JPS60101391A - Heat-insulated conduit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to an air system which is heated relative to the surroundings and is constructed of two substantially coaxially running metal tubes with helical or ring-shaped corrugations. It relates to a thermally insulated conduit in which the metal tubes are held in their coaxial position by space holders and are thermally insulated from each other by suitable means.

A thermally insulated conduit that has become popular on the market as a remote heating conduit is known from German Patent No. 1,525,658. This conduit consists of two corrugated metal tubes arranged concentrically with each other and an insulating layer based on foamed polyurethane and provided between the corrugated metal tubes. A plastic coating is provided on the outer tube, which protects the outer tube from corrosion.

The advantage of this known construction is that, due to the corrugation of the tube, the tube structure is flexible, so that the tube can be wound on a cable drum and laid like an electric cable. The point is that it has become possible. There is no need to take into account thermal changes in length, not only when assembling the conduit sequentially, but also when laying it.

This is because the corrugation of the tube compensates for these length variations within the tube itself. Another important advantage of the known conduit is that it can be produced in virtually unlimited lengths by continuous production. As a result, during installation, there are no connection points that are unavoidable in remote heat transfer construction.

However, this known conduit also has the disadvantage that, because of the foam insulation, it is not possible to transport media with temperatures above 150 DEG C., such as superheated steam, for example. This is because polyurethane foam will be destroyed at such high temperatures.

Therefore, the basic problem of the present invention is to
The object of the present invention is to improve a thermally insulated conduit so that a medium at a temperature higher than 0.degree.

According to the present invention, this problem is solved as follows.

(8) holding the tubes by a space retainer made of ceramic material and/or hard plastic; (b) separating the ring-shaped areas between the tubes in a vacuum-tight manner at the tube ends; and (c) separating the ring-shaped areas at least It is evacuated to 10 mbar and an insulating material consisting of a tape or a filler with a metal membrane wrapped around the inner tube is provided in the ring-shaped area.

The conduit of the invention has all the advantages of known thermally insulated conduits and is also suitable for conveying media at temperatures above 150° C. with low energy losses. It has become. By evacuating the ring-shaped area, the energy losses are significantly reduced compared to known foam insulation. As a result, in the thermally insulated conduit of the present invention, if the spacing between the inner tube and the outer tube is equal, the heat loss is small, or if the heat loss is the same, the inner tube and the outer tube The distance between the two can be reduced. Since the standard diameter of the inner tube has already been determined, it is preferable to reduce the diameter of the outer tube. As a result, on the one hand, raw materials for the outer tube can be saved - this also applies to the plastic sheathing - and on the other hand, as the outer diameter of the tube structure is reduced, the amount of material needed for winding on the cable drum can be reduced. The amount of conduit available is increased.

The partitioning of the ring-shaped areas between the tubes can be done already at the factory or after the conduits have been laid at the construction site. In the area between the inner tube and the outer tube and remaining between the space holders, a metal coating tape or a metal tape is wound around the inner tube.
Alternatively, it can be filled with a filler consisting of an inorganic material, such as, for example, spongy clay.

The space holder is composed of, for example, three blocks arranged at intervals of 12o0, the blocks are composed of ceramic or hard plastic, and the blocks are
It is effective to hold it with a wire shaped like an arc. Such a space retainer can be mounted on the inner tube in a simple manner during manufacture. It is advantageous to provide the areas existing between the spacing bodies with several layers of metallized plastic tape. In order to prevent the plastic tapes from coming into contact with each other, a mesh of plastic or a suitable ceramic material can be provided between the individual layers. For manufacturing reasons, it is advantageous to construct the spacing bodies in a helical manner and to arrange the metallized plastic tape and the mesh between the spacing bodies in a helical manner. If such measures are taken, continuous production will be possible.

In known proprietary tubes, the compressive strength of the inner tube was increased through a foam locking the inner tube within the outer tube. On the other hand, in the guide a of the invention, it is advantageous to sheath the inner tube with a helically arranged metal wire or tape in order to increase the compressive strength. These metal wires and tapes are arranged on the inner tube at long pitches (0.5 to 1.0 m).

It is advantageous if the area between the tubes is evacuated to at least 10-3 mbar. Since convection no longer occurs in this vacuum, heat loss occurs exclusively through heat conduction and heat radiation. Heat radiation can be prevented to a considerable extent by metal tapes arranged between the spacers. Loss due to heat conduction can be reduced by selecting an appropriate material for the space holder.
can be kept to a minimum.

It is advantageous to provide a getter material within the ring-shaped region to absorb residual gas. Some materials, such as plastics, have a tendency to generate so-called aftergassing. That is, after the ring-shaped region is evacuated, gas molecules separate, and these gas molecules reduce the vacuum. The getter material captures these gas molecules, rendering them harmless. It is desirable to monitor the pressure in individual ring-shaped areas of the partitioned length of tube. When the inner or outer tube breaks, the pressure within the ring-shaped area increases rapidly [7, and this pressure increase is sent as an alarm to the central command center. In such cases, the damaged pipe length must be repaired or replaced. It is effective if the block of the space holder is prismatic in shape and rests on the inner tube with its flat side, while abutting the outer tube with its sharp edges.

The surface of the inner tube is curved, and the contact surface of the block is flat, resulting in point contact. This point contact makes it possible to suppress #4 conduction to a minimum. The longitudinal edge of the prism is oriented in the longitudinal direction of the tube, and the length of the edge is at least 2
equal to the distance between two wave crests. In this way, it is possible to prevent the block from tilting.

The invention will now be described in detail with reference to the embodiments schematically illustrated in FIGS. 1-3.

Corrugated metal tube with one vertical seam welded on the inner tube (
For example, it is made up of a metal tube made of special steel.

An outer tube 2 is provided concentrically with respect to the inner tube 1. Outer tube 2
Like the inner tube 1, it is constructed as a corrugated metal tube (for example, a metal tube made of common steel) with vertical seams welded. The outer tube 2ii is covered with a plastic sheath 6. A corrosion protection layer based on bitumen can also be provided between the outer tube 2 and the plastic sheath 3. The inner tube 1 and the outer tube 2 are held concentrically with each other by a space holder 4. It is effective if the space holder 4 is composed of six prismatic blocks 5, which are arranged 120 degrees apart from each other and held on the inner tube 1 by the holding line 6. do.

It is advantageous if the prismatic block 5 is made of a ceramic material or a hard plastic that can withstand high temperatures.

It is desirable that the length of the prismatic block 5 in the longitudinal axis direction is at least as follows. That is, it is desirable that each block rests on at least two corrugations of the inner tube 1 and is therefore long so that the blocks 5 do not tilt. The block 5 contacts the inner tube 1 with a flat surface. On the other hand, the tip abuts on the inner surface of the outer tube 2. Such an arrangement results in a small number of point contacts between the individual blocks 5 and the tubes 1, 2, so that the heat transfer in the area of the blocks 5 is very small. Between the spacing bodies 4 several layers of metal foil or metallized plastic foil 7 are wound onto the inner tube 1 . These layers are formed by a mat-like flexible space retainer 8 made of glass or ceramic material;
held at a distance from each other. The metallized plastic foil or metal foil 7 serves to reduce radiation losses. The ring-shaped gap between the inner tube 1 and the outer tube 2 is evacuated to reduce losses due to convection. For this purpose, this annular gap is vacuum-tightly partitioned at the ends of the individual tube lengths. Preferably, the vacuum in the annular gap is at least 10-3 mbar. In a vacuum lower than this, convection may occur, so instead of the metal foil 7 or in addition to the metal foil 7,
The filler must be accommodated in the annular gap. However, such a configuration is not preferable in terms of heat loss compared to the illustrated embodiment.

In the embodiment shown in FIG. 6, the spacer 4 has a helical design. That is, the retaining line 6 has a helical shape, so that the lateral blocks 5 contact the inner tube 1 at a distance in the longitudinal direction. In this embodiment as well, the space retainer 4 can be mounted individually on the inner tube 1. That is, it is effective if the space holder 4 is composed of six blocks 5. If the space holder 4 is configured in a spiral shape,
The effect is that the area existing between two adjacent space holders 4 also has a helical shape, so that the foil 7 and the space holder 8 can also be accommodated in this area in a helical manner as well. This is effective in continuous production.

If relatively high-pressure media have to be conveyed in the inner tube 1, it is advantageous to sheath the inner tube with a wire or tape (not shown), which is laid over the inner tube 1 in long pinches.

In this case, the sheathing can take place in one direction or in alternating directions.

According to the present invention, the conduit can already be made into a ready-made product at the factory stage. In other words, the ends can be partitioned and the air can be vented. However, it is also possible to carry out these operations after the conduit has been laid. According to the invention,
For thermally insulated conduits, heat losses are significantly lower than for similar conduits given the same geometric dimensions. Heat loss is on the order of 15-20% of the heat loss of known conduits.
It is. With the conduit according to the invention, the space between the inner tube 1 and the outer tube 2 can be selected to be much smaller, provided that the same heat losses as in known conduits are tolerated. That is, the outer diameter of the outer tube 2 can be significantly reduced. It is therefore possible to wind considerably longer pipe lengths onto the cable drum, so that the number of connection points required during installation is reduced. Furthermore, manufacturing costs are lower if the heat loss is the same.

When manufacturing a thermally insulated conduit according to the present invention, the inner tube 1 is manufactured by first forming a longitudinally shrinking metal tape, vertical seam welding of this metal tape, and then corrugation. good. The inner tube 1 is then wound around the cable drum. In the next working step, the corrugated inner tube 1 is pulled out of the cable drum, the spacer 4 is mounted on the inner tube 1 and the area between the spacers is wrapped with a foil 7 and a spacer 8. Furthermore, a so-called sticky substance can also be provided. This getter material traps the gas molecules subsequently produced by the gas after evacuation of the annular gap, thus rendering them harmless. The inner tube 1 with the space retainer 4 and the superinsulating section 7.8 is then covered with a longitudinally shrinking metal tape. The metal tape is formed into a seam-open tube, longitudinal seam welded, and corrugated. Next, the surface of the corrugated outer tube 2 is cleaned with a corrosion-preventing film, and finally the plastic coating 6 is extruded. After the plastic sheathing 3 has cooled, the finished pipe is wound onto a cable drum and either ready-made and laid as described above, or first laid and then ready-made.

[Brief explanation of the drawing]

1 is a schematic cross-sectional view of an embodiment of a thermally insulated conduit according to the invention; FIG. 2 is a schematic cross-sectional view of the conduit of FIG. 1 taken along the dashed line in FIG. 1; and FIG. 1 is a schematic cross-sectional view of an example conduit; FIG. 1...Inner tube 2...Outer tube 6...Plastic coating 4...Space holder 5...Prismatic block 6...Retaining line 7...Foil 8...Space holder substitute Mitsuyoshi Hitoezaki Agent Mitsufumi Ezaki Figure 1 1111 Figure 2

Claims (1)

[Claims] (1) Consisting of two metal tubes running substantially coaxially with spiral or ring-shaped corrugations;
A gas or a gas heated relative to the surroundings is a thermally insulated conduit for underground installation or for conveying a liquid, the metal tube being held in a coaxial position by a space holder. In a thermally insulated conduit which is thermally insulated from each other by suitable means, the tube (1, 2) is held by a spacer (4) of ceramic material and/or hard plastic. (b) the ring-shaped area between the tubes (1, 2) is vacuum-tightly partitioned at the tube ends; (c) the ring-shaped area is at least 10 = mbar
(,i) A thermally insulated device characterized in that an insulating material consisting of a tape (7) or a filler wrapped around the inner tube (1) and having a metal film is provided in the ring-shaped region. conduit. (2) Space retainer (4) by ceramic or hard plastic block (5)! Completed, block (5)
A thermally insulated conduit according to claim 1, wherein the conduit is held by an arc-shaped wire (6). (6) A thermally insulated conduit according to claim (2), wherein three blocks (5) are provided at intervals of 120°. (4) Any one of claims (1) to (3) in which at least two layers of metal-deposited plastic tape (7) are provided in the area between the space holders (4). The thermally insulated conduit according to item 1. (5) Claim (1) in which the space holder (4) is configured in a spiral shape, and the metal-deposited plastic tape (7) is spirally laid between the space holders (4).
Thermally insulated conduits as described in Section. (6) A thermally insulated conduit according to claim (1), wherein the inner tube (1) is sheathed with a metal wire or tape arranged in a spiral shape. (7) The area between the tubes (1, 2) is at least 10'mb.
A thermally insulated conduit according to claim 1, which is evacuated to ar. (8) A thermally insulated conduit according to claim (1), wherein a getter material for absorbing residual gas is provided in the ring-shaped region. (9) A thermally insulated conduit according to claim (1) for monitoring the pressure in the ring-shaped region. (10) The block (5) has a prismatic shape, and the block (5) rests on the inner tube (1) with its flat side and contacts the outer tube (2) with its sharp edge on the other hand. A thermally insulated conduit according to paragraph (1). (11) The longitudinal edge of the prism is oriented in the longitudinal direction of the tube, and the length of the edge is at least equal to the distance between two wave crests of the outer tube (2). Thermally insulated conduit as described. (12) A thermally insulated conduit according to claim (1), wherein a partition is provided at each branch point or connection point of the conduit.