Multi-stage compressor

Abstract

To provide a novel type of multi-stage compressor designed as radial compressor or diagonal compressor.SOLUTION: A multi-stage compressor (10), namely a multi-stage radial compressor or a multi-stage diagonal compressor, has a compressor rotor, in which the compressor rotor comprises a rotor shaft (12) and a plurality of impellers (11) which are fastened to the rotor shaft (12), and subjected to inflow in an axial direction and to outflow in a radial direction or diagonal direction. Each impeller (11) comprises: a curved inner shroud (14); a curved outer shroud (15); and a plurality of curved impeller blades (16) arranged between the inner shroud (14) and the outer shroud (15). The inner shroud (14), the outer shroud (15), and the impeller blades (16) each consists of a fibre composite material. The rotor shaft (12) extends through a recess (13) in the inner shroud (14) of each impeller (11).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multi-stage compressor. [Background technology]

[0002] Among thermofluid machines, a distinction is made between compressors on the one hand and steam turbines and gas turbines on the other hand. Fluid machines are also called turbomachines. Among compressors, a distinction is made between axial compressors, radial compressors, and diagonal compressors. Furthermore, among axial compressors, radial compressors, and diagonal compressors, a distinction is made between single-stage compressors and multi-stage compressors. The present invention relates to a multi-stage compressor, i.e., a multi-stage radial compressor or a multi-stage diagonal compressor.

[0003] To compress light gases, such as hydrogen or helium, the compressor must operate at high peripheral speeds to allow efficient compression. Multi-stage radial or diagonal compressors known to date are made of metal and are only conditionally suitable for operating at the high peripheral speeds required to compress light gases.

[0004] Patent Document 1 discloses a radial compressor impeller manufactured as a composite material impeller using a resin transfer molding (RTM) method, where the impeller is made of a fiber composite material, i.e., fibers embedded in a resin.

[0005] Patent Document 2 discloses an impeller for a turbomachine having a plurality of blades, the inner walls of which are connected to a fabric element including a fiber structure woven in a pattern. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] German Patent Application Publication No. 112011100312 [Patent Document 2] European Patent No. 2504581 Summary of the Invention [Problem to be solved by the invention]

[0007] There is a need for a new type of multi-stage compressor, designed as a radial or diagonal compressor, which can be operated at high peripheral speeds and is therefore suitable for compressing light gases. Starting from this, the object of the present invention is based on creating a new type of multi-stage compressor, designed as a radial or diagonal compressor. [Means for solving the problem]

[0008] This object is achieved by a multi-stage compressor as set forth in claim 1. According to the present invention, each impeller comprises a curved inner shroud, a curved outer shroud, and a plurality of curved impeller blades arranged between the inner and outer shrouds, the inner shroud, the outer shroud, and the impeller blades each being made of a fiber composite material, and the rotor shaft extends through a recess in the inner shroud of each impeller. The inner shroud may also be called a hub shroud, and the outer shroud may also be called a cover shroud. The curved impeller blades may be twisted in three dimensions.

[0009] This invention proposes for the first time a multi-stage compressor designed as a radial or diagonal compressor. The impeller has a curved inner shroud, a curved outer shroud, and a plurality of curved, particularly three-dimensionally twisted, impeller blades arranged between the curved inner and outer shrouds, all made of fiber composite material. The rotor shaft extends through a recess in the inner shroud of each impeller. Such a multi-stage compressor can operate at high peripheral speeds. Therefore, such a compressor is suitable for compressing hydrogen gas or other light gases, such as helium gas, natural gas, ammonia, neon, or a mixture of at least two such gases.

[0010] The impeller blades, inner shroud and outer shroud may be integral parts of each impeller in a one-piece design.

[0011] Preferably, the impeller blades, the inner shroud, and the outer shroud are separate components of the respective impellers formed with a differential design, and the impeller blades are connected to the inner shroud and the outer shroud at least via an integral and / or positive connection. Optionally, the impeller blades can additionally be connected to the inner shroud and the outer shroud via mechanical connection elements. To facilitate the manufacture of the multi-stage compressor according to the present invention, it is advantageous for the impeller blades, the inner shroud, and the outer shroud to be formed as separate components connected at least via an integral connection. Such impellers formed with a differential design can operate at high peripheral speeds and are easier to manufacture compared to impellers of an integral design.

[0012] Preferably, each impeller is connected to the rotor shaft via at least a non-positive connection. Optionally, each impeller can additionally be connected to the rotor shaft via an integral and / or positive connection. This provides a particularly advantageous connection of each impeller to the rotor shaft, thereby providing a multi-stage compressor that can operate at high peripheral speeds.

[0013] Preferably, the fiber composite material of the inner shroud contains high-stiffness fibers in the connection region to the rotor shaft, and the fiber composite material of the inner shroud outside the connection region to the rotor shaft, as well as the fiber composite material of the outer shroud and impeller blades, contain high-strength fibers. Thus, each impeller contains different fibers, i.e., high-stiffness fibers on the one hand and high-strength fibers on the other hand. High-stiffness fibers are used in the region of the inner shroud of each impeller, i.e., in that part of the inner shroud that serves for connection to the rotor shaft. In other parts of the inner shroud, as well as in the region of the outer shroud and impeller blades, the fiber composite material preferably contains high-strength fibers. Finally, the impeller can be firmly fixed to the rotor shaft of a multi-stage compressor to ensure high peripheral speeds. Additionally, any combination of the aforementioned fiber types is possible in the aforementioned regions, especially in the transitions between the aforementioned regions.

[0014] Preferably, the inner shroud includes axially extending fibers and tangentially extending fibers in its connection region to the rotor shaft, and includes radially extending fibers and tangentially extending fibers outside the connection region to the rotor shaft. Alternatively or additionally, the inner shroud includes fibers extending in at least one principal stress direction of the inner shroud, in particular fibers extending in a tensile stress direction and / or fibers extending in a compressive stress direction. Such fiber orientation allows the impeller to withstand high loads, which ultimately allows the respective multi-stage compressor to operate at high peripheral speeds.

[0015] Preferred further developments of the invention emerge from the subclaims and the following description. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of an impeller region of a multi-stage compressor according to the present invention; [Figure 2] 1 is a perspective view of an impeller of a multi-stage compressor according to the present invention; [Figure 3] FIG. 3 is an exploded view of the impeller of FIG. 2. [Figure 4] The impeller blades of the impeller in Figure 2. [Figure 5] FIG. 3 shows a detail of the inner shroud of the impeller of FIG. 2, namely, fiber orientation. [Figure 6] FIG. 3 shows further details, namely the fiber orientation and the course of the principal stress directions of the inner shroud of the impeller of FIG. 2. [Figure 7] 3 is a cross-sectional view of the inner shroud of the impeller of FIG. 2 with further details, namely, a fiber layer. [Figure 8] FIG. 3 shows further details, namely the profile of the impeller blades of the impeller of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these.

[0018] 1 shows an excerpt of a cross-sectional view of an impeller 11 region of a multi-stage compressor 10 according to the present invention, which is arranged on a rotor shaft 12 of the compressor 10. A plurality of such impellers 11 are arranged one behind the other on the outer periphery of the rotor shaft 12 as viewed in the axial direction A.

[0019] The rotor shaft 12 forms the rotor of the compressor together with the impeller 11, and is rotatably mounted within a compressor housing of the multi-stage compressor 10 (not shown).

[0020] According to the present invention, the compressor 10 is a multi-stage radial or diagonal compressor, so that the gas to be compressed flows into the impeller 11 in the axial direction A and flows out of the impeller 11 in the radial direction R, i.e., obliquely to the radial direction R.

[0021] Each impeller 11 of the multi-stage compressor 10 includes a curved or arched inner shroud 14, a curved or arched outer shroud 15, and a plurality of curved or arched impeller blades 16 disposed between the inner shroud 14 and the outer shroud 15.

[0022] The inner shroud 14 , outer shroud 15 , and impeller blades 16 of each impeller 11 are each made of fiber composite material, and the rotor shaft 12 extends through a recess 13 in the inner shroud 14 of each impeller 11 .

[0023] The inner shroud 14 may also be referred to as a hub shroud, and the outer shroud 15 may also be referred to as a cover shroud. The curved or arched impeller blades 16 are twisted in three dimensions.

[0024] As already explained, each impeller 11, and therefore its impeller blades 16, experiences an axial inflow A and a radial or diagonal outflow R.

[0025] The impeller blades 16, inner shroud 14 and outer shroud 15 may each be made of fiber composite material and be an integral part of the respective impeller 11 formed in a one-piece design.

[0026] However, in order to allow for easy manufacture of each impeller 11, it is preferred that the inner shroud 14, the outer shroud 15 and the impeller blades 16 are each embodied as separate components of the impeller 11 formed with a differential design, with the impeller blades 16 being connected to the inner shroud 14 on the one hand and to the outer shroud 15 on the other hand via at least an integral connection.

[0027] Thus, the impeller blades 16, together with the differentially designed impeller 11, are integrally connected to the inner shroud 14 and the outer shroud 15 at least via adhesive connections, and if necessary, the impeller blades 16 are additionally connected to the inner shroud 14 and the outer shroud 15 via mechanical connecting elements such as bolts, rivets or screws.

[0028] In the case of thermoplastic materials, the integral connection of the impeller blades 16 to the inner shroud 14 and outer shroud 15 can also be achieved by welding.

[0029] 4 shows the impeller blade 16 alone, which is designed as a double T-shaped cross section, the free leg 17 of which is connected to the inner shroud 14 and the outer shroud 15 at least by adhesive bonding and also by mechanical connecting elements, as described above.

[0030] Preferably, the bonding of each impeller blade 16 in the region of the free leg 17 to the inner shroud 14 and the outer shroud 15 is carried out over the entire surface area in the region of the respective free leg 17 .

[0031] In addition, the mechanical connection element extends through the free leg 17 and through the inner shroud 14 and the outer shroud 15, thereby providing additional connections, particularly to counteract so-called peeling of the shrouds 14, 15 under operating loads and to increase the load capacity of the impeller 11.

[0032] The impeller blades 16 can be embodied in a unitary or differential design. In the exemplary embodiment shown in Figure 4, the impeller blades 16, with a double T-shaped cross section, are embodied in a differential design and are formed from two U-shaped profiles 18 arranged back to back with free legs 17 extending away from a central portion 19 connecting the free legs 17 forming the back surface of the U-shaped profiles 18. The central portions 19 of the U-shaped profiles 18 are then at least integrally connected by gluing and optionally also via mechanical connecting elements such as bolts, rivets or screws.

[0033] Although it is preferred that the cross section of the double T-shaped impeller blade 16 comprises U-shaped profiles 18 arranged back to back, it is also possible to have a double T-shaped impeller blade 16 comprising a single central portion 19 from which the free legs 17 extend away as shown in Figure 4. Figure 8 shows in cross section an extract from a double T-shaped impeller blade 16 with a single central portion 19, in which an insert or core 20 of plastic, fiber composite material, foam rubber, etc. can be arranged in the transition region between the central portion 19 and the free legs 17.

[0034] As previously described, rotor shaft 12 extends through a recess 13 in each impeller 11 of multi-stage compressor 10. Each impeller 11 is seated on rotor shaft 12 with an impeller seat formed by an inner shroud 14.

[0035] The rotor shaft 12 is preferably made of a metallic material, but can also be made of a fiber composite material. In particular, if the rotor shaft 12 is made of a metallic material, for example a steel material, the impeller 11 is connected to the rotor shaft 12 at least via a frictional connection, for example a press-fit connection.

[0036] To form such a press-fit connection, the rotor shaft 12 of metallic material is cooled and introduced in its cooled state into the recess 13 of the impeller 11, and following heating of the rotor shaft 12, a press-fit connection between the rotor shaft 12 and the impeller 11 is formed.

[0037] In addition to the friction connection, each impeller 11 may additionally be connected to the rotor shaft 12 via an integral connection, such as an adhesive connection, and / or a positive connection, such as for example a profile connection or a dowel pin connection.

[0038] As already explained, the inner shroud 14, the outer shroud 15 and the impeller blades 16 are manufactured from a fiber composite material. The fiber composite material of the inner shroud 14 preferably comprises high-stiffness HT fibers in the connection region to the rotor shaft 12, i.e., in the portion 14a extending in the axial direction A, which defines the recess 13 of each impeller 11 for the passage of the rotor shaft 12. In the other portion 14b extending in the radial direction R, the fiber composite material of the inner shroud 14 preferably comprises high-strength HT fibers. The fiber composite material of the outer shroud 15 and the impeller blades 16 also preferably comprises high-strength HT fibers. A combination of different types of fibers can also be used in the aforementioned regions or portions.

[0039] 5 and 6 show possible courses of the fibers in the region of the inner shroud 14, i.e. in the region of the part 14b of the inner shroud 14, which extend outside the connection region 14a to the rotor shaft 12 in the radial direction R. According to Fig. 5, the fibers 21 outside the connection region 14a of the inner shroud 14 extend in the radial direction R, and further fibers 22 extend tangentially or circumferentially. In the region of the part 14a, i.e. in the connection region of the inner shroud 14 to the rotor shaft 12, the fibers 21 extend axially and the fibers 22 extend tangentially or circumferentially. This is not shown in Figs. 5 and 6.

[0040] According to FIG. 6, the fibers outside the connection region 14a of the inner shroud 14 extend in at least one principal stress direction of the portion 14b of the inner shroud 14 extending in the radial direction R, i.e., at least one fiber 23 extends in the tensile direction and at least one fiber 24 extends in the compressive direction of the inner shroud 14 outside the connection region 14a of the inner shroud 14 to the rotor shaft 12.

[0041] Although Figure 6 only shows fibers 23 extending in the tensile direction and fibers 24 extending in the compressive direction, it is clear that when viewed around the circumference, there may be multiple such fibers 23, 24 extending in the principal stress direction.

[0042] The fiber routing of FIG. 5 can be combined with the fiber routing of FIG. 6, i.e., with multiple layers of fibers placed on top of each other.

[0043] FIG. 7 shows a cross section through the inner shroud 14 in the direction of an axial cut, from which it is clear that the inner shroud 14 in sections 14a, 14b contains multiple layers of fibers 21, 22.

[0044] 7, an innermost layer of tangentially or circumferentially extending fibers 22 is formed in the region of the connection 14a of the inner shroud 14 to the rotor shaft 12. A layer of axially extending fibers 21 is disposed thereon, with these fibers 21 in portion 14b extending in the radial direction R and, in the illustrated exemplary embodiment, forming the innermost layer of fibers of portion 14b. Two layers of fibers 22 extending in the tangential or circumferential direction R are disposed on top of this layer of fibers 21 extending in the region of axial portion 14a and radial portion 14b, with a core 25, e.g., of plastic, fiber composite material, foam rubber, or the like, disposed between these two layers of fibers 22 in the transition region between portions 14a and 14b. The outermost layer of fiber 21 in the region of portion 14a of the inner shroud 14 and the region of portion 14b of the inner shroud 14 is formed by fiber 21, which in portion 14a extends in the axial direction A of the inner shroud 14 and thus the impeller 11, and in portion 14b extends in the radial direction R of the inner shroud 14 and thus the impeller 11.

[0045] The outer shroud 15 may also be made of a fiber composite material and may include axially and / or radially and / or tangentially or circumferentially extending fibers.

[0046] The multi-stage compressor 10 of the present invention can ensure high peripheral speeds. Therefore, the multi-stage compressor 10 is particularly suitable for compressing light gases such as hydrogen gas, helium gas, natural gas, ammonia, neon, or mixtures of such gases. Therefore, the multi-stage compressor 10 of the present invention is preferably utilized for compressing and / or transporting such gases or gas mixtures.

[0047] The matrix material of each fiber composite material can be a resin such as an epoxy resin or a thermoplastic resin such as PEEK, and the fibers are preferably carbon fibers. [Explanation of symbols]

[0048] 10 Compressor 11 Impeller 12 rotor shaft 13 Recess 14 Inner shroud 15 Outer shroud 16 impeller blades 17 legs 18 U-profile 19 Central part 20 cores 21 Fiber 22 Fiber 23 Fiber 24 Fiber 25 cores A axis direction R Radial direction

Claims

1. A multi-stage compressor (10), i.e. a multi-stage radial compressor or a multi-stage diagonal compressor, 1. A multi-stage compressor comprising: a compressor rotor, the compressor rotor having a rotor shaft (12) and a plurality of impellers (11) fixed to the rotor shaft (12) and having an axial inflow and a radial or diagonal outflow, each impeller (11) including a curved inner shroud (14), a curved outer shroud (15), and a plurality of curved impeller blades (16) disposed between the inner shroud (14) and the outer shroud (15), the inner shroud (14), the outer shroud (15), and the impeller blades (16) each being made of a fiber composite material, the rotor shaft (12) extending through a recess (13) in the inner shroud (14) of each of the impellers (11).

2. 2. The multi-stage compressor of claim 1, wherein the impeller blades (16), the inner shroud (14) and the outer shroud (15) are integral parts of the respective impellers (11) formed in a one-piece design.

3. 2. The multi-stage compressor of claim 1, wherein the impeller blades (16), the inner shroud (14), and the outer shroud (15) are separate components of each impeller (11) formed in a differential design, and these components are connected via at least an integral connection.

4. 4. The multi-stage compressor of claim 3, wherein the impeller blades (16) are connected to the inner shroud (14) and the outer shroud (15) at least via adhesive connections.

5. 5. A multi-stage compressor according to claim 4, characterized in that the impeller blades (16) are additionally connected to the inner shroud (14) and the outer shroud (15) via mechanical connecting elements, in particular bolts, rivets or screws.

6. 6. The multi-stage compressor according to claim 1, wherein the rotor shaft (12) made of a metal material or a fiber composite material and each impeller (11) are connected at least via a frictional connection.

7. 7. A multi-stage compressor according to claim 6, characterized in that the rotor shaft (12) and each impeller (11) are connected via a press-fit connection.

8. 8. A multi-stage compressor according to claim 6 or 7, characterized in that the rotor shaft (13) and each impeller (11) are further connected via an integral connection and / or a positive connection.

9. the fiber composite material of the inner shroud (14) includes high stiffness fibers in the connection region (14a) to the rotor shaft (12); 9. The multi-stage compressor according to claim 1, wherein the fiber composite material of the inner shroud (14) outside the connection area (14a) to the rotor shaft (12) and the fiber composite material of the outer shroud (15) and impeller blades (16) comprise high strength fibers.

10. the fiber composite material of the inner shroud (14) at the connection region (14a) to the rotor shaft (12) further comprises high strength fibers; 10. The multi-stage compressor of claim 9, wherein the fiber composite material of the inner shroud (14) outside the connection area (14a) to the rotor shaft (12) and the fiber composite material of the outer shroud (15) and the impeller blades (16) further comprise high stiffness fibers.

11. the inner shroud (14) includes the axially extending fibers and the tangentially extending fibers in the connection region (14a) of the inner shroud (14) toward the rotor shaft (12); 11. The multi-stage compressor of claim 1, wherein the inner shroud (14) includes the radially extending fibers and the tangentially extending fibers outside the connection region (14a) to the rotor shaft (12).

12. 12. A multi-stage compressor according to claim 1, characterized in that the inner shroud (14) comprises fibers extending in at least one principal stress direction of the inner shroud (14), in particular fibers (23) extending in a tensile stress direction and / or fibers (24) extending in a compressive stress direction.

13. 13. The multi-stage compressor according to claim 1, wherein each of the impeller blades (16) has a cross section formed in a double T-shape, and a free leg (17) of the double T-shaped impeller blade (16) extends along the inner shroud (14) and the outer shroud (15).

14. 14. A multi-stage compressor according to any one of claims 1 to 13, characterized in that each of the impeller blades (16) comprises a core (20) in at least one central portion (19) connecting the free legs (17) in a transition region from the free legs (17).

15. Use of a multi-stage compressor according to any one of claims 1 to 14 for compressing and / or transporting hydrogen gas, helium gas, natural gas, ammonia, neon or a mixture of at least two of these gases.

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