Centrifugal compressor

Abstract

A centrifugal compressor for compressing a fluid in a gas phase or a supercritical phase includes: a rotational shaft; an axial flow path extending along an axial direction of the centrifugal compressor; a radial flow path communicating with the axial flow path and extending along a radial direction of the centrifugal compressor on a downstream side of the axial flow path; an impeller at least partially disposed in the radial flow path and configured to rotate together with the rotational shaft to increase pressure of the fluid flowing in the radial flow path; and a pre-compression unit disposed in the axial flow path at a position distant from a leading edge of the impeller on an upstream side of the leading edge and configured to increase the pressure of the fluid in advance before the fluid is introduced to the leading edge.

1 . A centrifugal compressor for compressing a fluid in a gas phase or a supercritical phase, the centrifugal compressor comprising:
 a rotational shaft;   an axial flow path extending along an axial direction of the centrifugal compressor;   a radial flow path communicating with the axial flow path and extending along a radial direction of the centrifugal compressor on a downstream side of the axial flow path;   an impeller at least partially disposed in the radial flow path and configured to rotate together with the rotational shaft to increase pressure of the fluid flowing in the radial flow path; and   a pre-compression unit disposed in the axial flow path at a position distant from a leading edge of the impeller on an upstream side of the leading edge and configured to increase the pressure of the fluid in advance before the fluid is introduced to the leading edge,   the centrifugal compressor being a multi-stage compressor including at least one section including a plurality of the impellers arranged on multiple stages along a flow direction of the fluid, and   the pre-compression unit being disposed in the axial flow path on an upstream side of a first-stage impeller in each of the at least one section, at a position distant from a leading edge of the first-stage impeller on an upstream side of the first-stage impeller.   
     
     
         2 . (canceled) 
     
     
         3 . The centrifugal compressor according to  claim 1 , wherein the pre-compression unit is configured to rotate together with the rotational shaft to increase the pressure of the fluid. 
     
     
         4 . The centrifugal compressor according to  claim 1 , wherein the pre-compression unit includes a spiral blade disposed on an outer circumference side of the rotational shaft and extending along the axial direction spirally around the rotational shaft. 
     
     
         5 . The centrifugal compressor according to  claim 4 , wherein the pre-compression unit further includes a shroud disposed on an outer circumference side of the spiral blade so as to cover the spiral blade. 
     
     
         6 . The centrifugal compressor according to  claim 5 , further comprising a sealing member disposed between an outer circumference surface of the shroud and a wall surface of a casing of the centrifugal compressor, the wall surface facing the outer circumference surface. 
     
     
         7 . The centrifugal compressor according to  claim 5 , wherein the impeller is formed separately from the spiral blade and the shroud.