In these slides we explain three parts (1)steam turbines(2)steam generators(3)seam power plant.We also explain how these three parts cooperate with each other to make the whole system.

1. Steam
Power Plant

2. Group members
• Faizan Anwar (2013-EE-530)
• Salman khan (2013-EE-508)
• Ahmed Bilal (2013-EE-519)
• Zeeshan Ashraf (2013-EE-512)
• Raza Ehsan (2013-EE-515)
• Irfan Manzoor (2013-EE546)

3. contents
• Introduction
• Working and construction
• Design of power plant
• Characteristics of power plant
• Coal Handling
• Methods of fuel firing

4. Steam power plant
Steam is an important medium of producing
mechanical energy. Steam has the advantage
that, it can be raised from water which is
available in abundance it does not react much
with the materials of the equipment of power
plant and is stable at the temperature required
in the plant. Steam is used to drive steam
engines, steam turbines etc

5. Abundant usage of steam power plant:
• Steam power station is most suitable where coal is
available in abundance. Thermal electrical power
generation is one of the major method.
• Out of total power developed in India about 60% is
thermal. For a thermal power plant the range of pressure
may vary from 10 kg/cm2 to super critical pressures and
the range of temperature may be from 250°C to 650°C.
•
The average all India Plant load factor (P.L.F.) of thermal
power plants in 1987-88 has been worked out to be 56.4%
which is the highest P.L.F. recorded by thermal sector so far.

6. Steam power plant

7. Steam power plant components:
• steam power plant using steam as working substance works
basically on Rankine cycle.
• The different types of systems and components used in steam
power plant are as follows :
• (i) High pressure boiler
• (ii) Prime mover
• (iii) Condensers and cooling towers
• (iv) Coal handling system
• (v) Ash and dust handling system
• (vi) Draught system
• (vii) Feed water purification plant
• (viii) Pumping system
• (ix) Air preheater, economizer, super heater, feed heaters

8. Working :
• Coal received in coal storage yard of power station is
transferred in the furnace by coal handling unit.
• Heat produced due to burning of coal is utilized in
converting water contained in boiler drum into steam
at suitable pressure and temperature. The steam
generated is passed through the super heater.
• Superheated steam then flows through the turbine.
After doing work in the turbine die pressure of steam
is reduced.

9. To be contd:
• steam taken from the turbine at suitable extraction
points is sent to low pressure and high pressure water
heaters.
• Air taken from the atmosphere is first passed through
the air pre-heater, where it is heated by flue gases. The
hot air then passes through the furnace.
• The flue gases after passing over boiler and super
heater tubes, flow through the dust collector and then
through economiser, air pre-heater and finally they are
exhausted to the atmosphere through the chimney.

10. Power station design
• (i) Selection of site
• (ii) Estimation of capacity of power station
• (iii) Selection of turbines and their auxiliaries
• (iv) Selection of boilers, and their auxiliaries
• (v) Design of fuel handling system
• (vi) Selection of condensers
• (vii) Design of cooling system
• (viii) Design of piping system to carry steam and water
• (ix) Selection of electrical generator
• (x) Design and control of instruments.

11. Characteristics of steam power plant
• The desirable characteristic for a steam power
plant are as follows :
• (i) Higher efficiency
• (ii) Lower cost.
(iii) Ability to burn coal especially of high ash
content.
(iv) Reduced environmental impact in terms of
air pollution.
(v) Reduced water requirement.
(vi) Higher reliability and availability.

12. Coal handling

13. Explanation of steps in coal handling
.
Coal Delivery:
• The coal from supply points is delivered by ships
or boats to power stations situated near to sea or
river.
Unloading:
• The type of equipment to be used for unloading
the coal received at the power station depends
on how coal is received at the power station.

14. To be cont:
• Preparation:
When the coal delivered is in the form of big
lumps and it is not of proper size, the
preparation (sizing) of coal can be achieved by
crushers and breakers.

15. To be cont:
• Transfer:
• After preparation, coal is transferred to the dead
storage by means of following systems :
1. Belt conveyors.
2. Screw conveyors.
3. Bucket elevators.

16. Construction of belt conveyers
• It consists of an endless belt.
moving over a
pair of end drums (rollers).
• At some distance a
supporting roller is provided
at the center.
• The belt is made, up of
rubber or canvas. Belt
conveyor is suitable for the
transfer of coal over long
distances.
• It is used in medium and large
power plants.

17. Construction of screw conveyer
• It consists of an endless helicoid screw fitted to a
shaft.
• The screw while rotating in a trough transfers the
coal from feeding end to the discharge end.

18. Construction of bucket elevator
• It consists of buckets fixed
to a chain.
• The chain moves over
two wheels. The coal is
carried by the buckets
from bottom and
discharged at the top.

19. Method of fuel firing
The solid fuels are fired into the furnace by the following
methods :
1. Hand firing.
2. Mechanical firing
3. HAND FIRING:
This is a simple method of firing coal into the furnace. It
requires no capital investment. It is used for smaller
plants. This method of fuel firing is discontinuous process,
and there is a limit to the sizeof furnace which can be
efficiently fired by this method.

20. Mechanical handling
• Mechanical stokers are commonly used to feed solid fuels
into the furnace in medium and large size power plants.
•
The various advantages of stoker firing are as follows :
•
(i) Large quantities of fuel can be fed into the furnace. Thus
greater combustion capacity is achieved
• .
(ii) Poorer grades of fuel can be burnt easily.
•
(iii) Stoker save labour of handling ash and are self-
cleaning.

21. Content
• Boiler control
• Coal processing
• Coal firing
• Coal burners
• Water walls
• Ash disposal

22. Automatic Boiler Control
• Automatic combustion
control makes maintenance of
steam pressure and draught of
air and fuel more easy.
• Efficiency is increased and
manual labour is saved.
• One such system is Hagan
system of automatic
combustion control

23. Coal Processing
Coal is pulverized to increase its surface exposure thus permitting rapid
combustion.
Advantages
• Low grade coal can be burnt
easily
• Pulverized coal firing
requires low percentage of
excess air
• rate of combustion can be
adjusted easily to meet the
varying load
• fuel pulverizing equipment is
located outside the furnace,
Disadvantages
• It requires additional
equipment to pulverize the
coal
• Pulverized coal firing
produces fly ash (fine dust)
which requires a separate fly
ash removal
equipment.
• There are more chances of
explosion as coal burns like a

24. Coal Processing
• The pulverized coal is obtained by
processing the raw coal in pulverizing mills.
• The essential functions of pulverizing mills
are as follows:
 Drying of coal
 Grinding
 Separation of particles of the desired size.
• The coal pulverizing mills reduce coal to
powder form by two actions
 Attrition

25. Coal Processing
• Most of the mills use both the above mentioned
actions in varying degrees
• Two examples of such mills are
 Ball Mill:
It consists of a slowly rotating drum which is partly
filled with steel balls.
 Ball and Race Mill:
The coal is crushed between two moving surfaces
namely balls and races. The upper stationary race and
lower rotating race hold the balls between them.

26. Coal Firing
Pulverized coal
firing is done by
two systems
• Unit System or
Direct System
• Bin System or
Central System

27. Coal Firing
Unit system
• The system is simple and
cheaper than the central
system
• There is direct control of
combustion from the
pulverizing mill
• Coal transportation system
is simple
Central system
• The pulverizing mill grinds the
coal at a steady rate
irrespective of boiler feed
• There is always some coal in
reserve
• The initial cost of the system is
high
• Coal transportation system is
quite complicated
• The system requires more
space

28. Coal Burners
Long Flame Burner (U-flame) Short Flame Burner (turbulent)

29. Coal Burners
Tangential Burner Cyclone Burner

30. Water Walls
• The combustion space of a furnace is shielded
wholly or partially by small diameter tubes placed
side by side
• Water from the boiler is made to circulate through
these tubes which connect lower and upper
headers of boiler
 These walls provide a protection to the furnace against high temperatures
 They avoid the erosion of the refractory material and insulation
 The evaporation capacity of the boiler is increased

31. Ash Disposal
A large quantity of ash is produced in steam power
plants using coal
• Ash produced in about 10 to 20% of the total coal
burnt in the furnace
• Handling of ash is problematic because ash
coming out of the furnace is too hot and is
accompanied by some poisonous gases
• Handling of ash includes its removal from the
furnace, loading on the conveyors and delivered
to the fill from where it can be disposed off

32. Quenching of Ash
It is desirable to quench the ash before handling
• Quenching reduces the temperature of ash
• It reduces the corrosive action of ash
• Ash forms clinkers by fusing in large lumps
and by quenching clinkers will disintegrate

33. Steam Generators
2013-EE-519

34. Contents:
• Introduction
• Types of boilers
• Cochran boiler
• Lancashire Boiler
• Locomotive Boiler
• Babcock and Wilcox Boiler

35. Introduction
• Definition:
Boiler is an apparatus to produce steam. Thermal energy released
by combustion of fuel is transferred to water, which vaporizes
and gets converted into steam at the desired temperature and
pressure.

36. Boilers should fulfill following requirements
• Safety
• Accessibility
• Capacity
• Efficiency
• Construction
• Cost
• Quick Starting and Loading

37. Types of Boilers
• According to Flow of water and hot Gasses
1. Water Tube Boiler
2. Fire Tube Boiler

38. Advantages Of Water Tube Boiler
• Less explosion Chances
• Less Space
• High Pressure
• Heating Surface
• Greater Efficiency
• Less weight

39. Advantages of Fire Tube
• Low Cost
• Compact in Size
• Water Volume is Large

40. COCHRAN Boiler

41. Lancashire Boilers

43. Locomotive Boiler

44. Babcock and Wilcox Boiler

45. Contents
• Merits of Water tube boilers over Fire Tube
Boilers.
• Demerits of water Tube Boilers.
• High Pressure Boiler.
• LAMONT Boiler.
• Benson Boiler.
• Loeflar Boiler.

46. Merits of Water Tube Boilers Over Fire
Tube Boilers
 Generation of steam is much quicker.
 Evaporation capacity and steam pressure
range is also high.
 Heating surfaces are more effective.
 Combustion Efficiency is higher.
 They are also known as safety boilers.

47. Demerits of Water Tube boilers Over Fire
Tube Boilers
 It is less suitable for impure and sedimentary
water.
 They require careful attention.
 Maintanence cost is high.

48. Requirements of a good Boiler
 Capable to generate steam at given pressure and
temperature.
 Initial, Installation and maintanence cost should be low.
 Should be light in weight and have small surface area.
 Able to meet fluctuating Demands.
 should be minimum of joints.
 Water and fluid velocities should be high.
 There should be not deposition of mud.

49. High Pressure Boilers
 Efficiency and capacity of Plant can be
increased.
 Tendency of scale formation is reduced.
 Damage of overheating is reduced.
 Differential Expansion is reduced.
Provides freedom in arrangement of furnace
and water walls.

50. Types of High Pressure Boiler
 La Mont Boiler.
 Benson Boiler.
 Loefler Boiler.

51. LAMONT BOILER
 Forced Circulation of water Occur in this boiler.
Its main parts are
 Air Pre-Heater
 Economiser
 Radiant Super heater .
 Convective Super Heater
 It produces 40-50 tones of steam at 120 bar and
500 C temperature.

53. Benson Boiler
 It is high pressure water tube boiler.
 It works on Critical Pressure.
 What is critical Pressure?
 Water will enter just above the critical
pressure so it suddenly converted into steam.

55. Advantages of Benson Boiler
 Transport is easy.
 Need small floor area.
 Furnace walls are well protected.
 Started very quickly.
 Explosion hazards are not so severe.

56. Loefler Boiler
 Deposition of salt and sediments in Benson
boiler.
 Deposition Reduces heat transfer and heat
generating capacity.
 Stopping flow of water into the boiler tubes.
 Steam is generated outside from the feed
water.

57. Loeflar Boiler

58. STEAM TURBINE

59. What is Steam Turbine
Steam turbine is a machine capable of
transforming thermal energy (from
steam) to mechanical energy.
OR
Steam Turbine is a prime mover in which,
heat energy is transformed into
mechanical energy.

60. Purpose of Steam Turbine
Broadly speaking, Purpose of Steam turbines is divided into
two broad categories:
–Generating Electric Power
–General - Purpose units used for driving
pumps, compressors etc.
In both cases Steam Turbine will act as a prime mover.

61. Principle of Working
• High pressure steam enters through
nozzles.
• The stationary blades direct the steam
flow towards the moving blades.
• The direction of the steam flow
changes as it flows through the moving
blades.
• The change of flow direction generates
a force on the moving blades.
• This force drives the turbine.

62. Parts of Turbine
High Pressure Parts:
– Governor Valve
– Trip Valve – Trip & Throttle Valve
– Steam Chest
– Nozzles
Low Pressure Parts:
– Casing
– Blades
– Seals

63. – Glands or Seals
Rotor Assembly
– Blades or buckets
– Disks
– Shaft
Other Parts
– Bearings (Radial & Thrust)
– Turning Gear

65. Steam
Nozzle
Stationary
Blade
Movin
g
Blade

66. Lubrication System
There are mainly two types of turbine lubrication
systems
– Oil Ring Lubrication system
– Forced Lubrication System
Bearings
Two types of bearings are mainly used in the
turbine
– Radial Bearing or Journal Bearing
– Thrust Bearing

67. Shut Down of Steam Turbine
Following are the main steps involved in
the shut down of steam turbine,
–Lowering of Speed to minimum controllable
–Stop the turbine with shutdown push
button
–Isolation of the steam inlet and outlet
valves
–Opening of all drain points
–Cooling and shutdown of auxiliary systems

68. Monitoring Parameters During Operation
–Excessive Casing Pressure
–Condensation of Steam
–Quality of Steam
–Healthiness of the Instruments & Fittings
–Vibrations
–Contamination of the oil system
–Seals leakage
–Critical Speed

69. Choice of Steam Turbine
The choice of steam turbine depends on the
following factors
• Capacity of plant
• Plant load factor and capacity factor
• Thermal efficiency
• Reliability
• Location of plant with reference to availability
of water for condensate

70. Advantages of Steam Turbine Over
Steam Engine
The various advantages of steam turbine are as follows:
• It require less space.
• Its over-load capacity is large. It can be designed for much
greater capacities as compared to steam engine.
• In steam turbine steam consumption does not increase with
increase in years of service.
• In steam turbine power is generated at uniform rate.
• It can be designed for much higher speed and greater range
of speed.
• The thermodynamic efficiency of steam turbine is higher.

71. Steam Turbine Specifications
Steam turbine specification consist of following:
1.Turbine rating. It includes:
• Turbine kilowatts
• Generator voltage
• Phases
• Frequency
• Power factor
2.Steam Conditions
3.Governing arrangements

72. Types Of Steam Turbine
Steam turbines are categorized by the
following three different ways:
–From working principle
• Impulse Turbine
• Reaction Turbine
–From number of stages
• Single stage turbine
• Multi stage turbine

73. –From how steam is utilized
•Condensing turbine
•Back pressure (non-condensing)
turbine
•Extraction turbine
•Induction turbine

74. Impulse Principle
• If steam at high pressure is allowed to expand through a stationary nozzle,
the result will be a drop in steam pressure and an increase in steam
velocity. If the direction of this high velocity steam changed by passing it
through a properly shaped turbine blade, will generate an impulse force.
This impulse force will cause the blade to move. Steam
In
Steam Out
Impuls
e Force
Impulse Blade

76. Classification of Steam Turbine
1. On basis of principle of operation
2. On the basis of Direction of Flow
3. On the Basis of Means of Heat Supply
4. On the Basis of Means of Heat Rejection
5. On the Basis of Number of Cylinder
6. On the Basis of Rotational Speed
7. On the Basis of Arrangement of Cylinder Based on General
Flow of Steam
8. On the Basis of Number of Shaft

77. On the Basis of Principle of Operation
(i) Impulse turbine
1) Simple
2) Velocity stage
3) Pressure stage
4) combination of (2) and (3)
(ii) Impulse-reaction turbine
1) Reaction
2) Combination of impulse and reaction.

78. Impulse Turbine
 If the flow of steam through the nozzles and moving blades of a
turbine takes place in such a manner that the steam is expanded
only in nozzles and pressure at the outlet sides of the blades is
equal to that at inlet side.
 Such a turbine is termed as impulse turbine because it works on
the principle of impulse.
 In other words, in impulse turbine, the drop in pressure of steam
takes place only in nozzles and not in moving blades.
 This is obtained by making the blade passage of constant cross-
section area.

79. Impulse-Reaction Turbine
 In this turbine, the drop in pressure of steam takes place in fixed
(nozzles) as well as moving blades.
 The pressure drop suffered by steam while passing through the
moving blades causes a further generation of kinetic energy
within the moving blades, giving rise to reaction and adds to the
propelling force which is applied through the rotor to the turbine
shaft.
 Since this turbine works on the principle of impulse and reaction
both, so it is called impulse-reaction turbine.
 This is achieved by making the blade passage of varying cross-
sectional area.

80. On the basis of “Direction of Flow’’
a) Axial flow turbine,
b) Radial flow turbine,
c) Tangential flow turbine
On the Basis of Means of Heat Supply:
a) Single pressure turbine,
b) Mixed or dual pressure turbine
c) Reheated turbine
Single (b) Double

81. On the Basis of Means of Heat Rejection
1. Pass-out or extraction turbine
2. Regenerative turbine
3. Condensing turbine
4. Noncondensing turbine
5. Back pressure or topping turbine
On the Basis of Number of Cylinder
1. Single cylinder
2. Multi-cylinder
On the Basis of Number of Shaft
1. Tandem compound
2. Cross compound

82. On the Basis of Arrangement of Cylinder Based on General Flow
of Steam.
1) Single flow
2) Double flow
3) Reversed flow
On the Basis of Rotational Speed
1. Constant speed turbines
N = 120 f/p
2. Variable speed turbines

83. Compounding Of Impulse Turbine
 Compounding is a method for reducing the rotational speed of the
impulse turbine to practical limits.
 If the high velocity of steam is allowed to flow through one row of
moving blades, it produces a rotor speed of about 30,000 r.p.m.
which is too high for practical use. Not only this the leaving loss is
also very high.
 It is therefore essential to incorporate some improvements in the
simple impulse turbine for practical use and also to achieve high
performance.

84.  This is possible by making use of more than one set of nozzles,
blades, rotors, in a series, keyed to a common shaft, so that either
the steam pressure or the jet velocity is absorbed by the turbine in
stages.
 The leaving loss also will then be less. This process is called
compounding of steam turbines.
 There are three main types
(a) Pressure-compounded impulse turbine.
(b) Velocity-compounded impulse turbine.
(c) Pressure and velocity compounded impulse turbine.

85. In this type of turbine, the
compounding is done for velocity of
steam only i.e. drop in velocity is
arranged in many small drops
through many moving rows of blades
instead of a single row of moving
blades.
It consists of a nozzle or a set
of nozzles and rows of moving blades
attached to the rotor or wheel and
rows of fixed blades attached to
casing as shown in Fig.
SIMPLE VELOCITY-COMPOUNDED IMPULSE TURBINE

86. Impulse Reaction Turbine
 As the name implies this type of turbine utilizes the principle of impulse and
reaction both.
 There are a number of rows of moving blades attached to the rotor and an
equal number of fixed blades attached to the casing.
 In this type of turbine, the steam velocities are comparatively moderate and
its maximum value is about equal to blade velocity.
 In general practice, to reduce the number of stages, the steam velocity is
arranged greater than the blade velocity.
 In this case the leaving loss is about 1 So 2 per cent of the total initial available
energy.
 This type of turbine is used mostly in all power plants where it is great
success.
 An example of this type of turbine is the Parsons-Reaction Turbine.
 The power plants 30 MW and above are all impulse-reaction type

88. STEAM TURBINE CAPACITY
 The capacities of small turbines and coupled generators vary from 500 to 7500
kW whereas large turbo alternators have capacity varying from 10 to 90 MW.
Very large size units have capacities up to 500 MW.
 Generating units of 200 MW capacity are becoming quite common.
 The steam consumption by steam turbines depends upon steam pressure, and
temperature at the inlet, exhaust pressure number of bleeding stages etc.
 The steam consumption of large steam turbines is about 3.5 to 5 kg per kWh.
 Turbine kW = Generator kW / Generator efficiency
 Generators of larger size should be used because of the following reasons:
Higher efficiency.
Lower cost per unit capacity.
Lower space requirement per unit capacity.

89. Steam Turbine Governing
Governing of steam turbine means to regulate the supply of
steam to the turbine in order to maintain speed of rotation
sensibly constant under varying load conditions.
Some of the methods employed are as follows :
1. Bypass governing
2. Nozzle control governing
3. Throttle governing.
Types of Governor
1.Fly Ball Governor
2.Hydraulic Governor
3.Oil Relay Governor
4.Electronic Governor

90. Steam Turbine Testing
1. Power
2. Valve setting
3. Speed regulation
4. Over speed trip setting
5. Running balance
Thermal efficiency of steam turbine depends on the
following factors
1. Steam pressure and temperature at throttle valve of turbine.
2. Exhaust steam pressure and temperature.
3. Number of bleedings.
Lubricating oil should be changed or cleaned after 4 to 6 months