Centrifugal compressor with air extraction and return at the casing

Abstract

A centrifugal compressor includes a rotor 2 , which is rotatably borne in a casing 1 . A fluid gap flow between the casing 1 and the rotor 2 is extracted via cutouts in the casing 1.

1 . A centrifugal compressor, comprising:
 a casing;   a rotor rotatably borne in the casing;   a fluid gap flow between the casing and the rotor; and   at least one extraction port in the casing for extracting fluid from the fluid gap flow.   
   
   
       2 . The centrifugal compressor of  claim 1  and further comprising at least one injection port in the casing for injecting fluid into an axial flow before a tip of the rotor. 
   
   
       3 . The centrifugal compressor of  claim 2 , wherein extraction and injection of the fluid flow are coupled. 
   
   
       4 . The centrifugal compressor of  claim 3 , and further comprising at least one line connecting the extraction port with the injection port. 
   
   
       5 . The centrifugal compressor of  claim 4 , wherein the extraction port is positioned alongside the rotor in a flow direction. 
   
   
       6 . The centrifugal compressor of  claim 4 , wherein the extraction port is positioned downstream of the rotor in a flow direction. 
   
   
       7 . The centrifugal compressor of  claim 6 , wherein at least one of the extraction port and the injection port is in a form of at least one circumferential slot in the casing. 
   
   
       8 . The centrifugal compressor of  claim 6 , wherein at least one of the extraction port and the injection port is in a form of at least one discrete cutout in the casing. 
   
   
       9 . The centrifugal compressor of  claim 8 , wherein the centrifugal compressor is stator-less. 
   
   
       10 . The centrifugal compressor of  claim 4 , and further comprising at least one heat exchanger to cool the fluid flow between extraction and injection. 
   
   
       11 . The centrifugal compressor of  claim 10 , wherein the heat exchanger is positioned in an area of a bypass duct. 
   
   
       12 . The centrifugal compressor of  claim 11 , and further comprising a controllable shutoff element positioned in the line. 
   
   
       13 . The centrifugal compressor of  claim 12 , and further comprising a throttle in the line. 
   
   
       14 . The centrifugal compressor of  claim 2 , wherein the injection port injects the fluid flow at a shallow angle to a smooth wall of the casing. 
   
   
       15 . The centrifugal compressor of  claim 2 , wherein the casing has a stepped portion in a wall thereof and the injection port injects the fluid flow into the stepped portion. 
   
   
       16 . The centrifugal compressor of  claim 1 , wherein the extraction port is positioned alongside the rotor in a flow direction. 
   
   
       17 . The centrifugal compressor of  claim 1 , wherein the extraction port is positioned downstream of the rotor in a flow direction. 
   
   
       18 . A centrifugal compressor, comprising:
 a casing;   a rotor rotatably borne in the casing; and   at least one injection port in the casing for injecting fluid into an axial flow before a tip of the rotor.   
   
   
       19 . The centrifugal compressor of  claim 18 , wherein the injection port injects the fluid flow at a shallow angle to a smooth wall of the casing. 
   
   
       20 . The centrifugal compressor of  claim 18 , wherein the casing has a stepped portion in a wall thereof and the injection port injects the fluid flow into the stepped portion.