Integrally geared turbomachinery system with at least two coaxial impellers having different rotating speeds

Abstract

Integrally geared turbomachinery system (200) comprising a wheel gear (90) configured to rotate around a rotating axis (R), a couple of pinion shafts (10, 20) and an epicyclic gear (50) configured to mechanically couple a first pinion shaft (10) and a second pinion shaft (20). The epicyclic gear (50) comprises a sun gear (51), a plurality of planet gears (52) and a ring gear (53). The first pinion shaft (10) is configured to be mechanically coupled to the wheel gear (90) and to rotate around a first axis (X) at a first rotational speed and the second pinion shaft (20) is configured to rotate around a second axis (Y) at a second rotational speed different from the first rotational speed due to the epicyclic gear (50). The first axis (X) and the second axis (Y) are coincident and parallel to the rotating axis (R).

Description

TITLEIntegrally geared turbomachinery system with at least two coaxial impellers having different rotating speedsDESCRIPTIONTECHNICAL FIELD

[0001] The subject-matter disclosed herein relates to an integrally geared turbomachinery system with at least two coaxial impellers having different rotating speeds.BACKGROUND ART

[0002] Known integrally geared turbomachinery systems consist of a central low-speed wheel (known as “bull gear”) and multiple pinion gears on the outside of it driving multiple impeller shafts. By changing each of the gear ratios, it is possible to operate each impeller shaft at the optimal speed. It is to be noted that, nowadays, the gear ratio allowed by the bull gear is technologically limited, typically around 16-17.

[0003] In order to reduce the footprint of the system, one known configuration is to have two impellers mounted on a single shaft (i.e. provide the shaft with two impellers located at the opposite ends of the shaft). However, since the shaft is rotating at one specific rotational speed, it implies that at least one (or even both) of the two impellers is not fully optimized. For example, if the turbomachinery system is a double-stage compressor system which is driven by the same shaft (i.e. the stages are running at the same rotational speed m) the downstream stage has a reduced flow coefficient (which is calculated asm / pMD3 w^ere m / p is the volumetric flow F) with respect to the upstream stage since the volumetric flow at the downstream stage is less than thevolumetric flow at the upstream stage (Vdown< Vup) due to the fact that the flow processed by the downstream stage has already been processed (i.e. compressed) by the first stage. It is to be noted that the difference between the volumetric flow processed by the stages is particularly evident in case the fluid has good compressibility (e.g. CO2). In any case, since the rotational speed is the same for both impellers, the flow coefficientof the first impeller and / or the flow coefficientof the second impeller may not be the optimal flow coefficientbut instead an unoptimized flow coefficient , thus resulting in a poorly optimized efficiency.

[0004] The same is true also, for example, if an intercooler or a fluid extract! on / inj ection is provided between the upstream stage and the downstream stage. In particular, if the temperature of the processed flow is decreased between the upstream stage and the downstream stage, the same applies to the volumetric flow Vd0Wn < Vup) as p depends on temperature.

[0005] Therefore, it would be desirable to have an integrally geared turbomachinery system with reduced footprint and which has all the impellers operating at the optimal rotating speed without the standard bull gear technological limitations, in order to achieve a higher efficiency.SUMMARY

[0006] According to an aspect, the subject-matter disclosed herein relates to an integrally geared turbomachinery system comprising a wheel gear configured to rotate around a rotating axis, a couple of pinion shafts and an epicyclic gear configured to mechanically couple a first pinion shaft and a second pinion shaft. The epicyclic gear comprises a sun gear, a plurality of planet gears and a ring gear. The first pinion shaft is configured to be mechanically coupled to the wheel gear and to rotate around a first axis at a first rotational speed and the second pinion shaft is configured to rotate around a second axis at a secondrotational speed different from the first rotational speed due to the epicyclic gear. The first axis and the second axis are coincident and parallel to the rotating axis.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] 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 (partial) schematic diagram of an integrally geared turbomachinery system of the prior art, andFig. 2 shows a (partial) schematic diagram of a first embodiment of an innovative integrally geared turbomachinery system with at least two coaxial impellers having different rotating speeds.DETAILED DESCRIPTION OF EMBODIMENTS

[0008] According to an aspect, the subject-matter disclosed herein relates to an innovative integrally geared turbomachinery system, i.e. a turbomachinery system which has several impellers (compressors and / or expanders) driven by a main gear. In order to minimize the footprint, the main gear drives several couple of first and second pinion shafts which have a coincident axis of rotation, each pinion shaft being coupled to an overhung impeller. Therefore, each couple of pinion shaft has a pair of impellers which have a coincident axis of rotation. The innovative turbomachinery system has a first pinion shaft which is coupled to the main gear (therefore rotating at a first speed due to the main gear) and an epicyclic gear which is coupled to the first and second pinion shaft of each couple of pinion shafts and which enable to transmit motion fromthe first pinion shaft to the second pinion shaft, allowing the second pinion shaft to rotate at a different rotating speed with respect to the first pinion shaft. In other words, the innovative system allows to rotate each impeller of the system at a different rotational speed so to rotate each impeller at its optimal speed and therefore to maximize the efficiency of the machines.

[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. l is a partial schematic diagram of a known integrally geared turbomachinery system 100 and Fig. 2 is a partial schematic diagrams of a first embodiment 200 of an innovative integrally geared turbomachinery system with at least two coaxial impellers having different rotating speeds.

[0011] The innovative integrally geared turbomachinery system herein disclosed essentially differs from the prior-art integrally geared turbomachinery system 100 of Fig. 1 in that at least a couple of coaxial impellers of the system can rotate at different rotating speeds, thus allowing each impeller to rotate at its optimal speed and therefore to maximize the efficiency of the machines. In particular, the innovative integrally geared turbomachinery system comprises an epicyclic gear which couple a first impeller and a second impeller, in particular a first shaft of the first impellerand a second shaft of the second impeller, which have coincident rotation axes (or “coaxial”), so that the impellers driven by each couple of coaxial pinion shafts may rotate at different rotating speeds.

[0012] In Figure 2 there is shown, for example and without limitation, an embodiment of an innovative integrally geared turbomachinery system generally indicated with reference numeral 200. The system 200 comprises a wheel gear 90 and a couple of pinion shafts 10 and 20. In particular, the first pinion shaft 10 is mechanically coupled to the wheel gear 90 and mechanically coupled to the second pinion shaft 20, as it will be apparent from the following.

[0013] Firstly, it is to be clarified that Fig. 2 and its relationship with Fig. 1 should not be construed restrictively. Many other embodiments are possible without exiting from the scope of the present disclosure. Furthermore, for the sake of clarity, it is to be noted that Figures 1 and show only a partial schematic diagram of a system: in fact, Figs. 1 and 2 are partial longitudinal views (i.e. longitudinal views of an upper half of the system) and only the rotating parts of the system are shown.

[0014] With non-limiting reference to Fig. 2, the wheel gear 90 is typically driven by a drive shaft 80 which rotates around a rotation axis R. As already mentioned, the first pinion shaft 10 is configured to be mechanically coupled to the wheel gear 90 and to rotate around a first axis X (i.e. the rotation axis X of the first pinion shaft) at a first rotational speed. In particular, the first pinion shaft 10 has a pinion portion 11 which is configured to cooperate with the first portion 91 of wheel gear 90, more in particular the pinion portion 11 engages a toothing of the first portion 91 of wheel gear 90; in other words, the wheel gear 90 transmits a motion to the first pinion shaft 10.

[0015] The system 200 further comprises an epicyclic gear 50 configured to mechanically couple the first pinion shaft 10 to the second pinion shaft 20, soto transmit motion to the second pinion shaft 20. As it will be better described in the following, the second pinion shaft 20 is configured to rotate around a second axis Y (i.e. the rotation axis Y of the second pinion shaft) at a second rotational speed different from the first rotational speed due to the epicyclic gear 50.

[0016] With non-limiting reference to Fig. 2, the first axis X and the second axis Y are coincident; additionally, the first axis X and the second axis Y are parallel to the rotating axis R of the wheel gear 90. In other words, the first pinion shaft 10 and the second pinion shaft 20 may be defined as “coaxial”, as they rotate around a coincident axis.

[0017] According but non-limiting to the embodiment shown in Fig. 2, the epicyclic gear 50 comprises a sun gear 51, a plurality of planet gears 52 and a ring gear 53. In particular, the sun gear 51 is mechanically coupled, in particular fixed, to the first pinion shaft 10 and is configured to rotate at a first rotational speed. In other words, being fixed to the first pinion shaft 10, the sun gear 51 rotates at the same speed of the first pinion shaft 10 due to the motion transmitted by the wheel gear 90.

[0018] Advantageously, the sun gear 51 is mechanically coupled to the plurality of planet gears 52, for example three planet gears 52; in particular, the plurality of planet gears 52 are configured to cooperate with a toothing of the sun gear 51, so that the sun gear 51 transmits a motion to the plurality of planet gears 52. According but non-limiting to the embodiment shown in Fig. 2, the plurality of planet gears 52 are mechanically coupled to the second pinion shaft 20 and are configured to rotate at a second rotational speed. In other words, the plurality of planet gears 52 transmits a motion to the second pinion shaft 20, so that the second pinion shaft 20 rotates at a second rotational speed. For example, the first rotational speed may be 1.5-7 times greater than the second rotational speed.

[0019] Advantageously, the plurality of planet gears 52 is mechanically coupled to the ring gear 53. According but non-limiting to the embodiment shown in Fig. 2, the ring gear 53 is fixed.

[0020] From the embodiment described above, additional variants are possible, without departing from the teaching of the present disclosure. In particular, various epicyclic gears are nowadays known, typically classified as simple epicyclic gears or compound epicyclic gears.

[0021] According to another possibility not shown in any figures, the sun gear 51 may be mechanically coupled, in particular fixed, to the first pinion shaft 10 and rotate at the first rotational speed, the plurality of planet gears 52 may be mechanically coupled to the second pinion shaft 20 and rotate at the second rotational speed and the ring gear 53 may be configured to rotate at a third rotational speed, in particular a third imposed rotational speed. According to a possibility, the ring gear 53 may be mechanically coupled to the wheel gear 90 which may transmit a motion to the ring gear 53. In particular, the ring gear 53 may be mechanically coupled to a portion of the wheel gear 90 which has a different diameter from the portion of the wheel gear which is mechanically coupled to the first pinion shaft 10.

[0022] Advantageously, the first pinion shaft 10 comprises a first impeller 31 mechanically coupled at a first end of the first pinion shaft 10. It is to be noted that the fist impeller 31 may be a compressor or an expander respectively configured to compress a fluid flow or expand a fluid flow, as it will better described in the following. Advantageously, the first impeller 31 is configured to rotate at the first rotational speed; even more advantageously, the first rotational speed is an optimal rotating speed of the first impeller 31 (i.e. a rotating speed adapted to maximize the efficiency of the first impeller).

[0023] Advantageously, the second pinion shaft 20 comprises a second impeller 32 mechanically coupled at a first end of the second pinion shaft 20.It is to be noted that the second impeller 32 may be a compressor or an expander configured to respectively compress a fluid flow or expand a fluid flow, as it will better described in the following. Advantageously, the second impeller 32 is configured to rotate at the second rotational speed; even more advantageously, the second rotational speed is an optimal rotating speed of the second impeller 32 (i.e. a rotating speed adapted to maximize the efficiency of the second impeller).

[0024] As already mentioned, the first impeller 31 and the second impeller 32 are configured to process a fluid flow, in particular compress or expand a fluid flow; it is to be noted that the fluid flow processed by the first impeller 31 and the fluid flow processed by the second impeller 32 may be the same fluid flow or different fluid flows. It is also to be noted that, for the purpose of the present disclosure, “different fluid flows” means fluids which may have different compositions and / or different mass flow, for example due to fluid extractions or fluid injections.

[0025] In particular, with non-limiting reference to Fig. 2, there are four possible configurations:1) the first impeller 31 and the second impeller 32 are both compressors;2) the first impeller 31 is a compressor and the second impeller 32 is an expander;3) the first impeller 31 is an expander and the second impeller 32 is a compressor;4) the first impeller 31 and the second impeller 32 are both expanders.It is to be noted that the first impeller 31 and the second impeller 32 may be fluidly coupled or fluidly decoupled; in particular, if the first impeller 31 and the second impeller 32 are fluidly coupled, the first impeller 31 may process a fluid flow which is then processed by the second impeller 32 (or vice versa).

[0026] According to a first example, with non-limiting reference to the firstconfiguration in which the first impeller 31 and the second impeller 32 are both compressors, the second impeller 32 may receive a fluid flow at a compressor inlet and may be configured to compress it and to discharge a compressed fluid flow at a compressor outlet which is received from the first impeller 31 at a compressor inlet. The first impeller 31 may be configured to further compress the compressed fluid flow from the second impeller 32 and to discharge a more compressed fluid flow at a compressor outlet. In other words, according to this example, the first impeller 31 and the second impeller 32 are fluidly coupled.

[0027] According to a second example, with non-limiting reference to the first configuration in which the first impeller 31 and the second impeller 32 are both compressors, the first impeller 31 may receive a first fluid flow at a compressor inlet and may be configured to compress it and to discharge a compressed first fluid flow at a compressor outlet. The second impeller 32 may be configured to receive a second fluid flow, to compress it and to discharge a compressed second fluid flow at a compressor outlet. In other words, according to this example, the first impeller 31 and the second impeller 32 are fluidly decoupled.

[0028] According to a possibility (not shown in any figure), the system 200, may further comprise a heat exchanger located between the first impeller 31 and the second impeller 32. In particular, with non-limiting reference to the first example disclosed above, the heat exchanger may be located downstream the second impeller 32 and upstream the first impeller 31. Advantageously, the heat exchanger is configured to remove heat from the compressed fluid flow (i.e. the heat exchanger is an “intercooler”). Alternatively, the heat exchanger is configured to provide heat to the expanded fluid flow.

[0029] With non-limiting reference to Fig. 2, the system 200 further comprises at least one bearing 41 and 42 for each pinion shaft 10 and 20. In particular, a first bearing 41 is mechanically coupled to the first pinion shaft10 and is configured to axially support the first pinion shaft 10 and a second bearing 42 is mechanically coupled to the second pinion shaft 20 and is configured to axially support the second pinion shaft 20. It is to be noted that also the epicyclic gear 50 may be further configured to axially support the first and the second pinion shafts 10 and 20.

[0030] As already mentioned, Figure 2 shows only (and partially) the rotary parts of the system 200. Advantageously, the system 200 further comprises a casing (not shown in any figure) configured to enclose at least the wheel gear 90, the pinion shafts 10 and 20, the epicyclic gear 50 and the first and second impeller 31 and 32. In particular, the casing is configured to allow the flowing of fluid to and from the first impeller 31 and the second impeller 32. In other words, the casing may comprise one of more of volute, inlet guide vane unit, vaned or vaneless diffuser, flange and duct, in order to supply a fluid flow to the first impeller 31 and the second impeller 32 and to discharge a fluid flow from the first impeller 31 and the second impeller 32. As already mentioned, the fluid flow of the first impeller 31 and the second impeller 32 may be the same fluid or different fluids.

[0031] Advantageously, the system 200 comprises a plurality of couples of pinion shafts 10 and 20 and a plurality of epicyclic gears 50, each epicyclic gear 50 being configured to mechanically couple the first pinion shaft 10 and the second pinion shaft 20 of each couple of pinion shafts 10 and 20. In particular, the first axis X of the first pinion shaft 10 and the second axis Y of the second pinion shaft 20 are coincident and are located at different angular positions with respect to the wheel gear 90. Advantageously, the different angular positions of the first and second axes X and Y are equally spaced around the wheel gear 90, so that the interferences between the elements of the system, in particular between impellers, are avoided.

Claims

CLAIMS1. Integrally geared turbomachinery system (200) comprising a wheel gear (90) configured to rotate around a rotating axis (R), a couple of pinion shafts (10, 20) and an epicyclic gear (50) configured to mechanically couple a first pinion shaft (10) and a second pinion shaft (20), the epicyclic gear (50) comprising a sun gear (51), a plurality of planet gears (52) and a ring gear (53), wherein the first pinion shaft (10) is configured to be mechanically coupled to the wheel gear (90) and to rotate around a first axis (X) at a first rotational speed, wherein the second pinion shaft (20) is configured to rotate around a second axis (Y) at a second rotational speed different from the first rotational speed due to the epicyclic gear (50), the first axis (X) and the second axis (Y) being parallel to the rotating axis (R), the first axis (X) and the second axis (Y) being coincident.

2. The integrally geared turbomachinery system (200) of claim 1, wherein the sun gear (51) of the epicyclic gear (50) is mechanically coupled to the first pinion shaft (10) and is configured to rotate at the first rotational speed.

3. The integrally geared turbomachinery system (200) of claim 1, wherein the plurality of planet gears (52) of the epicyclic gear (50) are mechanically coupled to the second pinion shaft (20) and are configured to rotate at the second rotational speed.

4. The integrally geared turbomachinery system (200) of claim 1, wherein the ring gear (53) of the epicyclic gear (50) is fixed.

5. The integrally geared turbomachinery system (200) of claim 1, wherein the ring gear (53) of the epicyclic gear (50) is configured to rotate at a third rotational speed.

6. The integrally geared turbomachinery system (200) of claim 1, further comprising a first impeller (31) and a second impeller (32), wherein the first impeller (31) is mechanically coupled at a first end of the first pinion shaft (10) and rotates at the first rotational speed, and wherein the second impeller (32) is mechanically coupled at a first end of the second pinion shaft (20) and rotates at the second rotational speed.

7. The integrally geared turbomachinery system (200) of claim 6, wherein the first impeller (31) is configured to receive a fluid flow, to compress / expand it and to discharge a compressed / expanded fluid flow and the second impeller (32) is configured to receive the compressed / expanded fluid flow from the first impeller (31).

8. The integrally geared turbomachinery system (200) of claim 6, wherein the first impeller (31) is configured to receive a first fluid flow, to compress / expand it and to discharge a compressed / expanded first fluid flow, and wherein the second impeller (32) is configured to receive a second fluid flow, to compress / expand it and to discharge a compressed / expanded second fluid flow.

9. The integrally geared turbomachinery system (200) of claim 8, wherein the first fluid flow and the second fluid flow are the same fluid.

10. The integrally geared turbomachinery system (200, 300) of claim 8, wherein the first fluid flow and the second fluid flow are different fluids.

11. The integrally geared turbomachinery system (200) of claim 6, further comprising a heat exchanger, wherein the heat exchanger is located between the first impeller (31) and the second impeller (32), wherein the heat exchanger is configured to remove / provide heat from / to the compressed / expanded fluid flow.

12. The integrally geared turbomachinery system (200) of claim 1, further comprising at least one bearing (41, 42, 43, 44) for each pinion shaft (10, 20), the bearings (41, 42, 43, 44) being mechanically coupled to the pinion shafts (10, 20) and being configured to axially support the pinion shafts (10, 20).

13. Integrally geared turbomachinery system (200) of claim 1, comprising a plurality of couples of pinion shafts (10, 20) and a plurality of epicyclic gears (50), each epicyclic gear (50) being configured to mechanically couple the first pinion shaft (10) and the second pinion shaft (20) of each couple of pinion shafts (10, 20), wherein the first axis(X) and the second axis (Y) of each couple of pinion shafts (10, 20) are at different angular positions with respect to the wheel gear (90).

14. Integrally geared turbomachinery system (200) of claim 13, wherein the different angular positions are equally spaced.

15. Integrally geared turbomachinery system (200) of claim 6, further comprising a casing configured to enclose at least the wheel gear (90), the pinion shafts (10, 20), the epicyclic gear (50) and to allow the flowing of fluid to and from the first impeller (31) and the second impeller (32).

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