FIELD OF INVENTION
The invention relates to an improved sealing device for vertical type generator
air coolers adaptable to thermal power plant.
BACKGROUND OF INVENTION
Generator air coolers are mounted vertically by the side of the generator used in
thermal power plants. The Generator air cooler is a heat exchanger in which
cooling water flows through tubes and air flows over (outside) the tubes. The hot
air coming from generator windings is cooled by the cold water and the cooled
air is again recirculated into the generator for cooling the generator windings.
When the waterside gasket leaks, the water enters into the cooler enclosure and
finally enter into the generator windings. As the leakage water enters, moisture
content in the generator windings rises and shown on the moisture indicator.
Whenever water leaks and enters the generator windings, the generator has to
be shut down. After shutdown, the cooler element has to be lifted up and the
bottom water box has to be dismantled. Then the leaking gasket needs to be
attended/replaced. After replacement of the leaking gasket, the heat exchanger
has to be hydro tested. This process requires 36-hour shutdown. This kind of
shutdown causes huge loss of power generation.

OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved sealing device to
prevent leaking water from entering into generator winding.
Another object of the invention is to propose an improved sealing device which reduces
the frequency of generator shutdown.
A further object of the invention is to propose an improved sealing device which
improves the economics of power generation.
SUMMARY OF INVENTION
The present invention is provided with sealing arrangement of air cooler for vertical
tube generator in thermal power plant, the device comprising a tube sheet provided on
the gasket sealing surface of a water box flange, the water box flange resting on the
generator duct, a gasket disposed on the sealing surface and at least one water box
connected to the water box flange being disposed downwardly characterized in that the
tube sheet is provided with "T" shape outlined at both ends such that the gasket sealing
surface and the water box flange remain disposed outside of the generator duct to
prevent entry of leaking water into the generator windings.
Thus, according to the invention, a step is provided on the bottom tube sheet. With this
new configuration, the bottom tube sheet step now rests on the frame of the duct. The
water box is taken outside the duct opening along with the gasket sealing arrangement.
The tube layout is correspondingly modified.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - shows a sealing arrangement of vertical type generator air coolers
according to prior art.
Figure 2 - schematically shows an improved sealing device of vertical typed
generator air coolers according to the invention.
DETAILED DESCRIPTION OF INVENTION
In prior art arrangement shown in Figure 1, the sealing was done with backside
of water box flange (1) resting on the generator duct (2). As the gasket sealing
surface (4) was above the duct (2), leaky water always enter into the generator.
As the water enters, the moisture content in the generator windings rises and
leads to shut down of the generator. After shutdown, the cooler element has to
be lifted up and the bottom water box (5) has to be dismantled. Then the leaking
gasket (4) needs to be attended/replaced. After replacement of the leaking
gasket (4), the heat exchanger has to be hydro tested. This process requires 36-
hour shutdown. This kind of shutdown causes huge loss of power generation.
As shown in figure 2, the improved sealing device comprises tube sheet (6)
having step-like configuration at both ends which lowers the gasket sealing
surface (4) and the water box flange (1) outside the duct (2). This arrangement
always ensures that the leaky water falls outside the duct (2) and hence

prevents the entry of water into the generator. The improved sealing device
eliminates frequent shut down of the generator. With this modified arrangement,
the leaking water will not enter into generator windings and can be attended
without shut down of the generator.

WE CLAIM
1. Sealing arrangement of air cooler for vertical tube generator in thermal power
plant, the device comprising:
- a tube sheet (6) provided on the gasket sealing surface of a water box flange
(1), the water box flange (1) resting on the generator duct (2), a gasket (4)
disposed on the sealing surface;
- at least one water box (5) connected to the water box flange (1) being disposed
downwardly;
characterised in that the tube sheet (6) is provided with "T" shape outlined at
both ends such that the gasket sealing surface and the water box flange (1)
remain disposed outside of the generator duct (2) to prevent entry of leaking
water into the generator windings.
2. Sealing arrangement of air cooler for vertical tube generator in thermal power
plant as substantially herein described and illustrated with the accompanying
drawings.

The invention relates to sealing arrangement of air cooler for vertical tube generator in
thermal power plant, the device comprising a tube sheet (6) provided on the gasket
sealing surface of a water box flange (1), the water box flange (1) resting on the
generator duct (2), a gasket (4) disposed on the sealing surface and at least one water
box (5) connected to the water box flange (1) being disposed downwardly
characterised in that the tube sheet (6) is provided with "T" shape outlined at both ends
such that the gasket sealing surface and the water box flange (1) remain disposed
outside of the generator duct 92) to prevent entry of leaking water into the generator
windings.