EXTENSION OF ELECTRICALLY TRACED TUBING BUNDLES

Abstract

An electrically traced tubing bundle includes one or more tubes and an electric heating element, encased in insulation and covered by a jacket. The heating element is given a discontinuity at a point intermediate the ends of the tubing bundle. A power extension supply wire extends from a powered end of the bundle to the discontinuity and is connected to the remote portion of the heating element. At the discontinuity, the end of the near portion of the heating element is terminated. The end of the remote portion of the heating element is terminated at the remote end of the tubing bundle.

Claims

1. An electrically traced tubing bundle having a near end and a remote end, the tubing bundle comprising at least one tube, an electric heating element extending generally parallel to the at least one tube, insulation encasing the at least one tube and the electric heating element, and a jacket surrounding the insulation, the heating element, and the at least one tube, the tubing bundle further comprising a discontinuity in the heating element intermediate the ends of the tubing bundle, the discontinuity defining a near portion of the heating element and a remote portion of the heating element, and a power extension supply extending from the near end of the tubing bundle to the discontinuity and being connected to the remote portion of the heating element at the discontinuity.

2. The tubing bundle of claim 1 wherein the power extension supply extends internally of the jacket from the near end of the tubing bundle to the discontinuity.

3. The tubing bundle of claim 1 wherein the power extension supply extends externally of the jacket from the near end of the tubing bundle to the discontinuity.

4. The tubing bundle of claim 1 wherein the heating element includes a lead extending out of the near end of the tubing bundle.

5. The tubing bundle of claim 4 wherein the lead and a near end of the power extension supply are connected to a single electric source in a junction box.

6. The tubing bundle of claim 5 wherein a single power controller controls electric power fed to the near portion and the remote portion of the electric heating element.

7. The tubing bundle of claim 1 wherein the heating element is chosen from the group consisting of self-regulating heaters, power limiting heaters, and constant power density heaters.

8. The tubing bundle of claim 1 wherein at least one of the near portion of the heating element and the far portion of the heating element has a length of at least one hundred feet.

9. The tubing bundle of claim 1 wherein both the near portion of the heating element and the far portion of the heating element have an individual length of at least ten feet.

10. A method of extending the operational length of an electrically traced tubing bundle fed from an electrical source at a near end of the tubing bundle, the method comprising heating an extension of the tubing bundle with a heater fed by a power extension supply electrically connected to the electrical source.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0016] In the accompanying drawings which form part of the specification:

[0017] FIG. 1 is a schematic view of an illustrative embodiment of an electrically traced tubing bundle in accordance with the present invention, carrying out a method of the invention.

[0018] FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1.

[0019] FIG. 3 is a schematic view corresponding to FIG. 1 of a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0020] The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

[0021] As shown in FIGS. 1 and 2, in accordance with one illustrative embodiment, a pre-traced tubing bundle 1 includes a near end 3 and a remote end 5, the tubing bundle comprising a first tube 7 and a second tube 9, an electric heating element (tracer cable) 11 extending generally parallel to the tubes 7 and 9, insulation 13 encasing the tubes 7 and 9 and the electric heating element 11, and a jacket 15 surrounding the insulation 13, the heating element 11, and the tubes 7 and 9. The heating element 11 is energized from a power supply 17 through a circuit breaker 19, a controller 21, and a power connector 23 at the near end 3 of the tubing bundle 1. A temperature sensor 25 is placed inside the insulation 13 toward the near end 3 of the bundle 1 and is connected to the controller 21 to modulate power supplied to the heating element 11 and maintain at least a desired temperature of the heater 11 and tubes 7 and 9.

[0022] In this embodiment, the tubing bundle 1 is an O'Brien TRACEPAK SU-F3G2S-JN5/829/1 M/7-78933 sample line, commercially available from O'Brien/Ametek. As is known to those skilled in the art from this designation, the first tube 7 is a 0.375 (9.5 mm) tube made of 316 stainless steel, the second tube 9 is a 0.25 (6.35 mm) tube made of perfluoroalkoxy (PFA), the heater 11 is a Raychem 5VPL2-CT power limiting tracer cable, commercially available from nVent Raychem, Redwood City, Calif., and described in Tyco/Thermal Controls bulletin H56925, dated August 2007. The insulation 13 is made of fiberglass tape. The jacket 15 is made of TPU plastic. The tubing bundle 1 is designed to maintain a temperature of 60 F. (16 C.) at a low ambient design temperature of 20 F. (7 C.). The power supply 17 provides 208-volt power through a 30-amp circuit breaker 19. The power connector 23 provides power to the tracer bus wires. The tracer cable 11 is end terminated at 26. As thus far described, the tubing bundle 1 is conventional.

[0023] The illustrative tubing bundle has a maximum published circuit length of 659 feet (201 meters). The illustrative application, however, requires a heated tubing bundle extending 829 feet (253 meters). The present invention allows extension of the bundle to this length without requiring a separate power supply and circuit breaker, or an additional controller 21 and temperature sensor 25.

[0024] In accordance with this embodiment of the invention, the power supply 17 is split at a junction box 27 into a lead connected to the power connector 23 at the near end 3 of the tubing bundle 1 and a power extension supply or jumper 29. The power extension supply 29 is sized according to the circuit requirements and extension length. The power extension supply 29 extends 170 feet (52 meters) along the exterior of the tubing bundle 1. The 170-foot extension supply length could be reduced if the line length is cut for installation. At that point, at least the powered conductor of the heater 11 is broken and its near end is provided with an end termination 31, which is illustratively outside the tubing bundle 1. The far end of the break in the heater conductor is attached to the power extension supply 29 by a power connection 33 extending through the jacket 15 and insulation 13. The remote 659 feet (201 meters) is heated through the power extension supply 29.

[0025] This embodiment of the invention allows the entire length of the tubing bundle to be heated with minimal modification of the bundle or its power supply.

[0026] In accordance with a second embodiment of the invention, shown in FIG. 3, a tubing bundle 101 includes tubing 107 and a tracer 111. In this embodiment, the self-regulating tracer 111 is relied upon to keep the temperature inside the tubing bundle 101 at a constant temperature, and the controller and temperature sensor are eliminated. As in the first embodiment, the tracer 111 is connected to power supply 17 through a single circuit breaker 19, a junction box 27, and a power connector 23 at a near end 103 of the tubing bundle 101. The tracer 111 is broken and the near end of the tracer 111 is connected to an end termination 131. The far end of the tracer 111 is attached through a power connector 133 to a power extension supply 129. At a far end 105 of the tubing bundle 101, the far end of the tracer 111 is connected to end terminal 26.

[0027] In this embodiment, the power extension supply 129 is encased in the insulation and jacket of the tubing bundle 101, rather than running outside the bundle. The end termination 131 and the power connector 133 are optionally encased inside the jacket of the tubing bundle 101. This arrangement requires that the entire installation be pre-engineered and custom manufactured, but produces a product with fewer external parts and potentially with fewer openings to be sealed in the bundle's jacket.

[0028] Numerous variations, within the scope of the invention, will occur to those skilled in the art.

[0029] All patents, patent applications, and literature mentioned herein are hereby incorporated by reference.