Multistage motor-compressor for the compression of a fluid

Abstract

A motor-compressor is provided that includes a first compression stage with a primary impeller and at least one delivery duct, a second compression stage with a secondary impeller spinning in a predetermined direction of rotation, and at least one transfer duct placed so as to put the delivery duct in communication with a fluid conveyor for the second stage. The transfer duct is shaped in a way to create a fluid flow entering the conveyor with a substantially helical course and a direction of rotation opposite to the direction of rotation of the secondary impeller.

1 . A multistage motor-compressor for compression of a fluid, comprising: 
 a first compression stage having a primary impeller and at least one delivery duct,    a second compression stage having a secondary impeller spinning in a first direction of rotation and a fluid conveyor, and    at least one transfer duct placing said at least one delivery duct in communication with said fluid conveyor, said at least one transfer duct being shaped in a way to create a fluid flow entering said fluid conveyor with a substantially helical course and with a direction of rotation opposite to said first direction of rotation.    
     
     
         2 . The motor-compressor according to  claim 1 , wherein said second compression stage comprises at least one axial inlet duct for said fluid flow, said fluid conveyor having an inlet opening for said fluid flow, said inlet opening being in communication with said at least one transfer duct and with said at least one axial inlet duct.  
     
     
         3 . The motor-compressor according to  claim 2 , wherein said at least one delivery duct comprises a pair of diametrically opposed delivery ducts, said fluid conveyor comprising a pair of diametrically opposed inlet openings, each inlet opening of said pair of inlet openings being in communication with a respective delivery duct of said pair of delivery ducts via a separate transfer duct.  
     
     
         4 . The motor-compressor according to  claim 2 , wherein said at least one delivery duct comprises three delivery ducts set at 120° to each other, said fluid conveyor comprising three inlet openings set at 120° to each other, each inlet opening of said three inlet openings being in communication with a respective delivery duct of said three delivery ducts via a separate transfer duct.  
     
     
         5 . The motor-compressor according to  claim 3 , wherein said primary and secondary impellers are driven by a driving device inside a casing, said separate transfer ducts being placed on an outside of said casing.  
     
     
         6 . The motor-compressor according to  claim 3 , wherein each of said separate transfer ducts comprises: 
 a first section connected to said respective delivery duct and substantially tangential to said primary impeller,    a second section connected to said fluid conveyor and substantially tangential to said secondary impeller, and    a longitudinal intermediate section.    
     
     
         7 . The motor-compressor according to  claim 6 , wherein each of said separate transfer ducts further comprises 
 a substantially helical section placed between said first tangential section and said intermediate section, and    a curved section placed between said second tangential section and said intermediate section.    
     
     
         8 . The motor-compressor according to  claim 7 , wherein each of said separate transfer ducts is subdivided into two segments, each segment of said two segments comprising a portion of said intermediate section and a flange for connection with the other segment of said two segments.  
     
     
         9 . The motor-compressor according to  claim 3 , wherein said separate transfer ducts are each shaped in a way to create said fluid flow exiting from said delivery ducts with a substantially helical course and with a third direction of rotation concordant with a direction of rotation of said primary impeller.  
     
     
         10 . The motor-compressor according to  claim 5 , wherein said driving device comprise a first electric motor for driving said primary impeller and a second electric motor for driving said secondary impeller.  
     
     
         11 . The motor-compressor according to one of the claims  5 , wherein said driving device comprises a common electric motor for said primary and secondary impellers.  
     
     
         12 . The motor-compressor according to  claim 11 , wherein said primary and secondary impellers are coaxial.  
     
     
         13 . The motor-compressor according to  claim 12 , wherein said primary and secondary impellers are fixed on two opposite ends of a shaft of said common electric motor.  
     
     
         14 . The motor-compressor according to  claim 11 , wherein said primary and secondary impellers spin around two axes that are coplanar and which form a predetermined angle.  
     
     
         15 . The motor-compressor according to  claim 11 , further comprising a drive transmission group placed between said common electric motor and said primary impeller and/or said secondary impeller.