JPS589164Y2 - Shrinkage absorption device for cryogenic piping - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for absorbing shrinkage of cryogenic piping.

In general, piping that circulates cryogenic fluids, such as liquid nitrogen at -196°C, has protective outer tubes placed concentrically around the outer periphery with insulation material, etc., to prevent the cold heat of the cryogenic fluid from being transferred to the outside. This is a configuration that prevents this.

However, since the piping contracts when it receives cold heat from the cryogenic fluid, especially when the piping is installed over a range of several kilometers or more, it is necessary to absorb the amount of cold shrinkage to ensure safety.

Therefore, it was previously proposed to provide a bellows at the center of each unit of piping, for example, about 20 m, and to allow the bellows to absorb the amount of cold shrinkage of the piping.

In this case, if each bellows provided for each unit expands or contracts by the same amount under the same stress, each bellows will equally share the amount of thermal contraction of the entire length of the pipe.

However, if the elastic performance of each of the bellows is uneven, a phenomenon occurs in which a bellows with a comparatively poor performance stretches even when a bellows with a relatively hard performance hardly stretches.

In reality, it is extremely difficult to make each bellows have the same performance, so the latter phenomenon occurs.

For this reason, according to conventional shrinkage absorption means,
There was a drawback that there was a large risk of putting excessive stress on the bellows within a certain unit.

The present invention is a novel invention that improves the conventional drawbacks as described above, and its purpose is to equalize the stress applied to the bellows provided in each unit by a safe and simple means.

Examples will be described in detail below.

FIG. 1 is an explanatory diagram of an apparatus for absorbing the amount of contraction according to an embodiment of the present invention. In the figure, 1 is a pipe having a bellows 2 in the center of a unit having a length l, and 3 is a pipe 1. It is a protective outer tube arranged concentrically in cross section around the outer periphery of the unit and provided with bellows 4 at both ends or one end of the unit.

A heat insulating layer for the pipe 1 is formed by disposing a laminated heat insulating material 6 in the annular space formed by the pipe 1 and the protective outer pipe 3, and making the annular space airtight to form a vacuum section 5.

The pipe 1 having such a heat insulating layer is generally referred to as a heat insulating pipe, and by sequentially combining units of the heat insulating pipe, a heat insulating pipe having a total length of several kilometers can be obtained.

In the present invention, a contraction restricting part 8 is provided at each unit connection part of the entire length of the insulation piping formed by sequentially joining the units of the insulation piping described above to limit the range in which the piping 1 can contract and move.

That is, as shown in FIG. 2, the contraction restriction part 8 includes a protrusion 9 protruding from the outer periphery of the pipe 1, and is provided on both sides of the protrusion 9 so as to limit the axial movement of the protrusion 9 within a predetermined range. It consists of a restraining metal fitting 10 and a heat insulating material 11 provided at the abutting portion between the protrusion 9 and the restraining metal fitting 10.

Although the heat insulating material 11 is fixed to the inner end surface of the restraint fitting 10, within a predetermined range of the restraint fitting 10,
The protrusion 9 moves in the axial direction and comes into contact with the end face position P, P2 of the heat insulating material 11.

However, the end face positions PI and P2 of the heat insulating material 11 limit the expansion and contraction of each bellows 2 in order to prevent the bellows 2 in a certain unit from stretching too much due to the difference in elastic performance of each bellows 2 in adjacent units. It is determined based on the possible position.

Further, as the heat insulating material 11, it is preferable to use a material with good heat insulating properties such as fluororesin or nylon.

In addition, 12 is an outer pipe of the unit joint part that integrates the restraining fitting 10, 13 is an anchor that fixes the end of the entire length of the insulation piping,
7 is a laminated heat insulating material at the unit joint portion.

In the above description, when the cryogenic fluid flows through the passage within the pipe 1, the pipe 1 is contracted by receiving the cold heat of the cryogenic fluid.

Therefore, each bellows 2 expands to absorb the amount of contraction of the entire length of the pipe 1.

However, for example, if the bellows 2 are formed at the center point of the pipe 1 for each unit as shown in Fig. 1, the shrinkage amount J+, which is calculated from the shrinkage AI of the unit unit (unit) of the pipe 1, is indicated by the arrow. It will be added to both ends of each bellows 2,
At this time, if there is no effect of the contraction restriction section 8, which will be described later,
If the bellows 2 of the left unit in FIG. 1 is slightly harder than the bellows 2 of the right unit, only the bellows 2 of the right unit will stretch.

However, since the contraction restriction part 8 is provided at each unit joint, even if the bellows 2 of the left unit is slightly harder than the bellows 2 of the right unit as described above, the piping is connected to the right unit joint. When the protrusion 9 of No. 1 moves to a predetermined position, it comes into contact with the restraining metal fitting 10 and stops.
Bellows 2 of the left unit has no choice but to extend.

Since the contraction limiting portion 8 acts as described above in each unit joint, each bellows 2 almost absorbs the contraction amount Δl within the unit in which it exists. In other words, each bellows 2 substantially equally shares the amount of contraction of the entire length of the pipe 1.

Therefore, there is no need to place an excessive burden on the bellows 2 within a certain unit.

In addition, when the unit length is 1-20 m, the amount of contraction in the pipe 1 cooled to the liquid nitrogen temperature is
．． 3%, i.e. (l = 60 mm).

In addition, since the restraining fitting 10 has a heat insulating material 11 arranged at the part where it contacts the protrusion 9 of the piping 1, t amount of heat is transferred from the outside to the piping 1.
In other words, it is possible to prevent the cold heat of the cryogenic fluid flowing through the passage in the pipe 1 from being transmitted to the outside.

Therefore, vaporization of the cryogenic fluid is prevented, and therefore the piping 1
safety is well maintained.

Further, it is preferable to use the zigzag path of the end bellows 4 of the protective outer tube 3 housed in the outer tube 12 of the unit joint portion and the heat insulating effect of the laminated heat insulating material 7 to further improve the heat insulating effect.

Furthermore, by integrating the protrusion 9 into the end of the piping 1 in advance as shown in FIG. 3, the heat insulating piping unit can be shipped locally. Adjacent units can be easily connected to each other, which is preferable.

In addition, in order to constitute a contraction restriction part that restricts the range in which the piping 1 can contract and move, a restraining fitting 10a that restricts the extension range of the bellows 2 is installed in the bellows 2 part as shown in FIG.
If a bellows 4 is provided at the end of the protective outer tube 3, as shown in FIG. If a restraining fitting 10b is provided at the end in place of the above-mentioned projection 9, the heat insulating effect of the zigzag path of the bellows 4 will deteriorate.

Note that the same reference numerals as in FIG. 1 indicate the same parts.

For this reason, the contraction restricting portion 8 was constructed as explained in FIG. 1.

As explained above, the present invention has a protrusion 9 protruding from the outer periphery of the pipe 1 at the connecting part that connects the units, and a structure on both sides of the protrusion 9 to limit the axial movement of the protrusion 9 within a predetermined range. Since the range in which the piping 1 contracts and moves is restricted by the restraining fittings 10 provided at the bellows 2 along the entire length of the piping 1,
The stress applied to the protrusion 9 can be equalized, and the protrusion 9
Since the heat insulating material 11 is provided at the abutting portion between the pipe and the restraining fitting 10, vaporization of the cryogenic fluid is prevented and the piping is maintained safely.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the shrinkage absorbing device according to the embodiment of the present invention, Fig. 2 is a detailed explanatory diagram of the main parts in Fig. 1, and Fig. 3 is an explanatory diagram of the unit of the insulated piping used in the present invention. , FIG. 4, and FIG. 5 are explanatory diagrams of the positions where the contraction restriction portions are provided. 1 is a pipe, 2 is a bellows for absorbing the amount of shrinkage of the pipe 1, 3 is a protective outer tube, 4 is a bellows of the protective outer tube 3, 5 is a vacuum section, 6 and 7 are laminated insulation materials, 8 is a shrinkage limiting section, 9 1 is a protrusion of the piping 1, 10 is a restraining metal fitting, 11 is a heat insulating material, and 12 is an outer pipe of a unit coupling portion.

Claims (1)

[Scope of utility model registration request] In a shrinkage absorbing device in which a bellows is provided for each unit of piping through which cryogenic fluid flows to absorb the amount of shrinkage of the piping, a protrusion protruding from the outer periphery of the piping is provided at a joint that connects the unit units. a shrinkage restricting part comprising: a restraining metal fitting provided on both sides of the protrusion so as to limit the axial movement of the protrusion within a predetermined range; and a heat insulating material provided at a contact portion between the protrusion and the restraining metal fitting. A shrinkage absorbing device for cryogenic piping, characterized in that it is provided with: