HYDROGEN COOLED GENERATOR
All large steam turbine-driven generators in power plants operate in an enclosure, or casing, that is pressurized at 20 to 80 PSIG with pure Hydrogen. Why??
Hydrogen gas has the highest thermal conductivity and heat removal capacity of any known gas. Hydrogen also has the lowest density and therfore has the lowest "windage" losses (the rotating parts turn with the least friction). It's a supurb coolant for the purpose. Fans that turn with the shaft circulate the hydrogen throughout the generator. Typically the heated hydrogen is cooled by water "radiators" that are in the circulation path.
As an additional benefit, hydrogen gas minimizes "corona" discharge (which degrades the insulation) that can surround high-voltage windings in air.
Since the hydrogen used is 99% pure, there it no risk of internal fire or explosion, unless the gas becomes contaminated with air.
Hydrogen cooling permits the manufacturer to increase the energy density (kilowatts per cubic foot) over that of air-cooled generators, as well as increase efficiency. Modern hydrogen-cooled generators are the most efficient man-made machines on the planet, converting 99% or more of the mechanical horsepower into kilowatts.
The generator's shaft must pass out of the pressurized casing to couple to the steam turbine (or other Prime Mover). Close-fitting liquid oil fed rings around the shaft provide a zero-leakage seal for the shaft penetration through the casing.
Even higher energy densities (more kilowatts per cubic foot) can be produced if the stationary windings are additionally liquid-cooled. Hydrogen is STILL used as a cooling gas in liquid-cooled machines. This photo shows a hydrogen-cooled machine (no liquid cooling).
A 3D Stereo Crosseye view.
TO SEE THIS IN 3D, there's a tutorial here:
HYDROGEN COOLED GENERATOR
All large steam turbine-driven generators in power plants operate in an enclosure, or casing, that is pressurized at 20 to 80 PSIG with pure Hydrogen. Why??
Hydrogen gas has the highest thermal conductivity and heat removal capacity of any known gas. Hydrogen also has the lowest density and therfore has the lowest "windage" losses (the rotating parts turn with the least friction). It's a supurb coolant for the purpose. Fans that turn with the shaft circulate the hydrogen throughout the generator. Typically the heated hydrogen is cooled by water "radiators" that are in the circulation path.
As an additional benefit, hydrogen gas minimizes "corona" discharge (which degrades the insulation) that can surround high-voltage windings in air.
Since the hydrogen used is 99% pure, there it no risk of internal fire or explosion, unless the gas becomes contaminated with air.
Hydrogen cooling permits the manufacturer to increase the energy density (kilowatts per cubic foot) over that of air-cooled generators, as well as increase efficiency. Modern hydrogen-cooled generators are the most efficient man-made machines on the planet, converting 99% or more of the mechanical horsepower into kilowatts.
The generator's shaft must pass out of the pressurized casing to couple to the steam turbine (or other Prime Mover). Close-fitting liquid oil fed rings around the shaft provide a zero-leakage seal for the shaft penetration through the casing.
Even higher energy densities (more kilowatts per cubic foot) can be produced if the stationary windings are additionally liquid-cooled. Hydrogen is STILL used as a cooling gas in liquid-cooled machines. This photo shows a hydrogen-cooled machine (no liquid cooling).
A 3D Stereo Crosseye view.
TO SEE THIS IN 3D, there's a tutorial here: