Centrifugal compressor

A centrifugal compressor, comprising:

• an impeller fixed on an outer periphery of a rotary shaft;
• a diffuser disposed at a radially outer side of the impeller;
• a casing accommodating the impeller and the diffuser;
• a scroll flow passage connected to an outlet of the diffuser, the scroll flow passage being formed into a scroll shape by a scroll inner peripheral wall and a scroll outer peripheral wall positioned at a radially outer side of the scroll inner peripheral wall;
• and
• a discharge pipe connected to the casing so as to form a discharge flow passage for guiding a fluid from the scroll flow passage to outside of the casing,
• wherein the scroll inner peripheral wall is positioned at an inner side, in a radial direction, of the outlet of the diffuser,
• wherein the discharge pipe comprises an inner wall surface that has a radially inner region continuing to the scroll inner peripheral wall,
• wherein a connection position of the radially inner region to the casing is positioned on a same side of a first line segment that passes a center of the rotary shaft and that is parallel to a center axis of an outlet portion of the discharge pipe as a scroll termination portion of the scroll flow passage when viewed in an axial direction of the rotary shaft, and
• wherein the radially inner region comprises a protruding portion that protrudes toward an inner side of the discharge flow passage in at least a partial region between an inlet portion of the discharge pipe and the outlet portion.