GB2137059A - Electrical Heating Method - Google Patents
Electrical Heating Method Download PDFInfo
- Publication number
- GB2137059A GB2137059A GB08406398A GB8406398A GB2137059A GB 2137059 A GB2137059 A GB 2137059A GB 08406398 A GB08406398 A GB 08406398A GB 8406398 A GB8406398 A GB 8406398A GB 2137059 A GB2137059 A GB 2137059A
- Authority
- GB
- United Kingdom
- Prior art keywords
- electrode
- polyester composition
- conducting
- metal
- pipe
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims abstract description 17
- 238000010438 heat treatment Methods 0.000 title claims abstract description 13
- 229920000728 polyester Polymers 0.000 claims abstract description 36
- 239000000203 mixture Substances 0.000 claims abstract description 30
- 239000002184 metal Substances 0.000 claims abstract description 29
- 229910052751 metal Inorganic materials 0.000 claims abstract description 29
- 238000000576 coating method Methods 0.000 claims abstract description 9
- 239000011248 coating agent Substances 0.000 claims abstract description 8
- 239000006229 carbon black Substances 0.000 claims description 8
- 239000005030 aluminium foil Substances 0.000 claims description 7
- 239000003365 glass fiber Substances 0.000 claims description 6
- 239000011810 insulating material Substances 0.000 claims description 4
- 229920001225 polyester resin Polymers 0.000 description 6
- 239000004645 polyester resin Substances 0.000 description 6
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- MMEDJBFVJUFIDD-UHFFFAOYSA-N 2-[2-(carboxymethyl)phenyl]acetic acid Chemical compound OC(=O)CC1=CC=CC=C1CC(O)=O MMEDJBFVJUFIDD-UHFFFAOYSA-N 0.000 description 1
- WFUGQJXVXHBTEM-UHFFFAOYSA-N 2-hydroperoxy-2-(2-hydroperoxybutan-2-ylperoxy)butane Chemical compound CCC(C)(OO)OOC(C)(CC)OO WFUGQJXVXHBTEM-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000009730 filament winding Methods 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/42—Heating elements having the shape of rods or tubes non-flexible
Landscapes
- Lining Or Joining Of Plastics Or The Like (AREA)
Abstract
An electrical heating method suitable for heating metal pipes or tanks comprises coating the metal surface to be heated with a conducting polyester composition, positioning an electrode in electrical contact with the conducting polyester such that the electrode and metal surface are separated by the conducting polyester composition and applying an electrical current between the electrode and the metal surface. The invention includes a metal pipe adapted to be heated by the method.
Description
SPECIFICATION
Electrical Heating Method
The present invention relates to an electrical heating method suitable for heating metal pipes or tanks.
Crude oils of high viscosity or having a high wax content and petroleum products such as fuel oils and bitumen may be substantially solid, or at least very viscous, at ambient temperatures. In order to transport such viscous hydrocarbons by pipeline, it may be necessary to heat the hydrocarbon. If the pipeline is long or passes through an area of low ambient temperature such as arctic areas or under water, it may be necessary to provide reheating stations or otherwise provide further heat to the hydrocarbon.
According to the present invention an electrical heating method suitable for heating metal pipes or tanks comprises coating the metal surface to be heated with a conducting polyester composition, positioning an electrode in electrical contact with the conducting polyester composition such that the electrode and the metal surface are separated by the conducting polyester composition and applying an electrical current between the electrode and the metal surface.
Conducting polyester compositions are known.
For example, polyesters containing 2 to 8% by weight of electrically conducting carbon black dispersed throughout the composition are disclosed in UK Patent GB 2018 780B and published European Patent Application 0099717 discloses conducting polyester compositions containing from 0.1 to 8% by weight of carbon black dispersed throughout the composition by high shear mixing.
The method according to the present invention may be used in various heating applications where the surface to be heated is a metal which can be used as an electrode. The method is particularly suitable for heating metal pipes.
The invention includes a pipe adapted to be electrically heated according to the method described above, the pipe comprising a metal pipe coated with a cured conducting polyester composition and an electrode which is in electrical contact with, but separated from the metal pipe by, the conducting polyester composition, the metal pipe and the electrode being connectabie to an electrical supply.
The electrode may be of any electrically conducting material such as metal or carbon and may be of any suitable size or shape. The electrode may conveniently be in the form of a relatively thin metal sheet e.g. aluminium foil, or a braided metal tape.
The metal surfaces to be heated may be coated with the conducting polyester using known methods. For example, the polyester may be moulded directly onto the metal surface. The polyester may be simply applied to the surface and cured or may be injected into a mould and then cured. Reinforcing fibres such as glass fibres may be included in the conducting polyester composition. The fibres may be in the form of fabric, filament winding rovings, chopped strand mat or woven rovings. The fibres may be placed on the metal surface and then coated with the polyester composition or they may be impregnated with the resin before being applied to the metal surface.
The electrode may be attached to the cured conducting polyester but is preferably moulded into it by positioning the electrode at or just below the surface of the conducting polyester prior to curing. The electrode may be protected by an external coating which may be of the conducting polyester composition but is preferably an insulating material.
Conventinal thermal and/or electrical insulating materials may be used in the method according to the present invention. A non-conducting polyester composition, i.e. one which does not contain electrically conducting carbon black, may be used as a thermal and electrical insulating material.
The polyester may be the same as used in the conducting polyester composition.
The invention is illustrated with reference to the following example.
Example
A conducting polyester composition was prepared by uniformly dispersing 1% by weight of an electrically conducting carbon black, supplied by Phillips Petroleum under the trade mark XE-2, in a commercially available general purpose orthophthalic polyester resin sold by BP
Chemicals under the trade name Cellobond
A262/249. (Cellobond is a registered trade mark).
The polyester and carbon black were mixed in a low shear mixer until the carbon black was wetted with the polyester resin. The mixture was subjected to high shear mixing for 5 minutes and then allowed to stand for 15 minutes under an absolute pressure of 2.7 x104 Pa.
0.5 g of a 6% solution of cobalt octoate and
1 2g of a 50% solution of methyl ethyl ketone peroxide were added to 600g of the mixture of polyester resin and carbon black. The conducting polyester composition was then used to impregnate glass fibre rovings.
The impregnated glass fibre rovings were wound around a 500 mm long stainless steel pipe which had an internal diameter of 25 mm and an outside diameter of 33 mm. Two passes of 2400 tex glass fibre were wound onto the outside of the tube. 0.15 mm thick aluminium foil was wrapped
around the fibre reinforced conducting coating to form the electrode. Glass fibre rovings
impregnated with non-conducting polyester resin
were then wrapped around the aluminium foil to
provide an insulating coating. The polyester resin
was Cellobond A262/249, i.e. the same resin as
used to prepare the conducting polyester
composition, and the same accelerator and
initiator were used. The outer coating of fibre
reinforced non-conducting polyester not only provides electrical insulation but also protects the thin aluminium foil from accidental damage.
The pipe was placed in an oven at 800C for 4 hours to cure the polyester resin coatings. After cooling, the ends of the pipe were trimmed so that the length was reduced to 400 mm. The outside diameter of the coated pipe was 45 mm.
A small section of the outer insulating coating was removed and a wire connected to the aluminium foil electrode. A second wire was connected to the stainless steel pipe. The resistance between the aluminium foil and the stainless steel pipe was determined to be approximately 8 k.
One end of the pipe was stoppered, the pipe stood on that end and then filled with silicone oil.
A thermometer was immersed in the oil. The wires attached to the aluminium electrode and the stainless steel pipe were connected to a variable a.c. electrical supply. The voltage of the supply was increased step wise during the run and the temperature recorded. The results given in Table 1 indicate how the rate of rise of temperature varies with voltage. The electrical supply was disconnected after 13 minutes but the temperature continued to rise for a time due to the lag in the system. The current passing at 1 OOv was 1.4A.
TABLE 1
Time Voltage Oil Temperature (min) (V) ( C) O 40 27 1 40 27 2 40 27.5 3 40 28 4 40 28.5 5 40 29 6 40 29 7 - 60 30 8 60 30.5 9 60 31
10 60 32 11 100 34.5 12 100 39 13 100 46 14 - 54 15 - 59 16 - 60 17 - 61 18 - 61
Claims (8)
1. An electrical heating method suitable for heating metal pipes or tanks comprises coating the metal surface to be heated with a conducting polyester composition, positioning an electrode in electrical contact with the conducting polyester composition such that the electrode and metal surface are separated by the conducting polyester composition and applying an electrical current between the electrode and the metal surface.
2. A method as claimed in claim 1 in which the conducting polyester composition comprises a polyester containing from 0.1 to 8% by weight of carbon black dispersed throughout the composition by high shear mixing.
3. A method as claimed in either of claims 1 or 2 in which the electrode is aluminium foil.
4. A method as claimed in any of claims 1 to 3 in which the conducting polyester composition is reinforced with glass fibre.
5. A pipe adapted to be electrically heated by the method of any of claims 1 to4 comprising a metal pipe coated with a cured conducting polyester composition and an electrode which is in electrical contact with, but separated from the metal pipe by, the conducting polyester composition, the metal pipe and the electrode being connectable to an electrical supply.
6. A pipe as claimed in claim 5 coated with an insulating material which is a non-conducting polyester composition.
7. An electrical heating method substantially as described in the example.
8. A pipe, which is adapted to be electrically heated, substantially as described in the example.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08406398A GB2137059A (en) | 1983-03-26 | 1984-03-12 | Electrical Heating Method |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB838308383A GB8308383D0 (en) | 1983-03-26 | 1983-03-26 | Heatable pipelines |
| GB08406398A GB2137059A (en) | 1983-03-26 | 1984-03-12 | Electrical Heating Method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8406398D0 GB8406398D0 (en) | 1984-04-18 |
| GB2137059A true GB2137059A (en) | 1984-09-26 |
Family
ID=26285633
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08406398A Withdrawn GB2137059A (en) | 1983-03-26 | 1984-03-12 | Electrical Heating Method |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2137059A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2182413A (en) * | 1985-11-04 | 1987-05-13 | Lee Fisher Robinson | Protecting pipelines and tanks |
| GB2203213A (en) * | 1987-04-02 | 1988-10-12 | Donald Edgar Bromley | Frost protection system for water pipes |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB654128A (en) * | 1948-09-17 | 1951-06-06 | Dunlop Rubber Co | Improvements in electrically heated vessels |
| GB1396590A (en) * | 1971-09-27 | 1975-06-04 | Reuter Maschinen | Electrically heatable area heating elements |
| GB1572880A (en) * | 1976-04-06 | 1980-08-06 | Daikin Ind Ltd | Tube |
-
1984
- 1984-03-12 GB GB08406398A patent/GB2137059A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB654128A (en) * | 1948-09-17 | 1951-06-06 | Dunlop Rubber Co | Improvements in electrically heated vessels |
| GB1396590A (en) * | 1971-09-27 | 1975-06-04 | Reuter Maschinen | Electrically heatable area heating elements |
| GB1572880A (en) * | 1976-04-06 | 1980-08-06 | Daikin Ind Ltd | Tube |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2182413A (en) * | 1985-11-04 | 1987-05-13 | Lee Fisher Robinson | Protecting pipelines and tanks |
| GB2182413B (en) * | 1985-11-04 | 1989-12-06 | Lee Fisher Robinson | Improvements relating to protection of pipelines and fluid containers |
| GB2203213A (en) * | 1987-04-02 | 1988-10-12 | Donald Edgar Bromley | Frost protection system for water pipes |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8406398D0 (en) | 1984-04-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |