Lubrication-free centrifugal compressor

Abstract

A gas compression compact device comprised of: a) one or more centrifugal compressors; and b) a high speed axial flow permanent magnet synchronous electric motor. The electric motor and the compressor are directly coupled on a single axis and supported by passive magnetic and electrodynamic bearings, free of lubrication. The equipment does not use mechanic seals since the rotor is placed inside the pressure containment of the gas. The equipment does not require auxiliary systems for cooling, filtration, separation or feeding of lubricant fluids.

What is claimed is: 
     
         1 . A compact gas compressing device comprising a rotating motor-impeller assembly formed by one or more centrifugal compressor impellers ( 1 ) and an electric motor ( 2 ), in which the one or more compressor impellers are coupled directly and on a single axis ( 5 ) to the electric motor ( 2 ), wherein said electric motor ( 2 ) is a synchronous, axial flow and permanent magnet motor. 
     
     
         2 . The compact gas compression device in accordance with  claim 1 , wherein the axis ( 5 ) of the rotating motor-impeller assembly is supported by two or more magnetic radial bearings ( 6 ,  7 ) to fix the radial position of the axis ( 5 ), and one or more passive electrodynamic thrust bearings ( 8 ,  9 ) to fix the axial position of the axis, and wherein the magnetic radial bearings ( 6 ,  7 ) and the one or more electrodynamic thrust bearings ( 8 ,  9 ) operate totally free of lubricants and of auxiliary control systems. 
     
     
         3 . The compact gas compression device in accordance with  claim 1 , wherein each one of said one or more electric motors ( 2 ) are formed by one or more stator assemblies ( 4 ) located between one or more rotating assemblies ( 3 ) which are fixed to the axis ( 5 ); and wherein the stator assemblies ( 4 ) contain one or more coils ( 10 ) and the rotating assemblies ( 3 ) contain one or more pairs of permanent magnets ( 12 ). 
     
     
         4 . The compact gas compression device in accordance with  claim 4 , wherein the one or more stator assemblies ( 4 ) further comprise part of the ferromagnetic core ( 11 ). 
     
     
         5 . The compact gas compression device in accordance with  claim 3 , wherein some of the one or more rotating assemblies ( 3 ) have ferromagnetic cores ( 11 ). 
     
     
         6 . The compact gas compression device in accordance with  claim 3 , wherein said one or more coils receive current pulses activated by a control electronic device ( 19 ) which monitors the position of magnets ( 12 ), 
     
     
         7 . The compact gas compression device in accordance with  claim 3 , wherein said control device ( 19 ) comprises semiconductors of the group including, among others: mosfet, IGBT, SSR. 
     
     
         8 . The compact gas compression device in accordance with  claim 2 , wherein each one of the magnetic radial bearings ( 6 ,  7 ) is formed by a rotating section comprising one or more permanent magnets with ring geometry fixed to the axis ( 5 ) and a stator section also formed by one or more permanent magnets with ring or cylinder geometry and that circumferentially surround the rotating section; and wherein both sections are separated by an elastic force of magnetic repulsion. 
     
     
         9 . The compact gas compression device in accordance with  claim 2 , wherein each one of said electrodynamic thrust bearings ( 8 ,  9 ) is formed by a rotating section fixed to the axis ( 5 ) and formed by two or more discs ( 8 ) that contain permanent magnets and ferromagnetic cores; and a static section fixed to the housing of the device and formed by a solid or perforated conducting disc ( 9 ) which is located between both rotating discs ( 8 ) and which comprises the conducting material; and wherein the relative movement between the rotating discs ( 8 ) and said conducting material induces electrical currents that generate repulsion forces against said magnets. 
     
     
         10 . The compact gas compression device in accordance with  claim 2 , wherein each one of said electrodynamic thrust bearings is formed by a static section fixed to housing of the device and formed by two or more discs that contain permanent magnets and ferromagnetic cores; and a rotating section fixed to the rotating axis of the device and formed by a solid or perforated conducting disc placed between said static discs and comprising conducting material; and wherein the relative movement between static discs and said conducting material induces electric currents thereon that generate repulsion forces against said magnets. 
     
     
         11 . The compact gas compression device in accordance with  claim 1  or  2 , wherein said rotating motor-impeller assembly, said magnetic radial bearings ( 6 ,  7 ) and said electrodynamic thrust bearings ( 9 ,  10 ) are placed inside the pressure containment of process gas ( 16 ), in a totally water tight container which is free of mechanical seals. 
     
     
         12 . The compact gas compression device in accordance with  claim 1  or  2 , wherein the same process gas is used as a coolant for said electric motor ( 2 ) and said magnetic radial bearings ( 6 ,  7 ) and said electrodynamic thrust bearings ( 8 ,  9 ). 
     
     
         13 . The compact gas compression device in accordance with  claim 1 , wherein the same process gas is used as a coolant for the power electronics ( 19 ) driving the electric motor. 
     
     
         14 . The compact gas compression device in accordance with  claim 1 , wherein the device is free of auxiliary systems for cooling, filtration, separation or feeding of any kind of lubricants. 
     
     
         15 . The compact gas compression device in accordance with  claim 1 , wherein the device comprises a compressor impeller ( 1 ) and an electric motor ( 2 ). 
     
     
         16 . The compact gas compression device in accordance with  claim 1 , wherein the device comprises two or more compressor impellers ( 1 ) and one electric motor ( 2 ). 
     
     
         17 . The compact gas compression device in accordance with  claim 2 , wherein the motor-impeller rotating assembly is mounted on an axis ( 5 ) supported by two magnetic radial bearings ( 6 ,  7 ) and a passive electrodynamic thrust bearing ( 9 ,  10 ). 
     
     
         18 . The compact gas compression device in accordance with  claim 2 , wherein the motor-impeller rotating assembly is mounted on an axis ( 5 ) supported by two magnetic radial bearings ( 6 ,  7 ) and two or more passive electrodynamic thrust bearings ( 9 ,  10 ). 
     
     
         19 . The compact gas compression device in accordance with  claim 2 , wherein the motor-impeller rotating assembly is mounted on an axis ( 5 ) supported by more than two magnetic radial bearings ( 6 ,  7 ) and two or more passive electrodynamic thrust bearings ( 9 ,  10 ).