GB2513286A

GB2513286A - Apparatus

Info

Publication number: GB2513286A
Application number: GB1219229.0A
Authority: GB
Inventors: Yerasimos Angelis
Original assignee: G A R & D Ltd
Current assignee: G A R & D Ltd
Priority date: 2012-10-25
Filing date: 2012-10-25
Publication date: 2014-10-29
Anticipated expiration: 2032-10-25
Also published as: GB2513286B; GB201219229D0

Abstract

A generator comprises a rotor 102 having plural blades 112 extending radially from it and at least one of a pair of magnets and coils; and a stator comprising the other of the pair of magnets and coils. The coils are arranged such that when the rotor rotates with respect to the stator an electromotive force is generated. The rotor can be a tubular body outside and coaxial with the stator with the blades 112 pre-cast on its external face. The rotor can be tapered in cross section with its wider end at a fluid flow inlet end of the generator. Preferably the magnets are permanent magnets on the rotor and coils on the stator are connected to transmit power for recovery. The generator can have a housing outside the rotor and stator; be positioned axially in a pipeline; and used in a geothermal well directly driven by fluid flow. Plural generators can be arranged in series or in parallel.

Description

APPARATUS

This invention relates to an electric generation apparatus which can convert fluid flow into electrical energy.

Many geothermal wells produce steam but suffer from a particular disadvantage of carrying other particulates along with the steam.

The most common method is to use large scale steam turbines which are rotated by the produced flow and so generate mechanical power. In addition, equivalent scale electric generators are connected in line to these turbines in order to convert the produced mechanical power to electricity, which is then supplied to the grid.

However, the steam cannot be used directly on the conventional steam turbines because it will introduce solid particles and other substances to the machinery.

This, in turn, will cause wear of the turbine blades and their associated parts, necessitating the costly replacement of one or both.

For servicing the turbines must still be shut down and serviced periodically, while is very costly to replace the whole unit in order to allow power generation to carry on.

In an attempt to mitigate such shut-downs, the steam process plants become larger and more complicated and costly.

Moreover, the generators and turbines which convert steam for a whole host of different energy sources (e.g. hydro, solar,) are generally expensive.

Furthermore, the inventor of the present invention has noted that the provision of steam purification units, turbines and generators is unsightly.

According to the present invention there is provided a generator comprising: a rotor comprising a plurality of blades extending radially therefrom; the rotor also comprising at least one of (i) a pair of magnets and (ii) coils; a stator comprising the other of (i) the pair of magnets and (ii) the coils; wherein the rotor is rotatably disposed with respect to the stator and wherein the coils are arranged such that when the rotor is moved with respect to the stator that an electromotive force is generated.

The rotor being rotatably disposed means it can rotate with respect to the stator in use. Such rotation normally creates an electrical current because the pair of magnets will interact with the coils and create an electromagnetic field when the rotor is rotating. Thus in use, fluid drives rotation of the rotor by contact with the blades, the interaction of the magnets and the coils creates an electrical current.

Normally the rotor is a tubular body which is outside of, and more normally substantially encloses the stator, although for certain embodiments the stator may be outside of the rotor.

The pair of magnets are normally of opposite polarity.

Thus the inventor of the present invention has gone against the normal procedure in the art which is to separate fluid environments from electric environments.

Embodiments of the present invention are particular suitable for geothermal or solar applications, especially geothermal.

Normally a housing is provided which is outside of, and more normally substantially encloses the rotor and the stator.

The respective longitudinal axes of the rotor and stator are normally parallel to each other and are often the same.

Preferably the rotor comprises the pair of magnets and the stator comprises the coils.

Normally there is more than one pair of magnets. Preferably the magnets are permanent magnets.

This magnets may be embedded on the rotor. Embodiments with the magnets, especially permanent magnets, on the rotor are especially preferred.

Preferably the generator is arranged such that, between the stator and the rotor, there is an annulus which allows the rotor to rotate preferably without mechanical interference. This annulus may be oil filled and retained by mechanical seals, but it can also be seal-less to allow some fluid to pass through.

The stator may be a solid shaft.

The generator is normally positioned axially within a pipeline of fluid.

There may be more than one coils. Preferably the stator is surrounded by the coils, which are normally electrical coils and are arranged in such a configuration so as to act as a stator with magnetic poles.

The stator is preferably connected to a power cable which transmits the electrical power to the grid without the need of brushes or other mean of electrical power contactors. Thus for preferred embodiments, the coils are provided on the stator which allows the easier transfer of electrical power generated since it is a non-rotating component of the generator.

The blades are typically provided on an external face of the rotor.

The blades can have different sizes and angles along its longitudinal axis. When fluid passes through, normally between the housing and the rotor, lateral forces will act on the blades and rotate the rotor.

Typically the blades are provided at an angle intermediate to the longitudinal axis of the generator and, 90 degrees to this axis. There is often more than 10 blades, optionally more than 25, or more than 50. The blades may be pre-cast with the rest of the rotor.

There may be a set of blades spaced apart around the circumference, and many sets longitudinally spaced from each other. For example, there email be more than five sets and each having more than five blades.

Preferably the rotor has a tapered cross section, optionally frusto-conical.

Therefore the cross section extends from a wider end to a narrow end with the wider end at the fluid inlet end of the generator. Preferably therefore the housing is tapered.

It is thought that the centrifugal forces generated by these lateral forces will be equivalent to the power generated by the generator.

The entire stator is preferably potted with selected resin so mechanical seals are not necessary to use for every application.

If the pipeline is vertical to the ground, such as a geothermal well, then the fluid inlet of the generator is preferably disposed at the bottom end, while an outlet is disposed at the top of the generator.

A plurality of generators may be arranged in parallel and/or in series. Each generator is preferably in the range of 50-150ft, normally 80-1 20 feet. For example, each well can have a plurality of generators arranged in series. Then a plurality of such in-series sets may be arranged in parallel at the same area. This approach can apply to mega projects.

The invention also provides an energy extraction system comprising a plurality of generators as described herein arranged in parallel. In use, some or all of the generators can be taken off-line on occasion for repair or maintenance or for other reasons.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which: Fig. 1 is a schematic view of a plurality of generators in accordance with the present invention; Fig. 2 is a cross section of a first embodiment of a generator in accordance with the present invention, comprising a solid shaft stator and a tubular body rotor; Fig. 3a is a side view of a more detailed embodiment of a generator (without a housing) in accordance with the present invention; Fig. 3b is a sectional view of the Fig. 3a generator along the section of A-A; Fig. 3c is an end view of the Fig. 3a generator as viewed from the inlet end; Fig. 3d is an opposite end view of the Fig. 3a generator, as viewed from the outlet end; Fig. 3e is an isometric view of the Fig. 3a generator; Fig. 4a is a side view of an embodiment of a generator with a housing in accordance with the present invention; Fig. 4b is a sectional view of the Fig. 4a generator along the section of A-A; Fig. 4c is an end view of the Fig. 4a generator as viewed from the inlet end; Fig. 4d is an opposite end view of the Fig. 4a generator, as viewed from the outlet end; Fig. 4e is an isometric view of the Fig. 4a generator; Fig. 4f is a sectional view of the fig 4a generator through line B-B; and, Fig. 5 is a perspective view of the stator in accordance with the present invention.

Fig. 1 illustrates a general system where fluid flow, such as steam or water, is generated from a geothermal well, and directed to a number of generators lOa, lOb, lOc, lOd installed in a parallel configuration on the system inlet flow. This parallel arrangement allows service/maintenance routine to take place without shutting down the entire power generation plant, when maintenance is required.

Each generator can be replaced by isolating the related pipeline on it, while allowing the majority of the electrical generators to operate during the standard maintenance routine.

Fig. 2 represents a cross-sectional view of a first embodiment of a generator 10.

The generator 10 comprises a housing 01 which defines a tapered inner bore 10.

Within the bore 10 is a tubular rotor 02 with blades 12 attached on the outer surface area thereof and an assembly of permanent magnets 03 attached to its inner surface. The rotor 02 is supported by bearing/seal 06 at either end.

Additional bearings can be used for certain other embodiments, depending on the particular application scale.

A stator 04 is provided within the rotor 02 and the stator 04 comprises one or more pairs of poles winded with copper coils "windings" (or coils made from other suitable material). The stator 04 is supported on a solid shaft 05 and permanently fixed at the centre of the generator.

The generator 10 is placed in series in a production line of motive fluid, typically water or steam. When fluid passes between the housing 01 and the rotor 02 its contact with the blades 12 causes the rotor 02 to rotate on its longitudinal axis.

Since the magnet assembly 03 is attached as an integral body with the rotor 02 at all times, it rotates along with it the rotor 02.

The interaction of the magnet tubular assembly 03 and the coils on the stator 04 creates an electromagnetic force! measured by the scale of the application. This electromagnetic force is recovered as electric current and fed into the grid or used for other purposes.

When the magnet tubular assembly 03 is at rest it will react with the stator body 04 and maintain a magnetic field, provided by the permanent magnets.

The embodiments shown in Figs. 3 and 4 function using the same principle and use equivalent numbering but starting at 100. A fluid acts on blades 112 and rotates a tubular rotor 102 which generates a current by interaction between permanent magnets (not shown in Figs. 3) and coils 107 on a stator 104.

As can be seen from the figures. a plurality of blades 112 are provided on the external face of the rotor which convert the generally linear flow of fluid into rotational movement of the rotor. The interaction of the magnets and the coils then generates an electric current.

In Figs 4a -4e the generator is shown including a housing 101. A cross section of Fig. 4a is shown in Fig. 4b and illustrates the position of the magnets 103 and the coils 104.

A stator 4 is shown in isolation in Fig. 5.

Preferred embodiments have the inner tubular piece cast as a single piece including the blades 112, rather than have the blades retro-fitted onto the tube.

In this way they can be more robust in use.

Whilst this embodiment illustrates use with geothermal wells, it can also be used with a variety of other energy sources, which generate steam or water flow as part of the energy extraction process e.g. coal, solar, hydro or nuclear power stations which heat water which in turn drive generators.

For certain embodiments, the generator may be placed downhole, in a well, in order to generate power in the well. They may be placed several km deep in certain wells, such as geothermal wells. In alternative uses, they may be used to power a rig. A housing can also be provided with coils Embodiments of the invention benefit in that the coils are static and so retrieving power from the coils is much easier compared to generators where coils are rotating and the current must be recovered from the rotating element through a complicated mechanism.

Embodiments of the invention benefit in that the use of permanent magnets also means an electrical connection to power the magnets is not required for such embodiments.

Embodiments of the invention benefit in that compared to conventional generators they can have less seals and bearings and are more efficient.

Moieovei, the putty of the steam/water which is sent thiough the ceitain embodiments of the generator described herein, can be geothermal well fluid.

Therefore cleaning steps for fluid (e.g. that recovered from geothermal wells) may not require for such embodiments, and an expensive step in the exploitation of energy from geothermal wells may be avoided.

Moreover still, the parallel arrangement of certain embodiments of the invention allows one (geothermal generator unit) turbine to be taken off-line for maintenance or repair without stopping the others. Indeed, maintenance in geneial is easier for certain embodiments of the invention because the parts can easily be removed and replaced.

Another important advantage of ceitain embodiments of the invention is that advanced seals are not required since fluid entering between the stator and rotor is not a critical problem for certain embodiments of the present invention.

Conventional systems use seals to retain lubricant within the motors, generators, and any other down-hole lotaly equipment, and seals are prone to ciitical failure One further advantage of certain embodiments is that the coils and the permanent magnets are arranged relatively close together. This increases the power output from the genelatol.

Thus an advantage of embodiments of the invention is that providing a generator which is directly driven by fluid flow is more surprisingly more efficient than conventional generators.

Moreover! the components of certain embodiments are normally far more robust that steam turbines, and so the purification of the stream from geothermal or other sources, can be reduced or avoided.

Also, an advantage of certain embodiments is that the device of the present invention may be provided downhole, thus not remaining industrial devices on the surface where they may be unsightly.

Improvements and modifications may be made without departing from the scope of the invention.

Claims

Claims 1. A generator, when used in a geothermal well, comprising: a rotor comprising a plurality of blades extending radially therefrom; the rotor also comprising at least one of (i) a pair of magnets and (ii) coils; a stator comprising the other of (i) the pair of magnets and (ii) the co i Is; wherein the rotor is rotatably disposed with respect to the stator; and wherein the coils are arranged such that when the rotor is moved with respect to the stator that an electromotive force is generated.

CYD
2. A generator as claimed in claim 1, wherein the rotor is a tubular body which is outside of the stator.
3. A generator as claimed in either preceding claim, wherein the respective longitudinal axes of the rotor and stator are parallel to each other.LU
4. A generator as claimed in claim 3, wherein the respective longitudinal axes of the rotor and stator are co-axial.
5. A generator as claimed in any preceding claim, wherein the rotor comprises the pair of magnets and the stator comprises the coils.
6. A generator as claimed in any preceding claim, wherein the pair of magnets are permanent magnets.
7. A generator as claimed in any preceding claim, wherein the stator is connected to a power transmission means which transmits the electrical power onwards for recovery or use.Amendments to the claims have been made as follows: Claims 1. A generator, when used in a geothermal well, comprising: a rotor comprising a plurality of blades extending radially therefrom; the rotor also comprising at least one of (i) a pair of magnets and (ii) coils; a stator comprising the other of (i) the pair of magnets and (ii) the co i Is; wherein the rotor is rotatably disposed with respect to the stator; and wherein the coils are arranged such that when the rotor is moved with respect to the stator that an electromotive force is generated.CYD 2. A generator as claimed in claim 1, wherein the rotor is a tubular body which is outside of the stator.3. A generator as claimed in either preceding claim, wherein the respective longitudinal axes of the rotor and stator are parallel to each other.LU4. A generator as claimed in claim 3, wherein the respective longitudinal axes of the rotor and stator are co-axial.5. A generator as claimed in any preceding claim, wherein the rotor comprises the pair of magnets and the stator comprises the coils.6. A generator as claimed in any preceding claim, wherein the pair of magnets are permanent magnets.7. A generator as claimed in any preceding claim, wherein the stator is connected to a power transmission means which transmits the electrical power onwards for recovery or use.
8. A generator as claimed in any preceding claim! wherein the blades are provided on an external face of the rotor.
9. A generator as claimed in any preceding claim, wherein there is more than 10 blades, optionally more than 25, more optionally more than 50.
10. A generator as claimed in any preceding claim, wherein the blades are pre-cast with the rest of the rotor.
11. A generator as claimed in any preceding claim, wherein the rotor has a tapered cross-section.
12. A generator as claimed in claim 11, wherein the cross-section of the rotor extends from a wider end to a narrow end with the wider end at a fluid inlet end of the generator.
13. A generator as claimed in any preceding claim, wherein there is more than one pair of magnets.
14. A generator as claimed in any preceding claim, wherein a housing is provided which is outside of the rotor and the stator.
15. A generator as claimed in any preceding claim, which is positioned axially within a pipeline of fluid.
16. A plurality of generators as claimed in any preceding claim, arranged in series.
17. A plurality of generators as claimed in any preceding claim, arranged in parallel.