Fluid handling – With leakage or drip collecting
Reexamination Certificate
2000-10-25
2002-06-11
Walton, George L. (Department: 3753)
Fluid handling
With leakage or drip collecting
C137S240000, C137S580000, C285S013000, C285S121300, C285S121600
Reexamination Certificate
active
06401746
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
This invention relates generally to rotating unions for transferring material streams between stationary and rotating material-carrying equipment. More specifically, the invention concerns rotating unions for handling bearing damaging fluids and semi-fluids, gaseous fluids having poor heat dissipation characteristics, environmentally sensitive compositions, and other materials wherein internal material leakage is an important concern.
A rotating union is used to transfer a material stream between a material provider and a material recipient that must rotate relative to each other. Typically, the material provider, such as an inlet conduit leading from a material source, is stationary while the material recipient, such as an outlet conduit leading to fluid processing equipment, rotates relative to the material provider. In other implementations, the material provider rotates relative to a stationary material recipient.
In either case, material to be transferred is directed through a material stream passage formed in a first rotating union member, across a dynamically sealed material transfer interface, to a material stream passage formed in a second rotating union member that is rotatably coupled to the first rotating union member via a bearing system. Dynamic sealing is provided by a dynamic seal assembly that mounts to the first and second rotating union members. The seal assembly has dynamic seal faces that are spring-biased into mutual rotational engagement to contain the transferred material as it passes between the first and second rotating union members.
Some rotating union applications call for the transfer of bearing damaging (e.g., abrasive) fluids and semi-fluids, gaseous fluids having poor heat dissipation characteristics, environmentally sensitive compositions, and other materials into or out of processing equipment. Such materials include, by way of example only, paint (having a ratio of 70% or more solids to 30% or less solvents), glue (hot and cold), rubber, and any of a variety of plastics or other polymers, such as sealants.
In certain rotating unions of the prior art, the handling of such materials has been problematic. For example, when bearing damaging material has been transferred, it has tended to leak past the dynamic seal and contact the bearings, ultimately degrading or damaging them. This condition is believed to be attributable to a variety of factors, including (1) misalignment of the dynamic seal faces causing them to intermittently separate during rotation, (2) unequal spring loading on the dynamic seal faces so as to aggravate the effects of seal misalignment, and (3) the selection of dynamic seal face materials that lack sufficient hardness. In addition, none of the rotating unions of the prior art, as far as known, have sought to affirmatively remove heat when transferring gaseous fluids having poor heat dissipation characteristics. There are also no known rotating unions that remove leakage material from the vicinity of the bearings once it does leak past the dynamic seal. One prior art approach has utilized drainage holes to remove leakage material; however, this is a passive approach to material removal, and does not affirmatively work to prevent the material from contacting the bearings.
It is with overcoming the foregoing deficiencies of the prior art that the present invention is concerned.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved rotating union for use with bearing damaging fluids and semi-fluids, gaseous fluids having poor heat dissipation characteristics, environmentally sensitive compositions, and other materials, that greatly reduces the likelihood that material will leak past the dynamic seal faces and into the bearing area of the rotating union. A further object of the invention is to provide an improved rotating union that employs a system for affirmatively removing material that does leak past the dynamic seal faces and into the vicinity of the bearings.
To that end, a rotating union is provided that comprises two separate circulating systems. One circulating system is a primary system for transferring a material stream through the union from a material provider to a material recipient arranged for mutual relative rotation. The other circulating system is a secondary system for circulating a barrier fluid past the dynamic seal(s) of the union and carrying leakage material from the primary system away from the dynamic seal(s).
In a first preferred embodiment, the rotating union of the invention includes a generally cylindrical body and a generally annular sleeve that is radially spaced from the body and rotatably coupled thereto via a pair of axially-spaced bearings. The body and the sleeve are formed with ports and interconnecting passages for transferring a material stream therethrough and these ports and passages communicate with each other via a material transfer interface that is dynamically sealed by a dynamic seal assembly. A very finely lapped (preferably ceramic) material is used for the seal faces and the seal faces are finished square to the axial centerline of the rotating union to provide correct, tight, lapped sealing surfaces. The wide spacing of the bearings and uniform spring loading of the dynamic seal faces minimizes seal face misalignment, thus further minimizing the possibility of material leakage across the dynamic seal assembly. In the event that material leakage does occur, the rotating union further includes a leakage collection area on the opposite side of the dynamic seal assembly. The leakage collection area is charged with a barrier fluid and is sealed so that the barrier fluid cannot contact the bearings. A passive barrier fluid circulating system is provided for removing barrier fluid from the leakage collection area along with material that leaks past the dynamic seal faces. The barrier fluid circulating system includes a barrier fluid reservoir that surrounds the sleeve and passages through which barrier fluid is circulated from the leakage collection area under the rotating action of the body.
In a second preferred embodiment, the rotating union of the invention includes a generally cylindrical body and a generally annular sleeve that is radially spaced from the body and rotatably coupled thereto via a pair of axially-spaced bearings. As with the first preferred embodiment, the body and the sleeve are formed with ports and interconnecting passages for transferring a material stream therethrough and these ports and passages communicate with each other via a material transfer interface that is dynamically sealed. Again, the seal faces are made from finely lapped (preferably ceramic) material and they are uniformly spring loaded to minimize seal misalignment. Unlike the first preferred embodiment, a pair of dynamic seal assemblies are provided, and they are positioned between the bearings such that seal rocking becomes nearly impossible. The second preferred embodiment also includes a pair of leakage collection areas located between the dynamic seal assemblies and the bearings. To prevent bearing damaging material from contacting the bearings, the leakage collection areas are charged with a barrier fluid and an active barrier fluid circulating system is provided for pumping barrier fluid through the bearings themselves and toward the dynamic seal assemblies. The barrier fluid is then removed from the leakage collection areas along with bearing damaging material that leaks past the dynamic seal faces.
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patent: 2425211 (1947-08-01), Strickland, Jr.
patent: 2450895 (1948-10-01), Keim
patent: 2460872 (1949-02-01), Carpenter
patent: 2701146 (1955-02-01), Warren
patent: 3017202 (1962-01-01), Swaney
patent: 4606560 (1986-08-01), McCracken
patent: 4635969 (1987-01-01),
Duft Walter W.
Walton George L.
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