JP7489212B2 - Metallic insulation equipment - Google Patents

Description

The present invention relates to a metal-coated insulation device.

Conventionally, in order to insulate and keep warm objects having a cylindrical outer peripheral surface, such as pipes and tanks in nuclear power generation facilities, experimental nuclear reactors, and various other nuclear-related facilities, there has been a metal-coated insulation device in which a box-shaped partial cylindrical metal casing with a curved surface that follows the cylindrical outer peripheral surface is provided and can be arranged in multiple units along the cylindrical outer peripheral surface of the object to be insulated having a cylindrical outer peripheral surface, and an insulating material is housed within the partial cylindrical metal casing.
One type of insulation material is one in which multiple sheets of metal foil embossed with an uneven shape are stacked and housed inside a partial cylindrical metal casing.However, this has the disadvantage that the metal foils are in contact with each other at many points, resulting in high thermal conductivity and a large amount of heat loss.
In response to this, a metal-coated thermal insulation device has been proposed in which either a metal foil or an inorganic fiber sheet is corrugated and bonded to each other, and the composite sheet is housed in a metal casing (see, for example, Patent Document 1).

Japanese Utility Model Application Publication No. 7-41192

In the above-mentioned conventional composite sheets combining metal foil and an inorganic fiber sheet, when the corrugated sheet is made of metal and the flat sheet is made of an inorganic fiber sheet, the tensile strength of the inorganic fiber sheet is weaker than that of a metal sheet, increasing the possibility of breakage during production, etc., and furthermore, the flat inorganic fiber sheet has a low thermal reflectivity, so it is not effective in blocking radiant heat when the object to be insulated is at a high temperature.
Furthermore, when the corrugated sheet is an inorganic fiber sheet and the flat sheet is made of metal, not only is it difficult to mold the inorganic fiber sheet, but even if it is molded, its elasticity is low. It is possible to increase the thickness to maintain the space and thus increase the elasticity slightly, or to impart adhesive thereto, but this not only causes an increase in weight but also poses problems with durability at high temperatures.
In other words, the strength before bonding decreases due to thermal decomposition under high temperatures, and the inorganic fibers become brittle with long-term use, making them more susceptible to dust generation, and the function of securing space may be reduced.
Therefore, if the number of laminated composite sheets increases, the load of the multiple metal flat sheets makes it difficult to maintain equal spacing between the flat sheets, which poses the problem of making it difficult to maintain equal insulation performance of the insulation material.

Therefore, in order to solve the above-mentioned problems, the applicant of the present application has proposed in Patent Application No. 2012-200190 (JP Patent Publication No. 2014-55622), a metal-coated insulation device in which, as the insulation material, a plurality of metal flat plates aligned along the curved surface within the partial cylindrical metal casing are stacked in the heat transfer direction, and metal strip-shaped spacing members are arranged along the curvature direction of the curved surface between each of the plurality of metal flat plates and at least two locations in the longitudinal direction of the partial cylindrical metal casing, forming spaces between adjacent metal flat plates in the heat transfer direction and between adjacent strip-shaped spacing members in the longitudinal direction of the partial cylindrical metal casing, and the surfaces of the metal flat plates are formed into a mirror or approximately mirror finish.
In the above-mentioned metal-coated insulation device, the multiple metal flat plates along the curved surface and stacked in the heat transfer direction within the partial cylindrical metal casing each have shape that follows the curved surface, so they have shape retention and are less likely to deform. Therefore, by simply arranging metal strip-shaped spacing members along the curvature direction of the curved surface between each of the multiple metal flat plates and at least two locations in the longitudinal direction of the partial cylindrical metal casing, without having to arrange them over the entire surface of the metal flat plates, the spacing between the metal flat plates can be maintained even over almost the entire surface, and space for insulation can be reliably secured between adjacent metal flat plates in the heat transfer direction and between adjacent strip-shaped spacing members in the longitudinal direction of the partial cylindrical metal casing. Moreover, the contact area between the metal flat plates and the strip-shaped spacing members is small, so that contact thermal conduction can be kept low and excellent insulation performance can be expected.
Furthermore, the strip-shaped spacing members use less metal material than flat metal plates, making them easier to manufacture and lighter in weight, and because they are made of the same metal as the flat metal plates, they are easy to clean, and the height of the strip-shaped spacing members can be set to a height that makes it difficult for internal air to convect in the spaces between the metal plates and in the spaces formed by the side plates of the metal casing, thereby maintaining high thermal insulation performance. Moreover, the flat metal plates and the strip-shaped spacing members can be fixed together by spot welding or the like without using adhesive.
Furthermore, the curved metal plate that fits the cylindrical outer periphery of the object to be insulated has an excellent effect of blocking heat radiation from the object to be insulated. In other words, the heat rays radiated from the object to be insulated are reflected toward the object to be insulated without being diffused, as compared to the corrugated metal plate surface, and the radiant heat is not allowed to escape to the outside.
Furthermore, a metal plate having a mirror-like or nearly mirror-like surface can reflect more radiant heat from the object to be insulated due to its excellent surface reflectivity, preventing heat leakage to the outside or heat from entering from the outside, thereby improving the radiation insulation performance.
Furthermore, the metal belt-shaped spacer has a greater elastic resilience than the inorganic fiber sheet and is therefore superior in its space-retaining function.
Therefore, it is possible to obtain the effect that a heat insulating material with uniform heat insulating performance can be accommodated within the partial cylindrical metal casing.
However, when increasing the number of metal flat plates to further improve the insulation performance in the heat transfer direction and thereby increase the radiation insulation performance, there is a problem in that there is a limit to how much the spacing between the adjacent metal flat plates can be reduced when using metal strip-shaped spacing retainers.

The object of the present invention is therefore to provide a metal-coated thermal insulation device that solves the above problems and further improves the function of reducing radiant heat and securing space within a partial cylindrical metal casing.

The first characteristic of the present invention is a metal-coated insulation device that can be arranged along a cylindrical outer peripheral surface of an object to be insulated, and that has a box-shaped partial cylindrical metal casing with a curved surface along the cylindrical outer peripheral surface, and that contains an insulation material inside the partial cylindrical metal casing. As the insulation material, a plurality of metal flat plates along the curved surface are stacked in the heat transmission direction inside the partial cylindrical metal casing, and metal wire rods of uniform thickness are arranged separately between each of the plurality of metal flat plates and at least two locations in the longitudinal direction of the partial cylindrical metal casing, in a state where they are wound along the curved direction from one end to the other end in the curved direction of the curved surface, forming a space between adjacent metal flat plates in the heat transmission direction and between adjacent wire rods in the longitudinal direction of the partial cylindrical metal casing, and the surface of the metal flat plate is formed into a mirror or nearly mirror heat ray reflecting surface.

According to the first characteristic configuration of the present invention, by simply arranging metal wires of uniform thickness over the entire length, wound along the curvature direction from one end to the other end of the curved surface in the curvature direction, at intervals between each of the multiple metal flat plates stacked in the heat transfer direction, and at least two locations in the longitudinal direction of the partial cylindrical metal casing, between each of the multiple metal flat plates stacked in the heat transfer direction, and even if not arranged over the entire surface of the metal flat plates, the intervals between the metal flat plates can be maintained uniform over almost the entire surface, and space for insulation can be reliably secured between adjacent metal flat plates in the heat transfer direction and between adjacent wires in the longitudinal direction of the partial cylindrical metal casing.
Furthermore, since the spacing between these metal plates is determined by the thickness of the wire, it can be set much more simply and accurately than in the prior application, when the spacing between the metal plates is set by processing a strip-shaped spacing material, and assembly is simplified, improving production efficiency.
Moreover, since the spacing between the metal flat plates is determined by the thickness of the wire, a larger number of metal flat plates can be stacked in the storage space in the partially cylindrical metal casing than when the strip-shaped spacing material of the prior application is used. Metal flat plates having a mirror or nearly mirror-like heat ray reflecting surface have excellent surface reflectivity, which allows them to reflect more radiant heat from the object to be insulated, preventing heat leakage to the outside or heat penetration from the outside, thereby improving the radiation insulation performance. This radiation insulation performance increases in proportion to the number of metal flat plates. Therefore, by increasing the number of metal flat plates as described above, the radiation insulation performance can be further improved.

The second characteristic feature of the present invention is that, in the multiple wire rods arranged between the multiple stacked metal plates, adjacent wire rods in the heat transfer direction with the metal plates sandwiched between them are arranged at different offset positions in the longitudinal direction of the partial cylindrical metal casing.

According to the second characteristic configuration of the present invention, in addition to being able to achieve the above-mentioned effects of the first characteristic configuration of the present invention, the multiple wires are not arranged at the same position in the longitudinal direction of the partial cylindrical metal casing, but are arranged at different positions offset in the longitudinal direction of the partial cylindrical metal casing, so that the heat transfer path becomes longer in the heat transfer from the object to be insulated, and the heat transfer resistance becomes larger. As a result, the insulating performance of the metal-coated insulation device is improved.

The third characteristic feature of the present invention is that the metal plate and the wire are made of the same type of metal.

According to the third characteristic configuration of the present invention, the metal plate and the wire are made of the same metal, which suppresses the generation of potential differences due to contact, thereby suppressing the occurrence of electrolytic corrosion, and as a result, the device can be installed and used for a long period of time.

FIG. 2 is a partially cutaway perspective view of the metal-coated insulation device of the present invention before it is installed on an object to be insulated. 1 is a cross-sectional view of a metallized insulation device of the present invention; 1 is a graph showing the change in thermal conductivity with the change in the number of metal flat plates when the insulation thickness of the insulation device is constant. 1A and 1B are cross-sectional views of a metal-coated thermal insulation device in Experimental Example 1, in which (a) shows a part of a horizontal cross section, and (b) is a longitudinal cross section along the longitudinal direction. 11 is a graph showing a comparative change in thermal conductivity with intermediate temperature change compared to a conventional product in Experimental Example 2. 13 is a graph showing the change in thermal conductivity with respect to the conventional product in accordance with the change in the insulation thickness of the insulation device in Experimental Example 3.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
For example, in order to insulate and keep warm an object 6 having a cylindrical outer peripheral surface, such as piping or a cylindrical tank-type pressure vessel in a nuclear power plant, an experimental nuclear reactor, or other various nuclear power-related facilities, and to enable replacement work to be performed in a short time to minimize radiation exposure, a box-shaped partially cylindrical metal casing 2 having a curved surface 1 along the outer peripheral surface is provided for the object 6 having a cylindrical outer peripheral surface, as shown in Figures 1 and 2. The box-shaped partially cylindrical metal casing 2 can be arranged in plurality along the cylindrical outer peripheral surface, and has a curved surface 1 along the outer peripheral surface. A plurality of stainless steel foils (S US) flat metal plates 3 are stacked in the heat transfer direction, and stainless steel (SUS) wires 4 are arranged between each of the flat metal plates 3 and at two locations, at both ends or near both ends in the longitudinal direction of the partial cylindrical metal casing 2, along the curvature direction of the curved surface 1. Spaces S are formed between adjacent flat metal plates 3 in the heat transfer direction and between adjacent wires 4 in the longitudinal direction of the partial cylindrical metal casing 2, and the surfaces of the flat metal plates 3 are formed into mirror or nearly mirror finishes (heat ray reflecting surfaces) and are housed within the partial cylindrical metal casing to form a metal-coated thermal insulation device.

By placing multiple wires 4 between each of the multiple stacked metal flat plates 3, the heat transfer path becomes longer in the heat transfer phenomenon from the object to be insulated 6 and from the outside to the object to be insulated 6, and the heat transfer resistance becomes larger, thereby improving the insulating performance of the metal-coated insulation device.

The partial cylindrical metal casing 2 is made of stainless steel (SUS) and is formed into a semi-cylindrical shape split into two when the object to be insulated 6 is a fluid pipe (sometimes split into three or more parts in the circumferential direction), and when it is a tank or the like, is formed into a cross section that is split into many parts in the circumferential direction of the tank, and multiple partial cylindrical metal casings 2 are assembled and adjacent ones are connected together with connecting members such as buckles 5 installed at the ends, so that the entire circumference of the object to be insulated 6 can be insulated.

The metal flat plate 3 is made of stainless steel and has a thickness of 0.03 mm to 0.3 mm, and has a mirror or nearly mirror-finished surface. It is formed into a partial cylindrical shape to fit the curved surface 1 of the partial cylindrical metal casing 2, thereby giving the metal flat plate 3 its own shape retention while increasing its reflectance against radiant heat from the object to be insulated 6.
The wires 4 and the flat metal plates 3 are not bonded together and are stacked in the direction of the radius of curvature of the curved surface 1. As shown in Fig. 4(b) , the wires 4 arranged between the stacked flat metal plates 3 are shifted to different positions in the longitudinal direction of the partial cylindrical metal casing 2.

[Experimental Example 1]
Next, in a flat-plate-shaped heat insulating device having the same structure as that shown in FIG. 4B, the distance between the metal plates was changed to create different numbers of metal plates 3, and the change in thermal conductivity was measured.
The thickness of the metal insulation material was fixed at 29 mm, and the wire rod 4 used to keep the distance between the metal plates was made of stainless steel wire (SUS) with a thickness of 2 mm. The number of wires stacked in the heat transfer direction was changed to change the distance between the metal plates. The metal plate 3 was made of stainless steel foil (SUS) with a thickness of 50 μm.
As a result, as shown in the graph of FIG. 3, it is clear that as the number of metal plates 3 increases, the thermal conductivity (W/mK) decreases.

[Experimental Example 2]
Next, the thermal conductivity was measured using a cylindrical insulation device having the same structure as that shown in Fig. 4(b) and compared with a conventional product. Note that a metal insulation material with a constant insulation thickness of 50 mm and a structure similar to that of Experimental Example 1 was used.
As a result, as shown in the graph of FIG. 5, it was confirmed that the thermal conductivity at the intermediate temperature of 170° C. was reduced by about 20% compared to the conventional product.

[Experimental Example 3]
Next, the thermal conductivity was measured using a cylindrical insulation device with the same structure as in Fig. 4(b) and compared with a conventional product. Note that a metal insulation material with a constant insulation thickness of 50 mm and 100 mm and a structure similar to that of Experimental Example 1 was used.
As a result, as shown in the graph in Figure 6, it was confirmed that at an intermediate temperature of 170°C, the thermal conductivity decreased by approximately 20% compared to the conventional product, regardless of whether the insulation thickness was 50 mm or 100 mm. It is clear from Figure 6 that the rate of decrease in thermal conductivity is greater for a thickness of 100 mm than for a thickness of 50 mm.

[Another embodiment]
Other embodiments will be described below.
<1> The wire rods 4 may be disposed at an intermediate portion between the two ends or near the two ends in the longitudinal direction of the partial cylindrical metal casing 2, or may be disposed at three or more locations in total. In other words, it is sufficient that the wire rods 4 are disposed at at least two locations in the longitudinal direction of the partial cylindrical metal casing 2.
<2> The partial cylindrical metal casing 2, the metal plate 3, and the wire 4 are all made of stainless steel (SUS). However, to reduce weight, they may be made of aluminum or other metals instead.
<3> The wire 4 used has a uniform thickness along its entire length, but in order to further reduce the contact area with the metal plate 3, it may have multiple locations along its length that have smaller diameters.
As mentioned above, the reference numerals are used for the purpose of easy comparison with the drawings, but the present invention is not limited to the configurations shown in the drawings. Furthermore, it goes without saying that the present invention can be embodied in various forms without departing from the spirit and scope of the present invention.

Reference Signs List 1: Curved surface 2: Partial cylindrical metal casing 3: Metal plate 4: Wire rod 6: Object to be insulated S: Space

Claims (3)

A metal-coated insulation device that can be arranged along a cylindrical outer peripheral surface of an object to be insulated, and that has a box-shaped partial cylindrical metal casing with a curved surface along the cylindrical outer peripheral surface, and that contains insulation material inside the partial cylindrical metal casing, in which a plurality of metal flat plates along the curved surface are stacked in the heat transmission direction inside the partial cylindrical metal casing as the insulation material, and between each of the plurality of metal flat plates and at least two locations in the longitudinal direction of the partial cylindrical metal casing, metal wire rods of uniform thickness over the entire length are wound along the curved direction from one end to the other end of the curved surface in the curved direction, forming spaces between adjacent metal flat plates in the heat transmission direction and between adjacent wire rods in the longitudinal direction of the partial cylindrical metal casing, and the surfaces of the metal flat plates are formed into mirror or nearly mirror heat ray reflecting surfaces. The metal-coated thermal insulation device according to claim 1, wherein the wires arranged between the stacked metal plates are arranged so that adjacent wires in the heat transfer direction with the metal plates sandwiched between them are shifted to different positions in the longitudinal direction of the partial cylindrical metal casing. A metal-coated insulation device according to claim 1 or 2, in which the metal plate and the wire are made of the same metal.

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