JP2013076515A - Geothermal utilization system and geothermal utilization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a stable thermal source under ground by using an existing vertical hole.SOLUTION: The geothermal utilization system 1 includes: a medium circulation pipeline 3 which is partially disposed in the vertical hole 2 provided for investigation of earth or ground water, is brought into contact with at least either of earth and ground water in the vertical hole 2 and circulates medium; and a heat pump 6 thermally connected with the medium circulation pipeline 3.

Description

  The present invention relates to a geothermal utilization system and a geothermal utilization method, and more particularly, to a geothermal utilization system using a vertical hole provided for investigation of soil or groundwater.

  Countermeasures are required for organic chlorine compounds such as trichlorethylene and tetrachloroethylene, hydrocarbon compounds such as benzene, heavy metals such as hexavalent chromium and cadmium, oils, and dioxins as a cause of soil and groundwater contamination. When removing these substances, soil samples are often obtained and analyzed in advance by boring. Moreover, in order to investigate groundwater, a casing is installed in the borehole, and a pump is installed in the casing to collect groundwater. A vertical hole with a casing in the borehole is sometimes called an observation well.

“Revised Guidelines on Surveys and Measures Based on the Soil Contamination Countermeasures Law”, Environment Agency, 2011, 126-173 pages

  Such boreholes are often backfilled after collecting a soil sample. In the case of observation wells, groundwater may be maintained for a long period of time, but usually groundwater is collected several times a year and is not used for most periods. On the other hand, the temperature of underground soil or groundwater is almost constant throughout the year and is a stable heat source. Conventionally, boreholes or observation wells have been used only for the original purpose of sampling or groundwater sampling, and no attempt has been made to use them as a heat source.

  An object of the present invention is to provide a geothermal utilization system and a geothermal utilization method capable of effectively utilizing a stable heat source underground using an existing vertical hole.

  The geothermal utilization system according to the present invention is a medium circulation pipe in which a part is provided in a vertical hole provided for investigation of soil or groundwater, and the medium circulates in contact with at least one of soil and groundwater in the vertical hole. And a heat pump thermally connected to the medium circulation pipe.

  In the geothermal heat utilization method according to the present invention, a part of a medium circulation pipe through which a medium circulates is brought into contact with at least one of soil and groundwater in the vertical hole provided for investigation of soil or groundwater. And heat recovery from the medium or heat dissipation to the medium by a heat pump thermally connected to the medium circulation pipe.

  In the present invention, a medium circulation pipe through which the medium circulates is provided in the vertical hole, and heat is recovered from the medium by a heat pump thermally connected to the medium circulation pipe or radiated to the medium. The vertical hole is provided for the investigation of soil or groundwater and does not need to be newly provided for heat recovery or heat dissipation by the heat pump. Utilizing existing vertical holes, it is possible to use a stable heat source in the basement simply by installing a medium circulation pipe and a heat pump.

  ADVANTAGE OF THE INVENTION According to this invention, the geothermal utilization system and geothermal utilization method which can use effectively the stable heat source of the underground using the existing vertical hole can be provided.

It is a schematic block diagram of the geothermal utilization system which concerns on one Embodiment of this invention. It is a schematic block diagram of a heat pump. It is a conceptual diagram which shows the utilization form of a boring hole. It is a conceptual diagram which shows the other utilization form of a boring hole. It is a conceptual diagram which shows the utilization form of an observation well. It is a conceptual diagram which shows the other utilization form of an observation well. It is a conceptual diagram which shows the other utilization form of an observation well.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a geothermal utilization system 1, in which FIG. 1 (a) is a plan view and FIG. 1 (b) is a cross-sectional view.

  The geothermal utilization system 1 is used in combination with the vertical hole 2. As will be described later, the vertical hole 2 is a boring hole 2a or an observation well 2b in which a cylindrical casing 23 is provided inside the boring hole 2a. The vertical hole 2 is formed in advance for investigation of soil or groundwater. Although the present invention is not restricted by the arrangement of the vertical holes 2, it is advantageous that a plurality of the vertical holes 2 are provided in a predetermined area as shown in FIG. When groundwater exists, it is desirable that the vertical hole 2 is excavated deeper than the groundwater level WL so that the groundwater can communicate with the surrounding ground.

  The geothermal utilization system 1 has a medium circulation pipe 3 that holds a medium inside. The medium circulation pipe 3 is provided with a pump 4 so that the medium circulates inside. A part of the medium circulation pipe 3 is inserted into the vertical hole 2, and a part or the whole of the part in the vertical hole 2 of the medium circulation pipe 3 is in contact with soil or ground water or both. The medium flowing through the medium circulation pipe 3 exchanges heat with soil and groundwater at this contact portion. Even if the soil and groundwater are contaminated, the pollutant is not mixed into the medium circulation pipe 3, so that there is no possibility that the pollutant will diffuse to the above-ground part. As shown in FIG. 1A, the medium circulation pipe 3 is a closed loop pipe and is configured to pass through several vertical holes 2 sequentially. The medium circulation pipe 3 has a U-shaped part at the bottom of the vertical hole 2 and is thermally connected to the heat pump 6 at the ground part. As the medium of the medium circulation pipe 3, a glycol-based or organic acid salt-based antifreeze can be used.

  The heat pump 6 uses groundwater and soil as heat sources via the medium in the medium circulation pipe 3. Groundwater is a stable heat source that is generally between 15 and 17 ° C. throughout the year. The soil is also a stable heat source, maintaining a temperature similar to groundwater at a certain depth throughout the year. Therefore, groundwater and soil can be used as a means for heating and cooling air and water. Moreover, the heat pump 6 itself has high energy efficiency, and can heat and cool air and water with low energy as compared with a conventional heating and cooling device using an electric heater, boiler, cooler, or the like.

  FIG. 2 is a schematic configuration diagram of the heat pump 6. In the configuration shown in the figure, water and air supplied from the outside are cooled. Water is supplied through a pipe 11 and air is supplied through a pipe 12. The pipes 11 and 12 are fluid supply passages that are thermally connected to the heat pump 6 and supply a fluid to be cooled. The supplied fluid is cooled using the medium circulating in the medium circulation pipe 3 as a waste heat destination. Water and air can be cooled at the same time, or only one of them can be cooled using a switch (not shown). Any process fluid can be cooled instead of water and air. There is no restriction | limiting in the use of cooled water and air, For example, it can utilize with a water cooler, an air-conditioning installation (cooling mode) etc. centering on the summer.

  The heat pump 6 uses a vapor compression type in this embodiment. The heat pump 6 includes an evaporator 6a that evaporates refrigerant such as ammonia, carbon dioxide, chlorofluorocarbons, and alternative chlorofluorocarbons such as R410A, a compressor 6b that compresses the refrigerant, a condenser 6c that condenses the refrigerant, and a refrigerant. An expansion valve 6d for expansion, and these elements are arranged in this order on the closed loop 6e. The refrigerant undergoes a thermal cycle of evaporation, compression, condensation, and expansion while circulating in the closed loop 6e. The adjacent part between the condenser 6c and the medium circulation pipe 3 forms a heat exchange part 7, and the adjacent part between the evaporator 6a and the pipes 11 and 12 forms a heat exchange part 9.

  Due to the heat of vaporization when the refrigerant evaporates in the evaporator 6a, the heat QC is taken from the water flowing through the pipe 11 and the air flowing through the pipe 12 through the heat exchanging section 9, and the water and air are cooled. The evaporated refrigerant is compressed by the compressor 6b and becomes a high-temperature and high-pressure gas phase. The refrigerant is then sent to the condenser 6c. The condensation heat QH released during the condensation is given to the medium flowing through the medium circulation pipe 3 via the heat exchange unit 7. The condensed refrigerant is cooled under reduced pressure through the expansion valve 6d. In this way, during one cycle of operation of the heat pump 6, water and air are cooled, and heat is released to the medium. The heat applied to the medium is transferred to the groundwater and soil, and the medium returns to the heat exchanging section 7 with the heat pump 6 in a cooled state. For this reason, continuous heat dissipation can be performed in the heat exchange unit 7.

  By exchanging the medium circulation pipe 3 and the pipes 11 and 12, heat recovery from the medium and heating of water and air can be performed. In this case as well, the pipes 11 and 12 are fluid supply passages thermally connected to the heat pump 6, but the supplied fluid is heated using the medium as a heat supply source. There is no restriction | limiting in the use of heated water and air, For example, it can utilize with a water heater, a water heater, an air-conditioning installation (heating mode) etc. centering on winter. There is no particular upper limit on the temperature of air and water that can be heated by the heat pump 6.

  In addition to the vapor compression type, the heat pump 6 may be a thermoelectronic, chemical, adsorption, or absorption heat pump 6.

  The existing vertical hole 2 (boring hole 2a and observation well 2b) can be used by various methods described below. 3 and 4 show the usage of the borehole 2a, and FIGS. 5 to 7 show the usage of the observation well 2b.

  FIG. 3 shows a form in which the boring hole is used as it is. As shown in FIG. 3A, the boring hole 2a is formed by drilling the ground with a boring device and lifting the sample 21 to the ground. Since the boring is performed for the purpose of collecting the sample 21, it is usually backfilled immediately from the state of FIG. In the present embodiment, the medium circulation pipe 3 is installed in the vertical hole 2 as shown in FIG. When groundwater exists, it is desirable to install the medium circulation pipe 3 so that the lowest part (U-shaped part) of the medium circulation pipe 3 is below the groundwater level WL. Next, as shown in FIG. 3C, the boring hole 2 a is backfilled with the backfilling material 22. As a result, the medium circulation pipe 3 is stably embedded in the underground.

  The medium in the medium circulation pipe 3 is cooled or heated by both groundwater and soil. The presence of groundwater is not an essential condition, and the effect of cooling or heating the medium can be obtained only with soil. When groundwater is present, it is desirable that fresh groundwater is always supplied around the medium circulation pipe 3 in order to increase the heat exchange efficiency of the medium circulation pipe 3. For this purpose, it is preferable to use a material with high water permeability so that the backfill material does not block the flow of groundwater. In addition, since the backfill material itself functions as a heat transfer medium, it is preferable that the heat transfer efficiency is high. Examples of such backfilling materials include dredged sand, river sand, and mountain sand.

  FIG. 4 shows a form in which the boring hole is widened and used. After drilling the ground with a boring device as shown in FIG. 4 (a), the boring hole 2a is widened (inner diameter is enlarged) as shown in FIG. 4 (b). Thereafter, as shown in FIG. 4C, the boring hole 2 a is backfilled with the backfilling material 22. The step shown in FIG. 4C can be performed in the same manner as the step shown in FIG. In general boring, a boring hole 2a having an inner diameter of about 86 mm is formed. However, since the radius of curvature of the U portion may be limited by the material, diameter, thickness, and the like of the medium circulation pipe 3, the medium circulation pipe 3 to be installed can be installed by widening the boring hole 2a after sampling the sample 21. Can increase the degree of freedom.

  FIG. 5 shows a form in which the observation well is used as it is. After drilling the ground with a boring device as shown in FIG. 5 (a), a generally hollow cylindrical casing 23 is installed in the boring hole 2a as shown in FIG. 5 (b). The casing 23 extends deeper than the groundwater level WL, and the groundwater can communicate between the inside of the casing 23 and the surrounding ground. The casing 23 is formed of steel, stainless steel, vinyl chloride, or the like, and the side wall of the casing 23 has a large number of through holes (not shown) in order to allow communication of groundwater. The space between the inner wall of the boring hole 2a and the side wall of the casing 23 is filled with gravel, crushed stone, dredged sand 24, etc. in order to promote the fixing of the casing 23 and the communication of groundwater. The water level inside the casing 23 substantially matches the water level WL of the surrounding groundwater. The side wall above the ground water of the casing 23 may be a water-impervious structure such as cement. The observation well 2b is completed through the above steps. Inside the observation well 2b, a water sampler 25, a water absorption pipe (not shown) connected to a pump, or the like can be placed to collect groundwater. The above process is the same as that of the conventional observation well.

  After the use of the observation well 2b for the purpose of collecting groundwater is completed, the medium circulation pipe 3 is installed and the observation well 2b is backfilled with the backfill material 22 as shown in FIG. The process shown in FIG. 5C can be performed in the same manner as the processes shown in FIGS. 3B and 3C. In the present embodiment, since the space between the inner wall of the boring hole 2a and the side wall of the casing 23 is filled with gravel, crushed stone, dredged sand 24, etc. having low heat transfer properties, the medium and the ground in the medium circulation pipe 3 The heat exchange is mainly performed by groundwater. For this reason, in this embodiment, it is desirable that the medium circulation pipe 3 is provided up to a position deeper than the groundwater level WL. As the backfill material 22, it is desirable to use a material equivalent to gravel, crushed stone, dredged sand 24, etc. with emphasis on water permeability.

  After the medium circulation pipe 3 is installed in the casing 23 in the step shown in FIG. 5C, backfilling can be omitted. When the groundwater is flowing, since fresh groundwater always flows into the casing 23, the groundwater having a substantially constant temperature can always be used. At this time, a lid as shown in FIG. 7 can be installed on the ground surface.

  FIG. 6 shows a form in which the observation well is expanded and used. After drilling the ground with a boring device as shown in FIG. 6 (a), the boring hole 2a is widened (inner diameter is enlarged) as shown in FIG. 6 (b). This step can be performed similarly to the step shown in FIG. After that, as shown in FIG. 6C, the casing 23 is installed, and the inner wall of the boring hole 2a and the side wall of the casing 23 are filled with gravel, crushed stone, dredged sand 24, and the like. This step can be performed similarly to the step shown in FIG. Thereafter, as shown in FIG. 6D, the medium circulation pipe 3 is installed in the casing 23, and the observation well 2 b is backfilled with the backfill material 22. This step can be performed similarly to the step shown in FIG. In this embodiment, it is necessary to widen the observation well 2b in advance, but the degree of freedom of the installed medium circulation pipe 3 can be increased as in the embodiment of FIG.

  FIG. 7 shows a form in which the observation well is left without performing the backfilling process in the example of FIG. After drilling the ground with a boring device as shown in FIG. 7 (a), the steps shown in FIGS. 7 (b) and 7 (c) are performed in the same manner as the steps shown in FIGS. 6 (b) and 6 (c). Thereafter, as shown in FIG. 7D, the medium circulation pipe 3 is installed in the casing 23, and the opening of the observation well 2b is covered with a lid 26 without backfilling the observation well 2b. The medium circulation pipe 3 passes through the lid 26. The lid 26 prevents dust, rainwater and the like from entering the observation well 2b, and also blocks the inside of the observation well 2b from outside air to reduce the influence received from the ground. The lid 26 can be omitted depending on the installation environment of the observation well 2b.

  The observation well 2b may be used for a long time for the purpose of collecting groundwater. In the present embodiment, the observation well 2b is normally used as a heat source of the heat pump 6, and the observation well 2b can be temporarily used for the purpose of collecting groundwater. For example, an opening 27 for collecting groundwater in the observation well 2b is provided in the lid 26, and a pumping pump 28 is installed in the observation well 2b through the opening 27, or the water sampler 25 is lowered to remove the groundwater. Can be collected. Therefore, the observation well 2b can be used as a heat source at the same time while being used for the original purpose. You may provide the cover (not shown) which covers the opening part 27 as needed.

  Instead of the present embodiment, as shown in FIG. 7E, the medium circulation pipe 3 and the groundwater collecting pump 28 may be permanently installed in the observation well 2b. In this case, the pumping pump 28 is connected to the pumping pipe 29 penetrating the lid 26 in the same form as the medium circulation pipe 3, and the collected groundwater can be collected on the ground. Also in this embodiment, the observation well 2b can be used as a heat source at the same time while being used for the original purpose.

DESCRIPTION OF SYMBOLS 1 Geothermal utilization system 2 Vertical hole 2a Boring hole 2b Observation well 3 Medium circulation piping 6 Heat pump

Claims (8)

A medium circulation pipe that is partially provided in a vertical hole provided for investigation of soil or groundwater, contacts with at least one of soil and groundwater in the vertical hole, and the medium circulates;
A heat pump thermally connected to the medium circulation pipe;
A geothermal heat utilization system.   The geothermal heat utilization system according to claim 1, wherein the vertical hole is a borehole or an observation well provided with a cylindrical casing inside the borehole.   The casing extends deeper than the groundwater level, and the groundwater can communicate between the inside of the casing and the surrounding ground, and the medium circulation pipe is provided to a position deeper than the groundwater level. The geothermal utilization system according to claim 2.   The geothermal heat utilization system according to any one of claims 1 to 3, wherein the vertical hole is backfilled.   The lid is provided at the opening of the vertical hole, the medium circulation pipe passes through the lid, and the lid has an opening for collecting groundwater in the vertical hole. The geothermal utilization system according to any one of the above.   A lid is provided at the opening of the vertical hole, the medium circulation pipe passes through the lid, a pump is installed in the vertical hole, and the pump is connected to a pumping pipe that passes through the lid. The geothermal utilization system according to any one of claims 1 to 3.   7. The fluid supply passage according to claim 1, further comprising: a fluid supply passage that is thermally connected to the heat pump and supplies a fluid that is heated using the medium as a heat supply source or cooled as a waste heat destination. Heat utilization system. In a vertical hole provided for investigation of soil or groundwater, a part of a medium circulation pipe through which the medium circulates is provided in contact with at least one of soil and groundwater in the vertical hole;
Recovering heat from the medium or dissipating heat to the medium by a heat pump thermally connected to the medium circulation pipe;
A geothermal heat utilization method.

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