Impeller for a centrifugal compressor

Abstract

An impeller for a centrifugal gas compressor includes a stationary seal member that includes a plurality of seal tips. The impeller is operable to produce a flow of fluid. The impeller includes a hub having a front face and a back face. A plurality of blades extends from the front face. Each of the blades has an inducer portion and an exducer portion and cooperates with an adjacent blade and the front face to at least partially define one of a plurality of impeller channels. A portion of the flow of fluid passes through one of the impeller channels such that the flow of fluid defines a first pressure adjacent the inducer portion and a second pressure that is higher than the first pressure adjacent the exducer portion. A seal portion extends from the back face and includes a plurality of stepped surfaces. Each of the seal tips is disposed adjacent one of the stepped surfaces to define a plurality of seal points.

1 . An impeller for a centrifugal gas compressor including a stationary seal member that includes a plurality of seal tips, the impeller operable to produce a flow of fluid, the impeller comprising: 
 a hub including a front face and a back face;    a plurality of blades extending from the front face, each of the blades having an inducer portion and an exducer portion and cooperating with an adjacent blade and the front face to at least partially define one of a plurality of impeller channels, a portion of the flow of fluid passing through one of the impeller channels such that the flow of fluid defines a first pressure adjacent the inducer portion and a second pressure that is higher than the first pressure adjacent the exducer portion; and    a seal portion extending from the back face and including a plurality of stepped surfaces, each of the seal tips disposed adjacent one of the stepped surfaces to define a plurality of seal points.    
   
   
       2 . The impeller of  claim 1 , wherein a bore extends from the front face to the back face.  
   
   
       3 . The impeller of  claim 1 , wherein a first stepped surface disposed adjacent the hub has a first diameter and a second stepped surface disposed away from the hub has a second diameter that is smaller than the first diameter, and wherein each additional stepped surface defines a surface diameter that is less than the diameter of the stepped surface on the hub side of the additional stepped surface and that is greater than the diameter of the stepped surface on the opposite side of the additional stepped surface.  
   
   
       4 . The impeller of  claim 1 , wherein each step includes a generally axially extending first portion and a generally radially extending second portion.  
   
   
       5 . The impeller of  claim 4 , wherein each seal tip cooperates with one of the axially extending first portion and the radially extending second portion to define a radial seal point and all axial seal point.  
   
   
       6 . The impeller of  claim 1 , wherein the seal portion divides the impeller back face into a first annular area and a second annular area, and wherein the first annular area interfaces with a first volume of gas at a pressure substantially the same as the gas discharged from the blades and the second annular area interfaces with a second volume of gas at a pressure substantially less than the gas discharged from the blades.  
   
   
       7 . The impeller of  claim 1 , wherein the blades, hub, and the seal portion are integrally-formed as a single component.  
   
   
       8 . The impeller of  claim 1 , wherein a sequence defined by corresponding radial dimensions of the steps in axial order, starting with a step nearest the blades decreases substantially uniformly.  
   
   
       9 . The impeller of  claim 1 , wherein the exducer defines an exducer diameter and the seal portion defines an average seal diameter that is greater than or equal to about 50 percent of the exducer diameter.  
   
   
       10 . An impeller for a centrifugal compressor including a stationary seal member having a plurality of first seal members, the impeller operable to produce a flow of fluid, the impeller comprising: 
 a hub including a front side, a back side, and a bore extending from the front side to the back side;    a plurality of blades extending from the front side, each blade including an inducer portion and an exducer portion, the exducer portion defining an outer diameter; and    a seal portion extending from the back face and including a plurality of second seal members, each of the first seal members disposed adjacent one of the second seal members to define a plurality of seal points, each of the seal points located at a seal point diameter, the average seal point diameter being greater than or equal to about 50 percent of the outer diameter.    
   
   
       11 . The impeller of  claim 10 , wherein each second seal member has a stepped surface, and wherein a first stepped surface is disposed adjacent the hub and has a first diameter, and a second stepped surface is disposed away from the hub and has a second diameter that is smaller than the first diameter, and wherein each additional stepped surface defines a surface diameter that is less than the diameter of the stepped surface on the hub side of the additional stepped surface and that is greater than the diameter of the stepped surface on the opposite side of the additional stepped surface.  
   
   
       12 . The impeller of  claim 10 , wherein each of the second seal members includes a generally axially extending first portion and a generally radially extending second portion.  
   
   
       13 . The impeller of  claim 12 , wherein each seal tip cooperates with one of the axially extending first portion and the radially extending second portion to define the radial seal point and an axial seal point.  
   
   
       14 . The impeller of  claim 10 , wherein the seal portion divides the impeller back face into a first annular area and a second annular area, and wherein the first annular area interfaces with a first volume of gas at a first pressure, and the second annular area interfaces with a second volume of gas at a second pressure substantially less than the first pressure.  
   
   
       15 . The impeller of  claim 10 , wherein the blades, hub, and the seal portion are integrally-formed as a single component.  
   
   
       16 . The impeller of  claim 10 , wherein each second seal member includes a step, and wherein a sequence defined by corresponding radial dimensions of the steps in axial order, starting with a step nearest the blades decreases substantially uniformly.  
   
   
       17 . A compressor comprising: 
 a motor;    an impeller including a hub that is coupled to the motor, the impeller rotatable in response to rotation of the motor and including a plurality of blades arranged to define an inducer portion and an exducer portion, the impeller operable to draw a flow of fluid into the inducer in a substantially axial direction and discharge the flow of fluid from the exducer in a substantially radial direction,    a rotating seal member extending from the impeller and spaced a non-zero distance from the hub; and    a stationary seal member positioned adjacent the rotating seal member and cooperating with the rotating seal member to define a plurality of seal points.    
   
   
       18 . The compressor system of  claim 17 , wherein one of the rotating seal member and the stationary seal member includes a plurality of surfaces and the other of the rotating seal member and the stationary seal member includes a plurality of teeth, and wherein each tooth is disposed adjacent one of the plurality of surfaces.  
   
   
       19 . The compressor system of  claim 18 , wherein the seal portion disposed nearest the blades defines a first diameter and each subsequent seal portion defines a surface diameter that is smaller is the distance of the surface from the blades increases.  
   
   
       20 . The compressor system of  claim 19 , wherein the diameter of the seal portions are substantially uniformly stepped.  
   
   
       21 . The compressor system of  claim 18 , wherein two adjacent seal portions are connected by a substantially radial surface, and wherein one of the plurality of teeth cooperates with one of the adjacent seal portions to define a radial seal and cooperates with the radial surface to define an axial seal.  
   
   
       22 . The compressor system of  claim 17 , wherein the exducer defines an exducer diameter and the rotating seal portion defines an average seal diameter that is greater than or equal to about 50 percent of the exducer diameter.