Turbomachinery with switched reluctance motor

Abstract

a casing (12) having a fluid inlet (122) and a fluid outlet (124); one or more stages (14) arranged sequentially within the casing (12); and a flow path (16) extending from the fluid inlet (122) through the one or more stages (14) to the fluid outlet (124), each of the one or more stages including an impeller (142) and an electric motor, the impeller (142) being at least partially located within the flow path (16), the electric motor including a rotor (144) and a stator (146), the rotor (144) being coupled to the impeller (142) and configured to rotate the impeller (142), and the stator (146) being fixedly disposed relative to the casing (12), wherein the turbomachine is characterized in that the stator (146) includes a plurality of electromagnets and the rotor (144) is made of a magnetically permeable metal.

Description

[Technical Field]

[0001] The present disclosure relates to turbomachines with electric motors. More specifically, the subject matter disclosed herein refers to pumps or compressors that are particularly suited for pumping fluids, such as water or other compressible fluids. [Background technology]

[0002] Turbomachinery with electric motors is often used in many industrial sectors such as oil refineries, oil production platforms, subsea systems, offshore installations, etc. Turbomachinery can include electric submersible pumps (ESPs), subsea electric motors, etc.

[0003] A turbomachine may include one or more stages, each of which applies kinetic energy to compress and / or transport a fluid through a flow path by an impeller, the rotation of which is driven by an electric motor coupled to the impeller and disposed within the turbomachine.

[0004] Currently, turbomachines can be equipped with permanent magnet synchronous motors (PMSM).

[0005] For example, U.S. Patent No. 10,294,949 discloses a multi-stage turbomachine including a casing having a fluid inlet and a fluid outlet, and a plurality of stages arranged sequentially within the casing. A flow path extends through the stages from the fluid inlet to the fluid outlet. Each stage includes a rotating impeller and an electric motor embedded in the casing and configured to rotate the impeller at a controlled rotational speed. Each electric motor includes a motor rotor disposed on the impeller and rotating integrally with the impeller, and a motor stator fixedly disposed within the casing.

[0006] Documents US Pat. No. 8,430,653, WO 2019 / 199318, US Pat. No. 1,098,726 and US Pat. No. 6,616,421 are representative of the available prior art.

[0007] However, currently available turbomachines with PMSM motors require permanent magnets in the rotor, which results in bulky structures, and the permanent magnets are traditionally made from heavy and expensive rare earth alloys.

[0008] It may be beneficial to improve the turbomachinery. Summary of the Invention

[0009] Certain aspects commensurate in scope with the originally claimed disclosure are summarized below. These aspects are not intended to limit the scope of the claimed disclosure; rather, these aspects are intended only to provide a brief summary of possible forms of the disclosure. Indeed, the full disclosure may include a variety of forms that may be similar to or different from the aspects set forth below.

[0010] In one aspect, the subject matter disclosed herein relates to a turbomachine comprising: a casing including a fluid inlet and a fluid outlet; one or more stages sequentially arranged within the casing; and a flowpath extending from the fluid inlet through the one or more stages to the fluid outlet, each of the one or more stages including an impeller and an electric motor. The impeller is located at least partially within the flowpath, and the electric motor includes a rotor and a stator, the rotor is coupled to the impeller and configured to rotate the impeller, and the stator is fixedly positioned relative to the casing. In particular, the stator includes a plurality of electromagnets, and the rotor is made of a magnetically permeable metal.

[0011] In another aspect, the subject matter disclosed herein relates to a turbomachinery installation including the turbomachine defined above. [Brief explanation of the drawings]

[0012] A more complete understanding of the disclosed embodiments of this invention and many of the attendant advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings. [Figure 1] 1 is an axial cross-section in the XZ plane of a turbomachine with an electric motor according to the prior art, the turbomachine comprising a number of successively arranged stages. [Figure 2] 2 shows a perspective view of the turbomachine shown in FIG. 1, illustrating a detailed view of a single stage of the turbomachine. [Figure 3] 3 is an extract of FIG. 2 showing an enlarged view of a detail of a turbomachine stage. [Figure 4] FIG. 4 is a perspective view showing details of the PMSM motor of the turbomachine shown in FIGS. 1 to 3. [Figure 5] 1 shows a perspective view of an axial section in the XZ plane of a turbomachine with an electric motor according to a first embodiment of the present disclosure, showing a detailed view of a single stage of the turbomachine; [Figure 6] 5 showing an enlarged view of a detail of a stage of a turbomachine according to a first embodiment of the present disclosure. [Figure 7] FIG. 7 is a perspective view of details of a switched reluctance motor (SRM) motor of the turbomachine shown in FIGS. 5 and 6. [Figure 8] 1 shows a perspective view of an axial section in the XZ plane of a turbomachine with an electric motor according to a second embodiment of the present disclosure, showing a detailed view of a stage of the turbomachine; [Figure 9] 9 shows an axial cross-sectional view in the XZ plane of a detail of a stage of the turbomachine shown in FIG. 8 according to a second embodiment of the present disclosure. [Figure 10] 10 is an excerpt from FIG. 9 showing an enlarged view of a detail of a turbomachine stage according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the field of turbomachinery installations, such as oil refineries, oil production platforms, subsea systems, offshore installations, etc., the turbomachinery may be equipped with one or more PMSM motors.

[0014] Reference is now made to the drawings, and in particular to FIG. 1, which shows an axial cross section in the XZ plane of a turbomachine 1 having a PMSM motor according to the available prior art.

[0015] 1 may be, for example, a wet gas compressor or pump, or more generally, a turbomachine 1 suitable for boosting the pressure of a fluid and / or generating a flow from a fluid inlet 122 to a fluid outlet 124. The liquid may be a compressible liquid, such as a liquid containing a proportion of a gaseous medium.

[0016] The turbomachine 1 comprises a casing 12 including a fluid inlet 122 and a fluid outlet 124, and one or more stages 14 arranged sequentially within the casing 12. The fluid inlet 122 is in fluid communication with the fluid outlet 124 via a flow path 16 that extends from the fluid inlet 122 through the one or more stages 14 of the turbomachine 1 to the fluid outlet 124.

[0017] As shown in Figure 1, the turbomachine 1 includes multiple axial stages 14 arranged in sequence between a fluid inlet 122 and a fluid outlet 16. In the partial view of Figure 1, only two axial stages 14 are shown. Each stage is separated from the next by a stationary diaphragm 18, which is a stationary portion of the turbomachine 1 configured to house an inner case therein. Each stage includes a rotatable impeller 142 that can be driven in rotation by a respective embedded motor.

[0018] Figure 2 shows a perspective view of the turbomachine 1 shown in Figure 1 and shows a detailed view of a single stage 14 of the turbomachine 1. The stage 14 comprises an impeller 142 and an electric motor. Figure 3 shows an extract from Figure 2 showing an enlarged view of a single stage of the turbomachine.

[0019] 2 and 3, the impeller 142 is at least partially positioned within the flow passage 16 to engage the fluid and increase the pressure of the fluid and / or generate a fluid flow. The impeller 142 includes respective impeller blades that may include a root portion, an airfoil portion, and a tip portion. The blades may be annularly arranged blades that form a monolithic ring coupled with the rotor 144.

[0020] 4 shows a perspective view of the electric motor of the turbomachine 1. In particular, the electric motor is a PMSM motor and comprises a rotor 144 and a stator 146.

[0021] The stator 146 is a concentric cylinder that surrounds the rotor 144 and is fixedly disposed relative to the casing 12. The stator 146 includes a plurality of electromagnets formed by respective ferromagnetic cores or yokes and electric coils wound around the respective cores or yokes. The cores or yokes are arranged in an annular shape and extend toward the motor rotor 144. The cores or yokes may comprise laminated sheets of a ferromagnetic metal.

[0022] The rotors 144 are coupled to the impellers 142 and arranged to rotate relative to the stators 146. The rotors 144 are therefore configured to rotate integrally with the respective impellers 146, e.g., at a controlled rotational speed.

[0023] 3 and 4, rotor 144 includes a plurality of electromagnets formed by respective ferromagnetic cores or yokes and electrical coils wound around the respective cores or yokes, the cores or yokes being made from a rare earth material and the electrical coils being made from copper.

[0024] Thus, the turbomachines described with reference to Figures 1-4 include PMSM motors that require permanent magnets in the rotor 144, and as a result, these types of turbomachines have bulky structures and may require a variable frequency drive (VFD) controller, such as a high voltage insulated gate bipolar transistor (HV-IGBT) module, to carefully control the starting torque and reduce inrush current, which is the amount of current drawn by the motor during starting.

[0025] For example, when a PMSM motor is started and the motor speed is near zero, the generated electromagnetic force is low and the inrush current can be high. The high inrush current can cause damage to the motor or other electrical components, and the sudden high torque generation caused by the severe rotor acceleration can also damage the mechanical load.

[0026] Additionally, PMSM motor designs can suffer from windage losses because the presence of permanent magnets in the rotor 144 results in a rotor-stator system design with a wide gap between the rotor 144 and the stator 146. Windage losses refer to losses incurred by the rotor-stator system due to the resistance of the fluid flowing through the gap to the rotation of the rotor 144.

[0027] Furthermore, in PMSM motors, the permanent magnets of the rotor 144 are traditionally made from alloys of rare earth elements, which are heavy and expensive. Therefore, turbomachines with PMSM motors are also heavy and expensive.

[0028] Using SRM motors instead of PMSM motors improves the overall efficiency of turbomachinery, reduces windage losses, reduces problems with excessive inrush currents, and improves performance over a wider range of operating temperatures. SRM motors also allow for simpler, more compact, and less expensive designs.

[0029] The present subject matter therefore relates to a turbomachine 1 comprising one or more SRM motors.

[0030] Reference is now made to Figure 5, which shows a perspective view of an axial cross section in the XZ plane of a portion of a turbomachine 1, according to a first embodiment of the present disclosure. The turbomachine 1 may be part of a known type of turbomachinery installation, such as an oil refinery, an oil production platform, a subsea system, an offshore installation, or the like.

[0031] In the embodiment shown in FIG. 5, the turbomachine 1 comprises a casing 12 including a fluid inlet 122 and a fluid outlet 124 , and one or more stages 14 arranged sequentially within the casing 12 .

[0032] 1 , the fluid inlet 122 is in fluid communication with the fluid outlet 124 through the flow path 16 that extends from the fluid inlet 122 through one or more stages 14 to the fluid outlet 124. Thus, the fluid flows in a generally axial direction through the turbomachine 1 from the inlet 122 toward the outlet 124 and across the one or more stages 14 of the turbomachine 1.

[0033] The turbomachine 1 may include multiple axial stages 14 arranged in sequence between the fluid inlet 122 and the fluid outlet 16. Although only a single axial stage 14 is shown in the partial view of Figure 5, one skilled in the art will understand that a different number of stages 14 may be provided. Each stage is separated from the next by a static diaphragm 18, which is a static portion of the turbomachine 1 that houses the inner case and is configured to separate the different stages 14.

[0034] Each stage applies kinetic energy to compress or transport fluid through the flow path 16 by a rotatable impeller 142. Each stage includes a rotatable impeller 142 that can be driven in rotation by a respective motor. For example, the stages 14 may be organized in pairs such that each impeller 142 configured to rotate in one direction is always followed by the next impeller 142 configured to rotate in the opposite direction.

[0035] In the context of this specification, it is understood that the stages 14 may alternatively be arranged radially, i.e., one radially inside the other, or in a mixed configuration relative to the direction of the flowpath 16. For example, if the flowpath 16 is radial, e.g., centrifugal, the electric motor of each centrifugal stage is arranged axially, in the sense that the motor stator 146 and the motor rotor 144 are aligned along the axis of rotation of the turbomachine 1.

[0036] A more detailed view of a single stage 14 of turbomachine 1 is shown in Figure 6. Stage 14 includes an impeller 142 and an electric motor coupled to the impeller. An enlarged view of a portion of the SRM motor of turbomachine 1 is shown in Figure 7.

[0037] As shown in FIG. 6 , the impeller 142 is at least partially positioned within the flow path 16 to engage the fluid to increase the pressure of the fluid and / or generate a fluid flow. In use, the impeller can act like a flywheel to minimize torque ripple. The impeller includes individual impeller blades that can include a root portion, an airfoil portion, and a tip portion. The blades are arranged in an annular fashion to form a monolithic ring coupled with the rotor 144.

[0038] The impeller 142 may be constructed integrally with the rotor 144 or may be constructed separately and attached to the rotor 144. For example, the impeller 142 may be made of the same material as the rotor 144 or a different material.

[0039] The SRM motor comprises a stator 146 and a rotor 144. The stator 146 comprises a plurality of electromagnets, while the rotor 144 is integrally made of a magnetically permeable metal. Thus, the rotor 144 does not require a plurality of electromagnets, but rather comprises only a magnetically permeable metal fixed to a radial bearing on which the rotor rotates.

[0040] 5 to 7, the stator 146 and the rotor 144 are disposed radially relative to the rotation axis R of the electric motor. The stator 146 is configured to surround the rotor 144 and is disposed fixedly relative to the casing 12.

[0041] The stator 146 includes a plurality of electromagnets formed by respective ferromagnetic cores or yokes and electrical coils wound around the respective cores or yokes. The cores or yokes are arranged in an annular shape and extend toward the motor rotor 144. The cores or yokes may comprise laminated sheets of a ferromagnetic metal. The electrical coils may be made from copper. In one embodiment, the copper windings can be replaced with lighter aluminum windings to achieve a lighter construction.

[0042] The rotor 144 is arranged to rotate relative to the stator 146. The stator 146 and the rotor 144 are arranged to form a gap between them. The gap may be in fluid communication with the flow path 16. The electric motor may include a radial bearing, in which case the rotor 144 is fixed to a radial bearing about which the rotor rotates. The radial bearing may be disposed within the gap. The rotor 144 is coupled to the impeller 142 and configured to rotate integrally with each impeller 146 at a controlled rotational speed, which may be varied, for example, between 0 and 100,000 RPM, for example, by a controller.

[0043] Compared to a PMSM motor, an SRM has a compact structure because the gap between the rotor 144 and the stator 146 can be made smaller, and therefore windage losses caused by the movement of fluid in the gap can be reduced.

[0044] In use, the electrical coils in the stator 146 can be powered to generate a magnetic flux that attracts the rotor 144, generating torque. Because SRM motors are less susceptible to inrush currents, the electrical coils can be powered without the need for a VFD, thereby optimizing efficiency over a range of speeds.

[0045] The turbomachine 1 may include a controller configured to individually control each electric motor of one or more stages 14 as a function of at least one parameter selected from the group consisting of rotational speed, torque, power, or a combination thereof.

[0046] The controller may include one or more processors. The controller may also include a memory and a communication module, which may be communicatively coupled to a server and / or a mobile terminal, such as a tablet, cell phone, or laptop. The communication module may be configured to communicate with the mobile terminal and / or a server, such as a cloud server, using wired or wireless technology to control the rotation of the motor and / or to exchange data related to the operation of the turbomachine 1. For example, wireless technology may include WiFi, cellular technology, near field communication (NFC), Bluetooth, personal area network (PAN), etc. Wired technology may include proprietary cables, RJ45 cables, coaxial cables, fiber optic cables, etc.

[0047] In use, the turbomachine 1 may be controlled by an operator remotely, for example via a mobile terminal, or may be controlled automatically based on programmed instructions stored in the memory of a controller or server.

[0048] Reference is now made to FIG. 8, which shows a perspective view of an axial cross section in the XZ plane of a portion of a turbomachine 1 according to a second embodiment of the present disclosure.

[0049] The turbomachine 1 shown in FIGS. 8 to 10 differs from the turbomachine 1 of the first embodiment in that the stator 146 and the rotor 144 are arranged axially relative to the rotation axis R of the electric motor.

[0050] 8, the stator 146 is arranged opposite the rotor 144 in the direction of the rotation axis R, so as to form a sandwich structure with the rotor 144. In this way, the stator 146 is no longer arranged at least partially within the outer casing 3. In particular, the motor can be arranged within the static diaphragm 18. The thickness of the outer casing 3 can therefore be further reduced, achieving a more compact structure of the turbomachine 1 as well as a saving in the material required for the casing 3.

[0051] 9 and 10, the stator 146 comprises a plate, and a plurality of electromagnets are disposed on the surface of the plate, for example, along the circumferential direction of the plate. The plurality of electromagnets may be formed by respective ferromagnetic cores or yokes and electrical coils wound around the respective cores or yokes. The cores or yokes may comprise laminated sheets of ferromagnetic metal extending toward the motor rotor 146, so as to induce electromagnetic flux in the rotor 144 when powered. The electrical coils may be made of copper or aluminum.

[0052] The stator 146 and the rotor 144 are arranged to form a gap between them. The rotor 144 is arranged to rotate relative to the stator 146. The electric motor may include an axial bearing whereby the rotor 144 is fixed on an axial bearing about which the rotor rotates. The axial bearing may be disposed within the gap.

[0053] 9 and 10 , the gap between the stator 146 and the rotor 144 is isolated from the flow path 16. In particular, the impeller 142 includes a flap-like portion 1422 that extends over the stationary diaphragm 18. The flap-like portion 1422 of the impeller 142 is configured to be fluid-tight, thereby isolating the gap between the stator 146 and the rotor 144 from the flow path 16. For example, the flap-like portion 1422 may include one or more seal rings (not shown) that prevent the working fluid from entering the gap. This configuration minimizes windage losses caused by the working fluid entering the gap due to the serpentine path formed by the blades of the impeller 142 during operation.

[0054] The advantage of the technical solution of this embodiment is that it provides a turbomachine 1 with at least one SRM motor. SRMs are more robust, compact, and fault-tolerant than PMSMs because they do not require rare earth elements in their magnets and therefore overcome the limitations of PMSM motors. In particular, the gap between the rotor and stator can be reduced, resulting in less windage loss.

[0055] Another advantage of the technical solution of the present invention is that the absence of rotor windings and permanent magnets makes it possible to achieve a simpler yet lower cost structure of the turbomachine with less hysteresis losses. Furthermore, the absence of permanent magnets maintains performance over a wider range of operating temperatures of the turbomachine.

[0056] Another advantage of the technical solution of the present invention is that the switched reluctance motor has a higher starting torque without the problem of excessive inrush current, reducing the machine starting problem and improving its general operation.

[0057] While aspects of the present invention have been described in terms of various specific embodiments, it will be apparent to those skilled in the art that many modifications, changes, and omissions are possible without departing from the spirit and scope of the claims. Additionally, unless otherwise specified herein, the order or sequence of any process or method steps may be varied or rearranged according to alternative embodiments.

[0058] Reference will now be made in detail to the embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not as a limitation of the disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. References throughout this specification to "one embodiment" or "an embodiment" or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the disclosed subject matter. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0059] When presenting elements of various embodiments, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Claims

1. a casing (12) having a fluid inlet (122) and a fluid outlet (124); one or more stages (14) arranged sequentially within the casing (12); a flow path (16) extending from the fluid inlet (122) through the one or more stages (14) to the fluid outlet (124); 1. A turbomachine (1), wherein each stage of the one or more stages comprises an impeller (142) and an electric motor, the impeller (142) being at least partially located within the flowpath (16), the electric motor comprising a rotor (144) and a stator (146), the rotor (144) being coupled to the impeller (142) and configured to rotate the impeller (142), and the stator (146) being fixedly disposed relative to the casing (12), A turbomachine, characterized in that the stator (146) comprises a plurality of electromagnets and the rotor (144) is made of a magnetically permeable metal.

2. 2. The turbomachine of claim 1, wherein the stator and the rotor are radially disposed relative to an axis of rotation of the electric motor such that the stator is configured to surround the rotor.

3. The turbomachine of claim 2, wherein the stator (146) and the rotor (144) are positioned to define a gap therebetween, the gap being in fluid communication with the flowpath (16).

4. A turbomachine according to claim 2 or 3, wherein the electric motor comprises radial bearings, the rotor (144) being fixed to the radial bearings about which the rotor rotates.

5. 2. The turbomachine of claim 1, wherein the stator and the rotor are axially disposed relative to a rotational axis of the electric motor, the stator being disposed opposite the rotor in the direction of the rotational axis and forming a sandwich structure with the rotor.

6. The turbomachine of claim 5, wherein the stator (146) and the rotor (144) are arranged to define a gap therebetween, the gap being isolated from the flowpath (16).

7. 7. The turbomachine of claim 6, wherein the impeller comprises a flap-like portion extending over a stationary diaphragm of the turbomachine, the flap-like portion of the impeller configured to be fluid-tight to isolate the gap between the stator and the rotor from the flowpath.

8. The turbomachine of claim 6 , wherein the flap-like portion (1422) comprises one or more seal rings.

9. The turbomachine of any one of claims 5 to 8, wherein the stator (146) comprises a plate, and the plurality of electromagnets are arranged on the plate along a circumferential direction of the plate.

10. A turbomachine according to any one of claims 5 to 9, wherein the electric motor comprises an axial bearing, the rotor (144) being fixed to the axial bearing about which the rotor rotates.

11. 11. The turbomachine (1) according to any one of claims 1 to 10, comprising a controller configured to individually control each electric motor of one or more stages (14) as a function of at least one parameter selected from the group consisting of rotational speed, torque, power, or a combination thereof.

12. The turbomachine (1) according to any one of claims 1 to 11, wherein each of the plurality of electromagnets comprises a magnetically permeable core and a plurality of electrical windings wound around the magnetically permeable core.

13. The turbomachine (1) according to any one of the preceding claims, wherein the impeller (142) is constructed integrally with the rotor (144).

14. The turbomachine (1) according to any one of the preceding claims, wherein the impeller (142) is made of the same material as the rotor (144).

15. A turbomachine installation comprising a turbomachine (1) according to any one of claims 1 to 14.

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