GB2244414A

GB2244414A - Heating

Info

Publication number: GB2244414A
Application number: GB9111173A
Authority: GB
Inventors: Victor Cooper
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-05-24
Filing date: 1991-05-23
Publication date: 1991-11-27
Also published as: GB9111173D0; GB9011667D0

Abstract

A heated conduit (3) is used with an oil pipeline (1) so as to heat the oil and thereby lower its viscosity. In one embodiment an electrical conductor (4) inside a conduit 3 is attached to the outside of an existing pipe (1) either by winding or laying it laterally. The conductor (4) has an alternating electric current flowing through it and the electric current generates a magnetic field (5) which heats the wall (30) of conduit 3 by way of dipolar excitation and thus heats pipe (1). In other embodiments the heating element may be laid within the pipe or formed integrally therein. <IMAGE>

Description

HEATING SYSTEM This invention relates to a heating system and more specifically, but not exclusively, it relates to a system for maintaining a fluid or a solid suspension at a substantially constant temperature whilst the fluid or solid suspension is flowing through a transporting conduit.

According to the present invention there is provided a heating system for a conduit comprising an electrical conductor arranged in or proximal to the conduit such that in use an electric current flowing in the conductor causes inductive heating of the conduit.

Preferably the conduit is formed from a material which experiences dipolar excitation in a magnetic field of an electric current. The current is preferably an alternating current. The substance within the conduit may itself be of dipolar nature and heating may therefore be effected directly as it flows through the conduit.

The electrical conductor, which may be an insulated cable transmitting electricity at high voltage may be contained in the conduit which is preferably a pipe. Such an arrangement permits the pipe to be buried or submerged and also permits the substance to be pumped under pressure.

Alternatively the electrical conductor may be fixed to an outside surface of the conduit in such a way that the substance flowing through the conduit is heated from the outside. Several electrical conductors may be arranged around the conduit so that heating may be effected evenly.

The electrical conductor and conduit may be formed as a single unit and attached or connected to a pipe so that an integral inductive heater may be formed. Such an inductive heater may be attached to existing pipes and used as an in-situ heater whilst the pipes are used to transport a substance to be maintained at a constant temperature.

The integral inductive heater may be attached to a pipe, by way of flexible connectors wrapped around the heater conduit and pipe or the heater may rest on suitably adapted supports.

Preferably the heater is supported below the pipe so as to enable convective currents to conduct heat upwards. Different materials may be used to form the pipe and/or the heating conduit depending on heating requirements of the particular situation.

For example a material having a high thermal conductivity may be used to form the conduit in a colder environment or when the liquid inside the pipe does not needto be heated to a high temperature.

Control means may be provided to limit the amount of current which flows along the conductor.

Such control means may be placed at an entry or exit point where the commencement or completion of the heating conduit is situated.

Monitoring devices may be provided at the entry or exit points and/or along the length of the pipe conduit, so that feedback and monitoring of temperatures may be achieved.

Two embodiments of the invention will now be described, by way of example only, and with reference to the accompanying Figures in which: Figure 1 is a sectional view of an inductive heating system shown below a pipe; Figure 2 is a longitudinal section of the arrangement of Figure 1; Figure 3 is a sectional view of an alternative embodiment; and Figure 4 is a longitudinal section of Figure 3 showing monitoring points along the length of the pipe.

Figures 1 and 2 show different views of a heating system 1 for a pipe 2 which has a heating conduit 3 within which an electrical conductor 4 is axially disposed. Lines of Magnetic field 5 emanate co-axially from the heating conduit 3. The lines shown in Figure 1 are for a single instant in time and in a real situation are constantly varying when an alternating current (AC) flows through the conductor 4. The wall 30 of the heating conduit 3 is proximal to the electrical conductor 4 and is of a material which interacts with the induced magnetic field. An example of such a material is one in which molecules in the material, undergo successive polar attraction and repulsion and these molecular interactions give rise to an energy dissipation which is in the form of heat.The heat energy thus produced is transmitted by way of direct conduction to pipe 1 or, by convection currents set-up in the surrounding fluid 40 which may be water, air or air entrapped in a granular material. Liquid 10, contained in the pipe 1 undergoes a temperature rise proportional to with the heat energy received.

The heating conduit 30 may be attached permanently to the pipe 1 by way of a fixing material, straps or clips. These may be intermittant dispersed along the length of the pipe or conduit.

Figures 3 and 4 show transverse and longitudinal sections respectfully through an alternative embodiment to that of Figures 1 and 2.

Pipes 21, 22, 23 and tansporting pipe 28 are all held as a bundle in a carrier, pipe 29. Oil is transported inside pipe 28. Other pipes 21,22,23,24 do not transport the fluids which require heating.

They provide, for example, electro-hydraulic control functions or they transport chemical suppressents to an oil well head. The carrier pipe 29 also contains a gel fill 26 or other void filling and insulating material. The transporting pipe 28 is surrounded by a number of electrical conductors 4A, 4B, 4C and 4D.

The electrical conductors 4A, 4B, 4C and 4D are attached to the transporting pipe 28 by way of straps 33. The transporting pipe 28 transports a fluid 41, which must be maintained at a constant temperature or within a given temperature range and is also held within the main carrier pipe 29.

Sensors 40 are placed at intervals along the length of the transporting pipe 28 and provide feedback signals to a current controller (not shown). The signals are used to increase in decrease the current which passes along the conductors 4.

Another problem encountered in pipelines transporting gas has been the production of potentially dangerous hydrates as the gas temperature is lowered. The lowering of the temperature occurs when the ambient temperature is less than the gas temperature such as in buried and/or submerged pipelines.

In an alternative application of the present invention a heated conduit is arranged to carry gas, the heating effect in this arrangement ensures that the gas temperature is maintained at a level sufficiently high to prevent hydrate formation.

Although the application in this arrangement is different to the arrangement where the conduit carries oil or a solid in suspension, it is apparent that the embodiment used is a variation within the scope of the present invention.

It will be appreciated that the above are only two embodiments of the invention and variation may be made without departing from the scope of the invention.

Claims

1. A heating system for a conduit comprising an electrical conductor arranged in or proximal to the conduit such that in use an electric current flowing in the conductor causes inductive heating of the conduit.

2. A heating system according to claim 1 wherein the conduit is formed from a material which experiences dipolar excitation in a magnetic field of an electric current.

3. A heating system according to claim 2 wherein the magnetic field is produced by an alternating electric current.

4. A heating system according to any preceding claim wherein insulating cable transmitting electricity at high voltage is contained in the conduit.

5. A heating system according to any of claims 1 to 3 wherein the electrical conductor transmits electricity at high voltage is fixed to an outside surface of the conduit.

6. A heating system according to claims 4 or 5 wherein the conduit is a pipe and is buried or submerged.

7. A heating system comprising a conduit having an electrical conductor formed integrally within the body of the conduit such that an electric current flowing in the conductor causes inductive heating of the body of the conduit.

8. A heating system according to any preceding claim wherein a sensor is provided to monitor a change and feedback a signal, which signal is then used to vary the electrical current.

9. A heating system according to claim 8 wherein the sensor monitors the temperature of the conduit.

10. A heating system according to any preceding claim wherein oil is pumped through the conduit.

11. A heating system according to any of claims 1 to 9 wherein gas is pumped through the conduit.

12. A heating system according to any preceding claim wherein a thermal insulating material surrounds the conduit.

13. A heating system substantially as herein described with reference to figures 1 and 2.

14. A heating system substantially as described with reference to figures 3 and 4.