US 5,244,183 AGranted

Fugitive emission sealing assembly

AssigneeKeystone International Holdings Corp.

InventorsDouglas G. Calvin, Edward G. Holtgraver

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Abstract

A sealing assembly, usable with a valve or the like, having a movable shaft within a main housing and controlling a product under a first pressure. A cartridge housing forms a continuation of the main housing. An extension of the shaft extends through the cartridge housing and forms an annulus therewith. Spaced first and second annular seals movably seal the annulus between the shaft extension and the cartridge housing, forming a central sealing chamber. An injector introduces sealing medium into the central sealing chamber under a pressure higher than the product pressure. An accumulator receives excess sealing medium from the central sealing chamber, and can also be associated with monitoring means. Additional annular seals may form additional chambers spaced along the shaft, and these chambers may likewise be used for injection of sealing media and/or monitoring and/or leak detection.

Claims39

Dependent claims

A sealing cartridge removably attachable to a housing having a process pressure zone containing a product under a first pressure, said housing having a through aperture surrounding a movable shaft, said sealing cartridge comprising:

(a) a cartridge body having first and second ends with first and second openings, respectively, said cartridge body being removably attached to said housing, with said first opening coaxially aligned with said aperture, and forming a static fluid-tight seal with said housing;
(b) a shaft extension within said cartridge body and exiting said cartridge body second end through said second opening;
(c) spaced first and second annular seals each having an inner diameter slidably sealing said shaft extension and an outer diameter sealing said cartridge body to form a sealing pressure zone between said first and second seals, while permitting relative movement between the shaft extension and the cartridge body, the first and second seals being adapted to be activated by pressure in said sealing zone;
(d) means for selectively introducing a fluid sealing medium into said sealing pressure zone at a second pressure higher than said first pressure and adapted to prevent back flow from the sealing pressure zone;
(e) an accumulator comprising an accumulator housing connected to the cartridge body and defining an accumulator chamber communicating with the sealing pressure zone, the accumulator further comprising a member movable to expand and contract the accumulator chamber and adapted to provide an indication of its position, the movable member being resiliently biased to resist expansion;
whereby:
when there is adequate sealing pressure in the sealing zone, the movable member will overcome its resilient bias to expand the accumulator chamber, and the resilient bias will act to maintain the pressure in the sealing zone;
and when the pressure in the sealing zone drops, the resilient bias will move the movable member to contract the accumulator chamber, and the position so indicated will alert an operator to the need for corrective measures.

5 more elements

A shaft seal assembly, comprising:

(a) main housing means defining a process pressure zone for containing a fluid product under a first pressure and a central sealing chamber longitudinally spaced from said first pressure zone;
(b) a shaft movably mounted in said main housing means and extending from said process pressure zone into and through said central sealing chamber;
(c) a primary annular seal sealing between said shaft and said main housing means for preventing leakage from said process pressure zone toward said central sealing chamber;
(d) at least one annular secondary seal having an inner diameter slidably sealing against said shaft and an outer diameter sealing against said main housing means distal said process pressure zone, whereby said central sealing chamber defines a sealing pressure zone between said primary and secondary seals;
(e) an injector for introducing sealing medium into said sealing pressure zone, at a second pressure higher than said first pressure, comprising an injector housing connected to the main housing means and defining an injector chamber communicable with the sealing pressure zone, but closed from pressure communication with the outside of the injector housing and with said process pressure zone, and containing a quantity of such sealing medium, means for selectively reducing the volume of the injector chamber to force sealing medium into the sealing pressure zone, and a check valve permitting fluid flow from the injector chamber into the sealing pressure zone but preventing back flow from the sealing pressure zone into the injector chamber;
and
(f) an accumulator comprising an accumulator housing defining an accumulator chamber communicatively connected to the sealing pressure zone, the accumulator further comprising a member movable to expand and contract the accumulator chamber and adapted to provide an indication of its position, the movable member being resiliently biased to resist expansion;
whereby:
when there is adequate sealing pressure in the sealing zone, the movable member will overcome its resilient bias to expand the accumulator chamber, and the resilient bias will act to maintain the pressure in the sealing zone;
and when the pressure in the sealing zone drops, the resilient bias will move the movable member to contract the accumulator chamber, and the position so indicated will alert an operator to the need for corrective measures.

7 more elements

A shaft seal assembly comprising:

(a) main housing means defining a process pressure zone for containing a fluid product under a first pressure and a central sealing chamber longitudinally spaced from said process pressure zone;
(b) a shaft movably mounted in said main housing means and extending from said process pressure zone into and through said central sealing chamber;
(c) a first annular seal sealing between said shaft and said main housing means for preventing leakage from said process pressure zone toward said central sealing chamber;
(d) a second annular seal having an inner diameter sealing against said shaft and an outer diameter sealing against said main housing means distal said process pressure zone,
(e) a third annular seal having an inner diameter sealing against said shaft and an outer diameter sealing against said main housing means, and disposed between said first and second seals whereby a sealing pressure zone is defined between said second and third seals, and one auxiliary pressure zone is defined between said first and third seals;
(f) an injector for introducing sealing medium into said sealing pressure zone at a second pressure higher than said first pressure and higher than that outside the injector housing, comprising an injector housing connected to the main housing means and defining an injector chamber communicable with the second pressure zone but closed from communication with the outside of the injector housing and containing a quantity of such sealing medium, means for selectively reducing the volume of the injector chamber to force sealing medium into the second pressure zone, and a check valve permitting fluid flow from the injector chamber into the sealing pressure zone but preventing back flow from the sealing pressure zone into the injector chamber;
(g) an accumulator comprising an accumulator housing defining an accumulator chamber communicatively connected to the sealing pressure zone the accumulator further comprising a member movable to expand and contract the accumulator chamber and adapted to provide an indication of its position, the movable member being resiliently biased to resist expansion;
whereby:
when there is adequate sealing pressure in the sealing zone, the movable member will overcome its resilient bias to expand the accumulator chamber, and the resilient bias will act to maintain the pressure in the sealing zone;
and when the pressure in the sealing zone drops, the resilient bias will move the movable member to contract the accumulator chamber, and the position so indicated will alert an operator to the need for corrective measures;
(h) another such injector associated with said auxiliary pressure zone, the injectors being independently operable;
and
(i) another such accumulator associated with the auxiliary pressure zone, the accumulators being independent of each other.

10 more elements

A system for on-line emission reduction comprising at least one valve assembly having a valve housing defining a process pressure zone.

a housing extension communicatively adjoining the valve housing and extending away from the valve housing toward an actuator,
a valve shaft disposed partially in the valve housing and extending through the housing extension,
a first annular seal in the valve housing sealing between the valve housing and the valve shaft,
a second annular seal in the housing extension spaced from the first seal and having an inner diameter sealing against the valve shaft and an outer diameter sealing against the housing extension,
a third annular seal in the housing extension spaced from the second seal and on the opposite side of the second seal from the first seal,
whereby a sealing pressure zone is defined between the second and third seals, and an auxiliary pressure zone is defined between the first and second seals;
an injector with a self-contained quantity of sealing fluid communicatably connected with one of said sealing or auxiliary pressure zones, and having means for selectively injecting the sealing fluid into the one pressure zone at a pressure higher than that in the process pressure zone, and adapted to prevent back flow from the seal at the outer end of the one pressure zone being energized by virtue of pressure in the one zone;
an accumulator comprising an accumulator housing defining an accumulator chamber communicatively connected with the one pressure zone, the accumulator further comprising a member movable to expand and contract the accumulator chamber and adapted to provide an indication of its position, the movable member being resiliently biased to resist expansion;
whereby:
when there is adequate sealing pressure in the one zone, the movable member will overcome its resilient bias to expand the accumulator chamber, and the resilient bias will act to maintain the pressure in the one zone;
and
when the pressure in the one zone drops, the resilient bias will move the movable member to contract the accumulator chamber, and the position so indicated will alert an operator to the need for corrective measures;
and leak detection means for detecting leakage from said process pressure zone.

10 more elements

Dependencies are inferred from the claim text.