2. Table of Contents
1. Basic Electricity............................................................................................0
1.1. Electron Theory......................................................................................0
1.2. Magnetism and Electromagnetism Explained........................................1
1.3. Introduction to Alternating Current (AC)................................................0
1.4. AC Induction Motors..............................................................................0
1.5. AC Generators .......................................................................................1
1.6. Transformer Basic Operation and Theory ..............................................2
2. Power Plant Basics.......................................................................................0
2.1. Energy Conversion ....................................................................................1
2.2. Steam Turbine Basics.............................................................................2
2.3. Combustion System Component Overview.............................................3
2.4. Internal Combustion System Component Overview ...............................5
2.5. Boiler Water and Steam Cycle Overview................................................0
2.6. Generator Overview...............................................................................1
3. Plant Instrumentation and Control Theory...................................................1
3.1. Instrumentation and Control Overview..................................................2
3.2. Temperature Instruments......................................................................0
3.3. Pressure Measuring Devices ..................................................................0
3.4. Level Measuring Devices........................................................................3
3.5. Flow Measuring Devices ........................................................................0
3.6. Introduction to Automated Control........................................................0
4. Intro to Plant Equipment..............................................................................0
4.1. Introduction to Pumps ...........................................................................0
4.2. Introduction to Valves and Their Components .......................................1
4.3. Heat Exchanger Theory..........................................................................3
3. 4.4. Introduction to Hydraulics .....................................................................1
5. Plant Drawings ............................................................................................2
5.1. P&ID Basics............................................................................................2
5.2. Reading a P&ID......................................................................................0
6. Plant Systems...............................................................................................0
6.1. Introduction to Combustion Air and Flue Gas Systems...........................0
6.2. Introduction to the Circulating Water System........................................0
6.3. Introduction to the Condensate System.................................................0
6.4. Introduction to the Feedwater System...................................................0
7. Turbines.......................................................................................................0
7.1. Steam Turbine Design............................................................................0
7.2. Steam Turbine Valves and Controls........................................................2
7.3. Steam Turbine Auxiliaries ......................................................................0
8. Internal combustion Engines........................................................................1
8.1. Combustion Turbine Fundamentals .......................................................1
8.2. Introduction to Gas Turbines .................................................................2
8.3. Gas Turbines major components............................................................3
8.4. Introduction to Internal Combustion Engine ...........Error! Bookmark not
defined.
9. Boilers & Boiler Fuel Systems .......................................................................0
9.1. Coal Handling System ............................................................................0
9.2. Boiler Fuel System..................................................................................0
10. Power Generation.....................................................................................0
10.1. Generator and Auxiliary Systems’ Functions.......................................0
10.2. Generator and Auxiliary Systems’ Flow Paths and Major Components
1
10.3. Environmental Protection...................................................................1
10.4. Flue Gas Desulfurization System.........................................................1
11. Electrical Systems and Equipment.............................................................0
4. 11.1. Protection Relays................................................................................0
11.2. Generator, Transformer and Motor Protection...................................0
11.3. Grounding and Bonding......................................................................2
11.4. Main Transformers .............................................................................2
11.5. Fuses and Circuit Breakers..................................................................1
12. Steam Tables ............................................................................................0
12.1. Understanding the Basic Properties of Water and Steam ...................0
13. Basic Water Chemistry and Treatment .....................................................0
13.1. Corrosion Control in a Power Plant .....................................................1
13.2. Corrosion Control in a Power Plant .....................................................2
5. 1. Basic Electricity
So what is electricity and where does it come
from? In its simplest terms, electricity is the
movement of charge, which is considered by
convention to be, from positive to negative.
No matter how the charge is created,
chemically (like in batteries), the movement
of the discharge is electricity.
1.1. Electron Theory
There is an equal number of electrons and
protons in an atom. Hence, atom is in
general electrically neutral. As the protons in
the central nucleus are positive in charge
and electrons orbiting the nucleus, are
negative in charge, there will be an attraction
force acts between the electrons and
protons. In an atom various electrons
arrange themselves in different orbiting
shells situated at different distances from the
nucleus.
The force is more active to the electrons
nearer to the nucleus, than to the electrons
situated at outer shell of the atom. One or
more of these loosely bonded electrons may
be detached from the atom. The atoms with
6. lack of electrons are called ions. Due to lack
of electrons, compared to number of
protons, the said ion becomes positively
charged. Hence, this ion is referred as
positive ion and because of positive
electrical charge; this ion can attract other
electrons from outside.
The electrons which move from atom to
atom in random manner are called free
electrons. When a voltage is applied across
a conductor, due to presence of electric field,
the free electrons start drifting to a particular
direction according the direction of voltage
and electric field. This phenomenon causes
current in the conductor.
The movement of electrons, means
movement of negative charge and rate of
this charge transfer with respect to time is
known as current.
7. Conventional Flow of Current Vs Electrons
Flow
In the early days, it was thought that the
current is, flow of positive charge and hence
current always comes out from the positive
terminal of the battery, passing through the
external circuit and enters in the negative
terminal of the battery. This is called
conventional flow of current.
The true electron flow
The actual cause of current in a conductor is
due to movement of free electrons and
electrons have negative change. Due to
negative charge, electrons move from the
negative terminal to the positive terminal of
the battery through the external circuit. So
the conventional flow of current is always in
the opposite direction of electrons flow. The
true electron flow is used only when it is
necessary to explain certain effects (as in
semiconductor devices such as diodes and
transistors).
Conductors, Insulators and Semiconductors
Materials can be classified as conductors,
insulators, and semiconductors according
8. the ability of the material to allow the flow of
electricity. All materials have a measurable
property called electrical conductivity that
indicates the ability of the material to either
allow or impede the flow of electrons.
Materials that easily conduct electricity have
a high conductivity.
Conductor
A conductor is a material that readily allows
the flow of electricity. Metal wires are usually
good conductors, though some metals are
better conductors than others. Copper,
aluminium, silver and gold are examples of
good conductors. Compared to non-
conductors, these materials have a high
electrical conductivity.
Insulator
An insulator is a material that is a poor
conductor. We say that an insulator tends to
prevent the flow of electricity. Rubber, wood,
ceramics and air are examples of good
insulators. Compared to conductors, these
materials have a low electrical conductivity.
If a positively charged region is separated
from a negatively charged region by a
conductor, then electrical current will flow
9. between the regions. If instead the positively
charge region is separated from a negatively
charged region by an insulator, little or no
electrical current will flow.
10. Semiconductor
A semiconductor is a material that has an
intermediate tendency to allow the flow of
electrons, i.e. it is somewhere between an
insulator and a conductor. The conductivity
of semiconductor materials can be changed
by the presence of an electrical field,
exposure to light, or the application of
mechanical pressure or heat. The ability to
change the apparent electrical conductivity
by introducing these stimuli allows
semiconductors to be used as the building
blocks of semiconductor devices.
Semiconductor devices are like switches
that allow electricity to flow. Sometimes that
switching is controlled intentionally to control
the flow of electricity, for examples in LEDs
(light emitting diodes) and transistors. Other
times the switching of the flow of electricity is
passive and controlled by the environment,
for example in photovoltaic solar cells or
semiconductor sensors.
Transistors
Transistors are semiconductor devices that
can be used to switch or amplify electrical
currents. Digital logic and computing devices
11. like microprocessors, communication chips,
and signal processing chips can have
hundreds, thousands, millions or billions of
transistors.
1.2. Magnetism and Electromagnetism
Magnetism is one aspect of the combined
electromagnetic force. It refers to physical
phenomena arising from the force caused by
magnets, objects that produce fields that
attract or repel other objects.
The motion of electrically charged particles
gives rise to magnetism. The force acting on
an electrically charged particle in a magnetic
field depends on the magnitude of the
charge, the velocity of the particle, and the
strength of the magnetic field.
Magnet has a north pole and a south pole.
Opposite poles attract each other (north and
south) and similar poles repel each other
(north-north or south-south)
There are several different types of
magnets.
Permanent magnets are magnets that
permanently retain their magnetic field. This
12. is different from a temporary magnet, which
usually only has a magnetic field when it is
placed in a bigger, stronger magnetic field,
or when electric current flows through it
Another type of temporary magnet, called an
electromagnet, uses electricity to create a
magnet.
13. Electromagnetism
When a wire is moved in a magnetic field,
the field induces a current in the wire.
Conversely, a magnetic field is produced by
an electric charge in motion. This is the
Faraday’s Law of Induction, which is the
basis for electromagnets, electric motors
and generators. A charge moving in a
straight line, as through a straight wire,
generates a magnetic field that spirals
around the wire. When that wire is formed
into a loop, the field becomes a doughnut
shape, or a torus.
The applications of electromagnets are
nearly countless. Faraday’s Law of Induction
forms the basis for many aspects of our
modern society including not only electric
motors and generators, but electromagnets
of all sizes.
14. 1.3. Introduction to Alternating Current
Alternating current (AC), is an electric
current in which the flow of electric charge
periodically reverses direction, whereas in
direct current (DC, also dc), the flow of
electric charge is only in one direction
AC is the form in which electric power is
delivered to businesses and residences. The
usual waveform of alternating current in
most electric power circuits is a sine wave.
Electric power is distributed as alternating
current because AC voltage may be
increased or decreased with a transformer.
This allows the power to be transmitted
through power lines efficiently at high
voltage, which reduces the power lost as
heat due to resistance of the wire, and
transformed to a lower, safer, voltage for
use. Use of a higher voltage leads to
significantly more efficient transmission of
power.
Power transmitted at a higher voltage
requires less loss-producing current than for
the same power at a lower voltage. Power is
often transmitted at hundreds of kilovolts,
15. and transformed to 100–240 volts for
domestic use.
High voltage transmission lines deliver
power from electric generation plants over
long distances using alternating current.
Three-phase electrical generation is very
common. The simplest way is to use three
separate coils in the generator stator,
physically offset by an angle of 120° (one-
third of a complete 360° phase) to each
other. Three current waveforms are
produced that are equal in magnitude and
120° out of phase to each other. If coils are
added opposite to these (60° spacing), they
generate the same phases with reverse
polarity and so can be simply wired together.
In three phase circuit, connections can be
given in two types:
Star connection
Delta connection
16. 1.4. AC Induction Motors
One of the most common electrical motor
used in most applications is induction motor.
This motor is also called as asynchronous
motor because it runs at a speed less than
its synchronous speed. Here we need to
define what synchronous speed is.
Synchronous speed is the speed of rotation
of the magnetic field in a rotary machine and
it depends upon the frequency and number
poles of the machine.
An induction motor always runs at a speed
less than synchronous speed because the
rotating magnetic field which is produced in
the stator will generate flux in the rotor which
will make the rotor to rotate, but due to the
lagging of flux current in the rotor with flux
current in the stator, the rotor will never
reach to its rotating magnetic field speed i.e.
the synchronous speed.
Working Principle of Induction Motor
We need to give double excitation to make a
machine to rotate. For example a DC motor,
need one supply to the stator and another to
the rotor through brush arrangement. But in
induction motor require only one supply.
17. Actually the supply is given to the stator
winding, flux will generate in the coil due to
flow of current in the coil. Now the rotor
winding is arranged in such a way that it
becomes short circuited in the rotor itself.
The flux from the stator will cut the coil in the
rotor and since the rotor coils are short
circuited, according to Faraday's law of
electromagnetic induction, current will start
flowing in the coil of the rotor. When the
current will flow, another flux will get
generated in the rotor. Now there will be two
flux, one is stator flux and another is rotor
flux and the rotor flux will be lagging wth
regard to the stator flux. Due to this, the rotor
will feel a torque which will make the rotor to
rotate in the direction of rotating magnetic
flux. So the speed of the rotor will be
depending upon the ac supply and the speed
can be controlled by varying the input
supply. This is the working principle of an
induction motor of either type single and
three phase.
1.5. AC Generators
The turning of a coil in a magnetic field
produces motional emfs in both sides of the
18. coil which add. Since the component of the
velocity perpendicular to the magnetic field
changes sinusoidal with the rotation, the
generated voltage is sinusoidal or AC. This
process can be described in terms of
Faraday's law when you see that the rotation
of the coil continually changes the magnetic
flux through the coil and therefore generates
a voltage.
1.6. Transformer Basic Operation and
Theory
Electrical power transformer is a static
device which transforms electrical energy
from one circuit to another without any direct
electrical connection and with the help of
mutual induction between two windings. It
transforms power from one circuit to another
without changing its frequency but may be in
different voltage level.
Working Principle of Transformer
The working principle of transformer is very
simple. It depends upon Faraday's law of
electromagnetic induction. Actually, mutual
induction between two or more winding is
19. responsible for transformation action in an
electrical transformer.
The alternating current through the winding
produces a continually changing flux or
alternating flux that surrounds the winding. If
any other winding is brought nearer to the
previous one, obviously some portion of this
flux will link with the second. As this flux is
continually changing in its amplitude and
direction, there must be a change in flux
linkage in the second winding or coil.
According to Faraday's law of
electromagnetic induction, there must be an
EMF induced in the second. If the circuit of
the later winding is closed, there must be a
current flowing through it. This is the most
basic of working principle of transformer.
The three main parts of a transformer are,
Primary Winding of Transformer
Which produces magnetic flux when it is
connected to electrical source.
Magnetic Core of Transformer-
The magnetic flux produced by the primary
winding, that will pass through this low
reluctance path linked with secondary
20. winding and create a closed magnetic
circuit.
Secondary Winding of Transformer-
The flux, produced by primary winding,
passes through the core, will link with the
secondary winding. This winding also
wounds on the same core and gives the
desired output of the transformer.
21. 2. Power Plant Basics
Energy comes in various forms but electrical
energy is the most convenient form of
energy since it can be transported with ease,
generated in a number of different ways, and
can be converted into mechanical work or
heat energy as and when required.
The Power Plant
Power or energy is generated in a power
plant which is the place where power is
generated .Energy cannot be created or
destroyed but merely changed from one
form to the other. More correctly, a power
plant can be said to be a place where
electrical energy is obtained by converting
some other form of energy. The type of
energy converted depends on what type of
power plant.
Types of Power Plants
There are several different types of power
plants used across the world
22. Thermal Power Plants
These power plants convert heat energy into
electrical energy. The working fluid of these
plants is mostly steam and they work on the
Rankine cycle. A steam power plant consists
of a boiler which is used to generate the
steam from water, a prime mover like a
steam turbine to convert the enthalpy of the
steam into rotary motion of the turbine which
is linked to the alternator to produce
electricity. The steam is again condensed in
the condenser and fed to the boiler again.
Hydro Power Plants
These plants use the kinetic energy of
flowing water to rotate the turbine blades,
hence converting kinetic energy into
electrical energy. These types of power
plants are very good for peak loads. Their
main disadvantage lies in the fact that their
location depends on a number of factors
which are beyond the control of human
beings such as the hydrological cycle of the
region and so forth. If there is shortage of
water it could lead to shut down of these
plants.
23. Apart from these main two types there are
plants which use nuclear energy, solar
energy and even wind energy to generate
power.
3. Energy Conversion
Energy transformation or energy conversion
is the process of changing one form of
energy to another form of energy. In physics,
the term energy describes the capacity to
produce certain changes within any system,
without regard to limitations in
transformation imposed. Changes in total
energy of systems can only be
accomplished by adding or removing energy
from them, as energy is a quantity which is
conserved (unchanging), as stated by the
first law of thermodynamics. Mass-energy
equivalence, which rose up from special
relativity, states that changes in the energy
of systems will also coincide with changes
(often small in practice) in the system's
mass, and the mass of a system is a
measure of its energy content.
Energy in many of its forms may be used in
natural processes, or to provide some
service to society such as heating,
24. refrigeration, light, or performing mechanical
work to operate machines. For example, an
internal combustion engine converts the
potential chemical energy in gasoline and
oxygen into thermal energy which, by
causing pressure and performing work on
the pistons, is transformed into the
mechanical energy that accelerates the
vehicle (increasing its kinetic energy).
3.1. Steam Turbine Basics
A steam turbine is powered by the energy in
hot, gaseous steam and works like a cross
between a wind turbine and a water turbine.
Steam turbines use high-pressure steam to
turn electricity generators at incredibly high
speeds. A typical power plant steam turbine
rotates at 1800–3600 rpm. Which needs to
use a gearbox to drive a generator quickly
enough to make electricity.
Just like in a steam engine, the steam
expands and cools as it flows past a steam
turbine's blades, giving up as much as
possible of the energy it originally contained.
The flow of the steam turns the blades
continually:
25. Electrical energy generation using steam
turbines involves three energy conversions,
extracting thermal energy from the fuel and
using it to raise steam, converting the
thermal energy of the steam into kinetic
energy in the turbine and using a rotary
generator to convert the turbine's
mechanical energy into electrical energy.
3.2. Combustion System Component
Overview
Combustion is a chemical process in which
a substance reacts rapidly with oxygen and
gives off heat. The original substance is
called the fuel, and the source of oxygen is
called the oxidizer. The fuel can be a solid,
liquid, or gas, although for airplane
propulsion the fuel is usually a liquid. The
oxidizer, likewise, could be a solid, liquid, or
gas, but is usually a gas (air) for airplanes.
For model rockets, a solid fuel and oxidizer
is used.
During combustion, new chemical
substances are created from the fuel and the
oxidizer. These substances are called
exhaust. Most of the exhaust comes from
chemical combinations of the fuel and
26. oxygen. When a hydrogen-carbon-based
fuel (like gasoline) burns, the exhaust
includes water (hydrogen + oxygen) and
carbon dioxide (carbon + oxygen). But the
exhaust can also include chemical
combinations from the oxidizer alone. If the
gasoline is burned in air, which contains 21%
oxygen and 78% nitrogen, the exhaust can
also include nitrous oxides (NOX, nitrogen +
oxygen). The temperature of the exhaust is
high because of the heat that is transferred
to the exhaust during combustion. Because
of the high temperatures, exhaust usually
occurs as a gas, but there can be liquid or
solid exhaust products as well. Soot, for
example, is a form of solid exhaust that
occurs in some combustion processes.
During the combustion process, as the fuel
and oxidizer are turned into exhaust
products, heat is generated. Interestingly,
some source of heat is also necessary to
start combustion. Gasoline and air are both
present in your automobile fuel tank; but
combustion does not occur because there is
no source of heat. Since heat is both
required to start combustion and is itself a
product of combustion, we can see why
27. combustion takes place very rapidly. Also,
once combustion gets started, we don't have
to provide the heat source because the heat
of combustion will keep things going. We
don't have to keep lighting a campfire, it just
keep burning.
For combustion to occur three things must
be present: a fuel to be burned, a source of
oxygen, and a source of heat. As a result of
combustion, exhausts are created and heat
is released. You can control or stop the
combustion process by controlling the
amount of the fuel available, the amount of
oxygen available, or the source of heat.
3.3. Internal Combustion System
Component Overview
An internal combustion engine is a heat
engine where the combustion of a fuel
occurs with air in a combustion chamber that
is an integral part of the working fluid flow
circuit. In an internal combustion engine the
expansion of the high-temperature and high-
pressure gases produced by combustion
apply direct force to some component of the
engine. The force is applied typically to
pistons, turbine blades, rotor or a nozzle.
28. This force moves the component over a
distance, transforming chemical energy into
useful mechanical energy.
The term internal combustion engine usually
refers to an engine in which combustion is
intermittent, such as the more familiar four-
stroke and two-stroke piston engines. A
second class of internal combustion engines
use continuous combustion: gas turbines, jet
engines and rocket engines, which are
internal combustion engines on the same
principle as previously described
Internal combustion engines are quite
different from external combustion engines,
such as steam engines, in which the energy
is delivered to a working fluid not consisting
of, mixed with, or contaminated by
combustion products. Working fluids can be
air, hot water, pressurized water or steam in
a boiler.
Internal combustion engines are usually
powered by energy-dense fuels such as
petrol or diesel, liquids derived from fossil
fuels. While there are many stationary
applications, most Internal combustion
engines are used in mobile applications
such as cars, aircraft, and boats.
29.
30. 3.4. Boiler Water and Steam Cycle
Overview
Boiler or more specifically steam boiler is an
essential part of thermal power plant.
Definition of Boiler
Steam boiler or simply a boiler is basically a
closed vessel into which water is heated until
the water is converted into steam at required
pressure.
Working Principle of Boiler
The basic working principle of boiler is
simple and easy to understand. The boiler is
essentially a closed vessel inside which
water is stored. Fuel (generally coal) is bunt
in a furnace and hot gasses are produced.
These hot gasses come in contact with water
vessel where the heat of these hot gases
transfer to the water and consequently
steam is produced in the boiler. Then this
steam is piped to the steam turbine of
thermal power plant. There are many
different types of boiler utilized for different.
31. Types of Boiler
There are mainly two types of boiler
1. Water tube boiler
2. Fire tube boiler.
Fire Tube Boiler
As it indicated from the name, the fire tube
boiler consists of numbers of tubes through
which hot gasses are passed. These hot gas
tubes are immersed into water, in a closed
vessel. Actually in fire tube boiler one closed
vessel or shell contains water, through which
hot tubes are passed. These fire tubes or hot
gas tubes heated up the water and convert
the water into steam and the steam remains
in same vessel. As the water and steam both
are in same vessel a fire tube boiler cannot
produce steam at very high pressure.
Water Tube Boiler
A water tube boiler is such kind of boiler
where the water is heated inside tubes and
the hot gasses are passed through tubes
which are surrounded by water.
32. 3.5. Generator Overview
An electric generator is a device that
converts mechanical energy obtained from
an external source into electrical energy as
the output.
Generator uses the mechanical energy
supplied to it to force the movement of
electric charges present in the wire of its
windings through an external electric circuit.
This flow of electric charges constitutes the
output electric current supplied by the
generator. This mechanism can be
understood by considering the generator as
a water pump, which causes the flow of
water but does not actually ‘create’ the water
flowing through it.
The modern-day generator works on the
principle of electromagnetic induction the
flow of electric charges could be induced by
moving an electrical conductor, such as a
wire that contains electric charges, in a
magnetic field. This movement creates a
voltage difference between the two ends of
the wire or electrical conductor, which in turn
causes the electric charges to flow, thus
generating electric current.
33.
34. There are two types of generators, one is ac
generator and other is dc generator.
DC Generator
A dc generator converts mechanical energy
into direct current electricity.
A DC generator has the following parts
1. Yoke
2. Pole of
generator
3. Field winding
4. Armature of DC
generator
5. Brushes of
generator
6. Bearing
AC Generator
The working principle of an alternator or AC
generator is similar to the basic working
principle of a DC generator.
Alternating voltage may be generated by
rotating a coil in the magnetic field or by
rotating a magnetic field within a stationary
coil. The value of the voltage generated
depends on-
1. The number of turns in the coil.
2. Strength of the field.
3. The speed at which the coil or magnetic
field rotates.
35. 4. Plant Instrumentation and
Control Theory
Instrumentation is defined as the art and
science of measurement and control of
process variables within a production area.
The process variables used in industries are
Level, Pressure, Temperature, Humidity,
Flow, pH, Force, Speed etc. Control
engineering or control systems engineering
is the engineering discipline that applies
control theory to design systems with
desired behaviours.
The practice uses sensors to measure the
output performance of the device being
controlled and those measurements can be
used to give feedback to the input actuators
that can make corrections toward desired
performance. When a device is designed to
perform without the need of human inputs for
correction it is called automatic control.
Control systems engineering activities focus
on implementation of control systems mainly
derived by mathematical modelling of
systems of a diverse range.
36. 4.1. Instrumentation and Control Overview
Instrumentation is often used to measure
and control process variables within a
laboratory or manufacturing area,
The ability to make precise, verifiable and
reproducible measurements of the natural
world, at levels that were not previously
observable, using scientific instrumentation.
The control of processes is one of the main
branches of applied instrumentation.
Instruments are often part of a control
system in refineries, factories, and vehicles.
Instruments attached to a control system
may provide signals used to operate a
variety of other devices, and to support
either remote or automated control
capabilities. These are often referred to as
final control elements when controlled
remotely or by a control system.
37. 4.2. Temperature Instruments
Temperature is one of the most widely
measured parameters in a power plant. No
matter the type of plant, accurate and
reliable temperature measurement is
essential for operational excellence.
Incorrect measurement because of electrical
effects, nonlinearity or instability can result in
damage to major equipment. Using
advanced diagnostics, modern temperature
instrumentation can inform a plant's
maintenance department that a problem
exists, where it is and what to do about it
long before anyone in operations even
suspects that an issue exists.
Devices for measuring temperature include:
• Thermocouples.
• Thermistors.
• Resistance temperature detector (RTD)
• Pyrometer.
• Infrared.
• Thermometers
4.3. Pressure Measuring Devices
A pressure gauge is a common component
in operations from various industries across
38. the world. But not every gauge is created
equally or made for every situation.
Gauges with bourdon tubes are the most
common pressure measuring devices used
today. They combine a high grade of
measuring technology, simple operation,
ruggedness and flexibility with the
advantages of industrial and cost-effective
production. Needing no external power
supply, bourdon tube gauges are the best
choice for most applications.
Applications for gauges with a bourdon tube
range from highly automated chemical
processes, such as, refineries and
petrochemical processing, to hydraulic and
pneumatic installations. These types of
gauges can also be found at all critical
process monitoring and safety points in
today’s energy industries, from exploration
wells and petrochemical plants, to power
stations and wastewater operations.
A pressure measurement can further be
described by the type of measurement being
performed. The three methods for
measuring pressure are absolute, gauge,
and differential.
39. Absolute Pressure
The absolute measurement method is
relative to 0 Pa, the static pressure in a
vacuum. The pressure being measured is
acted upon by atmospheric pressure in
addition to the pressure of interest.
Therefore, absolute pressure measurement
includes the effects of atmospheric
pressure. This type of measurement is well-
suited for atmospheric pressures such as
those used in altimeters or vacuum
pressures. Often, the abbreviations Paa
(Pascal’s absolute) or psia (pounds per
square inch absolute) are used to describe
absolute pressure.
Gauge Pressure
Gauge pressure is measured relative to
ambient atmospheric pressure. This means
that both the reference and the pressure of
interest are acted upon by atmospheric
pressures. Therefore, gauge pressure
measurement excludes the effects of
atmospheric pressure. These types of
measurements include tire pressure and
blood pressure measurements. Similar to
absolute pressure, the abbreviations Pag
40. (Pascal’s gauge) or psig (pounds per square
inch gauge) are used to describe gauge
pressure.
Differential Pressure
Differential pressure is similar to gauge
pressure; however, the reference is another
pressure point in the system rather than the
ambient atmospheric pressure. You can use
this method to maintain relative pressure
between two vessels such as a compressor
tank and an associated feed line. Also, the
abbreviations Pad (Pascal’s differential) or
PSID (pounds per square inch differential)
are used to describe differential pressure.
4.4. Level Measuring Devices
Level measurement devices can detect,
indicate, and/or help control liquid or solid
levels. Level measurement sensors fall into
two main types. Point level measurement
sensors are used to mark a single discrete
liquid height–a preset level condition.
Generally, this type of sensor functions as a
high alarm, signaling an overfill condition, or
as a marker for a low alarm condition.
Continuous level sensors are more
sophisticated and can provide level
41. monitoring of an entire system. They
measure fluid level within a range, rather
than at a one point, producing an analog
output that directly correlates to the level in
the vessel. To create a level management
system, the output signal is linked to a
process control loop and to a visual
indicator.
Level measurement devices can be used for
continuous monitoring of fluid level, or for
point-level monitoring. In point-level
monitoring they are used to determine if the
fluid level has exceeded a high point, which
could cause a spill, or gone below a low
point, which could mean the system is close
to running on empty.
42. 4.5. Flow Measuring Devices
Flow measurement is the quantification of
bulk fluid movement. Flow can be measured
in a variety of ways. Positive-displacement
flow meters accumulate a fixed volume of
fluid and then count the number of times the
volume is filled to measure flow. Other flow
measurement methods rely on forces
produced by the flowing stream as it
overcomes a known constriction, to
indirectly calculate flow. Flow may be
measured by measuring the velocity of fluid
over a known area.
The most common principals for fluid flow
metering are:
• Differential Pressure Flowmeters
• Velocity Flowmeters
• Positive Displacement Flowmeters
• Mass Flowmeters
• Open Channel Flowmeters
4.6. Introduction to Automated Control
Automation or automatic control, is the use
of various control systems for operating
equipment such as machinery, processes in
factories, boilers, ships, aircraft and other
43. applications with minimal or reduced human
intervention. Some processes have been
completely automated.
The biggest benefit of automation is that it
saves labour; however, it is also used to
save energy and materials and to improve
quality, accuracy and precision.
Automation has been achieved by various
means including mechanical, hydraulic,
pneumatic, electrical, electronic devices and
computers, usually in combination.
Complicated systems, such as modern
factories, airplanes and ships typically use
all these combined techniques
Distributed Control System (DCS)
A distributed control system (DCS) is a
control system for a process or plant,
wherein control elements are distributed
throughout the system. This is in contrast to
non-distributed systems, which use a single
controller at a central location. In a DCS, a
hierarchy of controllers is connected by
communications networks for command and
monitoring.
44. Distributed control systems (DCSs) are
dedicated systems used to control
processes that are continuous or batch-
oriented, such as oil refining,
petrochemicals, power generation, fertilizers
DCSs are connected to sensors and
actuators and use setpoint control to control
the flow of material through the plant. The
most common example is a setpoint control
loop consisting of a pressure sensor,
controller, and control valve. Pressure or
flow measurements are transmitted to the
controller, usually through the aid of a signal
conditioning input/output (I/O) device. When
the measured variable reaches a certain
point, the controller instructs a valve or
actuation device to open or close until the
fluidic flow process reaches the desired
setpoint. Large power plant have many
thousands of I/O points and employ very
large DCSs. Processes are not limited to
fluidic flow through pipes, however, and can
also include things like variable speed drives
and motor control centers, .
DCSs are usually designed with redundant
processors to enhance the reliability of the
control system. Most systems come with
45. displays and configuration software that
enable the end-user to configure the control
system without the need for performing low-
level programming, allowing the user also to
better focus on the application rather than
the equipment. However, considerable
system knowledge and skill is required to
properly deploy the hardware, software, and
applications. Many plants have dedicated
personnel who focus on these tasks,
augmented by vendor support that may
include maintenance support contracts.
DCSs may employ one or more workstations
and can be configured at the workstation or
by an off-line personal computer. Local
communication is handled by a control
network with transmission over twisted -pair,
coaxial, or fiber-optic cable. A server and/or
applications processor may be included in
the system for extra computational, data
collection, and reporting capability.
Automatic Generation Control
In an electric power system, automatic
generation control (AGC) is a system for
adjusting the power output of multiple
generators at different power plants, in
46. response to changes in the load. Since a
power grid requires that generation and load
closely balance moment by moment,
frequent adjustments to the output of
generators are necessary. The balance can
be judged by measuring the system
frequency; if it is increasing, more power is
being generated than used, and all the
machines in the system are accelerating. If
the system frequency is decreasing, more
load is on the system than the instantaneous
generation can provide, and all generators
are slowing down.
47. 5. Intro to Plant Equipment
5.1. Introduction to Pumps
What is a pump?
A pump is a device that moves fluids. Pumps
are selected for processes not only to raise
and transfer fluids, but also to meet some
other criteria. This other criteria may be
constant flow rate or constant pressure.
Pumps are in general classified as
1. Positive Displacement pumps
The centrifugal pump produce a head and a
flow by increasing the velocity of the liquid
through the machine with the help of the
rotating vane impeller. Centrifugal pumps
include radial, axial and mixed flow units.
2. Positive Displacement Pumps
A positive displacement pump operates by
alternating filling a cavity and then displacing
a given volume of liquid. A positive
displacement pump delivers a constant
volume of liquid for each cycle independent
of discharge pressure or head
48. 5.2. Introduction to Valves and Their
Components
Valves are mechanical devices that controls
the flow and pressure within a system or
process. They are essential components of a
piping system that conveys liquids, gases.
Some valves are self-operated while others
manually or with an actuator or pneumatic
or hydraulic is operated.
Functions from Valves are:
• Stopping and starting flow
• Reduce or increase a flow
• Controlling the direction of flow
• Regulating a flow or process pressure
• Relieve a pipe system of a certain
pressure
Regardless of type, all valves have the
following basic parts:
• the body,
• bonnet,
• trim (internal elements)
49. A typically Trim design includes a disk,
seat, stem, and sleeves needed to guide
the stem.
• Valve Disk and Seat
• Valve Stem
• actuator, and packing.:
Classification of Valves
1. Linear Motion Valves.
Gate, globe, diaphragm, and lift Check
Valves, moves in a straight line to allow,
stop, or throttle the flow.
2. Rotary Motion Valves. When the valve-
closure member travels along an angular
or circular path, as in butterfly, ball, plug,
eccentric- and Swing Check Valves,
3. Quarter Turn Valves. Some rotary motion
valves require approximately a quarter
turn, 0 through 90°, motion of the stem to
go to fully open from a fully closed
position or vice versa.
50. 5.3. Heat Exchanger Theory
The general function of a heat exchanger is
to transfer heat from one fluid to another.
The basic component of a heat exchanger
can be viewed as a tube with one fluid
running through it and another fluid flowing
by on the outside. There are thus three heat
transfer operations that need to be
described:
1. Convective heat transfer from fluid to the
inner wall of the tube,
2. Conductive heat transfer through the tube
wall, and
3. Convective heat transfer from the outer
tube wall to the outside fluid.
Heat exchangers are typically classified
according to flow arrangement and type of
construction. The simplest heat exchanger is
one for which the hot and cold fluids move in
the same or opposite directions in a
concentric tube (or double-pipe)
construction. In the parallel-flow
arrangement the hot and cold fluids enter at
the same end, flow in the same direction,
and leave at the same end. In the counter
flow arrangement the fluids enter at opposite
51. ends, flow in opposite directions, and leave
at opposite ends.
52. Shell and Tube Heat Exchanger
A shell and tube heat exchanger is a class of
heat exchanger designs. It is the most
common type of heat exchanger in oil
refineries and other large chemical
processes, and is suited for higher-pressure
applications. As its name implies, this type of
heat exchanger consists of a shell (a large
pressure vessel) with a bundle of tubes
inside it. One fluid runs through the tubes,
and another fluid flows over the tubes
(through the shell) to transfer heat between
the two fluids. The set of tubes is called a
tube bundle, and may be composed of
several types of tubes: plain, longitudinally
finned, etc.
Plate Heat Exchanger
Plate heat exchanger is a type of heat
exchanger that uses metal plates to transfer
heat between two fluids. This has a major
advantage over a conventional heat
exchanger in that the fluids are exposed to a
much larger surface area because the fluids
spread out over the plates. This facilitates
the transfer of heat, and greatly increases
the speed of the temperature change.
53. 5.4. Introduction to Hydraulics
A hydraulic drive system is a drive or
transmission system that uses pressurized
hydraulic fluid to power hydraulic system.
The term hydrostatic refers to the transfer of
energy from flow and pressure, not from the
kinetic energy of the flow.
A hydraulic drive system consists of three
parts:
1. The generator (e.g. a hydraulic pump),
driven by an electric motor
2. Valves, filters, piping etc. (to guide and
control the system);
3. Actuator (e.g. a hydraulic motor or
hydraulic cylinder) to drive the
valves/machines.
Hydraulic valves
These valves can control the direction of the
flow of fluid and act as a control unit for a
system. Classification based on function:
• Pressure control valves (PC Valves)
• Flow control valves (FC Valves)
• Direction control valves (DC Valves)
Classification based on method of activation:
• Directly operated valve
54. • Pilot operated valve
• Manually operated valve
• Electrically actuated valve
• Open control valve
• Servo controlled valves
6. Plant Drawings
Process and Instrumentation Diagrams use
special shapes to represent different types
of equipment, valves, instruments and
pipelines.
6.1. P&ID Basics
Process and Instrumentation Drawing or
P&ID is also known as the mechanical flow
diagram and piping and instrumentation
diagram. A P&ID is a complex
representation of the various units found in a
plant. It is used by people in a variety of
crafts. The primary users of the document
after plant startup are process technicians
and instrument and electrical, mechanical,
safety, and engineering personnel.
Process and Instrument diagrams provide
information needed by engineers to begin
planning for the construction of the plant.
P&ID shows how industrial process
55. equipment is interconnected by a system of
pipelines. P&ID schematics also show the
instruments and valves that monitor and
control the flow of materials through the
pipelines.
56. The Advantages of Process and Instrument
Diagram
• Gives everyone a clear understanding of
the instrument process
• Represents the sequence of all relevant
operations occurring during a process
• Help to identify the scope of the process
and analysis
• Presenting events which occur to the
materials
• Incorporates specifications, standards
and details that go into the design
• Facilitate teamwork and communication
• Shows graphically the arrangement of
major equipment, process lines and main
control loops
6.2. Reading a P&ID
To better understand the process and
instrumentation diagram, you need to
understand the symbols used in the piping
and instrumentation diagram.
Letter and number combinations appear
inside each graphical element and letter
combinations are defined by the ISA
57. standard. Numbers are user assigned and
schemes vary. While some companies use
sequential numbering, others tie the
instrument number to the process line
number, and still others adopt unique and
sometimes unusual numbering systems.
The first letter defines the measured or
initiating variables such as Analysis (A),
Flow (F), Temperature (T), etc. with
succeeding letters defining readout, passive,
or output functions such as Indicator (I),
Recorder (R), Transmitter (T), etc
58. 7. Plant Systems
7.1. Introduction to Combustion Air and
Flue Gas Systems
All fossil fuel burning appliances need ample
air intake and draft to complete the
combustion process in a safe and efficient
manner. Homes have furnaces and water
heaters all requiring ample amounts of
combustion air. Whether one or multiple,
including gas boilers, the same rules apply.
The combustion triangle containing the three
elements required for combustion to take
place. These elements are: fuel, heat
(ignition) and air.
Combustion Air
(1) Air that is supplied to combustion
appliances to be used in the combustion of
fuels and the process of venting combustion
gases. Inadequate combustion air can lead
to dangerous problems.
(2) The duct work installed to bring fresh,
outside air to the furnace and/or hot water
heater. Normally 2 separate supplies of air
59. are brought in: one high (for ventilation) and
one low (for combustion).
60. Flue gas System
Flue gas is the gas exiting to the atmosphere
via a flue, which is a pipe or channel for
conveying exhaust gases from a fireplace,
furnace, boiler or steam generator. Quite
often, the flue gas refers to the combustion
exhaust gas produced at power plants. Its
composition depends on what is being
burned, but it will usually consist of mostly
nitrogen (typically more than two-thirds)
derived from the combustion of air, carbon
dioxide (CO2), and water vapor as well as
excess oxygen (also derived from the
combustion air). It further contains a small
percentage of a number of pollutants, such
as particulate matter (like soot), carbon
monoxide, nitrogen oxides, and sulfur oxides
7.2. Introduction to the Circulating Water
System
All thermal power plants, be they coal fired
or nuclear, use the modified Rankine steam
cycle. The steam exiting from the steam
turbine condenses in a condenser and then
is reused in the steam cycle. Almost all
thermal power plants use a surface
condenser for cooling the steam. The only
61. exception is in a geothermal plant where a
direct contact condenser is used.
In a surface condenser, the steam flows over
a tube bundle. The condenser cooling water
flows through the inside of these tubes. In a
large power plant, the condenser will have
about 15,000 tubes. The heat transfer takes
place through the surface of these tubes.
In a direct contact condenser, cooling water
mixes with the steam. The evaporation of the
water cools and condenses the steam.
The circulating water system consists of an
intake canal, the pumps, piping, cooling
towers and an outfall system.
There are two different systems based on
how the water is sourced and recycled.
Open Cooling system.
In an open circulating water system, water
from a large water body like the sea, or a
river or a lake is pumped to the condenser
and is returned back to the same source.
Since the sea is a free and large open
source of water, we see many power plants
located on the seacoast.
62. Closed Cooling System.
The second is the closed cooling system
where Circulating water is in a closed circuit.
The Circulating water removes the heat from
the condenser and flows to cooling towers.
In the cooling towers an airflow, natural or
forced, cools the water and the water returns
to the condenser. Power plants located
away from large sources of water utilise this
type. The large concrete hyperbolic towers
that you see near thermal power plants are
used for cooling the circulating water.
7.3. Introduction to the Condensate
System
The condensate system cools the exhaust
steam from the turbine which is then
collected in the condenser hot well to be
used again as feed water. The lower the
pressure and temperature that can be
achieved in the condenser, the greater the
overall efficiency of the plant.
Steam condensing
The condenser condenses the steam from
the exhaust of the turbine into liquid to allow
63. it to be pumped. If the condenser can be
made cooler, the pressure of the exhaust
steam is reduced and efficiency of the cycle
increases.
The surface condenser is a shell and tube
heat exchanger in which cooling water is
circulated through the tubes. The exhaust
steam from the low pressure turbine enters
the shell where it is cooled and converted to
condensate (water) by flowing over the
tubes.
For best efficiency, the temperature in the
condenser must be kept as low as practical
in order to achieve the lowest possible
pressure in the condensing steam. Since the
condenser temperature can almost always
be kept significantly below 100 °C where the
vapour pressure of water is much less than
atmospheric pressure, the condenser
generally works under vacuum. Thus leaks
of non-condensible air into the closed loop
must be prevented.
Typically the cooling water causes the steam
to condense at a temperature of about 25 °C
and that creates an absolute pressure in the
condenser of about 2–7 kPa (0.59–2.07
inHg), i.e. a vacuum of about −95 kPa (−28
64. inHg) relative to atmospheric pressure. The
large decrease in volume that occurs when
water vapor condenses to liquid creates the
low vacuum that helps pull steam through
and increase the efficiency of the turbines.
The condenser generally uses either
circulating cooling water from a cooling
tower to reject waste heat to the
atmosphere, or once-through water from a
river, lake or ocean.
The heat absorbed by the circulating cooling
water in the condenser tubes must also be
removed to maintain the ability of the water
to cool as it circulates. This is done by
pumping the warm water from the condenser
through either natural draft, forced draft or
induced draft cooling towers
Another form of condensing system is the
air-cooled condenser. The process is similar
to that of a radiator and fan. Exhaust heat
from the low pressure section of a steam
turbine runs through the condensing tubes,
the tubes are usually finned and ambient air
is pushed through the fins with the help of a
large fan. The steam condenses to water to
be reused in the water-steam cycle. Air-
cooled condensers typically operate at a
65. higher temperature than water-cooled
versions.
From the bottom of the condenser, powerful
condensate pumps recycle the condensed
steam (water) back to the water/steam cycle.
66. 7.4. Introduction to the Feedwater System
The boiler feedwater used in the steam
boiler is a means of transferring heat energy
from the burning fuel to the mechanical
energy of the spinning steam turbine. The
total feed water consists of recirculated
condensate water and purified makeup
water. Because the metallic materials it
contacts are subject to corrosion at high
temperatures and pressures, the makeup
water is highly purified before use. A system
of water softeners and ion exchange
demineralizers produces water so pure that
it coincidentally becomes an electrical
insulator, with conductivity in the range of
0.3–1.0 microsiemens per centimeter.
The feed water cycle begins with
condensate water being pumped out of the
condenser after traveling through the steam
turbines.
The water is pressurized in two stages, and
flows through a series of six or seven
intermediate feed water heaters, heated up
at each point with steam extracted from an
appropriate duct on the turbines and gaining
temperature at each stage. Typically, in the
67. middle of this series of feedwater heaters,
and before the second stage of
pressurization, the condensate plus the
makeup water flows through a deaerator that
removes dissolved air from the water, further
purifying and reducing its corrosiveness.
The water may be dosed following this point
with hydrazine, a chemical that removes the
remaining oxygen in the water to below 5
parts per billion (ppb.)
68. 8. Turbines
What is a turbine?
A turbine is a machine designed to capture
some of the energy from a moving fluid (a
liquid or a gas) The key parts of a turbine are
a set of blades that catch the moving fluid, a
shaft or axle that rotates as the blades move,
and some sort of machine that's driven by
the axle. In a modern wind turbine, there are
typically three propeller-like blades attached
to an axle that powers an electricity
generator. In an ancient waterwheel, there
are wooden slats that turn as the water flows
under or over them, turning the axle to which
the wheel is attached and usually powering
some kind of milling machine.
Impulse turbine
In an impulse turbine, a fast-moving fluid is
fired through a narrow nozzle at the turbine
blades to make them spin around. The
blades of an impulse turbine are usually
bucket-shaped so they catch the fluid and
direct it off at an angle or sometimes even
back the way it came (because that gives the
70. Reaction turbine
In a reaction turbine, the blades sit in a much
larger volume of fluid and turn around as the
fluid flows past them. A reaction turbine
doesn't change the direction of the fluid flow
as drastically as an impulse turbine: it simply
spins as the fluid pushes through and past
its blades. Wind turbines are perhaps the
most familiar examples of reaction turbines.
8.1. Steam Turbine Design
A steam turbine is powered by the energy in
hot, gaseous steam and works like a cross
between a wind turbine and a water turbine.
.Steam turbines use high-pressure steam to
turn electricity generators at incredibly high
speeds, so they rotate much faster than
either wind or water turbines. (A typical
power plant steam turbine rotates at 1800–
3600 rpm) which needs to use a gearbox to
drive a generator quickly enough to make
electricity.) Just like in a steam engine, the
steam expands and cools as it flows past a
steam turbine's blades, giving up as much as
possible of the energy it originally contained.
All steam turbines can be classified into two
categories; extraction (condensing) steam
71. turbine and non-condensing steam turbine
also known as back pressure steam
turbines.
The extraction turbine
The extraction turbine contains two outlets
.The first outlet extracts the steam with
intermediate pressure for the feeding of the
heating process while the second outlet
extracts the remaining steam with low-
pressure steam for the condensation. The
extraction of heat from the first outlet can be
stopped to generate more output. Steam
control valves at this outlet make this steam
very flexible and allow adjusting the output
as per demand. The steam from the second
outlet goes to the condensation chamber
where cooling water brings the temperature
of the steam down. The condensed water
then goes back to the boiler for the
regeneration of the electricity of power,
therefore, it is also known as the
regenerative steam turbine
Back Process Steam Turbine
The non-condensing steam turbine uses
high-pressure steam for the rotation of
blades. This steam then leaves the turbine
72. at the atmospheric pressure or lower
pressure. The pressure of outlet steam
depends on in the load, therefore, this
turbine is also known as the back-pressure
steam turbine. This low-pressure steam
uses for processing and no steam is used for
condensation.
8.2. Steam Turbine Valves and Controls
Steam turbine governing is the procedure of
controlling the flow rate of steam to a steam
turbine so as to maintain its speed of rotation
as constant. The variation in load during the
operation of a steam turbine can have a
significant impact on its performance.
Steam Turbine Governing is the procedure
of monitoring and controlling the flow rate of
steam into the turbine with the objective of
maintaining its speed of rotation as constant.
The flow rate of steam is monitored and
controlled by interposing valves between the
boiler and the turbine.
Throttle governing
Throttle governing the pressure of steam is
reduced at the turbine entry thereby
73. decreasing the availability of energy. In this
method steam is passed through a restricted
passage thereby reducing its pressure
across the governing valve. The flow rate is
controlled using a partially opened steam
control valve. The reduction in pressure
leads to a throttling process in which the
enthalpy of steam remains constant.
74. Nozzle governing
In nozzle governing the flow rate of steam is
regulated by opening and shutting of sets of
nozzles rather than regulating its pressure.
In this method groups of two, three or more
nozzles form a set and each set is controlled
by a separate valve. The actuation of
individual valve closes the corresponding set
of nozzle thereby controlling the flow rate.
Emergency Governing
Emergency governors come into action
under the following condition.
• When the speed of shaft increases
beyond 110%.
• Balancing of the turbine is disturbed.
• Failure of the lubrication system.
• Vacuum in the condenser is quite less or
supply of coolant to the condenser is
inadequate.
75. 8.3. Steam Turbine Auxiliaries
Some of the main auxiliaries of associated
with steam turbine are
Lube-oil System
1. Pumps
The lubricating oil system has three separate
pumps which supply the bearings and
hydraulic system with oil.
• Lube oil Jacking pump – this is used when
the turbine is being rotated by the turning
gear.
• Emergency Lube oil Pump – this cuts in if
the turbine trips through loss of power.
• Main lube oil pump – this pump draws the
oil from a lube oil tank and supplies the
turbine bearings and governor. This is
normally a centrifugal pump driven by the
turbine or generator shaft.
76. 2. L.O. Filters
Some systems have duplex filters on the
suction and discharge pipework of the
pumps, but at a minimum a set on the
discharge. These remove any debris picked
up by the oil before the oil is fed to the
bearings.
3. L.O. Coolers
The oil lubricates the bearings absorbing the
heat from friction. This heat is dissipated by
the coolers. These are usually tube coolers,
water being the medium used to cool the oil.
4. L.O. Centrifuge
The centrifuge is usually positioned above
the lube oil tank and runs continually whilst
the turbine is operating, only coming off line
for cleaning. It draws the lube oil from the
lube oil tank removing any water and
particles by centrifugal force before
discharging the clean oil back to the tank.
5. Turbine Governor
77. 9. Internal combustion Engines
9.1. Combustion Turbine Fundamentals
Combustion Turbines are an essential
component in power production. A
combustion turbine is a simple, but yet a
complex machine. It is simple in terms of its
theory of operation. It is complex in terms its
size, its risk to mis-operation, and the need
to provide complex support and/or protection
schemes. Combustion Turbines are used in
various applications including, simple cycle
peaking plants, or combined cycle
operations.
Internal-combustion engine, one in which
combustion of the fuel takes place in a
confined space, producing expanding gases
that are used directly to provide mechanical
power. Such engines are classified as
reciprocating or rotary, spark ignition or
compression ignition, and two-stroke or four-
stroke; the most familiar combination, used
from automobiles to lawn mowers, is the
reciprocating, spark-ignited, four-stroke
gasoline engine. Other types of internal-
combustion engines include the reaction
78. engine (see jet propulsion, rocket), and the
gas turbine. Engines are rated by their
maximum horsepower, which is usually
reached a little below the speed at which
undue mechanical stresses are developed.
9.2. Introduction to Gas Turbines
A gas turbine, also called a combustion
turbine, is a type of internal combustion
engine.
The basic operation of the gas turbine is
similar to that of the steam power plant
except that air is used instead of water.
Fresh atmospheric air flows through a
compressor that brings it to higher pressure.
Energy is then added by spraying fuel into
the air and igniting it so the combustion
generates a high-temperature flow. This
high-temperature high-pressure gas enters
a turbine, where it expands down to the
exhaust pressure, producing a shaft work
output in the process. The turbine shaft work
is used to drive the compressor and other
devices such as an electric generator that
may be coupled to the shaft. The energy that
is not used for shaft work comes out in the
79. exhaust gases, so these have either a high
temperature or a high velocity. The purpose
of the gas turbine determines the design so
that the most desirable energy form is
maximized.
Gas turbines are used to power aircraft,
trains, ships, electrical generators, and tanks
9.3. Gas Turbines major components
Major components of a gas turbine
Compressor — the compressor is made
up of stages. Each stage consists of
rotating blades and stationary stators or
vanes. As the air moves through the
compressor, its pressure and temperature
increase. The power to drive the
compressor comes from the turbine (see
below), as shaft torque and speed.
Combustor or combustion chamber —
Fuel is burned continuously after initially
being ignited during the engine start.
Turbine — the turbine is a series of bladed
discs that act like a windmill, extracting
energy from the hot gases leaving the
combustor. Some of this energy is used to
drive the compressor.
80.
81. 10. Boilers & Boiler Fuel
Systems
A boiler is a closed vessel in which water or
other fluid is heated. The fluid does not
necessarily boil. The heated or vaporized
fluid exits the boiler for use in various
processes or applications.
Industrial Boilers by Fuel Type
Many classify, or talk about, boilers
according to the fuel they burn. The
possibilities are quite diverse.
Coal: Most industrial boilers burn
pulverized coal.
Biomass encompasses all types of
burnable plant material, such as wood
Gas fired boilers burn natural gas,
which can be a mix of methane,
ethane, propane, butane, or pentane.
Oil: Boilers that burn gasoline, diesel,
or other petroleum-based fluids are
classified as oil-fired boilers
.
82. 10.1. Coal Handling System
In a coal based thermal power plant, the
initial process in the power generation is
“Coal Handling”.
The huge amount of coal is usually supplied
through water ways. The coal is delivered to
the storage yard. The coal is taken from the
unloading site to dead storage by belt
conveyors. The belt deliver the coal to 0m
level to the pent house and further moves to
transfer point.
The transfer points are used to transfer coal
to the next belt. The belt elevates the coal to
breaker house. It consists of a rotary
machine, which rotates the coal and
separates the light dust from it through the
action of gravity and transfer this dust to
reject bin house through belt.
The belt further elevates the coal to another
transfer point and it reaches the crusher
through belt. In the crusher a high-speed 3-
phase induction motor is used to crush the
coal to a size of 50mm so as to be suitable
for milling system. Coal rises from crusher
house and reaches the dead storage by
passing through transfer point.
83. 10.2. Boiler Fuel System
In order for a boiler to convert water to
steam, a fuel source must release its energy
in the form of combustion in the boiler
furnace. Fuel systems play a critical role in
the performance of a boiler. The most
commonly used fuels in power boilers are
natural gas, fuel oil, coal, and wood
(biomass). Each of these fuels have different
physical properties that require delivery
systems that are unique to that fuel. Fuel
systems should be properly operated and
maintained to run efficiently
84. 11. Power Generation
Electricity generation is the process of
generating electric power from other sources
of primary energy. The other processes,
electricity transmission, distribution, and
electrical power storage and recovery using
pumped-storage methods are normally
carried out by the electric power industry.
Electricity is most often generated at a power
station by electromechanical generators,
primarily driven by heat engines fuelled by
chemical combustion or nuclear
11.1. Generator and Auxiliary Systems’
Functions
Auxiliary system equipment is critical to
ensure efficient, reliable and safe operation
of the generator. Time and wear of auxiliary
system components have direct impact on
generator availability
85. Generator Auxiliaries
All large generators require auxiliary
systems to handle such things as lubricating
oil for the rotor bearings, hydrogen cooling
apparatus, sealing oil, demineralized water
for stator winding cooling and excitation
systems for field-current application.
Seal & Lube Oil System
A typical lube oil system provides oil for both
the turbine and generator bearings while
also serving as a source of seal oil to the
generator seals.
Hydrogen Cooling System
Generators operate with hydrogen rather
than air as the internal medium because
hydrogen has less drag for a given thermal
convection capability.
Stator Winding Cooling Water System
The stator cooling water system is used to
remove heat from generator armature bars.
Exciter Systems
A number of different types of excitation
systems are used on large synchronous
86. machines. Within the three main categories,
rotating, static and brushless,
Monitoring/Sensor Systems
• Generator Fan Differential Pressure
Gages and Transmitters.
• Vibration Monitoring Systems
• Generator Condition (Core) Monitors
detect overheating
• Gas Purity Analyzers
• Dew Point Analyzers
• Temperature Sensors
• Gas Dryers
11.2. Generator and Auxiliary Systems’ Flow
Paths and Major Components
An AC generator in its most basic form, has
these components:
• Rotor - an armature wound with wire coils
• Slip Rings - part of the rotor / armature,
connected to the wire coils
• Brushes - part of the frame, ride in contact
with the slip rings
• Field (stator) - magnetic field for the rotor
/ armature. This can be either a permanent
magnet or an electromagnet.
87.
88. The rotating armature spins the wire coils
through the field. The changing (alternating)
field seen by the wires induces a
corresponding alternating current that is
picked up by the brushes from the slip rings.
When an electromagnet is used for the field,
the alternator's output can be regulated by
simply changing the field current. A
feedback system monitors output voltage
and controls the field coil to regulate the
output to the correct voltage.
There are variants on this setup where the
rotor and stator reverse roles. For example,
an automotive alternator supplies DC
current to the rotor through slip rings. The
rotor makes a rotating magnetic field which
induces current in the fixed stator coils,
which in turn makes the AC output. In a car
system this this is then rectified into DC by a
set of diodes, for an AC system the current
is taken as-is.
The "rotating bridge" (brushless) style of AC
generator couples AC to the rotor through a
rotary transformer to power the rotating field.
This AC is then rectified into DC right on the
rotor by a bridge diode set, which then
energizes the rotor coils. The energized
89. rotor makes a rotating field which is then
picked up the the stator coils as AC.
11.3. Environmental Protection
The Clean Power Plan will reduce carbon
pollution from power plants, the nation’s
largest source, while maintaining energy
reliability and affordability.
11.4. Flue Gas Desulfurization System
Flue-gas desulfurization (FGD) is a set of
technologies used to remove sulfur dioxide
(SO2) from exhaust flue gases of fossil-fuel
power plants, and from the emissions of
other sulfur oxide emitting processes.
Methods
As stringent environmental regulations
regarding SO2 emissions have been
enacted in many countries, SO2 is now
being removed from flue gases by a variety
of methods. Below are common methods
used:
• Wet scrubbing using a slurry of alkaline
sorbent, usually limestone or lime, or
seawater to scrub gases;
90. • Spray-dry scrubbing using similar sorbent
slurries;
• Wet sulfuric acid process recovering
sulfur in the form of commercial quality
sulfuric acid;
• SNOX Flue gas desulphurisation removes
sulfur dioxide, nitrogen oxides and
particulates from flue gases;
• Dry sorbent injection systems.
For a typical coal-fired power station, flue-
gas desulfurization (FGD) may remove 90
percent or more of the SO2 in the flue gases.
91. 12. Electrical Systems and
Equipment
An electric power system is a network of
electrical components used to supply,
transfer and use electric power. An example
of an electric power system is the network
that supplies a region's homes and industry
with power—for sizeable regions, this power
system is known as the grid and can be
broadly divided into the generators that
supply the power, the transmission system
that carries the power from the generating
centres to the load centres and the
distribution system that feeds the power to
nearby homes and industries. Smaller power
systems are also found in industry, hospitals,
commercial buildings and homes. The
majority of these systems rely upon three-
phase AC power—the standard for large-
scale power transmission and distribution
across the modern world.
92. 12.1. Protection Relays
The objective of power system protection is
to isolate a faulty section of electrical power
system from rest of the live system so that
the rest portion can function satisfactorily
without any severer damage due to fault
current.
Actually circuit breaker isolates the faulty
system from rest of the healthy system and
this circuit breakers automatically open
during fault condition due to its trip signal
comes from protection relay. The main
philosophy about protection is that no
protection of power system can prevent the
flow of fault current through the system, it
only can prevent the continuation of flowing
of fault current by quickly disconnect the
short circuit path from the system. For
satisfying this quick disconnection the
protection relays should have following
functional requirements.
12.2. Generator, Transformer and Motor
Protection
A generator is subjected to electrical traces
imposed on the insulation of the machine,
93. mechanical forces acting on the various
parts of the machine, and temperature rises.
These are the main factors which make
protection necessary for the generator or
alternator. Even when properly used, a
machine in its perfect running condition does
not only maintain its specified rated
performance for many years, but it does also
repeatedly withstand certain excess of over
load.Hence, preventive measures must be
taken against overloads and abnormal
conditions of the machine so that it can serve
safely. Despite of sound, efficient design,
construction, operation, and preventive
means of protection, the risk of that fault
cannot be completely eliminated from any
machine.The devices used in generator
protection, ensure the fault, made dead as
quickly as possible.
The various forms of protection applied to
the generator can be categorized into two
manners,
1. Protective relays to detect faults occurring
outside the generator.
2. Protective relays to detect faults occurring
inside the generator.
94. 12.3. Grounding and Bonding
Earthing and Grounding are actually
different terms for expressing the same
concept. Ground or earth in a mains
electrical wiring system is a conductor that
provides a low impedance path to the earth
to prevent hazardous voltages from
appearing on equipment.
Bonding is simply the act of joining two
electrical conductors together. These may
be two wires, a wire and a pipe, or these may
be two Equipments.
Earthing means connecting the dead part (it
means the part which does not carries
current under normal condition) to the earth
for example electrical equipment’s frames,
enclosures, supports etc. The purpose of
earthing is to minimize risk of receiving an
electric shock if touching metal parts when a
fault is present. Generally green wire is used
.
12.4. Main Transformers
Generation Transformer is employed in
power plant for stepping up the voltage for
transmitting the power to the grid. Electrical
power is generated in the power plant at
95. lower voltages (typically generation voltage
will be between 11kV to 33kV). In order to
transmit the power to long distances voltage
has to step up to reduce the losses. Rating
of the generation transformers will be almost
equal to the rating of the generator (500MW
generating unit will have generating
transformer rating about 588MVA).
Connection between the generator
transformer and power plant generator will
be through isolated Phase Bus Duct (IPBD).
96. Unit auxiliary Transformer (UAT):
Power plant is provided with Unit Auxiliary
Transformers (UAT) connected to the
generator terminals through Isolated Phase
Bus Duct (IPBD). Unit Auxiliary
Transformers provides electrical power to
power plant distribution buses by stepping
down the voltage from 11kV to 6.6kV
Station Service Transformer
Station Transformers are employed for
supplying power to plant auxiliary loads
during the event of starting of the plant or
when generating unit is not generating
power. Station Transformers are connected
to the swichyard bus. LV side of the station
transformer is connected to the auxiliary
load buses.Station transformer is normally
rated for supplying power to the auxiliary
loads. On-load tap changing mechanism is
provided to regulate the terminal voltage of
the transformer.
Auxiliary Transformers
These transformers are employed in the
power plants for delivering power to low
voltage loads (voltage below 1kV). These
97. transformers connects between HV
distribution buses and LV distribution buses
of the plant. Their rating will be around 1 to
5MVA. Natural oil cooling or air cooled
transformers are used.
12.5. Fuses and Circuit Breakers
A circuit breaker is an automatically
operated electrical switch designed to
protect an electrical circuit from damage
caused by overcurrent or overload or short
circuit. Its basic function is to interrupt
current flow after protective relays detect a
fault. Unlike a fuse, which operates once and
then must be replaced, a circuit breaker can
be reset (either manually or automatically) to
resume normal operation. Circuit breakers
are made in varying sizes, from small
devices that protect an individual household
appliance up to large switchgear designed to
protect high voltage circuits
A fuse interrupts an excessive current so
that further damage by overheating or fire is
prevented. Wiring regulations often define a
maximum fuse current rating for particular
circuits. Overcurrent protection devices are
essential in electrical systems to limit threats
98. to human life and property damage. The time
and current operating characteristics of
fuses are chosen to provide adequate
protection without needless interruption.
Slow blow fuses are designed to allow
harmless short term currents over their
rating while still interrupting a sustained
overload. Fuses are manufactured in a wide
range of current and voltage ratings to
protect wiring systems and electrical
equipment.
99. 13. Steam Tables
A complete set of steam tables is available,
consisting of the five regions from sub-
saturated water through to superheated
steam.
Sub Saturated Water Region
Saturated Water Line
Wet Steam Region
Dry Saturated Steam Line
Superheated Steam Region
13.1. Understanding the Basic Properties of
Water and Steam
While the properties of water at atmospheric
pressure are commonly known, water under
different pressures will exhibit different
properties. When water is boiled at
pressures higher than atmospheric, the
same events occur as described above with
two exceptions. First, the boiling
temperature will be higher than 100°C.
Second, less latent heat is required to be
added to change the water completely into
steam. If water were to be boiled at a
pressure lower than atmospheric pressure,
100. then we would find that the boiling
temperature would be less than 100°C and
a larger amount of latent heat would be
required to change the water completely into
steam.
When water is below the boiling point, the
addition of heat is seen as sensible heat.
This water is said to be a subcooled liquid
when water is below the boiling point, the
addition of heat is seen as sensible heat.
This water is said to be a subcooled liquid.
When enough sensible heat is added so that
the temperature of the water approaches
saturation temperature but no steam has yet
been formed, the water is said to be a
saturated liquid. When enough sensible heat
is added so that the temperature of the water
approaches saturation temperature but no
steam has yet been formed, the water is said
to be a saturated liquid.
As the water is transformed from a saturated
liquid to saturated steam, boiling is
occurring. As latent heat is added, the
temperature of the water remains the same
but the saturated liquid is being changed into
a saturated vapor. During this period the
water is referred to as a liquid/vapor mixture.
101. When enough latent heat is added so that all
of the liquid is converted into vapor, the
water becomes a saturated vapor. Note that
the saturated vapor is 100% vapor and
exists at the same temperature as the
saturated liquid. Above the saturated steam
point, vapor exists at a temperature higher
than saturation temperature. This is the
superheated vapor region.
Once the boiling point is reached, the water’s
temperature ceases to rise and stays the
same until all the water is vaporized. The
water goes from a liquid state to a vapour
state it receives energy in the form of “latent
heat of vaporization”. As long as there’s
some liquid water left, the steam’s
temperature is the same as the liquid
water’s. Steam is then called saturated
steam.
When all the water is vaporized, any
subsequent addition of heat raises the
steam’s temperature. Steam heated beyond
the saturated steam level is called
superheated steam.
102. 14. Basic Water Chemistry
and Treatment
Services for power plant and boiler water
chemistry
The water-steam circuit boilers are very
fickle systems. The most commonly faced
problems are caused by corrosion,
sedimentation and other challenges typical
for water chemistry. This can be the result of,
for instance, sub-standard quality of return
condensate, incorrect chemical program,
insufficient sampling and supervision, or
simply poor processing.
Examples of power plant chemistry services
solving immediate water chemistry
problems
assessing water-steam circuits
determining the power plant’s own control
system
Demineralization Plant
The function of demineralization plant is to
remove dissolved salt by ion exchange
method (chemical method) and there by
producing pure feed water for boiler.
103. 14.1. Corrosion Control in a Power Plant
Power plants have to increase efficiencies,
lower costs and reduce the amount of time
offline for maintenance, corrosion prevention
techniques will help lengthen the life of
various components and increase safety.
While many thermal power plants share the
same types of corrosion issues, some
require different preventive approaches
Common Types of Corrosion
Oxide corrosion: An electrochemical
process that occurs when metal is
exposed to water and changes in
composition.
Galvanic corrosion: A process that
occurs when two dissimilar metals
contact each other; the resulting
electrical reaction leads to and
accelerates corrosion.
Erosion: The result of an aggressive
chemical environment combined with
high fluid surface velocities that
104. ultimately wear away a surface’s
protective scale or coating.
14.2. Corrosion Control in a Power Plant
Generators: Maintain low humidity levels
of 35 percent or lower using a closed-
loop system.
Pipes: Install insulation with a jacket or
protective coating, replace pipes with
more resistant materials or improve the
piping design so it has better flow
geometries.
Water chemistry changes: When
chemicals or organic agents in the water
(e.g., anaerobic bacteria) lead to
corrosion, a water-conditioning agent
may be helpful. Replacing steel
components with composite lines may
also be effective, particularly in nuclear
plants.
Turbines: Seal openings as tightly as
possible.
Controlling water and steam: Use drains
or vacuums to prevent water pooling.
105. Dehumidifiers are good for air that
passes through a turbine, drying pockets
of water and reducing relative humidity
(rH) levels.
Oil-fired boilers: Use an open system
and a dehumidifier to dry the air to 20
percent rH after shutting down a boiler.
Protective coatings: Use protective
coatings on components exposed to
water, the outside environment, or in
areas that may experience condensation
or moisture. Protective coatings or
surfaces are also helpful for preventing
erosion-related wear.
Cooling stacks: Install a windshield or
protective liner to prevent chemical
attacks and thermal shock.
Inspections: Regularly inspect and test
components that are at risk for corrosion,
even if they have protective surfaces.
Such components include turbines,
ducts, pipes, welded areas, areas with
demineralize water and scrubber
modules.
Water is essential to running a power plant.
At the same time, water can cause vital
106. components to fail when the materials
oxidize. By preventing and controlling
erosion at a plant, you’ll reduce maintenance
costs and downtime, improve performance
and increase worker safety.
