JPH0650234B2 - How to start a thermosiphon for high temperature heat sources - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for starting a thermosiphon intended for a high temperature heat source such as a large-diameter thermosiphon for collecting geothermal heat.

2. Description of the Related Art Conventionally, as a means for collecting geothermal heat, it has been known that water is sent to a high temperature part in the ground and steam generated by energizing the water is taken out from a steam well and used for a predetermined purpose.
However, this type of geothermal extraction facility requires a device that circulates water, a device that separates steam from gravel, and the like, which is a disadvantage in that the facility becomes large. So conventionally,
It has been proposed to use a thermosiphon as a heat collecting means without moving parts. This is a type of heat pipe in which a condensable fluid is enclosed as a working fluid in a vacuum-deaerated closed tube, heat is transported only in the upward direction, and the working fluid condensed in the condensing section is gravitationally applied to the heat source side. The thermosiphon's lower end is inserted into the high temperature part of the ground, and a heat exchange coil etc. is installed at the upper end on the ground side to evaporate the working fluid by the geothermal heat and Is taken out from the heat exchange coil in the form of hot water or the like. And in this kind of equipment, since the part heated by geothermal heat, that is, the evaporation part is wide, a spray pipe is inserted into the closed pipe as a means for returning the working fluid to the evaporation part, and the working fluid in the liquid phase generated in the condensation part. The spray pipe uniformly distributes the liquid on the inner wall surface of the evaporating section so that a dry-out portion does not occur.

In such equipment, since the thermosiphon transfers heat without requiring power, the equipment can be simplified and the control becomes easy.

Problems to be Solved by the Invention In a thermosiphon, when heat collection is stopped in a geothermal extraction facility that uses a thermosiphon that automatically evaporates and flows and condenses a working fluid due to a temperature difference to transfer heat. In order to prevent the working fluid condensed on the upper end side from being collected in an appropriate liquid storage part and be returned to the evaporation part to dry out the evaporation part and to start it again, from the liquid storage part to the spray pipe The working fluid in the liquid phase is sprayed on the inner wall surface of the evaporation portion via the. However, since the temperature of the geothermal heat that is the target of heat collection is high at several hundreds of degrees Celsius, if the evaporation section is dried out to stop heat collection, the inner wall surface of the evaporation section will also become high at several hundred degrees Celsius. As a result, when the working fluid is sprayed on the inner wall surface of the evaporation part to start heat collection, the working fluid cannot wet the inner wall surface, and is repelled as droplets and directly drops to the bottom. In such a state, not only the working fluid does not evaporate sufficiently, but also the temperature of the inner wall surface does not drop, so the high temperature state of the inner wall surface continues forever, and it is not possible to enter a sufficient heat collection state. However, there was a problem in that the response of the heat output at the time of starting was delayed.

The present invention has been made against the background of steam, and an object thereof is to provide a method capable of improving the thermal response at the time of starting when collecting heat from a high temperature portion by a thermosiphon.

Means for Solving the Problems According to the method of the present invention, a closed tube enclosing a working fluid for heat transfer as evaporation latent heat is exposed to a high-temperature heat source to form a vaporization section and its upper end is exposed to the outside. A first liquid return pipe is provided at the center of the closed pipe so that the working fluid condensed by the deprived working fluid vapor can be dispersed on the inner wall surface of the evaporation portion. A high-temperature heat source thermosiphon having a second liquid return pipe that opens a part of the working fluid flowing down along the inner surface of the closed pipe on the inner surface of the closed pipe is used.
The working fluid is caused to flow out from the liquid return pipe to flow along the inner surface of the closed pipe, and then the working liquid is sprayed to the inner surface of the closed pipe from the first liquid return pipe provided inside the closed pipe. It is a method characterized by that.

Effect According to the method of the present invention, even if the inner surface of the evaporation portion of the thermosiphon is dry out and has a high temperature at the time of starting, the supply of the working fluid at this point is such that a liquid film is formed on the inner surface of the closed tube. Since it is performed from the two-liquid return pipe, the inner wall surface is cooled by the falling liquid film, and at the same time, the working fluid is actively evaporated,
The temperature of the inner surface of the evaporating part drops quickly. Then, when the temperature of the inner surface of the evaporating section is lowered, the working liquid is sprayed from the first liquid return pipe, so that the working liquid is uniformly sprayed on the inner wall, and the normal operating state can be quickly reached. Therefore, in the method of the present invention, the hydraulic fluid actively evaporates and transfers heat even immediately after the supply of the hydraulic fluid is started, so that the thermal response becomes good.

Examples Next, the method of the present invention will be described based on Examples.

FIG. 1 is a schematic view showing a thermosiphon 1 for collecting geothermal heat, which is a target of the present invention, in which a lower end portion of a closed pipe 2 is inserted into a high temperature region 3 in the ground to form an evaporation portion 4, Further, its upper end is communicated with a condenser 6 having a built-in heat exchange coil 5, and the condenser 6 has a somewhat large internal volume and serves as a liquid reservoir. A first liquid return pipe 7 is arranged in the central portion of the closed pipe 2 along the axial direction, and a large number of small holes 8 are formed in a lower peripheral wall of the first liquid return pipe 7. The upper end of the first liquid return pipe 7 is connected to the condenser 6 via the first opening / closing valve 9. Further, a second liquid return pipe 11 having a second opening / closing valve 10 interposed is connected to the condensing unit 6, and the second liquid return pipe 11 is located at a position higher than the evaporation unit 4 on the inner surface of the closed pipe 2. It is open to.

A fluid that evaporates and condenses in a target temperature range, such as water and chlorofluorocarbon, is enclosed as a working fluid 12 in the thermosiphon 1 in a state where the inside thereof is vacuum deaerated.

Explaining the method of the present invention for the thermosiphon 1 described above, when the on-off valves 9 and 10 are closed, the working fluid (working fluid) 12 in the liquid phase enters the condensing section 6. In this state, the evaporation section 4 is at a high temperature because there is no working fluid. To start collecting heat, first, the second on-off valve 10 is opened, and the condenser 6
The working liquid 12 therein is fluidized from the second liquid return pipe 11 along the inner surface of the closed pipe 2. Since the working fluid 12 flows down as a liquid film, the working fluid evaporates one after another in the high temperature evaporating section 4, so that the wall temperature of the evaporating section 4 decreases due to the heat being taken by the working fluid. On the other hand, if cold water or the like is allowed to flow through the heat exchange coil 5, the temperature of the condensation section 6 becomes low, so that the working fluid vapor generated in the evaporation section 4 flows to the heat exchange coil 5 after flowing into the condensation section 6. It can be given and condensed, and the heat exchange coil 5 can output heat in the form of hot water or the like. That is, the working fluid 12 transports heat as latent heat of vaporization.

After the working fluid 12 is supplied from the second liquid return pipe 11 as described above, and the wall surface temperature of the evaporator 4 is lowered to some extent, the first opening / closing valve 9 is opened and the second opening / closing valve 10 is opened.
Is closed, and the working liquid 12 is sprayed from the small holes 8 of the first liquid return pipe 7 onto the wall surface of the evaporation unit 4. In this case, since the wall surface temperature is low, the wall surface can be uniformly wetted by the working fluid sprayed on the wall surface, and evaporation easily occurs.

Therefore, if the starting operation is performed according to the procedure described above, the hydraulic fluid 1
The liquid film of No. 2 lowers the wall surface temperature of the evaporating section 4 and actively evaporates the same, and then sprays the working liquid 12 on the wall surface of the evaporating section 4, so that a large amount of steam is generated at the time of startup and the thermal response is high. It improves the sex.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the method of the present invention, when the working fluid is started to be supplied to the evaporation portion in the dry-out state, the wall surface temperature is efficiently lowered, and the sprayed working liquid is droplets. Therefore, the working fluid can be actively vaporized while preventing it from directly falling to the bottom portion, so that a sufficient heat transport amount at the time of starting can be secured and the thermal response can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a thermosiphon targeted by the method of the present invention. 1 ... Thermosiphon, 2 ... Closed tube, 4 ... Evaporator,
5 ... Heat exchange coil, 6 ... Condensing section, 7 ... First liquid return pipe, 9 ... First on-off valve, 10 ... Second on-off valve, 11 ...
Second liquid return pipe, 12 ... Working fluid.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masataka Mochizuki 1-5-1, Kiba, Koto-ku, Tokyo Within Fujikura Electric Wire Co., Ltd. (72) Inventor Koichi Masuko 1-1-5, Kiba, Koto-ku, Tokyo Fujikura Shigeru Kumagai Examiner, Electric Wire Co., Ltd.

Claims (1)

[Claims] 1. A working fluid vapor in which a lower end portion of a closed pipe enclosing a working fluid that transfers heat as evaporation latent heat is exposed to a high-temperature heat source to form an evaporation portion and the upper end portion of the closed pipe removes heat to the outside. A first liquid return pipe is provided at the center of the closed pipe so as to disperse the working fluid condensed in the condensing part on the inner wall surface of the evaporating part, and one of the working fluid condensed in the condensing part. When starting the thermosiphon for high temperature heat source provided with the second liquid return pipe, which is made to flow down along the inner surface of the sealed pipe, on the inner surface of the sealed pipe, the second liquid return pipe is moved along the inner surface of the sealed pipe from the second liquid return pipe. Start of the thermosiphon for high temperature heat source, characterized in that the working fluid of liquid phase is made to flow down to lower the temperature of the inner surface of the evaporation section, and then the working fluid of liquid phase is sprayed from the first liquid return pipe to the inner surface of the evaporation section. Method.