Steam turbine power plant

1. STEAM TURBINE
POWER PLANT
Course Instructor: Md. Tarek Ur Rahman Erin
Sr. Lecturer, MTE, WUB
Course Title: Power Plant Engineering; Course Code : MTE 905
WEEK 04

2. Overview of topics
Steam power plant
Major Components of steam power plant
Boiler
Boiler Mountings
Air Pre heater
Super-heater
Economizer
Re heater
Turbine
Condenser
Feed water pump

3. Elements of a simple steam power plant

4. Steam power plant
A steam power plant
is a power plant in
which
heated,
water is
turns into
steam and spins a
steam turbine which
drives an electrical
generator to
produce electricity.
Fig: Layout of steam powerplant.

5. Major Components of steam power plant

6. Boiler
A boiler is a closed
vessel in which water
or other fluid is heated.
The heated or
vaporized fluid exits the
boiler for use in various
processes or heating
applications.
Two types,
a. Water tube boiler
b. Fire tube boiler

7. Water tube boiler
The water flow
through the tube and
the flow gases flow
outside the tube.

8. Fire tube boiler
The fire tube boiler
in which the flow
gases passes
through the tubes
and water store out
side the tube.

9. Boiler Accessories
Air Pre heater
Air pre heater is a heat
recovery unit . An air pre
heater is used to recover
the heat from the exhaust
flue gas.

10. Boiler Accessories
Air Pre heater
The purpose of the air pre heater is to recover the heat from the boiler
flue gas which increases the thermal efficiency of the boiler by reducing
the useful heat lost in the flue gas.
Fig: Layout of air preheater.
There are two types of air
pre heaters for use in
steam generators
 Tubular type built into the
boiler flue gas ducting
 Regenerative air pre heater

11. Boiler Accessories
Super-heater
A super- heater is a device used to convert
saturated steam or wet steam into dry steam
used in steam engines

12. Boiler Accessories
Super heater
It’s purpose is to increase the temperature of steam without
raising the pressure. It’s generally an integral part of the boiler
Type of Super heater
 A radiant super heater is placed directly in the combustion
chamber.
 A convection super heater is located in the path of the hot
gases.
 A separately fired super heater, as its name implies, is totally
separated from the boiler.

13. Boiler Accessories
Economizer
An economizer is a device
used to heat the feed water and
heat the condensate from
turbines before it is pumped to
the boilers by utilizing the heat
exhaust
leaving
flue gasses
through
in the
before
chimney.
Fig: Layout of Economizer.

14. Boiler Accessories
Economizer
• Economizers are commonly used
as part of a heat recovery steam
generator in a combined cycle
power plant.
• A common application of
economizers in steam power
plants is to capture the waste
heat from boiler stack gases (flue
gas) and transfer it to the boiler
feed water. This raises the
temperature of the boiler feed
water

15. Boiler Accessories
Re-heater

16. Boiler Accessories
Re-heater
 Re-heaters are the same as the super-heaters but the
temperature of it’s a little bite less than super-heaters and
their pressure is 20%- 25% less than the super-heater,
 It usually use to elevate the steam temperature. After
expanding through the high pressure turbine the exhaust
steam is returned to the boiler at 360 C and 42 bar pressure
for reheating before being used in the intermediate pressure
turbine.
 The re-heater reheats the steam from a temperature of 360 C
back to 568 C.

17. Boiler Mountings
Different fittings and devices necessary for the
operation and safety of a boiler are called boiler
mountings. The various boiler mountings are:
1. Water level indicator
2. Pressure gauge
3. Steam stop valve
4. Feed check valve
5. Blow-down cock
6. Fusible plug
7. Safety valve : spring loaded, dead weight, lever
type.

18. Boiler Mountings
Water level indicator
The function of the water level
indicator is to indicate the
level of water in the boiler
constantly. Every boiler is
normally fitted with two water
level indicators.

19. Boiler Mountings
Pressure gauge
 The pressure gauge is used to indicate the
steam pressure of the boiler. The gauge is
normally mounted in the front top of the
steam drum.
 Pressure gauges are connected to the
steam space of the boiler and usually
have a ring type siphon tube which fills
with condensed steam and protects the
dial mechanism from high temperatures.
 The commonly used pressure gauge is the
Bourdon type pressure gauge .

20. Boiler Mountings
Steam Stop Valve
• The function of the stop valve is to regulate the
flow of steam from the boiler to the prime
mover as per requirement and shut off the steam
flow when not required.
• A commonly used steam stop valve is shown in
figure, it consists of main body, valve, valve
seat, but and spindle, which passes through a
gland to prevent leakage of steam. The spindle
is rotated by means of a hand wheel to close or
open.

21. Feed Check Valve
Boiler Mountings
 The function of the
feed check valve is
to allow the supply
of water to the boiler
at high pressure
continuously and to
prevent the back
flow of water from
the boiler when the
pump pressure is less
than boiler pressure.

22. Boiler Mountings
Blow-Down Cock
• The function of blow-down cock is to remove sludge or sediments
collected at the bottom-most point in the water space in a boiler, while the
boiler is steaming.

23. Boiler Mountings
Safety Valves
The function of a safety valve is to
prevent the steam pressure in the
boiler exceeding the desired rated
pressure by automatically opening
and discharging steam to
atmosphere allowable pressure
falls back to normal rated value.
There are three types of safety
valves,
 Spring loaded (Rams bottom)
type,
 Dead weight type, and
 Lever type.

24. Turbine
A turbine is a type of engine
that can extract energy from a
fluid, such as water, steam,
air, or combustion gases. It
can be contrasted with a
piston engine which uses a
piston instead of a turbine to
extract energy.
I. Steam turbine
II. Water turbine
III. Wind turbine
IV. Gas turbine
A rotor of a modern steam turbine,used
in a power plant

25. Turbine
Steam Turbine
A steam turbine is a
prime mover in which
rotary
obtained
gradual change
motion is
by the
of
momentum of the
steam. In a steam
turbine the force
exerted on the blades
is due to the velocity
of steam.

26. Turbine
Types of steam
turbine
• Impulse turbine
• Reaction turbine

27. Turbine
Impulse turbine
A turbine that is driven by
high velocity jets of water or
from a nozzle
on to vanes or
attached to a
steam
directed
buckets
wheel. The resulting
impulse (as described by
Newton's second law of
motion) spins the turbine
and removes kinetic energy
from the fluid flow.

28. • Impulse turbine
• In impulse turbine, the drop in pressure of steam takes place in
a stationary nozzle.
• The drop in pressure leads to conversion of enthalpy into kinetic
energy of a fluid.
• Hence the velocity of the fluid increase at the expense of
temperature and pressure.
• This high velocity fluid (Jet) is deflected by a curved blade.
• A change in direction of a jet generates change in momentum of
the fluid.
• A rate of change in momentum will generate a force on the
blade.
• A motive power is generated, when this force can move the
blade.
Turbine

29. Turbine
Reaction turbine
A turbine in which the
working fluid is
accelerated by expansion
in both the static nozzles
and the rotor blades.
Torque is produced by
the momentum changes
in the rotor and by
reaction from fluid
accelerating out of the
rotor

30. • Reaction Turbine:
• In a Reaction Turbine drop in pressure occurs in a movable
nozzle.
• The drop in pressure leads to conversion of enthalpy into kinetic
energy of a fluid.
• Hence the velocity of the fluid increase at the expense of
temperature and pressure.
• A high velocity jet leaving the moving nozzle will generate a
reaction on the nozzle.
• A motive Power is generated, when this reaction can move the
nozzle.
Turbine

31. Steam Turbine Cycle
Thermodynamics Cycles
Gas Cycles Vapour Cycles
Working Fluid remains in Gaseous
Phase throughout the Cycle.
Working Fluid exists in Vapor
Phase during part of the Cycle, and
in liquid phase during remaining
part.

32. RANKINE CYCLE: THE IDEAL CYCLE
FOR VAPOR POWER CYCLES
Thr Rankine cycle, which is the ideal cycle for vapor power plants. Theideal
Rankine cycle does not involve any internal irreversibilities.
The simple ideal Rankine cycle

33. THE IDEAL REHEAT RANKINE CYCLE
How can we take advantage of the increased efficiencies at higher boiler pressures
without facing the problem of excessive moisture at the final stages of theturbine?
1. Superheat the steam to very high temperatures. It is limited metallurgically.
2. Expand the steam in the turbine in two stages, and reheat it in between(reheat)
The ideal reheat Rankine cycle.

34. Condenser
A condenser is designed to transfer heat from a working fluid
(e.g. water in a steam power plant) to a secondary fluid or the
surrounding air. The condenser relies on the efficient heat
transfer that occurs during phase changes, in this case during
the condensation of a vapor into a liquid.

35. Feed water pump
A boiler feed water pump is a specific type of
pump used to pump feed water into a steam
boiler. The water may be freshly supplied or
returning condensate produced as a result of the
condensation of the steam produced by the
boiler. These pumps are normally high pressure
units that take suction from a condensate return
system.

36. Feed water pump

37. Feed water pump
Classification of pump
There are two types of pump mainly used in
steam power plant:
1. Centrifugal pump
2. Reciprocating pump

38. Thank You