This document discusses different types of steam turbines based on their operating principles and design. Steam turbines can be classified based on how steam expands through the turbine (impulse, reaction, or a combination), the number of pressure stages, the direction of steam flow, the number of cylinders, the method of governing steam flow, the steam conditions, and their application in stationary or non-stationary systems. Common types include impulse, reaction, and mixed-flow turbines. The document compares impulse and reaction turbines and discusses methods for reducing turbine speed under varying loads.

1. MOHAMMED FARIS A K
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2.  The steam turbine is a prime mover in which
the potential energy of steam is transformed
into kinetic energy , and latter in its turn is
transformed to mechanical energy of rotation
of the turbine shaft.
 Utilised in most diverse fields of industry, for
power generation and for transport

3.  Based on action of steam
 Impulse
 Reaction
 Combination of impulse and reaction
 Based on number of pressure stages
 Single stage
 Multi stage Impulse and Reaction turbines
 Based on Direction of steam flow
 Axial turbines
 Radial turbines
 Based on no of cylinders
 Single
 Double
 Three cylinder
 Four cylinder

4.  Based on method of governing
 Throttle governing
 Nozzle governing
 According to heat drop process
 Condensing turbines with generators
 Back pressure turbines
 Topping turbines
 Low pressure turbines
 Mixed pressure turbines
 According to steam conditions at inlet
 Low pressure (1.2-2 atm)
 Medium pressure ( upto 40 atm )
 High pressure (above 40 atm )
 Very high pressure ( 170 atm and above and temp of 550 C and
above )
 Super critical (above 225 atm )
 Based on usage in industry
 Stationary ( variable and constant speed )
 Non stationary

5. Advantages of Steam Turbine over
the Steam Engines
• Thermal efficiency higher for steam turbine
• Power generation at uniform rate
• Higher speeds and higher outputs
• No internal lubrication and minimised balancing
problem
• No loss due to initial condensation of steam
• Utilise high vaccum very advantageously

6. COMMON TYPES OF TURBINES
• Simple impulse turbine
Steam expands in the nozzles and its pressure
does not alter as it moves over the blades.
Eg: De laval turbine
Expansion takes place in one set of nozzles.

7. • Reaction turbine
Steam expands continuously as it passes
over the blades and thus there is gradual fall in the
pressure during expansion. No of stages required is
more.

8. Sl
no
Particulars Impulse Turbine Reaction Turbine
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Pressure drop
Area of blade
channels
Blades
Admission of
steam
Nozzles
Power
Space
Efficiency
Suitability
Blade
manufacture
Only in nozzles and not in
moving blades.
Constant.
Profile type.
Not all round.
Diaphragm contains the
nozzles.
Small power capacities.
Less space for same power.
Low
Small power requirements.
Easy
In fixed blades(nozzles) as
well as in moving blades.
Varying.
Aerofoil type.
All round.
Fixed blades attached to the
casing.
Much power can be
developed.
More space required.
High
For medium and high
power requirements.
Difficult

9. Methods for reducing rotor speed
• Velocity compounding

10. • Pressure compounding

11. • Pressure velocity compounding

12. Objective is to keep turbine speed fairly
constant irrespective of load . Different methods
are
• Throttle governing

13. • Nozzle governing
• By pass governing

14. Sl no. Particulars Throttle control Nozzle control
1.
2.
3.
4.
5.
Throttling losses
Partial admission
losses
Heat drop
available
Use
Suitability
Severe
Low
Lesser
In both Impulse and
Reaction turbines.
Small turbines
Little losses
High
Larger
Mostly in Impulse
turbine.
Medium and Large
turbines.