DE9000710U1 - Device for transporting media using thermally insulated pipes - Google Patents

Description

Hans-Jürgen Müller Gerhard D. Schupfner

Telephone: (o89) 4 706055/56 Hans-Peter Gauger Telex: 523016 Patent Attorneys Telefax: (0)89-472883 Poetfach 8013J89_ r„r . .7..WTlS Telegram/cabte: Lucäe-Grahn-StraBe 38 European PaWfK Zetapaten»· Mönchen D-8000 Munich 80 European officers with certificates

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The invention relates to a device of the type mentioned in the preamble of claim i .

Devices are already known and are used, for example, to supply warm gases or liquids to processing stations. To ensure that the medium does not cool down too much on the way to the relevant processing station and, for example, does not reach the dew point in the case of gases, the cooling in cooler surroundings must be reduced by the insulating layer, e.g. a mineral wool pack.

The invention is based on the task of modifying a device of this type in such a way that larger losses of heat energy are prevented using simple means while requiring little space. The device should be characterized by a simple structure and should also be easy to assemble and disassemble.

The invention is characterized in claim 1 and further embodiments are claimed in subclaims; further improvements of the invention are indicated in the description.

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The heating conductor is applied as a thin strip or tubular material to a tube made of electrically conductive material and is expediently wound along the tube in a spiral shape, so that the invention is limited to this spiral arrangement. The heating conductor can also be designed in the form of several parallel individual heating conductors extending lengthwise along the outer surface of the core tube.

) In the invention, the electric current is conducted directly through the heating bands located on the outer jacket of the core tube, whereby the heat extraction from the core tube and the medium passed through it is counteracted even better and more easily and considerable simplifications result with little space requirement.

Furthermore, the device can also be used as a heating device for heating the medium in the core tube.

Electrical and thermal insulation is placed radially around the structural unit formed by the heating conductor and the core tube, which consists of the thermal insulation layer and in particular an additional jacket tube.

While the insulating layer should have the best possible thermal insulation capacity through appropriate choice of wall thicknesses and material so that no heat energy from the heating conductor is lost radially outwards, the material of the core tube and/or its wall thicknesses in the case of a heating device should be selected so that the lowest possible heat transfer resistance is created between the heating conductor on the outside of the core tube and the inner surface of the core tube, as this allows the medium inside the core tube,

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in particular a liquid or gas flowing through it is heated up rapidly.

It is recommended to use relatively wide flat strips as heating conductors so that the heating conductor cools over a large area with the outer surface of the core tube. The cross-section, the material and the supply of electrical energy to the heating conductors should be selected so that the permissible operating temperature of the core tube is not reached.

As a precautionary measure, it is recommended that a thermal sensor be installed in the area of the core tube so that a monitoring device detects when the heating conductors heat the core tube to too high a temperature, whereupon a precautionary shutdown or reduction of the supply of electrical energy to the heating conductor should be provided.

The core tube should be made of an electrically insulating material PP, PE, PVDF, PTFE.

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While the use of plastic, especially PE, is recommended for the outer jacket pipe, the insulation layer should consist of electrically insulating plastic foam, preferably PU foam. Polystyrene and mineral or rock wool can also be used. The jacket pipe can also be made of steel, aluminum and other metals.

Copper, aluminium or steel are recommended as materials for the heating conductor, i.e. an electrically conductive material that can heat up when current flows through it due to its special electrical resistance.

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Using pipes according to the invention, entire heating pipe systems can be constructed in a further development of the invention. For this purpose, it is recommended that core pipes abut one another with their end faces and that a pipe sleeve is placed over the end parts of the adjacent core pipes, which connects the two core pipes

extend some distance along the adjacent and particularly abutting core tubes, should expediently be made of the same material as the core tubes, particularly GRP, and should be glued to the end sections of the core tubes. In this area of the end sections, the heating conductors are expediently removed. The heating conductors of the adjacent core tubes are then expediently connected by an electrical connecting cable, which is led radially outside the pipe socket and is electrically connected to the remaining heating conductors on the core tubes via connecting clamps. For this purpose, such connecting clamps are placed around the outer circumference of the core tubes in the area of the heating conductors and in contact with them. norunf &agr;&agr; ITrtnt-alftTirvrano on. en Honen

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the electrical connecting cables can be inserted, for example, by plugging them into contact sockets.

Electrical connecting cables for connecting the heating conductors to the electrical voltage source can also be made using terminal boards, electrical junction boxes or similar. The electrical "heating circuit" is preferably galvanically separated from the other electrical devices using an isolating transformer. This ensures that if the insulation is destroyed, touching a live part is safe. Monitoring devices for the functioning of the insulation are also recommended, so that if the insulation resistance falls below the required level, an alarm is triggered and/or the electrical current is switched off.

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becomes.

It has been shown that the device according to the invention can be used even in potentially explosive areas of zones 1 and 2 and temperature classes T1 to T3 without additional measures. In these cases, small/medium-sized devices of protection type "increased safety" (EExeT5) are used.

Finally, it is also possible to take measures to prevent the core pipes and pipe sockets from becoming statically charged.

Examples of embodiments of the invention will now be explained in more detail with reference to the drawing .

Figure 1: a schematic partial cross-section through a heating device according to the invention;

Figure 2: a schematic side view of an end part of a

core pipe on which a connection clamp is arranged., and

Figure 2a: another type of electrical connection;

Figure 3: a schematic cross-section through the area

adjacent core tubes and pipelines connected by sleeves and an electrical connecting cable;

Figure 4: partial cross-section of a preferred electrical connection option for heating the heating conductors and

Figure 5: a side view of an insulating layer in the form of two half-shells;

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- 6 - 19.Cl.1990

Figures 6 and 7 j schematic partial views of alternative

Formations of core tubes equipped with heating conductors.

Figure 1 where int. the device is a composite eye-&bgr;&Tgr;»

coaxially arranged pipes, namely the core pipe 1 and the jacket pipe 3. The heating conductor 2 is wound spirally along the outer jacket of the core pipe 1 in the form of a flat strip and fixed, for example, by gluing. The space between the core pipe 1 with the heating conductor 2 on the one hand and the jacket pipe 3 is essentially completely filled by the insulating layer 4. This can be done, for example, by foaming plastic foam into the space between the two pipes 1 and 3 or by inserting pipe segments made of thermally insulating and, expediently, electrically insulating foam, designed as half-shells 4a, 4b as shown in Figure 5. The main task of the insulating layer 4 is to keep the heat loss radially outside the core pipe 1 as low as possible.

The core tube 1 is expediently made of glass fiber reinforced plastic (GRP), from which, for example, pipes of several meters in length are made using the filament winding process, which are characterized by great stability. However, the invention is not limited to this; for example, plastics reinforced with carbon fibers can also be used. It is also advisable to incorporate substances into the material of the core tube 1 that reduce the thermal conductivity resistance, so that the heat generated by the heating conductors 2 on the outer surface of the core tube 1 can be quickly passed through the core tube 1.

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its inner surface if a heating function is to be fulfilled there. if

The jacket pipe 3 is expediently made of polyethylene (PE), while the insulating layer 4 is expediently made of polyurethane foam.

In order to assemble a pipeline from several such pipe composite systems as shown in Figure 1 and to ensure that electrical voltage can be applied to the heating conductor 2, it is recommended to place a connection clamp 5 made of flexible and electrically conductive material, such as copper, that essentially completely surrounds the circumference of the outer surface of the core pipe 1 in such a way that its radial inner surface comes into good electrical contact with the band-shaped heating conductor 2.

According to Figure 2, such a connection clamp 5 is provided with protruding flanges 5a at the outer ends, so that the connection clamp 5 can be reduced in diameter by pressing the two flanges 5a together with the aid of the locking screw 6 and can be firmly clamped onto the core tube 1. A contact element 17 made of electrically conductive material is connected to the locking screw 6. An extension designed as a clamping lug 17a is clamped between parts of the electrically conductive locking screw 6, while the protruding part 17 can be designed in the manner of a sleeve into which an electrical connecting line 16, for example a bare copper wire, can be inserted and, under certain circumstances, soldered. The contact element is then designed in the form of a so-called "cable lug".

According to Figure 2a, the end 2c of the heating conductor

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2 of one core tube 1 is detached from its original position 2' shown in broken lines from the core tube 1, placed overlappingly on the earth 2c of the stimulus conductor 2 of the adjacent core tube 1 and soldered or welded there to it.

According to Fig. 3 , such a connection clamp is arranged in the area of the end parts 1b of the core tubes 1 at those points where heating conductors 2 are located. The parts of the end parts 1b closest to the end faces 1a of the abutting core tubes 1 can be freed of heating conductors 2 in order to mechanically connect the two end parts 1b by means of a pipe sleeve, which is expediently made of the same material as the core tubes 1. In order to provide sufficient hold, it is recommended to push the pipe sleeve 7 onto the respective front ends of the core tubes 1 by an amount which corresponds approximately to the diameter of the core tubes 1. The electrical connecting line 16 then establishes the electrical connection between the connection clamps 5 of the adjacent core tubes 1 and their heating conductors 2 around and along the pipe sleeve 7, as shown in Fig. 3. With this connection technique, however, the jacket pipes 3 and the insulating layers 4 of the adjacent pipe composite systems do not collide. The axial space between them is filled with insulating material 9, while the pipe ends 8a of an external sleeve 8, which is preferably made of PE, are placed over the pipe ends 3a of the jacket pipes 3. The thermoplastic PE material of the external sleeve 8 in the area of the pipe ends 8a is thermally welded to the material of the jacket pipe in the area of the pipe ends 3a. The insulating material 9 can also be made of PU foam, mineral wool or other material with good thermal conductivity. From the outside, the observer sees a relatively smooth pipe system, although there is a continuous electrical cable inside it.

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connecting train is established.

In order to establish the electrical connection to the outside of the pipe system and to connect the heating conductors to the electrical supply line, it is recommended, as shown in Figure 4, to lead the all-flat connecting line 16 out of the pipe system in such a way that the exposed part of the electrical connecting line 16 is surrounded by a silicone layer and is additionally covered with an insulating oil protection hose (') . The electrical connecting line 16 then leads as a connecting cable 11 to electrical connection elements of the connection box 12, the housing of which is expediently made of plastic and which is equipped with two clamps for connection in this design. For explosion-proof systems, the junction box is equipped with a partition plate 14 which divides the junction box 12 into two compartments, in one of which connection terminals 15 for temperature sensors can be arranged.

Core pipes can also be connected to one another by gluing, welding, coupling or a combination of these.

⁽ All materials that come into contact with the live parts are excellent electrical insulators, while the connection points between the individual units, in particular between the radially outer jacket pipes 3 and outer sleeves 8, are well sealed against the ingress of gases, in particular by welding, so that the device can also be used in areas where there is a risk of explosion.

In a preferred embodiment according to Figure 1, the following dimensions of the individual units are selected:

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Core tube 1: GRP

Outside diameter 114 mm
Jacket pipe 3: PE

Inner diameter: approx. \ 90 nm
Outside diameter: 200 nrn

According to Figure 6, parallel heating strips 2a are glued to the outer casing Ix of the core tube 1 in its longitudinal direction, while the outer casing of the core tube 1 of Figure 7 is completely surrounded by a thin casing 2b made of aluminum; this tube or this tube made of aluminum foil is heated by the electric current flowing along in the longitudinal direction I and thus prevents undesirable heat radiation from the core tube 1 to the cooler environment.

Claims (1)

1. Device for transporting media by means of thermally insulated pipes, in which the medium can be guided along the length of a core pipe which is at least largely surrounded by a thermal insulation layer, characterized in that that a band-shaped or tubular heating conductor (2; 2a; 2b) made of electrically conductive material that heats up due to the electrical current conduction is applied to the core tube (1). 2. Device according to claim 1, characterized in that the heating conductor (2) is wound helically around the core tube (1). 3. Device according to claim 1, characterized in that the heating conductor is designed in the form of several flat strips (2a) running parallel to the core tube (1) and along the latter. - 2 - 10.01.1990 4. Device according to claim 1, characterized in that the heating conductor is arranged as a tubular thin jacket (2b) on the core tube (1). 5. Device according to one of the preceding claims, characterized in that the thermal insulation layer (4) is arranged between the core tube (1) and a jacket tube (3) radially surrounding the core tube (1) and the insulation layer (4). 6. Device according to one or more of the preceding claims, characterized in that the core tube (1) and/or the insulating layer (4) consists essentially of electrically insulating material on which the heating conductor (2) is applied. 7. Device according to claim 6, characterized in that the insulating layer (4) consists of foam. 8. Device according to claim 6 or 7, characterized in that the insulating layer (4) is composed of shell bodies (4a _f 4b) designed in cross section as ring sectors. 9. Device according to one or more of the preceding claims, characterized in that an electrically conductive connection clamp (5) is applied to the end part (Ib) of the core tube (1) in electrical connection with the heating conductor (2) and is provided with a contact - 3 - 10.01.1990 organ (17) for connecting an electrical connecting line (16) is provided or connectable. , 10. Device according to claim 9, characterized, that the connecting line (16) has two consecutive Core tubes (1) are electrically connected. 11. Device according to one or more of the preceding ( } claims, characterized in that one end (2c) of band-shaped heating conductors (2) is lifted off from the relevant core tube (1) and is electrically connected in an overlapping manner to one end (2c) of the heating conductor (2) of an adjacent core tube (1). 12. Device according to one or more of the preceding claims, characterized in that successive core tubes (1) are mechanically connected by a pipe sleeve (7) placed on their end parts (Ib). 13. Device according to one of claims 10 to 12, characterized in that that the connecting line (16) is guided radially outside the pipe socket (?) along its length, 14. Device according to one or more of the preceding claims, characterized, that the end parts (3a) of the jacket pipes (3) are connected by means of a connected to this external sleeve (8) and - 4 - 10.01.,1990 that the space between the pipe socket (7) and the outer socket (8) is substantially filled with thermal insulating material (9). 15. Device according to one or more of the preceding claims, characterized in that the electrical connecting line (16) serves for connection to an electrical connection box (12) or an electrical terminal board which can be connected to an electrical voltage source. 16. Device according to one or more of the preceding claims, characterized by a monitoring device, of which a thermal sensor is arranged in the area of the core tube (1).