Foil bearing supported motor-driven blower

Abstract

A high-speed blower designed to move and circulate dry process gas includes an axial or mixed-flow compressor driven by a brushless permanent magnet synchronous motor utilizing a remotely mounted variable frequency drive. The blower uses foil gas bearings which enable high-speed, low-power loss, and oil-free operation. The blower comprises an outer blower housing and an inner blower housing defining an annular cavity therebetween. A cooling flow of process gas may be leaked through the inner blower housing to cool the internal operational components of the blower, including the motor and the bearings, and to capture heat therefrom, which can be added to the process gas flow moving through the blower. Diffuser vanes and flow-straightening vanes are provided on the outer surface of the inner blower housing to improve the fluid dynamics of the process gas flow through the blower and heat transfer from the inner blower housing.

What is claimed is: 
     
         1 . A blower for moving dry process gas, comprising:
 an outer blower housing having an inlet and an outlet;   a flow compressor mounted within the outer blower housing at the inlet end thereof for rotation about an axis, whereby rotation of the flow compressor generates a dry process gas flow through the outer blower housing between the inlet and the outlet; and   an inner blower housing mounted within the outer blower housing adjacent to the flow compressor, said inner blower housing defining an internal passage between an inlet and an outlet thereof and including therein a motor, a rotating assembly operatively associated with the motor for rotating the rotating assembly about an axis, at least two journal bearing assemblies and at least one thrust bearing assembly;   wherein an annular cavity is defined between the outer blower housing and the inner blower housing, said inner blower housing includes a plurality of three-dimensional diffuser vanes mounted to the outer surface thereof and projecting into the annular cavity for redirecting the dry process gas flow passing through the annular cavity;   wherein said inner blower housing further includes a plurality of flow-straightening vanes mounted to the outer surface thereof downstream from the diffuser vanes and projecting into the annular cavity for guiding the dry process gas flow passing through the annular cavity; and   wherein the diffuser vanes and the flow-straightening vanes assist in heat transfer from the inner blower housing to the annular cavity during operation of the blower.   
     
     
         2 . The blower according to  claim 1 , wherein a portion of the dry process gas flow generated in the outer blower housing is leaked into the internal passage of the inner blower housing via the inlet thereof, said portion of the dry process gas flow passing through the internal passage and out of the outlet of the inner blower housing where said portion of dry process gas flow mixes with the dry process gas flow generated by the flow compressor. 
     
     
         3 . The blower according to  claim 2 , wherein the portion of the dry process gas flow passing through the internal passage of the inner blower housing is driven by a pressure difference between the inlet and the outlet of the inner blower housing. 
     
     
         4 . The blower according to  claim 3 , wherein the pressure difference between the inlet and the outlet of the inner blower housing is influenced by the affect on the dry process gas flow by the diffuser vanes and the flow-straightening vanes projecting into the annular cavity around the inner blower housing. 
     
     
         5 . The blower according to  claim 1 , wherein the flow compressor comprises a single-stage, axial flow compressor. 
     
     
         6 . The blower according to  claim 1 , wherein the flow compressor comprises a single-stage, mixed flow compressor. 
     
     
         7 . The blower according to  claim 1 , wherein the flow compressor is operatively connected to the rotating assembly so that rotation of the rotating assembly effects rotation of the flow compressor. 
     
     
         8 . The blower according to  claim 1 , wherein the rotating assembly is supported on at least one of hydrodynamic foil gas bearings, hydrostatic bearings, or oil-free ceramic-type bearings. 
     
     
         9 . The blower according to  claim 8 , wherein a portion of the dry process gas flow flowing through the outer blower housing is used to lubricate the bearings. 
     
     
         10 . The blower according to  claim 9 , wherein a portion of the dry process gas flow generated in the outer blower housing is leaked into the internal passage of the inner blower housing via the inlet thereof, said portion of the dry process gas flow passing through the internal passage to lubricate the bearings, and out of the outlet of the inner blower housing where said portion of dry process gas flow mixes with the dry process gas flow generated by the flow compressor. 
     
     
         11 . A blower for moving dry process gas, comprising:
 an outer blower housing having an inlet and an outlet;   a flow compressor mounted within the outer blower housing at the inlet end thereof for rotation about an axis, whereby rotation of the flow compressor generates a dry process gas flow through the outer blower housing between the inlet and the outlet; and   an inner blower housing mounted within the outer blower housing adjacent to the flow compressor, said inner blower housing defining an internal passage between an inlet and an outlet thereof and including therein a motor, a rotating assembly operatively associated with the motor for rotating the rotating assembly about an axis, at least two journal bearing assemblies and at least one thrust bearing assembly;   wherein an annular cavity is defined between the outer blower housing and the inner blower housing, said inner blower housing includes a plurality of three-dimensional diffuser vanes mounted to the outer surface thereof and projecting into the annular cavity for redirecting the dry process gas flow passing through the annular cavity and for assisting in heat transfer from the inner blower housing to the annular cavity during operation of the blower;   wherein a portion of the dry process gas flow generated in the outer blower housing is leaked into the internal passage of the inner blower housing via the inlet thereof, said portion of the dry process gas flow passing through the internal passage and out of the outlet of the inner blower housing where said portion of dry process gas flow mixes with the dry process gas flow generated by the flow compressor.   
     
     
         12 . The blower according to  claim 11 , wherein the portion of the dry process gas flow passing through the internal passage of the inner blower housing is driven by a pressure difference between the inlet and the outlet of the inner blower housing. 
     
     
         13 . The blower according to  claim 12 , wherein the pressure difference between the inlet and the outlet of the inner blower housing is influenced by the affect on the dry process gas flow by the diffuser vanes projecting into the annular cavity around the inner blower housing. 
     
     
         14 . The blower according to  claim 11 , further comprising a plurality of flow-straightening vanes mounted to the outer surface thereof downstream from the diffuser vanes and projecting into the annular cavity for guiding the dry process gas flow passing through the annular cavity and for assisting in heat transfer from the inner blower housing to the annular cavity during operation of the blower. 
     
     
         15 . The blower according to  claim 11 , wherein the flow compressor comprises a single-stage, axial flow compressor. 
     
     
         16 . The blower according to  claim 11 , wherein the flow compressor comprises a single-stage, mixed flow compressor. 
     
     
         17 . The blower according to  claim 11 , wherein the rotating assembly is supported on at least one of hydrodynamic foil gas bearings, hydrostatic bearings, or oil-free ceramic-type bearings. 
     
     
         18 . The blower according to  claim 17 , wherein a portion of the dry process gas flow flowing through the outer blower housing is used to lubricate the bearings. 
     
     
         19 . The blower according to  claim 18 , wherein a portion of the dry process gas flow generated in the outer blower housing is leaked into the internal passage of the inner blower housing via the inlet thereof, said portion of the dry process gas flow passing through the internal passage to lubricate the bearings, and out of the outlet of the inner blower housing where said portion of dry process gas flow mixes with the dry process gas flow generated by the flow compressor.