Elliptical sealing system

Abstract

Some embodiments of the invention are directed to an elliptical sealing system for use with a rotor and a stator housing of a rotary machine. The elliptical sealing system includes a plurality of sealing segments; and an abradable coating having a uniform thickness disposed on each of the plurality of sealing segments, such that the plurality of sealing segments with the abradable coating disposed thereon has a substantially elliptical shape under all conditions when the rotor rotates and the rotor remains stationary. A rotary machine having the elliptical sealing system is also disclosed.

1 . An elliptical sealing system for use with a rotor and a stator housing of a rotary machine, comprising:
 a plurality of sealing segments; and   an abradable coating having a uniform thickness disposed on each of the plurality of sealing segments, such that the plurality of sealing segments with the abradable coating disposed thereon has a substantially elliptical shape under all conditions when the rotor rotates and the rotor remains stationary.   
     
     
         2 . The elliptical sealing system of  claim 1 , wherein the plurality of sealing segments comprises a packing ring. 
     
     
         3 . The elliptical sealing system of  claim 1 , further comprising a plurality of biasing members mechanically coupled to the plurality of sealing segments and the stator housing. 
     
     
         4 . The elliptical sealing system of  claim 3 , wherein the plurality of biasing members is positioned at about a 12 o'clock position and at about a 6 o'clock position to bias the plurality of sealing segments towards the rotor. 
     
     
         5 . The elliptical sealing system of  claim 4 , wherein the plurality of biasing members positioned at about the 6 o'clock position is configured to effect an upward movement of an associated sealing segment when the rotor rotates. 
     
     
         6 . The elliptical sealing system of  claim 3 , wherein the plurality of biasing members comprises a plurality of springs to bias the plurality of sealing segments towards the rotor. 
     
     
         7 . The elliptical sealing system of  claim 1 , wherein the plurality of sealing segments comprises a first semielliptical sealing segment and a second semielliptical sealing segment. 
     
     
         8 . The elliptical sealing system of  claim 7 , wherein a first end of the first semielliptical sealing segment is mechanically coupled to a first end of the second semielliptical sealing segment at about a 3 o'clock position, and a second end of the first semielliptical sealing segment is mechanically coupled to a second end of the second semielliptical sealing segment at about a 9 o'clock position. 
     
     
         9 . The elliptical sealing system of  claim 7 , wherein coupling joints between the first semielliptical sealing segment and the second semielliptical sealing segment define a major axis of the substantially elliptical shape. 
     
     
         10 . The elliptical sealing system of  claim 1 , wherein the rotor comprises a plurality of teeth mounted thereon, and wherein the plurality of teeth engages the abradable coating. 
     
     
         11 . The elliptical sealing system of  claim 10 , wherein the plurality of teeth comprises a plurality of J-strips, and wherein the plurality of J-strips engages at different depths in the abradable coating along an inner circumference of the stator housing. 
     
     
         12 . The elliptical sealing system of  claim 10 , wherein the plurality of teeth and the abradable coating are configured such that the plurality of teeth defines an elliptical path in the abradable coating during an initial period of rotation. 
     
     
         13 . The elliptical sealing system of  claim 10 , wherein the plurality of teeth and the abradable coating are configured such that when the rotor rotates, an engagement of the plurality of teeth in the abradable coating, is deeper at about a 12 o'clock position when compared to an engagement at a 6 o'clock position. 
     
     
         14 . The elliptical sealing system of  claim 10 , wherein the plurality of sealing segments with the abradable coating disposed thereon has an interference engagement with the plurality of teeth at about a 12 o'clock position and at about a 6 o'clock position. 
     
     
         15 . The elliptical sealing system of  claim 10 , wherein the plurality of sealing segments with the abradable coating disposed thereon has a line on line engagement with the plurality of teeth at about a 3 o'clock position and at about a 9 o'clock position. 
     
     
         16 . The elliptical sealing system of  claim 1 , wherein the rotary machine comprises a compressor. 
     
     
         17 . A rotary machine, comprising:
 a stator housing;   a rotor comprising a plurality of teeth mounted thereon;   a first semielliptical sealing segment and a second semielliptical sealing segment mechanically coupled to each other at about a 3 o'clock position and about a 9 o'clock position, each of the first semielliptical sealing segment and the second semielliptical sealing segment comprising an abradable coating of a uniform thickness disposed thereon,   wherein the first semielliptical sealing segment and the second semielliptical sealing segment with the abradable coating disposed thereon have an elliptical shape under all conditions when the rotor rotates and the rotor remains stationary, and   wherein the abradable coating has an interference engagement with the plurality of teeth at about a 12 o'clock position and at about a 6 o'clock position, and the abradable coating has a line on line engagement with the plurality of teeth at about the 3 o'clock position and at about the 9 o'clock position.   
     
     
         18 . The rotary machine of  claim 17 , further comprising a plurality of biasing members mechanically coupled to the first semielliptical sealing segment, the second semielliptical sealing segment, and the stator housing, wherein the plurality of biasing members is positioned at about the 12 o'clock position and about the 6 o'clock position to bias the plurality of sealing segments towards the rotor. 
     
     
         19 . The rotary machine of  claim 17 , wherein the plurality of teeth and the abradable coating are configured such that the plurality of teeth define an elliptical path in the abradable coating when the rotor lifts-up during an initial period of rotation. 
     
     
         20 . The rotary machine of  claim 17 , wherein the plurality of teeth and the abradable coating are configured such that when the rotor rotates, an engagement of the plurality of teeth in the abradable coating, is deeper at about a 12 o'clock position when compared to an engagement at a 6 o'clock position.