Rotating element fluid seal for centrifugal compressor

Claim 2

In a seal arrangement for a centrifugal compressor having an impeller and in which the seal formed by the surfaces of an inner seal rotor and outer seal stator includes vent passage means formed in part at least in said rotor and extending from an intermediate location along the leakage path of the seal to an outlet located at the inlet side of the impeller, the improvement comprising: said vent passage means includes as a part thereof radially outwardly directed bore means between said rotor and said outlet of said passage means at the inlet side of said impeller to promote movement of fluid through said passage means by providing a centrifugal pumping action of said fluid in said radially outwardly directed bore means.

Claim 3

In an arrangement according to claim 1 wherein: said seal rotor includes an annular groove extending throughout the circumference of said rotor at said intermediate location to form at least said part of said vent passage in said rotor; said rotor includes a plurality of substantially axially directed bores connected to the inner circumference of said groove to complete said vent passage means in said rotor.

Claim 4

In an arrangement according to claim 1 wherein: said seal formed by said rotor and said stator includes one and another portion on opposite sides of said intermediate location, said one portion being of reduced diameter relative to said another portion.

Claim 5

In an arrangement according to claim 3 wherein: said another portion of said seal is inclined obliquely and radially outwardly from said intermediate location to the low pressure end of said leakage path.

Claim 6

In an arrangement according to claim 3 wherein: said leakage path formed by said one and said another portions of said seal extends substantially axially.

Claim 7

The combination of a seal arrangement according to claim 1 with apparatus in whicH the pressure at the end of said leakage path opposite the inlet side of said impeller is normally maintained at a pressure equal to or in excess of the pressure existing at the inlet side of said impeller, wherein: said outwardly directed bore means have a radial dimension sufficient to provide a pumping action creating sufficient suction pressure in said vent passage means to draw fluid through said part of said seal between the low pressure end of said leakage path to said vent passage means.

Claim 8

In a centrifugal compressor having a rotatable impeller, an inner seal rotor rotatable with said impeller and mounted on the impeller shaft, an outer seal stator, a vented seal arrangement for conducting fluid leakage along the leakage path of said seal to a location upstream of said impeller, comprising: a circumferential groove located intermediate of the axial extent of said seal and having its depth extending radially inwardly into said rotor; a plurality of generally axially extending bores in said rotor, each bore having one end in communication with the radially inner part of said groove and the other end in communication with an annular chamber in the hub of said impeller; and a plurality of bores in the hub of said impeller connecting said annular chamber with the space at the inlet side of said impeller, said last mentioned bores having a direction including a radially outwardly-directed component to provide a centrifugal pumping action tending to scavenge fluid leakage in said seal to said space at the inlet side of said impeller.

Claim 9

In a centrifugal compressor having a rotatable impeller, an inner seal rotor rotatable with said impeller and mounted on the impeller shaft, an outer seal stator, a vented seal arrangement for conducting fluid leakage along the leakage path of said seal to a location upstream of said impeller, comprising: a circumferential groove located intermediate of the axial extent of said seal and having its depth extending radially inwardly into said rotor; a plurality of generally axially extending bores in said rotor, each bore having one end in communication with the radially inner part of said groove and the other end in communication with an annular chamber in the hub of said impeller; and a plurality of bores in the hub of said impeller connecting said annular chamber with the space at the inlet side of said impeller, said last mentioned bores having a direction including a radially outwardly-directed component to provide a centrifugal pumping action tending to scavenge fluid leakage in said seal to said space at the inlet side of said impeller.