EP3833872A1

EP3833872A1 - Multi-stage turbomachine

Info

Publication number: EP3833872A1
Application number: EP19737111.5A
Authority: EP
Inventors: Jacques BOIGEY
Original assignee: Cryostar SAS
Current assignee: Cryostar SAS
Priority date: 2018-08-07
Filing date: 2019-07-10
Publication date: 2021-06-16
Also published as: CN112424477A; JP2021532302A; US20230340959A1; KR20210040054A; WO2020030373A1; JP7394830B2; FR3084919B1; FR3084919A1; CN112424477B

Abstract

This multi-stage turbomachine comprises: – a central part (2) having at least two bearings (6) from which part there extends at least on one side a shaft (4) guided by said bearings (6) and on which shaft there are mounted, in cantilever fashion, two radial wheels (22, 34), the two radial wheels (22, 34) are separated from one another by a leak-tight partition (32), and each of the two radial wheels (22, 34) is mounted in its casing (24, 32, 40), each casing having a dedicated fluid inlet (24a, 42) and a dedicated fluid outlet (24b, 44).

Description

Multi-stage turbomachine

The present invention relates to a multi-stage turbomachine. It relates more particularly to the structure of such a machine.

A turbomachine can comprise several compression stages or several expansion stages or alternatively at the same time one or more compression stage (s) associated with one or more expansion stage (s).

It is notably known to have a compressor-turbine type machine, also called a compander (word obtained from the English words compressor for compressor and expander for turbine or expander), in which there is one or more centrifugal compressor (s) ( s) and one or more turbine (s). These various stages are mechanically connected to a common motor (possibly a common generator) by means of a set of gears called a gearbox (or its English equivalent, gearbox).

Such a machine makes it possible to obtain excellent performance for the treatment of fluids. It is modular and the same machine can work with one or more fluids: it is for example possible to recover the energy contained in a fluid to transmit it to another fluid.

A disadvantage, however, of known companders is their relatively large footprint.

Another drawback of known companders is their structure, which requires having a large number of steps. There is indeed a bearing for each turbine wheel or compressor as well as four bearings for the engine and the gearbox. This structure also has several trees that must be sealed. All this makes the turbomachine obtained relatively heavy.

Finally, due to the presence of the gearbox, it is most often necessary to have oil to lubricate said gearbox. For some applications, it is preferable not to have oil and the presence of the gearbox is then a drawback.

The object of the present invention is therefore to provide a multi-stage turbomachine which, like the companders, can treat different fluids - for example a gas and a liquid - which do not have all the aforementioned drawbacks.

Thus, the new turbomachine will preferably have a more compact structure. This turbomachine, for equivalent performance, will also be preferably lighter than a compander. Advantageously, this turbomachine will operate without oil.

To this end, the present invention provides a multi-stage turbomachine comprising a central part having at least two bearings from which extends at least on one side a shaft guided by said bearings and on which are cantilevered two radial wheels.

According to the present invention, the two radial wheels are separated from one another by a watertight bulkhead, and each of the two radial wheels is mounted in its casing, each casing having a clean fluid inlet and a clean fluid outlet.

This structure makes it possible to obtain a turbomachine comparable to a compander with four stages with a smaller footprint while allowing to work with several fluids (at least two fluids since at least two casings each have their own inlet and outlet, that is to say not common with another floor.

To facilitate the feeding of the two radial wheels and have a compact structure, the two radial wheels mounted on the same overhang are for example mounted back to back. One wheel is fed on one side and the other on the opposite side.

To limit the number of parts and have a compact structure, provision may be made for the watertight partition to form a wall common to each of the two housings.

To allow the use of fluids at significantly different temperatures, the bulkhead advantageously has thermal insulation.

A multi-stage turbomachine as described above is intended to be used in a thermodynamic process. For better control of this process, it is advantageous to provide that the central part also includes an electric group chosen from all electric motors and electric generators.

According to an advantageous embodiment, the casing corresponding to the distal wheel has a proximal part common with the casing of the proximal wheel and a distal part fixed to the casing of the proximal wheel.

To obtain a structure equivalent to a compander, a multi-stage turbomachine as described above can comprise on either side of its central part a set of two radial wheels separated from each other by a watertight bulkhead , and for each set each of the radial wheels is mounted in its casing, each casing having a clean fluid inlet and a clean fluid outlet.

Details and advantages of the present invention will become more apparent from the description which follows, made with reference to the appended diagrammatic drawing on which:

FIG. 1 is a cross-sectional view of a multi-stage turbomachine, and

FIG. 2 is a partial cross-section view on an enlarged scale of an alternative embodiment of the turbomachine of FIG. 1.

In the embodiment illustrated in FIG. 1, there is a turbomachine with four independent stages. The overall structure of this machine is described below. An electric group 2, which can be a motor or a generator, is placed in the central position. It is crossed by a shaft 4 supported by bearings 6 and having overhanging shaft ends. Each end of the shaft has two radial wheels.

The electrical group 2 is mounted in a housing 8. A magnet 10 is firetté on the shaft 4 and forms the rotor of the electrical group 2. A stator 12, separated from the rotor by an air gap and having windings, is mounted fixed in the box 8. A connection box 14 makes it possible to electrically connect the electrical group 2.

The housing 8 is closed on each side by a cover 16 which incorporates a bearing 6 which is here a hydrodynamic bearing. The housing 8 incorporates an oil collector 18. To avoid any migration of oil to the electrical group 2, seals 22 are provided inside each cover 16.

The bearings 6 of the shaft 4 are thus integrated into the covers 16. The parts of the shaft 4 extending outside the housing 8 (or more precisely of its covers 16) are arranged in overhang relative to the support of this tree 4.

Note in Figure 1 that the two sets of radial wheels arranged on either side of the electrical group 2 are symmetrical. Thus, in the description which follows, only one assembly, the one on the right in FIG. 1, will be described.

A first compressor is mounted adjacent to the cover 16 situated on the right in FIG. 1. This compressor comprises a first compressor wheel 22 and a first compression body in several parts.

The first compressor wheel 22 is mounted on the shaft 4 and driven by it. The fluid (in gas or liquid phase) enters the first compressor wheel 22 in an axial direction (given by the axis of the shaft 4), from left to right in FIG. 1. In the embodiment preferred illustrated in FIG. 1, the shaft 4 has a section of so-called polygonal shape at the level of the first compressor wheel 22. The section of the shaft 4 is here of triangular shape (with faces slightly convex and rounded tops).

The first compression body guides the fluid supplying the first compressor wheel 22 upstream and downstream of the latter. A casing 24 has an inlet 24a which channels the fluid supplying the first compressor wheel 22 in a radial direction as well as an outlet 24b which guides the compressed fluid downstream of the first compressor wheel 22. The casing 24 is fixed to a support 26 mounted on the corresponding cover 16. This support 26 has an inner wall which also participates in guiding the fluid to lead it to the first compressor wheel 22. A sealing part 28 is disposed between the support 26 and the shaft 4 to seal the compressor. In the illustrated embodiment, the sealing piece 28 has a labyrinth on the side of the shaft 4. On the inside side of the casing 24, the sealing piece guides the fluid to pass it from a radial direction towards its axial direction to supply the first compressor wheel 22. Finally, inside the casing 24, a deflector 30 provides the fluid guidance upstream of the first compressor wheel 22 and opposite it .

After the first compressor wheel 22, that is to say moving away from the central part of the turbomachine which integrates the electrical group 2, a transverse wall 32 separates the first compressor from a second compressor. This second compressor has a second compressor wheel 34 as well as a compression body also in several pieces.

The transverse wall 32, as suggested by its name, extends perpendicular to the axis of the shaft 4. It has an annular shape and houses in its center a sealing device 36. At this level, the shaft 4 also has a polygonal (triangular) section. To make the seal, a ring having an inner surface matching the polygonal shape of the shaft 4 and a circular cylindrical outer surface is placed around the shaft 4. The seal is then for example produced on said ring by a system sealing labyrinth.

The transverse wall 32 has a face receiving the rear face of the first compressor wheel 22 and a face receiving the rear face of the second compressor wheel 34. Here the rear face of a wheel is its face of larger diameter. As can be seen here, the two compressor wheels (first compressor wheel 22 and second compressor wheel 34) are thus mounted back-to-back. Each face of the transverse wall 32 has a housing for receiving the rear face of the wheel. corresponding compressor. Beyond this housing, each face of the transverse wall 32 forms a wall for the diffuser of the corresponding compressor.

The casing 24 is configured on the rear side of the first compressor wheel 22 to receive the transverse wall 32. It has for this purpose a hollow housing, preferably with a shoulder 38, to receive the transverse wall 32. The housing at the bottom which takes place the transverse wall 32 is closed by a plate 40 carrying an inlet pipe 42 of fluid and an outlet pipe 44. The plate 40 is fixed on the casing 24.

The inlet manifold 42 is positioned in the central position and it guides fluid towards the second compressor wheel 34 so that this fluid is oriented axially, pointing towards FIG. 1, for the second compressor wheel 34 on the right, from right to left. Inside the housing, a guide 46 guides the fluid to the second compressor wheel 34 and in this wheel. At the wheel outlet, the compressed fluid is guided by a diffuser 48 (and by the transverse plate 32).

The second compressor wheel 34 is also mounted on a section of the shaft 4 having a polygonal section. Note, however, that the second compressor wheel 34 is mounted on a section of dimensions ("diameter") less than the section of the shaft 4 receiving the first compressor wheel 22. A screw 50 comes to fix the second compressor wheel 34 at the end of the shaft 4. By this fixing, the various elements arranged on the shaft 4 are secured by stacking, such as the sealing devices and the first compressor wheel 22.

It is noted here that the two compression bodies are both nested one in the other, with common elements, and at the same time independent since two distinct fluid circuits are created.

In this way, two entirely independent stages are produced, one on the same end of the shaft of a turbomachine.

Figure 2 illustrates an alternative embodiment of Figure 1. It uses the references of Figure 1 to designate similar parts. Here we find two radial wheels separated by a partition and mounted back to back, the two wheels being mounted on the same overhang of a tree. We also find in Figure 2, which is a partial section on an enlarged scale, a bearing (which in this example is also a hydrodynamic bearing but which could be of any other type, “classic” with bearings or magnetic, air , ...). In addition, the compressor body corresponding to the first compressor wheel or proximal wheel (closest to the bearing) is of suitable shape and has a housing for partially receiving the compressor body corresponding to the second compressor wheel. In the following, only the differences between the embodiment of Figure 2 and that of Figure 1 will be highlighted.

On the side of the central part, the cover 16 and the support 26 in FIG. 1 are both grouped in a single piece on which the casing 24 is mounted. The structure of the hydrodynamic bearing and of the seal is reviewed. The sealing part therefore has a different shape.

The embodiment of Figure 2 corresponds for example to a turbomachine intended to work with two fluids at very different temperatures. One then recognizes an insulating layer 52 which is arranged in the second compression body opposite the first compression body. It is possible here, for example, to compress a cryogenic fluid and another fluid at “normal” temperature, for example close to ambient temperature.

The pressure in the second compression body in this other embodiment is relatively high. Therefore, the plate 40 closing this body and separating it from the outside is domed. The fluid supply is then adapted.

The embodiments described above therefore have multi-stage turbomachines, said stages possibly being independent of each other.

Figure 1 illustrates a four-stage machine which is symmetrical. This symmetry is only illustrative. There can be two distinct sets on either side of the central part of the machine.

The turbomachine proposed here has a single shaft and no gearbox. It can thus have a limited footprint compared to a “compander” type machine described in the preamble. The number of bearings and seals to achieve is reduced compared to a "compander".

The turbomachine, in its version proposed with four stages (one could have for example only two or three stages, that is to say two stages on one side and one or zero on the other) or on the contrary more floors.

The proposed turbomachine may also include one or more expansion wheels (and not only compression stages). It then takes place in a thermodynamic installation. It can be a motor if a motor is arranged in the central part, or alternatively generator if a generator is provided in the central part. It can also be an exchange between fluids, one or more regulators then transmitting energy to one or more compressors via the central shaft. For a machine with four stages, one can thus have several configurations depending on whether one has compressors or expansion turbines (or "expanders"). We can thus have the following configurations with a motor:

Turbine-turbine / motor / compressor-compressor

Turbine-turbine / engine / turbine-compressor

Turbine-compressor / motor / compressor-compressor

Turbine-compressor / engine / turbine-compressor

Compressor-turbine / motor / compressor-compressor

Compressor-turbine / engine / turbine-compressor

Compressor-turbine / engine / turbine-turbine

Compressor compressor / motor / compressor-compressor

Similarly with a generator in the central part, we can have all the possible combinations of turbine and compressor on either side of the generator (except having only compressors which cannot then drive the generator).

Similarly, all combinations of turbines and compressors (except only turbines or only compressors) can be envisaged without an electrical group in the central part to carry out energy exchanges between fluids only through the central shaft.

We find each time, at least on one side of the central part, an assembly of two radial wheels, preferably mounted back-to-back, on the same overhang of a common shaft, a sealing device between the two radial wheels. The compression or expansion bodies corresponding to these two radial wheels are produced so that each can receive a different fluid. Each body thus has an inlet and an outlet for fluid and there are two completely separate circuits, the inlet and outlet of one body and the inlet and outlet of the other body.

In the purely descriptive and non-limiting description, the radial wheels shown are mounted on the shaft by zones of the “polygon” type. Of course, other assemblies are possible: keys, teeth, Hirth type teeth, etc.

The outermost wheel is preferably, but not necessarily, mounted on a smaller shaft section. An assembly on two identical sections can also be envisaged. The wheels are assembled using any means: support washers, sockets, labyrinth seal or other, ....

The compression or expansion body corresponding to the outermost wheel, or distal wheel, is preferably fixed to the body (compression or expansion) corresponding to the innermost wheel. Thermal insulation can be provided between the two bodies.

The present invention is not limited to the embodiments described above and to the variants envisaged. It also relates to alternative embodiments within the reach of the skilled person within the scope of the claims below.

Claims

1. Multi-stage turbomachine comprising a central part (2) having at least two bearings (6) from which extends at least on one side a shaft (4) guided by said bearings (6) and on which are cantilever mounted two radial wheels (22, 34),

characterized in that the two radial wheels (22, 34) are separated from each other by a watertight partition (32), and

in that each of the two radial wheels (22, 34) is mounted in its casing (24, 32, 40), each casing having its own fluid inlet (24a, 42) and a fluid outlet (24b, 44) clean.

2. Multi-stage turbomachine according to claim 1, characterized in that the two radial wheels (22, 34), mounted on the same overhang are mounted back to back.

3. Multi-stage turbomachine according to one of claims 1 or 2, characterized in that the watertight partition (32) forms a wall common to each of the two housings (24, 32, 40).

4. Multi-stage turbomachine according to one of claims 1 to 3, characterized in that the watertight bulkhead (32) has thermal insulation (52).

5. Multi-stage turbomachine according to one of claims 1 to 4, characterized in that the central part (2) further comprises an electric group chosen from the group of electric motors and electric generators.

6. Multi-stage turbomachine according to one of claims 1 to 5, characterized in that the casing (32, 40) corresponding to the distal wheel (34) has a proximal part (32) common with the casing of the proximal wheel (22) and a distal part (40) fixed on the casing (24) of the proximal wheel (22).

7. Multi-stage turbomachine according to one of claims 1 to 6, characterized in that it comprises on either side of its central part (2) a set of two radial wheels (22, 34), separated l '' from one another by a watertight partition (32), and in that for each set each of the radial wheels (22, 34), is mounted in its casing (24, 32, 40), each casing having an inlet for clean fluid (24a, 42) and a clean fluid outlet (24b, 44).