Rotodynamic Fluid Machine

Abstract

A rotodynamic fluid machine includes a motor arranged for directly driving a shaft, a pressurized motor housing having end walls through which the shaft passes via dry gas seals to enclose the motor, elements for maintaining the pressure within the motor housing which pressure is different from the pressure outside the motor housing, a first impeller directly connected to one end of the motor driven shaft, arranged to move process fluid from an inlet to an outlet in a first direction relative to the shaft axis, a second impeller directly connected to the opposite end of the shaft, arranged to move process fluid from a second inlet to a second outlet in an opposite direction to the first direction relative to the shaft axis such that suction is created at both ends of the shaft, and a process fluid conduit connecting the first outlet to the second inlet.

1 . A rotodynamic fluid machine comprising a motor arranged for directly driving a shaft, a pressurised motor housing having end walls through which the shaft passes via dry seals to enclose the motor, means for maintaining the pressure within the motor housing different from the pressure outside the motor housing, a first impeller directly connected to one end of the motor driven shaft, arranged to move process fluid from an inlet to an outlet in a first direction relative to the shaft axis, a second impeller directly connected to the opposite end of the shaft, arranged to move process fluid from a second inlet to a second outlet, in an opposite direction to the first direction relative to the shaft axis, such that suction is created at both ends of the shaft, and a process fluid conduit connecting the first outlet to the second inlet.  
   
   
       2 . A rotodynamic fluid machine according to  claim 1  in which the pressure within the motor housing is also maintained different from the pressure of the process fluid.  
   
   
       3 . A rotodynamic fluid machine according to  claim 1  wherein the pressure within the motor housing is maintained higher than the pressure outside the motor housing.  
   
   
       4 . A rotodynamic fluid machine according to wherein the pressure within the motor housing is maintained higher than the pressure of the process fluid.  
   
   
       5 . A rotodynamic fluid machine according to  claim 1  wherein the dry seals are dry gas seals.  
   
   
       6 . A rotodynamic machine according to  claim 1  claims wherein each of the first and second impellers are arranged to pump process fluid generally towards the motor.  
   
   
       7 . A rotodynanic machine according to  claim 1  comprising a closed loop pressurised gas circulation system in fluid communication with a rotor part of the motor.  
   
   
       8 . A rotodynamic machine according to  claim 1 , further comprising a magnetic bearing supporting the shaft in the motor housing.  
   
   
       9 . A rotodynamic machine according to  claim 1 , wherein the shaft is integral with a rotor part of the motor.  
   
   
       10 . A rotodynamic machine according to  claim 1 , wherein the first impeller comprises a plurality of impeller stages and the second impeller comprises a plurality of impeller stages.  
   
   
       11 . A rotodynamic machine according to  claim 1  wherein the first and second impellers each comprise a diffuser unit.  
   
   
       12 . A rotodynamic machine according to  claim 1  wherein the diameter of the shaft is larger in the region of the motor and smaller in the region of the or each impeller.  
   
   
       13 . A rotodynamic machine according to  claim 1  wherein the motor is an electric motor.  
   
   
       14 . A pump comprising a rotodynamic machine according to  claim 1 .  
   
   
       15 . A rotodynamic fluid machine according to  claim 2  wherein the pressure within the motor housing is maintained higher than the pressure outside the motor housing.