JP2014202149A - Geothermal power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a geothermal power generation system capable of being used even in a winze at a low shaft bottom temperature, a winze at a small boring depth or at a location at which it is difficult to secure cooling water, lessening the influence of surrounding hot springs and scale adhesion, reducing cost relating to medium cooling and pumping, and achieving high efficiency and space saving installation.SOLUTION: A closed loop circulation type geothermal power generation system uses a coaxial double-pipe heat exchanger 1 by constituting a helical channel between an outer tube inner wall and an inner heat insulating tube of the coaxial double-pipe heat exchanger 1 for accelerating underground heat exchange by underground heat absorption of a power generation medium and formation of condensate liquid by underground heat radiation of the power generated medium, accelerating the condensed liquid formation by heat radiation into the underground and cooling by helical flow down of the medium in low-temperature underground layers such as a shallow constant-temperature layer and a water-bearing layer, and accelerating heat absorption from the underground and heating in high-temperature underground layers such as a deep high-temperature layer and a geothermal layer, thereby facilitating raising a temperature of the medium in a bottom portion of a double tube shaft.

Description

The present invention is a closed-loop circulation type using a coaxial double-tube heat exchanger that does not pump up hot springs or geothermal steam newly or increase in volume, and is capable of long-term stable operation without being affected by scale adhesion. The technical field of geothermal power generation systems.

In particular, by making it possible to efficiently absorb and dissipate heat in the power generation medium in the ground, it can also be used in wells with a shallow excavation depth and a relatively low bottom temperature, and well drilling and cooling equipment, and The present invention relates to a geothermal power generation system that efficiently generates power while reducing costs for securing cooling water and auxiliary power.

  Geothermal power generation, which generates electricity using hot spring heat, geothermal steam, or geothermal heat sources, uses the high-temperature magma layer of the earth as a heat source, and does not involve fuel consumption or greenhouse gas emissions during the power generation process. In recent years, it has attracted attention as a means of power generation that contributes to prevention of global warming.

In conventional geothermal power generation systems, a low-boiling medium is heated and evaporated by source hot springs and geothermal steam from a hot spring well, as well as a flash method in which water is injected by excavating geotropics and generating geothermal steam. Binary power generation systems that drive steam turbines are widely known.

However, when new well drilling is performed in the hot spring area to produce a large amount of geothermal steam and hot springs, or when the existing steam and hot spring volume is pumped up, the temperature of the surrounding hot springs decreases, the amount of hot spring discharge and groundwater Because there is a concern that the amount will decrease, it is necessary to establish a power generation system that efficiently uses only underground high-temperature geothermal heat without increasing the amount of new geothermal steam production or source pumping.

In general, hot springs and geothermal steam contain a large amount of calcium carbonate, etc., and are deposited as scales in source wells and geothermal steam production wells, as well as in flow paths and components in the power generation system, due to temperature changes and air contact. In addition, the flow path is blocked, resulting in a decrease in heat exchange efficiency or failure.

In recent years, as a technique for solving these problems, closed loop circulation type geothermal power generation described in Patent Document 1 has been proposed. This technology uses pressurized water as a medium and pressurizes and injects water to the tropics, which is the heat source, to generate steam and generate electricity, so it is possible to simultaneously reduce the two risks of impact on existing hot springs and failure due to scale adhesion. It is an excellent symbiotic geothermal power generation technology.

JP 2011-52621 A

As described above, according to the prior art, although it is possible to generate electricity through direct use of geothermal heat, which can greatly reduce the impact on surrounding hot springs and the risk of scale adhesion, there are five problems to be solved.

One is to collect geothermal heat intensively in the high-temperature tropics, so it is necessary to excavate to a high-temperature geothermal layer several kilometers below the ground, and to insert pressurized water injection pipes and heat insulation pipes for hot water extraction to this depth. In addition to increasing the drilling depth and piping, the cost of geothermal development and geothermal extraction is increased, and the piping material that performs heat exchange is required to have high heat resistance and heat insulation performance, which further increases the piping cost.

In addition, it is difficult to implement geothermal power generation using this method in existing wells that are generally several hundred meters below ground. There is a problem that the temperature of the geothermal layer decreases with continued water injection, and the medium temperature hardly rises with time.

In this way, the background of excavation over several kilometers underground and the medium temperature drop due to continued water injection tends to occur, while the heat exchange surface for raising the temperature of the medium is mainly limited to the bottom of the well in the high-temperature geothermal layer, The pressurized water flows down the double pipe vertically downward toward this endothermic part, so even though there is a high temperature layer up to the bottom of the well, sufficient heat exchange with the underground high temperature layer is possible. The low-temperature medium flows down to the bottom of the well without being performed.

In addition, in the prior art, since the medium after power generation is condensed on the ground and pressurized and injected, after being cooled sufficiently on the ground and condensed and liquefied, the pressure is increased with a pressure pump and underground injection is performed. In addition to the installation space and equipment cost associated with the above-ground cooling system, a large amount of cooling water is required, and the pressurizing power of the pressurizing pump is required, resulting in a decrease in net power generation.

In particular, there is a problem that a method for effectively utilizing the underground low-temperature layer is not clearly described in condensing liquid after power generation. In other words, the constant temperature layer from several meters to around a hundred meters is a geotropical zone where the underground temperature is constant between about 10 ° C and 15 ° C, regardless of the season, and the temperature of the constant temperature layer increases. However, although the underground temperature decreases in the aquifer where the groundwater and seawater flow, there is no clear method for using the underground cold in the shallow subsurface and aquifer for medium cooling.

In addition, as a means for efficiently cooling the medium after power generation, the cold power is taken out using the medium after power generation as an adsorption or absorption type refrigerator heat source, and the obtained cold heat is used to exit the refrigerator. Since a specific measure for further cooling the medium is not clearly described, there has been a problem that a large amount of equipment and cost are required for cooling and condensing the medium.

  In particular, in areas where there are abundant geothermal and geothermal fluids, it is difficult to procure a large amount of cooling water and produce cold heat. Therefore, a method for efficiently cooling the medium without using cold water as much as possible has been required.

  The present invention has been made in view of such problems, and its purpose is to be used in wells where the depth of excavation is shallow and the bottom temperature is low, and where it is difficult to procure a large amount of cold water. The impact on hot springs and the risk of scale adhesion are greatly reduced, and geothermal heat absorption and underground heat dissipation are efficiently performed, greatly reducing the costs associated with geothermal development and media cooling. It is to provide a new geothermal power generation system that enables high efficiency, low cost, and space-saving implementation by reducing auxiliary power.

In order to solve the above-mentioned problem, the invention described in claim 1
A closed-loop circulation type flow in which water, pentane, and other media are heated and raised by absorbing heat from high-temperature geothermal or geothermal fluid, cooled to condensate after use on the ground, and then absorbed again from geothermal or geothermal fluid. Of the underground heat exchangers that make up the road,
A coaxial double pipe composed of an outer tube that exchanges heat with the underground, and an inner heat insulating tube that raises the heated medium to the ground while insulating the heated medium. Furthermore, in the double pipe outer flow path formed in the gap between the inner wall of the outer pipe and the inner heat insulating pipe, in the underground heat exchange promotion part that promotes heat radiation to the ground or heat absorption from the ground By providing a spiral flow path constituting plate that spirals the flow path, heat exchange with the ground when the medium flows down in the ground is promoted.

The invention described in claim 2
The spiral flow path constituting plate according to claim 1 is made of a material having high heat conductivity and is fixed to an inner wall of a heat exchange promoting tube inserted in contact with the inner wall of the outer tube, or the heat exchange promoting By being integrally formed with the pipe, when the medium flows down the spiral flow path, heat exchange can be performed not only on the inner wall of the heat exchange promoting pipe but also on the spiral flow path constituting plate.

The invention according to claim 3
The spiral flow path component plate according to claim 1, which is made of a material having high heat conductivity, and is fixed to an outer wall of the inner heat insulation tube or integrally formed with the inner heat insulation tube. By inserting the heat insulating pipe so as to be in close contact with the inner wall of the outer pipe, when the medium flows down the spiral flow path, heat exchange can be performed not only on the inner wall of the heat exchange promoting pipe but also on the spiral flow path constituting plate. It is characterized by that.

The invention according to claim 4
In the spiral flow path according to claim 2 and 3, after adjusting the installation position of the spiral flow path component plate, the installation interval, and the inclination angle of the component plate based on the inner wall temperature distribution of the outer tube, By fixing or integrally molding, the heat absorption position and heat absorption amount from geothermal or geothermal fluid, or the heat radiation position and heat radiation amount to the underground low temperature layer or aquifer are controlled.

The invention described in claim 5
In the method for controlling the amount of underground heat exchange according to claim 4, the vertical distance between the plates of the spiral flow path constituting plate is narrowed in a region where the inner wall temperature of the outer pipe is higher than the medium temperature flowing down in the spiral flow path. Further, it is characterized in that heating of the medium flowing down the spiral flow path is promoted by either gradual inclination of the plate or a combination thereof.

The invention described in claim 6
In the method for controlling the amount of underground heat exchange according to claim 4, the vertical distance between the plates of the spiral flow path constituting plate is narrowed in a region where the inner wall temperature of the outer pipe is lower than the medium temperature flowing down in the spiral flow path. In addition, it is characterized in that cooling of the medium flowing down the spiral flow path is promoted by either gradual inclination of the plate or a combination thereof.

The invention described in claim 7
Both the underground heating promotion method according to claim 5 and the underground cooling promotion method according to claim 6 are arranged in a spiral flow path configuration type coaxial heat exchanger constituting a closed loop circulation flow path, and an outer pipe inner wall By applying according to the temperature distribution of the medium, the medium after power generation is directly pressed into the spiral flow path of the coaxial heat exchanger and condensed and liquefied in a constant temperature layer or a subsurface aquifer in the shallow underground. In addition, the temperature is preheated in the deep underground layer and in the tropical region, and then the temperature is lowered to the inner bottom surface of the outer tube that contacts the bottom of the deep geothermal layer to raise the inside of the inner heat insulating tube. Then, geothermal power generation is performed in a closed loop circulation channel in which a generator is driven by medium vapor on the ground, and the medium after power generation is pressed into the ground again.

The invention according to claim 8 provides:
A hot medium obtained by the closed-loop circulation channel according to claim 1 or a medium whose temperature is lowered by using the high-temperature medium for power generation or the like is used as a hot water or steam-driven adsorption or absorption refrigerator-driven heat source. The temperature of the medium is decreased by supplying the cooling medium, and the cooling medium obtained by using the medium as a driving heat source is used to cool the medium after driving the refrigerator.

According to the present invention, since the heat exchange efficiency in the underground and geothermal part of the heat exchanger composed of coaxial double pipes is greatly improved, even in a well having a shallow excavation depth and a low bottom temperature, Even in places where it is difficult to secure cooling water, it is possible to perform geothermal power generation with high efficiency and space saving while greatly reducing the impact on existing hot springs and the risk of scale deposition.

It is a mimetic diagram showing a schematic structure of a closed loop circulation type geothermal power generation system of a 1st embodiment concerning the present invention. It is a schematic diagram which shows the detail of the front end pipe | tube with a medium dropping nozzle connected and installed in the bottom of a spiral flow path type | mold coaxial heat exchanger which comprises the geothermal power generation system of FIG. It is a schematic diagram which shows the detail of arrangement | positioning of a medium dripping nozzle and an inner side heat insulation pipe | tube support part among the tip pipes with a medium dripping nozzle of FIG. Details of the heat exchange promoting tube integrally formed with the spiral channel constituting plate inserted into the heating promoting unit and the cooling promoting unit in the ground among the spiral channel constituting type coaxial heat exchanger constituting the geothermal power generation system of FIG. 1. It is a schematic diagram which shows. It is a schematic diagram which shows the detail of the spacer pipe | tube inserted in order to support a heat exchange promotion pipe | tube among the spiral flow path structure type | mold coaxial heat exchanger which comprises the geothermal power generation system of FIG. It is a schematic diagram which shows schematic structure of the closed loop circulation type geothermal power generation system of 2nd Embodiment which concerns on this invention.

The best mode for carrying out the present invention will be described below with reference to the drawings. The scope of the present invention is described in the scope of claims, and is not limited to this embodiment.

(First embodiment)

First, a schematic configuration and function of a closed-loop circulation geothermal power generation system using a spiral flow path configuration type coaxial heat exchanger according to a first embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the geothermal power generation system of the present invention is a closed-loop circulation flow path in which a power generation medium such as water or pentane circulates. It is composed of a heavy pipe heat exchanger 1 and a power generator 2 that generates power via a steam turbine using high-temperature and high-pressure medium steam obtained by geothermal heat absorption via this heat exchanger.

Further, the heat exchanger 1 includes a tip tube 3 with a medium dropping nozzle inserted into the bottom, an outer tube 4 welded to the tip tube 3 and inserted into the well, and a center of the connection surface of the tip tube A main part of the coaxial double pipe heat exchanger is constituted by the inner heat insulating tube 6 supported and fixed coaxially with the outer tube by the inner heat insulating tube supporting guide portion 5 arranged in the inner space.

Here, as shown in FIG. 2, the tip tube 3 with a medium dropping nozzle is manufactured of silicon carbide or the like having high heat resistance / corrosion resistance and heat conductivity in order to enhance durability and heat exchange efficiency in a high temperature geothermal layer. It is composed of a single-side closed tube or a single-side closed tube whose outer surface is coated with silicon carbide or the like. As shown in FIG. 3, the top surface of the tip tube is welded to a plurality of medium dropping nozzles 7 and a nozzle plate 8 having a guide portion 5 that supports an inner heat insulating tube that is coaxially installed on the upper portion.

In addition, the nozzle plate 8 has a channel area in the vertically downward direction for a medium preheated to a temperature lower by about 3 to 10 ° C. than the boiling point of the medium by underground heat through a coaxial double tube heat exchanger. It is made to flow down in a shower-like manner toward the inner wall of the bottom contact portion 9, that is, the bottom face of the end of the coaxial double-tube heat exchanger, through a plurality of smaller throttle passages, The medium has a function of accelerating the temperature-evaporation of the medium by the medium dispersion and dropping from a plurality of flow paths.

Further, the heat exchange is integrated with the silicon carbide spiral flow path constituting plate 10 shown in FIG. 4 so as to be in contact with the inner wall of the outer tube supported by the upper surface of the nozzle plate 8 and welded to the nozzle plate. The promotion tube 11 is inserted and installed. It is installed for the purpose of preheating the temperature of the medium sufficiently close to the boiling point in the flow down process until the medium reaches the tip tube 3 due to the underground heat absorption from the deep high temperature layer. To do.

On the other hand, in the region in contact with the isothermal layer and the low-temperature aquifer in the shallow underground, the inner wall temperature of the outer tube decreases due to heat exchange with the ground, and therefore, similar to the above-described underground heat absorption enhancement part, Spiral flow path component plate integral molding, heat exchange promoting tube 12 is inserted and installed to promote heat dissipation and cooling of the medium.
In addition, in order to suppress the heat conduction between the heat exchange promotion pipes while supporting the heat exchange promotion pipes inserted between the heat absorption promotion parts and the heat radiation cooling promotion parts, as shown in FIG. A spacer tube 13 made of a highly insulating material is inserted and installed.

Thus, in areas where heat exchange with the ground does not need to be promoted, by reducing the pressure loss as a linear flow path vertically downward using a spacer tube, the medium condensed and liquefied in particular in the heat radiation cooling promotion section If the flow path is configured to quickly flow down to the endothermic promotion portion with a small pressure loss and the medium is stored up to the liquid level 14 in the liquid state above the endothermic promotion portion, the pressure loss is reduced. It is possible to increase the pressure for flowing down the spiral flow path of the endothermic promotion portion that becomes higher, and thus it is possible to reduce the pump power for pumping the medium.

If it is difficult to pump the condensed liquid by this method, a small submerged pump for assisting the medium pumping may be installed in the outer straight flow path of the spacer tube 13.

  With the above configuration, the medium that has been efficiently absorbed by the deep high-temperature layer and the geothermal layer rises in the inner heat insulating pipe, and after driving the steam turbine connected to the generator on the ground, It becomes steam, and this is directly injected into the low temperature shallow constant temperature layer and the aquifer through the coaxial double pipe heat exchanger, and is condensed and liquefied and flows down to the deep high temperature layer again.

  In this way, the low-temperature and low-pressure steam directly injected from the ground is condensed and liquefied in the process of flowing down while radiating heat to the shallow constant temperature layer and the aquifer, so the inside of the spiral flow path is decompressed at the cooling promotion part of the coaxial double pipe Thus, the low-temperature low-pressure steam is sucked more efficiently and flows down in the spiral flow path. In other words, in this system, the functions of the cooling tower and the condenser found in general geothermal power generation are performed in the underground buried portion of the spiral flow path configuration type coaxial double pipe.

In this way, in one coaxial double tube heat exchanger that constitutes a closed-loop circulation flow path, the state change from condensation to liquefaction due to heat radiation cooling to the ground and evaporation to vaporization due to endothermic temperature rise from the ground, By configuring the flow path and underground heat exchange process to be performed along with the underground flow of the medium, the medium cooling device and cooling water are unnecessary or simplified, and at the same time, the heat exchange in the ground is promoted. It is possible to improve power generation efficiency by reducing auxiliary power and to save space by omitting incidental facilities.

  In order to condense and liquefy the medium in the ground and to efficiently heat and evaporate, it is essential to promote heat exchange in the ground. To achieve this, the outer tube of the coaxial double-tube heat exchanger is connected. After the insertion, the temperature distribution of the inner wall of the outer tube is measured, and based on the result, the region where the medium should be promoted for cooling and the region where the temperature rise should be promoted are specified. It is desirable to optimize the underground heat exchange in the spiral flow path by adjusting the installation angle.

  In addition, when the heat exchange promotion method described above still cannot extract the geothermal heat necessary for driving a steam turbine or the like, a vacuum pump or the like is provided in the closed loop circulation flow path including the coaxial double pipe heat exchanger. It is desirable to reduce the boiling point of the medium in the circulation flow path by using the reduced pressure so that the medium can be easily vaporized even with a small endothermic amount.

Also, for the outer tube of the coaxial double tube heat exchanger, it is desirable to coat the outer surface with a heat and corrosion resistant material such as silicon carbide in order to increase both the corrosion resistance and heat exchange efficiency in the ground. When a sufficient amount of heat exchange can be secured by optimizing the spiral flow path and the risk of underground corrosion is low, it is possible to reduce the cost by using a general steel pipe.

In addition, it is possible to use a vacuum heat insulating tube for the inner heat insulating tube, in order to maintain high heat insulating properties, but in addition to a double tube containing a vacuum heat insulating material, a pressure resistant, heat resistant and water resistant surface. It is also possible to construct a pipe with engineering plastics that are excellent and to weld and connect them.

As for the method of connecting the outer pipe and the inner heat insulating pipe, in addition to welding and welding, it is also possible to use screw pipe connection or flange connection, which are appropriate from the connection pipe material, piping specifications, usage environment, etc. It is sufficient to select a suitable method.

By utilizing the system of the present invention configured in this way, even in geothermal formations where the excavation depth is shallow and the bottom temperature is low, or in places where it is difficult to procure cooling water, new steam production and hot spring It is possible to perform geothermal power generation with high efficiency, low cost and space-saving without increasing the pumping amount and without risk of failure due to scale deposition.

(Second Embodiment)

FIG. 6 shows a schematic configuration and functions of an efficient cooling method in the geothermal power generation system according to the second embodiment of the present invention. This is because it is difficult to procure cooling water, and it is difficult to condense and liquefy the medium in the ground, such as areas where the shallow constant temperature layer is heated due to geothermal heat, etc., or there is no aquifer under the ground. In this case, the system configuration example is for efficiently cooling the medium while minimizing the consumption of cooling water on the ground. The contents will be described below with reference to the drawings.

  As shown in FIG. 2, the geothermal power generation system of the present invention includes an adsorption refrigeration machine 15 that uses a medium after power generation as a drive heat source in a closed loop circulation channel in which a power generation medium such as water or pentane circulates, A hermetic cooling tower 16 for driving the refrigerator, a water-cooled heat exchanger 17 for additionally cooling the medium after driving the refrigerator using the cooling water obtained from the refrigerator, and condensation in this heat exchanger The medium pump 18 is configured to pump the liquefied medium into the ground. The upstream side of the power generation system 2 and the medium circulation passage after passing through the medium pumping pump 18 are connected to the coaxial double pipe heat exchanger 1 to form a circulation closed loop type passage. However, this is omitted in the figure.

In this system, the refrigerator is driven using the medium vapor after power generation or the liquefied high-temperature medium as a heat source, taking out the cold while taking heat away from the medium, and further, the cold obtained in this process passes through the refrigerator. By using it for additional cooling of the medium whose temperature has decreased, medium cooling and condensate liquefaction are further promoted, and the medium can be liquefied efficiently on the ground, enabling underground pumping by a liquid feed pump.

In order to drive the refrigerator, a cooling tower that requires cooling water is required. However, if this cooling tower is a closed type rather than an open type, the amount of cooling water replenishment can be reduced, so that it is difficult to procure cooling water. However, the medium can be efficiently cooled.

The present invention is not limited to the above-described embodiment, for example, the use of heat other than power generation, such as greenhouse cultivation using a high-temperature medium obtained by efficiently extracting geothermal heat or winter road heating, or high temperature The present invention can also be applied to the use of cold heat using an adsorption refrigerator that uses a medium. As described above, the above-described embodiment is an exemplification, and what has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same function and effect is any type. Are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ...... Coaxial double pipe heat exchanger with a spiral flow path 2 ... Steam turbine power generator 3 ... Tip pipe with medium dropping nozzle 4 ... Coaxial double pipe heat exchanger outside Pipe 5 ··· Inner insulated pipe support guide
6 ... Coaxial double pipe heat exchanger inner heat insulation pipe 7 ... Medium dropping nozzle 8 ... Nozzle plate 9 ... Downhole contact part 10 of coaxial double pipe heat exchanger ...・ Heat flow promotion plate 11 for underground heat exchange promotion tube ... Heat exchange promotion tube 12 for promoting underground heat absorption 12 ... Heat exchange promotion tube 13 for promoting underground heat release ... Coaxial double tube heat Spacer tube 14 of exchanger ... Liquid level 15 of condensed power generation medium ... Adsorption type refrigerator 16 using medium after power generation as drive heat source ... Sealing cooling tower 17 ... Water cooling of medium after power generation Type heat exchanger 18 ... Medium pressure pump

Claims (8)

A closed-loop circulation type flow in which water, pentane, and other media are heated and raised by absorbing heat from high-temperature geothermal or geothermal fluid, cooled to condensate after use on the ground, and then absorbed again from geothermal or geothermal fluid. Of the underground heat exchangers that make up the road,
A coaxial double pipe composed of an outer tube that exchanges heat with the underground, and an inner heat insulating tube that raises the heated medium to the ground while insulating the heated medium. Furthermore, in the double pipe outer flow path formed in the gap between the inner wall of the outer pipe and the inner heat insulating pipe, in the underground heat exchange promotion part that promotes heat radiation to the ground or heat absorption from the ground A spiral flow path configuration type coaxial heat exchange characterized by comprising a spiral flow path configuration plate that spirals the flow path to promote heat exchange with the ground when the medium flows down in the ground. vessel The spiral flow path constituting plate according to claim 1 is made of a material having high heat conductivity and is fixed to an inner wall of a heat exchange promoting tube inserted in contact with the inner wall of the outer tube, or the heat exchange promoting When the medium flows down the spiral flow path, the heat exchange is facilitated not only on the inner wall of the heat exchange promoting pipe but also on the spiral flow path constituting plate. Method for promoting underground heat exchange using spiral flow path component plates The spiral flow path component plate according to claim 1, which is made of a material having high heat conductivity, and is fixed to an outer wall of the inner heat insulation tube or integrally formed with the inner heat insulation tube. By inserting the heat insulating pipe so as to be in close contact with the inner wall of the outer pipe, when the medium flows down the spiral flow path, heat exchange can be performed not only on the inner wall of the heat exchange promoting pipe but also on the spiral flow path constituting plate. A method for promoting underground heat exchange using a spiral flow path component plate In the spiral flow path according to claim 2 and 3, after adjusting the installation position of the spiral flow path component plate, the installation interval, and the inclination angle of the component plate based on the inner wall temperature distribution of the outer tube, Helical channel configuration type characterized by controlling the heat absorption position and heat absorption amount from geothermal or geothermal fluid, or the heat radiation position and heat radiation amount to the underground low temperature layer or aquifer by fixing or integrally molding Control method of underground heat exchange and heat exchange amount in coaxial heat exchanger In the method for controlling the amount of underground heat exchange according to claim 4, the vertical distance between the plates of the spiral flow path constituting plate is narrowed in a region where the inner wall temperature of the outer pipe is higher than the medium temperature flowing down in the spiral flow path. In a helical flow path configuration type coaxial heat exchanger characterized in that heating of the medium flowing down the helical flow path is promoted by any one of the gentler inclination angle of the plate or a combination thereof, Method for promoting medium underground heating In the method for controlling the amount of underground heat exchange according to claim 4, the vertical distance between the plates of the spiral flow path constituting plate is narrowed in a region where the inner wall temperature of the outer pipe is lower than the medium temperature flowing down in the spiral flow path. In the coaxial heat exchanger having a helical flow path structure, the cooling of the medium flowing down the helical flow path is promoted by any one of these methods, or a combination of these, which makes the inclination angle of the plate gentle. Method for promoting medium underground cooling Both the underground heating promotion method according to claim 5 and the underground cooling promotion method according to claim 6 are arranged in a spiral flow path configuration type coaxial heat exchanger constituting a closed loop circulation flow path, and an outer pipe inner wall By applying according to the temperature distribution of the medium, the medium after power generation is directly pressed into the spiral flow path of the coaxial heat exchanger and condensed and liquefied in a constant temperature layer or a subsurface aquifer in the shallow underground. In addition, the temperature is preheated in the deep underground layer and in the tropical region, and then the temperature is lowered to the inner bottom surface of the outer tube that contacts the bottom of the deep geothermal layer to raise the inside of the inner heat insulating tube. A helical flow path configuration type coaxial heat exchanger characterized in that geothermal power generation is performed in a closed-loop circulation flow path, in which a generator is driven on the ground with medium vapor, and the medium after power generation is again pressed into the ground. Including closed-loop circulation geothermal power generation system A hot medium obtained by the closed-loop circulation channel according to claim 1 or a medium whose temperature is lowered by using the high-temperature medium for power generation or the like is used as a hot water or steam-driven adsorption or absorption refrigerator-driven heat source. And cooling the medium after driving the refrigerator using the cooling water obtained by using the medium as a driving heat source.