1. MODULE 5

2. CONDENSERS FUNCTION
• Condensers are used to convert a vapor back
to a liquid. Condensers are found on larger
turbines used for power generation or process
systems

3. TYPICAL CONDENSER
• Made up of four main parts
1. The shell
2. The tube sheets
3. The water boxes
4. The tubes.
The shell is the main part of the condenser’s structure.
Condensers are used to convert vapor back into liquid.
The flow path of water is referred to as the tube side
of the condenser. The path of the steam on the
outside of the tubes is called the shell side

6. PARTS OF THE CONDENSING UNIT
1.Condensing unit fan motor BLADE ASSEMBLY.
2.Condenser FAN MOTOR.
3.Fan motor MOUNTING BRACKET.
4.CAPACITOR to assist motors in running more efficiently.
5.CONTACTOR (the relay that allows the 230 VAC to turn on the motors.
6.CONDENSER COILS (refrigerant runs through the tubes and ambient
air is pulled through the fins to cool the hot gas).
7.SUCTION LINE VALVE that closes the refrigerant flow and/or gives a
port in which to attach the pressure gages and hoses.
8.LIQUID LINE VALVE to close off the high pressure and/or provides an
access port for pressure measurement.
9.COMPRESSOR MOUNTING BASE.
10.COMPRESSOR motor and pump. The newest compressor is the
SCROLL, a giant step forward in efficiency.

7. • As, the hot vapor passes over the tubes, it
gives up heat and condenses back into liquid,
which collects at the bottom of the shell side
area. This area is called the hotwell.

8. OPERATION:
• Steam flows down through the shell of the condenser
over the bundle of tubes.
• The steam’s heat is given up to the cold water flowing
through the tubes. The steam gives up its heat until it
reaches its saturation temperature – the point at
which it condenses into water. Droplets of liquid then
form on the tubes and fall down through the drain at
the bottom of the condenser and into the hotwell at
the bottom of the shell.
• The main condenser for a larger steam turbine is
typically installed suspended directly below the turbine

10. Low level condenser

11. Barometric condensor

12. Jet condensor

13. • Steam exhausts from the turbine straight
done into the condenser shell and passes over
the tube bundle.
• When the water reaches the far end of the
water box, it flows up and back through the
upper tube bundle to the outlet water box.
The water flows out from there, and
eventually returns to the body of water from
which it came.

14. TYPES OF CONDENSERS
Condensers are classified as
1. SURFACE CONDENSER
2. JET CONDENSER
In surface condenser, the steam to be
condensed is usually passed over a large
number of tubes through which cooling water is
passing. The steam is condensed on the surface
of the tubes as it gives up its enthalpy to the
cooling water passing through the tubes

15. • In jet condenser, the steam to be condensed
comes into direct contact with the cooling water
which is usually introduced in the form of a spray
from a jet.
• Both types of condenser may be operated as
either a wet or dry condenser.
• In wet condenser, any gas which does not
dissolve in the condenser is removed by the same
pump which is dealing with the condensate.

16. • In dry condenser, the free gas and the
condensate are removed separately.
• A further division in condensers is possible being
a function of the relative directions of flow of
the condensing steam and the cooling water
• The three possibilities are:
1. Transverse flow in which the steam flows across
the path of the cooling water.
2. Parallel flow in which the steam flow is in the
same direction as the cool water.

17. 3. Counter flow (contra flow), in which the
steam flows in the opposite direction to the
cooling water.
Still further division of the condensers is
possible :
1.The barometric condenser: the principle of
operation is illustrated in the fig

18. • The condenser here is mounted on along pipe which is
usually at least 10.34m long .The pipe, called the
barometric leg, acts in every similar way to a
barometer. If the water was used in a barometer then
the barometer height would be about 10.34m.
• If however, instead of a Toricellian vacuum existing on
the top of the water in the pipe, there exists some
positive pressure, less than atmospheric such as in the
case of a condenser, then the height of water column
will be less than 10.34m, being a function of the
degree of vacuum which exists.

19. • This is illustrated as h in the fig. Using this
atmospheric leg it is possible, in the
condenser, for the condensate to drain away
by gravity into the atmospheric tank at the
bottom. The atmospheric leg dips deeply into
the water in the atmospheric tank. The
discharge from the atmospheric tank is from a
stand pipe, whose entry is high up maintaining
a constant high level discharge. In this way
there is no possibility of breaking the vacuum
in the condenser.

20. 2.THE LOW LEVEL CONDENSER
• The condensate is removed by means of
pump. Its installation is appropriate when
there is not enough height available for the
installation of a barometric condenser.
• Figure illustrates a transverse flow surface
condenser. Steam is admitted to the top of
the condenser and is removed as condensate
from the bottom having been condensed at
the surface of the water tubes. Cooling water
flows in at the bottom and out at the top of
the condenser.

21. • Inlet and exit in this case are both at the same
end of the condenser and hence the water
makes two passes through the condenser.
• The condenser illustrated is a dry condenser
since air and condensate are extracted
separately.

22. JET CONDENSER
• It consists of a tall cylinder into which are
introduced perforated baffle plates. They are
fixed alternatively on either side of the
cylinder and cover just over half the cross-
sectional area of the cylinder. Cooling water is
introduced, in the form of a spray at the top of
the condenser. Steam is introduced at the
bottom of the condenser.

23. • Due to its low density it will begin to rise up in
the condenser and the spray and condensate
will fall together to the bottom of the
condenser and will be extracted. Air entering
the condenser will be warm and hence will
rise to the top and from here it is extracted.

24. • This condenser is of the dry type since both air
and condensate are extracted separately. The
steam and cooling water move in opposite
directions through the condenser and hence
this is a counter flow condenser

25. SAFETY PRECAUTIONS
• Safety precautions are taken to prevent
potential harm to the maintenance personnel.
• The first of these is to shutdown the cooling
water system of which the condenser is a part.
Most condensers have their water sides
divided into two separate sections. Each half
can be taken out of service, one at a time,
with the turbine still in operation at reduced
capacity. The cooling water to one half will be
shut off while the other half is still running.

26. • The valves and pumps are then tagged out of
service.
• The next step is to open the condenser and
perform an air quality check. The air in the
condenser is checked to make sure that there
is enough oxygen to support life and that
there are no poisonous or explosive gases
present.

27. • Low voltage safety lighting is provided to
prevent the hazard of shock to personnel. As
in any confined space, the two-man rule is
followed- a helper keeps watch from outside
to ensure the safety of the worker who goes
inside

28. SERVICING CONDENSERS
• There are three routine maintenance
procedures that are usually done:
1.The water boxes are cleaned out and the
tube sheets scraped or brushed clean.
2.The tubes are cleaned of any blockage or
buildup, and
3.Any leaking tubes are found and plugged.
Clearing the tubes is often done by a method
called shooting them.

29. • Shooting the tubes involved the use of special
water gun. This procedure may be done with
high pressure water, water and compressed
air, rubber squeezees, brushes or metal
bladed scrapers. When the tubes are cleared,
it is easier to detect leaking tubes that must
be plugged.

30. • To seal leaks while the condenser is on line,
any of several substances can be introduced
into the cooling water before it goes through
the tubes. The substances must be bio
degradable to prevent any danger to the
environment when water flows back out.
• One of the substances used is sawdust. The
use of sawdust to plug leaks is one example of
an ingenious stop-gap.

31. CONDENSATION PROCESS
• The vapor starts condensing on a surface
when the vapor saturation temperature is
more than the surface temperature. The
temperature of the condensate formed on the
surface is less than its saturation temperature
and it becomes sub-cooled, more vapor will
condensate on the exposed surface or on the
previously formed condensate as the
temperature of the previous condensate is
less than the saturation temperature of vapor

32. TYPES OF CONDENSATION
PROCESSES
• Film condensation -the condensate tends to
wet the surface , forming a liquid film. The
heat from the vapor to the cooling medium is
transferred through the film condensate
formed on the surface.
• Dropwise condensation- the condensate
forms droplets on the surface and every time
fresh surface is exposed to the vapor.

33. • In dropwise condensation only a part of the
surface is covered with condensate. Very high
heat transfer rates are reported due to good
contact between the vapor and surface.

34. THEORY OF LAMINAR FILM
CONDENSATION
• Most condensation encountered in actual
equipment are film wise in character.
• The physical nature of the laminar film
condensation process is well understood.
Nusselt described the process in 1916 and
analyzed condensation process occuring
under several different geometric and vapor
velocity conditions.

35. NUSSELT’S THEORY OF LAMINAR
FILM CONDENSATION
• The following assumptions are made for
derivation.
• The liquid film is in good thermal contact with
the cooling surface and therefore it is
assumed that the inside film face has the
temperature of the cooling surface.
• The flow of liquid film formed on the surface
remains in laminar region.
• Viscous shear of vapor on the liquid film is
negligible at the boundary.

36. • Linear temperature distribution exists
between wall and vapor
• The properties of liquid film as ρ, K μ, and Cp
are constant throughout the liquid film
• The latent heat of condensation at the liquid
and vapor interface is carried by conduction
through the liquid film along y- direction.
• The velocity of liquid film formed along y-
direction is zero.

37. • Assuming the vapour is condensing on a flat
vertical wall as
• Ts= saturation temperature of the steam
• Tw = temperature of the wall
• ρ=density of liquid film
• μ=absolute viscosity of condensing liquid.
• hfg= latent heat of vapour
• K=conductivity of liquid

38. X=length measured from the starting point of the film
g=acceleration due to gravity.
If the vertical height of the plate is L, then the average heat
transfer coefficient is given by,

39. Drop wise condensation:
when saturated pure vapor comes into contact with a cold
surface such as tube, it condensate and form liquid droplet on
the surface of the tube, they fall from it leaving bare metal on
which successive droplet of condensate may form. When
condensate occur by this mechanism ,it is called drop wise
condensation.
A considerable amount of attention has been given to the drop
wise condensation process because it gives heat transfer rate
ten to twenty times as great as that for film wise condensation.
Film wise condensation is one in which condensation will occur
in the form of a thin film

40. Effect of air(or other gases) in
condensor
A very small air leak into the condensing system of steam power
plant will have a far more effect on efficiency , than that cause
by partial pressure of the air. In fact all condensing vapor heat
exchanger perform much better when all non condensable
gases are eliminated.