Shaft bearing for a turbomachine, turbomachine, and method of operating a turbomachine

Abstract

The shaft bearing supports the rotor of a turbo-machine which extends along a rotor axis. The shaft bearing has a bearing element with a bearing surface. The bearing surface supports an associated rotor surface and the bearing element can be axially displaced. The invention further relates to a turbo-machine and to a method for operating said turbo-machine.

We claim:  
     
         1 . A turbomachine, comprising: 
 a casing with a conical inner wall;    a rotor extending through said casing along a rotor center line through said casing, said rotor carrying a plurality of rotor blades each having a blade tip facing towards said inner wall and having a conicity substantially corresponding to said inner wall, whereby a radial gap is formed between each said blade tip and said inner wall;    a shaft bearing having at least one axially displaceable bearing element formed with a bearing surface immediately adjacent a rotor surface and being capable of axially displacing said rotor surface; and    a mechanical displacement device connected to said bearing element and configured to displace said bearing element and said rotor, and to compensate for an increase in said radial gap upon heating during an operation of the turbomachine.    
     
     
         2 . The turbomachine according to  claim 1 , wherein said axially displaceable bearing element is an axially displaceable annular piston.  
     
     
         3 . The turbomachine according to  claim 1 , wherein said mechanical displacement device comprises a displacement element and a displacement drive.  
     
     
         4 . The turbomachine according to  claim 3 , wherein said displacement drive includes an electric motor.  
     
     
         5 . The turbomachine according to  claim 1 , wherein said bearing surfaces are displaceably disposed for displacement by between 0.5 mm and 5 mm.  
     
     
         6 . The turbomachine according to  claim 1 , wherein said bearing is a rotor bearing for stationary operation.  
     
     
         7 . The turbomachine according to  claim 1 , wherein said rotor blades are disposed in at least two rows of rotor blades at an axial distance from one another, and wherein said casing and said blade tips are configured such that an axial displacement of said rotor provides an equal radial gap for each of said rows.  
     
     
         8 . A method of operating a turbomachine, which comprises: 
 providing a turbomachine with a casing having a conical inner wall and a rotor in the casing, the rotor carrying a plurality of rotor blades each having a blade tip facing towards the inner wall and having a conicity substantially corresponding to a conicity of the inner wall and forming a radial gap between each blade tip and the inner wall;    supporting the rotor in a shaft bearing having at least one axially displaceable bearing element formed with a bearing surface immediately adjacent a rotor surface; and    displacing the rotor relative to the casing by displacing the axially displaceable bearing element, and thereby adjusting the radial gap between the blade tip and the inner wall to suit a given operating condition of the turbomachine.    
     
     
         9 . The method according to  claim 8 , which comprises setting the radial gap on reaching a powered operation condition of the turbomachine.  
     
     
         10 . The method according to  claim 9 , which comprises determining that the powered operation condition of the turbomachine has been achieved during a specified time period.  
     
     
         11 . The method according to  claim 9 , which comprises determining that the powered operation condition of the turbomachine has been achieved by determining the axial gap occurring as a consequence of thermal expansions.  
     
     
         12 . The method according to  claim 9 , which comprises determining that the powered operation condition of the turbomachine has been achieved by determining a relative displacement between the casing and the rotor.