JPH06173571A - Method for freezing ground using thermocouple and freezing cylinder - Google Patents

Abstract

PURPOSE:To facilitate control without a need to provide a large scale refrigerator. CONSTITUTION:A module 20 is formed by combining a plurality of thermocouples, each of which comprises two kinds of thermionic elements 11, 12 and has characteristics such that a coupling electrode 14 at the joint of both elements absorbs heat in response to electric current from one of the elements 11, and the electrode 14 of the module 20 is connected to a heat- transfer heat-absorbing board 9 provided in the ground E in electrically insulated relationship. Each thermocouple of the module 20 is connected by means of a connecting electrode 15 and the electrode 15 is attached to the surface of a heat-transfer radiating board 18 in electrically insulated relationship. Electricity is fed to the electrode 14 of the module 20 from one of the elements 11 through the electrode 15 and refrigerant R is caused to flow along the rear side of the board 18 to keep the electrode 15 at a predetermined temperature, so that heat is absorbed from the electrode 14, thereby freezing the ground E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground freezing method and a freezing cylinder using a thermocouple, and particularly to a freezing method, which is a kind of natural ground stabilization treatment in a shield construction method such as tunnel construction, using a thermocouple consisting of a thermoelectric element. The present invention relates to a ground freezing method and a freezing cylinder.

[0002]

2. Description of the Related Art In the conventional freezing method, the following two types of ground cooling methods are used. (1) Direct method: As shown in FIG. 7, the low temperature liquefied gas stored in the liquefied gas tank 30 is sent directly to the freezing pipe 31 which is previously driven into the ground, and the ground E is cooled by the liquefied gas to freeze the ground. F
It is what The liquefied gas is supplied to the liquefied gas tank 30 by, for example, a tank truck 32 or the like. (2) Indirect method: As shown in FIG. 8, for example, a -20 ^o C to -30 ^o C brine B made by a refrigerator is sent to a direct freezing pipe 31 that has been previously driven into the ground, and a low temperature brine B is supplied. At ground E
Is cooled to form a frozen ground F. The refrigerator in the illustrated example includes a compressor 36 for the primary refrigerant R, a condenser 37, and a blower 38 for cooling the water W that cools the condenser 37. The brine B is sent to the brine cooler 34 by the brine pump.
It is sent by 35 and cooled by heat exchange with the primary refrigerant R.

[0003]

However, in the above-mentioned (1) direct method, since the price of liquefied gas is high, not only the construction cost is increased, but also the heat loss during transportation of the liquefied gas is very large, so that the transportation distance is long. However, it is not suitable for long shield work. Also,
In the above-mentioned (2) indirect method, the refrigerator for the primary refrigerant R becomes large in scale, and it may be difficult to secure the installation place as well as the equipment cost. Since the heat loss during the transportation of the primary refrigerant R and the brine B is also very large as in the case of the liquefied gas, there is a problem that the cost of the heat insulation equipment increases when it is used for the construction with a long transportation distance. Furthermore, it is difficult to finely control the ground freezing process in any of the methods, and there is a tendency to increase the equipment scale more than necessary to secure the freezing. Overfreezing
This may prolong the freezing and thawing periods, and at times may cause ground changes such as freezing and subsidence.

Therefore, an object of the present invention is to provide a ground freezing method and a freezing cylinder which do not require a large-scale refrigerator and can be easily controlled.

[0005]

In order to achieve the above object, the present inventor has paid attention to the utilization of the Peltier effect of thermoelectric elements and the recent progress of thermoelectric element materials. Thermocouple 10 illustrated in FIG.
Is composed of two types of thermoelectric elements, for example, an n-type thermoelectric element 11 and a p-type thermoelectric element 12, one end of each thermoelectric element 11, 12 is connected to form a joint portion 13, and the other end of each thermoelectric element 11, 12 is connected. 19 connecting conductor 17
And the other end of each thermoelectric element 11, 12
19 is kept at the same temperature. In the figure, the dotted frame indicates that the two other ends 19 are kept at the same temperature. For example, the current I from one thermoelectric element, which is the n-type thermoelectric element 11, to the coupling portion 13.
When flowing, the temperature of the joint 13 falls below the temperature of the other end 19 of the thermoelectric elements 11, 12 due to the Peltier effect, and the joint 13 absorbs heat. If the two other ends 19 are kept at a constant low temperature, it is possible to lower the joint portion 13 to a temperature lower than the lower temperature and remove more heat from the portion contacting the joint portion 13 to cool it strongly. Figure 6 shows the recently developed bismuth-
For tellurium-based thermoelectric materials, if the two other ends 19, that is, the temperature of the high temperature junction is kept at 0 ^° C, 27 ^° C, 60 ^° C,
3 The report shows that the temperature of the low temperature joint can be lower than that of the high temperature joint by at least about 40 ^° C, about 47 ^° C and about 57 ^° C, respectively. If this principle of the thermoelectric element is used, it can be expected to reduce the scale of the refrigerating equipment for the refrigerant required for ground freezing and facilitate control of the ground freezing process.

Referring to the embodiments shown in FIGS. 1 and 2, the ground freezing method using a thermocouple according to the present invention includes two types of thermoelectric elements 11,
Combining part 13 consisting of 12 and connecting one end of each thermoelectric element 11, 12.
A plurality of thermocouples 10 (FIG. 4) having a characteristic that (the coupling electrode 14 in FIG. 4 and FIG. 1) absorbs heat according to the current from one thermoelectric element, for example, the thermoelectric element 11 are arranged in a predetermined plane shape. To form a module 20 (FIG. 5), and electrically connect the coupling portion 13 of the thermocouple 10 of the module 20 to the heat-conducting heat-absorbing plate 9 provided in the ground E. Vs 10
One thermoelectric element, for example, the other end 19 of the thermoelectric element 11 is connected to the other thermoelectric element of the adjacent thermocouple, for example, the other end 19 of the thermoelectric element 12 by a connection electrode 15, and the connection electrode 15 is electrically insulated and transferred. It is attached to the surface of the heat dissipation plate 18, and current is supplied from the one thermoelectric element to the coupling portion 13 of the thermocouple 10 of the module 20 through the connection electrode 15 and the refrigerant R is provided along the back surface of the heat dissipation plate 18. And the connection electrode 15 is kept at a predetermined temperature to absorb heat from the joint portion 13 to freeze the ground E. Preferably, a bismuth-tellurium-based thermoelectric material or a lead-tellurium-based thermoelectric material is used as the material of the thermocouple 10.

The freezing pipe 1 formed by the thermocouple of the present invention is the ground E
A heat-conductive outer cylinder 22 that can be installed therein, a heat-conductive inner cylinder 23 provided inside the outer cylinder 22, and the inner cylinder 23
The module 20 having the connection electrode 15 electrically insulated and attached to the outer surface of the module 20, and the coolant channel 25 in contact with the inner surface of the inner cylindrical body 23, the thermocouple coupling portion of the module 20. 13 is opposed to the outer cylindrical body 22, and a current I (FIG. 4) is supplied from the one thermoelectric element to the coupling portion 13 of the module 20 through the connection electrode 15 while flowing the refrigerant R in the refrigerant flow path 25. The outer cylinder 22 is formed by the connecting portion 13.
Absorbs heat from. Preferably, the thermocouple coupling portion 13 of the module 20 is brought into electrical contact with the inner surface of the outer tubular body 22. The preferred material for the thermocouple 10 in the module 20 is a bismuth-tellurium-based thermoelectric material or a lead-tellurium-based thermoelectric material.

[0008]

Function: Thermocouple made of bismuth-tellurium thermoelectric material shown in FIG.
The operation will be described with reference to an example using a refrigerant R composed of ice water of 10 and 0 ^° C. However, the present invention is not limited to these thermoelectric materials and refrigerants. After installing the freezing tube 1 of FIG. 1 in the ground E to be frozen as shown in FIG. 2, the refrigerant R of 0 ^° C. is caused to flow in the refrigerant channel 25, and the module 20 is connected through the connection electrode 15.
A current I from, for example, the thermoelectric element 11 is supplied to the coupling portion 13 of. However, the current I from the thermoelectric element 11 causes the coupling portion 13 to absorb heat. Thermoelectric element 1 having the characteristics shown in FIG.
When 1 and 12 are used, theoretically, if the connection electrode 15, that is, the other end 19 of the thermoelectric elements 11 and 12 is kept at 0 ^° C. by the refrigerant R, the joint portion 13 is about −40 ^° C. (= 0− 40) Can be cooled below. Therefore, the ground E can be frozen.

Further, since it is known that the amount of heat absorbed in the joint portion 13 per unit time depends on the current I of the thermocouple 10, the outer cylinder 22 is contacted by adjusting the current I in the joint portion 13. It is expected that the heat absorption rate from the ground E, that is, the ground cooling rate, can be controlled extremely easily within a certain range. Furthermore, if the temperature outside the connection electrode 15 is kept at a temperature lower than 0 ^° C. by a suitable refrigerant R, the temperature of the joint portion 13 can be further lowered. Since a large number of the connecting portions 13 that can be kept at a low temperature are provided so as to face the outer cylindrical body 22, the ground E can be cooled with high efficiency. Moreover, since the temperature of the refrigerant R is not required to be extremely low like liquefied gas, a large-scale refrigerator is not required.

Therefore, the object of the present invention is to provide a "ground freezing method and freezing cylinder which does not require a large-scale refrigerator and is easy to control".

[0011]

In the embodiment shown in FIGS. 1 and 2, the refrigerant R from the refrigerating device 2 of a relatively small scale is sent to the freezing pipe 1 through the supply pipe 3. A downcomer pipe 24 is provided inside the inner tubular body 23 of the freezing pipe 1, and the refrigerant R is first lowered as shown by an arrow D, and then the connection electrode
Heat is radiated from the connection electrode 15 while being raised as indicated by an arrow U along the wall surface to which 15 is attached. The return pipe 7 returns the refrigerant R from the freezing pipe 1 to the refrigeration system 2 and circulates it for use. In the illustrated example, a plurality of connection electrodes 15 are connected to a common heat sink 18
Although it is fixed to the inner cylinder 23 after being attached to the
May be directly attached to the inner cylindrical body 23. Also, the inner cylinder
The fins 8 are projected from the side of the connection electrode 15 in the coolant flow path 25 along 23 to improve the cooling effect of the coolant R on the connection electrode 15.

A required current is supplied from the power source 16 to the module 20 of the freezing tube 1 through the power line 5. Ground E of the outer cylinder 22
A temperature sensor 28 is provided on the contact surface with the temperature sensor 28 and the temperature sensor 28 is provided in the ground E to detect the ground temperature between the adjacent freezing pipes 1.
Properly install the temperature measuring tube 27 with 28. Those temperature sensors
The output of 28 is sent to the control device 4 through the signal line 6.

The operation of the controller 4 will be described with reference to the flow chart of FIG. When the control starts, in step 51, the temperature of the ground E and the surface temperature of the freezing pipe 1 are measured by the information from the temperature sensor 28. In step 52, it is judged whether or not the target freezing distribution control is necessary, and when this control is performed, the required cold heat amount distribution is calculated in step 53 by the numerical simulation based on the information from the temperature sensor 28 to determine the temperature / heat flow distribution of the entire freezing section. Ask as. Next, in step 54, the amount of cooling heat required for ground freezing and the surface temperature of the freezing pipe 1 for that purpose are calculated. Based on the calculation result, in step 55, the temperature of the freezing tube 1 is controlled by controlling the current to the module 20 of the freezing tube 1. If the target freezing distribution control is not performed, the control ends in step 52.
This target freezing distribution control can be easily performed by an appropriate computer.

FIG. 9 shows a thermocouple coupling portion 13 of the module 20.
An example of the structure of the freezing tube 1 in which the outer cylinder 22 is brought into direct contact with is shown.

[0015]

As described in detail above, since the ground freezing method and the freezing cylinder using the thermocouple of the present invention freeze the ground by the refrigerant from the relatively small-scale refrigerating device and the electric current to the thermocouple module. , Has the following remarkable effects. (1) Significant reduction in the scale of refrigeration equipment (2) Significant expansion of the control range of the ground freezing process and improvement of control accuracy (3) Reduction of equipment cost and operation cost of ground freezing equipment (4) Equipment of ground freezing equipment Space reduction (5) Reduction of refrigerant transportation amount and transportation equipment (6) Reduction of heat loss during refrigerant transportation (7) Prevention of excessive freezing of the ground by proper control (8) Reduction of refrigerant transportation amount, thermoelectricity Shortening the freezing and thawing periods by pairwise wide-range temperature control, etc. (9) Preventing ground changes (freezing, subsidence, etc.) by appropriate control (10) Improving the thermal efficiency of the ground freezing process

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a freezing tube according to the present invention.

FIG. 2 is a schematic explanatory view of a ground freezing facility.

FIG. 3 is a control flowchart.

FIG. 4 is a schematic explanatory view of a thermocouple.

FIG. 5 is a schematic explanatory view of a thermocouple module.

FIG. 6 is a graph showing an example of characteristics of a thermocouple.

FIG. 7 is an explanatory diagram of ground freezing by the direct method.

FIG. 8 is an explanatory diagram of ground freezing by the indirect method.

FIG. 9 is a schematic explanatory view of another embodiment of the freezing tube.

[Explanation of symbols]

1 Freezing tube 2 Freezing device 3
Supply pipe 4 Control device 5 Power line 6
Signal line 7 Return pipe 8 Fin 9
Endothermic plate 10 Thermocouple 11 N-type thermoelectric element 12
p-type thermoelectric element 13 coupling part 14 coupling electrode 15
Connection electrode 16 Power supply 17 Connection conductor 18
Heat sink 19 Other end 20 Module 22
Outer cylinder 23 Inner cylinder 24 Downcomer 25
Refrigerant flow path 27 Temperature tube 28 Temperature sensor 30
Liquefied gas tank 31 Direct freezing pipe 32 Tank truck 34
Brine cooler 35 Brine pump 36 Primary refrigerant compressor 37
Condenser 38 blower.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location F25B 25/00 A 8919-3L (72) Inventor Katsuya Ota Katsuya 2-19-1 Tobita, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Center

Claims (5)

[Claims] 1. A plurality of thermocouples, which are composed of two types of thermoelectric elements and have a characteristic that a coupling portion that joins one end of each thermoelectric element absorbs heat according to a current from one thermoelectric element, is arranged in a predetermined plane. To form a module, and electrically couple the thermocouple coupling part of the module to a heat conductive heat absorbing plate provided in the ground, and connect the other end of one thermoelectric element of each thermocouple of the module to the adjacent side. Connected to the other end of the other thermoelectric element of the thermocouple by a connecting electrode, electrically insulating the connecting electrode and attaching it to the surface of the heat conductive heat dissipation plate, and connecting part of the thermocouple of the module via the connecting electrode. The ground by a thermocouple formed by freezing the ground by supplying a current from the one thermoelectric element to the one side and flowing a coolant along the back surface of the heat dissipation plate to absorb heat from the joint while maintaining the connection electrode at a predetermined temperature. Freezing method. 2. The ground freezing method according to claim 1, wherein the thermocouple is made of a bismuth-tellurium thermoelectric material or a lead-tellurium thermoelectric material. 3. A plurality of thermocouples, which are composed of two types of thermoelectric elements and have a characteristic that a coupling portion that joins one end of each thermoelectric element absorbs heat according to a current from one thermoelectric element, is arranged in a predetermined plane shape. Module; a connecting electrode for connecting the other end of one thermoelectric element of each thermocouple of the module to the other end of the other thermoelectric element of an adjacent thermocouple; a heat-conducting outer cylinder that can be installed in the ground; the outer cylinder A heat-conducting inner cylinder provided inside the body, the inner cylinder having an outer surface on which each connection electrode of the module is electrically insulated and attached; and a refrigerant in contact with the inner surface of the inner cylinder. A flow path, the coupling part of the thermocouple of the module is opposed to the outer cylindrical body, the current from the one thermoelectric element to the coupling part of the module through the connection electrode while flowing the refrigerant in the refrigerant flow path. Is supplied by the connecting part A freezing cylinder made of a thermocouple that absorbs heat from the outer cylinder. 4. The freezing cylinder according to claim 3, wherein the coupling parts of the thermocouples of the module are electrically insulated and brought into contact with the inner surface of the outer cylinder, and the outer surface of the outer cylinder is grounded. Freezing cylinder with a thermocouple that can be directly contacted. 5. The freezing cylinder according to claim 3, wherein the thermocouple is made of a bismuth-tellurium thermoelectric material or a lead-tellurium thermoelectric material.