Combined bearing and turbomachine including said bearing

1. A combined bearing for a shaft of a turbomachine, the combined bearing comprising:

at least one radial bearing portion to radially support the shaft

at least one thrust bearing portion to axially support the shaft; and

at least one impeller portion configured to move bearing-fluid in communication with the at least one thrust bearing portion and the at least one radial bearing portion, the at least one impeller portion being rotatable about the shaft.

2. The combined bearing of claim 1 , wherein the at least one thrust bearing portion comprises a first rotary thrust bearing ring and a second rotary thrust bearing ring.

3. The combined bearing of claim 2 , wherein the first rotary thrust bearing ring and the second rotary thrust bearing ring are axially spaced apart from one another and co-acting with opposed stationary thrust pads to support axial loads oriented in opposed axial directions, and wherein the at least one radial bearing portion is arranged between the first rotary thrust bearing ring and the second rotary thrust bearing ring.

4. The combined bearing of claim 3 , wherein a stationary annular pads-carrying member is arranged between the first rotary thrust bearing ring and the second rotary thrust bearing ring.

5. The combined bearing of claim 4 , wherein the stationary annular pads-carrying member supports first thrust bearing pads co-acting with the first rotary thrust bearing ring and second thrust bearing pads co-acting with the second rotary thrust bearing ring, the first thrust bearing pads and the second thrust bearing pads being arranged at axially opposed ends of the stationary annular pads-carrying member.

6. The combined bearing of claim 5 , wherein radial pads are arranged at a substantially cylindrical inner surface of the stationary annular pads-carrying member and co-act with a journal arranged within said substantially cylindrical inner surface.

7. The combined bearing of claim 2 , wherein the at least one impeller portion is integral with one of said first rotary thrust bearing ring and said second rotary thrust bearing ring.

8. The combined bearing of claim 7 , wherein the at least one impeller portion is arranged on a face of said one rotary thrust bearing ring facing opposite the other rotary thrust bearing ring.

9. The combined bearing of claim 1 , wherein an outlet of the at least one impeller portion is in fluid communication with fluid delivery ducts configured and arranged for delivering bearing fluid to the radial bearing portion and the thrust bearing portion.

10. A turbomachine comprising:

a casing;

a shaft supported in the casing for rotation therein;

at least one turbomachine impeller mounted on the shaft for co-rotation therewith; and

a combined bearing according to claim 1 , rotatingly supporting the shaft in the casing.

11. The turbomachine of claim 10 , wherein the shaft has a drive end, for connection to a driver, and a non-drive end, opposite the drive end, and wherein the combined bearing is arranged at one of said drive end and non-drive end of the shaft, and wherein a radial bearing is arranged at the other of said drive-end and non-drive end of the shaft.

12. The turbomachine of claim 11 , wherein a bearing-fluid reservoir is arranged between the combined bearing and the driver, the bearing fluid reservoir being in fluid communication with an inlet of the impeller portion.

13. The turbomachine of claim 11 , wherein the impeller portion is in fluid communication with the radial bearing and is configured to supply pressurized bearing fluid to the radial bearing.

14. The turbomachine of claim 10 , wherein the turbomachine is a centrifugal pump or a subsea pump, and is configured for operating with the shaft in vertical orientation.

15. A method of operating a turbomachine comprising a casing, a shaft supported for rotation in the casing and at least one turbomachine impeller mounted on the shaft for co-rotation therewith the method comprising the following steps:

rotating the shaft against a combined bearing, the combined bearing providing axial and radial support to the shaft, wherein the combined bearing comprises at least one radial bearing portion, at least one thrust bearing portion, and at least one impeller configured to move bearing fluid in communication with the at least one thrust bearing portion and the at least one radial bearing portion; and

delivering pressurized bearing fluid with the at least one impeller to the at least one thrust bearing portion and the at least one radial bearing portion.

16. The combined bearing of claim 1 , wherein the at least one thrust bearing portion comprises at least one rotary thrust bearing ring.