JP6537112B2 - Freezing method - Google Patents

Description

  The present invention relates to a freezing method, and more particularly to a freezing method capable of preventing compression deformation of a refrigerant pipe.

In the freezing method, for example, a boring hole is excavated in the ground by a drilling casing, and then the drilling casing is pulled to the ground side, refrigerant piping is inserted into the excavated boring hole, and the refrigerant is circulated in the refrigerant piping. Then, the soil of a predetermined range is frozen by cold heat of the refrigerant, and underground walls and other desired underground solid bodies are created.
Here, a sheath pipe is inserted in the boring, and in order to conduct cold heat to the soil, the sheath pipe is filled with a fluid (for example, water) having a heat transfer performance.

However, when circulating the refrigerant through the refrigerant pipe, it is the refrigerant at the initial stage of circulation that releases the cold heat, and the refrigerant flows on the refrigerant supply side of the borehole, usually in the region above the borehole.
Therefore, the fluid having the heat transfer performance, which is filled in the sheath pipe, is first supplied with the cold heat of the refrigerant in the region above the borehole.
Then, when the fluid having the heat transfer performance with which the sheath pipe is filled is water, the water in the region above the borehole is charged with the cold heat of the refrigerant and is first frozen, and the water is transferred downward. Freezing of water proceeds.

Here, when the water freezes and becomes ice, the volume expands. As described above, when the water turns into ice and expands to increase the volume because it freezes from the upper area to the lower area, the area above the borehole is closed with ice (ice previously frozen) Because of this, the pressure due to volumetric expansion can not escape above the borehole.
On the other hand, unfrozen water exists below the borehole, and even if pressure is applied due to volume increase, the water below the borehole can not be compressed from above. That is, the pressure generated by the volume increase can not be absorbed by the water below the borehole.

As a result, the water turns into ice and the pressure generated by volume expansion acts to compress the refrigerant pipe. When the compression strength of the refrigerant pipe is exceeded, the refrigerant pipe is compressed and deformed by ice, and the flow passage cross-sectional area decreases.
When the flow passage cross-sectional area of the refrigerant pipe decreases, it becomes difficult to circulate the refrigerant at a predetermined flow rate, and it becomes difficult to freeze the soil in a predetermined range well. Then, if the refrigerant piping is destroyed without being able to withstand the pressure of ice, the refrigerant is not circulated, and there is a problem that it is not possible to freeze the soil in the area where the frozen earth wall etc should be created. .

As another prior art, the technique which forms the borehole which filled the filling material with formation frozen soil is proposed (refer patent document 1).
However, the related art (see Patent Document 1) aims to reduce the influence on the underground structure around the frozen soil, and is not a technology for solving various problems due to the compression deformation of the refrigerant pipe as described above.

Unexamined-Japanese-Patent No. 8-338016

  The present invention has been proposed in view of the problems of the prior art described above, and even if the fluid having heat transfer performance is frozen and volumetrically expanded, the refrigerant pipe is not compressed, and proper circulation of the refrigerant can be achieved. The purpose is to provide a freezing method that can be maintained.

In the freezing method of the present invention, a refrigerant pipe (FP) and a heat insulating material (I: a flexible or flexible heat insulating material: for example, expanded styrene) are inserted into the borehole (1) and the heat transfer fluid ( W: for example, water is filled, and each refrigerant pipe (FP) has a flow path (LS: refrigerant supply side flow path) through which the refrigerant flows toward the opposite side (for example, the underground side) to the supply side , Both of the flow paths (LO: refrigerant return side flow path) in which the refrigerant flows toward the supply side (for example, the ground side),
Heat conductive material (for example, carbon dioxide) which takes heat (sensible and / or latent heat) from the surroundings as it flows through the refrigerant pipe (FP) and freezes, filling the inside of the borehole (1) W: water) and surrounding soil (G),
It is characterized in that the heat insulating material (I) is compressed and deformed by the pressure generated by the volumetric expansion of the frozen heat transfer fluid (W).

In the present invention, it is preferable to insert the hollow member into the borehole (1) and insert the refrigerant pipe (FP) and the heat insulating material (I) into the internal space of the hollow member.
Here, the hollow member is preferably a sheath pipe (2), or it is preferable that the hollow member be a boring hole drilling casing in which the hollow member is left in the ground.
In the freezing method of the present invention, the thermally conductive material discharge pipe (WP) coated with the heat insulating material (I) is inserted into the hollow member (for example, the sheath pipe 2 and the boring hole drilling casing);
The pressure generated by the volumetric expansion of the frozen heat transfer fluid (W) causes the heat insulating material (I) to be compressed and deformed, and an area (AD) separated from the refrigerant supply side (for example, the refrigerant supply facility side on the ground) in the hollow member Preferably, the heat transfer fluid (W) is pressed and discharged out of the hollow member through the heat transfer material discharge pipe (WP).

Further, in the freezing method of the present invention, the boring (1) hole extending vertically upward is bored, and the lower end of the hollow member (for example, sheath pipe 2 and boring hole drilling casing) is closed by a lid (3) The refrigerant pipe (FP) and the heat transfer material discharge pipe (WP) penetrate the lid (3), and the heat transfer material discharge pipe (WP) is provided with an on-off valve (V). The pressure difference between the lid (3) and the pressure of the heat transfer fluid (eg, water) in the area (ADU) above the borehole (1) is the head difference (H = ρgh: ρ is filled in the hollow member) Specific gravity of insulating fluid, g is the acceleration of gravity, h is the difference in height between the location where the on-off valve V is provided and the area ADU above the borehole) Has the function of closing in the following cases,
The heat transfer fluid (W) is frozen from the area under the borehole (1) to the area (ADU) sequentially from the area under the borehole (1) by the cold heat held by the refrigerant flowing through the refrigerant pipe (FP) When generated, the pressure acting on the lid (3) may be increased to open the on-off valve (V), and the heat transfer fluid (W) may be discharged from the hollow member.

According to the present invention having the above-described configuration, the refrigerant (for example, liquid-phase refrigerant of carbon dioxide) flowing through the refrigerant pipe (FP) takes heat (sensible heat and / or latent heat) from the surroundings and is vaporized to be gas-liquid It becomes a two-phase flow and ascends the refrigerant pipe (FP) and returns to the ground side. At that time, the cold stored in the refrigerant is transmitted to the heat transfer fluid (W) and the surrounding soil (G), and freezes the soil (G) around the borehole (1).
Here, in the present invention, since the heat insulating material (I) is inserted together with the refrigerant pipe (FP), the refrigerant flows in the refrigerant pipe (FP), and the heat transfer fluid (W: For example, even if water freezes and pressure is generated by volumetric expansion, the pressure acts to compress and deform the heat insulating material (I) and does not compress the refrigerant pipe (FP). Therefore, the flow path in the refrigerant pipe (FP) is prevented from being deformed, the flow path cross-sectional area is prevented from being reduced, and the refrigerant is maintained in a properly circulated state.
In the present invention, in each refrigerant pipe (FP), a flow path (LS: refrigerant supply side flow path) through which the refrigerant flows toward the opposite side (for example, the underground side) to the supply side (the refrigerant supply side) For example, the freezing method in which both of the flow paths (LO: refrigerant return side flow path) flowing toward the ground side are provided is targeted.

Here, the reason that the refrigerant flowing through the refrigerant pipe (FP) most releases cold energy is the refrigerant flowing through the end of the refrigerant pipe (FP) on the refrigerant supply side (the ground side in FIGS. 1, 3 and 4) The heat transfer fluid (W: water) is frozen from the refrigerant supply side (the upper part of FIG. 1, FIG. 3 and FIG. 4), and is sequentially separated from the refrigerant supply side (FIG. 1, FIG. 3 and FIG. Freeze down).
In the present invention, when the heat transfer material discharge pipe (WP) is covered with the heat insulating material (I) and the heat transfer material discharge pipe (WP) is inserted into the borehole (1), the heat transfer fluid (W) Even if pressure is generated due to volume expansion, the pressure presses the non-freezing heat transfer fluid (W) present in the area AD (downward in FIG. 4) separated from the refrigerant supply side, and heat insulation It acts like discharging to the outside of the borehole (1) (arrow OF) via the heat transfer material discharge pipe (WP) coated with the material (I). That is, in addition to the compressive deformation of the heat insulating material I, the heat transfer fluid (W) is discharged out of the borehole (1) through the heat transfer material discharge pipe (WP) in addition to the pressure generated by the volumetric expansion. Thus, the refrigerant pipe (FP) can be released without compression.
Therefore, the refrigerant pipe (FP) is not compressed, the flow path is not deformed, the flow path cross-sectional area is not reduced, and the refrigerant is properly circulated.

  In the present invention, a hollow member (for example, sheath pipe 2 and boring hole drilling casing) is inserted into the borehole (1), the lower end of the hollow member is closed by the lid (3), and the lid (3) Piping (FP) and the heat transfer material discharge pipe (WP) penetrate, the heat transfer material discharge pipe (WP) is provided with the on-off valve (V), and the on-off valve (V) acts on the lid (3) Pressure is the pressure of the heat transfer fluid (eg, water) in the area (ADU) above the borehole (1) (H == gh: ρ is the specific gravity of the heat transfer fluid filled in the hollow member, g Is the gravity acceleration, h is the difference between the pressure at the location where the on-off valve V is provided and the height of the area ADU above the borehole (1)) Pressure acting on the lid (3) If the on-off valve (V) is opened and the heat transfer fluid (W) is discharged from the hollow member, the borehole (1) is drilled upward to freeze the upward region It is possible.

In this case, the heat transfer fluid (W) in the hollow member freezes from the area under the borehole (1) and sequentially freezes toward the upper area (ADU). Although the lower end of the hollow member is closed by the lid (3), the pressure of the heat transfer fluid (W: water, for example) in the hollow member is caused by freezing and volumetric expansion of the heat transfer fluid (W) in the hollow member. Increases, and the pressure acting on the on-off valve (V) becomes greater than the pressure in the upper area (ADU) plus the head difference (H = ghgh). As a result, the on-off valve (V) provided on the lid (3) is opened, and the heat transfer fluid (W) flows out (discharges) downward from the heat transfer material discharge pipe (WP).
In addition to the compressive deformation of the heat insulating material I, the heat transfer fluid (W) in the hollow member flows out of the heat transfer material discharge pipe (WP) to transfer the area above the borehole (1) (ADU) The pressure generated by freezing and volumetric expansion of the thermal fluid (W) is released, and the refrigerant pipe (FP) is not compressed. Therefore, the circulation of the refrigerant is properly performed.

It is an explanatory view showing a 1st embodiment of the present invention. It is a fragmentary perspective view showing an example of piping for refrigerants used by an embodiment. It is an explanatory view showing the modification of a 1st embodiment. It is an explanatory view showing a 2nd embodiment of the present invention. It is an explanatory view showing a 3rd embodiment of the present invention. FIG. 2 is a partial cross-sectional side view of the dispensing and collecting device used in the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The illustrated embodiment describes the case where carbon dioxide (CO ₂ ) is adopted as the refrigerant. However, the refrigerant is not limited to carbon dioxide, and any refrigerant capable of supplying cold energy sufficient to freeze the soil can be applied.
The first embodiment of the present invention will be described first with reference to FIG.
In the first embodiment, the boring hole 1 extending downward in the vertical direction is drilled to freeze the soil G around it.

In FIG. 1, the borehole 1 is drilled with a drilling casing (not shown). Then, the drilling casing is pulled out from the drilled boring hole 1 to the ground side, and the sheath pipe 2 is inserted into the boring hole 1. The bottom of the sheath pipe 2 is closed, and the diameter of the sheath pipe 2 is set to be approximately equal to the diameter of the borehole 1.
Here, there is a case where the sheath pipe 2 is inserted in a state where a digging casing (not shown) remains in the ground, and then the digging casing is pulled to the ground side.
Moreover, although the bottom of the sheath pipe 2 is closed in the illustrated embodiment, there are cases where the bottom of the sheath pipe 2 is not closed. When the bottom of the sheath pipe 2 is not closed, the digging casing (not shown) of the borehole 1 is left in the ground and the sheath pipe 2 is not used, that is, Instead, there is a case where the drilling casing (not shown) of the borehole 1 remaining in the ground is used.

The sheath pipe 2 uses a steel pipe or the like excellent in heat conductivity, but may be made of a flexible material.
If the sheath pipe 2 is made of a flexible material, the fluid W having heat transfer performance in the sheath pipe 2 (in the illustrated embodiment, water or various aqueous solutions) after drilling the borehole 1 with the drilling casing The sheath pipe 2 expands radially outward due to the weight of the fluid having heat transfer performance, and the sheath pipe 2 adheres to the inner wall of the borehole 1 and the cold heat of the refrigerant is to be frozen to the soil G It is advantageous because it is conducted effectively.

After inserting the sheath pipe 2 into the borehole 1, the heat insulating material I having flexibility and the refrigerant pipe FP are inserted into the sheath pipe 2. Here, in the refrigerant pipe FP, a refrigerant supply side flow passage LS (shown as an arrow in the drawing) and a refrigerant return side flow passage LO (shown as an arrow in the drawing) are formed.
A fluid W (for example, water) having a heat transfer performance is filled in the sheath pipe 2, and the fluid W having a heat transfer performance has an effect of conducting the cold heat of the refrigerant to the sheath pipe 2.
Here, water is suitable for being filled in the sheath pipe 2 as a fluid W having heat transfer performance, since it has good heat transfer and is easy to handle and safe. However, the fluid W having heat transfer performance is not limited to water.

As the heat insulating material I, a material rich in flexibility (or flexibility) such as, for example, expanded styrene having a continuous foam structure is selected. Here, the function required of the heat insulating material I is softness (or flexibility) rather than heat insulating property, and the heat insulating material I is selected with priority given to softness (or flexibility).
Further, the position of the heat insulating material I in the sheath pipe 2 is not particularly limited as long as it is a position near the refrigerant pipe FP when the refrigerant pipe FP is only one. On the other hand, when a plurality of refrigerant pipes FP are inserted into the sheath pipe 2, it is preferable to interpose the heat insulating material I at a position between the plurality of refrigerant pipes FP.

In FIG. 1, when the refrigerant (liquid phase carbon dioxide) is supplied from the ground side refrigerant supply facility (not shown: for example, a refrigerator), the liquid phase refrigerant is the refrigerant supply side flow path LS in the refrigerant pipe FP. (Arrow AR1). Since the liquid phase refrigerant has a large specific gravity, it descends in the refrigerant supply channel LS.
The refrigerant which descends the refrigerant supply side channel LS reaches the lowermost part of the boring hole 1 (sheath pipe 2) while supplying cold heat to the surrounding soil G.

The liquid phase refrigerant (liquid carbon dioxide) that has taken heat (sensible heat and / or latent heat) from the surrounding soil G becomes a gas phase refrigerant or a gas-liquid two-phase refrigerant, and since the gas phase refrigerant has a small specific gravity, The refrigerant return side flow path LO in the piping FP is immediately raised, and the gas-liquid two-phase refrigerant is a gas phase refrigerant entraining the liquid phase refrigerant to immediately rise the refrigerant return side flow path LO.
Then, while rising in the refrigerant return side flow path LO, the refrigerant deprives the soil G in the vicinity of the sheath pipe 2 of heat (sensible heat and / or latent heat) to freeze the surrounding soil G.

The refrigerant falling in the refrigerant supply side flow passage LS and the cold held by the refrigerant rising in the refrigerant return side flow passage LO are refrigerant pipes FP, water W (fluid having heat transfer performance), sheath pipe 2, freezing The heat is transferred in the order of the soil G to be done, and the soil G (the soil to be frozen) around the borehole 1 is frozen. Here, since the heat insulating material I does not surround the refrigerant pipe FP, the cold heat from the refrigerant is not blocked by the heat insulating material I, and through the water W (fluid having heat transfer performance) and the sheath pipe 2 It is transmitted to the surrounding soil G.
And if frozen soil G is adjacently created and a predetermined number is produced, a water blocking wall can be easily constructed.
The refrigerant which has risen in the refrigerant return side flow path LO is then returned to the refrigerant supply facility on the ground side (arrow AR2).

Although two refrigerant pipes FP are shown in the sheath pipe 2 in FIG. 1, the number of refrigerant pipes FP may be one or three or more. It is not necessarily limited to this number. The number of refrigerant pipes FP may be appropriately determined along with the shape and size of the sheath pipe 2 according to the size of the frozen and frozen soil to be created and the environmental conditions of the construction site.
Further, the refrigerant pipe FP may be a multi-pipe or a pipe L of a rectangular cross section having a plurality of flow paths Lδ (so-called “micro channel”) as shown in FIG. However, as the refrigerant pipe FP, the refrigerant supply side flow passage LS and the refrigerant return side flow passage LO are formed inside, and the flow of the refrigerant (the flow of the refrigerant in the refrigerant supply side flow passage LS) toward the underground side , That there is a flow of refrigerant returning to the ground side (a flow of refrigerant in the refrigerant return side flow path LO), so that there are two opposite directions of refrigerant flow in a single refrigerant pipe FP is necessary.

The structure shown in FIG. 2 can be applied as an example of the structure of the refrigerant pipe FP.
In FIG. 2, the refrigerant pipe L (microchannel) formed of a flat member as a whole has a structure in which a plurality (10 in FIG. 2) of refrigerant flow paths Lδ having rectangular cross sections are provided. Although not clearly illustrated, in the plurality of refrigerant flow paths Lδ, flow paths Lδ of a portion (for example, 5) of the refrigerant flow paths Lδ constitute the refrigerant supply side flow path LS, and the remaining portion (for example, 5) The flow path Lδ constitutes the refrigerant return side flow path LO.
Here, the refrigerant pipe FP is made of, for example, aluminum, and has excellent heat transfer performance.

Although illustration is omitted, in the case where the refrigerant pipe FP is a multiple pipe (for example, a double pipe), the inner pipe of the double pipe constitutes the refrigerant supply side flow path LS, and the radially outer circle of the inner pipe The annular space (outer pipe) constitutes the refrigerant return side flow path LO. However, it is also possible that the outer pipe constitutes the refrigerant supply side flow path LS and the inner pipe constitutes the refrigerant return side flow path LO.
When the refrigerant pipe FP is a multiple pipe (for example, a double pipe), the water W (a fluid having a heat transfer performance) is filled in the region between the radially outermost shell of the double pipe and the sheath pipe 2 .
Even when the refrigerant pipe FP is configured by microchannels or double pipes (multiple pipes), the number of the microchannels or double pipes (multiple pipes) may be more than one.

Although not shown, at the lowermost part of the borehole 1, the refrigerant coming out of the refrigerant supply side channel LS is guided to the refrigerant return side channel LO in a mode not mixed with the water W, and the refrigerant return side flow It is possible to provide a mechanism for raising the inside of the road LO, and a conventionally known mechanism can be adopted as the mechanism.
Since the refrigerant of the illustrated embodiment is carbon dioxide (CO ₂ ), as described above, the liquid-phase refrigerant (supplied refrigerant) takes heat (sensible or latent heat) from the soil and is vaporized. In the refrigerant return side flow path LO, the gas phase refrigerant immediately rises, and the gas-liquid two-phase refrigerant immediately rises as the gas phase refrigerant entrains the liquid phase refrigerant. Therefore, in the case where the refrigerant is carbon dioxide and the refrigerant pipe FP is constituted by a multi-pipe (for example, a double pipe), the mechanism for lowering or elevating the refrigerant can be omitted.

When the refrigerant is supplied from the refrigerant supply facility (not shown) on the ground side into the refrigerant pipe FP, the periphery (including the soil G) freezes from the area above the borehole 1 toward the area below. Then, since the sheath pipe 2 is filled with water which is a fluid W having heat conductivity, the water W in the region above the borehole 1 is frozen, and the freezing of the water W proceeds toward the lower region.
Although the volume expands when the water W freezes and becomes ice, as described above, since it becomes ice from the upper area to the lower area, even if the water W becomes ice and expands, the volume increases, The pressure due to volumetric expansion can not escape above the borehole 1 because the area above it is closed by ice.

However, in the embodiment of FIG. 1, the heat insulating material I is inserted in the vicinity of the refrigerant pipe FP, and the heat insulating material I is a material having high flexibility or flexibility (for example, expanded styrene having a continuous foam structure). Since the water W is frozen to form ice and volume expansion is performed, the volume expansion is absorbed by compressive deformation of the heat insulating material I.
Therefore, the pressure generated by volumetric expansion of the water W as ice does not act to compress the refrigerant pipe FP, the refrigerant pipe is deformed by the pressure, and the flow path cross-sectional area is prevented from decreasing. The circulation of the refrigerant is properly performed.

As a modification of the first embodiment of FIG. 1, the case of so-called “limited freezing” is shown in FIG.
In the case of the limited freezing of FIG. 3, it is not necessary to freeze the entire region in the vertical direction (vertical direction in FIGS. 1 and 3) of the ground G, and it is sufficient to freeze only the region indicated by the arrow L in FIG. Therefore, the refrigerant pipe FP is installed only in the area (area indicated by the arrow L), and the ground side end (upper end in FIG. 3) of the refrigerant pipe FP is formed of a normal pipe covered with a heat insulating material The refrigerant supply piping (indicated by arrow OLS) and the refrigerant return piping (indicated by arrow OLO) are connected. If the other end of the refrigerant supply pipe (arrow OLS) and the refrigerant return pipe (arrow OLO) are connected to the refrigerant supply facility (not shown) on the ground side, the refrigerant can be circulated as in FIG.
In FIG. 3, the heat insulating material I is disposed in the area (the area indicated by the arrow L) in which the refrigerant pipe FP is disposed, and the heat insulating material I is not disposed in the area above it.

According to the modification of FIG. 3, the freezing target can be limited to a required place, and ground freezing can be efficiently constructed.
Other configurations and effects in the modification of FIG. 3 are the same as those described with reference to FIGS. 1 and 2.

Next, with reference to FIG. 4, a second embodiment of the present invention will be described mainly regarding differences from FIGS. 1 and 3.
In the embodiment of FIGS. 1 to 3, only the refrigerant pipe FP and the heat insulating material I are inserted in the sheath pipe 2, but in the second embodiment of FIG. The pipe WP is arranged. In other words, in FIG. 4, the heat transfer fluid discharge pipe WP covered with the heat insulating material I is provided. Here, also in the second embodiment of FIG. 4, since water is used as the heat transfer fluid, the heat transfer fluid discharge pipe WP is hereinafter referred to as the drainage pipe W.
The refrigerant pipe FP (the refrigerant supply pipe LS and the refrigerant return pipe mark LO) in the second embodiment is the same as that in the first embodiment.

The lower end portion of the drainage pipe WP projects downward from the lower end of the heat insulating material I and opens to the lowermost region AD in the sheath pipe 2, and the upper end portion of the drainage pipe WP projects upward from the upper end of the heat insulating material I It opens in the area outside pipe 2.
About the position which arranges drainage pipe WP covered with heat insulating material I in sheath pipe 2, as in the first embodiment, when there is only one refrigerant pipe FP, it is at a position near refrigerant pipe FP. In the case where a plurality of refrigerant pipes FP are inserted, they are interposed at positions between the plurality of refrigerant pipes FP.

In FIG. 4, when the refrigerant is supplied from the refrigerant supply facility (not shown) on the ground side into the refrigerant pipe FP, it is at the position on the refrigerant supply side most where the refrigerant releases the cold heat. At the top of the Then, the water W filled in the sheath pipe 2 is frozen from the area above the borehole 1 and is sequentially frozen toward the lower area.
In FIG. 4, the lowermost area AD in the sheath pipe 2 and the area outside the sheath pipe 2 (the ground side area above the sheath pipe 2) are communicated by the drainage pipe WP. Therefore, even if the water W filled in the region inside the borehole 1 freezes from the upper region and becomes ice and volume expansion and pressure is generated, the pressure is present in the region AD below the sheath pipe 2 The unfreezed water W is pushed upward of the sheath pipe 2 through the drainage pipe WP. And water W pushed up is discharged from the upper end of drainage pipe WP (arrow OF).

That is, even if the water W in the region above the sheath pipe 2 freezes and pressure is generated by volumetric expansion, the pressure acts to discharge the water W below the sheath pipe 2 (via the drainage pipe WP). , The refrigerant pipe FP is not compressed. This is because the pressure required to discharge the water W under the sheath pipe 2 as indicated by the arrow OF is much smaller than the pressure for compressing and deforming the refrigerant pipe FP.
In other words, the pressure generated by freezing and volumetric expansion of the water W in the area above the borehole 1 is relieved by the water W below the sheath pipe 2 being drained through the drainage pipe WP (arrow OF) Therefore, the refrigerant pipe FP is not compressed and deformed.
Then, the refrigerant pipe FP is not compressed, the flow path is not deformed, the flow path cross-sectional area is not reduced, and the refrigerant pipe FP is not damaged. Therefore, the refrigerant is properly circulated.

In addition, as in the first embodiment of FIGS. 1 and 2, in the second embodiment of FIG. 4, the heat insulating material I is inserted in the vicinity of the refrigerant pipe FP, and the heat insulating material I has a continuous foam structure Since the water W is frozen to form ice and volume expansion occurs, the volume expansion is caused by deformation of the heat insulating material I because the material is made of a material having high flexibility or flexibility such as expanded styrene having the Absorbed
The synergetic effect of draining through the drainage pipe WP (arrow OF) and compression deformation of the heat insulating material I does not deform or break the refrigerant pipe FP, and the refrigerant is properly circulated.
The other configuration and effects in the second embodiment of FIG. 4 are the same as those of the embodiment shown in FIGS. 1 to 3.

Next, a third embodiment of the present invention will be described with reference to FIG.
The third embodiment shown in FIG. 5 has a configuration in which the second embodiment shown in FIG. 4 is upside down. And 3rd Embodiment of FIG. 5 is a case where it has the drainage pipe WP (heat conductive material discharge pipe) coat | covered with the heat insulating material I similarly to 2nd Embodiment of FIG. It is applied when drilling the boring hole 1 and freezing the surrounding soil G.
Hereinafter, points different from the second embodiment of FIG. 4 will be mainly described with reference to FIG.

In FIG. 5, the sheath pipe 2 is inserted vertically upward into the borehole 1, and the refrigerant pipe FP and the drainage pipe WP covered with the heat insulating material I are disposed in the sheath pipe 2. The configuration and effects of the refrigerant pipe FP and the drainage pipe WP covered with the heat insulating material I are the same as those in the second embodiment of FIG. 4.
The lower end of the sheath pipe 2 is closed by a lid 3. This is to prevent the water W filled in the sheath pipe 2 from flowing out.

In the lid 3, the refrigerant pipe FP and the drainage pipe WP are penetrated maintaining sealing performance, and the drainage pipe WP is provided with an on-off valve V. The on-off valve V is released when the pressure acting on the (on-off valve V) is larger than the pressure obtained by adding the head difference H to the pressure of water in the area ADU above the borehole 1, but below Close to
The “head difference H” is represented by the equation “head difference H = ρgh” when the difference in height between the lid 3 and the area ADU above the borehole 1 is indicated by the symbol “h” (ρ is in the sheath pipe 2 Specific gravity of water W filled in (g is gravitational acceleration).
When opening and closing the on-off valve V, for example, using a conventionally known control device (not shown), the pressure acting on the lid 3, the pressure of the water W in the area ADU, the head difference H (ρgh) is detected and calculated. I can do it.

Although not clearly illustrated, the liquid-phase refrigerant flowing in the refrigerant supply side flow path LS of the refrigerant pipe FP is added with a head by a refrigerant supply facility on the ground side (not shown in FIG. 5). , Rises in FIG.
Then, by setting the pressure on the refrigerant return side of the refrigerant supply facility (not shown) to a pressure lower than the pressure in the refrigerant return side flow path LO, the pressure in the refrigerant return side flow path LO of the refrigerant pipe FP is lowered.

When the refrigerant is supplied from the refrigerant supply facility into the refrigerant pipe FP, it is the refrigerant which rises from the refrigerant supply side and discharges the cold heat most in FIG. 5 and flows through the vicinity of the lid 3. Therefore, the water W in the sheath pipe 2 is sequentially frozen from the area near the lid 3 toward the upper area.
As described above, the lower end of the sheath pipe 2 is closed by the lid 3. However, when the pressure of the water W in the sheath pipe 2 is increased by freezing and volumetric expansion of the water W in the area near the lid 3 of the sheath pipe 2, the pressure acting on the on-off valve V is the pressure in the area ADU The pressure difference due to the head difference H (高 く gh) is higher than the applied pressure.
Therefore, the on-off valve V interposed in the drainage pipe WP is opened, and the water W flows out (discharges) downward from the on-off valve V (arrow FO).

The on-off valve V is opened, and the water W in the sheath pipe 2 flows downward from the on-off valve V interposed in the drainage pipe WP, whereby the water W in the region near the lid 3 is frozen and volumetrically expanded. The generated pressure is released and the refrigerant pipe FP is not compressed.
In addition to that, even if the water W freezes and becomes ice and volume expansion occurs, the volume expansion is absorbed by compression deformation of the heat insulating material I, so the refrigerant pipe FP is deformed or damaged The circulation of the refrigerant is properly performed without
Therefore, also in the third embodiment of FIG. 5, the refrigerant pipe FP is not compressed, the flow path is not deformed, the flow path cross-sectional area is not reduced, and the refrigerant pipe FP is not damaged. The circulation of the refrigerant is properly performed.

When a certain amount of water W is discharged from the opened on-off valve V and the pressure in the sheath pipe 2 decreases, the pressure acting on the on-off valve V adds the pressure (ρgh) by the head difference H to the pressure in the area ADU. The on-off valve V is closed.
The other configuration and operational effects in the third embodiment of FIG. 5 are the same as those of the embodiment of FIGS.

FIG. 6 shows a distribution / aggregation device 4 preferably used in the illustrated embodiment. A plurality (for example, 10) of frozen pipes from a refrigerant supply facility on the ground side (not shown) (boring holes shown in FIG. 1 and FIGS. 3 to 5, sheath pipes, refrigerant pipes: hereinafter collectively referred to as “connection pipes”) Supply liquid-phase carbon dioxide, which is the refrigerant, and distribute the liquid-phase refrigerant to a plurality of (for example, 10) freezing tubes and / or from the plurality (for example 10) freezing tubes The structure is suitable for collecting carbon dioxide.
In the distribution / collection apparatus 4 of FIG. 6, when the refrigerant is supplied (distributed) from the refrigerant supply facility on the ground side to the freezing pipe, the refrigerant from the refrigerant supply facility flows into the distribution / collection apparatus 4 from the supply side outlet / inlet 4A. (Arrow AR31), it is distributed (supplied) to the freeze tube side from the freeze tube side outlet 4B (provided) (arrow AR32). Further, when the refrigerant is returned (gathered) from the freezing pipe to the refrigerant supply facility (not shown), the refrigerant from the freezing pipe side flows into the distribution / collection device 4 from the freezing pipe side outlet / inlet 4B (arrow AR41), the supply side It returns to a refrigerant | coolant supply installation from the outflow inlet 4A (arrow AR42).
In FIG. 6, reference numeral 5 (indicated by a dotted line) denotes an intermediate pipe that communicates the distribution / collection device 4 with the freezing pipe.

Since carbon dioxide in the liquid phase, which is a refrigerant, has almost no viscosity, the distribution / aggregation device 4 as shown in FIG. 6 distributes the liquid phase refrigerant at a uniform flow rate to refrigerant pipes of a plurality of (for example, ten) freezing pipes. It can be supplied. Thereby, the quality of the created frozen soil wall can be improved.
Further, if the distribution / aggregation device 4 of FIG. 6 is used, it is not necessary to use a header (not shown) in the prior art, so the entire equipment can be made compact and space saving can be achieved.

It should be noted that the illustrated embodiment is merely an example, and is not a description for the purpose of limiting the technical scope of the present invention.
For example, in the embodiment of FIG. 5, it is possible not to have the drainage pipe WP and the on-off valve V, and to absorb the pressure generated by freezing of the water only by the heat insulating material I.

DESCRIPTION OF SYMBOLS 1 ... Boring hole 2 ... Sheath pipe 3 ... Lid 4 ... Distribution and collection device 4A ... Supply side outflow port 4B ... Freezing pipe side outflow port 5 ... Intermediate piping FP · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ... Pump for refrigerant supply V ... on-off valve
W · · · Water WP · · · heat transfer material discharge pipe

Claims (6)

A refrigerant pipe and a heat insulating material are inserted into the borehole and the heat transfer fluid is filled, and each refrigerant pipe has a flow path through which the refrigerant flows toward the opposite side to the supply side, and a refrigerant supply side Both of the flow channels towards the
As the coolant flows in the coolant pipe, it takes heat from the surroundings and freezes it, and freezes the thermally conductive material filling the borehole and the surrounding soil,
A freezing method characterized in that a heat insulating material is compressed and deformed by pressure generated by volume expansion of frozen heat transfer fluid.   The freezing method according to claim 1, wherein the hollow member is inserted into the borehole, and the refrigerant pipe and the heat insulating material are inserted into the internal space of the hollow member.   The freezing method according to claim 2, wherein the hollow member is a sheath pipe.   The freezing method according to claim 2, wherein the hollow member is a casing for drilling a borehole in which the hollow member remains in the ground. The thermally conductive material discharge pipe coated with the heat insulating material is inserted into the hollow member,
The pressure generated by the volume expansion of the frozen heat transfer fluid causes the heat insulating material to be compressed and deformed, and the heat transfer fluid in the region of the hollow member separated from the refrigerant supply side is pressed, and the heat transfer material is discharged through the discharge pipe. The freezing method according to any one of claims 2 to 4, which is discharged out of the hollow member. A borehole extending upward in the vertical direction is drilled, the lower end of the hollow member is closed by a lid, the refrigerant pipe and the heat transfer material discharge pipe pass through the lid, and the heat transfer material discharge pipe is opened and closed. A valve is provided, and the on-off valve is opened if the pressure acting on the lid is larger than the pressure of the heat transfer fluid in the region above the borehole plus the head difference, and closed if less than that Have the ability to
Due to the cold held by the refrigerant flowing through the refrigerant pipe, the heat transfer fluid freezes from the area under the borehole sequentially toward the area above the borehole, and when pressure is generated due to volume expansion, the pressure acting on the lid increases. The freezing method according to any one of claims 2 to 5, wherein the on-off valve is opened and the heat transfer fluid is discharged from the hollow member.

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