Centrifugal Compressor, and Method for Manufacturing Same

A centrifugal compressor, comprising:

• a rotation shaft;
• a plurality of centrifugal impellers mounted on the rotation shaft;
• a diffuser causing fluid exiting one of the centrifugal impellers to flow in a centrifugal direction from the rotation shaft;
• and
• a return channel that is provided downstream of the diffuser and causes the fluid flowing from the diffuser to the centrifugal impeller of a subsequent stage to flow in a return direction toward the rotation shaft, wherein
• the return channel is provided between a hub-side wall surface and a shroud-side wall surface,
• the return channel includes a front set of vanes arranged in a circular array on an upstream side and a rear set of vanes arranged in a circular array on a downstream side,
• the front set of vanes and the rear set of vanes are both formed on one of the hub-side wall surface or the shroud-side wall surface,
• one of the front set of vanes or the rear set of vanes is formed on an annular member that is formed separately from the other one of the front set of vanes or the rear set of vanes,
• the other one of the front set of vanes or the rear set of vanes is formed by direct processing for the wall surface of the return channel, and joined to the other one of the hub-side wall surface or the shroud-side wall surface by welding;
• and
• the annular member is fitted to the return channel.

A method for manufacturing a centrifugal compressor, comprising:

• a formation step of forming one of a front set of vanes or a rear set of vanes on an annular member formed separately from the other one of the front set of vanes or the rear set of vanes, the front set of vanes being arranged in a circular array on an upstream side in a return channel provided between a hub-side wall surface and a shroud-side wall surface, the rear set of vanes being arranged in a circular array on a downstream side;
• a joining step of joining the other one of the front set of vanes or the rear set of vanes, which is formed on one of the hub-side wall surface or the shroud-side wall surface by direct processing for the wall surface of the return channel, to the other one of the hub-side wall surface or the shroud-side wall surface by welding;
• and
• a fitting step of after the joining step, fitting the annular member to the return channel.