Applied Thermodynamics

2. STEAM TURBINE
http://sumit/steamturbine.com

3. Contents:
What is Turbine?
What is Steam turbine?
Components of Steam turbine?
Principle of Steam turbine?
Types of Steam turbine?
Difference b/w Impulse and Reaction Turbine
Advantages of Steam turbine?
Disadvantages of Steam turbine?
Classification of Steam Turbine:

4. What is Turbine?
A Turbine is an engine that converts energy
of fluid into mechanical energy.
OR
A Turbine is a device which converts the
heat energy into the kinetic energy & then to
rotational energy.

5. What is steam turbine?
Steam Turbine is a prime mover in which
pressure energy of steam is converted into
mechanical energy & further electrical energy
OR
A steam turbine is a device that extracts thermal
energy from pressurized steam and uses it to
do mechanical work on a rotating output shaft.

6. Components of Steam turbine
Main components are
 Casing
 Rotor
 Blades
 Stop and control valve
 Oil befell, steam befell
 Bearing
 Gear box
 Oil pumps

7. Principle of Steam turbine:
An ideal steam turbine is considered to be
an isentropic process, or constant entropy
process, in which the entropy of the steam
entering the turbine is equal to the entropy of
the steam leaving the turbine. No steam turbine
is truly isentropic, however, with typical
isentropic efficiencies ranging from 20–90%
based on the application of the turbine.

8. Types of steam turbine?
There are two main types of Steam
turbine:
1. Impulse turbine
2. Reaction turbine

9. Impulse turbine:
In this type, the drop in pressure
takes place in fixed nozzles as well as
moving blades. The pressure drops
suffered by steam while passing
through the moving blades causes a
further generation of kinetic energy
within these blades, giving rise to
reaction and add to the propelling force,
which is applied through the rotor to the
turbine shaft. The blade passage cross-
sectional area is varied (converging
type).

10. Reaction turbine:
In the reaction turbine high
pressure steam from the boiler,
passes through the nozzle.
When the steam comes out
through these nozzles the
velocity of steam increases &
then strike on fixed blade. In this
type of turbine there is a
gradually pressure drop takes
place over fixed & moving blade.

11. Difference b/w Impulse and Reaction
Turbine :
Impulse Stage:
Whole pressure drop in nozzle
(whole enthalpy drop is changed into
kinetic energy in the nozzle).
Reaction stage:
Pressure drop both in
stationary blades and in rotary blades
(enthalpy drop changed into kinetic
energy both in stationary blades and
in rotary blades).

12. Advantages of Steam turbine:
 Thermal Efficiency of a Steam Turbine is much higher than that of a steam
engine.
 The Steam Turbine develops power at a uniform rate and hence does not
required Flywheel.
 If the Steam Turbine is properly designed and constructed then it is the most
durable Prime Mover.
 In a steam turbine there is no loss due to initial condensation of steam.
 In Steam Turbine no friction losses are there.

13. Disadvantages of Steam turbine:
 High efficiency is ordinarily obtained only at high speed.
 Gas turbine locomotives had similar problems, together with a range
of other difficulties.
 These devices are heavy.
 Turbines can rotate in only one direction

14. Classification of Steam Turbine
Steam turbine can be classified into three
categories:
1. Axial flow
2. Radial flow
3. Reverse flow

15. Axial flow:
The great majority of turbines, especially those of
high power, are axial flow. In such turbines the steam flow
in a direction or direction parallel to the axis of wheel or
rotor.
The axial flow type of turbine is the most preferred
for electricity generation.

16. Radial flow:
A turbine may also be constructed so that the steam
can flow is in a radial direction, either toward or away from
the axis.
The radial turbine is not normally the preferred
choice for electricity generation and it is mostly used for
small output applications.

17. Reverse flow:
In some modern turbines design the steam flows
through part of the high pressure (HP) cylinder and then is
reversed to flow in the opposite direction through the
remainder of the HP cylinder.
A simplified diagram of a reverse flow is shown in
Figure:

18. THANK
YOU!