Centrifugal compressor and diffuser for centrifugal compressor

A multi-stage centrifugal compressor comprising a rotation shaft, a plurality of impellers mounted on said rotation shaft, and a first vaned diffuser provided radially outwardly of at least one stage of said impellers and having two opposed wall surfaces and a plurality of first vanes disposed between said wall surfaces in a spaced relationship with one another in a circumferential direction;

• Characterized in that a second vaned diffuser is provided at a downstream side of said first vaned diffuser, said second vaned diffuser having two opposed wall surfaces and a plurality of second vanes disposed between said wall surfaces in a spaced relationship with one another in the circumferential direction, and an axial distance between said two opposed wall surfaces of said second vaned diffuser being decreased progressively from an inlet to an outlet.

A centrifugal compressor comprising a rotation shaft, an impeller mounted on said rotation shaft, and a vaned diffuser provided radially outwardly of said impeller and having two opposed wall surfaces and a plurality of vanes disposed between said wall surfaces in a spaced relationship with one another in a circumferential direction;

• Characterized in that a vaneless diffuser is provided at a downstream side of said vaned diffuser, said vaneless diffuser having two opposed wall surfaces between which axial distance is smoothly decreased progressively from an inlet to an outlet.

A diffuser comprising a vaned diffuser portion provided on an outer periphery of an impeller, and a vaneless diffuser portion provided around an outer periphery of said vaned diffuser, said vaned diffuser portion having two opposed wall surfaces and a plurality of vanes disposed between said wall surfaces in a spaced relationship with one another in a circumferential direction, and said vaneless diffuser having two opposed wall surfaces;

• Characterized in that in a meridian cross-section, the distance between said two wall surfaces, forming said vaneless diffuser, is decreased progressively from an inner end to an outer end.