EP3005831B1 - Inductor for induction heating - Google Patents

Description

The invention relates to an inductor for inductive heating of oil sands, oil shale or heavy oil deposits.

In the extraction of heavy oils or bitumen from oil sands or oil shale deposits by means of pipe systems, it is necessary to achieve the greatest possible flowability of the oils to be pumped. Here, the pipe systems are introduced through holes provided for this purpose. For example, an increase in the flow rate can be achieved by an increase in the temperature of the deposits (reservoirs in the soil). According to the prior art, this inductive heaters, so-called inductors are used. In particular, in the case of steam-assisted gravity drainage (SAGD method, narrow steam-assisted gravity drainage), inductive heating is used exclusively or supportively to increase the temperature.

In order to achieve sufficient for the required temperature increase heating power in the vicinity of an inductor are typically large currents of a few hundred amperes necessary because the surrounding the inductor reservoir is usually only slightly electrically conductive. In addition, the inductor is subjected to an alternating current whose frequency is typically in the range of 10 kHz to 200 kHz. However, this results in a high inductive voltage drop along an elongated inductor whose length can usually be more than 1 km. In most cases, therefore, the inductive voltage drop is on the order of a few 100 kV. Such voltage can only be easily handled practically, so that it is necessary to compensate for them.

Such compensation can for example be done by series-connected capacitors as in the patent DE: 10 2007 040 605.5 described. Here are the current-carrying Broken conductor of the inductor and thus have interruption points.

A disadvantage of such a series circuit of capacitors is that the interruption point form weak points of the inductor. Partial discharges can occur at the points of interruption, which can lead to the destruction of the inductor.

document WO 2009/109489 A1 discloses an inductor for inductive heating of oil sands and heavy oil deposits by means of live conductors.

The present invention is therefore an object of the invention to provide an improved over the prior art inductor.

The object is achieved by an inductor having the features of the independent claim. In the dependent claims advantageous refinements and developments of the invention are given.

The inductor according to the invention for the inductive heating of oil sand, oil shale or heavy oil deposits by means of current-carrying conductors comprises at least two areas and a first type connection of the two areas, the two areas each having at least a first and a second multifilament conductor. According to the invention, the connection of the first type is configured such that the first multifilament conductor of the first region is electrically coupled via a first capacitor to the second multifilament conductor of the first region, the first multifilament conductors of the first and second regions are electrically conductively connected, and the second multifilament conductor of second region is electrically coupled via a second capacitor to the first multifilament conductor of the first region.

As a result, according to the invention, a partial discharge at break points of the inductor is avoided. Here, the interruption point of the inductor corresponds to the interruption of the second multifilament conductor by the first capacitor.

The avoidance of partial discharges succeeds by connecting the multifilament conductors via a first and second capacitor in the manner provided by claim 1. In particular, conductors of the respective multifilament conductors are linked according to the invention via a common first and / or second capacitor. It should be noted that the conductors of a multifilament conductor are always understood to mean either all conductors of the multifilament conductor or at least a part of the conductors of the multifilament conductor is to be understood.

It is advantageous that the first and second capacitors are connected in parallel with the capacitances of the conductors (line capacitances) of a region, so that there is a parallel connection. This increases the total capacity of the respective area, since the capacitances of capacitors connected in parallel add up.

The inductor according to the invention thus advantageously combines distributed capacitors with concentrated capacitors. Distributed capacitors are to be understood as the line capacitances. Concentrated capacitors are to be understood as meaning the first and second capacitors. It is thus proposed according to the invention a combination of concentrated and distributed capacitors, which allows a capacitive compensation of the inductor without partial discharges.

• Der zweite Multifilamentleiter des ersten Bereiches des Induktors wird wenigstens einmal unterbrochen. An der Unterbrechungstelle werden die Leiter des zweiten Multifilamentleiters des ersten Bereiches über einen konzentrierten ersten Kondensator mit den Leitern des nicht unterbrochenen ersten Multifilamentleiter elektrisch verkoppelt. Über einen konzentrierten zweiten Kondensator ist vorgesehen den zweiten Multifilamentleiter des zweiten Bereiches mit dem nicht unterbrochenen ersten Multifilamentleiter des ersten Bereiches elektrisch kapazitiv zu verschalten. Der erste Multifilamentleiter des ersten Bereiches ist mit dem ersten Multifilamentleiter des zweiten Bereiches verbunden und wird somit bei einer Verbindung erster Art nicht unterbrochen. Insbesondere sind die Leiter des ersten und zweiten Multifilamentleiters vor und nach der Verbindung über den ersten und/oder zweiten Kondensators zu jeweils einem Leiter zusammengeführt.

In other words, the invention can be described as follows:

• The second multifilament conductor of the first region of the inductor is interrupted at least once. At the point of interruption, the conductors of the second multifilament conductor of the first region are electrically coupled via a concentrated first capacitor to the conductors of the uninterrupted first multifilament conductor. About a concentrated second capacitor is provided the second Multifilament conductor of the second region with the uninterrupted first multifilament conductor of the first region electrically capacitively interconnect. The first multifilament conductor of the first region is connected to the first multifilament conductor of the second region and thus is not interrupted in a connection of the first type. In particular, the conductors of the first and second multifilament conductors are combined before and after the connection via the first and / or second capacitor to a respective conductor.

According to an advantageous embodiment of the invention, the inductor comprises a further third region which is electrically connected to the second region via a connection of the second type, wherein the connection of the second type is configured such that the first multifilament conductor of the second region via a further first capacitor the second multifilament conductor of the second region is electrically coupled, the second multifilament conductor of the second and third regions are electrically conductively connected, and the first multifilament conductor of the third region is electrically coupled via a further second capacitor to the second multifilament conductor of the second region.

Advantageously, a connection of the second type corresponds to a connection of the first type in which the first and second multifilament conductors are interchanged. This creates symmetry between the first and second multifilament conductors. As a result, the inductive voltage drop of the first and the second multifilament conductor is compensated.

According to a further advantageous embodiment, the inductor comprises more than three areas, wherein alternately two areas are each connected to a connection of the first and second type.

Advantageously, this allows an inductor with several areas. It is particularly advantageous that by the connection of the first and second type partial discharges to interruptions The multifilament conductor can be avoided and thus destruction of the inductor can be prevented by partial discharges even in a plurality of areas.

In an advantageous development of the invention, the first and second multifilament conductors each comprise at least two conductors, wherein the conductors form the filaments of the multifilament conductor.

Advantageously, a conductor of the first multifilament conductor is always capacitively coupled to a conductor of the second multifilament conductor. As a result, line capacities and thus distributed capacities are formed.

In a further advantageous development, the first and second multifilament conductors comprise a plurality of at least 1000 and at most 5000 conductors, wherein the conductors form the filaments of the multifilament conductor.

As a result, the heating power of the inductor is advantageously increased significantly.

According to an advantageous embodiment of the invention, the individual conductors of the multifilament conductors extend substantially parallel along a longitudinal axis of the inductor.

This advantageously increases the line capacity.

According to a further advantageous embodiment, the individual conductors of the multifilament conductors form an interlaced structure which extends along a longitudinal axis of the inductor.

This advantageously allows a cable arrangement of the multifilament conductors, which is stabilized by the interweaving on the one hand and on the other to the formation of concentrated capacitances (line capacities) is suitable.

In an advantageous development of the invention, the at least two multifilament conductors are capacitively coupled at least in the first and in the second region, so that a third capacitor is formed in the respective region.

In this case, the third capacitor advantageously corresponds to the line capacitances of the regions.

In a further advantageous development, a total capacity of the first and second capacitors is less than a total capacity of the third capacitors.

Particularly advantageous is a total capacity of the first and second capacitors, which contributes less than 5% to the total capacitance of the third capacitors.

According to an advantageous embodiment of the invention, the first and / or second capacitor each comprise two electrodes, wherein the electrodes are formed by merging individual conductors of a multifilament conductor.

This advantageously helps to avoid partial discharges at the points of interruption. The first and / or second capacitor is therefore formed by merging the conductors of the multifilament conductor coupled by the first and / or second capacitor.

According to a further advantageous embodiment, the electrodes are hemispherical in shape.

This advantageously helps to avoid partial discharges at the points of interruption.

In an advantageous development of the invention, a gap, which is arranged between the two electrodes of the first capacitor and / or of the second capacitor, comprises a ceramic or mineral insulating material.

As a result, the avoidance of partial discharges at the points of interruption is particularly advantageously supported.

In a further advantageous development, the insulating material comprises at least one material from the mica group.

Materials of the mica group have a high dielectric strength, so that advantageously the avoidance of partial discharges at the points of interruption is additionally supported.

The invention will now be described by way of a preferred embodiment with reference to the appended drawing, in which the single figure shows a schematic representation of an inductor according to the invention.

Similar elements are provided in the figure with the same reference numerals.

The single figure shows schematically an inductor 1, which along a longitudinal axis 40 at least four regions 20, 22, 24, 26 has. In this case, with respect to the longitudinal axis 40 adjacent regions 20, 22, 24, 26 are alternately connected to a first type connection 28 and a second type connection 30. Each of the regions 20, 22, 24, 26 has two multifilament conductors 2, 4, wherein the multifilament conductors 2, 4 each comprise six conductors 2a ... f, 4a ... f. In each area, the conductors 2a... F of the first multifilament conductor 2 are capacitively coupled to the conductors 4a... F of the second multifilament conductor 4. Such a capacitive coupling is made possible by the parallel arrangement of the conductors 2a... F, 4a... F along the longitudinal axis 40 of the inductor 1.

The first type connection 28 has first and second capacitors 6, 8. Before the connection via the first and / or the second capacitor 6, 8, the multifilament conductors are brought together to form a conductor. Here, the first capacitor 6 couples the first and second Multifilament conductor 2, 4 of the first region 20. The second capacitor 8 couples the first multifilament conductor 2 of the first region 20 with the merged second multifilament conductor 4 of the second region 22. The first multifilament conductor 2 of the first region 20 is brought together and merged with the first multifilament conductor second of the second region 22 is electrically coupled.

The second area 22 is adjoined by a third area 24. In this case, the second area 22 is now connected to the third area 24 via a connection of the second type 30. The merged and interrupted first multifilament conductor 2 of the second region 22 is coupled via a first capacitor 6 to the merged second multifilament conductor 4 of the second region 22. The merged second multifilament conductor 4 of the second region 22 is simply electrically connected to the merged second multifilament conductor 4 of the third region 24. In addition, the in turn merged multifilament conductor 2 of the third region 24 is capacitively coupled to the second multifilament conductor 4 of the second region 22 via a second capacitor 8.

The named and recognizable scheme now continues along the longitudinal axis 40 of the inductor 1. This results in the third region 24, a fourth region 26 which is connected to a connection of the first type 28 with the third region 24. In general, this scheme can be applied to any number of areas 20, 22, 24, 26 of the inductor 1 application.

In the regions 20, 22, 24, 26, the capacitively coupled conductors 2a... F, 4a... F form distributed capacitors. In the first and second type connections 28, 30, on the other hand, concentrated capacitors 6, 8 are formed by the first and second capacitors 6, 8. As a result, distributed capacitors with concentrated capacitors 6, 8 are advantageously combined along the inductor 1, so that partial discharges are avoided at break points and thus providing an improved inductor over the prior art.

Claims (13)

1. Inductor (1) for the inductive heating of deposits of oil sand, oil shale or extra-heavy oil using current-carrying conductors (2a...f, 4a...f) comprising

   - at least two areas (20, 22) which each have at least one first and one second multifilament conductor (2, 4), characterised by a connection of the first type (28) of the two areas (20, 22), wherein the connection of the first type (28) is embodied such that

   - the first multifilament conductor (2) of the first area (20) is electrically coupled to the second multifilament conductor (4) of the first area (20) by way of a first capacitor (6),

   - the first multifilament conductor (2) of the first and second area (20, 22) are connected in an electrically conducting manner,

   - and the second multifilament conductor (4) of the second area (22) is electrically coupled to the first multifilament conductor (2) of the first area (20) by way of a second capacitor (8).
2. Inductor (1) according to claim 1 having a further third area (24), which is electrically connected to the second area (22) by way of a connection of the second type (30), wherein the connection of the second type (30) is embodied such that

   - the first multifilament conductor (2) of the second area (22) is electrically coupled to the second multifilament conductor (4) of the second area (22) by way of a further first capacitor (6),

   - the second multifilament conductor (4) of the second and third area (22, 24) are connected in an electrically conducting manner,

   - and the first multifilament conductor (2) of the third area (24) is electrically coupled to the second multifilament conductor (4) of the second area (22) by way of a further second capacitor (8).
3. Inductor (1) according to claim 2 having more than three areas (20, 22, 24, 26), wherein each two areas are alternately connected in each case to a connection of the first and second type (6, 8).
4. Inductor (1) according to one of the preceding claims, characterised in that the first and second multifilament conductor (2, 4) each comprises at least two conductors (2a...f, 4a...f), wherein the conductors (2a...f, 4a...f) embody the filaments of the multifilament conductor (2, 4).
5. Inductor (1) according to one of the preceding claims, characterised in that the first and second multifilament conductor (2, 4) comprises a plurality of at least 1000 and at most 5000 conductors (2a...f, 4a...f), wherein the conductors (2a...f, 4a...f) embody the filaments of the multifilament conductor (2, 4).
6. Inductor (1) according to claim 4 or 5, characterised in that the individual conductors (2a...f, 4a...f) of the multifilament conductors (2, 4) essentially run in parallel along a longitudinal axis (40) of the inductor (1).
7. Inductor (1) according to one of claims 4 to 6, characterised in that the individual conductors (2a...f, 4a...f) of the multifilament conductors (2, 4) embody an interlaced structure, which extends along a longitudinal axis (40) of the inductor (1).
8. Inductor (1) according to one of the preceding claims, characterised in that the at least two multifilament conductors (2, 4) are capacitively coupled at least in the first and in the second area (20, 22), so that a third capacitor is embodied in the respective area.
9. Inductor (1) according to claim 8, characterised in that a total capacitance of the first and second capacitors (6, 8) is lower than a total capacitance of the third capacitors.
10. Inductor (1) according to one of the preceding claims, characterised in that the first and/or second capacitor (6, 8) each comprises two electrodes, wherein the electrodes are embodied by a merging of individual conductors (2a...f, 4a...f) of a multifilament conductor (2, 4).
11. Inductor (1) according to claim 10, characterised in that the electrodes are hemispherical.
12. Inductor (1) according to claim 10 or 11, characterised in that a space, which is arranged between the two electrodes of the first capacitor and/or of the second capacitor (6, 8) comprises a ceramic or mineralized insulating material.
13. Inductor (1) according to claim 12, characterised in that the insulating material comprises at least one material from the mica group.

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