WO2016071415A1

WO2016071415A1 - Centrifugal compressor adjustment system

Info

Publication number: WO2016071415A1
Application number: PCT/EP2015/075742
Authority: WO
Inventors: Simone CORBO; Pawel TWAROWSKI; Marek WATROBSKI; Franco Sarri; Giuseppe Iurisci
Original assignee: Nuovo Pignone Srl
Priority date: 2014-11-07
Filing date: 2015-11-04
Publication date: 2016-05-12
Also published as: ITFI20140248A1

Abstract

The centrifugal compressor comprises a compressor chassis (3) defining an inlet passageway (13), a diffuser (15) fluidly coupled to the inlet passageway, and a return channel (17) extending from the diffuser(15). The compressor further comprises a first impeller (7) rotatably arranged in the chassis (3), between the inlet passageway (13) and the diffuser (15), and a second impeller (9) arranged in the chassis (3) downstream of the return channel (17). Movable inlet guide vanes (21)are arranged in the inlet passageway (13). Movable return guide vanes (25) are arranged in the return channel (17). An actuation system simultaneously moves the movable inlet guide vanes and the movable return guide vanes.

Description

CENTRIFUGAL COMPRESSOR ADJUSTMENT SYSTEM DESCRIPTION FIELD OF THE INVENTION

The present disclosure relates to centrifugal compressors, and in particular to centrifugal compressors provided with a performance adjustment system.

DESCRIPTION OF THE RELATED ART

Multi-stage centrifugal compressors are typically designed to provide the best performance at a design point or design operating condition. The design operating condition is usually the condition at which the compressor is most commonly operated. In other words, the compressor is designed to provide the best performance when it operates in the condition (defined e.g. by pressure difference between inlet and outlet, number of revolutions per minute and flow rate) that will be the most probable during the life time of the compressor.

However, compressors usually do not operate in steady-state conditions. Rather, the operating parameters of the compressor can vary within a relatively wide operating range. It is desirable to adjust the configuration of the compressor to adjust the performance thereof when operating in off-design operating conditions, i.e. in conditions different from those for which the compressor has been designed and under which the compressor provides the highest performance.

In order to ameliorate the off-design performance of a multi-stage compressor, adjustment devices are usually provided in the compressor, and more specifically in the stationary part thereof. In some known centrifugal compressors, movable or adjustable vanes, i.e. movable inlet guide vanes, diffuser vanes and/or return channel vanes are provided. The angle of the movable vanes is adjusted depending upon the operating conditions of the compressor, so as to maximize the performance thereof under off-design condition. Centrifugal compressors are known, wherein separate actuators are provided for adjusting the angular orientation of the movable inlet guide vanes and the movable return channel vanes. These known arrangements are extremely complex, costly and difficult to operate. There is therefore a need for an efficient, though simple and less expensive performance adjustment system for multi-stage centrifugal compressors, aimed at optimizing the off-design performance of the turbomachine.

SUMMARY OF THE INVENTION

Embodiments of the disclosure may provide a centrifugal compressor comprising a compressor chassis defining an inlet passageway, a diffuser fluidly coupled to the inlet passageway, and a return channel extending from the diffuser. The compressor further comprises a first impeller rotatably arranged in the chassis between the inlet passageway and the diffuser. The compressor also comprises at least a second impeller arranged in the chassis downstream of the return channel. A plurality of movable inlet guide vanes are arranged in the inlet passageway and a plurality of movable return guide vanes are arranged in the return channel. An actuation system is drivingly coupled to the movable inlet guide vanes and the movable return guide vanes for simultaneous actuation of the movable inlet guide vanes and the movable return guide vanes. The compressor can be comprised of further compressor stages, each including a rotary impeller and a diffuser. A return channel is located between each diffuser and the subsequent rotary impeller, to deliver gas from the diffuser outlet towards the inlet of the next impeller, for further compression. The last, i.e. the most downstream impeller is provided with a last diffuser, which can be fluidly coupled to a delivery side of the compressor, e.g. through a volute or scroll. Movable return guide vanes can be provided in one, some or all the return channels of the multi-stage centrifugal compressor. The return channel(s) and/or the diffusers can be bladed or un-bladed.

According to a further aspect, disclosed herein is a method for adjusting the performance of a centrifugal compressor, comprising the following steps: providing a compressor chassis defining an inlet passageway, a diffuser fluidly coupled to the inlet passageway, and a return channel extending from the diffuser; providing a first impeller rotatably arranged in the chassis, between the inlet passageway and the diffuser, and a second impeller arranged in the chassis downstream of the return channel; providing a plurality of movable inlet guide vanes in the inlet passageway; providing a plurality of movable return guide vanes in the return channel; simultaneously adjusting an angular position of the movable inlet guide vanes and the movable return guide vanes by means of an actuator. If additional compressor stages are provided, further movable return guide vanes can be arranged in the respective return channels and can be adjusted angularly simultaneously.

Features and embodiments are disclosed here below and are further set forth in the appended claims, which form an integral part of the present description. The above brief description sets forth features of the various embodiments of the present invention in order that the detailed description that follows may be better understood and in order that the present contributions to the art may be better appreciated. There are, of course, other features of the invention that will be described hereinafter and which will be set forth in the appended claims. In this respect, before explaining several embodiments of the invention in details, it is understood that the various embodiments of the invention are not limited in their application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which the disclosure is based, may readily be utilized as a basis for designing other structures, methods, and/or systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

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.l illustrates a partial schematic longitudinal section of a multi-stage centrifugal compressor;

Figs.2 A and 2B illustrate axonometric views of the inlet guide vanes and return guide vanes and relevant actuating elements according to two embodiments of the subject matter disclosed herein; Fig.3 illustrates a front view of the inlet guide vanes;

Fig.4 illustrates a front view of the inlet guide vanes and relevant annular inlet actuation member;

Fig.5 illustrates the annular return actuation member.

DETAILED DESCRIPTION OF EMBODIMENTS The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. Reference throughout the specification to "one embodiment" or "an embodiment" or "some embodiments" means that the particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrase "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout the specification is not necessarily referring to the same embodiment(s). Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

Fig.l illustrates a schematic partial section of a multi-stage centrifugal compressor 1. In the schematic of Fig.l two stages of the multi-stage centrifugal compressor 1 are shown. It shall be understood that the centrifugal compressor can comprise one more additional stages, as known to those skilled in the art. In the embodiment shown in Fig.l, the centrifugal compressor 1 comprises a chassis 3 and a shaft 5, arranged in the chassis 3 for rotation therein. The chassis 3 can comprise a casing portion (not shown) and diaphragms portions 3 A, 3B.

Each compressor stage comprises an impeller arranged on shaft 5 for rotation in the chassis 3. In Fig.l, reference number 7 designates a first impeller of a first compressor stage, and reference number 9 designates a second impeller of a second compressor stage. In the exemplary embodiment of Fig.l the first impeller 7 comprises an impeller hub 7 A, a set of blades 7B and an impeller shroud 7C. The second impeller 9 comprises an impeller hub 9 A, a set of blades 9B and an impeller shroud 9C. The first impeller 7 is arranged between an inlet plenum 11, wherefrom gas is delivered in an annular inlet passageway 13 towards the first impeller 7. Downstream of the first impeller 7 a first diffuser 15 is arranged, extending from the outlet of the first impeller 7 towards a return channel 17. In some embodiments the first diffuser 15 can be bladed, i.e. provided with a plurality of preferably stationary blades arranged therein, not shown.

The return channel 17 extends from the first diffuser 15 towards the inlet of the second impeller 9. The return channel 17 can be provided with stationary blades 17 A.

Downstream of the second impeller 9 a second diffuser 19 is provided, which can extend towards a second return channel, or towards an outlet scroll, not shown, where the compressed gas is collected and where from the gas is delivered towards a compressor outlet (not shown).

According to embodiments disclosed herein, a set of movable inlet guide vanes 21 are movably coupled to the chassis 3 and arranged in the inlet passageway 13. The inlet guide vanes 21 are circularly arranged around a rotation axis A-A of the impellers 7, 9. Each inlet guide vane 21 is pivotally connected to the chassis 3 and the angular position thereof can be adjusted around a respective adjustment axis B-B by means an actuation system globally designated as 23, which will be described in greater detail later on, and the main components whereof are shown in isolation in Figs.2A and 2B. According to embodiments disclosed herein, a set of movable return guide vanes 25 are movably coupled to the chassis 3 and arranged in the return channel 17. The return guide vanes 25 are circularly arranged around the rotation axis A-A of the impellers 7, 9. Each return guide vane 25 is pivotally connected to the chassis 3 and the angular position thereof can be adjusted around a respective adjustment axis C-C by means the actuation system globally designated as 23. Each movable return guide vane 25 can be arranged downstream of a respective return channel blade 17A.

As best shown in Figs. 2, 3 and 4, each inlet guide vane 21 comprises a pivotally arranged blade. Each inlet guide vane 21 can be supported on a first pin 27, which is supported in a stationary annular component 29 of the chassis 3. The annular component 29 is removed in Fig.4. Each first pin 27 can be connected to the respective inlet guide vane 21 in an approximately central position between a leading edge 21 A and a trailing edge 2 IB of the respective inlet guide vane 21.

Each first pin 27 is torsionally constrained to a first actuation arm 31. Each first actuation arm 31 is in turn hinged at a distal end of a respective first actuating rod 33. The proximal end of each first actuating rod 33 is pivotally connected at 33A to an annular inlet actuation member 35. The annular inlet actuation member 35 is mounted in the chassis 3 so as to rotate around an annular actuation member axis, which coincides with the rotation axis A-A of impellers 7 and 9. The angular movement of annular inlet actuation member 35 is shown by double arrow f35 in Fig.4. The angular displacement of the annular inlet actuation member 35 causes the inlet guide vanes 21 to simultaneously pivot around their respective adjustment axes B-B, the motion of the annular inlet actuation member 35 being transmitted to the inlet guide vanes 21 through respective first actuating rods 33, first actuation arms 31 and first pins 27.

In some embodiments the annular inlet actuation member 35 can be pivotally supported in the chassis 3 by means of rollers 37 peripherally arranged around the annular inlet actuation member 35, as best shown in Fig.4.

According to some embodiments, the angular movement according to arrow f35 of the annular inlet actuation member 35 is controlled by means of a drive shaft 39, supported for rotation in the chassis 3. The drive shaft 39 can be substantially parallel to shaft 5. The drive shaft 39 can be mechanically connected to the annular inlet actuation member 35 by means of a first control arm 41, which is torsionally constrained to the drive shaft 39. A distal end 41 A of the first control arm 41 is pivotally connected to a first end of a first connecting rod 43. A second end of the first connecting rod 43 is pivotally coupled at 43A to the annular inlet actuation member 35.

With the above described arrangement, a rotation of the drive shaft 39 around the axis thereof causes a corresponding rotation of the annular inlet actuation member 35 according to double arrow f35 and thus a simultaneous pivoting movement of the inlet guide vanes 21 around their respective adjustment axes B-B. The mechanical connection between drive shaft 39 and the inlet guide vanes 21 form part of the actuation system 23.

As best shown in Figs. 2A, 2B, 3 and 4, each return guide vane 25 comprises a pivotally arranged blade in the chassis 3. Each return guide vane 25 can be supported on a second pin 47, which is supported in a stationary annular component 49 (Fig.5) of the chassis 3. The annular component 49 is removed in Figs.2A and 2B. Each second pin 47 can be connected to the respective return guide vane 25 in an approximately central position between a leading edge 25A and a trailing edge 25B of the respective return guide vane 25. Each second pin 47 is torsionally constrained to a respective second actuation arm 51. Each second actuation arm 51 is in turn hinged at a distal end of a respective second actuating rod 33. The proximal end of each second actuating rod 53 is pivotally connected at 53 A to an annular return actuation member 55. The annular return actuation member 55 is mounted in the chassis 3 so as to rotate around an annular actuation member axis, which coincides with the rotation axis A- A of impellers 7 and 9. The angular movement of annular return actuation member 55 is shown by double arrow f55 in Fig.5. The angular displacement of the annular return actuation member 55 causes the return guide vanes 25 to simultaneously pivot around their respective adjustment axes C-C, the motion of the annular return actuation member 55 being transmitted to the return guide vanes 25 through respective second actuating rods 53, second actuation arms 51 and second pins 47.

In some embodiments the annular return actuation member 55 can be pivotally supported in the chassis 3 by means of rollers 57, which are peripherally arranged around the annular return actuation member 55, as best shown in Figs.2A, 2B and 5.

According to some embodiments, the angular movement according to f55 of the annular return actuation member 55 is controlled by means of the drive shaft 39. The drive shaft 39 can be mechanically connected to the annular return actuation member 55 by means of a second control arm 61, which is torsionally constrained to the drive shaft 39. A distal end 61A of the second control arm 61 is pivotally connected to a first end of a second connecting rod 63. A second end of the second connecting rod 63 is pivotally coupled at 63 A to the annular return actuation member 55.

With the above described arrangement, a rotation of the drive shaft 39 around the axis thereof causes a corresponding rotation of the annular return actuation member 55 according to double arrow £55 and thus a simultaneous pivoting movement of the return guide vanes 25 around their respective adjustment axes C-C. The adjustment movement of the return guide vanes 25 is simultaneous with the adjustment movement of the inlet guide vanes 21, since both movements are controlled by the same drive shaft 39. The rotation of drive shaft 39 can be controlled by an actuator schematically shown at M in Figs. 2A and 2B. The actuator M is arranged differently in the two figures. According to Fig.2A a linear actuator M is connected to the drive shaft 39 by means of a third control arm 69, torsionally constrained to the drive shaft 39, and a drive rod 71, which are hinged to one another. In Fig. 2B the actuator, still labeled M, is a rotating actuator and the rotary shaft thereof is directly connected to the drive shaft 39. In other embodiments the connection between rotating actuator M and drive shaft 39 can be through reduction gears, for instance.

According to further embodiments, not shown, the mechanical connection between the drive shaft 39 and the annular inlet actuation member 35 and annular return actuation member 55 can be obtained e.g. by means of a gear arrangement. Two toothed wheels can be mounted on the drive shaft 39. The first toothed wheel can mesh with teeth provided on the annular inlet actuation member 35, and the second toothed wheel can mesh with teeth provided on the annular return actuation member 55. The annular actuation members 35, 55 can be manufactured in the form of toothed crowns, or a toothed crown can be constrained coaxially with each one of said annular actuation members. Rotation of the drive shaft 39 can also in this case be controlled by a rotary actuator or a linear actuator.

A single actuator M, e.g. an electric motor or the like, can thus be used to control the pivoting movement of both return guide vanes 25 and inlet guide vanes 21, to adjust their angular position depending upon the operating conditions of the multi-stage compressor 1. The flow parameters, in particular the inlet flow angle at the inlet of each impeller 7, 9 can thus be adjusted with as simple control mechanism, to maximize the compressor performance depending upon the operating parameters of the compressor when the latter operates in an off-design condition.

While the disclosed embodiments of the subject matter described herein have been shown in the drawings and fully described above with particularity and detail in connection with several exemplary embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without materially departing from the novel teachings, the principles and concepts set forth herein, and advantages of the subject matter recited in the appended claims. Hence, the proper scope of the disclosed innovations should be determined only by the broadest interpretation of the appended claims so as to encompass all such modifications, changes, and omissions. In addition, the order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments.

Claims

CLAIMS:

1. A centrifugal compressor comprising: a compressor chassis defining an inlet passageway, a diffuser fluidly coupled to the inlet passageway, and a return channel extending from the diffuser; a first impeller rotatably arranged in the chassis between the inlet passageway and the diffuser; at least a second impeller arranged in the chassis downstream of the return channel; a plurality of movable inlet guide vanes, arranged in the inlet passageway; a plurality of movable return guide vanes, arranged in the return channel; an actuation system drivingly coupled to the movable inlet guide vanes and the movable return guide vanes for simultaneous actuation of the movable inlet guide vanes and the movable return guide vanes.

2. The centrifugal compressor of claim 1, wherein the actuation system comprises an annular inlet actuation member mechanically coupled to the movable inlet guide vanes, and an annular return actuation member mechanically coupled to the movable return guide vanes, the annular inlet actuation member and the annular return actuation member being mechanically coupled for simultaneous rotation about an annular actuation member axis.

3. The centrifugal compressor of claim 2, wherein the annular inlet actuation member and the annular return actuation member are mechanically connected to a drive shaft, said drive shaft being controlled by an actuator for simultaneous movement of the movable inlet guide vanes and the movable return guide vanes.

4. The centrifugal compressor of claim 3, wherein a first control arm is torsionally constrained the drive shaft and drivingly connected through a first connecting rod to the annular inlet actuation member.

5. The centrifugal compressor of claim 3 or 4, wherein a second control arm is torsionally constrained to the drive shaft and drivingly connected through a second connecting rod to the annular return actuation member.

6. The centrifugal compressor of any of claims 3 to 5, wherein the drive shaft is drivingly connected to the annular inlet actuation member and to the annular return actuation member through a toothed wheels system.

7. The centrifugal compressor of any one of claims 2 to 6, wherein each movable inlet guide vane is pivotally connected to the compressor chassis through a respective first pin; wherein each first pin is provided with a respective first actuation arm torsionally constrained thereto; and wherein each first actuation arm is pivoted to a distal end of a respective first actuating rod, a proximal end of the first actuating rod being hinged to the annular inlet actuation member, such that rotation of the annular inlet actuation member about the annular actuation member axis causes a simultaneous angular movement of the movable inlet guide vanes around their respective first pins.

8. The centrifugal compressor of claim 7, wherein each first pin is connected to the respective movable inlet guide vane in a position intermediate a leading edge and a trailing edge of the movable inlet guide vane.

9. The centrifugal compressor of any one of claims 2 to 8, wherein each movable return guide vane is pivotally connected to the compressor chassis through a respective second pin; wherein each second pin is provided with a respective second actuation arm torsionally constrained thereto; and wherein each second actuation arm is pivoted to a distal end of a respective second actuating rod, a proximal end of the actuating rod being hinged to the annular return actuation member, such that rotation of the annular return actuation member about the annular actuation member axis causes a simultaneous angular movement of the movable return guide vanes around their respective second pins.

10. The centrifugal compressor of claim 9, wherein each second pin is connected to the respective movable return guide vane in a position intermediate a leading edge and a trailing edge of the movable return guide vane.

11. A method for adjusting the performance of a centrifugal compressor, comprising the following steps: providing a compressor chassis defining an inlet passageway, a diffuser fluidly coupled to the inlet passageway, and a return channel extending from the diffuser; providing a first impeller rotatably arranged in the chassis between the inlet passageway and the diffuser, and a second impeller arranged in the chassis downstream of the return channel; providing a plurality of movable inlet guide vanes in the inlet passageway; providing a plurality of movable return guide vanes in the return channel; simultaneously adjusting an angular position of the movable inlet guide vanes and the movable return guide vanes by means of an actuator.

12. The method of claim 11 , further comprising the following steps: providing an annular inlet actuation member mechanically coupled to the movable inlet guide vanes; providing an annular return actuation member mechanically coupled to the movable return guide vanes; simultaneously rotating the annular return actuation member and the annular inlet actuation member by means of said actuator.

13. The method of claim 11 or claim 12, further comprising the steps of: providing a drive shaft with a shaft axis, mechanically connected to the annular return actuation member and to the annular inlet actuation member; and rotating the annular return actuation member and the annular inlet actuation member by angularly moving the drive shaft around the shaft axis.