# US 11,306,734 B2 · Centrifugal compressor

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- Number: US 11,306,734 B2
- Document ID: US11306734B2
- Status: Granted
- Kind: B2
- Application number: 16/970,840
- Filed: 2019-02-20
- Published: 2021-04-22
- Granted: 2022-04-19
- Earliest claimed: 2018-02-20
- Assignees: Mitsubishi Heavy Industries Thermal Systems, Ltd.
- Applicants: Mitsubishi Heavy Industries Thermal Systems, Ltd.
- Inventors: Jun Koga; Jyun Miyamoto
- Web page: https://patentgrep.com/patent/US11306734B2

## CPC

- F04D 29/44: Fluid-guiding means, e.g. diffusers
- F04D 29/444: {Bladed diffusers}
- F04D 17/12: Multi-stage pumps
- F04D 17/122: {the individual rotor discs being, one for each stage, on a common shaft and axially spaced, e.g. conventional centrifugal multi- stage compressors}
- F04D 29/682: {by fluid extraction}
- F05D 2250/70: Shape
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

A centrifugal compressor includes a rotary shaft; a hollow casing; a first-stage inlet guide vane; a first-stage impeller; a diffuser; a return flow channel; return vanes; a second-stage inlet guide vane; and a second-stage impeller. The return vanes are arranged at predetermined intervals in a circumferential direction of the rotary shaft and a vane angle of each return vane is changed in a region from a leading edge, at which the fluid is introduced, to a predetermined position and the vane angle is maintained constant in a region from the predetermined position to a trailing edge, at which the fluid is discharged, in terms of meridian plane distance in a direction from the leading edge to the trailing edge.

## Claims

### Claim 1

A centrifugal compressor comprising:
a rotary shaft;
a hollow casing that rotatably supports the rotary shaft and is provided with an intake port on one side in an axial direction of the rotary shaft and a discharge port on the other side;
a first-stage inlet guide vane that is disposed in the intake port;
a first-stage impeller that is disposed downstream of the first-stage inlet guide vane in the casing;
a diffuser that is disposed downstream of the first-stage impeller in the casing;
a return flow channel at which a fluid that flows from an inner side in a radial direction of the rotary shaft to an outer side in the radial direction after flowing through the diffuser is reversed to the inner side in the radial direction;
return vanes that are disposed in the return flow channel;
a second-stage inlet guide vane that is disposed downstream of the return vanes in the casing; and
a second-stage impeller that is disposed downstream of the second-stage inlet guide vane in the casing,
wherein the return vanes are arranged at predetermined intervals in a circumferential direction of the rotary shaft and a vane angle of each return vane is changed from a leading edge, at which the fluid is introduced, to a predetermined position and the vane angle is maintained constant from the predetermined position to a trailing edge, at which the fluid is discharged, in terms of meridian plane distance in a direction from the leading edge to the trailing edge, and
wherein the predetermined position is set 50% to 70% from the leading edge.

### Claim 2 (depends on 1)

The centrifugal compressor according to claim 1,
wherein the vane angle from the predetermined position to the trailing edge is set to an angle along the radial direction of the rotary shaft.

### Claim 3 (depends on 1)

The centrifugal compressor according to claim 1,
wherein a fluid channel area at the trailing edge of the return vanes are set to be larger than a fluid channel area at the leading edge of the return vanes.

### Claim 4 (depends on 1)

The centrifugal compressor according to claim 1,
wherein a length of the second-stage inlet guide vane in the radial direction of the rotary shaft is set to be smaller than a length of the return vanes in the radial direction of the rotary shaft.

### Claim 5 (depends on 1)

The centrifugal compressor according to claim 1,
wherein the trailing edge of the return vanes and a leading edge of the second-stage inlet guide vane are disposed to be offset from each other in the circumferential direction of the rotary shaft.