Multistage compressor

Abstract

A multi-stage compressor (10), namely a multi-stage radial compressor or a multi-stage diagonal compressor, with a compressor rotor, wherein the compressor rotor has a rotor shaft (12) and several impellers (11) attached to the rotor shaft (12), axially directed into the airflow and radially or diagonally directed outwards, wherein each impeller (11) has a curved inner cover plate (14), a curved outer cover plate (15) and several curved impeller blades (16) arranged between the inner cover plate (14) and the outer cover plate (15), wherein the inner cover plate (14), the outer cover plate (15) and the impeller blades (16) are each made of a fiber composite material, and wherein the rotor shaft (12) extends through a recess (13) in the inner cover plate (14) of the respective impeller (11). Fig. 1

Description

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

[0002] Thermal turbomachinery is generally divided into compressors on the one hand and steam and gas turbines on the other. Turbomachinery is also referred to as a turbomachine. Compressors are generally classified as axial compressors, radial compressors, and diagonal compressors. Furthermore, axial, radial, and diagonal compressors are further subdivided into single-stage and multi-stage compressors. The present invention relates to multi-stage compressors, specifically either multi-stage radial compressors or multi-stage diagonal compressors.

[0003] For the compression of light gases, such as hydrogen or helium, compressors must be operated at high peripheral speeds to enable efficient compression. Existing multi-stage radial or diagonal compressors with metallic construction are only partially suitable for the high peripheral speeds required for compressing light gases.

[0004] DE 11 2011 100 312 T5 discloses an impeller of a radial compressor, which is manufactured as a composite material impeller using a resin transfer molding (RTM) process. The impeller is formed from a fiber composite material, specifically from fibers embedded in resin.

[0005] EP 2 504 581 B1 discloses an impeller for a turbomachine with multiple blades. The inner walls of the blades are connected to a material element comprising fiber structures woven in a pattern.

[0006] There is a need for a novel multi-stage compressor, designed as a radial or diagonal compressor, that can be operated at high peripheral speeds and is therefore suitable for compressing light gases. Based on this need, the present invention aims to provide a novel multi-stage compressor, designed as a radial or diagonal compressor. This objective is achieved by a multi-stage compressor according to claim 1. According to the invention, each impeller has a curved inner cover plate, a curved outer cover plate, and several curved impeller blades arranged between the inner and outer cover plates. The inner cover plate, the outer cover plate, and the impeller blades are each made of a fiber-reinforced composite material, and the rotor shaft extends through a recess in the inner cover plate of the respective impeller.The inner cover plate can also be called the hub plate, and the outer cover plate can also be called the cover plate. The curved impeller blades can be twisted three-dimensionally.

[0007] The present invention proposes for the first time a multi-stage compressor, designed as a radial or diagonal compressor, whose impellers have a curved inner cover plate, a curved outer cover plate, and several curved, in particular three-dimensionally twisted, impeller blades arranged between the curved inner and outer cover plates, all of which are made of a fiber-reinforced composite material. The rotor shaft extends through a recess in the inner cover plate of the respective impeller. Such multi-stage compressors can be operated at high peripheral speeds. These compressors are therefore particularly suitable for the compression of hydrogen gas or other light gases, such as helium gas, natural gas, ammonia, neon, or mixtures of at least two such gases.

[0008] The impeller blades, the inner cover plate and the outer cover plate can be integral components of the respective impeller designed in integral construction.

[0009] Preferably, the impeller blades, the inner cover plate, and the outer cover plate are separate components of the respective impeller designed in differential construction, wherein the impeller blades are connected to the inner and outer cover plates at least by a material-bonded or chemically bonded connection. Optionally, the impeller blades can additionally be connected to the inner and outer cover plates by mechanical connecting elements. For the ease of manufacturing the multi-stage compressor according to the invention, it is advantageous that the impeller blades, the inner cover plate, and the outer cover plate of the respective impeller are each designed as separate components that are connected at least by a material-bonded or chemically bonded connection.Such differentially designed impellers can be operated at high circumferential speeds and are easier to manufacture compared to integrally designed impellers.

[0010] Preferably, each impeller is connected to the rotor shaft at least via a friction-fit connection. Optionally, each impeller can also be connected to the rotor shaft via a material-fit, chemical-fit, and / or positive-fit connection. This provides a particularly advantageous connection between the respective impeller and the rotor shaft, thus enabling a multi-stage compressor that can be operated at high peripheral speeds.

[0011] Preferably, the fiber-reinforced composite material of the inner cover plate in the connection area to the rotor shaft comprises high-stiffness fibers, while the fiber-reinforced composite material of the inner cover plate outside the connection area to the rotor shaft, as well as the fiber-reinforced composite material of the outer cover plate and the impeller blades, comprises high-strength fibers. Thus, each impeller comprises different types of fibers, namely, high-stiffness fibers on the one hand and high-strength fibers on the other. The high-stiffness fibers are used in the area of ​​the inner cover plate of the respective impeller, specifically in those sections of the inner cover plate that serve as the connection to the rotor shaft. In other sections of the inner cover plate, as well as in the area of ​​the outer cover plate and the impeller blades, the fiber-reinforced composite material preferably comprises high-strength fibers. Ultimately, the impellers can be securely attached to the rotor shaft of the multi-stage compressor to ensure high circumferential speeds.Furthermore, any combination of the fiber types mentioned is possible in the areas mentioned above and especially in transitions between the areas mentioned.

[0012] Preferably, the inner cover plate has fibers extending axially and tangentially in the connection area to the rotor shaft, and fibers extending radially and tangentially outside the connection area to the rotor shaft. Alternatively or additionally, the inner cover plate has fibers extending in at least one principal stress direction, in particular fibers extending in a tensile stress direction and / or fibers extending in a compressive stress direction. Such fiber orientation enables the impellers to withstand high loads, ultimately allowing the respective multi-stage compressor to be operated at high circumferential speeds.

[0013] Preferred embodiments of the invention are set forth in the dependent claims and the following description.

[0014] Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1: A partial sectional view of a multi-stage compressor according to the invention in the area of ​​an impeller; Fig. 2: A perspective view of an impeller of a multi-stage compressor according to the invention; Fig. 3: An exploded view of the impeller of the Fig. 2 ; Fig. 4 a wheel blade of the wheel of the Fig. 2 ; Fig. 5 a detail, namely a fiber orientation, of an inner cover plate of the impeller of the Fig. 2 ; Fig. 6 shows a further detail, namely a fiber orientation and the course of principal stress directions, of an inner cover plate of the impeller of the Fig. 2 ; Fig. 7 a further detail, namely a sectional view, of an inner cover plate of the impeller of the Fig. 2 with fiber layers; Fig. 8 a detail, namely a profile, of an impeller blade of the impeller of the Fig. 2 .

[0015] Fig. 1 Figure 1 shows a partial sectional view of a multi-stage compressor 10 according to the invention in the area of ​​an impeller 11 of the compressor 10, which is arranged on a rotor shaft 12. Viewed in the axial direction A, several such impellers 11 are arranged one behind the other on the outer circumference of the rotor shaft 12.

[0016] The rotor shaft 12 together with the impellers 11 forms a compressor rotor which is rotatably mounted in a compressor housing (not shown) of the multi-stage compressor 10 according to the invention.

[0017] The compressor 10 according to the invention is a multi-stage radial compressor or a multi-stage diagonal compressor. The impellers 11 are thus exposed to a gas flow in the axial direction A, and the outflow direction extends radially R or diagonally to the same.

[0018] The respective impeller 11 of the multi-stage compressor 10 has a curved or domed inner cover plate 14, a curved or domed outer cover plate 15 and several curved or domed impeller blades 16 arranged between the inner cover plate 14 and the outer cover plate 15.

[0019] The inner cover plate 14, the outer cover plate 15 and the impeller blades 16 of the respective impeller 11 each consist of a fiber composite material, wherein the rotor shaft 12 extends through a recess 13 in the inner cover plate 14 of the respective impeller 11.

[0020] The inner cover plate 14 can also be called a hub plate, and the outer cover plate 15 can also be called a cover plate. The curved or arched impeller blades 16 are twisted three-dimensionally.

[0021] As already explained above, the respective impeller 11 and thus its impeller blades 16 are subjected to an axial flow direction A and are subjected to an outflow direction in the radial direction R or diagonal direction.

[0022] The impeller blades 16, the inner cover plate 14 and the outer cover plate 15, each made of a fiber composite material, can be integral components of a respective impeller 11 designed in integral construction.

[0023] However, in order to enable the simple manufacture of the respective impeller 11, it is preferred if the inner cover plate 14, the outer cover plate 15 and the impeller blades 16 are each designed as separate components of an impeller 11 designed in differential construction, wherein the impeller blades 16 are then connected on the one hand to the inner cover plate 14 and on the other hand to the outer cover plate 15 at least via a material-bonded or material-bonded connection.

[0024] In a differential design, the impeller blades 16 are connected to the inner cover plate 14 and the outer cover plate 15 at least by means of an adhesive bond, and optionally the impeller blades 16 are additionally connected to the inner cover plate 14 and the outer cover plate 15 by means of mechanical connecting elements, such as bolts, rivets or screws.

[0025] The material-bonded connection of the impeller blades 16 to the inner cover plate 14 and the outer cover plate 15 can also be achieved by welding in the case of thermoplastics. However, bonding is preferred.

[0026] Fig. 4 Figure 1 shows a single impeller blade 16, which is designed as a double-T-shaped impeller blade 16 in cross-section. Free legs 17 of the impeller blade 16 are connected to the inner cover plate 14 and the outer cover plate 15 as described above, at least by bonding and preferably also by mechanical connecting elements.

[0027] The bonding of the respective impeller blade 16 in the area of ​​its free legs 17 to the inner cover plate 14 and the outer cover plate 15 is preferably carried out over the entire surface in the area of ​​the respective free legs 17.

[0028] In addition, mechanical connecting elements can extend through the free legs 17 as well as through the inner cover plate 14 and outer cover plate 15 for additional connection, which in particular counteract a so-called peeling of the cover plates 14, 15 under operating loads and increase the load-bearing capacity of the impeller 11.

[0029] The impeller blades 16 can be of integral or differential design. In the Fig. 4 In the illustrated embodiment, the impeller blade 16, which has a double-T cross-section, is designed in a differential configuration and is formed from two U-shaped profiles 18 arranged back-to-back. The free legs 17 of the U-shaped profiles extend away from the central sections 19 connecting the free legs 17, which form the backs of the U-shaped profiles 18. The central sections 19 of the U-shaped profiles 18 are connected, at least by bonding, and optionally also by mechanical fasteners such as bolts, rivets, or screws.

[0030] Although the provision of double-T-shaped impeller blades 16 via back-to-back U-shaped profiles 18 is preferred, it is also possible to provide a double-T-shaped impeller blade 16 having a single central section 19 from which the free legs 17 extend, as shown in Fig. 4 shown, extend away. Fig. 8 Figure 1 shows a section of a double-T-shaped impeller blade 16 with a single central part 19, wherein inserts or cores 20 made of plastic, fiber composite material, foam or the like may be arranged in transition areas between the central part 19 and the free legs 17.

[0031] As already explained, the rotor shaft 12 extends through a recess 13 in the respective impeller 11 of the multi-stage compressor 10. The respective impeller 11 sits on the rotor shaft 12 with its impeller seat, which is formed by the inner cover plate 14.

[0032] The rotor shaft 12 is preferably made of a metallic material, but it can also be made of a fiber-reinforced composite material. In particular, if the rotor shaft 12 is made of a metallic material, for example a steel material, the impellers 11 are connected to the rotor shaft 12 at least by a frictional connection, preferably an interference fit.

[0033] To form such a press fit connection, the rotor shaft 12 can be cooled from a metallic material and, in the cooled state, inserted into the recesses 13 of the impellers 11, so that after heating the rotor shaft 12, the press fit connection between the rotor shaft 12 and the impellers 11 is formed.

[0034] In addition to the force-fit connection, each impeller 11 can also be connected to the rotor shaft 12 via a material-fit connection such as an adhesive connection and / or a form-fit connection such as a profile connection or a dowel pin connection.

[0035] As previously stated, the inner cover plate 14, the outer cover plate 15, and the impeller blades 16 are made of a fiber-reinforced composite material. In the connection area to the rotor shaft 12, i.e., in a section 14a extending in the axial direction A, which defines the recess 13 of the respective impeller 11 for the passage of the rotor shaft 12, the fiber-reinforced composite material of the inner cover plate 14 preferably comprises high-strength carbide fibers. In other sections 14b extending in the radial direction R, the fiber-reinforced composite material of the inner cover plate 14 preferably comprises high-strength HT fibers. The fiber-reinforced composite material of the outer cover plate 15 and the impeller blades 16 also preferably comprises high-strength HT fibers. Combinations of different fiber types can also be used in the aforementioned areas or sections.

[0036] Fig. 5 und 6 The figures show possible fiber orientations in the area of ​​the inner cover plate 14, specifically in the area of ​​that section 14b of the inner cover plate 14 which extends outside the connection area 14a to the rotor shaft 12 in the radial direction R. According to Fig. 5 Outside the connection area 14a of the inner cover plate 14, fibers 21 extend radially in the direction R, while other fibers 22 extend tangentially or circumferentially. In the area of ​​section 14a, i.e., in the connection area of ​​the inner cover plate 14 to the rotor shaft 12, fibers 21 extend axially and fibers 22 extend tangentially or circumferentially. This is in Fig. 5 und 6 not shown.

[0037] According to Fig. 6 Outside the connection area 14a of the inner cover plate 14, fibers extend in at least one principal stress direction of the radially extending sections 14b of the inner cover plate 14, namely at least one fiber 23 in the tensile direction and at least one fiber 24 in the compressive direction of the inner cover plate 14 outside the connection area 14a thereof to the rotor shaft 12.

[0038] Although in Fig. 6 While only one fiber 23 extending in the direction of tension and one fiber 24 extending in the direction of compression are shown, of course several such fibers 23, 24 extending in the principal stress directions can be present over the circumference.

[0039] The fiber guidance of the Fig. 5 can be used with the fiber guidance of the Fig. 6 They can be combined, namely in several layers or strata of fibers arranged on top of each other.

[0040] Fig. 7 shows a cross-section through an inner cover plate 14 in the axial cutting direction, wherein Fig. 7 It can be seen that the inner cover plate 14 has several layers of fibers 21, 22 in sections 14a, 14b.

[0041] Thus, in the exemplary embodiment of the Fig. 7In the area of ​​the connection section 14a of the inner cover plate 14 to the rotor shaft 12, an innermost layer of fibers 22 extending in the tangential or circumferential direction is formed. A layer of fibers 21 extending in the axial direction A is laid on top of this, with these fibers 21 extending in the radial direction R in section 14b and, in the illustrated embodiment, forming the innermost fiber layer of section 14b. On top of this layer of fibers 21 extending axially in the area of ​​section 14a and radially in the area of ​​section 14b, two layers of fibers 22 extending in the tangential or circumferential direction are positioned, with a core 25 made of, for example, plastic, fiber-reinforced composite, foam, or the like being positioned between these two layers of fibers 22 in the transition area between section 14a and section 14b.The outermost layer of fibers 21 is formed in the area of ​​section 14a of the inner cover plate 14 and in the area of ​​section 14b of the inner cover plate 14, which extend in section 14a in the axial direction A of the inner cover plate 14 and thus of the impeller 11, and in section 14b in the radial direction R of the inner cover plate 14 and thus of the impeller 11.

[0042] The outer cover plate 15 can also be made of a fiber composite material and may have fibers extending in the axial and / or radial direction and / or tangential direction or circumferential direction.

[0043] The multi-stage compressor 10 according to the invention enables high peripheral speeds. Therefore, the multi-stage compressor 10 is particularly suitable for compressing light gases such as hydrogen, helium, natural gas, ammonia, neon, or mixtures of such gases. Consequently, the multi-stage compressor 10 according to the invention is preferably used for compressing and / or transporting such gases or gas mixtures.

[0044] Resins, such as epoxy resins, or thermoplastics, such as PEEK, can be used as the matrix material of the respective fiber-reinforced composite. The fibers are preferably carbon fibers. Reference symbol list

[0045] 10 Compressor 11 Impeller 12 Rotor shaft 13 Recess 14 Inner cover plate 15 Outer cover plate 16 Impeller blade 17 Leg 18 U-shaped profile 19 Center section 20 Core 21 Fiber 22 Fiber 23 Fiber 24 Fiber 25 Core Axial direction Radial direction

Claims

1. Multi-stage compressor (10), namely multi-stage radial compressor or multi-stage diagonal compressor, with a compressor rotor, wherein the compressor rotor has a rotor shaft (12) and several impellers (11) attached to the rotor shaft (12), axially directed and radially or diagonally directed, characterized by the fact that Each impeller (11) has a curved inner cover plate (14), a curved outer cover plate (15) and several curved impeller blades (16) arranged between the inner cover plate (14) and the outer cover plate (15), wherein the inner cover plate (14), the outer cover plate (15) and the impeller blades (16) are each made of a fiber composite material, and wherein the rotor shaft (12) extends through a recess (13) in the inner cover plate (14) of the respective impeller (11).

2. Multi-stage compressor (10) according to claim 1, characterized by the fact thatthe impeller blades (16), the inner cover plate (14) and the outer cover plate (15) are integral components of the respective impeller (11) designed in integral construction.

3. Multi-stage compressor (10) according to claim 1, characterized by the fact that the impeller blades (16), the inner cover plate (14) and the outer cover plate (15) are separate components of the respective differentially designed impeller (11), which are preferably connected at least by a material-bonded connection.

4. Multi-stage compressor (10) according to claim 3, characterized by the fact that the impeller blades (16) are connected to the inner cover plate (14) and the outer cover plate (15) at least by an adhesive connection.

5. Multi-stage compressor (10) according to claim 4, characterized by the fact that the impeller blades (16) are additionally connected to the inner cover plate (14) and the outer cover plate (15) via mechanical connecting elements, in particular via bolts, rivets or screws.

6. Multi-stage compressor (10) according to one of claims 1 to 5, characterized by the fact that the rotor shaft (12), which is made of a metallic material or a fiber composite material, and each impeller (11) are connected at least by a force-fit connection.

7. Multi-stage compressor (10) according to claim 6, characterized by the fact that the rotor shaft (12) and each impeller (11) are connected via a press fit connection.

8. Multi-stage compressor (10) according to claim 6 or 7, characterized by the fact that the rotor shaft (13) and each impeller (11) are additionally connected via a material-locking connection and / or a form-locking connection.

9. Multi-stage compressor (10) according to one of claims 1 to 8, characterized by the fact thatthe fiber composite material of the inner cover plate (14) in the connection area (14a) to the rotor shaft (12) comprises high-stiffness fibers, and that the fiber composite material of the inner cover plate (14) outside the connection area (14a) to the rotor shaft (12) as well as the fiber composite material of the outer cover plate (15) and the impeller blades (16) comprises high-strength fibers.

10. Multi-stage compressor (10) according to claim 9, characterized by the fact that the fiber composite material of the inner cover plate (14) in the connection area (14a) to the rotor shaft (12) additionally comprises high-strength fibers, and / or the fiber composite material of the inner cover plate (14) outside the connection area (14a) to the rotor shaft (12) as well as the fiber composite material of the outer cover plate (15) and the impeller blades (16) additionally comprises high-stiffness fibers.

11. Multi-stage compressor according to one of claims 1 to 10, characterized by the fact thatthe inner cover plate (14) in the connection area (14a) of the same to the rotor shaft (12) has fibers extending in the axial direction and fibers extending in the tangential direction, and the inner cover plate (14) outside the connection area (14a) to the rotor shaft (12) has fibers extending in the radial direction and fibers extending in the tangential direction.

12. Multi-stage compressor (10) according to one of claims 1 to 11, characterized by the fact that the inner cover plate (14) has fibers extending in at least one principal stress direction of the inner cover plate (14), in particular fibers extending in a tensile stress direction (23) and / or fibers extending in a compressive stress direction (24).

13. Multi-stage compressor (10) according to one of claims 1 to 12, characterized by the fact thatEach impeller blade (16) has a double-T-shaped cross-section, with free legs (17) of the double-T-shaped impeller blades (16) extending along the inner cover plate (14) and the outer cover plate (15).

14. Multi-stage compressor (10) according to one of claims 1 to 13, characterized by the fact that Each impeller blade (16) has a core (20) in at least one central part (19) connecting the legs (17) in transition areas from the free legs (17).

15. Use of a multi-stage compressor (10) according to any one of claims 1 to 14 for the compression and / or transport of hydrogen gas, helium gas, natural gas, ammonia, neon or a mixture of at least two of these gases.

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