Centrifugal pump with balancing device and a method of balancing axial forces of the centrifugal pump

Abstract

A single-stage or multi-stage centrifugal pump has a balancing disc for balancing the axial forces of the pump. The balancing disc includes at least one annular groove in at least one of the non-axial counter surfaces and of the balancing disc and the counter member.

1 . A centrifugal pump, comprising:
 a pump casing with an inlet and an outlet;   a shaft sealed and mounted with slide bearings to the pump casing, the shaft being movable in axial direction;   at least one impeller fastened on the shaft for rotation therewith and a balancing device configured to balance axial forces, the balancing device comprising a balancing disc fastened on the shaft for rotation therewith and having an outer circumference; and   a stationary counter member arranged in connection with the pump casing,   the balancing disc and the counter member forming therebetween a balancing cavity, the balancing disc having a first non-axial surface delimited to the outer circumference and the counter member having a second non-axial surface, the first and the second non-axial surfaces facing one another and forming a thin gap therebetween, at least one of the first and the second non-axial surfaces including at least one annular groove, a throttling being arranged downstream of the balancing disc and the counter member includes a counter ring having the second non-axial surface or the balancing disc includes an annular ring having the first non-axial surface.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The centrifugal pump in accordance with  claim 1 , wherein the at least one annular groove is a plurality of annular grooves, and at least one of the first and the second non-axial surfaces includes circular rings forming the plurality of annular grooves therebetween. 
     
     
         5 . The centrifugal pump in accordance with  claim 1 , wherein the annular groove has a depth of at least 10-fold to that of the thin gap. 
     
     
         6 . The centrifugal pump in accordance with  claim 1 , wherein the annular groove has a dimension of 1 to tens of millimeters in a direction at right angles to the first and the second non-axial surfaces. 
     
     
         7 . The centrifugal pump in accordance with  claim 1 , wherein the annular groove has a dimension of 1 to tens of millimeters in a direction parallel with the first and the second non-axial surfaces. 
     
     
         8 . The centrifugal pump in accordance with  claim 1 , wherein the counter member is a rear wall of the centrifugal pump. 
     
     
         9 . The centrifugal pump in accordance with  claim 1 , wherein the at least one annular groove is in the balancing disc, and the at least one annular groove faces is facing a groove in the counter member. 
     
     
         10 . The centrifugal pump in accordance with  claim 1 , wherein the throttling is arranged downstream of a cavity downstream of the balancing disc. 
     
     
         11 . The centrifugal pump in accordance with  claim 1 , wherein the throttling downstream of the balancing device is one of a slide bearing, a valve and a pipeline having a suitable cross sectional flow area. 
     
     
         12 . A method of balancing an axial thrust of a centrifugal pump in accordance with  claim 1 , the method comprising:
 arranging the throttling downstream of the balancing disc for controlling the amount of liquid leaking via the balancing device,   providing the counter member with the counter ring having the second non-axial surface, and   providing the balancing disc with the annular ring having the first non-axial surface.   
     
     
         13 . (canceled)