Mineral insulated cable having reduced sheath temperature

Patent metadata

Field	Value
Publication number	US-2019021138-A1
Application number	US-201816128344-A
Country	US
Kind code	A1
Filing date	Sep 11, 2018
Priority date	Jul 5, 2012
Publication date	Jan 17, 2019
Grant date	—

Abstract

A mineral insulated heating cable for a heat tracing system. The heating cable includes a sheath having at least a first, and optionally a second layer, wherein the thermal conductivity of the second layer is greater than a thermal conductivity of the first layer. In addition, the first and second layers are in intimate thermal contact. The heating cable also includes at least one heating conductor for generating heat and a dielectric layer located within the sheath for electrically insulating the heating conductor, wherein the sheath, heating conductor and dielectric layer form a heating section. In addition, the heating cable includes a conduit for receiving the heating section. Further, the heating cable includes a cold lead section and a hot-cold joint for connecting the heating and cold lead sections. In addition, a high emissivity coating may be formed on the first layer.

First claim

1 . A mineral insulated heating cable for a heat tracing system, comprising:
a sheath; at least one heating conductor located within the sheath; a dielectric layer located within the sheath for electrically insulating the heating conductor, wherein the sheath, heating conductor and dielectric layer form a heating section; and a conduit, wherein a full length of the heating section is located within the conduit, the conduit defining an internal cavity sized to create a gap separating the heating section from an interior surface of the conduit along the full length of the heating section so that heat generated by the heating section is transferred to the conduit by radiation.

2 . The mineral insulated heating cable of claim 1 , wherein the conduit is corrugated.

3 . The mineral insulated heating cable of claim 1 , wherein a surface area of the interior surface of the conduit is at least approximately 2.5 times greater than an outer surface area of the heating section.

4 . The mineral insulated heating cable of claim 1 , wherein the heating section is sealed within the conduit via fittings coupled to respective ends of the conduit to provide isolation from environmental conditions.

5 . The mineral insulated heating cable of claim 1 , wherein the sheath includes at least one first layer having a first thermal conductivity and at least one second layer having a second thermal conductivity that is greater than the first thermal conductivity.

6 . The mineral insulated heating cable of claim 1 and further comprising a cold lead section and a hot-cold joint configured to connect the heating and cold lead sections.

7 . The mineral insulated heating cable of claim 6 , wherein the hot-cold joint is located at least partially within the conduit and the cold lead section extends out of the conduit.

8 . The mineral insulated heating cable of claim 1 , and further comprising a high emissivity coating applied to the sheath, the coating having an emissivity value of at least 0.6.

9 . The mineral insulated heating cable of claim 1 , wherein the sheath includes an outer surface that is one of oxidized to form an oxidized layer or subjected to a black anodizing process to form an anodized layer.

10 . A mineral insulated heating cable for a heat tracing system, comprising:
a sheath that includes at least one first layer having a first thermal conductivity and at least one second layer having a second thermal conductivity that is greater than the first thermal conductivity; at least one heating conductor located within the sheath; and a dielectric layer located within the sheath for electrically insulating the heating conductor, wherein the sheath, heating conductor and dielectric layer form a heating section.

11 . The mineral insulated heating cable of claim 10 further including a high emissivity coating formed on the first layer, the high emissivity coating having an emissivity value of at least approximately 0.6.

12 . The mineral insulated heating cable of claim 10 , wherein the first layer is fabricated from Alloy 825.

13 . The mineral insulated heating cable of claim 10 , wherein the second layer is fabricated from copper.

14 . The mineral insulated heating cable of claim 10 , wherein a thickness of the second layer is greater than approximately 10% of a thickness of the sheath.

15 . The mineral insulated heating cable of claim 10 , wherein the first layer is a least approximately 0.002 inches thick.

16 . The mineral insulated heating cable of claim 10 , wherein the mineral insulated heating cable is part of a heat tracing system configured to heat a substrate, the mineral insulated heating cable is spaced apart from portions of the substrate, and further comprising at least one fin in thermal contact with the heating section in an area where the mineral insulated cable is spaced apart from the substrate.

17 . The mineral insulated heating cable of claim 16 , wherein the fin includes a first fin layer having a first thermal conductivity and a second fin layer having a second thermal conductivity that is greater than the first thermal conductivity.

18 . The mineral insulated heating cable according to claim 10 and further comprising a conduit, wherein the heating section is located within the conduit.

19 . The mineral insulated heating cable of claim 18 and further comprising a cold lead section and a hot-cold joint configured to connect the heating and cold lead sections.

20 . The mineral insulated heating cable of claim 19 , wherein the hot-cold joint is located at least partially within the conduit and the cold lead section extends out of the conduit.

Assignees

• Nvent Services Gmbh

Inventors

• Becker Paul
• Ling Fuhua
• Liu Ningli
• White Lawrence Joseph
• Martin Ii Louis Peter
• Finlayson Scott Murray
• Beres James Francis
• Kleinehanding Marcus

Classifications

• H05B3/56

  Heating cables · CPC title

• H05B3/50

  heating conductor arranged in metal tubes, the radiating surface having heat-conducting fins · CPC title

• H05B2203/011

  Heaters using laterally extending conductive material as connecting means · CPC title

• H05B3/02 Primary

  Details · CPC title

• Y10T29/49083

  Heater type · CPC title