Balance piston with a sealing member

Abstract

A balance piston for a compressor is provided. The balance piston may include an annular body and a seal extending from an axial surface of the annular body. The annular body may be configured to be disposed about and coupled with a rotary shaft of the compressor. The seal may be configured to form a sealing engagement with at least one component of the compressor to prevent a flow of a process fluid from an impeller of the compressor to a seal cavity of the compressor.

We claim: 
     
         1 . A balance piston for a compressor, comprising:
 an annular body configured to be disposed about and coupled with a rotary shaft of the compressor; and   a seal extending from an axial surface of the annular body and configured to form a sealing engagement with at least one component of the compressor to prevent a flow of a process fluid from an impeller of the compressor to a seal cavity of the compressor.   
     
     
         2 . The balance piston of  claim 1 , wherein the annular body is integral with an impeller of the compressor. 
     
     
         3 . The balance piston of  claim 1 , wherein the seal comprises a protrusion extending from the axial surface of the annular body. 
     
     
         4 . The balance piston of  claim 3 , wherein the protrusion is configured to form a sealing engagement with a shaft seal assembly of the compressor to prevent the flow of the process fluid from the impeller to the seal cavity. 
     
     
         5 . The compressor of  claim 4 , wherein the protrusion is configured to form the sealing engagement with a labyrinth seal of the shaft seal assembly. 
     
     
         6 . The compressor of  claim 5 , wherein the protrusion and the labyrinth seal define a tortuous path therebetween. 
     
     
         7 . The compressor of  claim 3 , wherein the protrusion extends annularly about the axial surface of the annular body. 
     
     
         8 . The compressor of  claim 3 , wherein an inner radial surface and an outer radial surface of the protrusion are substantially parallel with one another. 
     
     
         9 . The compressor of  claim 3 , wherein an inner radial surface of the protrusion is arcuate. 
     
     
         10 . The compressor of  claim 3 , wherein an outer radial surface of the protrusion is arcuate. 
     
     
         11 . A compressor, comprising:
 a casing;   a rotary shaft disposed in the casing and configured to be driven by a driver;   a shaft seal assembly disposed radially outward from the rotary shaft and at least partially defining a seal cavity;   an impeller coupled with the rotary shaft and configured to receive a process fluid and discharge the process fluid at an absolute Mach number of about 1.0 or greater;   a balance piston integral with the impeller;   a balance piston seal disposed radially outward from the balance piston such that the balance piston seal and the balance piston define a radial clearance therebetween; and   a protrusion coupled or integral with the balance piston and configured to prevent a flow of a process fluid from the radial clearance to the seal cavity,   wherein the compressor is configured to provide a compression ratio of at least about 8.1.   
     
     
         12 . The compressor of  claim 11 , wherein the protrusion extends from an axial surface of the balance piston seal. 
     
     
         13 . The compressor of  claim 12 , wherein the protrusion is configured to form a sealing engagement with a portion of the casing to prevent a portion of the process fluid discharged from the impeller from flowing to the seal cavity via the radial clearance. 
     
     
         14 . The compressor of  claim 12 , wherein the protrusion is configured to form a sealing engagement with the shaft seal assembly to prevent a portion of the process fluid discharged from the impeller from flowing to the seal cavity via the radial clearance. 
     
     
         15 . The compressor of  claim 14 , wherein the shaft seal assembly comprises a labyrinth seal disposed proximal the protrusion, and the protrusion is configured to form the sealing engagement with the labyrinth seal. 
     
     
         16 . The compressor of  claim 15 , wherein the protrusion and the labyrinth seal define a tortuous path therebetween. 
     
     
         17 . The compressor of  claim 12 , wherein the protrusion extends annularly about the axial surface of the balance piston seal. 
     
     
         18 . The compressor of  claim 12 , wherein an inner radial surface and an outer radial surface of the protrusion are substantially parallel with one another. 
     
     
         19 . The compressor of  claim 12 , wherein an inner radial surface or an outer radial surface of the protrusion is arcuate. 
     
     
         20 . A compression system, comprising:
 a driver; and   a compressor coupled with the driver via a drive shaft and configured to provide a compression ratio of at least about 8:1, the compressor comprising:
 a casing; 
 an inlet coupled or integral with the casing, the inlet and the casing at least partially defining a fluid pathway of the compressor, the fluid pathway configured to receive a process fluid; 
 a rotary shaft disposed in the casing and coupled with the driver via the drive shaft, the rotary shaft configured to be rotated by the driver via the drive shaft; 
 a shaft seal assembly disposed radially outward from the rotary shaft and at least partially defining a seal cavity; 
 an impeller coupled with the rotary shaft and configured to receive the process fluid and discharge the process fluid at an absolute Mach number of about one or greater; 
 a balance piston integral with the impeller; 
 a balance piston seal disposed radially outward from the balance piston such that the balance piston seal and the balance piston define a radial clearance therebetween; and 
 a protrusion coupled or integral with the balance piston and configured to prevent a flow of the process fluid from the radial clearance to the seal cavity.