SE501471C2 - Insulated piping - Google Patents

Abstract

An insulated pipe comprises an inner fluid pipe (1), an outer jacket pipe (3), as well as an insulation (5, 6, 7) arranged therebetween. The insulation consists of a plurality of insulating bag units (5, 6), each having a flexible bag wrapping enclosing a high-insulating, fine-grained powder material in a moisture- and vacuum-proof manner, the insulating bag units substantially filling the space between the fluid pipe and the jacket pipe, and of an insulating foam (7) filling the interspaces (9, 10, 11) between the insulating bag units as well as between the latter and the two pipes.

Description

501 471 10 15 20 25 30 35 2 bands between inner and outer tubes.

Summary of the invention The above-mentioned objects are achieved in that the pipeline according to the invention has the features stated in the appended claims.

The invention is thus based on the principle that the insulation mainly consists of a plurality of specially produced insulating bag units, and remaining spaces between the insulating bag units and between them and the two concentric pipes are filled with an insulating foam. The insulating bag units have a very high insulating ability and consist of a flexible bag casing which, in a moisture-proof and vacuum-tight manner, encloses a highly insulating, fine-grained powder material, which is preferably silica aerogel, especially blackened one, or diatomaceous earth.

The insulating bag units are advantageously compacted and / or evacuated to a suitable extent. In other words, they can have a design similar to that of vacuum-packed coffee packages. Insulating bag assemblies of this kind can, as the person skilled in the art readily realize, be easily and efficiently manufactured fully automatically in machines suitable for this purpose.

As mentioned, the insulating pass units mainly fill the space between the two pipes, typically to at least about 70%, preferably to at least about 80-85%. This means that the other volume to be filled with insulating foam is relatively small, which is why the requirements for the insulating foam, which has a higher thermal conductivity, do not have to be as high. In other words, the foam can be, for example, carbon dioxide-blown power-transmitting polyurethane foam, without the total insulating ability being adversely affected to any appreciable degree.

The insulating bag units are advantageously arranged circumferentially or overlapping each other, so that paths from the inner fluid pipe to the outer jacket pipe outside the insulating bag units have a length which substantially exceeds the radial distance between the fluid pipe and the jacket pipe. ÅRE '10 15 20 25 30 35 501 471 3 This improves the thermal insulation through the foam.

The insulating pass units can have an elongated, generally flattened configuration. The length can be equal to the length of the pipeline or, when the pipe length is large, for example half of it. As will be appreciated, this means that in the manufacture of the pipeline the insulating units can easily be slid longitudinally into the space between the inner and outer tubes from one side and / or both holes, possibly using spacer or support elements, before subsequent foam blowing takes place. room.

According to a first preferred embodiment, the insulating units in cross section have a thin side and a thick side, the thin parts of the insulating units connecting to the fluid pipe and the thick parts of the insulating units connecting to the jacket pipe and wherein the insulating units in cross section generally have a substantially extending from the radial direction. The insulating units can have a wing-like profile in cross section.

The above-mentioned embodiment means that the insulating bag units can be of a standard size usable for a number of pipeline dimensions, the inclination of the insulating bag units relative to the radial direction being adapted to the radial distance between the fluid pipe and the jacket pipe.

According to a second preferred embodiment, the insulating bag units, seen in cross section, are arranged in two or more concentric annular layers, the successive insulating bag units in an annular layer being so offset relative to the successive insulating bag units in adjacent annular layers that gaps between successive insulating pass units in an annular layer are offset circumferentially relative to corresponding gaps in adjacent annular layers. Said gaps can, seen in cross section, extend inclined relative to the radial direction. The insulating unit units may have a curved configuration for adaptation to cylindrical tubular shape, but this is not necessary. 1501 471 10 15 20 25! As the person skilled in the art will readily realize, with this embodiment insulating layers of different thicknesses can be built up between the inner and outer pipes using only one or possibly two different sizes of the prefabricated insulating bag units.

With regard to the powder material, it has been found that this should be at least so fine-grained that the heat conduction decreases with decreasing gas pressure and preferably so fine-grained that maximum thermal insulation is achieved even at a relatively moderate vacuum. The powder grains should have a high strength against compressive load but at the same time have a low density. The powder must not be significantly deteriorated by high temperature or by temperature cycling.

We have found that suitable powder materials are based on silica. As previously mentioned, silica airgel and fine-grained diatomaceous earth are suitable materials.

The grain size of the diatomaceous earth is suitably in micrometer size (less than 0.1 mm). Its bulk density can be a few hundred kg / m3, typically about 250 kg / m3.

When using diatomaceous earth, the insulating bag units can suitably be evacuated to a pressure lower than about 10 mbar, preferably to a pressure lower than one or a few mbar.

The silica aerogel is usually 3-4 mm 2 of granules. We prefer to have the granules granulated so that a largest particle size of about 1 mm is obtained.

The bulk density is suitably between about 100 and about 250 kg / m 3. We prefer to be towards the lower limit.

The airgel may be translucent or pigmented (blackened). The latter is preferable, since better thermal insulation is then obtained.

The silica aerogel is suitably evacuated to a pressure lower than about 100 mbar. Particularly good insulation values are obtained at a pressure lower than about 1 mbar.

With regard to the bag cover, high demands are placed on moisture and vacuum barrier, as well as on strength, durability, low temperature sensitivity, ability to withstand shear stress and collapsibility. Taking this into account, we have found that the cover material suitably consists of laminated plastic-metal foil or pure plastic foil.

A typical laminated foil has 3 to 5 different layers.

Finally, there are one or two plastic layers, for example polyethylene, polypropylene and / or polyester. In the middle there is a layer of metal foil, for example aluminum foil. At the bottom there is again one or two polymer plastic layers. Total foil thickness can typically amount to about 150 μm. The cover can be easily heat-sealed welded, for example with the help of electrically heated jaws.

A homogeneous plastic foil can, for example, be a high-temperature polymer with low oxygen diffusion and with a thickness of the order of a few tenths of a mm.

Finished casing covers can be filled with powder and then evacuated and sealed in a vacuum chamber. Those skilled in the art will recognize that fully automatic evacuation and welding machines provide the opportunity for a rational manufacturing process.

In order to improve the friction fixing in the finished pipeline, the outer casings can have a friction-fixing structure on the outside. They can, for example, be ribbed, pleated or otherwise structured to provide better engagement with the insulating foam.

The invention will be further described in the following by means of exemplary embodiments with reference to the accompanying drawing.

Short description_of the drawing Pig. 1 on an insulated pipeline according to the invention, wherein iso- is a schematic perspective view of an exemplary configuration shown in simplified form in the pipe end surface.

Fig. 2 shows an example of an insulated pipeline according to the invention. is a schematic cross-sectional view of another Figs. 3 and 4 are schematic cross-sectional views of the same kind as Fig. 2, which illustrate two further examples of the construction of the insulation in the pipeline. 501 471 10 15 20 25 30 35 6 Fig. 5 is a schematic cross-sectional view of an example of an insulating bag unit for use in accordance with the present invention.

In the various figures, the same or corresponding parts have been marked with the same reference numerals.

Description of embodiments Figs. Embodiment of an insulated pipeline according to the invention schematically illustrates the construction of an embodiment. The straight pipeline comprises an inner fluid-metal pipe 1 and a concentric, outer jacket-plastic pipe 3 therewith, between which pipes there is an entire space-filling insulation consisting of insulating bag units 5, 6 and intermediate insulating foam (PUR) 7. The insulating bag units 5, 6 have in the form of elongate, flattened and slightly arched units, which are inserted into the pipe space in its longitudinal direction. The units can typically have a width of size 5-10 cm, a thickness of the size a few or a few cm and a length of up to several meters. In the case of, for example, pipelines with a standard length of 12 m, insulating bag units with a length of 6 m can be pushed towards each other from the respective pipeline end before foaming.

As will be readily appreciated by those skilled in the art, suitable spacers and support members for the ends of the insulating bag units may be provided so that the insulating bag units are positioned during foaming.

The insulating bag units 5, 6 are arranged in succession in two concentric rings (seen in cross section). The inner ring comprises six narrower units 5 and the outer ring 6 wider units 6. It will be appreciated that the units lie close together and close to the pipes and thus substantially fill the insulation 9 ", 11" which is present between adjacent units and the mixing space. The insulating foam-filled spaces 9 ', 10, 11', lan units and tubes are thus small in reality.

The units 5, 6 in the respective rings are staggered relative to each other, so that a gap 9 'between the units 5 in the inner ring is offset relative (here approximately in the middle) adjacent gaps 9 "between 10 15 20 25 30 35 501 471 7 units 6 in the outer ring, as a result of which the heat leakage path through the insulating foam 7 becomes substantially longer than the radial distance between the inner and outer tubes 1, 3, as indicated by the dashed line 13.

The side surfaces of the units 5, 6 could be inclined relative, i.e. form an angle with the radial direction, whereby the heat leakage path, as will be appreciated, is further extended.

In this case, the units have a cross section such as a flattened diamond. An example of this is illustrated in Fig. 5, which shows an enlarged cross-section through such an insulating bag unit 55. The unit has a bag housing 57 which, in a moisture and vacuum-tight manner, encloses a compacted and evacuated blackened silica airgel S9. The bag cover is heat-sealed longitudinally at the upper right longitudinal edge 61. The outer surface of the bag cover is provided with small projections or knobs 63, which cooperate with the insulating foam 7 to provide better friction fixation.

Fig. 2 schematically illustrates the construction of another embodiment of an insulated pipeline according to the invention. The construction is as in Fig. 1, although the insulating bag units 15 here have a different shape and location. Insulate the narrow side 17 of the units 15 connecting to the inner tube 1 and the wide side 19 of the units 15 connecting to the outer tube 3.

The general extent of the units, seen in cross section, the loupe units are wing-like in cross section with inner side 17 and wide outer side 19. The narrow one takes significantly relative to the radial direction of the pipeline, as indicated by the dashed line 21. It is understood that by suitably adapting the inclination of the units 15 can use units of a single standard design for insulation of pipelines with very varying requirements for insulation thickness, ie different distances between inner and outer pipes. Strong slope means that the heat leakage path through the insulating foam 7 is extended here in an advantageous way. 501 471 10 15 20 25 30 35 8 Fig. 3 shows an example of a modified embodiment of the insulating bag units in relation to Fig. 2. In order to further improve the adaptation to the larger circumference of the jacket tube 3, the wide end 29 of the insulating bag units 25 has thus been further widened here. In this case, the units 25 have an almost triangular shape seen in cross section.

Fig. 4 schematically shows a further modified embodiment of the insulating bag units 35. The units here have in that the units facing outwards from the inner end edge 37 have an almost space-like high shape, surface has a first part 39 which extends substantially along the inner tube 1 The corresponding outwardly facing surface 41 is longer in circumferential direction for adaptation to the larger diameter of the outer tube 3 and terminates in an elongate pointed side edge 43.

This again extends the heat leakage path through the insulating foam from the inner tube 1 to the outer tube 3.

An embodiment with a pointed-out inner and / or outer side edge, which in principle is applicable to all exemplary embodiments shown, can also be advantageous from a manufacturing point of view, since such a side edge can advantageously be achieved in connection with the sealing of the respective insulating unit after evacuation. hence.

As will be appreciated, the embodiments of insulating bag units according to the invention shown in Figs. 1-5 can be arranged in a manner which involves adaptation to most of the pipe dimensions available on the market. It is of course also possible to combine insulating bag units, in particular of the embodiment shown in Figs. 3 and 4, with insulating bag units of the type shown in Figs. 1 and 5, in order to provide a combined built-up pipe insulation with a larger radial dimension.

Claims (2)

1. 0 15 20 25 30 35 501 471 - 9 CLAIMS 1. Insulated pipeline, in particular so-called culvert pipeline, comprising an inner fluid pipe (1) and an outer jacket pipe (3) and an insulation arranged therebetween, characterized in that the insulation consists of a plurality of insulating bag units (5, 6; 15; 25; 35), each of which has a flexible casing which, in a moisture-proof and vacuum-tight manner, encloses a highly insulating, fine-grained powder material, the insulating bag units substantially filling the space between the fluid tube and the jacket tube. an insulating foam (7), which fills the gaps between the insulating pass units and between the latter and the two pipes and which is preferably a solid, force-transmitting foam, such as polyurethane foam. Pipeline according to claim 1, characterized in that the insulating bag units (5, 6; 15; 25; 35) are arranged wrapped or overlapping each other, so that paths (13) from the fluid pipe (1) to the jacket pipe (3) outside the insulating bag units have a length which substantially exceeds the radial distance between the fluid pipe and the jacket pipe. is known from the fact that the insulating bag units (5, 67 15; 25; 35) have an elongated, generally flattened configuration. Pipeline according to claim 3, characterized in that the insulating bag units (15; 25; 35) have a thin section and a thick section in cross section, wherein 3. Pipe according to claim 1 or 2, the thin sides of the insulating bag units connect to the fluid pipe (1) and the thick end portions of the insulating bag units connect to the jacket pipe (3) and the insulating bag units in cross section generally extend in a direction which deviates substantially from the radial direction. Pipe according to claim 4, characterized in that the insulating bag units (15) in cross section have a characteristic wing-like profile. 501 471 10 15 20 25 30 35 10 6. A pipeline according to claim 4 or 5, characterized in that the insulating bag units (15:25) are of a known standard size for a number of pipeline dimensions, the inclination of the insulating bag units relative to the radial direction. is adapted to the radial distance between the fluid tube (1) and the jacket tube (3). Pipe according to Claim 3, characterized in that the insulating bag units (5, 6) are arranged in cross section in at least two concentric annular layers, the insulating bag units (5) lying one behind the other in one annular layer being so offset relative the successive insulating bag units (6) in the second annular layer so that gaps (9 ') between successive insulating bag units (5) in an annular layer are displaced circumferentially relative to corresponding slots (9 ") in adjacent annular layers ( Pipe according to claim 7, characterized in cross-section, sloping relative to the radial direction, extending from the columns, extending 9. Pipe according to claim 7 or 8, characterized in that the insulating bag units (5, 6 ) has a curved configuration 10. characterized in that the bag housings (57) have an outer friction-fixing structure (63). 11. characterized by 15; 25; 35) are compacted 12. characterized by pipeline according to any of preceding claim, Pipeline according to any one of the preceding claims, that the insulating bag units (5, 6; and / or evacuated. A pipeline according to any one of the preceding claims, that the powder material (59) is silica aerogel, the insulating bag units preferably being evacuated to a pressure lower than about 100 mbar, in particular lower than one or a few mbar, or diatomaceous earth, the insulating bag units being preferably evacuated to a pressure lower than 10 mbar, especially lower than about 1 mbar. Pipe according to any one of the preceding claims, characterized in that the insulating bag units (5, 6; 15; 25; 35) fill the space between the fluid pipe and the jacket pipe to at least about 70%, preferably at least about 80-85%.