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

• US 5,443,369 A
• Filed: 06/09/1993
• Issued: 08/22/1995
• Est. Priority Date: 06/09/1993
• Status: Expired due to Fees

• Current Assignee: Ingersoll-Rand Company (Trane Technologies plc)
• Original Assignee: Ingersoll-Rand Company (Trane Technologies plc)
• Inventors: Biehler, Devin D., Martin, Daniel T.
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): KORYTNYK, PETER G
• Application Number:
  US08/074,078
• Time in Patent Office: 804 Days
• Field of Search: 417/364, 417/299, 417/302, 417/308, 417/244, 417/253, 417/53, 417/313, 137/115, 137/116, 137/487.5, 95/117, 96/108, 96/118
• US Class Current: 417/53
• CPC Class Codes: F04D 29/102 especially adapted for elastic fluid pumps

Abstract

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.

Claims

1. A self-contained seal air and instrument air system comprising:

a compressor having an inlet, a discharge, and at least one rotating shaft which has disposed thereon at least one set of seals;

engine means for providing a motive force to the compressor;

a controllable inlet valve flow connected with the compressor inlet;

electronic controller means for directing compressor operation;

a receiver tank having an inlet through which compressed air enters and an outlet port;

means for filtering the compressed air flowing from the receiver tank outlet port;

means for separating the compressed air flowing from the receiver tank into a first path which provides a first source of seal air to the seals of the rotating shaft of the compressor, and a second path which provides instrument air;

controllable valve for depressurizing the compressed air system;

means for filtering and drying the compressed air entering the instrument air path;

means for separating the compressed air flowing in the instrument air path into a first path which provides actuating air to the controllable inlet valve and the controllable depressurizing valve, and a second path which provides a source of signal air;

pressure regulator means flow connected with the actuator air path;

filter regulator means for filtering the air entering the signal air path and for regulating the pressure in the signal air path to a predetermined pressure;

first and second current-to-pressure converter means flow connected in the signal air path and disposed in electronic signal receiving relation to the electronic controller, and wherein the first current-to-pressure converter is disposed in pneumatic signal transmitting relation to the controllable inlet valve and the second current-to-pressure converter is disposed in pneumatic signal transmitting relation to the controllable depressurizing valve;

pressure regulator means flow connected with the seal air path; and

a second source of seal air provided from a tap port disposed at a predetermined location on the compressor discharge.

2. A self-contained seal air and instrument air system comprising;

a multi-stage centrifugal compressor having an inlet, a discharge, and a main rotating shaft which has disposed thereon at least one set of seals, the centrifugal compressor being operable in a loaded and an unloaded condition;

diesel engine means for providing a motive force to the centrifugal compressor;

an inlet valve flow connected with the compressor inlet;

pneumatic means for controlling operation of the inlet valve;

electronic controller means for directing compressor operation;

a receiver tank having an inlet through which compressed air enters and an outlet port which is disposed in a substantially higher location than the location of the inlet;

means for filtering compressed air flowing from the receiver tank through the outlet port;

means for separating the compressed air flowing from the receiver tank into a first path which provides a first source of seal air to the seals of the rotating shaft of the compressor, and a second path which provides instrument air;

valve means for depressurizing the compressed air system;

pneumatic means for controlling operation of the depressurizing valve means;

means for filtering and drying the compressed air entering the instrument air path;

means for separating the compressed air flowing in the instrument air path into a first path which provides actuating air to the means for controlling operation of the inlet valve and the means for controlling operation of the depressurizing valve means, and a second path which provides a source of signal air;

pressure regulator means flow connected with the actuator air path;

filter regulator means for filtering the air entering the signal air path and for regulating the pressure in the signal air path to a predetermined pressure;

first and second current-to-pressure converter means flow connected in the signal air path and disposed in signal receiving relation to the electronic controller which is operable to supply the first and second current-to-pressure converter means with a predetermined current signal, and wherein the first current-to-pressure converter is disposed in pneumatic signal transmitting relation to the pneumatic means for controlling operation of the inlet valve, and the second current-to-pressure converter is disposed in pneumatic signal transmitting relation to the pneumatic means for controlling operation of the depressurizing valve means, the first and second current-to-pressure converters providing a pneumatic signal which is linear with respect to the current signal;

pressure regulator means flow connected with the seal air path; and

a second source of seal air provided from a tap port which is flow connected at the first stage outlet of the compressor, and wherein during compressor operation, if the receiver tank pressure is equal to or greater than the pressure at the tap port, the receiver tank will supply seal air to the seal air branch, and if the receiver tank pressure is less then tap port pressure, the compressed air from the tap port will supply the seal air.

3. A self-contained seal air and instrument air system, as claimed in claim 2, which further includes a normally closed pressure switch which is disposed in electronic communication with the electronic controller, and which is mounted in pressure sensing relation with the seal air path pressure regulator means, the pressure switch providing automatic shutdown of the compressor when the pressure of the compressed air flowing from the pressure regulator is less than a predetermined value.

4. In a compressed air system having a centrifugal compressor which includes at least one stage, a compressor inlet, a compressor discharge, and a main rotating shaft which has disposed thereon at least one set of seals, the centrifugal compressor being operable in a loaded and an unloaded condition, a method of providing seal air to the compressor shaft seals, the method comprising:

storing compressed air in a receiver tank having an inlet through which the compressed air enters and an outlet port through which the compressed air may pass at a predetermined time;

filtering the compressed air flowing from the receiver tank through the outlet port;

transmitting, as a first source of seal air to the seals of the rotating shaft of the compressor, the compressed air flowing from the outlet port of the receiver tank to a pressure regulating means;

regulating the first source of seal air to a predetermined pressure;

bleeding compressed air from a first stage of the centrifugal compressor;

transmitting, as a second source of seal air to the seals of the rotating shaft of the compressor, the compressed air flowing from the first stage of the centrifugal compressor to the pressure regulating means; and

regulating the second source of seal air to a predetermined pressure, and during compressor operation, if the receiver tank pressure is equal to or greater than the pressure at the first stage of the centrifugal compressor, transmitting the first source of seal air to the seals of the rotating shaft of the compressor, and if the receiver tank pressure is less than the pressure at the first compressor stage transmitting the second source of seal air to the seals of the rotating shaft of the compressor.