FIELD OF THE INVENTION
The invention relates to a turbo generator used in a power
plant for utility or industrial application. The invention in
particular relates to a method of replacing a generator cooler in
an operating mode of the pouter plant.
BACKGROUND OF THE INVENTION
Hot air from generator is allowed to flow across the coolers
where the air gives away its heat to the coolers (heat
exchangers). Cooling water is continuously circulated through the
heat exchangers * which becomes hot due to heat absorption and
this is let out to the chillers.
As per prior art) the generator is taken for a shut down, in
the event one of the coalers is proposed to be replaced or
repaired. Shut down is necessary as otherwise, almost entire
volume of generator hot air will pass through the gap created
from the removal of one of the coolers. This will make the
machine ventilation ineffective. In view the above, it warrants
machine shut down, when it is planned for cooler
replacement/repair.
Heat generated in a turbo-generator during power generation
is dissipated by circulating cold air into the machine. As the
size of the machine increases, in particular for generators
employed in industrial and utility units* a separate ventilation
system is improved to continuously dissipate heat. The
ventilation system employed is either a closed circuit or an open
circuit system. The closed circuit system envisages channeling
the hot air across the air to water heat exchangers (coolers)*
mounted in a separate cooler duct and return the cold air into
the machine. Axial flow fans mounted on the generator rotor
develop the necessary head. The open circuit ventilation system
is used in cases when clean air available at installation site
and the peak ambient temperature doesn't exceed very high values.
The present invention is directed on the closed circuit air
cooling system. The coolers in the system are arranged in a row
while air flow takes place simultaneously across all the coolers
in the circuit.
As per the prior art* the coolers are assembled in a row
without providing any spare cooler in the assembly. A spare
cooler even if provided, the same is stored separately outside
the assembly. Hence as per prior art* it becomes necessary to
take a machine shut down for removing any of the operating or a
defective cooler from the assembly for replacing with a spare
cooler. This leads to loss of time in repair/replacement
including loss of power supply and thus uneconomic.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a
method of replacing a generator cooler in an operation mode of
the power plants.
Another object of the invention is to propose a method of
replacing a generator cooler in an operation mode of the power
plants which eliminates the disadvantages of the prior art.
And yet another object of the invention is to propose a
method of replacing a generator cooler in an operation mode of
the power plants which is economic and easy to unplanat.
SUMMARY OF THE INVENTION
Accordingly* there is provided a method of replacing a
generator cooler in an operation mode of the power plants*
comprising:
— placing a spare cooller in an assembly of a plurality
of operable coolers} and
— introducing a flap element in the hot—air circuit
adjacent to a cooler intended for replacement* the flap
preventing gushing out of air through a space created
by removal of the cooler intended for replacement*
thereby allowing replacement without discontinuing the
operation of the power plant.
Thus* a typical closed circuit air cooling system employed
for an air cooled turbo—generator has a plurality of cooler
elements assembled in a row.
During the operation of a turbo—generator * the heat
generated in the machine is removed with the aid of cold air. The
air thus circulated into the machine becomes hot on absorbing heat
from the generator.
The hot air flows across the coolers and transfer the heat
to the cooler elements. The cold air coming out of the cooler
elements is returned to the generator. Necessary head required
for affecting the air flow is provided by the axial flow fans,
mounted on the generator rotor.
The hot air from the generator is drawn out and circulated
across the cooler elements* through an air duct configured in the
concrete walls. The cooler elements are air to water heat
exchangers which are hung below a supporting structure.
The supporting structure in turn is anchored to the concrete
walls. The hot air flows across the coolers and transfer the heat
to the cooler elements. The cold air coming out across the
coolers is returned to the generator. Necessary head required
for effecting the air flow is provided by the axial flow fans*
mounted on the generator rotor.
The spare cooler element is assembled with other cooler
elements in the same row but is blanked from the circuit by
placing a flap. The flap is a thin sheet made out of mild steel
or aluminum having a handle on one end riveted for facilitating
easy insertion and removal. By using the handle* the flap can be
inserted above any of the assembled row of coolers. When the flap
is there in position* the cooler below a particular cooler can be
removed at any time and used in place of the damaged cooler
element in the circuit. Till the damaged element is repaired and
reinstalled* the flap will prevent air from gushing out through
the space created by the removal of the defective cooler. Thus* a
cooler element can be removed for rectification without stopping
the machine.
As per the invention* one spare element is added to the row
of existing elements. All the coaler elements are provided with
an arrangement that prevents air flow across the element. The
arrangement envisages blanking of any of the desired coolers at
any point of time. The flap is a thin sheet made out of mild
steel or aluminum having a handle on one end works as an
obstruction or as a stopper to stop the air flow across any of
the cooler elements. By using the handle* the flap can be
inserted above any of the assembled row of coolers. When the flap
is there in position, the cooler below the flap can be removed at
any time for repair/replacement with a new cooler. The
arrangement of flap prevents air from gushing out through this
space created by the removal of defective cooler. Thus* a cooler
element can be removed from rectification without stopping the
machine.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - shows a general arrangement of a closed circuit
cooling system according to the prior art.
Figure 'Z — shows a general arrangement of a closed circuit
air cooling system according to the invention* with air flow
paths indicated.
Figure 3 — shows the details of a flap device according to
the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
THE INVENTION
Air cooled turbo generators* employed with a closed circuit
or open circuit ventilation system envisages circulation of air
flow in a closed path. This arrangement ensures supply of clean
air to the generator* a condition necessary to protect the
machine internals. A plurality of axial flow fans are mounted on
the machine to suck cold air (CA) from the coolers <4> and force
the same into the machine. The fans are mounted one set each on
either side of the generator. The cold air (CA)* circulated
through the generator internals* takes away the heat generated
therein and the air becomes hot. The hot air (HA) is brought to
the center of the generator from which it is allowed to flow
across the coolers (4) mounted in the air flow circuit.
A cooler bank which comprises of several cooler elements
(4), placed in a row* is fastened to a frame structure (3) which
in turn is fastened to the concrete walls (2). Replacement is
necessitated either due to the tube leakages or for replacing the
water box partition gaskets. The flap (7) is made out of either
thin steel or aluminum sheets and is introduced above the spare
cooler element (4). A separate slot is made in the support
structure <3)» to insert the flaps <7). Buidee (9) for the flap
<7> facilitate easier insertion of the flap (7).
The guides (9) and slots are made on all the cooler element
(4) locations. Back face (B) of the supporting beam of the flap
<7> is placed adjacent to the flap (7).
The generator stator is supported by a stator frame (4) which
is placed on a bearing device (b).
A concrete slab (1) is configured between the concrete wall
(2) and the bearing device (5).
WE CLAIM:
1. A method of replacing a generator cooler in an
operation mode of the power plants comprising:
— placing a spare cooler in an assembly of a
plurality of operable coolers; and
— introducing a flap element in the hot air circuit
adjacent to a cooler intended for replacement* the
flap preventing gushing out of air through a space
created by removal of the cooler intended for re-
placement! thereby allowing replacement without
discontinuing the operation of the power plant.
2. A method of replacing a generator cooler in an operat-
ion mode of the power plants as substantially described and
illustrated herein with reference to the accompanying
drawings.

The invention relates to a method of replacing a generator
cooler in an operation mode of the power plants, comprising
placing a spare cooler in an assembly of a plurality of operable
coolers; and introducing a flap element in the hot air circuit
adjacent to a cooler intended for replacement, the flap
preventing gushing out of air through a space created by removal
of the cooler intended for replacement, thereby allowing
replacement without discontinuing the operation of the power
plant.