Assembly for compensating axial forces in a rotating flow machine and a multi-stage centrifugal pump

Abstract

An assembly includes a housing, a shaft rotatably around the housing, a rotationally symmetrical balancing part arranged coaxially with the shaft, the balancing part having first and second axial ends, a first mechanical slide ring sealing between the balancing part and the housing at the first axial end, a second mechanical slide ring sealing between the balancing part and the housing at the second axial end, the first and the second mechanical slide ring sealings sealing an intermediate space, extending axially between the mechanical slide ring sealings, the intermediate space bordered by the slide ring sealings, the balancing part and the housing, and a first fluid communication port opening into the intermediate space, the first fluid communication port connected to a source of pressurized barrier fluid, and the first and second axial ends having a first and second radii, the first radius being equal to the second radius.

1 . An assembly for compensating axial forces in a rotating flow machine, comprising:
 a housing;   a shaft rotatably arranged to the housing;   a rotationally symmetrical balancing part arranged to and coaxially with the shaft in the housing;   the balancing part having a first axial end and a second axial end;   a first mechanical slide ring sealing arranged between the balancing part and the housing at the first axial end;   a second mechanical slide ring sealing arranged between the balancing part and the housing at the second axial end,   the first and the second mechanical slide ring sealings arranged so as to seal an intermediate space, extending axially between the mechanical slide ring sealings, the intermediate space being bordered by the slide ring sealings, the balancing part and the housing; and   a first fluid communication port opening into the intermediate space,   the first fluid communication port being connected to a source of pressurized barrier fluid, and the first axial end has a first radius and the second axial end has a second radius, the first radius being equal to the second radius.   
     
     
         2 . The assembly for compensating axial forces in a rotating flow machine according to  claim 1 , further comprising a second communication port opening into the intermediate space, and a fluid circulation channel connecting the first fluid communication port and the second communication port with each other. 
     
     
         3 . The assembly for compensating axial forces in a rotating flow machine according to  claim 2 , wherein the fluid circulation channel is connected to a source of pressurized fluid. 
     
     
         4 . The assembly for compensating axial forces in a rotating flow machine according to  claim 1 , further comprising a second communication port opening into the intermediate space and the second fluid communication port being connected to a fluid discharge system. 
     
     
         5 . The assembly for compensating axial forces in a rotating flow machine according to  claim 2 , wherein the circulation channel is fluidly connected to a working space of the rotating flow between an inlet and an outlet. 
     
     
         6 . The assembly for compensating axial forces in a rotating flow machine according to  claim 1 , wherein the housing comprises a cylindrical inner surface, and the balancing part comprises a cylindrical outer surface, the cylindrical inner surface of the housing and the cylindrical outer surface of the balancing part form a radial slide bearing between the balancing part and the housing. 
     
     
         7 . The assembly for compensating axial forces in a rotating flow machine according to  claim 6 , wherein the cylindrical inner surface of the housing and the cylindrical outer surface of the balancing part forming the slide bearing are comprised of removable sleeves having an axial length equal to axial lengths of the cylindrical inner surface of the housing and the cylindrical outer surface of the balancing part. 
     
     
         8 . The assembly for compensating axial forces in a rotating flow machine according to  claim 1 , wherein the first mechanical slide ring sealing comprises a first stationary sealing ring supported to the housing in an axially movable manner, a spring element configured to cause an axial force to the first stationary sealing ring to urge the first stationary sealing ring towards the balancing part, and the second slide ring sealing comprises a second stationary sealing ring supported to the housing in an axially movable manner, a spring element configured to cause an axial force to the second stationary sealing ring to urge the second stationary sealing ring towards the balancing part. 
     
     
         9 . The assembly for compensating axial forces in a rotating flow machine according to  claim 8 , wherein the balancing part includes a ring member configured to cooperate with the first stationary sealing ring and the second stationary sealing ring. 
     
     
         10 . A multi-stage centrifugal pump, comprising: having
 a drive shaft;   a plurality of impellers arranged to the drive shaft, and   the assembly for compensating axial forces according to  claim 1 .   
     
     
         11 . The multi-stage centrifugal pump according to  claim 10 , further comprising a second communication port opening into the intermediate space, and a fluid circulation channel connecting the first fluid communication port and the second communication port with each other, and the circulation channel is connected to a stage of the pump between a first and a last stage of the pump. 
     
     
         12 . The multi-stage centrifugal pump according to  claim 10 , wherein the circulation channel is connected to the centrifugal pump at a location which provides 30-70% of a maximum pressure of the pump. 
     
     
         13 . The assembly for compensating axial forces in a rotating flow machine according to  claim 3 , wherein the circulation channel is fluidly connected to a working space of the rotating flow between an inlet and an outlet.