DE102022111573A1 - Centrifugal compressor - Google Patents

Abstract

The invention relates to a radial compressor (1) with a radial compressor stage (10), the radial compressor stage (10) having an impeller (31), a shaft (32) and a stator (15) having a diffuser (20), and the impeller (31 ) is arranged on the shaft (32) so that it can be driven by it, the impeller (31) has an impeller housing (12), the impeller housing (12) being fluidly connected to the stator (15), the diffuser (20) has a diffuser housing (211) with a diffuser housing cover (23), the diffuser housing (211) being closed on its side opposite the diffuser housing cover (23) with the diffuser blade ring (22), so that between the diffuser housing cover (23) and the diffuser blade ring (22) a diffuser channel (24) is formed. The diffuser blade ring (22) has spaced apart guide vanes (21) connected to the diffuser blade ring (22), which are mounted in a translationally movable manner in the axial direction along the normal vector of the surface of the diffuser blade ring (22). This solves the problem of providing a radial compressor (1) which has an extended surge limit.

Description

The invention relates to a radial compressor with a radial compressor stage, the radial compressor stage having an impeller, a shaft and a stator having a diffuser, and the impeller is arranged on the shaft so that it can be driven by it. The impeller has an impeller housing that is fluidly connected to the stator. The diffuser has a diffuser housing with a diffuser housing cover, the diffuser housing being closed with the diffuser blade ring on its side opposite the diffuser housing cover, so that a diffuser channel is formed between the diffuser housing cover and the diffuser blade ring. The diffuser channel has an entrance region along its circumference, which is arranged on the inner radius of the diffuser blade ring, and an exit region along its circumference, which is arranged on the outer radius of the diffuser blade ring. The diffuser blade ring has guide vanes that are spaced apart from one another and connected to the diffuser blade ring.

Centrifugal compressors compress fluids to a desired pressure. The fluid to be compressed is introduced into the radial compressor and sucked in by an impeller attached to a shaft, where it is set in rotation and deflected in the radial direction. The accelerated fluid then flows through a diffuser in which its kinetic energy is reduced and converted into potential energy in the form of static pressure. The compressed fluid is then removed or, in the case of several radial compressor stages, fed to another radial compressor stage. In multi-stage radial compressors, the impellers of the individual radial compressor stages can be arranged on one shaft or on several shafts.

The EP 1 413 763 B1 describes a bladed diffuser for a centrifugal compressor which has a device for selectively adjusting the pitch of the blades to accommodate variable load conditions. Each of the blades is rotatable about a pivot near its leading edge and engages an actuator near its trailing edge. The actuators are attached to a common ring that can be selectively rotated to move the blades in unison. A throat is formed between adjacent blades and the pivot for each blade is located downstream of the throat on the pressure side of the blade to reduce turbulence in the flow at the throat.

Proceeding from this, the object of the invention is to provide a radial compressor which has an extended surge limit.

This task is solved by the subject matter of patent claim 1. Preferred further training can be found in the subclaims.

According to the invention, a radial compressor is therefore provided with a radial compressor stage, the radial compressor stage having an impeller, a shaft and a stator having a diffuser and the impeller is arranged on the shaft so that it can be driven by it, the impeller has an impeller housing, the impeller housing is fluidly connected to the stator, the diffuser has a diffuser housing with a diffuser housing cover, the diffuser housing being closed on its side opposite the diffuser housing cover with the diffuser blade ring, so that a diffuser channel is formed between the diffuser housing cover and the diffuser blade ring, the diffuser channel having an entrance area along it Circumference, which is arranged on the inner radius of the diffuser blade ring, the diffuser channel has an exit region along its circumference, which is arranged on the outer radius of the diffuser blade ring, and the diffuser blade ring has spaced apart guide vanes connected to the diffuser blade ring, the guide vanes in the axial Direction along the normal vector of the surface of the diffuser blade ring are mounted in a translationally movable manner.

A radial compressor with a radial compressor stage is thus provided, which enables the guide vanes to be moved in and out of the diffuser channel by the translational movement. This option to switch between a non-bladed and a bladed diffuser extends the pumping limit of the centrifugal compressor. The limitations of a bladed diffuser in an overload operating range, which is characterized by high mass flows, are not present in that the area of the diffuser through which the flow passes is not reduced by the guide vanes extended from the diffuser channel. Likewise, the operating range of the radial compressor at small mass flows is expanded by the guide vanes retracted into the diffuser channel in such a way that flow separations begin later and the flow, which is thus guided more advantageously, increases the efficiency of the radial compressor. The surge limit divides the compressor map into a stable and an unstable area. Surging occurs when the operating point of the centrifugal compressor is reduced by a decrease in flow rate or by an increase in flow rate Final pressure gets into the unstable area. The operating behavior of the centrifugal compressor is stored in compressor maps over a wide operating range.

In principle, the contours of the diffuser housing cover and diffuser blade ring can be different from one another. According to a preferred development of the invention, however, it is provided that the diffuser housing cover and the diffuser blade ring run parallel to one another. This embodiment of a diffuser is also known as a parallel-walled diffuser.

It is possible for the diffuser blade ring to be designed with different rows of guide blades. According to a preferred development of the invention, however, the diffuser blade ring has guide blades which are designed in at least two rows, so that at least a second row of guide blades has a larger radius on the diffuser blade ring than a first row of guide blades. This makes it possible to adapt the flow angle to the mass flow and also extend the surge limit to include partial load operation. In addition, it is also possible to provide additional rows of guide vanes on different radii, so that the guide vanes are designed, for example, in three or four rows.

In principle, the guide vanes can be retracted into the diffuser channel in various ways. According to a preferred development of the invention, however, it is provided that the stator has an outlet which is fluidly connected to the output region of the diffuser, the diffuser blade ring has blade chambers on the side facing away from the diffuser channel for receiving the guide blades and the blade chambers are fluidly connected to the outlet in such a way that the fluid can flow following the pressure gradient from a predetermined pressure difference value, so that the guide vanes are extended from the blade chambers in the diffuser blade ring by means of the pressure difference. The exit pressure-related retraction of the guide vanes into the diffuser channel enables the diffuser to be changed from unbladed to bladed operation without additional control. Based solely on the pressure conditions prevailing in the radial compressor, the radial compressor automatically regulates itself towards a more advantageous diffuser configuration that is adapted to the mass flow.

Basically, a guide vane can be stopped in different ways. According to a preferred development of the invention, however, it is provided that the guide blade is stopped in the position retracted into the blade chamber by a guide in such a way that a cavity is formed between the guide blade base and the blade chamber base. This cavity allows the pressurized incoming fluid to flow into the blade chambers, expand, and retract the vanes into the diffuser channel.

It is possible to seal the recessed guide vanes from the diffuser channel in various ways. According to a preferred development of the invention, however, it is provided that the guide vane sunk in the blade chamber is to be sealed with a sealing groove which runs along the edge of the blade chamber, is sealed against the diffuser channel and does not protrude into it. The circumferential sealing groove prevents pressure equalization between the pressure in the blade chambers and the pressure in the diffuser channel. In addition, disruptions to the flow at the transition from the diffuser channel to the blade chambers with the recessed guide blades are avoided.

In principle, with several radial compressor stages, it is possible to fluidly connect different positions along the flow path within the radial compressor to the blade chambers. According to a preferred development of the invention, however, it is provided that in the case of several radial compressor stages, an inlet being arranged in front of the impeller of the first radial compressor stage, the inlet is fluidly connected to the impeller, and in the following radial compressor stages the outlet of the previous radial compressor stage is fluidly connected to the Impeller of the following radial compressor stage up to a penultimate radial compressor stage is connected and the outlet of the last radial compressor stage is fluidly connected to the blade chambers of the diffuser blade rings in such a way that the fluid can flow following the pressure gradient from a predetermined pressure difference value, so that the guide blades from the blade chambers in the diffuser blade ring by means the pressure difference can be extended. The use of the last outlet in several radial compressor stages contributes to the fluid having the required pressure to exceed the predetermined pressure difference value and thus the guide vanes can be extended.

In principle, the fluid can flow to the blade chambers in various ways. According to a preferred development of the invention, however, it is provided that the blade chambers are fluidly connected to the outlet and to the environment by means of a pressure relief valve designed as a T-valve.

In principle, the guide vanes can be movable at the same time. According to a preferred development of the invention, however, it is provided that the blade chambers are provided with pressure relief valves in such a way that individual and/or multiple guide blades are translationally movable at different pressure differences. This makes it possible to generate so-called low-solidity diffuser configurations that achieve advantageous efficiencies in the transition area of the diffuser between partial and overload operation.

Below we will explain the invention in further detail using a preferred exemplary embodiment with reference to the drawings.

• 1 schematisch einen Radialverdichter mit einer Radialverdichterstufe gemäß einem bevorzugten Ausführungsbeispiel der Erfindung,
• 2 schematisch einen Diffusor gemäß einem bevorzugten Ausführungsbeispiel der Erfindung und
• 3 schematisch einen Diffusorschaufelkranz mit einem Laufrad und einer Welle gemäß einem bevorzugten Ausführungsbeispiel der Erfindung.

Show in the drawing

• 1 schematically a radial compressor with a radial compressor stage according to a preferred embodiment of the invention,
• 2 schematically a diffuser according to a preferred embodiment of the invention and
• 3 schematically a diffuser blade ring with an impeller and a shaft according to a preferred embodiment of the invention.

Out of 1 A radial compressor 1 with a radial compressor stage 10 according to a preferred exemplary embodiment of the invention can be seen schematically. In this exemplary embodiment, the radial compressor stage 10 is a first radial compressor stage 10 of a multi-stage radial compressor 1. A fluid flows into an inlet 11 of the radial compressor 1. An impeller 31, which is drivably mounted on a shaft 32, rotates due to the rotation of the shaft 32 in an impeller housing 12 in the radial compressor stage 10. The fluid flows into the radial compressor stage 10 and is sucked in by the rotating impeller 31 and deflected radially.

The impeller housing 12 is fluidly connected to a stator 15. The fluid accelerated in the impeller housing 12 flows into the pinch 13 and is stabilized there by means of the converging walls in order to then flow into a fluid-connected diffuser 20. In the diffuser 20, the speed of the fluid is converted into static pressure and directed into a subsequent 180° deflection 14, which is connected to the diffuser 20. Starting from the 180° deflection 14, the fluid is guided into an outlet 18 through a return blade 16 and a 90° deflection 17.

The part of the stator 15, which includes the 180 ° deflection 14 as well as the return blades 16 and the 90 ° deflection 17, serves to reduce the swirl present in the fluid at the end of the diffuser 20 with as little loss as possible, to increase the static pressure and thereby to enable a swirl-free, homogeneous inflow of the following radial compressor stage 10 via the outlet 18.

The last outlet 18 of the last radial compressor stage 10 of the multi-stage radial compressor 1 has a fluid connection to the diffuser 20, which allows the fluid to flow to the diffuser 20 from a pressure difference value via a pressure relief valve designed as a T-valve. The last radial compressor stage 10, as well as the fluid connection and the pressure relief valve are not shown in the figures.

In 2 the diffuser 20 according to a preferred embodiment of the invention is shown in detail. 2 shows a cross section of the diffuser 20 along the radius of the diffuser 20. A diffuser blade ring 22 of the diffuser 20 has a guide vane arrangement in a tandem configuration. This means that the flow angle of the fluid flowing through a diffuser channel 24 is changed along the radius of the diffuser blade ring 22 by two rows of guide blades 21 arranged one behind the other.

The fluid coming from the pinch 13 flows into a diffuser channel 24 of the diffuser 20. The diffuser channel 24 is closed by a diffuser housing cover 23 arranged parallel to the diffuser blade ring 22. The diffuser housing cover 23 and the diffuser blade ring 22 form the diffuser housing 211. The guide vanes 21 are in 2 retracted into their respective blade chambers 26.

The guide blade 21 is completely integrated into a blade chamber 26. The blade chamber 26 is connected to the diffuser blade ring 22, so that the guide blade 21 can be extended into the diffuser channel 24. The guide vane 21 is stopped in the retracted state by a guide 27 in such a way that a cavity is formed between the guide vane 21 and the blade chamber base. The blade chamber 26 is sealed against the diffuser channel 24 with the guide blade 21 and a double circumferential sealing groove 25, so that a different fluid pressure can prevail in the blade chamber 26. For this purpose, the blade chamber 26 is fluidly connected to the outlet 18 via the above-mentioned T-valve designed as a pressure relief valve.

The fluid flows in 2 through an entrance area 28 of the diffuser channel 24 and leaves the diffuser channel 24 through an exit area 29. In this state, the diffuser is without blades because the guide vanes 21 are sunk into the blade chambers 26. The flow through the diffuser channel 24 of the fluid accelerated in the impeller 32 converts the kinetic energy of the fluid into potential energy in the form of static pressure. The fluid flows through the stator 15 to the outlet 18.

If the radial compressor stage 10 is used with a lower mass flow in partial load operation and the pressure of the fluid in the outlet 18 rises to a set pressure, the T-valve opens and a small part of the fluid flows into the blade chambers 26 following the pressure gradient. The pressure of the incoming fluid in the blade chambers 26 is greater than the pressure in the diffuser channel 24, so that the guide blades 21 move out of the blade chambers 26 and into the diffuser channel 24.

If the radial compressor is dethrottled, the operating point moves towards overload and the speed of the fluid in the stator 15 increases, as a result of which the pressure in the outlet 18 drops to such an extent that the T-valve closes. The blade chambers 26 are fluidly connected to the environment via the third outlet of the T-valve. The fluid pressure in the diffuser channel 24 is at a level above the ambient pressure and the guide vanes 21 move out of the diffuser channel 24 into the blade chambers 26. The fluid from the blade chambers 26 is vented to the environment via the T-valve. The guide vanes 21 are stopped at the guide 27 and are flush with the sealing grooves 25 and the diffuser blade ring 22 towards the diffuser channel 24.

In 3 Finally, a diffuser blade ring 22 as well as an impeller 31 and a shaft 32 according to a preferred exemplary embodiment of the invention can be seen schematically. The fluid accelerated in the impeller 31 flows through the pinch 13 into the entrance area 28 of the diffuser channel 20. The in 3 Diffuser blade ring 22 shown has single row radially arranged guide blades 21, along which the fluid flows in order to leave the diffuser channel 20 at the exit region 29.

Reference symbol list

1

Centrifugal compressor

10

Radial compressor stage

11

entry

12

Impeller housing

13

Pinch

14

180° deflection

15

stator

16

Return blading

17

90° deflection

18

exit

20

diffuser

21

vane

22

Diffuser blade ring

23

Diffuser housing cover

24

Diffuser channel

25

sealing groove

26

Shovel chamber

27

guide

28

Entrance area

29

Exit area

211

Diffuser housing

31

Wheel

32

Wave

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1413763 [0003]

Claims (9)

Radial compressor (1) with a radial compressor stage (10), where the radial compressor stage (10) has an impeller (31), a shaft (32) and a stator (15) having a diffuser (20), and the impeller (31) is arranged on the shaft (32) so that it can be driven by it , the impeller (31) has an impeller housing (12), the impeller housing (12) being fluidly connected to the stator (15), the diffuser (20) has a diffuser housing (211) with a diffuser housing cover (23), the diffuser housing (211) being closed on its side opposite the diffuser housing cover (23) with the diffuser blade ring (22), so that between the diffuser housing cover (23) and a diffuser channel (24) is formed in the diffuser blade ring (22), the diffuser channel (24) having an entrance region (28) along its circumference, which is arranged on the inner radius of the diffuser blade ring (22), the diffuser channel (24) has an exit region (29) along its circumference, which is arranged on the outer radius of the diffuser blade ring (22), and the diffuser blade ring (22) has spaced apart guide vanes (21) connected to the diffuser blade ring (22), the guide blades (21) being mounted in a translationally movable manner in the axial direction along the normal vector of the surface of the diffuser blade ring (22). Radial compressor (1). Claim 1 , whereby the diffuser housing cover (23) and the diffuser blade ring (22) run parallel to one another. Centrifugal compressor (1) according to one of the preceding claims, wherein the guide blades (21) are designed in at least two rows, so that a second row of guide blades (21) has a larger radius on the diffuser blade ring (22) than a first row of guide blades (21). Centrifugal compressor (1) according to one of the preceding claims, wherein the stator (15) has an outlet (18) which is fluidly connected to the output region (29) of the diffuser (20), the diffuser blade ring (22) has blade chambers (26) on the side facing away from the diffuser channel (24) for receiving the guide blades (21) and the blade chambers (26) are fluidly connected to the outlet (18) in such a way that the fluid can flow following the pressure gradient from a predetermined pressure difference value, so that the guide blades (21) are extended from the blade chambers (26) in the diffuser blade ring (22) by means of the pressure difference become. Radial compressor (1) according to the preceding claim, wherein the guide vane (21) is stopped in the retracted position by a guide (27) in such a way that a cavity is formed between the guide vane base and the blade chamber base. Centrifugal compressor (1) according to one of the Claims 4 or 5 , wherein the guide vane (21) recessed in the blade chamber (26) is sealed against the diffuser channel (24) with a sealing groove (25) which runs along the edge of the blade chamber (26) and does not protrude into it. Centrifugal compressor (1) according to one of the Claims 4 until 6 with several radial compressor stages (10), an inlet (11) being arranged in front of the impeller of the first radial compressor stage (10), the inlet (11) being fluidly connected to the impeller, in the following radial compressor stages (10) the outlet (18) the respective previous radial compressor stage (10) is fluidly connected to the impeller of the following radial compressor stage (10) up to a penultimate radial compressor stage (10) and the outlet (18) of the last radial compressor stage (10) is fluidly connected to the blade chambers (26) of the diffuser blade rings is connected that the fluid can flow following the pressure gradient from a predetermined pressure difference value, so that the guide blades (21) can be extended from the blade chambers (26) in the diffuser blade ring (22) by means of the pressure difference. Centrifugal compressor (1) according to one of the Claims 4 until 7 , wherein the blade chambers (26) are fluidly connected to the outlet (18) and to the environment by means of a pressure relief valve designed as a T-valve. Centrifugal compressor (1) according to one of the Claims 4 until 8th , wherein the blade chambers (26) are provided with pressure relief valves in such a way that individual and/or multiple guide blades (21) are translationally movable at different pressure differences.

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