Shaft seal assembly for hydrogen cooled turbine generator

1. A seal assembly forming a seal with a rotatable shaft of a hydrogen-cooled generator, the seal assembly comprising:

a ring assembly disposed about the rotatable shaft and including a fluid inlet and a fluid outlet, said ring assembly comprising:

a hydrogen side ring directly coupled to a generator frame of the generator;

an insulating structure positioned between said hydrogen side ring and said generator frame to provide electrical insulation between said hydrogen side ring and said generator frame;

an air side ring disposed adjacent to said hydrogen side ring;

seal structure coupled to said air side ring; and

structure for supplying oil to said ring assembly such that the oil flows through said ring assembly to an interface between the rotatable shaft and said seal structure so as to substantially limit direct contact between the rotatable shaft and said seal structure.

2. A seal assembly as laid out in claim 1 , wherein said air side ring is mechanically coupled to said hydrogen side ring.

3. A seal assembly as laid out in claim 1 , wherein said fluid inlet is formed in said air side ring and in communication with a seal oil pump that conveys substantially clean oil to said fluid inlet.

4. A seal assembly as laid out in claim 1 , wherein said generator frame comprises an end shield and at least one insulated fastening structure is used to mount said hydrogen side ring to said end shield.

5. A seal assembly as laid out in claim 1 , wherein said hydrogen side ring and said air side ring are formed from segments of carbon steel.

6. A seal assembly as laid out in claim 1 , wherein said seal structure comprises carbon seal segments that are arranged on said air side ring to extend about the rotatable shaft.

7. A seal assembly as laid out in claim 1 , wherein said insulating structure comprises a gasket formed from one of paper, rubber, and silicon.

8. A seal assembly forming a seal with a rotatable shaft of a hydrogen-cooled generator, the seal assembly comprising:

a ring assembly disposed about the rotatable shaft and including a fluid inlet and a fluid outlet, said ring assembly comprising:

a first side ring directly coupled to a generator frame of the generator;

an insulating structure positioned between said first side ring and said generator frame to provide electrical insulation between said first side ring and said generator frame;

a second side ring coupled to said first side ring, wherein said second side ring is not in direct contact with said generator frame;

seal structure coupled to one of said first and second side ring; and

structure for supplying oil to said ring assembly, such that the oil flows through said ring assembly to an interface between the rotatable shaft and said seal structure so as to substantially limit direct contact between the rotatable shaft and said seal structure.

9. A seal assembly as laid out in claim 8 , wherein said fluid inlet is in communication with a seal oil pump that conveys substantially clean oil to said fluid inlet.

10. A seal assembly as laid out in claim 8 , wherein said generator frame comprises an end shield and at least one insulated fastening structure is used to mount said first side ring to said end shield.

11. A seal assembly as laid out in claim 8 , wherein said first side ring and said second side ring are formed from segments of carbon steel.

12. A seal assembly as laid out in claim 8 , wherein said seal structure comprises carbon seal segments that extend about the rotatable shaft.

13. A seal assembly as laid out in claim 8 , wherein said insulating structure comprises a gasket formed from one of paper, rubber, and silicon.