Self-contained instrument and seal air system for a centrifugal compressor

摘要

A self-contained seal air and instrument air system for a compressor includes a pneumatically controllable inlet valve and a pneumatically controllable valve means for depressurizing the compressor. An electronic controller directs compressor operation. A receiver tank is provided which includes an inlet through which compressed air enters and an outlet port. A means is provided for separating the compressed air flowing from the receiver into a first path which provides a first source of seal air to seals of a rotating shaft of the compressor, and a second path which provides instrument air. A means is provided for separating the compressed air flowing in the instrument air path into a first path which provides actuating air to the inlet valve and the valve means for depressurizing the compressor, and a second path which provides a source of signal air. First and second current-to-pressure converters are flow connected in the signal air path and are disposed in electronic signal receiving relation to the electronic controller. A second source of seal air is provided from a tap port disposed at a predetermined location on the compressor discharge.