JP2602803B2 - Heat pipe laying method of heat pipe type geothermal extraction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geothermal extraction apparatus for pumping geothermal heat to the ground by means of a heat pipe, and more particularly to a method for inserting and laying the heat pipe in a so-called shaft.

[0002]

2. Description of the Related Art As is well known, a heat pipe is obtained by sealing a condensable fluid such as water, alcohol, or chlorofluorocarbon as a working fluid in a container such as a pipe that has been degassed under vacuum, and a temperature difference occurs. In this way, the working fluid evaporated in the high-temperature portion flows to the low-temperature portion to radiate and condense, thereby performing heat transport as latent heat of the working fluid. In this way, heat pipes operate due to a temperature difference, and their apparent thermal conductivity reaches tens to hundreds of times that of metals such as copper. Has been adopted.

[0003] As one example, conventionally, high-temperature geothermal heat is extracted on the ground by a heat pipe, and the heat is effectively used for snow melting, power generation, and the like. This type of heat pipe type geothermal extraction device has a configuration in which one end of a heat pipe is inserted and hung in a digging hole dug toward the terrain several hundred meters underground, and the geothermal heat is generated at the lower end of the container. The heated working fluid flows to the end on the ground side and radiates heat, so that only geothermal heat can be pumped up without including foreign substances such as gravel.

[0004] By the way, this type of heat pipe is a long one having a length of several hundred meters and its weight is considerably heavy. Therefore, it can withstand its own weight if it is hung in an excavation hole as it is. It must be difficult to design and manufacture, such as increasing the wall thickness.

An example of a means for supporting the weight of the heat pipe when suspending the long heat pipe toward the ground is described in Japanese Patent Publication No. 5-4945. The structure described in this publication will be briefly described with reference to FIG. 2 and FIG. 3. Two ropes 2 are hung on the outer side surface of the corrugated heat pipe 1 along its length direction. Has been lowered. The rope 2 is, for example, a stranded wire of steel or the like, the upper end of which is locked by a fixed pedestal (not shown) on the ground, and the lower end of which is a terminal fitting 3 for holding the lower end of the heat pipe 1. Etc. are fixed. The outer periphery of the heat pipe 1 is fastened together with the rope 2 at predetermined intervals in the length direction (for example, at intervals of 5 m) by the hinged band-shaped member 4. In this way, by causing the weight of the heat pipe to bear on the rope or the like, a breakage accident due to the extension of the heat pipe is prevented.

A method of utilizing buoyancy when a long material is drawn into a pipe is known.
-55507. This method is a method in which a cable such as water or oil is injected into the conduit after the cable is inserted into the conduit, and the cable is drawn into the conduit with the conduit in that state. Therefore, the cable to be drawn in is separated from the existing cable by buoyancy and lubricated by the liquid, so that the cable is easily drawn in.

[0007]

However, as described above, since the heat pipe 1 used for extracting geothermal heat is a long one having a length of several hundreds of meters, the conventional technique does not use a heat pipe. It is necessary to prepare a considerably long body 2 as well, and the work of assembling this to the heat pipe 1 with the hinged band-shaped member 4 or the like becomes large. In addition, when the heat pipe 1 is lowered into the shaft, it is necessary to work out the rope body in accordance with the lowering of the heat pipe and to fasten the heat pipe to the heat pipe. Was.

On the other hand, the method described in Japanese Patent Application Laid-Open No. 2-55507 is a method that utilizes buoyancy when a cable is drawn into a pipeline. Therefore, this cannot be immediately diverted as a method for laying long heat pipes, that is, when laying heat pipes in vertical shafts, it is necessary to suspend the heat pipes, This is because there are conditions completely different from the cable laying such as that the lower end is closed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat pipe laying method for a heat pipe type geothermal extraction apparatus in which heat pipes can be easily laid.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a heat pipe for extracting geothermal heat for transporting heat as latent heat into a digging hole formed downward in the ground. In inserting the evaporator, a water-tight casing pipe is fitted into the excavation hole, and the heat pipe is filled with a buoyancy generating medium for applying buoyancy to the heat pipe inside the casing pipe. It is characterized by being hung and inserted into a casing tube.

Further, according to the present invention, the amount of the buoyancy generating medium can be adjusted according to the insertion depth of the heat pipe.

[0012]

In the present invention, first, a casing tube is fitted into a previously formed excavation hole, and a predetermined amount of a buoyancy generating medium is injected into the casing tube. In addition, since the watertightness of the casing tube is ensured, there is no possibility that the buoyancy generating medium leaks into the ground, and the whole injected amount is stored in the casing tube. Next, the operation is completed by sequentially inserting a heat pipe into the casing tube from the end serving as the evaporating portion to a predetermined depth. Since the weight of the heat pipe is reduced by the buoyancy, the heat pipe is laid in the casing pipe in a favorable state in which the heat pipe does not extend.

In addition, when the heat pipe is inserted into the casing pipe and the amount of the buoyancy generating medium stored in the casing pipe is adjusted according to the insertion depth of the heat pipe, the buoyancy generating medium is reduced. Inconveniences such as overflowing from the casing tube or inability to sufficiently hold the heat pipe are prevented beforehand, and the heat pipe can be inserted more smoothly.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example in which a heat pipe type geothermal extraction device according to the present invention is configured to be used for power generation. An excavation hole 6 of several hundred meters is dug almost vertically from the ground to the underground hot rock 5, and a bottomed cylindrical casing pipe 7 is formed in the excavation hole 6 at the bottom thereof. , That is, it is tightly fitted with the opening side facing upward. The casing pipe 7 improves the strength of the excavation hole 6 against the pressure of the ground,
This is to prevent the collapse, and specifically, a steel pipe is preferable in terms of strength, but a copper pipe or the like is used particularly when giving priority to thermal conductivity. Further, in order to completely prevent leakage of the injected buoyancy generating medium 8, watertightness is ensured. And inside the casing tube 7,
One end of a heat pipe 9 slightly smaller in outer diameter than the casing pipe 7, that is, a steam pipe 10 is inserted from the ground side.

On the other hand, an injection / discharge means 11 is provided near the heat pipe 9 on the ground. This injection and discharge means 1
1 includes, as an example, a tank 12 for temporarily storing the buoyancy generating medium 8 and a pipe 13 communicating with the tank 12, and a pump 15 and a valve 16 are provided in the pipe 13. I have. The open end of the conduit 13 is inserted between the steam pipe 10 and the casing pipe 7 so that the buoyancy generating medium 8 can be arbitrarily injected and discharged between them. In addition, as the buoyancy generating medium 8,
Any material that generates buoyancy in the steam tube 10 may be used, but preferably has good thermal conductivity and does not corrode the steam tube 10 and the casing tube 7. One example is water.

A relief valve 2 is provided in the casing tube 7 above the liquid level of the buoyancy generating medium 8 to be injected.
4 with a buoyancy generating medium 8
It is configured to be able to discharge steam and the like generated from the outside to the outside.

A condenser 17 is attached to an end of the steam pipe 10 extending to the ground. The condenser 17 is connected to a return pipe 19 in which a flow control valve 18 is provided. The return pipe 19 is inserted into the steam pipe 10 in the middle thereof, and the liquid-phase working fluid A is supplied to the evaporating section 20 at the lower end of the steam pipe 10.
To communicate. That is, a closed circulation path is formed as a whole, and a fluid such as water or alcohol which evaporates and condenses at a target temperature is sealed as a working fluid A in a vacuum degassed state inside the circulation path, and a loop type heat It is a pipe 9.

The condenser 17 is connected to a power generator 23 via a pipe 22 in which a pump 21 is provided. That is, water is evaporated by the heat that the working fluid A transports to the condenser 17, and the water vapor is supplied to the power generator 23. Although not shown, the heat pipe 9 is fixed to the ground surface by an appropriate means.

Next, an example of a procedure for laying a steam pipe on a casing pipe in the geothermal extraction apparatus configured as described above will be described. First, the casing pipe 7 is buried in the already formed excavation hole 6. In this case, it is carried out by construction equipment according to a common law. Next, the injection / discharge means 11 is operated to inject an appropriate amount of the buoyancy generating medium 8 into the casing tube 7 and, at the same time, the steam pipe 10 is inserted. That is, by opening the valve 16, the tank 1
The buoyancy generating medium 8 in 2 flows down the pipe 14 and is supplied to the casing pipe 7. In this case, the amount of the buoyancy generating medium 8 to be injected, in other words, the water level in the casing pipe 7 does not apply excessive pressure to the steam pipe 10 and the length of the inserted steam pipe 10 into the casing pipe 7 Adjusted to the corresponding amount.

Further, the steam pipe 10 is inserted so as to be sequentially sent out from the tip portion. In this case as well, construction equipment according to the ordinary law is used. Here, if the amount of the buoyancy generating medium 8 is excessive or insufficient, the valve 16 and the pump 15 are finely adjusted to complete all operations. By the buoyancy acting on the steam pipe 10, the steam pipe 10 is suspended and held in the casing pipe 7 in a favorable state with its own weight reduced.

As described above, the injection of the buoyancy generating medium is very easily performed on the ground by the valve and the pump, and the operation of inserting the steam pipe into the casing pipe is practically impossible.
Since it is simply inserted as it is and does not require cumbersome assembling work or special construction equipment in each of the above-described steps, the labor for inserting and laying the steam pipe can be greatly reduced.

Next, the operation of the geothermal extraction will be described. When the flow control valve 18 is opened to a predetermined opening, the condenser 1
The working fluid A in the liquid phase stored in 7 flows down inside the return pipe 19 due to its own weight and flows into the inner bottom of the steam pipe 10. The steam pipe 10 is exposed to high-temperature geothermal heat through the casing pipe 7, and the temperature of the vicinity of the condenser 17 on the ground side is low. Flow into 17. Then, the working fluid vapor A is deprived of heat and condenses. Thus, the condenser 1
Water is warmed by the heat collected in 7 and evaporates. Then, the water vapor is guided to the power generation device 23 through the pipe 22 and used for power generation. The working fluid A liquefied inside the condenser 17 passes through the return pipe 19 and is re-evaporated.
1 and heated to vapor, and thereafter the same cycle is continued until the flow control valve 18 is fully closed.
Further, as described above, since the buoyancy generating medium 8 is selected to have excellent thermal conductivity, the geothermal extraction efficiency is improved as compared with the case where there is a space between the casing pipe 7 and the steam pipe 10. There are also benefits.

In the above embodiment, the heat extracted by using a so-called loop type heat pipe is used for power generation. However, the present invention is not limited to the above embodiment. The pipe may be a single pipe type, or may be configured to use the extracted heat for melting snow. Furthermore, a steam pipe is inserted into a casing pipe in which a buoyancy generating medium is stored in advance, and the steam pipe is supported by buoyancy, and the steam pipe is lowered into the casing pipe by lowering the water level of the buoyancy generating medium from that state, and It may be held.

[0024]

As described above, according to the present invention, when inserting a heat pipe for geothermal extraction into a drilling hole, a watertight casing pipe is fitted into the drilling hole, and a heat pipe is inserted therein. The work is completed by suspending and inserting the heat pipe into the casing pipe with the buoyancy generating medium that exerts buoyancy injected, and the heat pipe can be laid well, so the heat pipe is placed in the shaft. A series of operations up to laying can be greatly saved. That is, the laying operation is simplified.

Further, if the amount of the buoyancy generating medium to be injected is adjusted according to the insertion depth of the heat pipe, the insertion amount of the heat pipe into the casing pipe can be adjusted by the amount of the buoyancy generating medium. Can be performed more easily.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a conventional technique.

FIG. 3 is a sectional view taken along line II-II of FIG. 2;

[Explanation of symbols]

5 ... rock, 6 ... drilling hole, 7 ... casing tube, 8 ...
Buoyancy generating medium, 9: heat pipe, 11: injection / discharge means, 20: evaporator.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mikiyuki Ono 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Masataka Mochizuki 1-5-1 Kiba, Koto-ku, Tokyo Co., Ltd. Inside Fujikura (72) Inventor Yuji Saito 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. 56) References JP-A-7-280361 (JP, A) JP-A-7-286760 (JP, A)

Claims (2)

(57) [Claims] 1. A watertight casing is inserted into a drilling hole formed in a ground and formed in a downward direction into a drilling hole of a heat pipe for extracting geothermal heat for transporting heat as latent heat. A heat pipe type wherein the heat pipe is suspended and inserted into the casing pipe while a buoyancy generating medium for applying buoyancy to the heat pipe is injected into the casing pipe while fitting the pipe. A method of laying a heat pipe of a geothermal extraction device. 2. The method according to claim 1, wherein the amount of the buoyancy generating medium is adjusted according to the insertion depth of the heat pipe.
The heat pipe laying method of the heat pipe type geothermal extraction device according to the above.