Device for transporting a medium and assembly method

Abstract

A device for transporting a medium includes at least one channel which extends in an axial direction and through which the medium is guided. The channel is enclosed by an electrically conductive inner envelope that is connected to a first potential equalization conductor. An electrically conductive outer envelope is provided between the channel and an electrically conductive outer casing and is connected to an electrically conductive second potential equalization conductor. Arranged between the channel and the outer envelope is an electrically insulating intermediate layer which is produced from heat-insulating material.

Claims

1. A device for transporting a medium, comprising: a first potential equalization conductor: an electrically conductive inner envelope configured to enclose a channel which extends in an axial direction for passage of a medium, said inner envelope being connected to the first potential equalization conductor; an outer casing configured to be electrically conductive; an electrically conductive second potential equalization conductor; an electrically conductive outer envelope provided between the channel and the outer casino and connected to the second potential equalization conductor: an electrically insulating intermediate layer arranged between the channel and the outer envelope and produced from heat-insulating material, an end piece and an electrically conductive cap placed upon the end piece, and an electrically conductive shrink tube applied to the electrically conductive cap and to at least one area of the outer casing to secure the cap and to electrically conductively connect the electrically conductive cap to the outer casing.

2. The device of claim 1, wherein the outer casing is made of thermoplastic resin with 1 to 6 wt % carbon nanotubes.

3. The device of claim 1, wherein the outer casing is made of 4 to 6 wt % carbon nanotubes and thermoplastic urethane.

4. The device of claim 1, wherein the electrically conductive cap is made of polytetrafluoroethylene (PTFE).

5. The device of claim 1, wherein the channel is produced from thermoplastic resin.

6. The device of claim 1, wherein the channel is produced from a metal alloy.

7. The device of claim 1, further comprising a heating device arranged inside the channel for controlling a temperature of the medium.

8. The device of claim 1, wherein the outer envelope is configured as a metal foil.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

(2) FIG. 1 is a sectional view of a device for transporting a medium in accordance with the present invention;

(3) FIG. 2 is a top view of a first end of the device according to FIG. 1;

(4) FIG. 3 is a top view of a second end of the device according to FIG. 1;

(5) FIG. 4 a perspective view of the device according to FIG. 1 at a first end; and

(6) FIG. 5 a perspective view of the device according to FIG. 1 at a second end.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments may be illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

(8) Turning now to the drawing, and in particular to FIG. 1, there is shown a sectional view of a device, generally designated by reference numeral 2, for transporting a medium in accordance with the present invention. The device 2 is configured as an analysis line and serves to transport gas samples from a sampling site to an analysis device. Distances of several hundred meters can hereby be crossed. In order to transport the gas in an axial direction or opposite to the axial direction of the device 2, two tubular channels 8 or gas conductors are provided that are composed of PE material. A heating band 14 is provided inside the channels 8 for heating of the gas. The heating band includes a heating band element 20 and two heat conductors 26 which are embedded in the heating band element 20. Currently preferred is a configuration of the heating band 14 as an electrical self-regulating heating band. The heating band element 20 is advantageously composed of conductive polymers that are mixed with conductive carbon black. The output of the heating band 14 is between 16 W/m and 64 W/m at 10? C. The current required to heat the medium depends on a length of the heating band 14.

(9) Alternatively, a heating band can also be provided in which a temperature is regulated via a control and regulation unit. In this case, temperature sensors are mounted on the outside of the internal tube in order to determine the temperature. A maximum temperature can be limited, and the temperature is also regulated. The maximum temperature acts hereby effectively as a constraint on regulation, i.e. it ensures that the measured maximum temperature is not exceeded. In order for this temperature to correspond to the maximum temperature actually occurring, the temperature sensor(s) should be placed in the areas of highest ambient temperatures. For applications in which the temperature should not drop below a minimum level, the temperature sensor should be installed at the site with the lowest ambient temperature.

(10) A limiter is normally set to the maximum (or minimum) allowable temperature. Two temperature sensors can also be used, with one temperature sensor being used to limit the temperature to a minimum and the other temperature sensor being used to limit the temperature to a maximum. Such a configuration is suitable for zones with sharply fluctuating ambient temperatures. The regulation process is then carried out with the proviso that the temperature should not rise above and/or drop below the maximum and/or minimum temperature.

(11) The device 2 includes an outer casing 32 that shields the inner components from external influences, damage, stress, etc. This allows the device 2 or the analysis line to be used in potentially explosive areas, in particular IIC areas. For this purpose, the outer casing 32 or the material from which it is produced is configured to be electrically conductive or dissipative. In accordance with a non-limiting embodiment, the material of the outer casing 32 is produced from extruded thermoplastic urethane with a homogeneously distributed content of 1 to 6 wt % CNTs, in particular 4 wt % CNTs. The device 2 further has components which, particularly in combination with the conductive outer casing 32, allow effective and rapid dissipation of an electric charge, and thus prevent the occurrence of ignition sparks even in IIC areas. With a content of 2 wt % CNTs, resistance values of 100 k?.Math.m or 50 k?.Math.m were measured at voltages of 500 V and 1000 V.

(12) At 4 wt % CNTs, values of 10 k?m/5 k?.Math.m are measured at 500 V/1000 V. The resistance is even lower with higher CNT content.

(13) For this purpose, the device 2 has an inner envelope 38, which may be configured as aluminium foil. Viewed in a radial direction 4, an outer envelope 50 is provided inside the outer casing 32 and outside the inner envelope 38 and may also be configured as aluminium foil. The inner envelope 38 and the outer envelope 50 extend in the shape of a cylinder along the axial direction of the device 2. The inner envelope 38 and the outer envelope 40 are each connected via potential equalization conductors 58, 56 to an earthing system, such that the two envelopes 38, 50 have a same electrical potential, and this potential is identical to the earth potential, such that there is no potential difference with respect to the earth. Thus, when electrical charges collect on one of the two envelopes 38, 50, potential equalization with respect to the earth takes place via the potential equalization conductors 58, 56, respectively.

(14) In this way, sparks or lightning-like electrical discharges are prevented. Such discharges might occur, for example, if electrical charges were to separate in channel 8, causing it to be electrically charged, and if no potential equalization to the outer casing 32 were to occur. In particular, the combination between the outer casing 32 and the outer envelope 50 which is connected to the outer casing 32 in an electrically conductive manner and lies radially outside the outer casing 32, allows effective and reliable dissipation of electric charges.

(15) Provided between the outer casing 32 and the outer envelope 50 is a layer 62 which surrounds the outer envelope 50. Currently preferred is a layer 62 made of a PETP film. For production reasons, the layer 62 is provided to prevent damage to the outer envelope 50 during production of the analysis line and therefore virtually functions as a protective layer. It provides no added technical function in the non-limiting example, shown here.

(16) Viewed in a radial direction 44, an intermediate layer 68 of thermo-fleece is arranged between the inner envelope 38 and the outer envelope 50. The intermediate layer 68 thus serves a dual purpose: It electrically insulates the two envelopes 38, 50 and it provides thermal insulation of the heated channels 8 such that energy for heating thereof can be saved. In addition, the channels 8 are shielded from external temperature influences such that the fluctuations in temperature of the fluid are reduced.

(17) The device 2 can be assembled on-site, e.g. when it is actually being laid, i.e. the device 2 can be in particular adjusted in length. FIG. 2 shows a top view of the device 2 according to FIG. 1 at a first end 82 or beginning, which corresponds to the sample end. An end piece of the device 2 is formed at the end 82, with a cap 80 or end cap being slipped over or placed on the outer casing 32. The cap 80 is advantageously produced from PTFE. A shrink tube 86 composed of conductive material is shrink-fitted over the cap 80 and over at least one area of the outer casing 32. In this way, the end 82 or end piece is protected, and at the same time, use of conductive materials for the cap 80 and shrink tube 86 prevents formation of ignition sparks.

(18) FIG. 3 shows the device 2 at a second end 92 that corresponds to the analysis end. At this end are also provided a cap 80 and a shrink tube 86, both of which are composed of electrically conductive material. Moreover, a power supply 100 is guided out from the cap 80 and shrink tube 86.

(19) As described above, the two ends of the device 2 (sample end, analysis end) are advantageously provided with end caps. As an alternative, provision may also be made for shrinkable end caps to effect protection against penetration of moisture and dust.

(20) FIGS. 4 and 5 show perspective views of the device 2 at the first end 82 or second end 92, respectively. In the non-limiting example, shown here, the device 2 is configured as a tube bundle wound or rolled onto a cable drum, which for laying is then carefully unwound from the drum. Optionally, the analysis line is then cut off or separated from the drum. The above-described caps 80 or shrink tubes 86 are then placed or shrink-wrapped onto the two resulting ends.

(21) Both ends must be sealed (e.g. with silicone) to protect against penetration of moisture, dust and possibly cross-contamination with explosive gases. This sealing of the ends makes the device gas-tight at the ends, thus preventing possible cross-contamination with explosive gases.

(22) While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

(23) What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: