Pump for transferring a liquefied gas

Abstract

A pump for transferring liquefied gas, including a pump body and a wheel having blades rotatably mounted inside the pump body, the pump has magnets arranged at the periphery of the wheel, the pump further including a field winding arranged to drive the wheel in rotation with the magnets.

1 . A pump for transferring liquefied gas, comprising:
 a pump body;   a wheel having blades rotatably mounted inside the pump body, each blade having a tip, the bladed wheel having permanent magnets arranged at the periphery of the wheel;   a field winding comprising a coil and arranged to drive the wheel in rotation with the magnets, the coil being embedded in an electrically insulating material; and   a sealing structure of annular shape arranged to provide sealing between two portions of the pump body, each of which portions is provided with a respective flange, sealing being provided when the two flanges are placed facing each other with the sealing structure clamped between them.   
     
     
         2 . The pump according to  claim 1 , wherein the field winding is arranged outside the pump body, facing the magnets and the periphery of the wheel. 
     
     
         3 . The pump according to  claim 1 , wherein the bladed wheel comprises a peripheral structure connecting together the tips of the blades, the magnets being secured to the peripheral structure and arranged so as to be substantially flush with a peripheral envelope of the wheel. 
     
     
         4 . The pump according to  claim 3 , wherein the peripheral structure is made out of a magnetic material, in particular out of a (ferro)magnetic stainless steel. 
     
     
         5 . The pump according to  claim 1 , wherein the magnets are in the form of portions of a cylindrical cap with a radius of curvature that matches the outside radius of the wheel. 
     
     
         6 . The pump according to  claim 1 , wherein the magnets are secured to the wheel by friction and/or abutment, in particular by mechanical blocking, or by crimping. 
     
     
         7 . The pump according to  claim 1 , wherein the bladed wheel is mounted to rotate freely on a stationary shaft rigidly connected to the pump body by a connection structure that is pierced by openings enabling liquefied gas to pass through the connection structure. 
     
     
         8 . The pump according to  claim 7 , wherein the connection structure includes a grid of stationary vanes arranged downstream from the wheel and serving to guide the gas flow. 
     
     
         9 . The pump according to  claim 7 , wherein the connection structure presents thermal conductivity that is less than the thermal conductivity of the wheel, than the thermal conductivity of the pump body, and/or than the thermal conductivity of the shaft. 
     
     
         10 . The pump according to  claim 7 , wherein the connection structure includes the sealing structure of annular shape. 
     
     
         11 . The pump according to  claim 7 , wherein the connection between the wheel and the stationary shaft is provided by a single bearing. 
     
     
         12 . The pump according to  claim 1 , wherein the wheel serves to move the pumped liquefied gas substantially along an axis of rotation of the wheel. 
     
     
         13 . The pump according to  claim 1 , wherein the pump body includes a central tubular structure defining a chamber in which the wheel is received, at least a portion of the tubular structure, which extends between the field winding and the periphery of the wheel, being made out of a non-magnetic material, the chamber presenting a cylindrical shape of diameter that is little greater than the diameter of the wheel. 
     
     
         14 . The pump according to  claim 13 , wherein the pump body also has two flared portions arranged on either side of and in line with the central tubular structure. 
     
     
         15 . A cryogenic axial flow pump comprising:
 a pump body;   a wheel having a row of blades arranged in annular cascade, each blade having a tip, the bladed wheel being rotatably mounted inside the pump body and having permanent magnets arranged at the periphery of the wheel, the bladed wheel being mounted to rotate freely on a stationary shaft rigidly connected to the pump body by a connection structure that is pierced by openings enabling liquefied gas to pass through the connection structure, the bladed wheel serving to move pumped liquefied gas substantially along an axis of rotation of the wheel;   a field winding comprising a coil and arranged to drive the wheel in rotation with the magnets, the coil being embedded in an electrically insulating material; and   a sealing structure of annular shape arranged to provide sealing between two portions of the pump body, each of which portions is provided with a respective flange, sealing being provided when the two flanges are placed facing each other with the sealing structure clamped between them.   
     
     
         16 . The pump according to  claim 15 , wherein the field winding is arranged outside the pump body, facing the magnets and the periphery of the wheel. 
     
     
         17 . The pump according to  claim 15 , wherein the bladed wheel comprises a peripheral structure connecting together the tips of the blades, the magnets being secured to the peripheral structure and arranged so as to be substantially flush with a peripheral envelope of the wheel. 
     
     
         18 . The pump according to  claim 17 , wherein the peripheral structure is made out of a magnetic material such as a (ferro)magnetic stainless steel. 
     
     
         19 . The pump according to  claim 15 , wherein the magnets are in the form of portions of a cylindrical cap with a radius of curvature that matches the outside radius of the wheel. 
     
     
         20 . The pump according to  claim 15 , wherein the magnets are secured to the wheel by friction, by abutment, by mechanical blocking, or by crimping. 
     
     
         21 . The pump according to  claim 15 , wherein the connection structure includes a grid of stationary vanes arranged downstream from the wheel and serving to guide the gas flow. 
     
     
         22 . The pump according to  claim 15 , wherein the connection structure presents thermal conductivity that is less than the thermal conductivity of the wheel, than the thermal conductivity of the pump body, and/or than the thermal conductivity of the shaft. 
     
     
         23 . The pump according to  claim 15 , wherein the connection structure includes the sealing structure of annular shape. 
     
     
         24 . The pump according to  claim 15 , wherein the connection between the wheel and the stationary shaft is provided by a single bearing. 
     
     
         25 . The pump according to  claim 15 , wherein the pump body includes a central tubular structure defining a chamber in which the wheel is received, at least a portion of the tubular structure, which extends between the field winding and the periphery of the wheel, being made out of a non-magnetic material, the chamber presenting a cylindrical shape of diameter that is little greater than the diameter of the wheel. 
     
     
         26 . The pump according to  claim 25 , wherein the pump body also has two flared portions arranged on either side of and in line with the central tubular structure. 
     
     
         27 . A method of pumping a liquefied gas having a temperature situated in a range from about minus two hundred degrees Celsius (200° C.) to about minus fifty degrees Celsius (50° C.) wherein use is made of a pump according to  claim 1 .