Centrifugal compressor including a seal system

Abstract

A centrifugal compressor includes an impeller that defines an outside diameter and is rotatable about an axis to provide a flow of compressed fluid. A portion of the compressed fluid passes around the outside diameter to define a leakage flow. An extension extends from the impeller and includes a first seal portion that has an average diameter that is greater than or equal to about 50 percent of the outside diameter. A stationary seal ring includes a second seal portion that has a plurality of teeth. The second seal portion is disposed adjacent the first seal portion to define a seal that inhibits the passage of the leakage flow.

1 . A centrifugal compressor comprising: 
 an impeller defining an outside diameter and rotatable about an axis to provide a flow of compressed fluid, a portion of the compressed fluid passing around the outside diameter to define a leakage flow;    an extension extending from the impeller and including a first seal portion having an average diameter that is greater than or equal to about 50 percent of the outside diameter;    a stationary seal ring including a second seal portion having a plurality of teeth, the second seal portion disposed adjacent the first seal portion to define a seal that inhibits the passage of the leakage flow.    
   
   
       2 . The centrifugal compressor of  claim 1 , wherein the first seal portion includes a plurality of steps.  
   
   
       3 . The centrifugal compressor of  claim 2 , wherein the number of steps substantially equals the number of teeth.  
   
   
       4 . The centrifugal compressor of  claim 2 , wherein a first of the plurality of steps defines a first step diameter and each of the subsequent steps in a leakage flow direction defines a diameter that is less than an adjacent upstream tooth.  
   
   
       5 . The centrifugal compressor of  claim 4 , wherein each tooth has a tip that defines a tip diameter and wherein the tip diameters of the teeth are reduced in the leakage flow direction such that each tooth tip cooperates with an adjacent step to define a substantially uniform gap.  
   
   
       6 . The centrifugal compressor of  claim 2 , wherein each step includes a generally radially-extending first portion and a generally axially-extending second portion.  
   
   
       7 . The centrifugal compressor of  claim 1 , wherein each tooth extends from the stationary seal element in a direction having both an axial component and a radial component.  
   
   
       8 . A centrifugal compressor comprising: 
 an impeller defining an outside diameter and rotatable about an axis to provide a flow of compressed fluid, a portion of the compressed fluid passing around the outside diameter to define a leakage flow;    an extension extending from the impeller and including a first seal portion having a plurality of steps in a leakage flow direction, a first of the plurality of steps having a first diameter with the diameter of each subsequent step being smaller than an adjacent upstream step;    a stationary seal ring including a second seal portion having a plurality of teeth, each tooth disposed adjacent one of the plurality of steps to define a plurality of seal points that inhibit the passage of the leakage flow.    
   
   
       9 . The centrifugal compressor of  claim 8 , wherein the number of steps substantially equals the number of teeth.  
   
   
       10 . The centrifugal compressor of  claim 8 , wherein each tooth has a tip that defines a tip diameter and wherein the tip diameters of the teeth are reduced in the leakage flow direction such that each tooth tip cooperates with an adjacent step to define a substantially uniform gap.  
   
   
       11 . The centrifugal compressor of  claim 8 , wherein each step includes a generally radially-extending first portion and a generally axially-extending second portion.  
   
   
       12 . The centrifugal compressor of  claim 8 , wherein each tooth extends from the stationary seal element in a direction having both an axial component and a radial component.  
   
   
       13 . The centrifugal compressor of  claim 8 , wherein the plurality of steps and the plurality of teeth cooperate to define an average seal diameter that is greater than or equal to about 50 percent of the outside diameter.  
   
   
       14 . A centrifugal compressor comprising: 
 an impeller defining an outside diameter and rotatable about an axis to provide a flow of compressed fluid, a portion of the compressed fluid passing around the outside diameter to define a leakage flow;    an extension extending from the impeller and including a first seal portion;    a housing coupled to the impeller to at least partially support the impeller for rotation, the housing including a first surface and a bore;    a stationary seal ring including a second seal portion, a second surface coupled to the first surface, and an alignment surface engaged with the bore, the alignment surface including a crush member that permanently deforms in response to engagement with the bore, the first surface, the second surface, the bore, and the alignment surface cooperating to position the second seal portion adjacent the first seal portion to define a seal.    
   
   
       15 . The centrifugal compressor of  claim 14 , wherein the first seal portion includes a plurality of steps and the second seal portion includes a plurality of teeth.  
   
   
       16 . The centrifugal compressor of  claim 15 , wherein the number of steps substantially equals the number of teeth.  
   
   
       17 . The centrifugal compressor of  claim 15 , wherein a first of the plurality of steps defines a first step diameter and each of the subsequent steps in a leakage flow direction defines a diameter that is less than an adjacent upstream step.  
   
   
       18 . The centrifugal compressor of  claim 15 , wherein each tooth has a tip that defines a tip diameter and wherein the tip diameters of the teeth are reduced in the leakage flow direction such that each tooth tip cooperates with an adjacent step to define a substantially uniform gap.  
   
   
       19 . The centrifugal compressor of  claim 15 , wherein each step includes a generally radially extending first portion and a generally axially extending second portion.  
   
   
       20 . The centrifugal compressor of  claim 15 , wherein each tooth extends from the stationary seal element in a direction having both an axial component and a radial component.  
   
   
       21 . The centrifugal compressor of  claim 14 , wherein the first seal portion and the second seal portion cooperate to define an average seal diameter that is greater than or equal to about 50 percent of the outside diameter.  
   
   
       22 . The stationary seal ring of  claim 14 , further comprising a shim having a selectable thickness and disposed between the first surface and the second surface, the thickness selected to define an axial position of the second seal portion with respect to the first seal portion.