JPS6133358Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a device for preventing freezing of foundation concrete in which a tank for low-temperature liquids such as liquefied natural gas (LNG) and liquefied petroleum gas (LPG) is installed.

Among tanks for storing low-temperature liquids such as LNG and LPG, large industrial tanks 1 are usually constructed by pouring insulating concrete 3 such as perlite concrete on a foundation concrete 2, and installing the tank on top of the insulating concrete 3. However, since the heat insulating effect of the heat insulating concrete 3 is not necessarily sufficient, the foundation concrete 2 may be cooled by the low temperature liquid in the tank 1, and as a result, the foundation concrete 2 may freeze. If such a situation occurs, the strength of the foundation concrete 2 may decrease or cracks may appear in the foundation concrete 2, and as a result, there is a danger that the tank 1 itself may sink downward.
Conventionally, as shown in FIGS. 1 and 2, an electric heater 5 inserted into a protective pipe 4 is buried in the foundation concrete 2, and the electric heater 5 is energized to generate heat, thereby improving the foundation concrete 2. The temperature is kept at around 5℃ to prevent it from freezing.

However, the electric heater 5 has a problem that its mechanical strength is weak and is easily broken, and the electric heater 5 itself is not explosion-proof, so it is especially important for the foundation of the tank 1 containing flammable liquids such as LNG and LPG. In this case, the pipe 4 must be filled with an inert gas such as nitrogen gas to create an explosion-proof structure, which not only complicates the structure but also causes damage to the space between the electric heater 5 and the foundation concrete 2. Since a space is provided between the electric heaters 5 and the electric heater 5 itself having an insulating coating, the total thermal resistance between the electric heaters 5 and the foundation concrete 2 increases, resulting in poor heat transfer coefficient. A problem arose. Furthermore, since the surface area of the electric heater 5 itself is small, if the pipe 4 is made thicker to increase the heat transfer area to the foundation concrete 2, the space interposed between the electric heater 5 and the foundation concrete 2 will become even wider. Therefore, there is a problem that the heat transfer efficiency further deteriorates, and if the pipe 4 is made thinner to solve this problem, the heat transfer area becomes narrower, resulting in the problem of having to increase the number of pipes installed. . Furthermore, the temperature of each part of the electric heater 5 in its length direction is not necessarily uniform, so localized low-temperature and high-temperature areas occur, and especially in the center of the foundation concrete 2, the surrounding area is exposed to heat from the atmosphere. However, since there is no natural inflow of heat from the outside, it is easy to cool down, and as a result, the conventional equipment described above cannot uniformly heat and keep the foundation concrete 2 warm. In the worst case scenario, there was a risk that cracks would occur in the foundation concrete 2 and that this would lead to further losses.

This idea was devised to solve the above problems; the overall structure is simple and explosion-proof, the entire base of the tank can be heated evenly, and it is durable. The purpose of this invention is to provide a basic antifreeze device for cryogenic liquid tanks that has excellent reliability.

Embodiments of this invention will be described below with reference to FIGS. 3 to 5.

FIG. 3 is a schematic cross-sectional view showing one embodiment of this invention, and FIG.
are installed on the foundation concrete 12 with the insulation concrete 11 in between. The foundation concrete 12 is formed into a short cylindrical shape with a larger diameter than the tank 10, and inside it, more precisely on the upper side, a plurality of heat pipes 13 are installed so that one end protrudes outside the foundation concrete 12. They are buried horizontally so that they are parallel to each other. The heat pipe 13
The exterior body is a corrugated pipe, and one of them is shown in Figure 5.
As shown in the figure, the pitch p of the corrugated pipe waves is
The heat pipe 13 is set to be small at the center corresponding to the center of the foundation concrete 12, and as a result, the heat radiation area of the heat pipe 13 is wide at the center in the longitudinal direction. One end of each heat pipe 13 protrudes from the foundation concrete 12, and the end is immersed in a hot water tank 14 disposed adjacent to the foundation concrete 12. The hot water tank 14 is a heating source for the foundation concrete 12.
4, hot water (e.g. 5°C to 40°C) higher than the temperature of the foundation concrete 12 to be maintained (e.g. about 5°C) is added.
°C) is circulated and supplied from a hot water boiler 15 via a pump 16. Therefore each heat pipe 1
3, the part immersed in the hot water bath 14 serves as a heating part (evaporation part), and the part buried in the foundation concrete 12 serves as a heat dissipation part (condensation part).

However, in the antifreezing device configured as described above, since there is a temperature difference between the foundation concrete 12 and the hot water, the heat pipe 13 transports the heat of the hot water into the foundation concrete 12, and as a result, the foundation concrete 12 is heated It can be heated and kept warm by the heat it has. In that case, as described above, the heat pipe 13 has a configuration in which the wave pitch p of the corrugated pipe that is the exterior body is set small at the center, so that the center of the foundation concrete 12 is relatively easily cooled. The amount of heat dissipated from the heat pipe 13 increases, so in the above device,
By appropriately controlling the temperature of the hot water in the hot water tank 14, the heat pipe 13 itself has the property of equalizing the temperature, and the foundation concrete 12
It is possible to uniformly heat and keep the whole body warm at, for example, about 5°C and prevent it from freezing. Furthermore, the heat pipe 13 does not have a high temperature part that would cause the liquid in the tank 10 to ignite, and since the heat pipe 13 itself has an explosion-proof structure, it does not require special explosion-proof treatment as in the case of using a conventional electric heater. Furthermore, since the heat pipe 13 has high strength and has no moving parts, it does not necessarily require a protective tube such as a conventional pipe, and can provide a highly reliable antifreeze device. Furthermore, since the entire outer peripheral surface of the heat pipe 13 is a heat dissipation surface, the heat transfer area for each heat pipe 13 to the foundation concrete 12 is large. The number of electric heaters can be significantly reduced compared to the number of electric heaters.

In addition, to prevent freezing, the foundation concrete 12
Hot water as a heat source for heating is 5°C to 40°C.
℃ or so, river water or seawater may be used as the hot water depending on the surrounding situation of the location where the tank 10 is set. Also, as a heating device for obtaining hot water, a hot water boiler may be used. Alternatively, a solar collector may be used. Furthermore, in this invention, a configuration may be adopted in which geothermal heat is used instead of hot water as a heat source for heating the foundation concrete 12.

As is clear from the above explanation, according to this invention, the exterior body of the heat pipe buried in the foundation concrete is made of a corrugated pipe, and the pitch of the corrugated waves is made smaller at a location corresponding to the center of the foundation concrete. In addition, one end of the heat pipe is made to protrude outside of the concrete, and the protruding end is placed in a heating source, and the heat of the heating source is transported into the foundation concrete by the heat pipe. Since freezing is prevented, the heat dissipation area of the heat pipe becomes larger in the center of the foundation concrete, where it is relatively difficult to heat and retain heat, or in other words, in the center where it is easier to cool than other parts, and therefore the heat Coupled with the fact that the pipe itself has the property of equalizing the temperature, it is possible to uniformly heat and maintain the temperature of the entire foundation concrete. In addition, since the heat pipe itself has a so-called explosion-proof structure, there is no need for special explosion-proof treatment even if liquefied fuel such as LNG is stored in the tank, and the heat pipe is strong and movable. Since there are no parts, it is possible to obtain a freeze prevention device that has a simple structure and is highly reliable in terms of durability. Furthermore, the entire outer circumferential surface of a heat pipe is a heat dissipation surface, and the heat transfer area between each heat pipe and the foundation concrete is large, so the number of heat pipes can be reduced, which also simplifies the structure. can be made into something.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing an example of a conventional device, Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, Fig. 3 is a schematic cross-sectional view showing an embodiment of this invention, and Fig. 4 is a 3
FIG. 5 is a sectional view taken along the - line in the figure, and a front view showing an example of the heat pipe used in this invention. 10...Tank, 12...Foundation concrete,
13...heat pipe, 14...tank, p...
Pitch (of corrugated pipe).

Claims (1)

[Scope of utility model registration request] Multiple heat pipes with corrugated pipes as exterior bodies are buried almost horizontally and parallel to each other in the foundation concrete in which a low-temperature liquid tank is installed. The pitch of the waves of the corrugated pipe is set small, and one end of the heat pipe is made to protrude in the same direction from the foundation concrete, and the end is provided adjacent to the foundation concrete and is a heating source having a temperature higher than the holding temperature of the foundation concrete. A basic freeze prevention device for a low temperature liquid tank, characterized in that it is arranged in a.