Compressor rotor structure and method for arranging said rotor structure

A method for arranging a rotor structure of a compressor,

• wherein the rotor structure comprises a tie bolt and two rotor shafts respectively affixed to respective ends of the tie bolt, and a plurality of impeller bodies supported by the tie bolt, the plurality of impeller bodies mechanically coupled to one another along a rotor axis by way of a plurality of hirth couplings,
• wherein the method comprises:
• arranging a first impeller body of the plurality of impeller bodies to provide a first stage of compression,
• arranging each subsequent impeller body to provide a subsequent stage of compression,
• wherein each respective impeller body defines a respective Di/D2 ratio,
• wherein the Di/D2 ratio of at least one of the impeller bodies is different than the Di/D2 ratio for the remaining impeller bodies,
• wherein, based on the different Di/D2 ratio, respective surfaces defined by an inlet of said at least one of the impeller bodies is located at a different distance relative to the rotor axis compared to location of surfaces defined by respective inlets of the remaining impeller bodies,
• wherein Di is indicative of a respective inner diameter of a flow path into an inlet of a respective impeller body, and
• wherein D2 is indicative of respective outer diameter of the respective impeller body.