WO2022234703A1 - Geothermal heat utilization system, control device, control method, program - Google Patents

Abstract

A geothermal heat utilization system according to the present disclosure comprises: a well; piping having an end on a side extending toward the well; and a heat exchanger provided to the piping. The piping comprises, at the end thereof, a lift pipe connected to a pump capable of pumping groundwater in the well, and a plurality of water injection pipes each provided with a flow control valve.

Description

Geothermal heat utilization system, control device, control method, program

The present disclosure relates to a geothermal heat utilization system, a control device, a control method, and a program.
This application claims priority to Japanese Patent Application No. 2021-78634 filed on May 6, 2021, the content of which is incorporated herein.

In recent years, geothermal heat utilization systems that use groundwater as a heat source or cold heat source have been proposed.

For example, in Patent Document 1, a pumping pipe and a return pipe are inserted into each of two wells, groundwater in one well is pumped up through the pumping pipe, and the groundwater after heat utilization is transferred to the other well. A groundwater heat exchanger has been proposed in which water is injected through a reduction pipe of

Japanese Unexamined Patent Application Publication No. 2011-21804

In the groundwater heat exchanger disclosed in Patent Document 1, in order to keep the temperature of water injected into the wells constant, it is necessary to adjust the amount of water injected according to the load, outside temperature, and the like.
However, in the configuration disclosed in Patent Literature 1, the adjustment of the water injection flow rate is performed only by the pump, and it is desired to make the adjustment of the water injection flow rate even easier.

The present disclosure has been made to solve the above problems, and aims to provide a geothermal heat utilization system, a control device, a control method, and a program that can facilitate flow rate adjustment.

In order to solve the above problems, a geothermal heat utilization system according to the present disclosure includes a well, a pipe having an end on a side extending to the well, and a heat exchanger provided in the pipe, wherein the pipe has, at the end, a pumping pipe connected to a pump capable of pumping groundwater in the well, and a plurality of water injection pipes each having a flow control valve.

A control device according to the present disclosure includes a pump operation control unit that operates a pump provided in one of a pair of wells to pump up groundwater from a pumping pipe provided in one of the wells; provided in each of the plurality of water injection pipes so that the pumped groundwater passes through the heat exchanger and is injected at a predetermined flow rate into the other well through the plurality of water injection pipes provided in the other well. and a valve opening degree control unit that adjusts the opening degree of the flow control valve.

A control method according to the present disclosure operates a pump provided in one of a pair of wells so as to pump up groundwater from a pumping pipe provided in one of the wells, and the groundwater pumped up from the pumping pipe is A flow control valve provided in each of the plurality of water injection pipes so that water is injected at a predetermined flow rate into the other well through the heat exchanger and through the plurality of water injection pipes provided in the other well. Adjust the opening.

A program according to the present disclosure causes a computer to operate a pump provided in the pumping pipe so as to pump groundwater from the pumping pipe provided in one of the wells of a pair of wells, and pumped up from the pumping pipe A flow rate adjustment provided in each of the plurality of water injection pipes so that the groundwater passes through the heat exchanger and is injected into the other well at a predetermined flow rate through the plurality of water injection pipes provided in the other well. Execute the method of adjusting the degree of opening of the valve.

According to the geothermal heat utilization system, control device, control method, and program of the present disclosure, it is possible to easily adjust the flow rate.

1 is a diagram showing a schematic configuration of a geothermal heat utilization system according to an embodiment of the present disclosure; FIG. 1 is a system diagram of a geothermal heat utilization system according to an embodiment of the present disclosure; FIG. 1 is a block diagram of a control device according to an embodiment of the present disclosure; FIG. 4 is a flow chart showing procedures of a control method according to an embodiment of the present disclosure; It is a figure showing an example of hardware constitutions of a computer with which a control device concerning an embodiment of this indication is provided.

Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. The same reference numerals are given to the same or corresponding configurations in all the drawings, and common explanations are omitted.

<Embodiment>
An embodiment of a geothermal heat utilization system according to the present disclosure will be described with reference to FIGS. 1 to 4. FIG.
(Configuration of geothermal heat utilization system)
As shown in FIGS. 1 and 2 , the geothermal heat utilization system 1 mainly includes a well 2 , piping 3 , heat exchanger 4 , and flow control system 7 .
For example, the geothermal heat utilization system 1 may include a pair of wells 2 .

(Composition of the well)
As shown in FIG. 1, a pair of wells 2 extend from above ground OG into aquifer LY.
For example, the pair of wells 2 comprises a first well 2A and a second well 2B.
The underground heat utilization system 1 draws up groundwater from one of the first well 2A and the second well 2B, and after heat exchange with the heat exchanger 4, Groundwater after heat exchange is injected into the other. In other words, the geothermal heat utilization system 1 has two functions, one for pumping up groundwater from the first well 2A and pouring it into the second well 2B, and the other for pumping up groundwater from the second well 2B and pouring it into the first well 2A. It has a driving mode.
Here, in the following description, of the first well 2A and the second well 2B, the side from which groundwater is pumped up is referred to as a pumping well 21, and of the first well 2A and the second well 2B, the side to which groundwater is injected is water injection. It is called well 22 . That is, the first well 2A and the second well 2B may function as pumping wells 21 and may function as water injection wells 22, respectively.
However, in order to simplify the explanation below, the case where the first well 2A is the pumping well 21, the second well 2B is the water injection well 22, and the heat exchanger 4 performs heat exchange will be mainly explained.

Each well 2 comprises a casing 2a embedded in a borehole HOL drilled from the surface OG to the aquifer LY underground.
The casing 2a has a tubular shape extending in the vertical direction.

Each well 2 has an opening 2c at the top.
For example, opening 2c may be an opening in the top of casing 2a.

The casing 2a has a strainer 2b made up of, for example, a plurality of slits.
The strainer 2b allows the well 2 to take groundwater from the aquifer LY into the casing 2a and return the groundwater from the casing 2a to the aquifer LY.
For example, the upper opening of the casing 2a may be provided with a well cover (not shown) that closes the opening.

(Piping configuration)
As shown in FIGS. 1 and 2, the pipe 3 has an end on the side extending to the well 2 .
The piping 3 has a water pumping pipe 71 and a plurality of water injection pipes 75 at its end.
For example, the pipe 3 may include a pumping pipe 71 and a plurality of water injection pipes 75 at the ends of the pair of wells 2 extending to each well 2 .
For example, in this embodiment, the pipe 3 includes a pumping pipe 71 and a plurality of water injection pipes 75 at both ends of the pair of wells 2 . In other words, the pipe 3 has a pumping pipe 71 and a plurality of water injection pipes 75 at the end 3a on the side of the first well 2A and the end 3b on the side of the second well 2B.
The pumping pipe 71 and the plurality of water injection pipes 75 are branched from the ends 3a and 3b of the pipe 3, respectively.

The pumping pipe 71 extends into the well 2 from the ground OG.
Both ends of the pumping pipe 71 may be immersed in the groundwater of the well 2 .
The pumping pipe 71 pumps groundwater from the well 2 (pumping well 21 ) when the well 2 on the side where the pumping pipe 71 is provided functions as the pumping well 21 .

A pump 72 is provided in the pumping pipe 71 .
A pump 72 pumps water from the well 2 to the pipe 3 .
For example, the pump 72 pumps water from the well 2 to the pipe 3 when the well 2 functions as the pumping well 21 .
For example, pump 72 may pump groundwater in well 2 into pipe 3 .
For example, the pump 72 may be provided in the water discharge pipe 71 and immersed in the ground water in each well 2 .
For example, the pump 72 may be able to change its output by inverter control.

A check valve 73 is provided in the pumping pipe 71 .
The check valve 73 is provided closer to the heat exchanger 4 than the pump 72 in the pumping pipe 71 .
The check valve 73 is provided closer to the pump 72 than the connecting portion between the pumping pipe 71 and the ends 3 a and 3 b of the pipe 3 .
The check valve 73 prevents part of the injected groundwater from flowing back to the pump 72 when water is injected from the pipe 3 through the water injection pipe 75 in the well 2 on the side where the check valve 73 is provided.

At ends 3a and 3b of the pipe 3 on the side of each well 2 (the first well 2A and the second well 2B), a plurality of water injection pipes 75 extend into the well 2 from the ground OG.
Both ends of each water injection pipe 75 may be immersed in the groundwater of the well 2 .
In this embodiment, two water injection pipes 75 are provided, for example.
Three or more water injection pipes 75 may be provided.
The multiple water injection pipes 75 inject groundwater into the well 2 (water injection well 22 ) when the well 2 provided with the multiple water injection pipes 75 functions as the water injection well 22 .

The plurality of water injection pipes 75 may have different pipe diameters.
In this embodiment, the multiple water injection pipes 75 include a small diameter water injection pipe 75A and a large diameter water injection pipe 75B.
The small-diameter water injection pipe 75A has a smaller pipe diameter than the large-diameter water injection pipe 75B.
The large diameter water injection pipe 75B has a larger pipe diameter than the small diameter water injection pipe 75A.
The small-diameter water injection pipe 75A and the large-diameter water injection pipe 75B may each have a smaller diameter than the water pumping pipe 71 .
The small-diameter water injection pipe 75A and the large-diameter water injection pipe 75B are arranged so that the sum of the flow channel cross-sectional area of the small-diameter water injection pipe 75A and the flow channel cross-sectional area of the large-diameter water injection pipe 75B is equal to or greater than the flow channel cross-sectional area of the pumping pipe 71. can be

A flow control valve 77 is provided in each of the plurality of water injection pipes 75 .
A small-diameter flow control valve 77A is provided as a flow control valve 77 on the small-diameter water injection pipe 75A.
A large-diameter flow control valve 77B is provided as the flow control valve 77 on the large-diameter injection pipe 75B.
The small-diameter flow control valve 77A has a smaller diameter than the large-diameter flow control valve 77B.
The small-diameter flow control valve 77A has a diameter that matches the pipe diameter of the small-diameter water injection pipe 75A.
The large-diameter flow control valve 77B has a diameter that matches the diameter of the large-diameter water injection pipe 75B.

The flow control valve 77 adjusts the flow rate of groundwater flowing through the water injection pipe 75 .
The flow control valve 77 adjusts the flow rate of groundwater flowing through the water injection pipe 75 provided in the water injection well 22 when the well 2 functions as the water injection well 22 .
By adjusting the degree of opening of the flow control valve 77, the flow rate of groundwater in the water injection pipe 75 provided with the flow control valve 77 can be adjusted.
When stopping the operation of the geothermal heat utilization system 1 , the flow rate control valve 77 may stop the operation of the pump 72 after the flow rate control valve 77 is fully closed. Thereby, the geothermal heat utilization system 1 can stop the operation while the groundwater in the pipe 3 is maintained in a pressurized state.

A plurality of flow control valves 77 provided in a plurality of water injection pipes 75 can independently adjust the valve opening degree.
It is also possible to close the flow control valve 77 of some (one) water injection pipes 75 among the plurality of water injection pipes 75 and pour water into the well 2 on the water injection side only from the other water injection pipe 75 .

As shown in FIG. 2, the pipe 3 includes check valves 35a to 35d between the heat exchanger 4 and the pair of wells 2. As shown in FIG.
The check valves 35a to 35d allow the groundwater to flow in the same direction to the heat exchanger 4 regardless of whether the groundwater is pumped up from the first well 2A or the second well 2B. so as to control the flow of groundwater in the pipe 3 .

For example, when groundwater is pumped up from the first well 2A, the groundwater in the pipe 3 flows from the first well 2A through the check valve 35a, the heat exchanger 4, and the check valve 35b in order, and then to the second well 2B. Water is injected. At this time, since the pressure in the pipe 3 is higher on the upstream side (first well 2A side) than the downstream side of the heat exchanger 4, water does not flow through the check valves 35c and 35d.
Similarly, when pumping up from the second well 2B, the groundwater in the pipe 3 passes through the check valve 35c, the heat exchanger 4, and the check valve 35d in order from the second well 2B and is injected into the first well 2A. be done. At this time as well, water does not flow through the check valves 35a and 35b because the pressure in the pipe 3 is higher on the upstream side (second well 2B side) of the heat exchanger 4 than on the downstream side.

(Configuration of heat exchanger)
The heat exchanger 4 exchanges heat between the groundwater in the pipe 3 and the medium on the load equipment 100 side.
For example, the heat exchanger 4 exchanges heat between the groundwater pumped up from the well 2 and flowing through the piping 3 and the medium on the load equipment 100 side. After the heat exchange, the groundwater flows from the heat exchanger 4 through the piping 3 and is injected into the well 2 .
For example, the heat exchanger 4 may be provided in the middle of the pipe 3 on the ground OG.

When the water that has passed through the heat exchanger 4 is hot water, the geothermal heat utilization system 1 performs hot water heat storage by injecting hot water into the well 2 .
When the water that has passed through the heat exchanger 4 is cold water, the geothermal heat utilization system 1 stores cold water heat by injecting hot water into the well 2 .
Here, "hot water" means water with a temperature higher than the initial temperature of the groundwater in the aquifer, and "cold water" means water with a temperature lower than the initial temperature of the groundwater in the aquifer. That is.
For example, the initial ground temperature of groundwater in an aquifer is 18°C.

(Configuration of flow rate adjustment system)
The flow control system 7 includes a pump controller 74 , the flow control valve 77 and a controller 80 . The flow control system 7 adjusts the water injection temperature of the water injection well 22 by adjusting the flow rate of the groundwater that is injected into the water injection well 22 .

Pump controller 74 controls the operation of pump 72 .
For example, a pump controller 74 may be provided associated with each well 2 pump 72 .
For example, the pump controller 74 has an inverter circuit (not shown) and implements inverter control of the pump 72 .
The pump controller 74 adjusts the rotation speed of the pump 72 by varying the operating frequency of the inverter control by the inverter circuit under the control of the control device 80, which will be described later.
The pump controller 74 adjusts the rotation speed of the pump 72 by varying the operating frequency of the inverter control by the inverter circuit, and adjusts the flow rate of the groundwater injected into the injection well 22 from the pipe 3 via the heat exchanger 4 .
Hereinafter, the inverter-controlled operating frequency of the pump 72 is also referred to as "the operating frequency of the pump 72".

(Configuration of control device)
The controller 80 adjusts the flow rate of groundwater injected into the injection well 22 .
The control device 80 adjusts the operating frequency of the pump 72 and the opening degree of the flow control valve 77 so that the temperature of the groundwater injected into the injection well 22 is constant.
The controller 80 adjusts only the operating frequency of the pump 72 in a region where the operating frequency of the pump 72 is equal to or higher than a predetermined minimum frequency, thereby adjusting the flow rate of groundwater injected into the water injection well 22 .
For example, controller 80 may be controllably connected to each pump controller 74 .

For example, controller 80 may be controllably connected to each flow control valve 77 .
For example, when the operating frequency of the pump 72 drops to the lowest frequency, the control device 80 adjusts the flow rate of groundwater injected into the injection well 22 by adjusting the opening degree of the flow control valve 77 .
When the operating frequency of the pump 72 drops to the lowest frequency, the control device 80 reduces the flow rate of the groundwater injected into the injection well 22 by narrowing (reducing) the opening degree of the flow control valve 77 .
For example, the controller 80 reduces the operating frequency of the pump 72 to the lowest frequency and adjusts the flow rate of the groundwater injected into the water injection well 22 by adjusting the opening of the flow control valve 77. may be kept at the lowest frequency.

For example, when the operating frequency of the pump 72 is lowered to the lowest frequency and the flow rate of the groundwater to the well 2 on the water injection side is smaller than a predetermined flow rate setting reference value, the control device 80 controls the two water injection pipes. 75, only the flow control valve 77 provided in the small-diameter water injection pipe 75A may be opened.

As shown in FIG. 3 , the control device 80 includes a pump operation control section 81 and a valve opening degree control section 82 .

The pump operation control unit 81 adjusts the rotation speed of the pump 72 by varying the operating frequency of the inverter control by the inverter circuit of the pump controller 74 .
The pump operation control unit 81 adjusts the operating frequency of the pump 72 that pumps up groundwater from the pumping well 21 according to the temperature of the groundwater that is injected into the water injection well 22 .
The pump operation control unit 81 adjusts the flow rate of groundwater injected from the pipe 3 into the injection well 22 by varying the operating frequency of the pump 72 based on a map or the like stored in advance.
For example, when the load facility 100 performs the cooling operation and the hot water heat storage is performed in the water injection well 22, the pump operation control unit 81 determines the difference between the actual injection temperature of the groundwater injected into the water injection well 22 from the pipe 3 and the set temperature. The operating frequency of pump 72 is controlled based on the difference.
For example, when the load facility 100 performs heating operation and cold water heat storage is performed in the water injection well 22, the pump operation control unit 81 determines the difference between the actual injection temperature of the groundwater injected into the water injection well 22 from the pipe 3 and the set temperature. The operating frequency of pump 72 is controlled based on the difference.
The pump operation control unit 81 controls the pump controller 74 so as to adjust the operating frequency (output) of the pump 72 according to the required injection water temperature based on a map or the like stored in advance.
The pump operation control unit 81 stores, for example, the lower limit of the operating frequency at which the pump 72 can stably operate as the lowest frequency. The pump operation control unit 81 controls the pump controller 74 so as to adjust the operation of the pump 72 in a frequency range equal to or higher than a preset minimum frequency.

The valve opening degree control unit 82 adjusts the flow rate of groundwater in the pipe 3 by opening and closing the flow control valve 77 .
The valve opening degree control unit 82 adjusts the flow rate of the groundwater in the pipe 3 by adjusting the opening degree of the flow rate adjustment valve 77 .
The valve opening control unit 82 adjusts the opening of the flow control valve 77 when the operating frequency of the pump 72 has decreased to the lowest frequency.
The valve opening degree control unit 82 adjusts the opening degree of the flow control valve 77 according to the temperature of the groundwater injected into the water injection well 22 when the operating frequency of the pump 72 becomes the lowest frequency.

In this embodiment, when the operating frequency of the pump 72 is lowered to the lowest frequency and the flow rate of the groundwater to the well 2 on the water injection side is smaller than the predetermined flow rate setting reference value Of the two water injection pipes 75, only the small diameter flow control valve 77A provided in the small diameter water injection pipe 75A is opened, and water is injected into the well 2 on the water injection side only from the small diameter water injection pipe 75A.
In this embodiment, when the operating frequency of the pump 72 is lowered to the lowest frequency and the flow rate of the groundwater to the well 2 on the water injection side is smaller than the predetermined flow rate setting reference value , the opening adjustment may be performed only by the small-diameter water injection pipe 75A.
In this embodiment, when the operating frequency of the pump 72 is lowered to the lowest frequency and the flow rate of the groundwater to the well 2 on the water injection side is greater than the predetermined flow rate setting reference value, the valve opening degree control section 82 , both the small diameter flow control valve 77A provided in the small diameter water injection pipe 75A and the large diameter flow control valve 77B provided in the large diameter water injection pipe 75B are opened, and both the small diameter water injection pipe 75A and the large diameter water injection pipe 75B are opened. It is also possible to pour water into the well 2 on the water-injection side.
In this embodiment, when the operating frequency of the pump 72 is lowered to the lowest frequency and the flow rate of the groundwater to the well 2 on the water injection side is greater than the predetermined flow rate setting reference value, the valve opening degree control section 82 Alternatively, the opening may be adjusted only by the large-diameter flow control valve 77B provided in the large-diameter water injection pipe 75B.

The operation of the control device 80 of this embodiment will be described.
The operation of the control device 80 corresponds to an embodiment of the control method.
The control device 80 implements each step shown in FIG.

First, when the load equipment 100 side is operating in the cooling mode or the heating mode, the pump operation control unit 81 operates the pump 72 to control the pumping pipe of one pumping well 21 of the pair of wells 2. Pump up groundwater from 71 (ST01: step of operating the pump). Groundwater pumped up from the pumping well 21 is thereby sent to the heat exchanger 4 through the pipe 3 . In the heat exchanger 4, the groundwater in the pipe 3 exchanges heat with the medium on the load facility 100 side. Groundwater that has passed through the heat exchanger 4 is injected from the water injection pipe 75 into the other water injection well 22 . At this time, on the water injection well 22 side, the geothermal heat utilization system 1 injects water through all of the plurality of water injection pipes 75 (the small diameter water injection pipe 75A and the large diameter water injection pipe 75B).
At the initial stage when the pump 72 is started, the valve opening degree control unit 82 may open only the small diameter flow rate adjustment valve 77A and inject water into the injection well 22 only from the small diameter water injection pipe 75A. After that, the valve opening degree control section 82 may open the small diameter flow control valve 77A as the operating frequency of the pump 72 increases to increase the water injection flow rate in the small diameter water injection pipe 75A. Further, the valve opening degree control unit 82 further opens the large-diameter flow control valve 77B in a state where the operating frequency of the pump 72 has increased to some extent, and the small-diameter water injection pipe 75A and the large-diameter water injection pipe 75B flow water into the water injection well 22. You may make it pour water. Thereafter, as the operating frequency of the pump 72 increases, the valve opening control unit 82 may further open the large-diameter flow control valve 77B to increase the water injection flow rate in the large-diameter water injection pipe 75B. .

When the load equipment 100 side is operating in the cooling mode or the heating mode, the pump operation control unit 81 controls the pumping well 21 according to the set temperature of the groundwater injected into the injection well 22 via the heat exchanger 4. The operating frequency of the inverter control of the pump 72 that feeds the groundwater from the well 22 is adjusted (ST02: step of adjusting the operating frequency of the pump). As a result, the flow rate of water injected from the pumped well 21 to the water injection well 22 by the pump 72 is adjusted.

Following the execution of ST02, the pump operation control unit 81 determines whether or not the operating frequency of the inverter control of the pump 72 has decreased to the lowest frequency (ST03: Whether or not the operating frequency of the pump has decreased to the lowest frequency). a step of determining whether or not).

As a result of the determination in ST03, if the inverter-controlled operating frequency of the pump 72 has not decreased to the lowest frequency, the process returns to ST02, and the pump operation control section 81 controls the water injection flow rate from the pumping well 21 to the water injection well 22 by the pump 72. continue to adjust
As a result of the determination in ST03, if the operating frequency of the inverter control of the pump 72 has decreased to the lowest frequency, the valve opening degree control unit 82 increases the diameter The opening degree of the flow control valve 77B is adjusted in the closing direction (ST04: step of adjusting the opening degree of the large-diameter flow control valve). The valve opening degree control unit 82 adjusts the flow rate of water injected into the water injection well 22 by adjusting the opening degree of the large-diameter flow rate control valve 77B. At this time, the pump operation control unit 81 maintains the inverter control operation frequency of the pump 72 at the lowest frequency. In other words, by closing the large-diameter flow control valve 77B while the operating frequency of the inverter control of the pump 72 is the lowest frequency, the control device 80 further reduces the flow rate of the groundwater injected into the injection well 22.

Following the execution of ST04, the valve opening degree control unit 82 determines whether or not the opening degree of the large diameter flow control valve 77B is fully closed (ST05: the opening degree of the large diameter flow control valve is fully closed). step of determining whether or not).
As a result of the determination in ST05, if the opening degree of the large-diameter flow control valve 77B is not fully closed, the process returns to ST04, and the valve opening degree control section 82 continues the processing.
If the opening degree of the large-diameter flow control valve 77B is fully closed as a result of the determination in ST05, the flow rate of the groundwater injected into the well 2 is smaller than the flow rate setting reference value. , through only the small-diameter water injection pipe 75A. In this case, the valve opening degree control unit 82 adjusts the opening degree of the small diameter flow rate control valve 77A in the closing direction according to the set temperature of the groundwater injected into the water injection well 22 (ST06: opening degree of the small diameter flow rate regulation valve ). The valve opening degree control unit 82 adjusts the flow rate of water injected into the water injection well 22 by adjusting the opening degree of the small-diameter flow rate control valve 77A. Even at this time, the pump operation control unit 81 maintains the inverter control operation frequency of the pump 72 at the lowest frequency. That is, in a state where the operating frequency of the inverter control of the pump 72 is the lowest frequency, the valve opening degree control unit 82 closes the small diameter flow control valve 77A while injecting water into the water injection well 22 only through the small diameter water injection pipe 75A. go. Thereby, the control device 80 can further reduce the flow rate of the groundwater injected into the injection well 22 .

When stopping the operation of the geothermal heat utilization system 1, the valve opening degree control unit 82 fully closes the small-diameter flow control valve 77A and the large-diameter flow control valve 77B, and then the pump operation control unit 81 The operation of the pump 72 is stopped. Thereby, the geothermal heat utilization system 1 can stop the operation while the groundwater in the pipe 3 is maintained in a pressurized state. By keeping the groundwater in the pipe 3 in a pressurized state (positive pressure), entry of foreign matter and oxygen into the pipe 3 from the outside can be suppressed, and corrosion of the pipe 3 can be suppressed.

(Action and effect)
According to this embodiment, the geothermal heat utilization system 1 can send groundwater pumped up from the well 2 by the pump 72 to the heat exchanger 4 through the pumping pipe 71 and the pipe 3 . On the other hand, in the geothermal heat utilization system 1, when the groundwater that has passed through the heat exchanger 4 is injected into the well 2 through the pipe 3 and the water injection pipe 75, the opening of the flow rate adjustment valve 77 provided in the water injection pipe 75 is By adjusting, the flow rate of the groundwater injected into the well 2 can be adjusted. At this time, a plurality of water injection pipes 75 are provided. A flow control valve 77 is provided for each of the plurality of water injection pipes 75 . Therefore, by adjusting the opening degree of the flow control valve 77 in each of the plurality of water injection pipes 75, the geothermal heat utilization system 1 can more finely adjust the flow rate of the groundwater injected into the well 2. can be done. For example, the geothermal heat utilization system 1 opens the flow control valves 77 of some of the plurality of water injection pipes 75 and closes the flow control valves 77 of the other water injection pipes 75, and the groundwater injected into the well 2 It is also possible to adjust the flow rate of Therefore, the geothermal heat utilization system 1 can facilitate flow rate adjustment.
In addition, since the pump 72 is provided in the pumping pipe 71, and the flow rate adjustment valve 77 is provided in the water injection pipe 75, the user can handle the pumping pipe 71 side, Or it becomes easy to specify the cause of which side of the water injection pipe 75 is causing the trouble. In addition, since the user can replace the pump 72 alone and the flow control valve 77 alone, maintenance can be performed easily and at low cost.

Further, according to one example of the present embodiment, the pipe 3 includes a pumping pipe 71 and a plurality of water injection pipes 75 at the ends of the pair of wells 2 extending to each of the wells 2 .
As a result, a plurality of water injection pipes 75 are provided at the ends 3a and 3b extending to each well 2, respectively, so that the geothermal heat utilization system 1 can easily adjust the flow rate of groundwater injected into each well 2. can do.

Further, according to one example of the present embodiment, when stopping the operation of the geothermal heat utilization system 1, the geothermal heat utilization system 1 stops the operation of the pump 72 after fully closing the flow rate adjustment valve 77. Thus, the operation can be stopped while the groundwater in the pipe 3 is maintained in a pressurized state. In this way, the geothermal heat utilization system 1 keeps the groundwater in the pipe 3 in a pressurized state (positive pressure), thereby suppressing the entry of foreign matter and oxygen into the pipe 3 from the outside and preventing corrosion of the pipe 3. can be suppressed.

Further, according to one example of this embodiment, the geothermal heat utilization system 1 further includes a valve opening degree control section 82 that adjusts the opening degree of the flow rate adjustment valve 77 according to the water injection flow rate to the well 2 .
As a result, the geothermal heat utilization system 1 can easily adjust the water injection temperature by adjusting the opening degree of the flow rate adjustment valve 77 with the valve opening degree control unit 82 according to the water injection flow rate to the well 2. .

Further, according to one example of the present embodiment, the valve opening degree control unit 82 is provided in some of the plurality of water injection pipes 75 when the flow rate of the groundwater injected into the well 2 is smaller than the flow rate setting reference value. Open only the flow control valve 77 that is set.
Thus, by providing a plurality of water injection pipes 75, the pipe diameter of each water injection pipe 75 and the diameter of the flow control valve 77 provided in each water injection pipe 75 can be reduced. Therefore, in the geothermal heat utilization system 1, when the flow rate of groundwater injected into the well 2 is small, by opening only the flow rate adjustment valves 77 of some of the plurality of water injection pipes 75, It is possible to more finely adjust the flow rate of groundwater in a small flow area.

Further, according to one example of the present embodiment, the plurality of water injection pipes 75 have different pipe diameters.
As a result, for example, when the flow rate of groundwater injected into the well 2 is small, the geothermal heat utilization system 1 adjusts the flow rate of the groundwater injected into the well 2 only with the small diameter flow control valve 77A of the small diameter water injection pipe 75A. It can be performed. Thereby, the geothermal heat utilization system 1 can more finely adjust the flow rate of the groundwater in the low flow rate region.

Further, according to one example of the present embodiment, the control device 80 includes a pump operation control section 81 and a valve opening degree control section 82 .
Accordingly, by operating the pump 72 with the pump operation control unit 81 , the control device 80 can pump up groundwater from the pumping pipe 71 provided in one of the pair of wells 2 . Groundwater pumped up from the pumping pipe 71 passes through the heat exchanger 4 and is injected into the other well 2 from a plurality of water injection pipes 75 . By adjusting the opening degree of the flow control valve 77 provided in each of the plurality of water injection pipes 75 by the valve opening degree control unit 82, the control device 80 adjusts the flow rate of the groundwater injected into the other well 2. easier to do.

<Modification>
In the above-described embodiment, the program for realizing various functions of the control device 80 is recorded in a computer-readable recording medium, and the program recorded in this recording medium is read by a computer system such as a microcomputer. , to perform various processes. Here, various processes of the CPU of the computer system are stored in a computer-readable recording medium in the form of programs, and the above various processes are performed by reading and executing the programs by the computer. Computer-readable recording media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like. Alternatively, the computer program may be distributed to a computer via a communication line, and the computer receiving the distribution may execute the program.

An example of the hardware configuration of the computer 190 that executes programs for realizing various functions of the control device 80 in the above-described embodiment will be described.

As shown in FIG. 5, a computer 190 provided in the control device 80 includes a processor 195, a memory 196, a storage/playback device 197, an Input Output Interface (hereinafter referred to as "IO I/F") 198, and communication Interface (hereinafter referred to as “communication I/F”) 199 .

For example, processor 195 may be a CPU.
For example, the memory 196 may be a medium such as a Random Access Memory (hereinafter referred to as “RAM”) that temporarily stores data used by programs executed by the control device 80 .
For example, the storage/playback device 197 may be a device for storing data or the like in external media such as a CD-ROM, DVD, or flash memory, or playing back data or the like from the external media.
For example, the IO I/F 198 may be an interface for inputting/outputting information between the control device 80 and another device.
For example, the communication I/F 199 may be an interface that performs communication between the control device 80 and another device via a communication line such as the Internet or a dedicated communication line.

<Other embodiments>
Although the embodiment of the present disclosure has been described above, the embodiment is shown as an example and is not intended to limit the scope of the present disclosure. This embodiment can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the gist of the present disclosure. This embodiment and its modifications are intended to be included in the scope and equivalents of the present disclosure as well as included in the scope and gist of the present disclosure.

<Appendix>
The geothermal heat utilization system 1, the control device 80, the control method, and the program described in the embodiment are grasped as follows, for example.

(1) A geothermal heat utilization system 1 according to a first aspect includes a well 2, a pipe 3 having an end on the side extending to the well 2, and a heat exchanger 4 provided in the pipe 3. , the pipe 3 has, at the end, a pumping pipe 71 connected to a pump 72 capable of pumping groundwater in the well 2, and a plurality of water injection pipes 75 each having a flow control valve 77.

This geothermal heat utilization system 1 can send groundwater pumped from a well 2 by a pump 72 to a heat exchanger 4 through a pumping pipe 71 and a pipe 3 . On the other hand, in the geothermal heat utilization system 1, when the groundwater that has passed through the heat exchanger 4 is injected into the well 2 through the pipe 3 and the water injection pipe 75, the opening of the flow rate adjustment valve 77 provided in the water injection pipe 75 is By adjusting, the flow rate of the groundwater injected into the well 2 can be adjusted. At this time, a plurality of water injection pipes 75 are provided. A flow control valve 77 is provided for each of the plurality of water injection pipes 75 . Therefore, by adjusting the opening degree of the flow control valve 77 in each of the plurality of water injection pipes 75, the geothermal heat utilization system 1 can more finely adjust the flow rate of the groundwater injected into the well 2. can be done. For example, the geothermal heat utilization system 1 opens the flow control valves 77 of some of the plurality of water injection pipes 75 and closes the flow control valves 77 of the other water injection pipes 75, and the groundwater injected into the well 2 It is also possible to adjust the flow rate of Therefore, the geothermal heat utilization system 1 can facilitate flow rate adjustment.

(2) The geothermal heat utilization system 1 according to the second aspect is the geothermal heat utilization system 1 of (1), which includes a pair of the wells 2, and the pipes 3 extend to the respective wells 2. The end portions 3a and 3b may be provided with the water pumping pipe 71 and a plurality of the water injection pipes 75. As shown in FIG.

As a result, a plurality of water injection pipes 75 are provided at the ends 3a and 3b of the pipe 3 extending to each well 2, so that the geothermal heat utilization system 1 can control the flow rate of the groundwater injected into each well 2. You can make adjustments easier.

(3) A geothermal heat utilization system 1 according to a third aspect is the geothermal heat utilization system 1 of (1) or (2), wherein the flow control valve 77 increases the pressure in the pipe 3. It may be capable of being held under pressure.

As a result, when the operation of the geothermal heat utilization system 1 is to be stopped, the geothermal heat utilization system 1 fully closes the flow control valve 77 and then stops the operation of the pump 72 so that the inside of the pipe 3 is Operation can be stopped while the groundwater remains pressurized. In this way, the geothermal heat utilization system 1 keeps the groundwater in the pipe 3 in a pressurized state (positive pressure), thereby suppressing the entry of foreign matter and oxygen into the pipe 3 from the outside and preventing corrosion of the pipe 3. can be suppressed.

(4) A geothermal heat utilization system 1 according to a fourth aspect is the geothermal heat utilization system 1 according to any one of (1) to (3), wherein the A valve opening degree control unit 82 that adjusts the opening degree of the flow rate adjustment valve 77 may be further provided.

As a result, the geothermal heat utilization system 1 can easily adjust the water injection temperature by adjusting the opening degree of the flow rate adjustment valve 77 with the valve opening degree control unit 82 according to the water injection flow rate to the well 2. .

(5) A geothermal heat utilization system 1 according to a fifth aspect is the geothermal heat utilization system 1 according to any one of (1) to (4), wherein the valve opening degree control unit 82 controls the well 2, only the flow control valve 77 provided in a part of the plurality of water injection pipes 75 may be opened.

Accordingly, by providing a plurality of water injection pipes 75, the pipe diameter of each water injection pipe 75 and the diameter of the flow control valve 77 provided in each water injection pipe 75 can be reduced. Therefore, in the geothermal heat utilization system 1, when the flow rate of groundwater injected into the well 2 is small, by opening only the flow rate adjustment valves 77 of some of the plurality of water injection pipes 75, It is possible to more finely adjust the flow rate of groundwater in a small flow area.

(6) A geothermal heat utilization system 1 according to a sixth aspect is the geothermal heat utilization system 1 according to any one of (1) to (5), wherein the plurality of water injection pipes 75 have a pipe diameter of may differ from each other.

As a result, for example, when the flow rate of groundwater injected into the well 2 is small, the geothermal heat utilization system 1 adjusts the flow rate of the groundwater injected into the well 2 only with the flow rate adjustment valve 77 of the small-diameter water injection pipe 75. It can be performed. Thereby, the geothermal heat utilization system 1 can more finely adjust the flow rate of the groundwater in the low flow rate region.

(7) The control device 80 according to the seventh aspect operates the pump 72 provided in the pumping pipe 71 so as to pump up groundwater from the pumping pipe 71 provided in one of the pair of wells 2. The groundwater pumped up from the pump operation control unit 81 and the pumping pipe 71 passes through the heat exchanger 4 and passes through the plurality of water injection pipes 75 provided in the other well 2 to the other well 2 at a predetermined flow rate. and a valve opening degree control unit 82 that adjusts the opening degree of a flow rate adjustment valve 77 provided in each of the plurality of water injection pipes 75 so that water is injected at .

Accordingly, by operating the pump 72 with the pump operation control unit 81 , the control device 80 can pump up groundwater from the pumping pipe 71 provided in one of the pair of wells 2 . Groundwater pumped up from the pumping pipe 71 passes through the heat exchanger 4 and is injected into the other well 2 from a plurality of water injection pipes 75 . By adjusting the opening degree of the flow control valve 77 provided in each of the plurality of water injection pipes 75 by the valve opening degree control unit 82, the control device 80 adjusts the flow rate of the groundwater injected into the other well 2. easier to do.

(8) The control method according to the eighth aspect operates the pump 72 provided in the pumping pipe 71 so as to pump groundwater from the pumping pipe 71 provided in one of the pair of wells 2 . , so that the groundwater pumped up from the water pumping pipe 71 passes through the heat exchanger 4 and is injected into the other well 2 at a predetermined flow rate through a plurality of water injection pipes 75 provided in the other well 2 The opening degree of the flow control valve 77 provided for each of the water injection pipes 75 is adjusted.

Accordingly, the control method can pump up groundwater from the pumping pipe 71 provided in one of the pair of wells 2 by operating the pump 72 . Groundwater pumped up from the pumping pipe 71 passes through the heat exchanger 4 and is injected into the other well 2 from a plurality of water injection pipes 75 . By adjusting the opening degree of the flow control valve 77 provided in each of the plurality of water injection pipes 75, the control method can easily adjust the flow rate of the groundwater injected into the other well 2.

(9) The program according to the ninth aspect instructs the computer 190 to pump up groundwater from the pump 71 provided in one of the pair of wells 2 , the pump 72 provided in the pump 71 . is operated, and the groundwater pumped up from the pumping pipe 71 passes through the heat exchanger 4 and is injected into the other well 2 at a predetermined flow rate through a plurality of water injection pipes 75 provided in the other well 2. Thus, the method of adjusting the opening degree of the flow control valve 77 provided in each of the plurality of water injection pipes 75 is executed.

Thereby, the computer 190 can pump up groundwater from the pumping pipe 71 provided in one of the pair of wells 2 by operating the pump 72 . Groundwater pumped up from the pumping pipe 71 passes through the heat exchanger 4 and is injected into the other well 2 from a plurality of water injection pipes 75 . By adjusting the opening degree of the flow control valve 77 provided in each of the plurality of water injection pipes 75, the flow rate of the groundwater injected into the other well 2 can be easily adjusted.

1 Geothermal heat utilization system 2 Well 2A First well 2B Second well 2a Casing 2b Strainer 2c Opening 3 Piping 3a End 3b End 4 Heat exchanger 7 Flow control system 21 pumping well 22 water injection wells 35a to 35d check valve 71 pumping pipe 72 pump 73 check valve 74 pump controller 75 water injection pipe 75A small diameter water injection pipe 75B large diameter water injection pipe 77 flow rate adjustment Valve 77A Small-diameter flow control valve 77B Large-diameter flow control valve 80 Control device 81 Pump operation control unit 82 Valve opening control unit 100 Load equipment 190 Computer 195 Processor 196 Memory 197 Storage/reproduction device 198 IO I/F
199...Communication I/F
HOL Boring hole LY Aquifer OG Aboveground ST01 Step ST02 for operating the pump Step ST03 for adjusting the operating frequency of the pump Step ST04 for determining whether the operating frequency of the pump has decreased to the lowest frequency or not ST04 Step ST05 of adjusting the degree of opening of the large-diameter flow control valve Step ST06 of determining whether or not the degree of opening of the large-diameter flow control valve is fully closed Step ST06 of adjusting the degree of opening of the small-diameter flow control valve

Claims (9)

1. a well;
   a pipe having an end on a side extending to the well;
   a heat exchanger provided in the pipe, wherein the pipe has, at the end,
   a pumping pipe connected to a pump capable of pumping groundwater in the well;
   A plurality of water injection pipes each equipped with a flow control valve,
   geothermal heat utilization system.
2. A pair of said wells,
   At the end of the pipe extending to each of the wells,
   the pumping pipe;
   a plurality of said water injection pipes;
   The geothermal heat utilization system according to claim 1, comprising:
3. The geothermal heat utilization system according to claim 1 or 2, wherein the flow rate control valve can keep the pressure in the pipe in a pressurized state.
4. The geothermal heat utilization system according to any one of claims 1 to 3, further comprising a valve opening degree control unit that adjusts the degree of opening of the flow control valve according to the water injection flow rate into the well.
5. When the flow rate of the groundwater injected into the well is smaller than a flow rate setting reference value, the valve opening degree control unit opens only the flow rate adjustment valve provided in a part of the plurality of water injection pipes. The geothermal heat utilization system according to claim 4.
6. The geothermal heat utilization system according to any one of claims 1 to 5, wherein the plurality of water injection pipes have different pipe diameters.
7. a pump operation control unit that operates a pump provided in one of a pair of wells to pump up groundwater from the pump provided in one of the wells;
   of the plurality of water injection pipes so that the groundwater pumped up from the pumping pipe passes through a heat exchanger and is injected into the other well at a predetermined flow rate through the plurality of water injection pipes provided in the other well. A control device comprising a valve opening degree control section that adjusts the degree of opening of each flow control valve.
8. Operating a pump provided in the pumping pipe so as to pump groundwater from the pumping pipe provided in one of the wells of a pair of wells;
   of the plurality of water injection pipes so that the groundwater pumped up from the pumping pipe passes through a heat exchanger and is injected into the other well at a predetermined flow rate through the plurality of water injection pipes provided in the other well. A control method that adjusts the opening of the flow control valve provided for each.
9. to the computer,
   Operating a pump provided in the pumping pipe so as to pump groundwater from the pumping pipe provided in one of the wells of a pair of wells;
   of the plurality of water injection pipes so that the groundwater pumped up from the pumping pipe passes through a heat exchanger and is injected into the other well at a predetermined flow rate through the plurality of water injection pipes provided in the other well. A program for executing a method for adjusting the opening of the flow control valves provided for each.

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