Alternator (generator) shaftsealsystem

That's a complicated word for a complicated system.

This is one of the most important systems in each unit of the plant, also in EC 20.

It's the shaft seal system of the generator and it's purpose is to keep the coolant (hydrogen) inside the generator.
It comprises of a set of pumps (one main pump and two back-ups), a few dearator tanks, regulating valves, vacuumpumps (to maintain a slight vacuum in the dearating tanks to get the hydrogen out of the oil) and the special labyrinth seals in the generator.

It's far to complicated to explain it all but we use hydrogen as a coolant because it cools a lot better than air and thus the generator (and it's coolers) can be kept a lot smaller.
Hydrogen is highly explosive in combination with air so this system keeps air and hydrogen apart.

Why a picture of this system today?
Well, a collegue stated one valve in the system was in the wrong position (for 15 years!!).
But the operation notice of the manufacturer said it had to be like we operate it.
We spent quite some time to sort it all out because we became in doubt... but in the end we figured out it is in this position because the oil has to be cooled by the main oil system....
When we shut the valve the oil becomes overheated.
It's that simple....

The big tank is one of the dearator tanks and for buffering part of the oil.
It has an automatic level regulator.

Here in LARGE....