Fluid intensifier for a dry gas seal system

Patent metadata

Field	Value
Publication number	US-9719521-B2
Application number	US-201313920346-A
Country	US
Kind code	B2
Filing date	Jun 18, 2013
Priority date	Jun 18, 2012
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

A gas supply system for a mechanical seal turns on the gas supply at a pressurized flow rate at the time of compressor case pressurization and remains on during compressor rotation until pressure is adequate. The gas supply system has an intensifier that includes a pair of mechanically inter-connected pneumatic pressure cylinders which comprise a drive cylinder that affects movement of a boost cylinder wherein the displacement of these mechanically interconnected pistons in the drive cylinder and boost cylinder intensifies the pressure being discharged by the boost cylinder and supplied as a barrier fluid to the mechanical seal. The intensifier uses a control valve and operating system which includes a fast-acting 5/2-way solenoid valve having a feedback loop connected to a control system which includes a microprocessor that controls valve actuation.

First claim

We claim:

1. An intensifier for a mechanical seal gas supply system comprising:
a drive cylinder which is operatively connected to a boost cylinder by an intermediate piston rod, said drive cylinder having a pressurized cylinder housing which defines a drive pressure chamber subdivided into variable-volume, first and second cylinder chambers by a reciprocating drive piston;
said boost cylinder having a pressurized cylinder housing which defines a boost pressure chamber that is subdivided into variable-volume, third and fourth cylinder chambers by a reciprocating boost piston, a piston rod slidably extending between said drive and boost pistons so that said boost piston is driven by said drive piston, a gas flow valve system being provided to ensure a continuous, pressurized flow of barrier gas during the reciprocating movement of said boost cylinder by said drive cylinder, said gas flow valve system including a gas inlet that receives a pressurized dry gas at a supply gas pressure as the barrier fluid from a gas supply, said gas inlet including supply lines that alternatingly feed said dry gas to said third cylinder chamber and said fourth cylinder chamber wherein said valve system alternatingly controls the feed of said pressurized dry gas to said third and fourth cylinder chambers wherein said dry gas is pressurized by said boost piston to an increased gas pressure, said gas flow valve system also including a gas outlet that discharges said dry gas after increased pressurization by said boost piston as a mechanical seal barrier fluid;
said first and second chambers being alternately pressurized and depressurized by an air source of pressurized air to drive said drive piston through opposite first and second drive strokes in opposite first and second directions and effect a corresponding driving of said boost cylinder, a diametric area of each of said drive and boost pistons differing wherein the area of the drive piston is larger than the area of said boost piston such that air pressure driving the drive cylinder increases an outlet pressure of said pressurized dry gas generated in the boost cylinder and being output from said boost cylinder to said increased gas pressure for supplying a mechanical seal with a continuous pressurized flow of said dry gas as the barrier fluid at said increased gas pressure; and
a control valve system to control a flow of said dry gas through said boost cylinder, which comprises a 5/2 way control valve unit having a control valve, said control valve having five ports comprising an inlet port which connects to said air source of said pressurized air that is separate from said gas supply, first and second outlet ports to alternatingly supply said pressurized air to said first and second cylinder chambers and first and second exhaust ports to alternatingly depressurize and exhaust air from said first and second cylinder chambers, said control valve system including an automated, computer-driven controller which selectively opens and closes said ports of said control valve and controls operation of said intensifier in response to operation of said drive cylinder and a position of said drive piston, said control valve including a high speed, fast-acting solenoid valve which is suitable for non-lubricated dry air applications and is actuated by said controller, said solenoid valve comprising a solenoid control having a valve spool which is selectively operated in response to operation of said drive cylinder to move between two operative positions and a solenoid which is actuated by said controller upon detection of the position of said drive piston to drive the valve spool from an initial first operative position to a second operative position, said solenoid control having a return spring wherein the solenoid is actuated by said controller to drive the valve spool from said initial first operative position to said second operative position, and when said solenoid is deactivated by said controller, said return spring biasing said valve spool to the initial first operative position, so that said valve spool switches between the first and second operative positions to reciprocate said drive piston through said first and second drive strokes and reciprocate said boost piston to supply said continuous pressurized flow of said dry gas as a barrier fluid;
said first and second drive strokes being defined by opposite said first and second stroke ends, and said control system including at least a first feedback sensor at said first stroke end which communicates with said controller and serves as a proximity sensor which detects the position of said drive piston as said drive piston approaches said first feedback sensor located at said first stroke end to control said solenoid control, and said feedback sensor detecting the proximity of said drive piston at said first stroke end and said controller reversing the movement of said drive piston upon detecting said drive piston moving through said second piston stroke, said controller being programmed to selectively control and operate said drive piston by reversing the cycle of said drive piston as the drive piston travels through said first drive stroke based upon one of detecting the proximity of said drive piston at said second stroke end by a second feedback sensor or timing a set period of time during which said piston stroke moves through said first piston stroke, the controller automatically reversing said drive piston at said second stroke end after detection by said second proximity sensor or after said set period of time, and then at said first stroke end detected by said first proximity sensor, the controller again reversing the stroke based upon the proximity sensor signal.

2. The intensifier according to claim 1 , wherein said control valve defines multiple flow paths wherein, when said valve spool is in said first operative position, a first flow path is connected between said inlet port and the first outlet port which is connected to the first cylinder chamber which supplies the pressurized drive air to the first cylinder chamber and drives the drive piston through said first drive stroke in the first direction, said control valve also defining a second flow path which is connected with the second outlet port and connected with the first exhaust port to exhaust the second cylinder chamber when the first cylinder chamber is pressurized by air from said inlet port with said second exhaust port being blocked.

3. The intensifier according to claim 2 , wherein, when said valve spool is in said second operative position, a third flow path is connected between said inlet port and the second outlet port which is connected to the second cylinder chamber which supplies the pressurized drive air to the second cylinder chamber and drives the drive piston through said second drive stroke in the second direction, said control valve also defining a fourth flow path which is connected with the first outlet port and connected with the second exhaust port to exhaust the first cylinder chamber when the second cylinder chamber is pressurized by air from said inlet port with said first exhaust port being blocked.

4. The intensifier according to claim 3 , wherein said controller signals said control valve to switch said valve spool to the second operative position as said drive piston reaches an end limit of said first drive stroke in said first direction, which then reverses the operation of the drive piston and causes said drive piston to reverse stroke and move through said second drive stroke in said second direction.

5. The intensifier according to claim 4 , wherein when said valve spool is in said first operative position, said first flow path is connected between said inlet port and said first outlet port which is connected to said first cylinder chamber to supply the pressuriz

Assignees

• Sears John
• Bakalchuk Vladimir
• Figueroa Luis
• Flowserve Man Co

Inventors

• Sears John
• Bakalchuk Vladimir
• Figueroa Luis

Classifications

• F16J15/00

  Sealings · CPC title

• F15B3/00 Primary

  Intensifiers or fluid-pressure converters, e.g. pressure exchangers; Conveying pressure from one fluid system to another, without contact between the fluids {(fluid-driven pumps F04B9/08)} · CPC title

• F04D29/10 Primary

  Shaft sealings · CPC title