Retractable compliant abradable sealing system and method for rotary machines

Abstract

An abradable structure is provided on an inner face of a stationary component of the rotary machine or on a rotating component. During operation of the rotary machine, operating fluid pressure biases the stationary component against the rotating component, allowing minimal clearances to be maintained between the rotating component and the stationary component resulting in reduced fluid leakage and increased efficiency of the rotary machine. During start-up, shut down, or other transient conditions of the machine, a retractable mechanism biases the stationary component away from the rotating component ensuring preservation of a plurality of teeth provided on the stationary component or the rotating component.

1 . A rotary machine, comprising: 
 a first member;    a second member, wherein the first member is configured to rotate relative to the second member or the second member is configured to rotate relative to the first member; and    a retractable abradable seal disposed between the first and second members.    
   
   
       2 . The rotary machine of  claim 1 , wherein the retractable abradable seal configured to provide a generally zero-clearance labyrinth seal between the first and second members.  
   
   
       3 . The rotary machine of  claim 1 , wherein the retractable abradable seal comprises an abradable structure coupled to a retractable mechanism.  
   
   
       4 . The rotary machine of  claim 3 , wherein the retractable mechanism is recessed at least partially into the second member.  
   
   
       5 . The rotary machine of  claim 1 , wherein the retractable abradable seal comprises a retractable seal portion coupled to the second member and an abradable seal portion coupled to the first member opposite from the retractable seal portion.  
   
   
       6 . The rotary machine of  claim 1 , wherein the retractable abradable seal comprises an abradable seal portion disposed opposite from one or more sealing teeth.  
   
   
       7 . The rotary machine of  claim 6 , wherein the plurality of teeth are configured to form a plurality of permanent sealing grooves in the abradable seal portion.  
   
   
       8 . The rotary machine of  claim 7 , wherein the plurality of teeth are configured to engage the plurality of permanent sealing grooves formed in the abradable seal portion during normal operation of the machine.  
   
   
       9 . The rotary machine of  claim 1 , wherein the rotary machine comprises a turbine, a compressor, a combustor, or a combination thereof.  
   
   
       10 . The rotary machine of  claim 1 , wherein the rotary machine comprises a steam turbine.  
   
   
       11 . A system, comprising: 
 a retractable abradable seal, comprising:    a retractable mechanism configured to couple to a second member opposite from a first member, wherein the first member or the second member is configured to rotate;    a first seal portion disposed on the retractable mechanism; and    a second seal portion configured to be disposed on the first member and mate with the first seal portion, wherein the first seal portion or the second seal portion comprises an abradable structure.    
   
   
       12 . The system of  claim 11 , wherein the retractable abradable seal is configured to provide a generally zero-clearance labyrinth seal between the first and second members.  
   
   
       13 . The system of  claim 11 , wherein the first member comprises a rotary member.  
   
   
       14 . The system of  claim 11 , wherein the second member comprises a stationary member.  
   
   
       15 . The system of  claim 11 , wherein the abradable structure comprises an abradable coating.  
   
   
       16 . The system of  claim 11 , wherein the abradable structure comprises cobalt, or, nickel, or, chromium, or, aluminum, or, yttrium, or, hexagonal boron nitride, or polymers, or a combination thereof.  
   
   
       17 . The system of  claim 11 , wherein the abradable structure comprises nickel, or, chromium, or, aluminum, or clay, or a combination thereof.  
   
   
       18 . The system of  claim 11 , wherein the abradable structure comprises nickel, or, graphite, or, stainless steel, or a combination thereof.  
   
   
       19 . The system of  claim 11 , wherein the abradable structure comprises nickel, or, chromium, or, iron, or, aluminum, or, boron, or nitrogen, or a combination thereof.  
   
   
       20 . The system of  claim 11 , wherein the abradable structure comprises a plurality of drilled holes configured to reduce vibration.  
   
   
       21 . The system of  claim 11 , wherein the retractable mechanism comprises one or more springs configured to bias the first seal portion away from the second seal portion.  
   
   
       22 . The system of  claim 11 , wherein the retractable mechanism comprises one or more permanent magnets, or electromagnets configured to bias the first seal portion away from the second seal portion.  
   
   
       23 . The system of  claim 11 , wherein the first seal portion comprises the abradable structure and the second seal portion comprises one or more sealing teeth, or the first seal portion comprises one or more sealing teeth and the second seal portion comprises the abradable structure, or a combination thereof.  
   
   
       24 . The system of  claim 23 , wherein the plurality of sealing teeth are configured to form a plurality of permanent sealing grooves in the abradable structure.  
   
   
       25 . The system of  claim 24 , wherein the plurality of sealing teeth are configured to engage the plurality of permanent sealing grooves formed in the abradable structure during normal operation of the system.  
   
   
       26 . The system of  claim 11 , wherein the retractable mechanism is disposed at least partially in a gas chamber.  
   
   
       27 . The system of  claim 11 , wherein the retractable mechanism comprises a first stopper and a second stopper opposite the first stopper, and the first and second stoppers are configured to limit a range clearance between the first and second seal portions.  
   
   
       28 . A method, comprising: 
 rotating a first member relative to a second member or rotating the second member relative to the first member; and    providing a zero-clearance labyrinth seal between the first and the second members via a retractable abradable seal disposed between the first and the second members.    
   
   
       29 . The method of  claim 28 , wherein providing a zero-clearance labyrinth seal comprises biasing a retractable seal portion coupled to the second member against an abradable seal portion coupled to the first member.  
   
   
       30 . The method of  claim 28 , wherein providing a zero-clearance labyrinth seal comprises biasing an abradable seal portion coupled to the second member against one or more sealing teeth coupled to the first member.  
   
   
       31 . The method of  claim 30 , wherein providing a zero-clearance labyrinth seal comprises abrading a coating formed in the abradable seal portion to form a plurality of permanent sealing grooves in the coating.  
   
   
       32 . The method of  claim 30 , further comprising biasing the abradable seal portion away from one or more seal teeth via one or more springs.  
   
   
       33 . The method of  claim 30 , wherein providing a zero-clearance labyrinth seal comprises limiting a range clearance between the abradable seal portion and one or more sealing teeth via a first stopper and a second stopper.  
   
   
       34 . A method, comprising: 
 disposing a retractable abradable seal between a first member and a second member, comprising    coupling a retractable mechanism to the second member opposite from the first member, wherein the first member or the second member is configured to rotate;    disposing a first seal portion on the retractable mechanism; and    disposing a second seal portion on the first member to mate with the first seal portion; wherein the first seal portion or the second seal portion comprises an abradable structure.    
   
   
       35 . The method of  claim 34 , wherein disposing the retractable seal between the first and second members comprises providing a zero-clearance labyrinth seal between the first and second members.  
   
   
       36 . The method of  claim 34 , comprising providing an abradable coating on the first seal portion or the second seal portion.  
   
   
       37 . The method of  claim 34 , wherein coupling the retractable mechanism comprises providing one or more springs configured to bias the first seal portion away from the second seal portion.  
   
   
       38 . The method of  claim 37 , comprising disposing the retractable mechanism at least partially in a gas chamber.  
   
   
       39 . The method of  claim 37 , wherein disposing the retractable mechanism comprises providing a first stopper and a second stopper opposite the first stopper and configured to limit a range clearance between the first and second members.