Rotary kinetic fluid motors or pumps – Bearing – seal – or liner between runner portion and static part
Reexamination Certificate
1995-02-14
2001-04-03
Kwon, John T. (Department: 3747)
Rotary kinetic fluid motors or pumps
Bearing, seal, or liner between runner portion and static part
C415S174500, C277S408000
Reexamination Certificate
active
06210107
ABSTRACT:
SUMMARY OF THE INVENTION
This invention relates to barrier seal systems which are suitable for sealing a rotating shaft extending through a bore in a housing. The housing may be part of a pump, compressor or similar equipment containing a high pressure fluid. The seal system includes inboard and outboard mechanical end face seals, each having primary and mating rings. The space between the inboard and outboard seals defines a buffer chamber. A buffer fluid is supplied to the buffer chamber. The inboard seal pumps buffer fluid across the seal faces toward the high pressure side of the seal. Seals of this general nature are disclosed in Sedy, U.S. Pat. No. 4,290,611.
One of the objects of the present invention is a barrier seal system of the type described which reduces or eliminates the requirement for buffer fluid pressure, minimizes potential emissions and simplifies the buffer fluid supply equipment.
Another object of the invention is a barrier seal system in which the inboard seal is double balanced so that the inboard seal will function in the event of pressure reversals.
Another object of the invention is a barrier seal system which is operable in high pressure applications. Barrier seal systems according to the present invention which are intended for use in high pressure environments have hard primary and mating rings to resist deflection. High pressure seals also have optimum face and dam widths to maximize the pressure developed by the inboard seal.
A further object of the invention is a barrier seal system which is pressurized on the outside diameter of the inboard seal faces, thereby utilizing centrifugal force to prevent fouling of the seal faces and secondary seal.
Yet another object of the invention is a barrier seal system of the type described which includes a buffer fluid containment element forming a containment chamber on the high pressure side of the inboard seal faces. The containment chamber prevents the process fluid from contacting secondary seals or the primary and secondary ring seal faces.
Other objects may appear from time to time in the following specification, drawings and claims.
The above objects are realized by a seal system having a gland plate connected to the housing of the equipment to be sealed. A sleeve is mounted on the shaft for rotation therewith. A first static seal in the form of an O-ring is placed between the sleeve and shaft to prevent leakage along the shaft. An outboard mechanical end face seal has a mating ring connected to the gland plate and a seal head connected to the sleeve for rotation with the shaft. The seal head includes a retainer and a plurality of springs disposed between the retainer and primary ring, urging the primary ring into contact with the mating ring. A secondary seal is located between the retainer and the primary ring.
The barrier seal further includes an inboard mechanical end face seal, at least a portion of which is mounted in the annular space between the housing and the rotating shaft. The inboard seal has a primary ring and a retainer fixed to the gland plate. The retainer at least partially encloses the primary ring to fix its radial position while allowing axial movement of the primary ring. A secondary seal is disposed between the retainer and the primary ring. A mating ring of the inboard seal surrounds the sleeve and is connected thereto for rotation with the shaft. A static seal is placed between the sleeve and the mating ring to prevent leakage between them.
The mating and primary rings of the inboard seal have opposed, relatively rotating, radial seal faces on one side thereof. The outer diameters of the seal faces are exposed to the pressure of the process fluid.
The inboard seal is positioned axially of the outboard seal to define a buffer chamber. The mating ring of the inboard seal has grooves formed therein which extend from the buffer chamber partially across the mating ring seal face to a non-grooved dam portion. The grooves pump buffer fluid across the seal faces into the high pressure side of the inboard seal.
The primary ring of the inboard seal is arranged to be double balanced so that pressure reversals can be tolerated without loss of closing force. The buffer fluid may be gravity fed to the buffer chamber from a reservoir. A buffer fluid containment element spanning the inboard primary and secondary rings and in contact therewith defines a containment chamber which prevents process fluid from contacting the seal faces or the secondary seal of the inboard seal.
REFERENCES:
patent: 2824759 (1958-02-01), Tracy
patent: 3489419 (1970-01-01), Stratienko
patent: 3746350 (1973-07-01), Mayer et al.
patent: 4212475 (1980-07-01), Sedy
patent: 4290611 (1981-09-01), Sedy
patent: 4434986 (1984-03-01), Warner
patent: 4466619 (1984-08-01), Adams
patent: 4721311 (1988-01-01), Kakabaker
patent: 4722534 (1988-02-01), Wentworth
patent: 4889348 (1989-12-01), Amundson et al.
patent: 4889350 (1989-12-01), Tranter
patent: 3012711 (1980-10-01), None
patent: 2950444 (1981-06-01), None
patent: 8908798 (1989-09-01), None
“Mechanical Seals”, E. Mayer, 2nd Edition, 1972, ILIFFE Books, London GB, pp. 176-179.
Hosanna Richard
Netzel James P.
Volden Douglas J.
John Crane Inc.
Kwon John T.
McEachran, Jambor, Keating, Bock & Kurtz
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