Advanced energy engineering ktu module 1

ME 403 Advanced Energy
Engineering
Module-I
Rajesh Kumar R
Associate Professor,
Dept. of Mechanical Engg.,
SNGCE, Kadayiruppu.

Power
 Power is the rate of doing work, which equals energy per time.
The units of power are watts, joules per second, and
horsepower .
1 Watt = 1 Joule per second
1 Kilowatt = 1000 Watts
1 Megawatt = 1000 kilowatts = 1341.02 horsepower
 Prime mover is a machine that transforms energy from thermal or
pressure form to mechanical form; typically an engine or turbine.
 A power station (also referred to as a generating station, power
plant, powerhouse, or generating plant) is an industrial facility
for the generation of electric power.

Sources of power
1. Renewable power sources – Renewable energy is obtained from
sources that are essentially inexhaustible.
2. Non-renewable power sources – Non-renewable energy is
obtained mostly from fossil fuels such as coal, oil and gas which
are likely to deplete with time.
Two main sources of power
Sources of power
Non-renewable power sources
Nuclear
Coal Oil Natural gas
Renewable power sources
Wind Geothermal
Solar Tidal
Hydro power Biomass

Comparing renewable and non-
renewable power sources
Renewable resources Non-renewable resources
Present in the atmosphere of the
earth.
Found in the underground of the
earth.
Are replaced by nature itself in a
very short period.
Not replaced.
The renewable energy resources are
abundant in nature.
The non-renewable resources are
scarce resources and not in
abundant in nature.
The renewable resources are
obtained free of cost.
Are very costly and not easily
available.
The renewable resources do not
affect the environment.
Seriously affect the
environment.

Sources of power in Kerala
Sl.No Name of Station Installed Capacity (MW)of station
1 Idukki 6 x 130 780
2 Sabarigiri 4 x 55 + 2x 60 340
3 Idamalayar 2 x 37.5 75
4 Sholayar 3x18 54
5 Pallivasal 3 x 5+ 3x7.5 37.5
6 Kuttiyadi 3x25 75
7 Kuttiyadi Extension 1x50 50
8 Kuttiyadi Additional Extension Scheme 2x50 100
9 Panniar 2 x 16.2 32.4
10 Neriamangalam 3 x17.55 52.65
11 NES 1x25 25
12 Lower Periyar 3 x 60 180
13 Poringalkuthu 4x9 36
14 PLBE 1x16 16
15 Sengulam 4 x 12.8 51.2
16 Kakkad 2x25 50
Sub Total (HEP) 49 Nos 1954.75
Hydel power plants in Kerala

Small hydel power plants in Kerala
Sl.No Name of Station
Installed Capacity (MW)of station
Nos MW
1 Kallada 2x7.5 15
2 Peppara 1x3 3
3 Malankara 3x3.5 10.5
4 Madupatty 1x2 2
5 Malampuzha 1x2.5 2.5
6 Lower Meenmutty (1x0.5 + 2x1.5) 3.5
7 Chembukadavu - 1 3x0.9 2.7
8 Chembukadavu - 2 3x1.25 3.75
9 Urumi -1 3x1.25 3.75
10 Urumi -2 3x0.8 2.4
11 KTR 3x1.25 3.75
12 Poozhithode 3 x 1.6 4.8
13 Ranni-Perinadu 2x2 4
14 Peechi 1x1.25 1.25
15 Vilangad 3x2.5 7.5
16 Chimmony 1x2.5 2.5
17 Adyanpara 2x1.5 +0.5 3.5
Sub Total (SHEP) 31Nos 76.4
Total (Hydel) 80 Nos 2031.15

Thermal power plants in Kerala
SL. No. Name of Station
Installed Capacity (MW)of station
Nos MW
1
BDPP (Brahmapuram Diesel
Power Plant)
3x21.32 63.96
2
KDPP (Kozhikode Diesel
Power Project)
6x16 96
Sub Total (Thermal) 13 nos. 159.96
Wnid/ Solar
1 Kanjikode Wind Farm 9x0.225 2.025
2 Kanjikode Solar plant 1
TOTAL (KSEB)
102 Nos 2194.135

IPP(Independent Power Producer)/CPP
(Captive Power plants)
SL. No.
Name of Station Installed Capacity (MW)of station
Nos MW
1 Maniyar 3x4 12
2 Kuthungal 3x7 21
3 Ullunkal 2x3.5 7
4 Iruttukanam 3 x 1.5 4.5
5 Karikkayam 10.5
6 Mankulam 0.11
7 Meenvallom 3
8 Kallar 0.05
Sub Total 58.16

Load curves
9
A typical daily load curve of a power station
Hour
Load
in
MW
2
4
6
8
10
12 2 4 6 8 10 12 2 4 6 8 10 12
Mid night Noon
 The curve showing the variation of load on the power station with
respect to time is known as a load curve.
 The load on a power station is never constant; it varies from time
to time. These load variations during the whole day (i.e., 24
hours) are recorded half-hourly or hourly and are plotted against
time on the graph.
 The curve thus obtained is known as daily load curve as it
shows the variations of load with respect to time during the day.

Load curves
10
Important terms and factors used in association with load curve.
Maximum demand
Demand factor
Connected load

1. Connected load – It is the sum of continuous ratings of all the
equipments connected to supply system. For instance, if a
consumer has connections of five 100-watt lamps and a power
point of 500 watts, then connected load of the consumer is 5 100 +
500 = 1000 watts.
2. Maximum demand – It is the largest demand of load on the
power station during a given period.
3. Demand factor – It is the ratio of maximum demand on the power
station to its connected load.
The value of demand factor is usually less than 1.

Load curves
11
4. Average load – The average of loads occurring on the power
station in a given period (day or month or year) is known as
average load or average demand.
 
.
24
No of units kWh generated in a day
Daily average load
hours

 
.
No of units kWh generated in a month
Monthly average load
Number of hours in a month

 
.
8760
No of units kWh generated in a year
Yearly average load
hours


Load curves
12
5. Load factor (LF) – The ratio of average load to the maximum
demand during a given period is known as load factor, i.e.,
If the plant is in operation for T hours,
Load factor is always less than 1 because average load is
smaller than the maximum demand.
6. Diversity factor – The ratio of the sum of individual maximum
demands to the maximum demand on power station is known as
diversity factor, i.e.,
.
Average load
Load factor
Max demand

.
Average load T
Load factor
Max demand T



.
.
Sum of individual max demands
Diversity factor
Max demand on power station


Load curves
13
7. Plant capacity factor – Plant factor or plant capacity factor
or capacity factor is the ratio of actual energy produced to the
maximum possible energy that could have been produced during a
given period, i.e.,
Thus if the considered period is one year,
The plant capacity factor is an indication of the reserve capacity
of the plant. A power station is so designed that it has some
reserve capacity for meeting the increased load demand in
future.
Reserve capacity = Plant capacity – Max. demand
.
Actual energy produced
Plant capacity factor
Max energy that could have been produced
Average demand
Plant capacity


8760
Annual kWh output
Annual plant capacity factor
Plant capacity



Load curves
14
8. Plant use factor – It is ratio of kWh generated to the product of
plant capacity and the number of hours for which the plant was in
operation, i.e.,
Suppose a plant having installed capacity of 20 MW produces
annual output of 7·35 106 kWh and remains in operation for
2190 hours in a year. Then,
Station output in kWh
Plant use factor
Plant capacity Hours of use


 
6
3
7.35 10
0.167 16.7%
20 10 2190
Plant use factor =

 
 


Load curves
15
9. Units generated per annum – It is often required to find the
kWh generated per annum from maximum demand and load
factor. The procedure is as follows.
.
Average load
Load factor
Max demand

.
Average load Max demand Load Factor
  
/ ( )
Units generated annum Average load in kW Hours in a year
 
. ( ) 8760
Max demand in kW Load Factor
  

Load duration curve
16
When the load elements of a load curve are arranged in the order
of descending magnitudes, the curve thus obtained is called a
load duration curve.
12 4 8 12 16 20 24
Load
in
MW
0
5
10
15
20
25
Mid night Time of day
a) Load curve
12 4 8 12 16 20 24
Load
in
MW
0
5
10
15
20
25
Hours duration
b) Load duration curve

Types of loads
17
 A device which taps electrical energy from the electric power
system is called a load on the system. The various types of loads
on the power system are as follows.
1. Domestic load – Domestic load consists of lights, fans,
refrigerators, heaters, television, small motors for pumping
water, etc.
2. Commercial load – Commercial load consists of lighting for
shops, fans and electric appliances used in restaurants, etc.
3. Industrial load – Industrial load consists of load demand by
industries.
4. Municipal load – Municipal load consists of street lighting,
power required for water supply and drainage purposes.
5. Irrigation load – This type of load is the electric power
needed for pumps driven by motors to supply water to fields.
6. Traction load – This type of load includes tram cars, trolley
buses, railways, etc. This class of load has wide variation.

Power plants
 A power plant may be defined as a machine or assembly of equipments
that generates electric power.
Peak load plant
1. Gas turbine power plant
2. Diesel power plant
3. Pump storage
Load duration curve
LF = Load Factor
Time as percentage of year
Annual load duration curve showing loads
allocated to different plants
Load
(%)
Run of river plants (100% LF)
Nuclear power plants (90% LF)
Hydro power plants (70% LF)
Steam power plants (60% LF)
Hydro power
plants with limited
storage (40% LF)
(10% LF)
100
80
60
40
20
0
 Power plants are of two types.
1. Stationary power plants
2. Mobile power plants.
 Stationary power plants are
further classified as follows.
1. Base load power plants –
These systems have more
than 5000 full power hours
per year (365 days 24 hours
= 8760 hours) and capacity
factor of more than 57%.
2. Intermediate load power plants – Power plants that average more
than 200 hours but less than 500 full power house hours and a
capacity factor between 23% and 57%.

Power plants
Peak load plant
1. Gas turbine power plant
2. Diesel power plant
3. Pump storage
Load duration curve
LF = Load Factor
Time as percentage of year
Annual load duration curve showing loads
allocated to different plants
Load
(%)
Run of river plants (100% LF)
Nuclear power plants (90% LF)
Hydro power plants (70% LF)
Steam power plants (60% LF)
Hydro power
plants with limited
storage (40% LF)
(10% LF)
100
80
60
40
20
0
3. Peak load power plants – These
power plants are operated only to
meet the power demands at a time of
maximum demand. usually these
units have, less than 2000 hours of
full power hours and have a capacity
factor less than 23%.
4. Central power plants – Generate
electric power or general sale to all
consumers (public, business and
industry, etc.). These plants are set
up by state electricity boards, state
and public governments, public
sector organizations, etc.
5. Captive power plants – These power
plants are setup and operated by
manufacturing companies for their
own use.

Power plants-Module-I
1.Steam power plant
2.Hydel power plant
3.Nuclear power plant
4.Gas turbine power plant
5.Diesel power plant

Steam power plant
A steam power plant using steam as working substance works
basically on Rankine cycle. A steam power plant converts the
chemical energy of the fossil fuels (coal, oil, gas) into
mechanical/electrical energy.
Condenser
Pump
Turbine
Rankine cycle
Boiler

Steam power plant
Layout of a steam power plant
Turbine
Condenser
Pump
Ash storage yard Flue gases
Coal/oil
Boiler with
super-heater
Steam
Feed pump
Feed water
Air
Generator
Air
Cooling
tower
Economiser
Air-preheater
To atmosphere
Chimney
Flue gases
Flue gases

Components of steam power plant
1. Boiler – Boiler is an equipment to produce steam.
2. Steam turbine – High pressure super heated steam is fed to the steam turbine which
causes turbine blades to rotate. Energy in the steam is converted into mechanical energy in
the steam turbine which acts as the prime mover.
3. Generator – It is coupled with the turbine rotor and converts the mechanical energy of the
turbine to the electrical energy.
4. Condenser – Condenser is a heat exchanger in which cooling water is circulated through
the tubes. The exhaust steam from turbine enters the condenser where it is cooled and
converted to condensate (water). The use of condensers improves the efficiency of the power
plant by decreasing the exhaust pressure of the steam below the atmospheric pressure.
The deposition of the salt in the boiler is prevented with the use of condensate instead of
using feed water from outer source which may contain salt. The use of condensers reduces
the capacity of the feed water cleaning system. Water circulating through the condenser
may be taken from the various sources such as river, or lake. If sufficient quantity of water
is not available the hot water coming out of the condenser may be cooled in cooling towers
and circulated again through the condenser.
5. Economizers – Economizers are devices fitted to a boiler which saves energy by using the
heat energy of exhaust gases from the boiler to preheat the feed water thereby improving
the boiler's efficiency.

Components of steam power plant
5. Super-heater – Super-heater is a device that heats the steam generated by the
boiler again increasing its thermal energy. It converts wet steam into superheated
steam (high temperature dry steam).
6. Precipitator – Precipitator is a device (dust collector) that removes particles from
the flowing gas.
7. Air pre-heater or air heater – Air pre-heater is used to recover the heat from the
boiler exhaust gases which increases the thermal efficiency of the boiler by
reducing the useful heat lost in the exhaust gases.
8. Deaerator – It is a device used for the removal of air and other dissolved gases
from the feed water to steam generating boilers. A steam generating boiler requires
that the boiler feed water should be devoid of air and other dissolved gases,
particularly corrosive ones, in order to avoid corrosion of the metal.
9. Forced and induced draught fans – The small pressure difference which causes
a flow of gas to take place is termed as a draught. In a forced draught draught
system, the draught is produced by a fan or a blower installed at the base of the
boiler forces the air through the furnace, flues, air pre-heater, economizer, etc. It is
a positive pressure draught. In induced draught system, a fan or blower is
located at or near the base of the chimney creating a partial vacuum so that the
products of combustion pass up the chimney.

Various circuits in a steam power plant
1. Coal and ash circuit – The coal from the storage is fed to the boiler through coal
handling equipments such as belt conveyors. Heat produced by the burning of
coal is utilized in converting water contained in boiler drum into steam at
suitable pressure and temperature. Ash resulting from combustion of coal is
removed to the ash storage yard through ash handling equipment.
2. Air and gas circuit – Air taken in from atmosphere through the action of a
forced draught (air forced to flow in by the use of blower) or induced draught
(air flowing in due to decreased pressure) fan first passes 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 economizer (economizer capture the
waste heat from flue gas and transfer it to the boiler feed-water), air pre-heater
and finally they are exhausted to the atmosphere through the chimney.
3. Feed water and steam circuit – The steam generated in the boiler is supplied to
the turbine to develop mechanical power. The steam coming out of turbine is
condensed in the condenser and fed back to the boiler using feed pump. Some of
the steam and water is lost by passing through the different components.
Therefore it is necessary to supply 4 to 5 % of total feed water from external
source to compensate the loss.
4. Cooling water circuit – Abundant quantity of water is required for condensation
of steam. This is mostly taken from river. If adequate quantity of water is not
available at the plant site, a cooling tower is used.

Advantages of steam power plant
1. Less initial cost as compared to other generating plants.
2. The capital cost is low compared to hydel plant.
3. Construction time is low.
4. Power generation does not depend on nature’s climatic condition.
5. Power plant can be located near industrial areas.
6. The fuel used is quite cheap.
7. It can be installed at any place irrespective of the existence of coal.
8. It requires less space as compared to Hydro power plants.
9. Cost of generation is less than that of diesel power plants.
10. Steam power plants are most economical if sited near coal mines and by the
side of river or canal.
Disadvantages of steam power plant
1. Source of fuel i.e., coal reserve all over the world is considered to be fixed and
therefore coal mines are being exhausted. Hence, there is a limit in source of
power.
2. Power generation cost is considerably high compared to hydal plant.
3. Operating cost is more compared to diesel and nuclear power plant.
4. Maintenance cost is high as compared with that of hydro and diesel power
plants.
5. Fuel transportation and handling are difficult.

32
Dam
Water carrying
pipe
Reservior
Anchor
T
r
a
n
s
m
i
s
s
i
o
n
l
i
n
e
Transmitting
Tower
Transformer room
Control room
Generator
Turbine
Outlet
Tail race
Transformer
Trash rack
Layout of a hydro electric power plant
Hydro power plant

33
Hydraulic power
P g ρ Q H
   
 
9.81
W Q H η t kWh
    
The electrical energy produced in kWh is expressed as follows
; where, t is the operating time in hours (8760 h/year)
and is the efficiency of the turbine-generator assembly.


34
Components of hydel power plant
1. Catchment area – Whole area behind the dam, draining into
a stream or river across which the dam has been built.
2. Reservoir –The purpose of the storing of water in the
reservoir is to get a uniform power output throughout the
year. A reservoir can be either natural or artificial.
3. Dam – A dam is any barrier that holds water; the water
stored behind the dam is used to drive turbines that are
connected to electrical generators. It acts as an artificial
reservoir.
Based on structure and design, dams are classified as
gravity dams, arch dams and buttress dams.

35
Types of dams
Buttress dam
Arch dam
Gravity dam
1. Gravity dams –Gravity dams rely on their own weight to
hold back large volumes of water.
2. Arch dams – An arch dam is curved in plan, with its
convexity towards the upstream side. eg. Idukki dam.
3. Buttress dam – A buttress dam is a dam with a solid,
water-tight upstream side that is supported at intervals on
the downstream side by a series of buttresses or supports.

36
Dam
Tunnel
Surge tank
Penstock
Power house
Reservoir
Surge tank
4. Penstock – It is pipe carrying water from the surge tank to
the turbine. This is made of steel or concrete.
5. Spillway – The function of spillway is to release surplus
water from the reservoir in order to prevent the possible
failure of the dam.
6. Trash rack – The function of trash rack is to prevent the flow
of debris, sand and fishes to the turbine.
7. Surge tank – It is a storage reservoir used to absorb the
sudden rises of water pressure, as well as to provide extra
water during a drop in water pressure.

37
8. Turbine – The function of turbine is to act as a prime mover to
convert the potential energy of water in to mechanical energy.
It is explained in a later section in detail.
9. Runner – The runner is a circular wheel on which a series of
curved vanes are mounted. Vanes are so designed that water
enters and leaves the runner without shock.
10.Power house – The powerhouse accommodates prime mover,
generator (generate electrical power using mechanical power
obtained from the turbine), accessories and control room
sometimes transformer also. Water after passing through the
turbine is discharged into a downstream called as tailrace,
which carries it into the river.

38
Classification hydro electric power plants
1. Classification with respect to quantity of water available
a) Run-off river plants – Run-of-the-river hydroelectric harvest the
energy from flowing water to generate electricity in the absence of
a large dam and reservoir.
b) Reservoir plants – A reservoir plant is that which has a reservoir
of such size as to allow carrying over storage from wet season to
the next dry season.
2. Classification according to availability of water head
a) High-head hydro-electric plants (head more than 250 m)
b) Medium-head hydro-electric plants (head ranges from 60 m –
250 m)
c) Low-head hydro-electric plants (head ranges from 60 m – 250 m)
3. Classification according to nature of load
a) Peak load plants – The peak load plants are used to supply
power at the peak demand phase.
b) Base load plants – A base load power plant is one that provides a
steady flow of power regardless of total power demand.

39
Selection of site for a hydro power plant
1. Water available – The most important aspect of hydro-electric plant is the availability
of water at the site since all other designs are based on it. Therefore the run-off data at
the proposed site must be available.
2. Water-storage – The output of a hydropower plant is not uniform due to wide
variations of rain fall. To have a uniform power output, water storage is needed so that
excess flow at certain times may be stored to make it available at the times of low flow.
To select the site of the dam ; careful study should be made of the geology and
topography of the catchment area to see if the natural foundations could be found and
put to the best use.
3. Head of water – In order to generate a requisite quantity of power it is necessary that
a large quantity of water at a sufficient head should be available. The level of water in
the reservoir for a proposed plant should always be within limits throughout the year.
4. Distance from load center – Most of the time the electric power generated in a hydro-
electric power plant has to be used some considerable distance from the site of plant.
For this reason, to be economical on transmission of electric power, the routes and the
distances should be carefully considered since the cost of erection of transmission lines
and their maintenance will depend upon the route selected.
5. Access to site – It is always a desirable factor to have a good access to the site of the
plant. This factor is very important if the electric power generated is to be utilized at or
near the plant site. The transport facilities must also be given due consideration.

40
Hydrologic cycle
Hydrologic cycle
Transpiration
from vegetations
Precipitation
(Rain, snow, etc. )
Evaporation
Water table
Percolation
Snow, etc.
Ocean
The hydrologic cycle, also known as the water cycle describes the circulation of water in the
earth-atmosphere system.
1. Precipitation – It includes all the water that falls from atmosphere to earth surface.
Precipitation is of two types, viz., liquid precipitation (rain fall) and solid precipitation
(eg. snow).
2. Run-off – Run-off is the part of water cycle that is flows over the land as surface water
instead of being infiltrated into soil or evaporating.
a) Surface runoff is that portion of rainfall which enters the stream immediately after the
rainfall.
b) Sub-surface runoff is that part of rainfall, which first reaches into the soil and moves
laterally without joining the water - table to the streams, rivers or oceans.
c) Base flow is that part of rainfall which after falling on the ground surface which get
infiltrated into the soil and meets the water table (level below the surface of the
ground where water can be found) and flow to the streams oceans, etc.
Runoff = Surface runoff + Base flow (Including sub - surface runoff)

41
Hydrologic cycle
Hydrologic cycle
Transpiration
from vegetations
Precipitation
(Rain, snow, etc. )
Evaporation
Water table
Percolation
Snow, etc.
Ocean
4.Evaporation – Transfer of water from liquid to vapour state is called
evaporation.
5.Transpiration – The process by which water is released to the atmosphere by
the plants is called transpiration.
6.Sublimation – Sublimation results from when pressure and humidity are low. It
is not only liquid water that can evaporate to become water vapor, but ice and
snow, too. Due to lower air pressure, less energy is required to sublimate the ice
into vapour.

42
Hydrologic cycle
Hydrologic cycle
Transpiration
from vegetations
Precipitation
(Rain, snow, etc. )
Evaporation
Water table
Percolation
Snow, etc.
Ocean
The hydrological cycle can be briefed by the following equation (hydrological
equation).
I – Q = ∆S
; where,
I = Inflow of water to a given area during any given time period,
Q = Outflow of water from the area during the selected time
period,
ΔS = Change in storage of water in the given area during the time
period.
This equation states that during a given period, the difference between the total inflow
of water and out flow of water must equal the change in storage of water

43
Factors affecting run-off
1. Nature of rainfall – Short and hard showers may produce relatively little run-off.
Rains lasting longer time results in larger run-off.
2. Topography of catchment area – Steep and impervious areas will produce large
percentage of run-off. The water will flow quickly and absorption losses will be
small. The size of catchment has a definite effect on the runoff. More the area,
more will be the runoff. So also, the shape will have a definite effect on the runoff.
In case of a fan-shaped catchment area, the period of the resulting hydrograph
will be less and thus more peak flow may be expected. In case of an elongated
catchment, the period of the resulting hydrograph (graph showing discharge
(runoff) of flowing water with respect to time for a specified time) will be
comparatively more and thus more will be the infiltration losses and less will be
the runoff.
Discharge Fan shaped catchment area Elongated catchment area
Time
Hydrograph of fan shaped
catchment area
Hydrograph of elongated
catchment area

44
Factors affecting run-off
3. Geology of area – The run-off is very much affected by the types of surfaces soil
and sub-oil, types of rocks, etc. Rocky areas will give more run-off while pervious
soil and sandy soil will give less run-off.
4. Vegetation –Thick vegetation like forest consumes a portion of rain fall and also
acts as a obstruction for run-off.
5. Other climate factors – Other factors such as temperature wind velocity,
humidity, annual rainfall etc., affect the water losses from watershed (small
streams) area.

45
Advantages of hydro electric power plants
1. Water source is perennially available. No fuel is required to be burnt to generate
electricity. It is aptly termed as 'the white coal'. Water passes through turbines to
produce work and downstream its utility remains undiminished for irrigation of
farms and quenching the thirst of people in the vicinity.
2. The running costs of hydropower installations are very low as compared to thermal
or nuclear power stations. In thermal stations, besides the cost of fuel, one has to
take into account the transportation cost of the fuel also.
3. The number of operations required is considerably small compared with thermal
power plants.
4. There is no problem with regards to the disposal of ash as in a thermal station.
5. The hydraulic turbine can be switched on and off in a very short time.
6. The hydraulic power plant is relatively simple in concept and self-contained in
operation.
7. Modern hydropower equipment has a greater life expectancy and can easily last 50
years or more. This can be compared with the effective life of about 30 years of a
steam or nuclear station.
8. Modern hydro-generators give high efficiency over a considerable range of load.
9. Hydro-plants provide additional benefits like irrigation, flood control, afforestation,
navigation and aqua-culture.
10.Being simple in design and operation, the hydro-plants do not require highly
skilled workers. Manpower requirement is also low.
11.The cost of land is not a major problem since the hydro-electric stations are
situated away from the developed areas.

46
Disadvantages of hydro electric power plants
1. Cost of transmission is high since most of the plants are in
remote areas.
2. Hydro-power projects are capital-intensive with a low rate of
return.
3. It takes considerable long time for the erection of such plants.
4. Power generation is dependent on the quantity of water
available, which may vary from season to season and year to
year. If the rainfall is in time and adequate, then only the
satisfactory operation of the plant can be expected
5. Such plants are often far away from the load centre and
require long transmission lines to deliver power. Thus the cost
of transmission lines and losses in them are more.
6. Large hydro-plants disturb the ecology of the area, by way of
deforestation, destroying vegetation and uprooting
people. The emphasis is now more on small, mini and micro
hydel stations.

Nuclear power plant
 In nuclear power plant, heat energy available from nuclear fission
is used for the generation of steam.
 Nuclear fission can be defined as the process, in which a nucleus
is split into two divisions, more or less of equal mass releasing
energy in the form of electromagnetic radiation and kinetic energy.
 Fission is caused by neutrons which being electrically neutrally
neutral can strike and fission the positively charged nucleus at
high, moderate, or low speeds.
 The heat produced by fission in the nuclear reactor is carried out
of the reactor by coolant. This heat is used to generate steam.
This heat transfer takes place in a heat exchanger such as
boiler.
 The pressurized steam is then fed to a steam turbine which is
connected to a generator.

Nuclear power plant
U-235
Incident neutron
Prompt neutron
Prompt gamma rays
Fission fragment
Fission fragment
Prompt neutron
Fission of Uranium-235

Components of Nuclear power plant
1. Nuclear reactor – It is an apparatus in which nuclear fuel is subjected to
nuclear fission.
2. Heat exchanger – The coolant gives up heat to the heat exchanger, which
utilized for generating steam. After giving up heat, the coolant is fed back to the
reactor.
3. Steam turbine – The steam produced in the heat exchanger is fed to turbine
for doing useful work.
4. Generator – The steam turbine drives the generator which converts
mechanical energy in to electric power.

Components of Nuclear reactor
Components of nuclear reactor
Reflector
Moderator
Fuel rods
Pressure vessel
Coolant
Coolant
Biological shield
Control rods

Components of Nuclear reactor
Nuclear reactor is an apparatus in which nuclear fuel is subjected to nuclear
fission.
1. Fuel – Nuclear fuels usually used in the reactors are isotopes (atoms of the
same element having the same numbers of protons, but different numbers of
neutrons) of Uranium and Plutonium. Isotopes like U-233, U-235 and Pu-239
can be fissioned by neutrons of all energies, whereas isotopes U-238. Th-232
(Thorium) and Pu-240 are fissionable by high energy (14 MeV) only. Usually
pellets of fissionable materials are arranged in tubes to form fuel rods.
2. Moderator – Moderator is used to slow down the kinetic energy of fast
moving neutrons. This has to be done as only the slow neutrons maintain the
fission chain reaction. The neutrons collide directly with the moderator and
thus slowed down. Substances like light water, heavy water, carbon,
beryllium are used as moderator.
3. Control rods – Control rods are used to control the nuclear chain reaction. It
is an essential part of a reactor and serves the following purposes .
a) For starting the reactor.
b) For maintaining at that level.
c) For shutting the reactor down under normal or emergency conditions.
Control rods are usually made up of cadmium and boron. Control rods
control the chain reaction by absorbing neutrons.

Nuclear power plant
4. Coolant – Purpose of coolant is to extract heat generated by the
fission process. The various fluids used as coolant are water (light
water /heavy water), gas (Air, CO2, Hydrogen), and liquid metal
cooled reactors etc.
5. Reactor vessel – It is a strong walled container housing the
reactor core, shield and the reflector. It is strongly built so as to
withstand high pressures developed.
6. Reflector – Reflector is used to reduce the loss of neutrons by
reflecting back into the core of the nuclear reactor. Reflector is
generally made of the same material as the moderator.
7. Shield – Shield prevents the transfer of radiation to the external
world.

Nuclear power plant
Advantages of nuclear power plant
1. No problem of fuel transportation, storage, etc.
2. Less man power is required.
3. It is more economical compared to thermal plant.
4. Power capacity of plant is very high.
5. Capital cost except for reactor is very less.
6. It does not depend up on the condition of the weather.
7. By this process we can conserve the fuels like oil, coal gases and other
by-products.
Disadvantages of nuclear power plant
1. Nuclear radiation causes severe environmental problems.
2. Disposal of radioactive nuclear waste is menace.
3. Varying load conditions are not suitable.
4. Capital cost is very high for the reactor.

Nuclear power plant
Types of reactors
Light water-cooled and moderated reactors (LWR) using
slightly enriched uranium fuel are the type most commonly used
for power production. These reactors are further divided into :-
1) Pressurized water reactor (PWR) and
2) Boiling water reactor (BWR).

Pressurized Water Reactor (PWR)
Condenser
Pressurized heated
water
Feed
water
Coolant pump Feed water pump
Feed water heater
Pressurizer
Steam
Turbine
Heat exchanger
(Boiler)
Reactor
Pressurized water reactor

57
Pressurized Water Reactor (PWR)

Pressurized Water Reactor
 Pressurized Water Reactor (PWR) make use of two loops viz., primary
and secondary loops to convert the heat generated by the fuel into
electric power.
 In the primary loop, the pressurizer maintains a high pressure in the
water in the range of 150 bar. The pressurized water (coolant) is
circulated in the reactor. Due to the high pressure of the water, the
water does not boil.
 The coolant gets heated in the reactor and the hot water enters the
boiler and transfers heat to the feed water in the boiler in the
secondary loop. The transfer of heat is accomplished without mixing
the two fluids, which is desirable since the primary coolant might
become radioactive.
 Feed water evaporates and runs the turbine.

Pressurized Water Reactor
Advantages of PWR
1. Because the water used in the high-pressure water loop is isolated from
water in the steam loop, no radioactive material is contained in the steam.
2. PWR has high power density and has compact size.
Disadvantages of PWR
1. Capital cost is high as high primary circuit requires strong pressure vessel.
2. In the secondary circuit, the thermodynamic efficiency of the plant is quite
low.

Boiling Water Reactor (BWR)
Condenser
Concrete shell
Feed pump
Thermal shielding
Uranium fuel
Moderator
Turbine
Generator
Coolant water
Boiling water reactor

61

 In Boiling Water Reactor (BWR), the coolant (water) used in the
reactor absorbs heat produced during the fission reaction in the
reactor.
 The fuel used is enriched uranium oxide. Water evaporates and
steam is generated in the reactor itself. In this type of reactor,
there is no need of separate boiler.
 In BWR, the coolant is in direct contact with turbines, so if a
fuel rod had a leak, radioactive material could be placed on the
turbine.

Advantages of BWR
 A major advantage of the BWR is that the overall thermal efficiency is
greater than that of a pressurized water reactor because there is no
separate heat exchanger.
 The pressure inside the pressure vessel is not high so, a thicker vessel is
not required.
Disadvantages of BWR
 Possibility of radioactive contamination in the turbine mechanism.

Gas turbine power plant
In steam turbine plants, the products of combustion do not form the
working medium. These are utilised to produce the intermediate fluid,
i.e., the steam which is expanded in the turbine. If this intermediate
step of converting water to steam by means of gases is eliminated, the
arrangement would be far simpler and less wasteful. This principle is
used in gas turbine power plants where the gases are directly
expanded through the several ring of fixed and moving blades.

Generator
Turbine
Compressor
Hot gas
Combustor
Nozzle
Fuel
Coupling
Air inlet Exhaust
Arrangement of simple gas turbine plant
 In principle, a gas turbine plant consists of a compressor in which the working
medium is raised to a high pressure. So, generally, a centrifugal or an axial
compressor is employed.
 The turbine drives the compressor and so it is coupled to the turbine shaft.
From the compressor, the working medium is taken to a combustor where its
temperature is raised. This high pressure and high temperature working
medium is then expanded in a gas turbine. In the turbine blading, the
expansion of the working gas takes place and the heat energy is converted first
into the kinetic energy and then into the work of the turbine shaft rotation.

Closed and open cycle plants
Work
Combustion
chamber
Shaft
Open cycle gas turbine
Fuel (heat)
Compressor
Air in Exhaust
Turbine
Closed cycle gas turbine
Work
Cooling chamber
Compressor
Heater
Shaft
Turbine
 In this turbine, the air from the
atmosphere is drawn into the
compressor.
 After compression, it is passed into a
combustion chamber.
 The hot gas is then made to flow over
the turbine blades. The gas, while
flowing over the blades, gets expanded
and finally exhausted into atmosphere.
losses in the drive.
 In this turbine, the working fluid
(eg. helium) is compressed.
 The compressed gas is heated (by
burning fuel or by nuclear reactor)
through a heat exchanger.
 It is then made to flow over the
turbine blades and gets expanded.
 From the turbine, the gas is passed
to the cooling chamber.
 The working fluid is then made to
flow into the compressor.

Components of a gas turbine power plant
1. Gas turbine – There are two basic types of gas turbines viz., radial
flow and axial flow turbines.
2. Air-compressor – There are mainly two types of air-compressors used
in gas turbine power plants viz., centrifugal compressor and axial
flow compressor.
3. Combustion chamber

68
Axial flow compressor of gas turbine power plant
Stationary blades
Casing
Rotor
Air out
Air in
Air out
Air in
An axial flow compressor

69
Air from air
compressor
Air stream around combustion chamber
Primary zone
Diluting or mixing zone
Igniter
Tertiary zone
Outer casing
Fuel oil from pump
A combustion chamber of gas turbine
Hot gases to
turbine nozzles
Combustion chamber of gas turbine power plant

Advantages of gas turbine power plant
1. The mechanical efficiency of a gas turbine (95%) is quite high as compared with
I.C. engine (85%) since the I.C. engine has many sliding parts.
2. The work developed by a gas turbine per kg of air is more as compared to an I.C.
engine.
3. Gas turbine power plants are compact in design and can generate high power.
They require less space than steam turbines or IC engines.
4. Compared with steam plants, they have lower initial cost per unit output.
5. Gas turbine power plants have bigger power weight ratio, so it is very useful for
marine power plants.
6. The machine is simple to operate and is smooth running.
7. It requires little or no water for cooling.
8. They have relatively low maintenance costs.
Disadvantages of gas turbine power plant
1. The thermal efficiency of a simple turbine cycle is low (15 to 20%) as compared
with I.C. engines (25 to 30%).
2. Its overall efficiency is very low since a large proportion of the power developed,
about three fourth, is required to drive the compressor and also by the
temperatures safely attainable.
3. The noise of operation is a source of extreme annoyance unless the plant design
includes sound control features.

Diesel engine
Fuel storage tank Pump
Air compressor
Service tank
Air filter
Diesel power plant
Generator
Compressed air
Fuel filter
Fuel injection pump
Hot oil
Cold oil
Lubricating
oil cooler
Silencer
Exhaust
Surge tank
Hot water
Pump
Cold water
To atmosphere
Heat
exchanger
Pump
Diesel power plant

Components of diesel power plant
1.Engine – For electric power generation, four-stroke engines are
predominately used. Horizontal engines are used for comparatively smaller
outputs, while vertical engines with multi-cylinder construction are used for
larger outputs. It is generally directly coupled to the generator.
2.Air supply system – Air from atmosphere after filtering is admitted to the
engine. In large plants supercharger (uses an air compressor that increases
the pressure of air supplied to the engine so that more fuel is burned and do
more work)/turbocharger (uses an air compressor driven by the exhaust
gases to compress the air supplied to the engine increasing the amount of
fuel and air fed into the engine and hence more efficient) is used to increase
the output power.
3.Exhaust system – Exhaust system is used to discharge the engine exhaust
to the atmosphere outside the building. A silencer is incorporated to reduce
the noise level.
4.Fuel system – Fuel is stored in the storage tank is pumped to a smaller
service tank at daily or short intervals. Fuel stored in the service tank is fed
to fuel filter and is finally injected in to the engine.

Components of diesel power plant
5.Cooling system – Hot water from the engine is carried to the surge tank.
From the surge tank, hot water is fed through the heat exchanger. In the
heat exchanger, cold water from the cooling towers is circulated which takes
away the heat of the water from the engine. Cold water is then pumped back
to the engine.
6.Lubricating system – It includes the oil pumps, oil tanks, filters, coolers
and pipe lines. Lubricating system provides lubricating oil to moving parts of
the system to reduce the friction and wear and tear of the engine parts.
7.Starting system – This is an arrangement to start the engine initially, until
firing starts and the unit runs with its own power. There are mainly three
types (1) petrol driven auxiliary engine (2) use of electric motors (3) use of
compressed air from an air compressor.
8.Governing system – The function is to maintain the speed of the engine
constant respective of load on the plant.

Diesel power plant
Advantages of diesel thermal power plant
1. Design layout of diesel power plant is simple and cheap.
2. Part load efficiency diesel power plant is very high.
3. Diesel power plant can be started quickly.
4. Maintenance of diesel power plant is easy.
5. Thermal efficiency of diesel is quite higher than of steam power plant.
6. It can also be designed for portable use.
7. Diesel plants can be located very near to the load centers.
Disadvantages of diesel thermal power plant
1. The cost of diesel is very high compared to coal. Hence, the running cost of
this plant is higher compared to steam and hydro power plants.
2. There is a limitation for size of a diesel engine.
3. Life is less.
4. Noise pollution is very high.
5. High maintenance and lubrication cost.
6. Capacity of diesel plants is limited.

Advanced energy engineering ktu module 1

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