US 5,980,218 A · Multi-stage compressor having first and second passages for cooling a motor during load and non-load operation

Abstract

A multi-stage compressor having at least two compressor stages comprises an inter-cooler provided between the stages for cooling a gas being discharged from a compressor in the preceding stage. The compressor stages are driven by a common electric motor, of which a rotating shaft is supported by magnetic bearings. A part of the gas cooled by the inter-cooler and a part of the work gas discharged from a bleed valve provided down-stream of a rear stage of the compressor are selectively introduced into the electric motor or the magnetic bearings. Thus, at the time of load operation the gas discharged from the inter-cooler is introduced into the motor or the magnetic bearings to cool them, and at the time of non-load operation the gas discharged from the bleed valve is introduced into the motor or the magnetic bearings to cool them. It is possible to ensure a flow rate of gas required for cooling the motor during non-load operation with economy during load operation.

Claims17

Dependent claims

A multi-stage compressor adapted to be switched between load operation and non-load operation, comprising:

a high-speed electric motor having a rotating shaft;
a first and a second compressor stage including impellers mounted on both ends of said rotating shalt;
and inter-cooler mounted between said first and second compression stages;
a suction throttle valve provided on a suction side of the compressor;
a bleed valve provided on a discharge side of the compressor;
and a first and a second branch passage wherein said first branch passage branches from a downstream side of said impeller disposed at said second stage and wherein said second branch passage is branched from a downstream side of said inter-cooler;
said first and second branch passages connect with each other to form a confluent passage, and said confluent passage connects to form a cooling flow passage for permitting a cooling gas to pass through said high-speed electric motor.

4 more elements

Dependencies are inferred from the claim text.

Multi-stage compressor having first and second passages for cooling a motor during load and non-load operation

Life of this patent

Multi-stage compressor having first and second passages for cooling a motor during load and non-load operation

Life of this patent

Abstract

Claims17