Canned rotodynamic flow machine for a molten salt nuclear reactor and an active magnetic bearing for use in a flow machine for a molten salt nuclear reactor
A canned rotodynamic flow machine ( 1 ) configured for operating with a working fluid such as molten salt of a molten salt nuclear reactor. The stator windings are formed by one or more electrically conductive solid bars ( 12 ).
1 . A canned rotodynamic flow machine ( 1 ) configured for operating with a molten salt or a cover gas working fluid at temperatures above 500° C., said canned rotodynamic flow machine ( 1 ) comprising:
an impeller ( 6 ) arranged in a volute ( 3 ), said volute ( 3 ) having an inlet ( 4 ) for said working fluid and an outlet ( 5 ) for said working fluid,
an induction or reluctance motor or generator comprising:
a stator ( 10 ), a rotor ( 8 ),
a can ( 18 ) in the form of a containment shell which separates a working fluid area from a dry area containing the stator ( 10 ), with the rotor ( 8 ) arranged in the working fluid area, said rotor ( 8 ) being operably coupled to said impeller ( 6 ) by a shaft ( 7 ), said stator ( 10 ) comprising stator windings for inducing a magnetic field that penetrates the rotor ( 8 ), said stator windings being distributed in slots ( 11 ) arranged in said stator ( 10 ), wherein the part of the stator windings inside said slots ( 11 ) is formed by one or more electrically conductive solid stator bars ( 12 ),
one or more active magnetic bearings supporting said shaft ( 7 ),
wherein said one or more active magnetic bearings comprise:
a bearing stator ( 110 , 210 ) and a bearing rotor ( 108 , 208 ), said bearing stator ( 110 , 210 ) comprising bearing stator windings for inducing a magnetic field that penetrates said bearing rotor ( 108 , 208 ), said bearing stator windings being distributed in one or more slots ( 111 , 211 ) arranged in said bearing stator ( 110 , 210 ),
the part of the bearing stator windings inside said one or more slots ( 111 , 211 ) being formed by one or more electrically conductive solid bearing bars ( 112 , 212 ), said dry area containing the bearing stator ( 110 , 210 ), with the bearing rotor ( 108 , 208 ) arranged in the working fluid area.
2 . A canned rotodynamic flow machine ( 1 ) according to claim 1 , wherein said solid bearing bars ( 112 , 212 ) are positioned and held inside said slots ( 111 , 211 ) by one or more spacers ( 113 , 213 ) for electrically insulating said one or more solid bearing bars ( 112 , 212 ) from said stator ( 110 , 210 ) by spacing.
3 . A canned rotodynamic flow machine ( 1 ) according to claim 2 , wherein said spacers ( 113 , 213 ) are configured to space said solid bearing bars ( 112 , 212 ) from walls of said slot ( 111 , 211 ) and/or from other solid bearing bars ( 112 , 212 ) in the slot ( 111 , 211 ) concerned.
4 . A canned rotodynamic flow machine ( 1 ) according to claim 3 , wherein said spacers ( 113 , 213 ) support said solid bearing bars ( 112 , 212 ) locally and wherein said spacers ( 113 , 213 ) are provided at two or more axially spaced positions along the length of said solid bearing bars ( 112 , 212 ) in the slot ( 111 , 211 ) concerned.
5 . A canned rotodynamic flow machine ( 1 ) according to claim 1 , wherein said solid bearing bars ( 112 , 212 ) have a cross-sectional area of at least 5 mm 2 .
6 . A canned rotodynamic flow machine ( 1 ) according to claim 2 , wherein said solid bearing bars ( 112 , 212 ) are sufficiently rigid to maintain their shape under influence of magnetic forces generated when said motor or generator is operating, without coming in contact with the walls of the slot ( 111 , 211 ) in which they are received, and without coming in contact with other solid bearing bars ( 112 , 212 ) in the slot ( 111 , 211 ) in which they are received, with said solid bearing bars ( 112 , 212 ) being supported in said slot ( 111 , 211 ) by said spacers ( 113 , 213 ) only.
7 . A canned rotodynamic flow machine ( 1 ) according to claim 2 , wherein said solid bearing bars ( 112 , 212 ) are positioned inside said slots ( 111 , 211 ) by at least two spacers ( 113 , 213 ) that space the surface of said solid bearing bars ( 112 , 212 ) from the surface of said slots ( 111 , 211 ) and create a void between the surface of solid bearing bars ( 112 , 212 ) and the surface of said slots ( 111 , 211 ) for electrically insulating said one or more electrically conductive solid bearing bars ( 112 , 212 ) from said stator ( 110 , 210 ).
8 . An active magnetic bearing for use in a canned flow machine that operates with a working fluid, said active magnetic bearing being configured to operate in an environment having a temperature above 500° C., said active magnetic bearing comprising:
a stator ( 110 , 210 ) and a rotor ( 108 , 208 ),
said stator ( 110 , 210 ) comprising stator windings for inducing a magnetic field that penetrates said rotor ( 108 , 208 ),
means ( 201 , 202 ) for detecting the position of said rotor ( 108 , 208 ) in communication with a controller configured for controlling a current supply to said stator windings,
said stator windings being distributed in one or more slots ( 111 , 211 ) arranged in said stator ( 110 , 210 ),
the part of the stator windings inside said one or more slots ( 111 , 211 ) being formed by one or more electrically conductive solid bearing bars ( 112 , 212 ),
characterized by
said solid bearing bars ( 112 , 212 ) being positioned inside said slots ( 111 , 211 ) by one or more spacers ( 113 , 213 ) for electrically insulating said one or more electrically conductive solid bearing bars ( 112 , 212 ) from said stator ( 110 , 210 ),
a can ( 18 ), separating a working fluid area, from a dry area containing the stator ( 110 , 210 ), with the rotor ( 108 , 208 ) arranged in the working fluid area.
9 . An active magnetic bearing according to claim 8 , wherein said active magnetic bearing is a radial bearing and said slots ( 111 , 211 ) and said solid bearing bars ( 112 ) extend in said stator ( 110 ) along a straight line, or wherein said active magnetic bearing is an axial bearing and said slots ( 211 ) are circumferentially extending slots and said solid bearing bars ( 212 ) extend inside the circumferentially extending slots in said stator ( 210 ).
10 . An active magnetic bearing according to claim 8 , wherein said spacers ( 113 , 213 ) are configured to space said solid bearing bars ( 112 , 212 ) from walls of said slot ( 111 , 211 ) and/or from other solid bearing bars ( 112 , 212 ) in the slot ( 111 , 211 ) concerned.
11 . An active magnetic bearing according to claim 8 , wherein said spacers ( 113 , 213 ) support said solid bearing bars ( 112 , 212 ) locally and wherein said spacers ( 113 , 213 ) are provided at two or more axially spaced positions along the length of said solid bearing bars ( 112 , 212 ) in the slot ( 111 , 211 ) concerned.
12 . An active magnetic bearing according to claim 8 , wherein said solid bearing bars ( 112 , 212 ) have a cross-sectional area of at least 5 mm 2 .
13 . An active magnetic bearing according to claim 8 , wherein said solid bearing bars ( 112 , 212 ) are insulated only by being spaced from other elements of said active magnetic bearing by said spacers ( 113 , 213 ).
14 . An active magnetic bearing according to claim 8 , for use in a canned flow machine, said active magnetic bearing comprising the can ( 18 ), separating a working fluid area, from a dry area containing the stator ( 110 , 210 ), with the rotor ( 108 , 208 ) arranged in the working fluid area, said rotor ( 108 , 208 ) being contained in a containment shell ( 117 , 217 ) for protecting the rotor ( 108 , 208 ) from the working fluid.
15 . An active magnetic bearing according to claim 14 , wherein said active magnetic bearing has a clearance ( 20 ) between said rotor ( 108 , 208 ) and said stator ( 110 , 210 ), between said can ( 18 ) and said containment shell ( 117 , 217 ) and said active magnetic bearing is configured to be cooled by a flow of working fluid through said clearance ( 20 ).