156. Also, the working medium M3 is condensed from gas to a liquid or the like and sent to the heat exchanger 152 again by the circulation pump 155 .

By using such working media (M1 to M3), the geothermal power generation system 100 can generate power with a flow rate of 9t/h to 24t/h even with hot water of 70°C to 95°C. be. In this system, the working medium exchanges heat in a closed system.

In addition, the service tank 4 provided in the pressurized water heat exchanger 1a stores the hot water cooled by the heat exchanger 152. As an element for keeping the pressure of the entire system of the pressurized water heat exchanger 1a constant, It is necessary along with the pressurized water supply pump 3. In particular, when the pressurized water supply pump 3 is stopped due to maintenance or the like, the pressurized water heat exchange device 1a increases or decreases the water capacity of about 2 tons out of the total system capacity. To resume operation, the pressure in the service tank 4 can be controlled to keep the water level constant.

(Fifth embodiment)
The heat medium transfer pipe 500 according to the fifth embodiment and the construction method of the heat medium transfer pipe 500 will be described with reference to FIGS. 15 to 20. FIG. FIG. 15 is a vertical cross-sectional view with a part omitted of the heat medium transfer pipe 500 of the present invention according to the fifth embodiment. FIG. 16 is a vertical cross-sectional view of the heat medium transfer pipe 500 of the present invention according to the fifth embodiment during construction. FIG. 17 is a vertical cross-sectional view of the heat medium transfer pipe 500 of the present invention according to the fifth embodiment during construction. FIG. 18 is an enlarged schematic view of the pipe screw joint 51 of the heat medium transfer pipe 500 of the present invention according to the fifth embodiment. FIG. 19 is a vertical cross-sectional view with a part omitted of the heat medium transfer pipe 500 of the modified example of the present invention according to the fifth embodiment. FIG. 20 is a relational diagram showing the relationship between the depth of the heat medium transfer pipe 500 and the temperature distribution of hot water in the geothermal power generation system of the present invention according to the fifth embodiment. The same reference numerals are assigned to the same parts as in the first to fourth embodiments, and the above description is omitted.

The heat medium transfer pipe 500 shown in FIG. 15 shows an example in which the heat medium transfer pipe 500 is provided extending from the ground surface S to a depth of 3000 m at the deepest part. The heat medium transfer pipe 500 has the heat medium take-out pipe 80 in the center and the medium injection pipe 50, the first protection pipe 31, the second protection pipe 32 and the third protection pipe 33 on the outer circumference. ing. The first to third protective pipes 31 to 31 are annular pipes extending toward the geotropical zone U. As shown in FIG.

As shown in FIG. 20, a heat medium transfer pipe 500 is applied to the pressurized water power generators 1, 1a, 1b, and 1c (FIGS. 1 and 12 to 14) used in the first to fourth embodiments. 5 is a relational diagram between the depth of the pipe 500 and the temperature distribution of hot water. FIG. A dashed line indicates the underground temperature distribution 21 , and a solid line indicates the temperature distributions of the hot water L1, L2, L3 in the medium injection pipe 50 and the heat medium extraction pipe 80 .

Bounded by the alternate long and short dash line, the upper heat insulating region 22 uses a pipe with an excellent heat insulating effect that employs a material having an effective thermal conductivity of 0.1 W/m·K or less for the medium injection pipe 50 . In the absorption region 26 below the dashed line, the medium injection pipe 50 is made of a material having an effective thermal conductivity of 50 W/m·K or more and has excellent heat absorption.

In addition, the heat medium take-out pipe 80 is made of a material having an effective thermal conductivity of 0.1 W/m·K or less regardless of the heat insulation area 22 and the heat absorption area 26, and has an excellent heat insulation effect. Due to the heat insulation effect, the hot water (L2) that has absorbed the heat of the deepest geotropical zone U can be transferred, for example, to the pressure control valve PV1 in FIG. 1 without being affected by temperature changes in the middle of the medium injection pipe 50. .

The first to third protection tubes 31 to 33 are located in the heat insulating region 22 and each have a heat insulating structure. While hardening the side walls with geothermal cement or the like, the excavator digs deep into the ground.
As shown in FIGS. 15 and 18, the first protective tube 31 shields convection from the disk-shaped hot water 74 below the tube screw joint 51 connecting the injection tubes 40 of the medium injection tube 50 to above. Both of them are provided with a convection shielding plate 73 (convection shielding means) for preventing outbursts during construction. The convection shielding plate 73 has an inner diameter smaller than the outer diameter of the pipe threaded joint 51, and has a structure that prevents it from coming off upward due to the hydraulic pressure of ground water or the like.

The convection shielding plate 73 prevents hot water that has entered the gap between the medium injection pipe 50 and the first protection pipe 31 from below from mixing with the low-temperature groundwater above due to convection and turning into low-temperature water. , the heat retention performance of the medium injection pipe 50 is further enhanced. Therefore, the heat medium transfer pipe 500 receives the convection shielding plate 73 at a plurality of locations in the vertical direction, thereby further enhancing the heat retention performance. The convection shielding board 73 is not limited to a material such as metal, resin, or rubber, and may have a structure in which cloth or the like is spread around the medium injection pipe 50 .

Next, the heat medium transfer pipe 500 is provided with a heat insulating structure constructed by a construction method described later between the first protective pipe 31 and the second protective pipe 32 and between the second protective pipe 32 and the third protective pipe 33. ing. The heat medium transfer pipe 500 uses a lightweight aggregate such as polystyrene foam or a large amount of air bubbles between the first protective pipe 31 and the second protective pipe 32 and between the second protective pipe 32 and the third protective pipe 33 . Mixed or generated concrete, so-called foamed concrete 36, 37 is used to provide a heat insulating structure with cushioning, heat insulating and non-water absorbing properties.
Between the first protective pipe 31 and the second protective pipe 32 and between the second protective pipe 32 and the third protective pipe 33, there are provided closed portions 34 and 35 which are closed with concrete material.

The closed portions 34 and 35 prevent water having a temperature lower than that of the medium injection pipe 50 from entering from below, and improve the heat insulating performance of the heat medium transfer pipe 500 . The upper portion of the heat medium transfer pipe 500 is also closed with concrete or steel (not shown) to prevent water from entering from above.

Next, a construction method of the heat medium transfer pipe 500 of the present invention will be described with reference to FIGS. 15 to 17. FIG.
First, excavate to the point of 700 m with the largest diameter using excavating machinery. During excavation, the side walls are solidified with geothermal cement, etc., to prevent collapse. 35 is formed and the above-mentioned third protective tube 33 is embedded.

Next, as shown in FIGS. 15 and 17, the diameter of the excavator is reduced, and excavation is performed to a size that allows the second protective pipe 32 to be buried, and the excavation is advanced to the point of 1500 m. When the 700 m point is reached, as shown in FIG. 17, a block portion 34 is formed with a concrete material in a section from 10 m to 100 m deep, and the above-described second protective pipe 32 is buried. .
Next, as shown in FIG. 15, the diameter of the excavator is further reduced, and excavation is performed to a size that allows the first protective pipe 31 to be buried, and the adiabatic area 22 is excavated to a position of about 1700 m, and the above-mentioned first pipe is excavated. 1 The protective tube 31 is buried.

Finally, as shown in FIG. 15, the diameter of the excavator is further reduced, and excavation is performed to a size that allows the medium injection pipe 50 to be buried. It is dug up to a position of about 3000 m, and the medium injection pipe 50 and the heat medium extraction pipe 80 are buried.

Here, the endothermic region 26 does not always have enough hot water, and the bedrock zone 38 or the fracture zone 43 may also be considered. After the excavation reaches the deepest part U, as shown in FIG. Water is filled between the bedrock zone 38 and the medium injection pipe 50 as the transfer enhancing medium 39 . Water may be injected later, but a method of leaving the water used during hydraulic fracturing or mud excavation as it is may be used.

As shown in FIG. 19, when the heat absorption region 26 is the crushing zone 43, the heat medium transfer pipe 500 has gaps between the crushing zones and there is no hot water. A metal cup-shaped receiving pipe 75 for receiving water as the transmission promoting medium 39 may be inserted between the pipes 43 . Water is filled between the receiving pipe 75 and the medium injection pipe 50 as a transfer promoting medium 39 in order to improve the heat conduction between the medium injection pipe 50 and the geothermal heat U. The transfer promoting medium 39 may be not only water but also a liquid resin or the like containing a metal that facilitates heat transfer as a medium.

As described above, the present invention provides an intermediate substance between the heat medium transfer pipe 500 and the geotropical zone U even if the geotropical zone U in the heat absorption region 26 is the bedrock zone 38 or the fracture zone 43 with poor heat transfer. It is possible to intervene and absorb the heat of the geotropical zone U efficiently.

A receiving tube 75 shown in FIG. 24 is a schematic diagram showing a lower part of the receiving tube 75 shown in FIG. The receiving tube 75 is provided with a medium moving hole 76 which is a through hole penetrating through the side surface. The receiving pipe 75 is provided with a hole so that the medium such as hot water can move through the medium moving hole 76 when the geothermal field U is covered with a fluid medium such as hot water.

The receiving pipe 75 protects the medium injection pipe 50 from being crushed by the bedrock or the like due to collapse of the bedrock or the like, and prevents rocks or the like from entering the region where the side wall of the medium injection pipe 50 contacts the medium such as hot water. I'm trying
Incidentally, the medium moving hole 76 may be a hole made of metal or the like and formed in a mesh shape. In this way, the receiving pipe 75 preferably has a structure that prevents rocks, sand, etc. from coming into contact with the medium injection pipe 50 when the geothermal heat U is hot water. It is possible to secure a contact area.

(Sixth embodiment)
A configuration of a geothermal power generation system 400 of the present invention according to a sixth embodiment will be described with reference to FIGS. 21 and 22. FIG. FIG. 21 is a schematic diagram showing the configuration of a geothermal power generation system 400 of the present invention according to the sixth embodiment. FIG. 22 is a schematic diagram showing the configuration of a heat medium transfer pipe 410f of the present invention according to the sixth embodiment.

As shown in FIG. 21, the geothermal power generation system 400 mainly includes a pressurized water supply pump 3, a plurality of heat medium transfer pipes 410 (a to f), a hot water service tank 4, a condensate unit 17, a water supply unit 18, and a steam separator. It consists of a vessel F, a steam turbine T, a generator G and a power receiving facility TF.
The geothermal power generation system 400 heat-exchanges water as a medium supplied from the pressurized water supply pump 3 through the medium injection pipe 50 at the deepest part of the earth, and pressurizes the water that has become hot water while discharging the heat medium extraction pipe. 80 to the ground. The transferred hot water L3 is decompressed and boiled by the pressure regulating valve PV1 and transferred to the steam separator F.

Steam and hot water are separated by the steam separator F, and the generated steam V1 is supplied to the steam turbine T. The geothermal power generation system 400 supplies the generated steam V1 to the steam turbine T to rotate the generator G to generate electricity, supplies electricity to the power receiving equipment TF, and supplies electricity to the electric power company or the like via the power transmission network. are supplying.
The steam turbine T may be of not only a turbine type but also a screw type or the like as long as it can generate electricity with steam.

Since the entire amount of hot water L3 supplied to the steam separator F is not converted into steam V1, a large amount of hot water L4, so-called drain, is sent from the steam separator F to the hot water service tank 4. The steam V3 exhausted from the steam turbine T is sent to the condensing unit 17, and the steam V4 sent to the condensing unit 17 is sent to the cooling tower 15 connected to the condenser 6. The sent steam V4 is condensed and returned to water, passes through the condenser 6, is temporarily stored in the condensate tank 14, and is sent to the hot water service tank 4 by the condensate pump 5. - 特許庁

The hot water L8 in the hot water service tank 4 is transferred to the heat medium transfer pipe 410 as the hot water L1 by the pressurized water supply pump 3 . The hot water L1 transferred by the pressurized water supply pump 3 absorbs heat from the underground heat again in the deep part where the geotropical zone U exists, and is heat-exchanged. The heat-exchanged hot water L2 is transferred by the pressurized water supply pump 3 through a heat medium transfer pipe 410, which will be described later.
It should be noted that the present invention can also be applied to a plurality of heat medium transfer pipes (410a to 410f) in power generation equipment such as the binary generators A to B of the second to fifth embodiments described above.

As shown in FIG. 21 , the heat medium transfer pipe 410 includes a plurality of heat medium transfer pipes (410a to 410f) installed from the ground surface S to the geotropical zone U. As shown in FIG. A heat medium transfer pipe 410f will be described as a representative example of the heat medium transfer pipes 410 (410a to 410f) with reference to FIG.
In the geothermal power generation system 400, the medium injection pipe 50 absorbs the underground heat of the geothermal heat U, heat-exchanges with hot water (L2) as a heat medium, and transfers the hot water (L3) to the ground. If the temperature of the transfer promoting medium 39 drops due to reasons such as when the heat in the geothermal heat U near the pipe 50 does not recover, the flow path switching valve 413 provided on the ground side of the heat medium transfer pipe 410f and the flow A structure is adopted in which water as a heat medium is circulated in the heat medium transfer pipe 410f reaching the geotropical zone U by switching the path switching valve 414 .

When the hot water L3 is circulated within the heat medium transfer pipe 410f, a pumping pump 411 is provided for applying pressure to circulate the hot water so that it does not boil. In addition, the geothermal power generation system 400 circulates through the paths of the plurality of heat medium transfer pipes 410 by applying pressure by the pressurized water supply pump 3 so as not to boil even during normal power generation. When one unit is not enough, the compressing pump 411 is used. The pressure-feeding pump 411 plays a role of pressure regulation so that the pressure in the heat medium transfer pipe 410f is constant.

By applying pressure in the heat medium transfer pipe 410f to prevent boiling and circulating the hot water in the heat medium transfer pipe 410f as a single-phase flow, the hot water is circulated in the gas-liquid two-phase flow in the heat medium transfer pipe 410f. It is possible to effectively absorb heat from the geotropical zone U as compared with the case of circulating inside.

The heat medium transfer pipe 410f includes a circulation sensor section 412 provided with a temperature sensor and a pressure sensor for measuring the temperature and pressure of the hot water L3 in the middle of the circulation path. Even if the heat medium transfer pipe 410f does not generate power due to an unexpected temperature drop in the geotropical zone U due to periodic maintenance or a natural disaster, the temperature of the hot water is kept uniform by the pressure control valve PV1. Since the temperature of the circulated hot water can be made uniform by circulating the water including the geotropical zone U so that the Even if the temperature is not known, it is possible to estimate the temperature state of the geotropical zone U and use it as an index for planning the amount of power generation.

(Technical features conceivable from the above embodiment)
Examples of technical features of the present embodiment are shown in parentheses below, but they are not particularly limited, but merely illustrative, and the effects conceivable from these features will also be described.
<First feature point>
A heat medium transfer pipe (for example, mainly a heat medium transfer pipe 10 (medium injection pipe 50 , heat medium take-out pipes 80) 410 and 500), wherein the heat medium transfer pipes are pipe joints (for example, mainly pipe screw joints 51 and 55) that connect a plurality of the heat medium transfer pipes. , a heat medium heat insulating pipe (for example, mainly heat insulating pipe 60, 90), and

Due to the above features, the present invention not only improves the heat retaining performance of the heat medium transfer pipe by the heat retaining pipe, but also facilitates the replacement of the heat medium heat retaining pipe itself and the installation of the heat medium transfer pipe.

<Second feature point>
The heat medium heat retaining pipe includes an insertion pipe (e.g., mainly insertion pipes 61 and 91) inserted into the heat medium transfer pipe, and a diameter larger than the inner diameter of the heat medium transfer pipe. and projections (mainly projections 62 and 92, for example) held inside.
Due to the above features, the present invention facilitates the work of replacing the heat medium heat insulating pipe itself and installing the heat medium transfer pipe.

<Third characteristic point>
The heat medium transfer pipe is provided in the vicinity of a threaded portion where the heat medium transfer pipe is screwed and connected with the pipe joint when the heat medium transfer pipe is connected by the pipe joint, and a grip portion (for example, a main grip) that grips the heat medium transfer pipe. and a coating layer (e.g., mainly coating layers 46 and 86) coated with a heat insulating material provided to avoid the gripping portion, and the heat medium heat insulating pipe is provided with at least the gripping portion It is characterized by comprising the insertion tube extending to the portion of
According to the above features, the present invention improves the heat retention performance of the heat medium transfer pipe by the heat medium heat retention pipe of the connection pipe without impairing the performance of the connection work of the heat medium transfer pipe. Also, the heat medium transfer pipe can take out the medium from the ground without being deprived of heat.

<Fourth characteristic point>
The heat medium transfer pipes include a medium injection pipe (for example, mainly a medium injection pipe 50) that transfers the medium into the ground, and a medium extraction pipe (for example, a main and a heat medium take-out pipe 80), and the medium injection pipe and the medium take-out pipe are provided with the heat medium heat retaining pipes.

According to the above features, the present invention improves the heat retention performance of the medium injection pipe and the heat medium transfer pipe by means of the heat medium heat insulating pipe. The heat medium transfer pipe can take out the medium from the ground by the medium take-out pipe without being deprived of heat.

<Fifth characteristic point>
A generator that generates electricity using the heat of the medium taken out to the ground (for example, mainly a generator G or a binary generator B) and an absorption area where the medium absorbs the heat at the temperature necessary for power generation , a concrete heat-insulating layer (e.g., mainly geothermal cement) that insulates the heat-insulating area for retaining the heat of the medium during transportation with cement that hardens the side wall of the hole excavated during excavation, and the medium-injection pipe and pipe joint. A second coating layer (e.g., mainly insulating material 70) coated with an insulating material around and maintaining a pressure equal to or higher than the saturated vapor pressure at the desired temperature of the medium and transporting the medium without changing the phase state of the medium and a pressure pump (for example, mainly a pressurized water supply pump 5).

Due to the above features, the heat medium transfer pipe can take out the medium from the ground by the medium take-out pipe without being deprived of heat, so it is possible to generate power using the geothermal heat itself.

<Sixth characteristic point>
A pipe joint covering portion (for example, mainly a pipe threaded joint covering portion 93) is provided for covering from the outside so as to cover the entire pipe joint after the heat medium transfer pipes are connected to each other by the pipe joint. and
Due to the above features, the heat medium transfer pipe can block the heat transfer in the pipe joint portion by the pipe joint covering portion.

<Seventh characteristic point>
A heat medium transfer pipe (e.g., mainly heat medium transfer pipe 10 (medium injection pipe 50, heat medium extraction pipe 80) 410 for transporting the medium underground and recovering the medium that has absorbed heat in the ground. 500), in which underground water entering from between the heat medium transfer pipe and a tubular protection pipe (for example, the third protection pipe 33) provided on the outer periphery of the heat medium transfer pipe convects vertically. It is characterized by providing a plurality of convection blockers (for example, mainly the convection block board 73) for blocking the convection in the vertical direction.

Due to the above features, the convection blocking part prevents the hot water that has entered the gap between the heat medium transfer pipe and the protection pipe from below from mixing with the low temperature water above due to convection and turning into low temperature water. As a result, the heat retention performance of the heat medium transfer pipe is further enhanced.

<Eighth feature point>
An annular convection shielding member positioned below a pipe joint connecting the heat medium transfer pipes and having an inner diameter larger than an outer circumference of the medium transfer pipe and smaller than an outer diameter of the pipe joint. Characterized by
Due to the above features, the present invention has a structure that does not come out upward due to the hydraulic pressure of groundwater, etc., and improves workability during installation.

<Ninth characteristic point>
A heat medium transfer pipe that conveys a medium into the ground and recovers the medium that has absorbed heat in the ground,
A plurality of protective tubes (for example, mainly the first protective tube 31, the second protective tube 32, and the third protective tube 33) provided on the outer periphery of the heat medium transfer tube, the protective tube and the other protective tubes A heat insulating layer (for example, mainly foamed concrete 36, 37) provided between them, and a sealing layer (for example, mainly closed portions 34, 35) below the heat insulating layer to prevent groundwater from entering from below. characterized by

Due to the above features, the sealing layer prevents water having a temperature lower than that of the heat medium transfer pipe from entering from below, thereby improving the heat insulating performance of the heat medium transfer pipe.

<Tenth Characteristic Point>
The heat insulating layer is characterized in that it is formed from a light base material or concrete containing many air bubbles.
Due to the above features, the present invention not only prevents water from entering, but also improves the heat insulating performance by containing a large amount of air and the like.

<Eleventh Characteristic Point>
9. The heat medium transfer pipe according to claim 8, wherein the sealing layer is made of concrete.
According to the above features, the present invention can prevent the infiltration of water by the sealing layer and prevent the temperature drop of the heat medium transfer pipe due to the infiltration of groundwater.

<Twelfth characteristic point>
A heat medium transfer pipe (for example, mainly a heat medium transfer pipe 10 (medium injection pipe 50, a plurality of heat medium extraction pipes 80), 410, 500), a geothermal power generation system for generating electricity using the heat of the recovered medium, wherein the medium is circulated in the heat medium transfer pipe medium 2, a switching valve (for example, mainly a flow switching valve 414) that switches the flow path of the medium, and a pressure adjustment device that circulates the medium while maintaining the pressure at a predetermined pressure without changing the state of the medium ( For example, a pressure feed pump 411) is mainly provided, and when the temperature of the medium drops, the switching valve and the pressure adjustment device are driven, and the heat medium transfer pipe medium is pumped until the temperature of the medium recovers. The medium is circulated inside.

According to the above features, the present invention circulates as a gas-liquid two-phase flow by applying pressure in the heat medium transfer pipe to prevent boiling and circulating the hot water in the heat medium transfer pipe as a single-phase flow. It is possible to absorb heat from the geotropic U more efficiently than the

<Thirteenth characteristic point>
A temperature measuring device (for example, mainly a circulation sensor unit 412 (temperature sensor)) for measuring the temperature of the medium is provided in the path for circulating the medium.
With the above features, even if the temperature of the geotropical zone is unknown, the present invention circulates the hot water including the geotropical zone so that the temperature of the hot water becomes uniform, and measures the temperature of the circulated hot water. Since it can be measured by a device, it can be used as an indicator of whether the temperature in the geotropical zone has recovered.

<14th characteristic point>
A heat medium transfer pipe (for example, mainly a heat medium transfer pipe 10 (medium injection pipe 50, heat medium extraction pipes 80), 410, 500), a method of constructing a first sealing layer (e.g., , mainly the closed portion 35), and a first protective tube burying step of burying the first protective tube (for example, mainly the first protective tube 31) in the hole formed in the first sealing process. and, after the first sealing layer is stabilized, the first sealing layer is drilled with a smaller diameter than the hole in the first sealing layer, and cement is poured into the drilled hole to seal the drilled hole. A second sealing step of forming a second sealing layer (for example, mainly the closed portion 34), and embedding a second protective tube (for example, mainly the second protective tube 32) in the hole formed by the second sealing step After the step of burying the second protective tube and the second sealing layer is stabilized, the second sealing layer is drilled with a smaller diameter than the hole in the second sealing layer, and the drilled hole is filled with the third protection. A third protective pipe burying step of burying a pipe (for example, mainly the third protective pipe 33), between the first protective pipe and the second protective pipe, and between the second protective pipe and the third protective pipe After the heat insulating layer forming step of pouring foamed concrete (for example, mainly foamed concrete 36, 37) between and the step of burying the third protective pipe, excavation is performed with a diameter smaller than the hole of the third protective pipe. and a heat medium transfer pipe burying step of burying the heat medium transfer pipe in the excavated hole.

With the features described above, the present invention prevents entry of water having a temperature lower than that of hot water flowing through the heat medium transfer pipe from below, and improves the heat insulating performance of the heat medium transfer pipe.

<Fifteenth characteristic point>
A heat medium transfer pipe (for example, mainly a heat medium transfer pipe 10 (medium injection pipe 50 , a plurality of heat medium extraction pipes 80), 410, 500), and a geothermal power generation method for generating power using the heat of the recovered medium, the rock existing in the geotropics (for example, mainly the rock zone 38) is provided with an insertion hole that is a hole formed with a diameter larger than that of the heat medium transfer pipe, a transfer promoting medium (for example, mainly the transfer promoting medium 39) and the heat medium transfer pipe are inserted into the insertion hole, The heat of the geotropical zone is transferred to the heat medium transfer pipe via a transfer promoting medium.

With the above features, the present invention can efficiently dissipate the heat of the geotropical zone by interposing an intermediary substance between the heat medium transfer pipe and the geotropical zone even if the geotropical zone is a bedrock zone or a fractured zone with poor heat transfer. Absorption is possible.

<Sixteenth Characteristic Point>
Equipped with a plurality of heat medium transfer pipes for transporting a medium (mainly water, oil, etc.) underground and recovering the medium that has absorbed heat in the ground, and using the heat of the recovered medium to generate power A geothermal power generation method that includes an insertion hole that is a hole formed with a diameter larger than that of the heat medium transfer pipe in a fractured zone (for example, mainly a fractured zone 43) existing in the geotropical zone, and is inserted into the insertion hole and a medium container (receiving pipe 75) containing a transmission promoting medium (for example, mainly the transmission promoting medium 39, water, oil, etc.) is provided, the medium container is inserted, and the transmission contained in the medium container is provided. The heat of the geotropical zone is transferred to the heat medium transfer pipe through a promotion medium.

With the above features, the present invention can efficiently dissipate the heat of the geotropical zone by interposing an intermediary substance between the heat medium transfer pipe and the geotropical zone even if the geotropical zone is a bedrock zone or a fractured zone with poor heat transfer. Absorption is possible.

Another technical feature is that the media container is provided with a plurality of through holes (e.g., mainly media transfer holes 76). As a result, it is possible to protect the heat medium transfer pipe from collapse of the geotropical zone and maintain the state of heat transfer of the medium such as fluid in the geothermal zone to the heat medium transfer pipe.

The present invention is by no means limited to the above-described embodiments, and it goes without saying that various aspects can be implemented as long as they fall within the technical scope of the present invention.

As shown in the above embodiment, it can be used not only in geotropics where hot springs flow, but also in volcanic areas, underwater volcanic areas, and the like.

1, 200, 300, 400 ... geothermal power generation system,
1a, 1b, 1c... pressurized water generator, 3... pressurized water supply pump, 4... hot water service tank,
5... Condensate pump, 6... Condenser, 10 410 (a to f) 500... Heat medium transfer pipe,
27... Evaporation curve, 31... First protection tube, 32... Second protection tube, 40... Injection tube,
42, 82... Male screw portion, 33... Third protective tube, 34, 35... Foamed concrete,
36, 37 foamed concrete, 38 bedrock zone, 39 transmission promoting medium, 43 fracture zone,
50...Medium injection pipe, 51/55...Pipe threaded joint, 52/56...Female screw portion,
53, 57... Placement space portion, 46, 86... Coating layer, 47, 87... Grip portion,
60, 90... Thermal insulation tube, 61, 91... Insertion tube, 62, 92... Protrusion, 73... Convection shielding board,
75... Receiving pipe, 76... Medium moving hole, 80, 80a... Heat medium take-out pipe, 81... Take-out pipe,
85... Thermal insulation part, 93... Pipe screw joint coating part, 150... Heat exchange part, 151... Heat exchanger,
155... Circulation pump, 414... Flow path switching valve, 411... Pressure feed pump,
412... circulation sensor unit, T/T2/T3... steam turbine, G... generator,
B... binary power generator, CT... cooling tower, F... steam separator, TF... power receiving equipment,
S: surface, U: geotropic.

Claims (1)

A geothermal power generation system that includes a plurality of heat medium transfer pipes that convey a medium underground and recover the medium that has absorbed heat in the ground, and generates power using the heat of the recovered medium,
a pressure pump for pressure-feeding the medium into the plurality of heat medium transfer pipes;
a switching valve for switching a flow path of the medium so that the medium flows directly from the medium take-out pipe to the medium injection pipe in order to circulate the medium in each of the heat medium transfer pipes;
and individual pressure adjusting means for circulating the medium while maintaining the pressure at a predetermined pressure without changing the state of the medium in order to circulate within the individual heat medium transfer pipes,
A geothermal power generation system characterized in that, when the temperature of the medium drops, the switching valve and the pressure adjusting means are driven to circulate the medium in the heat medium transfer pipe until the temperature of the medium recovers. .

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