Abstract: A magnetic bearing system (24) supports a shaft (20). The bearing system (24) includes a magnetic rotor (34) and a stator element (36) positioned in proximity to the rotor (34). A plurality of first electromagnets (40, 41, 42) are mounted in the stator element (36). The first electromagnets (40, 41, 42) are of relatively large size to provide high load bearing capacity. A plurality of second electromagnets (44, 45, 46) are mounted in the shator element (36) in spaced relation with the first electromagnets (40, 41, 42), the second electromagnets (44, 45, 46) being of relatively small size to provide high frequency response. Displacement sensors (56, 57, 58) sense position of the shaft (20) relative to the stator element (36). A controller (60) is coupled to the displacement sensors (56, 57, 58) and the electromagnets (40, 41, 42, 44, 45, 46) for controlling current thereto.

Abstract: A sleeve seal heating system for a multi-stage compressor is disclosed. The multi-stage compressor includes a mechanism for dissipating heat disposed between and in fluid communication with a pair of compressor stages in the multi-stage compressor. The present invention contemplates the inclusion of a mechanism for selectively bypassing the heat dissipating mechanism disposed between and in fluid communication with each pair of compressor stages to thereby warm a succeeding stage, causing the stage to become substantially operative. The mechanism for bypassing comprises a bypass valve. The bypass valve is controlled to bypass the mechanism for dissipating heat when a seal in the succeeding stage is not substantially operative. Each compressor stage comprises a piston reciprocating within a piston chamber, the piston chamber being in valved communication with and between a fluid input and a fluid output.