DE102009050686A1 - Method and device for producing a thermally insulated pipeline, in particular for cryogenic media - Google Patents

Abstract

The invention relates to a method for producing a thermally insulated pipe (3), in particular for a cryogenic medium, in which a powder-fiber mixture (11) is applied to a hollow tube (5) as a thermal insulating layer (11 '). A device (1) provided for this purpose comprises a storage container (10) for receiving the powder-fiber mixture (11) and a conveying device (2, 28) for applying the powder-fiber mixture (11) to the hollow tube (5) and a feed device (6) for pushing out the hollow tube (5) in the longitudinal direction (7) of the tube via an outlet opening (8).

Description

The invention relates to methods for producing a thermally insulated pipeline. It further relates to a thereafter working device and a thereafter produced thermally insulated pipe, in particular for a cryogenic medium (fluid).

Against the background of decentralized energy supply, the need for storage options, especially for renewable energies, is in great demand. In the storage of larger amounts of energy, hydrogen has a great potential for use, despite the energy consumption associated with the generation and storage as a universal and cleanly usable secondary energy source. A usable cable-based system for energy storage and in particular for energy transport requires a transmission line whose central component is a thermally insulated pipeline, for example, for liquid hydrogen, helium or nitrogen. The thermally insulated tubing may be incorporated into the transmission line, which in turn has thermally coupled pipelines for transporting a cryogenic fluid and a cooling fluid.

Such a transmission line is for example from the DE 692 02 950 T2 known. The known transmission line includes a central stainless steel conduit for the cryogenic fluid, for example, liquid helium or liquid hydrogen. The steel pipe is surrounded by a multiple insulation, which in turn is loosely wrapped by a metal screen made of a thin, wound aluminum strip. The metal screen is held by means of clamps on a parallel to the central steel pipe outgoing steel pipe for a cooling fluid. The metal screen in turn is surrounded by a superinsulation, which in turn is surrounded by a vacuum enclosure.

From the WO 2005/043028 A2 is a line component for a power grid with a first line for the cryogenic energy carrier and a second line for a liquid heat transfer medium known. The first line parallel to the second line communicates with heat exchangers for vaporizing or condensing the heat transfer medium. The cables are surrounded by foil insulation and enclosed by an outer sheath. In the interior run electrical cables and signal lines, which in turn are embedded in an insulating material.

The invention has for its object to provide a particularly suitable method for producing a particularly reliable insulated pipe, in particular for the transport of cryogenic media. Furthermore, an apparatus operating according to this method should be specified.

With regard to the method, this object is achieved by the features of claim 1. Advantageous developments and variants are the subject of the dependent claims.

For this purpose, a powder-fiber mixture is applied as a thermal insulating layer on a hollow tube in a flow process with a certain pressurization or pressure. The powder-fiber mixture is free of adhesive and / or binder agents, such as adhesives or plastics, and in particular free of thermoplastics or the like.

Suitably, the hollow tube is continuously advanced in the tube longitudinal direction, while the powder-fiber mixture is pressed onto a hollow tube. The powder-fiber mixture is applied with an insulating or composite layer thickness on the hollow tube, which is preferably greater than the tube diameter of the hollow tube.

The invention is based on the idea to use an insulation material for reliable thermal insulation of a pipeline, which ensures a low heat input into the pipeline and thus optimized as possible in terms of heat transfer through solid heat conduction, heat radiation and convection. In this regard, a silica powder has been found to be particularly suitable. In order to reduce the heat radiation rate of heat transfer, a clouding agent, for example, titanium dioxide or carbon black should be used, for example, mixed with the powder.

The problem with the isolation of the pipeline only with powder is the additional condition that the central hollow tube (stainless steel tube) shifts when moving the line to a designated outer shell and would invest in this, whereby a thermal bridge can arise. Since pure beds of powder can flow and slip, whereby, for example, the hollow tube could reach the edge of the composite and the remaining insulation thickness would then no longer be sufficient, the powder should be bound. For this purpose, it was recognized that nonwovens or fiber materials should be used, which perform an additional support function within the insulation. However, these in turn should keep the heat input into the central hollow line as low as possible.

In order to ensure the lowest possible heat input of the insulating material in the hollow conduit, therefore, is a mixture of powder and Fiber preferably, wherein the fibers take over the support function, while the powder essentially performs the function of isolation against heat transfer by heat radiation, solid heat conduction and convection.

Although it is conceivable to fill the powder in foil or tissue bag and then wrap it around the hollow tube. Also, for this purpose, a previously by powdering with powder added, weakly needled nonwoven fabric could be applied for example by tape winding in several layers on the tube. However, this not only has the disadvantage of poor machinability. Rather, on the one hand undesirably arise thermal bridges on the joints and on the other hand arise wrinkles due to the winding.

However, compared to the application of the powder-fiber mixture in the form of a powdered or powder-soaked nonwoven fabric from the fiber material, a plug, d. H. a flowing and pressing the loose powder-fiber mixture on the central hollow line on the one hand a homogeneous fiber-powder composite as thermal insulation and on the other hand, due to the few points of contact of the fibers, a particularly low solid state conductivity of the insulation. In addition, avoid the fibers, in particular polyamide fibers, in the powder-fiber mixture due to their support function undesirable flow of the powder, especially in a bending of the insulated pipe in the course of its installation at the destination.

The layering of the powder-fiber mixture onto the central hollow tube, which is also referred to below as a capillary, is preferably produced according to the principle of extrusion. The application of the powder-fiber mixture takes place here in principle by flowing or pressing the most homogeneous mixture of the powder and the nonwoven fibers (nonwoven fibers) with a certain pressure on the outer circumference of the hollow tube. The composite of the powder-fiber mixture applied to the central hollow tube in this manner forms the thermal insulating layer in the desired or intended layer thickness.

In an advantageous embodiment of the applied to the central hollow tube composite of the powder-fiber mixture is wrapped with a gas-permeable bandage, suitably interposition of a braid, knitted or knitted fabric as textile-like fiber or Garnverbund. The mesh is suitably also wrapped around the insulating layer-forming composite of the pressed and homogeneously compacted powder-fiber mixture by winding or banding as well. The knit, in addition to the fibers, provides a support function for the powder within the composite.

The produced pipeline with the preferably made of stainless steel central hollow tube (capillary) thus has on the outside a thermal superinsulation in the form of compressed under pressurization mixture of polyamide fibers and silica powder, which is suitably mixed with an opacifier. The bandage wound around this composite not only holds the composite of the powder-fiber mixture together but also prevents the powder from trickling out of the composite. In addition, the bandage protects the insulation from the powder-fiber mixture.

The gas-permeable bandage also allows, as an additional function, a sliding of the thermally insulated pipeline to an outer tube surrounding this pipeline. Here, the wrapped composite of the powder-fiber mixture with thermally insulating enclosed hollow tube is suitably surrounded by a gas-tight and pressure-resistant outer sheath in the form of a stainless steel or copper corrugated pipe.

With regard to the device for producing the thermally insulated pipeline, the object is achieved according to the invention by the features of claim 6. Advantageous embodiments and variants are the subject matter of the subclaims referenced hereto.

The device has a reservoir for receiving the powder-fiber mixture. In a first variant, the reservoir opens via a filling or passage opening in a container bottom arranged on the cavity of a preferably cylindrical screw housing into which the powder-fiber mixture (vertical) is incident. From this hollow cylindrical screw housing, which has the outlet opening, the powder-fiber mixture is expressed transversely to the direction of fall over again an outlet opening.

A conveyor serves to apply the powder-fiber mixture to the hollow tube. Particularly suitable for this purpose is a hollow auger, also referred to below as a hollow screw, in the manner of an extruder or a screw extruder. The hollow screw is rotatably mounted on the container bottom of the reservoir in the hollow cylindrical screw housing.

The hollow tube is led out by means of a feed device in the tube longitudinal direction through the hollow screw and out of the extruder, for example, nozzle-like or out of a nozzle head outlet opening. The hollow screw is expediently electromotive rotationally driven at a variable speed.

To avoid a backflow of the conveyed by means of the hollow screw powder-fiber mixture in the reservoir back in a preferred embodiment of the first variant, the filling opening partially, in particular semi-closed. For this purpose, the filling opening extends from the vertex of the cylindrical housing wall of the worm housing only on one side in one of the two circumferential directions. At the top, at least approximately vertically, a first funnel wall of the storage container extends, so that the housing wall of the screw housing is closed on the rear side of this funnel wall facing away from the container interior of the storage container.

The filling opening thus begins approximately at the apex of the housing and extends from there with clockwise rotating hollow screw in a clockwise direction to a second funnel wall. This, opposite the first funnel wall second funnel wall closes the filling opening at an angular distance from the vertex and the first partition in the circumferential direction.

In an expedient development of this embodiment, a number of Aufrührstegen is arranged on the housing inner wall of the screw housing. These extend in the housing longitudinal direction within the screw housing vorzugsweises parallel to the screw axis of the hollow screw. This web arrangement additionally prevents a backflow of the conveyed by means of the hollow screw powder-fiber mixture in the reservoir back.

In a second variant, the powder-fiber mixture is squeezed out directly via the bottom-side outlet opening from the reservoir, which is filled with the powder-fiber mixture. For this purpose, the central hollow tube is passed through a suitably funnel-shaped reservoir (funnel container) and exits through the outlet opening (funnel opening).

Around the vertically guided by the hopper hollow tube around the powder-fiber mixture, for example, by arranged on the container circumference conveyor belts, pressed or pressed onto the hollow tube and ejected through the nozzle-like or nozzle effective outlet or funnel opening. The hollow tube emerging from the funnel container and encased in the insulating layer of the powder-fiber mixture is then wrapped in a similar way to the first variant with a braid or knitted fabric and then with a gas-permeable bandage.

The hollow tube (capillary) carrying the medium suitably consists of a non-rusting austenitic steel and is temperature-resistant, in particular low-temperature resistant. Therefore, the hollow tube is also at a temperature of minus 255 degrees Celsius (-255 ° C), in particular at a pressure of less than or equal to 20 bar, sufficiently resilient. The inner diameter, d. H. the clear values of the hollow tube of this central pipeline is suitably 0.5 mm to 50 mm, advantageously 1 mm to 30 mm, for example 1.1 mm to 20 mm.

For example, a central stainless steel hollow tube with an outer diameter of 6 mm and an inner diameter of 3 mm made of X2Cr Ni Mo17-12-2 is suitable. The layer thickness of the insulation (powder-fiber composite) is greater than the outer diameter of the hollow tube, wherein the ratio between the pipe outside diameter to the composite layer thickness of the insulation is suitably at least 1: 2.

The ratio of the weight fractions of the fibers (nonwoven) to the powder is based on an optimization of the highest possible powder content while at the same time as high as possible, but at least sufficient support function by the fibers. A ratio of one part by weight of fibers to eight parts by weight of powder (mass [g] of fibers: mass [g] of powder = 1: 8) has proven to be particularly expedient.

The thermally insulated pipe is at least so flexible that it can be laid similar to a ground cable. The super-insulation of this pipeline, consisting of the powder-fiber mixture or composite, enables cost-effective installation and effective operation over a laying range of several kilometers. The thermally insulated piping is also suitable for transporting hot media, in particular gas or high-temperature liquids.

Followings embodiments of the invention will be explained in more detail with reference to a drawing. Show:

1 schematically a first variant of an extruder-like device for producing a thermally insulated pipe for cryogenic media, with a reservoir for a powder-fiber mixture and with a pick screw conveyor (hollow screw) through which a hollow tube is guided,

2 in a longitudinal section of the extruder according to 1 with a drive unit,

3 in a cross section of the extruder according to 2 with half funnel-shaped container,

4 schematically a second variant of the device with a provided with lateral conveyor belts funnel-shaped reservoir into which the hollow tube enters vertically from above,

5 in a plan view of the device according to 4 with hexagonal reservoir, and

6 in cross-section the structure of the thermally insulated pipe, in particular for cryogenic media.

Corresponding parts are provided in all figures with the same reference numerals.

In the 1 to 3 a device 1 in the form of an extruder, ie a screw press with a hollow screw conveyor, hereinafter referred to as a hollow screw 2 for the production of a thermally insulated pipeline 3 , preferably for cryogenic media, for example for liquid hydrogen. Through the cavity 4 the screw conveyor 2 is a hollow tube (capillary) 5 the insulated pipe to be manufactured 3 guided.

For transporting the hollow tube 5 is a feed device 6 provided in the form of, for example, two motor-driven rollers. The feed device 6 drives the hollow tube 5 with continuous feed rate in the tube longitudinal direction 7 through the hollow screw 2 through and over an outlet (nozzle exit) 8th on a screw housing 9 of the extruder 1 out.

The snail shell 9 is located below a storage container 10 that with a powder-fiber mixture 11 is filled. The storage container 10 stands with the snail shell 9 via a bottom-side passage or filling opening 12 in conjunction, over which the powder-fiber mixture 11 in the housing interior 13 of the snail shell 9 incident. At the outlet 8th the hollow screw conveyor 2 or at the nozzle outlet, the powder-fiber mixture sets 11 around the central hollow tube 5 and is using this through the outlet 8th squeezed or pressed.

The diameter difference between the inside or opening diameter of the outlet opening 8th and the tube outside diameter of the hollow tube 5 , ie the clear width between the opening edge of the outlet opening 8th and the hollow tube 5 determines the layer thickness of the insulation material from the composite 11 ' of the compressed powder-fiber mixture 11 , For this purpose, the worm housing tapers 9 , in the interior of the housing 13 the snail 9 is rotatably mounted, in a nozzle head 14 to the outlet 8th out.

One at the outlet 8th or at the nozzle outlet to this powder-fiber composite 11 ' applied mesh or knit (knitted fabric) 15 fixes the powder-fiber mixture 11 , To this composite 11 ' then becomes a gas-permeable bandage 16 wound. Both the knitwear 15 as well as the bandage 16 suitably by banding, for example by means of a tangential or radial winder by Z-beat (right-hand stroke) and / or by S-stroke (left-hand stroke) to the powder-fiber composite 11 ' wound. The bandage 16 avoids, inter alia, trickling out of the powder from the composite 11 ' ,

The 2 and 3 show a special embodiment of the extruder device 1 with an electromotive drive device 17 that the hollow screw 2 with preferably continuous speed, for example, clockwise drives. For this purpose, the drive device 17 a correspondingly controllable electric motor 18 on. The drive device 17 and the hollow screw 2 thus form the conveyor for applying the powder-fiber mixture 11 on the hollow tube 5 ,

On the inner circumference of the cylindrical screw housing 9 are stir-bars 19 arranged evenly distributed on the inner circumference. The Aufrührstege 19 extend within the snail shell 9 on the inner wall in the tube longitudinal direction 7 and preferably uninterrupted over at least approximately the entire housing length of the screw housing 9 , The Aufrührstege 19 prevent adhesion of the powder-fiber mixture 11 on the housing inner wall of the screw housing 9 , In addition, prevent the Aufrührstege 19 a backflow of the powder-fiber mixture 11 back to the reservoir 10 ,

For effective prevention of backflow of the means of the hollow screw 2 in the tube longitudinal direction 7 promoted powder-fiber mixture 11 in the reservoir 10 back, is the filling hole 12 only in a range between an in 3 illustrated vertical centerline 20 and one with this in the screw rotation axis 21 cutting horizontal center axis 21 open. Based on the circular cross-section of the screw housing 9 surrounding housing interior 13 this corresponds to a circle segment in the first quadrant.

A first funnel wall 23 is in the range of the vertical center axis 20 intended. This first funnel wall 23 extends from the vertex 24 of the cylindrical screw housing 9 vertically, taking on the back 25 the snail shell 9 closed is. The filling opening 12 extends from this first funnel wall 23 up to a second funnel wall 26 to the first funnel wall 23 at an inclination angle α obliquely. The angle is in the embodiment α = 45 °.

During operation of the device 1 becomes the powder-fiber mixture 11 that is in the reservoir 10 located, through the filling opening 12 by means of the hollow screw conveyor 2 in the snail shell 9 retracted and by means of the screw conveyor 2 at least slightly compressed and in the tube longitudinal direction 7 forward to the outlet opening 8th pushed out. The hollow tube 5 is also in the tube longitudinal direction 7 through the hollow conveyor screw 9 passed and occurs at the outlet 8th of the pointed nozzle head 14 out. At this point, the insulating material settles out of the compacted powder-fiber mixture 11 around the central hollow tube 5 around and is with this through the outlet opening 8th pressed. The subsequently applied mesh or knit 15 fix this in the composite 11 ' possibly still loose powder-fiber mixture 11 while the subsequent bandage 16 a trickling out of the powder from the composite 11 ' avoids.

The 4 and 5 show an alternative embodiment of the device 1 for the production of the thermally insulated pipeline 3 , The storage tank 10 is a polygonal, for example, hexagonal funnel with a corresponding number of wall segments 27 executed. At these sidewall segments 27 are in the area of the funnel floor, ie as close as possible to the outlet opening 8th in motorized conveyor belts 28 with drive or deflection rollers 29 intended.

Ds central hollow tube 5 is, for example, in turn by means of an electric motor driven feed device 6 vertically through the with the powder-fiber mixture 11 fed funnel-shaped reservoir 10 guided while the powder-fiber mixture 11 by means of conveyor belts 28 on the central hollow tube 5 pressed and through the outlet opening 8th is ejected.

Analogous to the embodiment according to the 1 to 3 then becomes the composite 11 ' from the compacted powder-fiber mixture 11 , which is the thermal insulation of the pipeline 3 represents, with the textile fiber composite 15 wrapped in the form of a braid or knitted fabric. Then, in turn, around this composite structure, the gas-permeable bandage 16 wound.

During operation of the device 1 according to the 4 and 5 becomes the powder-fiber mixture 11 as insulation by means of the conveying direction 30 driven conveyor belts 28 on the central Hohlohr 5 pressed and over the container bottom side nozzle head 14 from the outlet 8th pushed out. The subsequently transferred braid or knit 15 in turn serves to fix the powder-fiber mixture 11 or the or powder-fiber composite 11 ' while the subsequent bandage 16 again to avoid trickling out of the powder. The conveyor may be in addition to the conveyor belts 29 also have a vibrator. This allows the discharge of the powder-fiber mixture 11 from the container 10 be improved.

6 shows in cross section the layer structure of the produced thermal pipeline 3 , The central hollow tube 5 is suitably a temperature-resistant stainless steel tube having an inner diameter D _i of 0.5 mm to 50 mm, preferably 1 mm to 20 mm. As an example, consider a stainless steel tube 5 assumed with an inner diameter D _i = 3 mm and an outer diameter D _a = 6 mm. The composite layer thickness V of the thermal insulation is suitably at least twice the outer diameter D _{a of} the stainless steel tube 5 , In the exemplary embodiment, the insulating or composite layer thickness V = 12 mm.

This composite 11 ' from the loosely compressed powder-fiber mixture 11 is with a braid or knit 15 surrounded by a mesh layer thickness G of about 1 mm. The mesh layer thickness G can also be greater, for example, several millimeters or even smaller, if so that the support function is ensured.

The around this composite 11 ' wrapped bandage 16 can be a bandage layer thickness B of one or a few millimeters, z. B. about 1 mm to 5 mm, up to a few centimeters.

The preferably gas-permeable bandage 16 assumes several functions. On the one hand, it should be the thermal fiber-forming powder-fiber composite 11 ' stick together. Furthermore, the bandage 16 a sliding of the thermal pipeline 3 on an outer jacket 31 , For example, in the form of a corrugated pipe made of stainless steel or copper allow. In addition, the bandage 16 the insulation from the powder-fiber mixture 11 protect. The braid 15 assumes an additional support function for the powder-fiber composite 11 ' while the fibers themselves already have a supporting function for the powder within the mixture 11 or composite 11 ' represent. The bandage layer thickness B is therefore to be dimensioned such that these functions are reliably fulfilled.

LIST OF REFERENCE NUMBERS

1

contraption

2

Hollow / auger

3

thermally insulated piping

4

cavity

5

Hollow / stainless steel pipe

6

feeder

7

Tube longitudinal direction

8th

outlet opening

9

snail shell

10

reservoir

11

Powder-fiber mixture

11 '

Powder-fiber composite / isolation

12

Continuity / fill opening

13

Housing interior

14

nozzle head

15

Knit / weave

16

bandage

17

driving means

18

electric motor

19

Aufrührsteg

20

vertical centerline

21

Screw rotation axis

22

horizontal centerline

23

first funnel wall

24

vertex

25

back

26

second funnel wall

27

wall segment

28

conveyor belt

29

Drive / idler pulley

30

conveying direction

31

outer sheath

B

Bandages layer thickness

D _a

outer diameter

D _i

Inner diameter

G

Braided layer thickness

V

Composite layer thickness

α

tilt angle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 69202950 T2 [0003]
• WO 2005/043028 A2 [0004]

Claims (15)

Method for producing a thermally insulated pipeline ( 3 ), in particular for a cryogenic medium, in which a powder-fiber mixture ( 11 ) on a hollow tube ( 5 ) as a thermal insulating layer ( 11 ' ) is brought up. A method according to claim 1, characterized in that the hollow tube ( 5 ) surrounding insulating layer ( 11 ' ) from the powder-fiber mixture ( 11 ) with a textile-like fiber composite ( 15 ) is wrapped. A method according to claim 1 or 2, characterized in that the hollow tube ( 5 ) surrounding insulating layer ( 11 ' ) from the powder-fiber mixture ( 11 ) with a gas-permeable bandage ( 16 ) is wrapped. Method according to one of claims 1 to 3, characterized in that the powder-fiber mixture ( 11 ) on the hollow tube ( 5 ) is applied with a composite layer thickness (V) which is greater than the outer diameter (D _a ) of the hollow tube ( 5 ), preferably at least twice as large. Method according to one of claims 1 to 4, characterized in that the fibers, in particular polyimide fibers, and the powder, in particular silica powder, in a mixing ratio in proportions greater than 1: 2, suitably greater than 1: 5, preferably 1: 8, on the hollow tube ( 5 ) are applied. Contraption ( 1 ) for producing a thermally insulated pipeline ( 3 ), - with a storage container ( 10 ) for receiving a powder-fiber mixture ( 11 ), - with a conveyor ( 2 . 28 ) for applying the powder-fiber mixture ( 11 ) on the hollow tube ( 5 ), and - with a feed device ( 6 ) for pushing out the hollow tube ( 5 ) in the tube longitudinal direction ( 7 ) via an outlet opening ( 8th ). Contraption ( 1 ) according to claim 6, characterized in that the storage container ( 10 ) is funnel-shaped. Contraption ( 1 ) according to claim 6 or 7, characterized in that the storage container ( 10 ) on the bottom side via a filling opening ( 12 ) in a cylindrical screw housing ( 9 ), in which a hollow screw conveyor ( 2 ) is rotatably mounted. Contraption ( 1 ) according to claim 7, characterized in that to avoid backflow of the means of the hollow screw conveyor ( 2 ) promoted powder-fiber mixture ( 11 ) in the reservoir ( 10 ) back the filling opening ( 12 ) starting from the housing crest ( 24 ) of the cylindrical screw housing ( 9 ) is open only in the one circumferential direction and closed in the other circumferential direction. Contraption ( 1 ) according to claim 7, characterized in that a first funnel wall ( 23 ) of the reservoir ( 10 ) starting from the housing crest ( 24 ) runs vertically, and that a second funnel wall ( 26 ) at an angle of the filling opening ( 12 ) with the first funnel wall ( 23 ) includes an inclination angle α <90 °, preferably α <60 °. Contraption ( 1 ) according to one of claims 8 to 10, characterized in that the screw housing ( 9 ) inside a number of longitudinal ( 7 ) running Aufmührstegen ( 19 ) having. Contraption ( 1 ) according to claim 6 or 7, characterized in that - the outlet opening ( 8th ) at the container bottom of the reservoir ( 10 ) is provided, - that the hollow tube ( 5 ) in the reservoir ( 10 ) enters vertically and via the outlet opening ( 8th ) from the reservoir ( 10 ), and - that the conveyor ( 28 . 29 ) a number of conveyor belts ( 28 ), which on the container wall ( 27 ) of the storage container ( 10 ) are arranged. Pipeline ( 3 ) with a thermal insulating layer ( 11 ' ) from a powder-fiber mixture ( 11 ), in particular of silica powder and polyimide fibers. Pipeline ( 3 ) according to claim 13, with at least one winding layer of a mesh or knitted fabric ( 15 ). Pipeline ( 3 ) according to claim 13 or 14, with at least one winding layer of a gas-permeable bandage ( 16 ).

Images