Condensation in air cooler generator

[yulinios]

Hi there

In a hydraulic power plant: Toshiba Generator of 48.2 MVA, Stator and Rotor insulation class F, which is air cooled, there are 4 coolers plate fin type fixed with tube sheets, the circulation of air is performed by mean of rim duct equipped on the generator rotor, the cooling system was designed to operate only with 3 coolers, with p.f. 09, and aging factor of 1.1.

There is a condensation problem in the tube sheets of the coolers, condensate water reach the floor (water box is not enough in large), we think that is very risky that water could reach the stator (vertical position) so we are drying the floor with wipes permanently by now.

Humidity has been increased by rains, relative humidity now is 55 – 60 %, dew point is 19 - 21°C , the water inlet temperature is 14 °C (cooler design: 25°C), we are decreasing the flow from 40 to 24 L/seg, condensation has decreased but the generator stator temperatures have increased in 4°C (from 84 to 88°C).

Are there some problem to operate the generator with 4°C more?

Thanks, bye there!

 

[EdStainless]

You don't really want to choke the flow to do this. Can you install a pump and recirculation line to take some of the water back through the system? This would let you stay above the dewpoint.
What is your design stator temp? Higher temps are never good, but if you are still below the design then you should be safe.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

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[metengr]

Check with the generator OEM (Toshiba) regarding your problem.

 

[yulinios]

Edstainless and Metengr

Is good idea to recirculate the water, but we're thinking to put a close cooling water system or use the water oulet to cool another one, actually the cws is open and the water from the river have solids, we are trying to adjust flows to reduce pumping energy and to eliminate condensation with partially good results.

Generator plate says "Increase Temperature: 80 °C", so we are safe. Toshiba OEM says 40°C air oulet (actually: 27-29 °C) and for water 25 °C (actually: 14°C).

Bye there!

 

[EdStainless]

I can give you a number of reasons to build a secodnary cooling water loop.
Keeping sand, silt, and live creatures (small and large) out of your coolers are the biggest reasons.


= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm