Arrangement for cooling the rotor of an electric machine, especially a turbine type generator

Apparatus for cooling the rotor of an electric machine having a superconducting field winding longitudinally disposed thereon comprising:

• (a) a first cold shield exteriorly disposed on and co-rotating with the rotor;
• (b) a mixing chamber interiorly and concentrically disposed on and co-rotating with said rotor;
• (c) a coolant unit supplying coolant at a low temperature and receiving coolant at a relatively higher temperature;
• (d) means for injecting a phase mixture of said coolant of said coolant unit into said mixing chamber via a coolant injecting line;
• (e) a first coolant line for a first coolant stream of liquid coolant derived from said coolant phase mixture;
• (f) said first coolant line comprising at least one winding feed line radially disposed at one end of said rotor and in communication with said mixing chamber;
• further a plurality of winding cooling canals interiorly disposed on said rotor and in heat transfer contact with said superconducting field winding, said winding cooling canals being in communication with said winding feed line;
• and at least one winding discharge line in communication with said winding cooling canals, radially disposed at the other end of said rotor and in communication with said mixing chamber for conducting at least a part of the first coolant stream into said mixing chamber;
• (g) a second coolant line for a second coolant stream having at least partly evaporated coolant derived from said coolant phase mixture;
• (h) said second coolant line comprising at least one cold shield feed line radially disposed at one end of said rotor and in communication with the radially inner part of the mixing chamber, further at least one cold shield cooling canal in communication with said cold shield feed line said shield cooling canal axially disposed in heat transfer contact with said cold shield;
• and at least one cold shield discharge line radially disposed at the other end of said rotor, said cold shield discharge line in communication with the input of said coolant unit and said cold shield cooling canal;
• (i) a connecting line in communication with said winding discharge line of the first coolant stream and with the cold shield feed or discharge line of the second coolant stream for admixing a coolant substream derived from said first coolant stream after said first coolant stream has passed through said field winding with said second coolant stream;
• and
• (j) a throttling device incorporated within said connecting line whereby the amont of additional coolant fed of the coolant substream into said second coolant stream can be controlled.