Submersible motor pump, motor pump, and tandem mechanical seal

Abstract

A submersible motor pump includes a water jacket having a circulation passage of a coolant, a centrifugal impeller for circulating the coolant, a suction passage configured to provide fluid communication between the circulation passage and a fluid inlet of the centrifugal impeller, and a discharge passage configured to provide fluid communication between a fluid outlet of the centrifugal impeller and the circulation passage. The discharge passage includes a heat-exchange passage formed by two wall surfaces, one of which is constituted by a member which contacts a liquid conveyed by a main impeller. The heat-exchange passage has a circular shape extending radially outwardly from the fluid outlet of the centrifugal impeller. The heat-exchange passage includes at least one axial passage section having a length component in an axial direction of the rotational shaft.

1 - 15 . (canceled) 
     
     
         16 . A tandem mechanical seal for use in a rotary machine having a rotational shaft, comprising:
 a first seal unit having a first sleeve to be mounted on the rotational shaft, a first rotary seal ring rotatable together with said first sleeve, a first stationary seal section contacting said first rotary seal ring, and a first spring mechanism configured to press said first rotary seal ring and said first stationary seal section against each other; and   a second seal unit having a second sleeve to be mounted on the rotational shaft, a second rotary seal ring rotatable together with said second sleeve, a second stationary seal section contacting said second rotary seal ring, a second spring mechanism configured to press said second rotary seal ring and said second stationary seal section against each other, and a centrifugal impeller rotatable together with said second sleeve,   wherein an end surface of said first sleeve and an end surface of said second sleeve are brought into contact with each other when said first seal unit and said second seal unit are mounted on the rotary machine, and   wherein said centrifugal impeller is located between a sealing surface of said first seal unit and a sealing surface of said second seal unit.   
     
     
         17 . The tandem mechanical seal according to  claim 16 , wherein said first seal unit further includes a first displacement restriction mechanism configured to restrict a displacement of said first stationary seal section with respect to said first sleeve, and said first displacement restriction mechanism is arranged in a position such that contact between said first rotary seal ring and said first stationary seal section is maintained by stretch of said first spring mechanism. 
     
     
         18 . The tandem mechanical seal according to  claim 16 , wherein said first stationary seal section has a first stationary seal ring contacting said first rotary seal ring and a first static member to be secured to the rotary machine. 
     
     
         19 . The tandem mechanical seal according to  claim 16 , wherein:
 said second spring mechanism is located between said second sleeve and said second rotary seal ring; and   said second seal unit further includes a second displacement restriction mechanism configured to couple said second sleeve and said second rotary seal ring to each other and to restrict a displacement of said second rotary seal ring with respect to said second sleeve.   
     
     
         20 . The tandem mechanical seal according to  claim 16 , wherein said second stationary seal section has a second stationary seal ring contacting said second rotary seal ring and a second static member to be secured to the rotary machine. 
     
     
         21 . The tandem mechanical seal according to  claim 16 , wherein:
 said first sleeve has a first positioning surface brought into contact with a first step surface formed on the rotational shaft; and   said second sleeve has a second positioning surface brought into contact with a second step surface formed on the rotational shaft.   
     
     
         22 . The tandem mechanical seal according to  claim 16 , wherein said second spring mechanism is provided on a boss of said centrifugal impeller.