JP6587118B1 - Geothermal recovery device - Google Patents

Abstract

An object of the present invention is to provide a geothermal recovery device capable of efficiently recovering a heated fluid while suppressing a temperature drop of the fluid heated by the geothermal heat. An outer tube 12 and an inner tube 14 are embedded in the ground and communicated with each other at a lower portion, and a fluid flowing from the ground is heated by geothermal heat while passing through the outer tube 12 and the inner tube 14 and heated. The geothermal recovery apparatus 10 is a geothermal recovery apparatus that recovers geothermal heat by allowing the fluid to flow again to the ground, and the inner pipe 14 has a heat insulating portion 22 in a portion other than the lower part thereof. [Selection] Figure 1

Description

  The present invention relates to a geothermal recovery device, for example, a geothermal recovery device used for geothermal power generation.

  Geothermal power generation, which generates electricity using geothermal fluid that has become a high-temperature fluid by the rain and snow that has fallen on the ground surface penetrated deep underground, has no impact on the environment without requiring fossil fuels. Expectations are rising. Geothermal power generation is also attracting attention because it can use many volcanic zones in Japan and is not affected by the weather.

  This geothermal power generation includes the so-called flash method and dry steam method that generate electricity by rotating the turbine with hot water and steam pumped from the underground geothermal fluid reservoir, and heat pumped from the underground geothermal fluid reservoir. There is a so-called binary system that generates steam by heating an organic medium or the like having a low boiling point with water or steam, and rotating the turbine with the steam.

  On the other hand, as a geothermal recovery method, the hot water and steam pumped from the underground reservoir are not used as they are, but the geothermal heat is recovered by heating the fluid flowing in from the ground with geothermal heat and then flowing out to the ground again. A method has also been proposed.

  As an apparatus for recovering such geothermal heat, for example, it is an outer tube arranged in the ground, and is closed except for the opening on the ground side or the vicinity thereof, and several tens to upward from the bottom and the bottom. An outer tube in which fluid can exchange heat with external geothermal heat in an area of several hundred meters, and an inner tube disposed inside the outer tube, at least the bottom or its vicinity is open, and the bottom is the outer tube Has been proposed (see Patent Document 1), which includes an inner pipe positioned in the range of several tens to several hundreds of meters upward from the bottom of the base.

JP 2006-098806 A

  In the apparatus for recovering geothermal heat described in Patent Document 1, a fluid (hereinafter sometimes referred to as a heating fluid) flows from the outer tube and flows out from the inner tube. However, the inner tube has high thermal conductivity. Since it is made of stainless steel, there has been a problem that the heated fluid is cooled while it flows out to the ground through the inside of the inner pipe (a relatively low temperature range in the upper part).

  The subject of this invention is providing the geothermal recovery apparatus which suppresses the temperature fall of the fluid heated by geothermal heat and can collect | recover geothermal efficiently.

  In the study of means for efficiently recovering geothermal heat by suppressing the temperature drop of the heating fluid, the present inventors have provided a heat insulating part in a part of the inner pipe (part excluding the lower part), thereby It has been found that geothermal heat can be efficiently recovered by suppressing the temperature drop of the fluid heated by the above, and the present invention has been completed.

That is, the present invention is as follows.
[1] An outer pipe and an inner pipe that are buried in the ground and communicate with each other at the lower part are provided. The fluid flowing in from the ground is heated by geothermal heat while passing through the outer pipe and the inner pipe, and the heated fluid is again returned to the ground. A geothermal recovery device that recovers geothermal heat by flowing into
The geothermal heat recovery apparatus according to claim 1, wherein the inner pipe has a heat insulating portion in a portion excluding a lower portion thereof.
[2] The geothermal recovery apparatus according to the above [1], wherein the inner pipe has a heat insulating portion in a range where the underground temperature is 100 ° C. or lower.
[3] The geothermal recovery apparatus according to the above [1] or [2], wherein the inner pipe has a communication opening communicating with the outer pipe at a lower side portion thereof.
[4] The geothermal recovery apparatus according to the above [3], wherein the bottom of the inner pipe is closed.
[5] The geothermal recovery device according to the above [3] or [4], wherein the communication opening on the lower side is provided in a range of 0.5 to 5 m from the lower end of the inner tube.
[6] The geothermal recovery device according to any one of [1] to [5], wherein the lower end of the inner pipe is located in a range of 0 to 10 m from the inner bottom surface of the outer pipe.
[7] The geothermal recovery device according to the above [6], wherein the lower end of the inner tube is positioned so as to contact the inner bottom surface of the outer tube.

[8] A geothermal recovery device in which a fluid flowing from the ground flows out from the outer tube to the ground through the inner tube,
The geothermal recovery apparatus according to any one of the above [1] to [7], wherein the outer tube has a heat insulating part in a range where the underground temperature is 100 ° C or lower.
[9] The geothermal recovery device according to any one of [1] to [8] above,
A generator for generating electricity using the fluid flowing out of the geothermal recovery device;
A geothermal power generation system characterized by comprising:
[10] The geothermal power generation system according to [9], wherein the power generator generates power by rotating the turbine with the fluid flowing out from the geothermal recovery device.
[11] The geothermal power generation system according to [9], wherein the power generator generates power by rotating the turbine with the working fluid heated by the fluid flowing out from the geothermal recovery device.

  According to the geothermal recovery device of the present invention, it is possible to efficiently recover geothermal heat while suppressing the temperature drop of the fluid heated by geothermal heat.

It is a schematic sectional drawing for demonstrating the geothermal recovery apparatus which concerns on the 1st Embodiment of this invention. It is a schematic sectional drawing for demonstrating the geothermal recovery apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic sectional drawing for demonstrating the geothermal recovery apparatus which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows the outline of a structure of the geothermal power generation system of the system which directly utilizes the heating fluid provided with the geothermal recovery apparatus of this invention for electric power generation. It is explanatory drawing which shows the outline of a structure of a binary system geothermal power generation system provided with the geothermal recovery apparatus of this invention.

  The geothermal recovery apparatus of the present invention includes an outer pipe and an inner pipe that are buried in the ground and communicate with each other at the lower part, and heats the fluid flowing from the ground by geothermal heat while passing through the outer pipe and the inner pipe, A geothermal recovery device that recovers geothermal heat by causing a fluid to flow again to the ground, wherein the inner pipe has a heat insulating portion in a portion other than the lower portion thereof.

  In the geothermal recovery apparatus of this invention, the temperature fall at the time of the fluid heated with geothermal heat flowing out on the ground can be suppressed, and geothermal heat can be collect | recovered efficiently. Further, since the geothermal recovery apparatus of the present invention does not directly recover the underground hot water and steam, resources such as hot springs are not exhausted, and scales such as sulfur adhere to the apparatus. Therefore, the cost for maintenance and the like is low, and it can be used for a long time.

  The geothermal recovery device of the present invention allows a heating fluid to flow from an inner pipe or an outer pipe buried in the ground, and at least a heating fluid in a reservoir (high temperature portion) of an underground geothermal fluid having an underground temperature of 100 ° C. or higher. Is heated to flow out to the ground again through the outer tube or the inner tube to recover the geothermal heat. That is, at least the outer tube has a structure reaching the geothermal fluid reservoir. For example, the geothermal fluid reservoir is preferably an underground temperature of 100 ° C or higher, more preferably 120 ° C or higher, and further 150 ° C or higher. preferable. As the heating fluid used in the geothermal recovery apparatus of the present invention, water, an organic medium having a boiling point of 100 ° C. or less, and the like can be preferably exemplified.

(Outer pipe)
The outer pipe in the geothermal recovery apparatus of the present invention is buried in the ground and communicates with the inner pipe in the lower part. Examples of the cross-sectional shape of the outer tube include various shapes such as a square, a rectangle, and a circle. A circular shape is preferable. The outer tube is closed at the bottom and sides.

  Further, the outer tube may be entirely buried in the ground, but a part of the outer tube may be provided on the ground. That is, the outer pipe may be provided from the ground to the ground.

  The material of the outer tube is not particularly limited as long as it is a material having thermal conductivity, and examples thereof include iron, stainless steel, and carbon steel. Points such as thermal conductivity, durability, cost, etc. Therefore, stainless steel is preferable. Moreover, the periphery of the outer tube may be partially or entirely covered with concrete or the like, thereby improving durability.

  Further, the length of the outer tube may be any length as long as it reaches at least the reservoir (high temperature portion) of the geothermal fluid, and can be appropriately determined depending on the installation location. As the length of the outer tube, for example, it is preferable that the length is 100 m or more in the range of the underground temperature 100 ° C. or more, and the length is 100 m or more in the range of the underground temperature 120 ° C. or more. More preferably, the length is more than 100 m in the range of the underground temperature of 150 ° C. or more.

  The diameter of the outer tube can accommodate at least the inner tube and can be appropriately set depending on the installation location. The inner diameter of the outer tube is, for example, 50 to 500 mm, preferably 80 to 300 mm, more preferably 100 to 300 mm, and still more preferably 150 to 300 mm. When the inner diameter of the outer tube is within this range, the heating fluid is sufficiently retained in the high temperature portion in the ground, and the heating fluid can be sufficiently heated.

  The upper end of the outer pipe has an inlet / outlet through which fluid can flow in or out on the ground. This inlet / outlet is connected to a circulation pump for circulating fluid, a part of a geothermal power generation system such as a heat exchanger, and the like.

(Inner pipe)
The inner pipe in the geothermal recovery apparatus of the present invention is provided inside the outer pipe buried in the ground, and communicates with the outer pipe at the lower part thereof. Examples of the cross-sectional shape of the inner tube include various shapes such as a square, a rectangle, and a circle. A circular shape is preferable.

  The diameter of the inner tube is, for example, 10 to 400 mm, preferably 30 to 200 mm, more preferably 30 to 150 mm, and still more preferably 30 to 100 mm. The ratio of the volume of the inner tube to the volume of the outer tube excluding the inner tube is preferably 1: 1.5 to 100, more preferably 1: 2 to 80, from the viewpoint that the heating fluid can be efficiently heated. 1: 20-50 is more preferable.

  Further, the inner pipe may be entirely buried in the ground, but a part thereof may be provided on the ground. That is, the inner pipe may be provided from the ground to the ground.

  As described above, the inner pipe communicates with the outer pipe at the lower part thereof. As the communication form, for example, the inner pipe is open at the bottom, or the lower part of the inner pipe is connected to the outer pipe. The form which has the communication opening which connects is mentioned. The communication opening can be provided at the bottom and / or side of the inner tube. Specifically, for example, a form having a hole and / or a slit in the closed bottom of the inner pipe, a form having a hole and / or a slit in the lower side of the inner pipe (the bottom is closed or open), and the inner pipe The closed bottom portion and the lower side portion of the inner tube may be provided with holes and / or slits, and the inner tube bottom portion is closed and the inner tube lower side portion is provided with the holes and / or slits. preferable. By closing the bottom of the inner tube and forming a hole and / or slit in the lower side to allow fluid to flow, it is possible to prevent filth from flowing into the inner tube. In the case of a form having holes and / or slits on the lower side portion of the inner tube, the holes and / or slits are preferably provided within a range of 0.5 to 5 m from the lower end of the inner tube, for example. More preferably, it is provided within a range of 8 to 3 m. Thereby, durability of the lower part of high heat can be improved and a deformation | transformation of an inner pipe | tube can be prevented. Moreover, the inflow of the filth collected at the bottom of the outer tube to the inner tube can be further prevented.

  The lower end of the inner pipe is preferably located in the geothermal fluid reservoir (high-temperature part), and is preferably located, for example, in the range of 0 to 150 m from the inner bottom surface of the outer pipe, depending on the installation location. More preferably, it is located in the range of 0 to 80 m from the inner bottom surface of the outer tube, more preferably in the range of 0 to 10 m, particularly preferably in the range of 0 to 5 m. Most preferably, it is located in contact with the bottom surface. Thereby, the fluid for heating of the deepest part (inside the lower end of an outer tube) which becomes the highest temperature is recoverable.

  The inner pipe of the present invention has a heat insulating part in a portion excluding the lower part thereof. The heat insulating part may have a structure in which a part of the inner tube itself has a heat insulating structure, or may have a structure in which a heat insulating member is provided around the inner tube. Examples of the configuration in which a part of the inner pipe itself has a heat insulating structure include a structure in which a part of the pipe has a heat insulating double structure and a structure in which a part of the pipe is made of a heat insulating material. it can. Examples of the heat insulating member provided around the inner tube include glass wool, heat resistant foamed polystyrene, and heat resistant foamed urethane.

  It is preferable that the heat insulation part of the said inner pipe is provided in the range whose underground temperature is 100 degrees C or less, and it is more preferable that it is provided in the range of 120 degrees C or less. As a result, when the heating fluid flows in from the outer pipe and flows out from the inner pipe to the ground, heat transfer from the lower temperature fluid flowing in the surrounding outer pipe is cut off, and the temperature of the fluid flowing in the inner pipe decreases. Can be suppressed. Also, in the case of a system in which the heating fluid flows in from the inner pipe and flows out from the outer pipe to the ground, heat transfer from a lower temperature fluid flowing in the inner pipe is cut off, and the temperature drop of the fluid flowing in the outer pipe is suppressed. be able to. For example, since the heating fluid can be maintained at 100 ° C. or higher, it can be recovered in a gas state suitable for the heat medium.

  The material other than the heat insulating portion of the inner pipe is not particularly limited as long as it has thermal conductivity, and examples thereof include iron, stainless steel, and carbon steel. Thermal conductivity, durability, Stainless steel is preferable from the viewpoint of cost and the like.

  The length of the lower part of the inner pipe (the part not having the heat insulation part) is a geothermal fluid reservoir (high temperature part) having an underground temperature of 100 ° C. or higher (preferably 120 ° C. or higher, more preferably 150 ° C. or higher). ) Can be determined as appropriate. The length is, for example, 1 to 200 m. The upper limit of the length depends on the length of the outer tube present in the geothermal fluid reservoir. On the other hand, the lower limit of the length may be a length that secures a region in which the communication opening is provided in the lower side portion. The longer the lower part of the inner pipe is, the more the heating fluid can absorb the heat from the geothermal fluid reservoir of the heating fluid. It tends to be possible to recover a heating fluid having a stable temperature without any problems. Therefore, the length of the lower part of the inner tube is preferably about 5 to 70 m, and more preferably about 10 to 60 m.

  The upper end of the inner pipe has an inlet / outlet through which fluid can flow in or out on the ground. This inlet / outlet is connected to a circulation pump for circulating fluid, a part of a geothermal power generation system such as a heat exchanger, and the like.

  In the geothermal recovery apparatus of the present invention, when the heating fluid flows from the inner pipe and flows out from the outer pipe to the ground, the outer pipe has a heat insulating portion in the range where the underground temperature is 100 ° C. or less. It is preferable. Thereby, when the heated fluid passes through the outer pipe (flows out to the ground), a temperature drop due to heat transfer from the low temperature underground can be suppressed. The structure of the heat insulation part of the outer tube is the same as that of the heat insulation part of the inner tube.

Subsequently, a geothermal power generation system using the above-described geothermal recovery apparatus of the present invention will be described.
The geothermal power generation system of the present invention includes the above-described geothermal recovery device and a generator that generates power using the fluid that has flowed out of the geothermal recovery device.

  The geothermal power generation system of the present invention can be applied to various geothermal power generation such as a system that directly uses a heating fluid for power generation or a so-called binary system that indirectly uses a heating fluid for power generation. Specifically, for example, when adopting a method of directly using a heating fluid for power generation, the geothermal power generation system of the present invention generates power by rotating the turbine with the above-described geothermal recovery device and the fluid flowing out of the geothermal recovery device. A power generation system including a generator. When the binary system is adopted, the geothermal power generation system of the present invention includes the above-described geothermal recovery device and a generator that generates electricity by rotating the turbine with the working fluid heated by the fluid flowing out of the geothermal recovery device. It is a power generation system.

  Hereinafter, embodiments of the geothermal recovery apparatus of the present invention will be specifically described with reference to the drawings, but the present invention is not limited to these embodiments.

  Here, FIG. 1 is a schematic cross-sectional view for explaining the geothermal recovery apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view for explaining a geothermal recovery apparatus according to the second embodiment of the present invention. FIG. 3 is a schematic cross-sectional view for explaining a geothermal recovery apparatus according to the third embodiment of the present invention.

  As shown in FIG. 1, a geothermal recovery device 10 according to the first embodiment of the present invention includes an outer tube 12 and an inner tube 14 that are embedded in the ground and communicate with each other at a lower portion. The geothermal recovery device 10 is a device in which a heating fluid flows from the outer tube 12 to the inner tube 14.

  The outer tube 12 is, for example, a stainless steel cylindrical body that extends from the ground having an inner diameter of about 200 mm and a length (depth) of about 450 m from the ground to the tropics (high temperature portion). The outer tube 12 is closed at the bottom and sides, and has an inlet 16 at the upper end. The inflow port 16 is connected to a circulation pump 18 or the like for circulating a fluid in the geothermal recovery device 10. The periphery of the underground outer tube 12 is covered with a concrete material 20.

  The inner pipe 14 is provided inside the outer pipe 12 and is a cylindrical body that extends from the ground to the earth tropics (high temperature part). The inner tube 14 has an inner diameter of about 35 mm, and a central portion (for example, about 400 m) from the upper portion is constituted by a heat insulating double tube 22 (heat insulating portion). Further, the steel pipe 24 made of stainless steel is constituted by about 50 m up to the bottom of the lower part.

  The heat insulation double pipe 22 is provided at least in the range where the underground temperature is 100 ° C. or less from the ground (low temperature part, middle temperature part), and can block heat transfer inside and outside the inner pipe 14 in this range. The steel pipe 24 is provided in a range where the underground temperature is 100 ° C. or higher (high temperature part) and has high thermal conductivity, and thus the inner pipe 14 in this range is easy to transmit heat from the outside.

  The bottom end of the inner tube 14 is closed at the bottom, and is provided in contact with the inner bottom surface 26 of the outer tube 12. The inner tube 14 has a plurality of holes 28 communicating with the outer tube 12 in a range of about 1 m on the lower side (a range of 0.5 to 1.5 m from the lower end). The inner pipe 14 has an outlet 30 at the upper end thereof. The outlet 30 is connected to a power generation system such as a power generator 32 outside the geothermal recovery device 10.

  Next, the geothermal recovery device 34 according to the second embodiment will be described. In addition, about the member of the structure similar to the geothermal recovery apparatus 10 which concerns on the said 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. In the present embodiment, the bottom surface of the lower end of the inner tube 36 is opened, and the lower end of the inner tube 36 is different from the above example in that it does not contact the inner bottom surface of the outer tube 38.

  As shown in FIG. 2, the geothermal recovery device 34 according to the second embodiment of the present invention includes an inner tube 36. The lower part (parts other than the heat insulation double pipe) of the inner pipe 36 is constituted by a steel pipe 40 made of stainless steel having a length of about 11 m, for example. The bottom end of the inner tube 36 has an open bottom surface, and is provided at a position separated from the inner bottom surface 42 of the outer tube 38 by, for example, about 40 m.

  Next, a geothermal recovery device 44 according to the third embodiment will be described. In addition, about the member of the structure similar to the geothermal recovery apparatus 10 which concerns on the said 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. In the present embodiment, the outer tube 46 has a heat insulating portion 48 in a range where the underground temperature is 100 ° C. or less, and the heating fluid flows from the inner tube 14 and flows out from the outer tube 46 to the ground. This is different from the first embodiment.

  As shown in FIG. 3, the geothermal recovery device 44 according to the third embodiment of the present invention includes an outer tube 46. The outer tube 46 has a central portion (for example, about 400 m) from the upper portion, and is constituted by a heat insulating double tube 48 (heat insulating portion). Further, the steel pipe 50 made of stainless steel is formed about 50 m up to the bottom of the lower part. Thereby, the temperature fall from the low temperature underground part of the fluid heated by the geothermal heat which flows through an outer pipe | tube can be suppressed, and it can collect | recover efficiently.

  A geothermal power generation system including the above-described geothermal recovery device of the present invention will be specifically described with reference to the drawings. FIG. 4 is an explanatory diagram showing an outline of the configuration of a geothermal power generation system using a heating fluid including the geothermal recovery device of the present invention directly for power generation. FIG. 5 is an explanatory diagram showing an outline of the configuration of a so-called binary type geothermal power generation system including the geothermal recovery device of the present invention.

  As shown in FIG. 4, the geothermal power generation system 100 of the present invention includes a geothermal recovery device 10, a separator, a turbine, a generator, a condenser, a water storage tank, and a circulation pump. The geothermal power generation system 100 of the present invention generates electricity by rotating a turbine with a heating fluid heated by geothermal heat recovered by the geothermal recovery device 10.

  As shown in FIG. 5, the geothermal power generation system 200 of the present invention is a so-called binary system, a heating fluid circuit in which the heating fluid of the geothermal recovery device 10 circulates, and the heating fluid that is heated by the heating fluid. The working fluid circuit in which the working fluid that rotates the fluid circulates is provided. In the geothermal power generation system 200 of the present invention, heat exchange is performed by an evaporator. For example, the working fluid having a lower boiling point than the heating fluid is used as steam, and the turbine is rotated to generate power.

  Since the geothermal recovery apparatus of the present invention can be used for geothermal recovery of geothermal power generation, it is industrially useful.

DESCRIPTION OF SYMBOLS 10 Geothermal recovery apparatus 12 Outer pipe 14 Inner pipe 16 Inlet 18 Circulation pump 20 Concrete material 22 Heat insulation double pipe (heat insulation part)
24 Steel pipe 26 Internal bottom surface 28 Hole 30 Outlet 32 Generator 34 Geothermal recovery device 36 Inner tube 38 Outer tube 40 Steel tube 42 Internal bottom surface 44 Geothermal recovery device 46 Outer tube 48 Heat insulation double tube (heat insulation part)
50 Steel pipe 100 Geothermal power generation system 200 Geothermal power generation system

Claims (4)

It has an outer pipe and an inner pipe that are buried in the ground and communicate with each other at the lower part. The fluid flowing in from the ground is heated by geothermal heat while passing through the outer pipe and the inner pipe, and the heated fluid is discharged to the ground again. A geothermal recovery device that collects geothermal heat,
The inner tube is
While have a heat insulating portion on the portion except the lower portion, the portion other than the heat-insulating portion has a thermal conductivity,
The lower end is positioned so as to contact the inner bottom surface of the outer pipe,
The bottom is closed, and the lower side has a communication opening communicating with the outer tube.
The geothermal recovery device , wherein the communication opening is provided within a range of 0.5 to 5 m from the lower end of the inner pipe . A geothermal recovery device according to claim 1 ;
A generator for generating electricity using the fluid flowing out of the geothermal recovery device;
A geothermal power generation system characterized by comprising: The geothermal power generation system according to claim 2 , wherein the generator generates electricity by rotating the turbine with the fluid flowing out from the geothermal recovery device. The geothermal power generation system according to claim 2 , wherein the generator generates electricity by rotating the turbine with the working fluid heated by the fluid flowing out from the geothermal recovery device.