Compression or pumping device comprising a means of reducing the tangential velocity of the clearance flow

Abstract

A device for compressing or pumping a fluid, preferably a multiphase fluid, includes a stator, a rotor and a rotor shaft, each rotor being integral with the rotor shaft, each rotor comprising blades extending substantially radially to the longitudinal axis, and one at least is a shrouded rotor. The pump comprises a clearance between a shroud of the shrouded rotor and the housing allowing a clearance flow in the opposite direction to the fluid flow through the shrouded rotor. Furthermore, the stator comprises at least one arrangement for reducing the tangential velocity of the fluid from the clearance flow, positioned axially opposite the shroud of the shrouded rotor and/or said the clearance, upstream from the shrouded rotor.

1 . A device for compressing or for pumping a fluid, comprising a stationary part, at least one rotor and a rotor shaft, each rotor being integral with the rotor shaft, the rotor shaft being configured to be rotated about a longitudinal axis, each rotor comprising blades extending substantially radially to the longitudinal axis, and at least one of the at least one rotor being a shrouded rotor comprising a circumferential shroud connecting the peripheral radial tips of the blades, the stationary part comprising at least one stator and at least one external portion surrounding each rotor, the device comprising a clearance between the outer surface of each circumferential shroud of the shrouded rotor and the inner surface of the at least one external portion surrounding this shrouded rotor, allowing a clearance flow in the a direction opposite to a direction of principal fluid flow through the shrouded rotor, characterized in that the stator upstream from the shrouded rotor in the direction of the principal fluid flow through the shrouded rotor comprises a reduction means for reducing the tangential velocity of the fluid from the clearance flow, each reduction means being positioned axially opposite each shroud of the shrouded rotor and/or the clearance, upstream from the shrouded rotor in the direction of the principal fluid flow through the shrouded rotor. 
     
     
         2 . The device as claimed in  claim 1 , comprising several stators and/or several rotors. 
     
     
         3 . The device as claimed in  claim 1 , wherein each rotor comprises at least one series of blades, each series of blades comprising blades evenly distributed around the rotor shaft. 
     
     
         4 . The device as claimed in  claim 1 , comprising several shrouded rotors. 
     
     
         5 . The device as claimed in  claim 4 , wherein the circumferential shroud of the shrouded rotor extends longitudinally over a length allowing to cover at least one series of blades. 
     
     
         6 . The device as claimed in  claim 1 , wherein the circumferential shroud is circumferentially complete or circumferentially incomplete with at least one opening. 
     
     
         7 . The device as claimed in  claim 1 , wherein each reduction means consists of cavities in the stator intended to reduce the tangential velocity of the fluid from the clearance flow, the cavities facing an outlet of the fluid from the clearance flow, the cavities being circumferentially distributed over the stator and separated from one another by interfaces. 
     
     
         8 . The device as claimed in  claim 7 , wherein the cavities comprise grooves of crenellated shape or of triangular shape developed in the circumferential direction. 
     
     
         9 . The device as claimed in  claim 7 , wherein the number of cavities between two successive blades of the rotor opposite the reduction means ranges between 3 and 10. 
     
     
         10 . The device as claimed in  claim 7 , wherein the ratio of the cavity height to the blade height ranges between 10% and 40%. 
     
     
         11 . The device as claimed in  claim 7 , wherein the ratio of the cavity depth to the longitudinal length of the rotor ranges between 2% and 20%. 
     
     
         12 . A multiphase pump comprising the device as claimed in  claim 1 . 
     
     
         13 . (canceled) 
     
     
         14 . The device as claimed in  claim 3 , wherein each rotor comprises at least two series of blades following one another longitudinally. 
     
     
         15 . The device as claimed in  claim 10 , wherein the ratio of the cavity height to the blade height ranges between 15% and 25%. 
     
     
         16 . The device as claimed in  claim 11 , wherein the ratio of the cavity depth to the longitudinal length of the rotor ranges between 5% and 10%. 
     
     
         17 . A process, comprising extracting oil or gas from a geological reservoir by pumping the oil or gas with the device as claimed in  claim 1 . 
     
     
         18 . A process for injecting a fluid into a geological reservoir, comprising injecting the fluid into the geological reservoir by pumping the fluid with the device as claimed in  claim 1 . 
     
     
         19 . The device as claimed in  claim 2 , wherein the stators and the rotors follow one another alternately along the longitudinal axis. 
     
     
         20 . The device as claimed in  claim 4 , wherein the circumferential shroud of the shrouded rotor extends longitudinally over a length allowing to cover all the series of blades and wherein the length of each shroud equals the length of the rotor over which the shroud longitudinally extends. 
     
     
         21 . The device as claimed in  claim 7 , wherein some of the interfaces comprise stator blade extensions.