The document discusses steam condensers, their functions, classifications, and operational principles, emphasizing their role in maximizing turbine efficiency by creating a vacuum and condensing exhaust steam. It also explains cooling towers used in power and refrigeration plants to cool water from condensers, the mechanics of water cooling, and various types of cooling towers based on draught and materials. Key factors affecting cooling performance, as well as air leakage concerns in condensers, are highlighted to illustrate the importance of maintaining low pressure and efficient operation.

1. Steam Condenser

2. CONDENSER
• The main purposes of the condenser are to condense the exhaust steam
from the turbine for reuse in the cycle and to maximize turbine efficiency by
maintaining proper vacuum.
• As the operating pressure of the condenser is lowered (vacuum is
increased), the enthalpy drop of the expanding steam in the turbine will also
increase.
• This will increase the amount of available work from the turbine (electrical
output).
• By lowering the condenser operating pressure, the following will occur:
• Increased turbine output
• Increased plant efficiency
• Reduced steam flow (for a given plant output)
It is therefore very advantageous to operate the condenser at the lowest
possible pressure (highest vacuum).

3. FUNCTION OF CONDENSER
• Function of the condenser is to create a vacuum by condensing steam,
Removing dissolved non condensable gases from the condensate.
• Conserving the condensate for re-use as the feed water supply to the
steam generator.
• Providing a leak-tight barrier between the high grade condensate
contained within the shell and the untreated cooling water.
• Providing a leak-tight barrier against air ingress, preventing excess back
pressure on the turbine.
• Serving as a drain receptacle, receiving vapor and condensate from
various other plant heat exchangers, steam dumps, and turbine bleed-
offs.

4. Classification of Condensers

5. Classification of Condensers
1. Jet condensers
2. Surface condenser
• Jet Condensers: The exhaust steam and water come in
direct contact with each other and temperature of the
condensate is the same as that of cooling water leaving
the condenser. The cooling water is usually sprayed into
the exhaust steam to cause, rapid condensation.
• Surface Condensers: The exhaust steam and water do
not come into direct contact. The steam passes over the
outer surface of tubes through which a supply of cooling
water is maintained.

6. PARALLEL-FIOW TYPE OF JET CONDENSER:
• The exhaust steam and
cooling water find their
entry at the top of the
condenser and then
flow downwards and
condensate and water
are finally collected at
the bottom.

7. LOW LEVEL JET CONDENSER (COUNTER-FLOW TYPE JET
CONDENSER):
• The steam and cooling
water enter the
condenser from
opposite directions.
Generally, the exhaust
steam travels in upward
direction and meets the
cooling water which
flows downwards.

8. HIGH LEVEL JET CONDENSER (COUNTER-FLOW TYPE JET CONDENSER)
• It is also called barometric
condenser. In this type the
shell is placed at a height
about 10.363 meters above
hot well and thus the
necessity of providing an
extraction pump can be
obviated. However
provision of own injection
pump has to be made if
water under pressure is not
available.

9. EJECTOR FLOW TYPE JET CONDENSER
• Here the exhaust steam and cooling water
mix in hollow truncated cones. Due to this
decreased pressure exhaust steam along with
associated air is drawn through the truncated
cones and finally lead to diverging cone.
• In the diverging cone, a portion of kinetic
energy gets converted into pressure energy
which is more than the atmospheric so that
condensate consisting of condensed steam,
cooling water and air is discharged into the
hot well.
• The exhaust steam inlet is provided with a
non-return valve which does not allow the
water from hot well to rush back to the
engine in case a failure of cooling water
supply to condenser.

10. SURFACE CONDENSOR

11. SURFACE CONDENSERS
DOWN-FLOW TYPE:
• The cooling water enters the
shell at the lower half section
and after traveling through
the upper half section comes
out through the outlet.
• The exhaust steam entering
shell from the top flows down
over the tubes and gets
condensed and is finally
removed by an extraction
pump.
• Due to the fact that steam
flows in a direction right angle
to the direction of flow of
water, it is also called cross-
surface condenser.

12. SURFACE CONDENSERS
CENTRAL FLOW TYPE:
• In this type of condenser, the
suction pipe of the air
extraction pump is located in
the centre of the tubes which
results in radial flow of the
steam.
• The better contact between
the outer surface of the tubes
and steam is ensured, due to
large passages the pressure
drop of steam is reduced.

13. SURFACE CONDENSERS
INVERTED FLOW TYPE:
• This type of condenser has the air suction at
the top, the steam after entering at the
bottom rises up and then again flows down to
the bottom of the condenser, by following a
path near the outer surface of the condenser.
The condensate extraction pump is at the
bottom.

14. SURFACE CONDENSERS
EVAPORATIVE TYPE:
• The principle of this condenser is that when a
limited quantity of water is available, its
quantity needed to condense the steam can
be reduced by causing the circulating water to
evaporate under a small partial pressure.
• The exhaust steam enters at the top through
gilled pipes. The water pump sprays water on
the pipes and descending water condenses the
steam.
• The water which is not evaporated falls into
the open tank (cooling pond) under the
condenser from which it can be drawn by
circulating water pump and used over again.
• The evaporative condenser is placed in open
air and finds its application in small size plants.

15. CONDENSER OPERATION
• The main heat transfer mechanisms in a surface condenser are the condensing of
saturated steam on the outside of the tubes and the heating of the circulating water
inside the tubes.
• Thus for a given circulating water flow rate, the water inlet temperature to the
condenser determines the operating pressure of the condenser.
• As this temperature is decreased, the condenser pressure will also decrease. As
described above, this decrease in the pressure will increase the plant output and
efficiency.
• Due to the fact that a surface condenser operates under vacuum, non condensable
gases will migrate towards the condenser.
• The non condensable gases consist of mostly air that has leaked into the cycle from
components that are operating below atmospheric pressure (like the condenser).
• These gases can also result from caused by the decomposition of water into oxygen and
hydrogen by thermal or chemical reactions. These gases must be vented from the
condenser .

16. SOURCES OF AIR IN LEAKAGE IN A CONDENSER:
• Atmospheric relief valves or vacuum breakers
• Rupture disks
• Drains that pass through the condenser
• Turbine seals
• Turbine instrumentation lines
• Turbine/condenser expansion joint
• Tube sheet to shell joints
• Air-removal suction components
• Penetrations
• Condenser instrumentation, sight glasses, etc.
• Low-pressure feed water heaters, associated piping, valves and instruments
• Valve stems, piping flanges, orifice flanges
• Manhole
• Shell welds
• Condensate pump seals

17. REASON FOR REMOVING AIR/GAS
• The gases will increase the operating pressure of the condenser.
• Since the total pressure of the condenser will be the sum of partial pressures of
the steam and the gases, as more gas is leaked into the system, the condenser
pressure will rise.
• This rise in pressure will decrease the turbine output and efficiency.
• The gases will blanket the outer surface of the tubes. This will severely decrease
the heat transfer of the steam to the circulating water. Again, the pressure in
the condenser will increase.
• The corrosiveness of the condensate in the condenser increases as the oxygen
content increases. Oxygen causes corrosion, mostly in the steam generator.
Thus, these gases must be removed in order to extend the life of cycle
components.

18. COOLING TOWERS

19. COOLING TOWER
• The cooling towers are used in many applications in engineering. The main
application are in power plants and refrigeration plants.
• Its function is to cool the hot water from the condenser by exposing it to
the atmospheric air, so that the cold water may be used again for
circulation.
• The cooling towers are used in steam power plants where there is a
limited supply of cooling water.
• It is placed at a certain height (at about 9 metres from the ground level).
• The hot water falls down in radial sprays from a height and the
atmospheric air enters from the base of tower.
• The partial evaporation of water takes place which reduces the
temperature of circulating water.
• This cooled water is collected in the pond at the base of the tower and
pumped into the condenser.

20. Factors Affecting the cooling of water in a cooling tower
• Size and height of cooling tower,
• Arrangement of plates in cooling tower,
• Velocity of air entering the cooling tower,
• Temperature of air,
• Humidity of air, and
• Accessibility of air to all parts of cooling tower.

21. Types of Cooling Towers
1. According to the type of draught
a) Natural draught cooling towers
b) Mechanical Draught Cooling Towers
i)Forced draught cooling towers, and
ii)Induced draught cooling towers
2. According to the material used
a)Timber cooling tower
b) Concrete (ferro-concrete, multideck
concrete hyperbolic) cooling towers, and
c) Steel duct type cooling tower

22. a)Natural draught cooling tower
• In a natural draught
cooling tower, as shown in
fig., the circulation of air is
produced by the pressure
difference of air inside and
outside the cooling tower.
• In this type of tower, the
hot water from the
condenser is pumped to
the troughs and nozzles
situated near the bottom.

23. b)Mechanical Draught Cooling Towers
• In these towers the draught of air for cooling
the tower is produced mechanically by means
of propeller fans.
• These towers are usually built in cells or units,
the capacity depending upon the number of
cells used.

24. i)Forced draught cooling tower
• In Forced draught
cooling tower, as shown
in fig, the circulation of
air is produced by
means of fans placed at
the base of the tower.

25. ii)Induced draught cooling tower
• In an Induced draught
cooling tower, as shown
in fig, the circulation of
air is provided by means
of fans placed at the top
of the tower.

26. 2. According to the material used
a)Timber cooling tower are rarely used due to the following
disadvantages:
(i) Short life (ii) High maintenance charges (iii)Limited
cooling capacity (iv) Design generally does not facilitate
proper circulation of air.
b) Concrete (ferro-concrete, multideck concrete hyperbolic)
cooling towers, has the following advantages :
(i) Large capacity (ii) Improved draught and air circulation (iii)
Increased stability under pressure (iv) Low maintenance.
c)Steel duct type cooling tower are rarely used in case of
modern power plant due to their small capacity.