Compression system with double stage impeller

Abstract

A compression system comprising a centrifugal dual impeller configured to rotate around a rotating axis, the centrifugal dual impeller comprising a hub, a plurality of first blades having a blade root mechanically coupled to the hub and defining a plurality of first flow paths, a shroud mechanically coupled to a blade tip of the plurality of first blades, and a plurality of second blades having a blade root mechanically coupled to the shroud and defining a plurality of second flow paths. The plurality of first flow paths is configured to compress a first fluid flow and the plurality of second flow paths is configured to compress a second fluid flow, which may be the same fluid of the first fluid flow or a different fluid. The compression system further comprises a stator potion comprising a first volute developing around the rotating axis, the first volute being fluidly coupled to the plurality of first flow paths and configured to receive the first fluid flow discharged by the plurality of first flow paths, and a second volute developing around the rotating axis, the second volute being fluidly coupled to the plurality of second flow paths and configured to receive the second fluid flow discharged by the plurality of second flow paths.

Description

TITLECompression system with double stage impellerDESCRIPTIONTECHNICAL FIELD

[0001] The subject-matter disclosed herein relates to an innovative compression system with a centrifugal dual impeller.BACKGROUND ART

[0002] A centrifugal compressor is a device that compresses a fluid flowing through a rotating impeller by applying a centrifugal force to the fluid. The fluid discharged by the impeller typically goes through a volute in order to increase the efficiency of the compressor system and then is discharged out of the casing of the compressor. To further increase the efficiency of the compression system, the fluid may also pass through a vane or vaneless diffuser located between the impeller outlet and the volute so to convert the fluid kinetic energy to potential energy or static pressure.

[0003] The centrifugal compressor systems of the related art include also a driver which produces a driving force and a rotating shaft which is connected to the impeller and mechanically coupled to the driver. In order to process multiple fluids or to increase further the fluid pressure (i.e. to have multiple compressor stages), the compressor train may also include a central low-speed wheel (known as “bull gear”) and multiple pinion gears on the outside of it driving multiple impeller shafts and hence multiple centrifugal compressors. Such configuration has the major disadvantage to have a non-neglectable footprint.

[0004] For plants in which the installation of a compressor was not initially considered, for example for applications like Carbon Capture and Utilization Storage (=CCUS), it could be difficult to find the needed space to install all the equipment. Therefore, in order to allow the installation of a compressor also in a narrow zone, it would be desirable to have a compressor system with a smaller footprint.SUMMARY

[0005] According to an aspect, the subject-matter disclosed herein relates to a compression system comprising a centrifugal dual impeller configured to rotate around a rotating axis, the centrifugal dual impeller comprising a hub, a plurality of first blades having a blade root mechanically coupled to the hub and defining a plurality of first flow paths, a shroud mechanically coupled to a blade tip of the plurality of first blades, and a plurality of second blades having a blade root mechanically coupled to the shroud and defining a plurality of second flow paths. The plurality of first flow paths is configured to compress a first fluid flow and the plurality of second flow paths is configured to compress a second fluid flow. The compression system further comprises a stator potion comprising: a first volute developing around the rotating axis, the first volute being fluidly coupled to the plurality of first flow paths and configured to receive the first fluid flow discharged by the plurality of first flow paths, and a second volute developing around the rotating axis, the second volute being fluidly coupled to the plurality of second flow paths and configured to receive the second fluid flow discharged by the plurality of second flow paths.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:Fig. 1 shows a longitudinal section of an embodiment of an innovative compression system with a centrifugal dual impeller,Fig. 2 shows an embodiment of a centrifugal dual impeller which can be used in the innovative compression system of Fig. 1, andFig. 3 shows a transversal section of an embodiment of a first and a second volute of the innovative compression system of Fig. 1.DETAILED DESCRIPTION OF EMBODIMENTS

[0007] According to an aspect, the subject-matter disclosed herein relates to an innovative compression system which can exploit the benefit of a dual stage impeller, i.e. an impeller which has implemented two different flow paths on the same hub to compress two different fluid flows (or to compress the same fluid flow in two compressor stages in the same impeller). The compression system of the present solution is provided with a first volute coupled to a first flow path of the compression system and a second volute coupled to a second flow path of the compression system, possibly interpenetrated between each other, so that the efficiency of the two compressor flow paths is increased and different system configurations are possible.

[0008] According to the disclosed solution, with respect to the prior art solutions, the footprint of the compression system may be reduced (having the same compression ratio) or the compression ratio may be increased (having the same footprint).

[0009] Reference now will be made in detail to embodiments of the disclosure, examples of which are illustrated in the drawings. The examples and drawing figures are provided by way of explanation of the disclosure and should not be construed as a limitation of the disclosure. In fact, 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. In the following description, similar reference numerals are used for the illustration of figures of the embodiments to indicate elements performing the same or similar functions. Moreover, for clarity of illustration, some references may be not repeated in all the figures.

[0010] Referring now to the drawings, Fig. 1 is a schematic longitudinal section of an embodiment of an innovative compression system 100 according to the present solution. The compression system 100 comprises a centrifugal dual impeller 10 which is configured to rotate around a rotating axis R. In particular, the centrifugal dual impeller 10 may be mechanically coupled to a rotating shaft, the rotating shaft being configured to transmit motion to the centrifugal dual impeller 10 so to drive the centrifugal dual impeller. Advantageously, the rotating shaft is mechanically coupled to a driver, for example a turbine or a motor, in particular an electric motor.

[0011] According to a possibility, the compression system 100 may be coupled to an integrally geared system. In particular, the rotating shaft may be mechanically coupled to a wheel gear (known as “bull gear”), for example the rotating shaft being a rotating pinion-shaft or being mechanically coupled to a pinion wheel; the wheel gear is in turn mechanically coupled to the driver so that the wheel gear is driven by the driver. According to this possibility, the wheel gear of the integrally geared system may advantageously be coupled to a plurality of compression system 100 and drive a plurality of centrifugal dual impellers 10.

[0012] With reference to Fig. 2, it is shown, for example and without limitation, a centrifugal dual impeller 10 which can be used in the innovative compression system 100 described herein. The centrifugal dual impeller 10 comprises a hub 11, a plurality of first blades 12, a shroud 16 and a plurality of second blades 14. The plurality of first blades 12 have a blade root mechanically coupled to the hub and a blade tip mechanically coupled to the shroud 16, the plurality of first blades 12 defining a plurality of first flow paths 13 configured to compress a first fluid flow. In particular, the inlet of the plurality of first flow path 13 (i.e. the portion which includes the leading edges of the plurality of first blades 12) defines a first annulus configured to receive the first fluid flow to be compressed.

[0013] The plurality of second blades 14 have a blade root mechanically coupled to the shroud 16, the plurality of second blades 14 defining a plurality of second flow paths 15 configured to compress a second fluid flow. In particular, the inlet of the plurality of second flow path 15 (i.e. the portion which includes the leading edges of the plurality of second blades 14) defines a second annulus which is concentric to the first annulus, in particular external to the first annulus, configured to receive the second fluid flow to be compressed.

[0014] As it will be better disclosed in the following, the first fluid flow and the second fluid flow may be the same fluid (i.e. having the same composition) with the same mass flow or with different mass flows, or may be different fluids (i.e. having different compositions).

[0015] It is to be noted that the blade tip of the plurality of second blades 14 may be free (as shown for example in Fig. 2) and the plurality of second flow paths 15 are limited above by a stator portion of the compression system 100, in order to limit the stresses on the impeller, or, alternatively, the blade tip of the plurality of second blades 14 may be mechanically coupled to a secondshroud (not shown in any figure).

[0016] With non-limiting reference to Fig. 1, the compression system 100 further comprises a stator portion which comprises a first volute 35 developing around the rotating axis R of the centrifugal dual impeller 10, the first volute 35 being fluidly coupled to the plurality of first flow paths 13 and configured to receive the first fluid flow discharged by the plurality of first flow paths 13. In particular, the first volute 35 is fluidly coupled to the trailing edge of the plurality of first blades 12 so to receive the compressed first fluid flow exiting from plurality of first flow paths 13.

[0017] It is to be noted that the volute design of a compressor strongly affects the overall performance, stability, operating range and the location of the best efficiency point of the compressor.

[0018] With non-limiting reference to Fig. 1, the stator portion further comprises a second volute 55 developing around the rotating axis R of the centrifugal dual impeller 10, the second volute 55 being fluidly coupled to the plurality of second flow paths 15 and configured to receive the second fluid flow discharged by the plurality of second flow paths 15. In particular, the second volute 55 is fluidly coupled to the trailing edge of the plurality of second blades 14 so to receive the compressed second fluid flow exiting from plurality of second flow paths 15.

[0019] Advantageously, the first volute 35 further comprises a vane or vaneless diffuser 34, in particular to convert part of the fluid flow energy to pressure. More advantageously, the vane or vaneless diffuser 34may be located immediately downstream of the trailing edge of the plurality of first blades 12.

[0020] In particular, the vane or vaneless diffuser 34 defines a maximum radius rmaxstarting from the rotation axis R (see for example Fig. 1). Advantageously, the second volute 55, in particular the center of gravity of thesecond volute 55, is arranged within the maximum radius rmax.

[0021] Advantageously, also the second volute 55 further comprises a vane or vaneless diffuser, in particular to convert part of the fluid flow energy to pressure. More advantageously, the vane or vaneless diffuser may be located immediately downstream of the trailing edge of the plurality of second blades 14.

[0022] With nonlimiting reference to Fig. 1 and Fig. 3, the first volute 35 may partially overlap the second volute 55 according to a longitudinal direction defined by the rotating axis R. In particular, the first volute 35 and the second volute 55 are designed so that the footprint of the volutes 35 and 55 is minimized and their performance maximized. Advantageously, the second volute 55 may have also a longitudinal development along the rotating axis R (see e.g. Fig. 1). In particular, the longitudinal development of the second volute 55 allows to shift the first system outlet 22 and the second system outlet 42 between each other, so that the output flanges are not interpenetrated (i.e. the output flanges are offset from each other along the longitudinal direction).

[0023] Advantageously, the compression system 100, in particular the stator portion of the compression system 100, further comprises a first system inlet 21 and a first system outlet 22, the first system inlet 21 being fluidly coupled to the to the plurality of first flow paths 13, in particular to the leading edge of the plurality of first blades 12, and the first system outlet 22 being fluidly coupled to the first volute 35 (see e.g. Fig. 1 and Fig. 3). In particular, the first system inlet 21 is configured to receive the first fluid flow to be supplied to the plurality of first flow paths 13 and the first system outlet 22 is configured to discharge the first fluid flow exiting from the first volute 35. It is to be noted that the first system inlet 21 is coaxial with the rotating axis R (i.e. the first fluid flow enters the centrifugal dual impeller 10 with an axial component).

[0024] Advantageously, the compression system 100, in particular the statorportion of the compression system 100, further comprises a second system inlet 41 and a second system outlet 42, the second system inlet 41 being fluidly coupled to the plurality of second flow paths 15, in particular to the leading edge of the plurality of second blades 14, and the second system outlet 42 being fluidly coupled to the second volute 55 (see e.g. Fig. 1 and Fig. 3). In particular, the second system inlet 41 is configured to receive the second fluid flow to be supplied to the plurality of second flow paths 15 and the second system outlet 42 is configured to discharge the second fluid flow exiting from the second volute 55. It is to be noted that the second inlet 41 is not coaxial with the rotating axis R (i.e. the second fluid flow enters the centrifugal dual impeller 10 also with a radial component).

[0025] As mentioned before, there could be different system configurations according to the first and second fluid flows that have to be compressed.

[0026] According to a first possibility, the first system outlet 22 and the second system inlet 41 are fluidly decoupled, so that the first fluid flow discharged by the plurality of first flow paths 13 is not recirculated to the plurality of second flow paths 15. According to this configuration, the first fluid flow may be different from the second fluid flow.

[0027] According to another possibility, the compression system 100 may further comprise a piping system (not shown in any figure) configured to fluidly couple the first system outlet 22 and the second system inlet 41 so that the first fluid flow discharged by the plurality of first flow paths 13 is partially or totally recirculated to the plurality of second flow paths 15; in other words, the second fluid flow received by the second system inlet 41 is partially or totally the first fluid flow discharged by the first system outlet 22. It is to be noted that, if the first fluid flow discharged by the first system outlet 22 is only partially recirculated to the plurality of second flow paths 15, the second fluid flow may be the same fluid of the first fluid flow but has a different mass flow.

[0028] According to another possibility, the second system inlet 41 may be further configured to receive at least one additional fluid flow, so that the second fluid flow is a mixture of partially or totally the first fluid flow discharged by the first system outlet 22 and the at least one additional fluid flow.

[0029] Advantageously, the compression system 100 may further comprise a cooling unit, located along the piping system, configured to remove heat from the first fluid flow discharged by the first system outlet 22, so to reduce the temperature of the first fluid flow recirculated to the second system inlet 41.

[0030] Advantageously, the compression system 100 may further comprise a heating unit, located along the piping system, configured to provide heat to the first fluid flow discharged by the first system outlet 22, so to increase the temperature of the first fluid flow recirculated to the second system inlet 41.

Claims

CLAIMS1. Compression system (100) comprising a centrifugal dual impeller (10) configured to rotate around a rotating axis (R), the centrifugal dual impeller (10) comprising a hub (11), a plurality of first blades (12) having a blade root mechanically coupled to the hub (11) and defining a plurality of first flow paths (13), a shroud (16) mechanically coupled to a blade tip of the plurality of first blades (12), and a plurality of second blades (14) having a blade root mechanically coupled to the shroud (16) and defining a plurality of second flow paths (15), wherein the plurality of first flow paths (13) is configured to compress a first fluid flow, wherein the plurality of second flow paths (15) is configured to compress a second fluid flow, wherein the compression system (100) further comprises a stator potion comprising: a first volute (35) developing around the rotating axis (R), the first volute (35) being fluidly coupled to the plurality of first flow paths (13) and configured to receive the first fluid flow discharged by the plurality of first flow paths (13), and a second volute (55) developing around the rotating axis (R), the second volute (55) being fluidly coupled to the plurality of second flow paths (15) and configured to receive the second fluid flow discharged by the plurality of second flow paths (15).

2. Compression system (100) of claim 1, wherein the first volute (35) further comprises a vane or vaneless diffuser (34).

3. Compression system (100) of claim 2, wherein the vane or vaneless diffuser (34) defines a maximum radius (rmax) from the rotating axis (R), wherein the second volute (55), in particular the center of gravity of the second volute (55), is arranged within the maximum radius (rmax).

4. Compression system (100) of claim 1, wherein the second volute (55) further comprises a vane or vaneless diffuser.

5. Compression system (100) of claim 1, further comprising a first system inlet (21), a second system inlet (41), a first system outlet (22) and a second system outlet (42), wherein the first system inlet (21) and the second system inlet (41) are fluidly coupled respectively to the plurality of first flow paths (13) and to the plurality of second flow paths (15) and the first system outlet (22) and the second system outlet (42) are fluidly coupled respectively to the first volute (35) and to the second volute (55), wherein the first system inlet (21) is configured to receive the first fluid flow to be supplied to the plurality of first flow paths (13) and the second system inlet (41) is configured to receive the second fluid flow to be supplied to the plurality of second flow paths (15).

6. Compression system (100) of claim 5, comprising further a piping system configured to fluidly couple the first system outlet (22) and the second system inlet (41) so that the second fluid flow received by the second system inlet (41) is partially or totally the first fluid flow discharged by the first system outlet (22).

7. Compression system (100) of claim 6, further comprising a cooling unit located along the piping system, wherein the cooling unit is configured to remove heat from the first fluid flow discharged by the first system outlet (22).

8. Compression system (100) of claim 6, further comprising a heating unit located along the piping system, wherein the heating unit is configured to provide heat to the first fluid flow discharged by the first system outlet (22).

9. Compression system (100) of claim 1, wherein the first volute (35) partially overlaps the second volute (55) according to longitudinal direction defined by the rotating axis (R).

10. Compression system (100) of claim 1, wherein the second volute (55) has a longitudinal development along the rotating axis (R).

11. Compression system (100) of claim 1, wherein the centrifugal dual impeller (10) further comprises a second shroud mechanically coupled to a blade tip of the plurality of second blades (14).

12. Compression system (100) of claim 1, comprising a rotating shaft (90) mechanically coupled to the centrifugal dual impeller (10), a wheel gear mechanically coupled to the rotating shaft (90) and a driver mechanically coupled to the wheel gear, wherein the wheel gear is driven by the driver and is configured to transmit motion to the rotating shaft (90) so to drive the centrifugal dual impeller (10).

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