Magnetically coupled expander pump with axial flow path

Abstract

A magnetically coupled expander-pump assembly includes an outer expansion turbine that rotates around an inner fluid pump. A coaxial-type magnetic coupling couples the expansion turbine to the fluid pump. An inner portion of the magnetic coupling is coupled to a shaft that drives the fluid pump. An outer portion of the magnetic coupling is driven by the expansion turbine, which rotates circumferentially around the inner fluid pump. The expansion turbine is driven by a driving working fluid stream. The expansion turbine drives the fluid pump to pump a driven fluid stream through the magnetic coupling. In this manner, flow directions of both driving and driven fluid streams remain separate and coaxial, thereby facilitating a reduction in an overall diameter of the expander-pump assembly.

What is claimed is: 
     
         1 . An expander pump assembly comprising:
 a pump disposed in a pipe, the pump constructed to pump a first fluid; and   an expander disposed in an annular space surrounding the pipe, the expander driven by a second fluid flowing in the annular space; and   a magnetic coupling comprising an inner magnetic cylinder connected to the pump within the pipe, and an outer magnetic cylinder connected to the expander surrounding the pipe;   wherein the inner magnetic cylinder has open ends in fluid communication with the pump.   
     
     
         2 . The expander pump assembly according to  claim 1 , wherein the pump is constructed to pump the fluid coaxially with the pipe. 
     
     
         3 . The expander pump assembly according to  claim 1 , wherein the outer magnetic cylinder is disposed between the pipe and the expander. 
     
     
         4 . The expander pump assembly according to  claim 1 , wherein a portion of the pipe between the inner and outer magnetic cylinders is non-magnetic. 
     
     
         5 . The expander pump assembly according to  claim 3 , wherein the outer magnetic cylinder further includes a seal between the outer magnetic cylinder and the pipe. 
     
     
         6 . The expander pump assembly according to  claim 3 , wherein the expander further includes a seal between the expander and an outer wall of the annular space in which the expander is disposed. 
     
     
         7 . The expander pump assembly according to  claim 1 , wherein the expander is radially supported by fluid bearings. 
     
     
         8 . The expander pump assembly according to  claim 1 , wherein the expander is axially supported by at least one of thrust bearings and a pressure balance chamber. 
     
     
         9 . The expander pump assembly according to  claim 1 , wherein the pump is axially supported by at least one of thrust bearings and a pressure balance chamber. 
     
     
         10 . The expander pump assembly according to  claim 1 , wherein the pump is removably coupled to the inner magnetic cylinder. 
     
     
         11 . The expander pump assembly according to  claim 1 , wherein the pump includes a shaft extending through the inner magnetic cylinder, the shaft having at least one radial spoke extending from the shaft and connected to the inner magnetic cylinder. 
     
     
         12 . The expander pump assembly according to  claim 1 , wherein the expander includes at least one fluid impinging surface which receives the second fluid to impart a torque to rotate the outer magnetic cylinder. 
     
     
         13 . A fluid pump assembly comprising:
 a pump disposed in a pipe, the pump constructed to pump a first fluid; and   a pump driver constructed to drive the pump; and   a magnetic coupling comprising an inner magnetic cylinder connected to the pump within the pipe, and an outer magnetic cylinder connected to the pump driver surrounding the pipe;   wherein the inner magnetic cylinder has open ends in fluid communication with the pump.   
     
     
         14 . The fluid pump assembly according to  claim 13 , wherein the pump driver is an expander disposed in an annular space surrounding the pipe, the expander driven by a second fluid flowing in the annular space. 
     
     
         15 . The fluid pump assembly according to  claim 14 , wherein the expander includes at least one fluid impinging surface which receives the second fluid to impart a torque to rotate the outer magnetic cylinder. 
     
     
         16 . The fluid pump assembly according to  claim 14 , wherein the outer magnetic cylinder is connected to an inner annular surface of the expander. 
     
     
         17 . The fluid pump assembly according to  claim 13 , wherein the pump includes a shaft extending through the inner magnetic cylinder, the shaft having at least one radial spoke extending from the shaft and connected to the magnetic cylinder. 
     
     
         18 . The fluid pump assembly according to  claim 13 , wherein the pump is removably coupled to the inner magnetic cylinder. 
     
     
         19 . The fluid pump assembly according to  claim 14 , wherein the expander is radially supported by fluid bearings. 
     
     
         20 . The fluid pump assembly according to  claim 14 , wherein the expander is axially supported by at least one of thrust bearings and a pressure balance chamber. 
     
     
         21 . The fluid pump assembly according to  claim 13 , wherein the pump is axially supported by at least one of thrust bearings and a pressure balance chamber.