Hydro, gas, diesel power plant

POWER PLANT ENGINEERING
Unit No. 1 -Hydro
Gas, Diesel power
plants
Dnyan, Kala, Krida and Krishi Prathisthan’s
Department of Mechanical Engineering Prof. Kokare A.Y.

Unit No. 1 - Hydro Gas, Diesel
power plants
CO- Identify various
components of Hydro, Steam,
Gas, Diesel power plant.

 Energy- Its capacity to do work in various forms or
to produce the dynamic effect in a body.
 Sources of Energy and their Classification:
1. Conventional or non-renewable sources
a. Solid fuel- e.g. Wood, Coal, Cock etc.
b. Liquid fuels- petrol, diesel, kerosene etc.
c. Gaseous- natural, producer, blast furnace gas
d. Nuclear energy- U235 , Tr232
(1kg of 𝑈235 = 4.5x106 kg coal or 2x 106 kg of Oil.
2. Non-conventional or renewable sources
Hydro, Solar, Wind, Geothermal,
Tidal, Wave, Ocean thermal energy

 Indian Energy Scenario-
As per data of 31.03.2016
The per capita energy consumption is too low as compare
develop country. Its just 4% of USA and 20% of world
average.

Final Energy Consumption-

Hydro Power Plant:

Classification of Hydro-plant The hydro-power plants
can be classified as below:
According to the availability of head
1. High head plants
2. Low head plants
3. Medium head plants.
According to the nature of load
1. Base load plant 2. peak load plant
According to the quantity of water available
1. Run –of- river plant without pondage (which can store for
long period such as dry season or year)
2. Run –of- river plant with pondage
3. Hydroelectric plant with storage reservoirs
4. Pump storage plant
5. Mini and micro hydro plants

Storage Plants
These plants are usually base load plants. The hydro-
plants cannot be classified directly on the basis of head
alone
(a) High head plants. About 100 m and above.
(b) Medium head plants. about 30 to 50 m.
(c) Low head plants. Up to about 30 m.

Site Selection for the hydroelectric power plant:
1. Availability of water
2. Water storage capacity
3. Availability od water head
4. Accessibility of the site
5. Distance from the load center
6. Types of the land of site
Essential Element ofAWater-power Plant The essential
features of a water power plant are as below:
1. Catchment area.
2. Reservoir.
3. Dam and intake house.
4. Inlet water way.
5. Power house.
6. Tail race or outlet water way

Advantages of HEPP
1. Water source is available. No fuel is required to
generate electricity.
2. Very low running cost compare to thermal power
plant.
3. No problem of ash disposal as like thermal power
plant.
4. The hydraulic turbine can be switched on and off
during very short period of time.
5. Hydro plants provide benefits like irrigation flood
control.
6. Being simple in design and construction. Manpower
requirement is low.
7. Long life as compare to other power plant.

Disadvantages of HEPP
1. The installation period of hydro project is quite large.
2. Power generation is dependent on the quantity of water
available, which may vary from season to seasons and
year to year.
3. Such plant are often far away from load center and
required long transmission line to deliver the power. The
cost of transmission line and losses are more .
3. Large hydro plant disturb the ecology of the area by the
way of deforestation and uprooting of people.

MAINTENANCE PRACTICE
1.Water Intake, Water Conduit System andAssociated
Equipment
● Cavitation & erosion at top portion due to rushing of air
during fill up.
● The inspection schedule for the durability of anticorrosive
paints used.
● Replacement schedule for various vulnerable parts such
as bends, open conduits etc.
● Due to humidity open conduit deteriorates from outside.
As such inspection & cleaning to be carried out from time to
time at regular intervalsDepartment of Mechanical Engineering Prof. Kokare A.Y.

● Anticorrosive-painting schedules followed.
● Timely Operation & Maintenance of the cranes & hoists.
● Healthiness of control & protection for isolating
gates/valves & for cranes/hoists.
● Maintenance of trash-rack/intake gate filter.
● Maintenance of communication systems, availability of
power supply, equipment for emergency operations,
approach roads etc.

2. Turbine & itsAuxiliaries
Turbine
● Periodic NDT viz. Ultrasonic, etc.
● Polishing of the various under water parts of the turbines
once in a year to minimize the white pitting.
● Inspection & testing of the runners from experts to decide
residual life so as to initiate action for procurement of
runners for replacement.
● Inspection of labyrinth seals in case of reaction turbines.
● Painting of runner housing with anticorrosive I tar based
paints.

● Applying anti-erosion coating to the runner.
● Checking of brake jet operation in power stations having
Pelton turbines once in three months. Governor
● Purification of hydraulic oils by centrifugal as well as
electrostatic liquid cleaner.
● Periodic maintenance of the servo valves and motors
after carrying out inspection of the pistons & housings of
the servo valves and motors for their worn-out parts.
Replacement of the leaking seals.
● Survey of the component failure & procurement of the
same and maintain minimum inventory.

3. Generator & itsAuxiliaries
● Periodic checking of the foundations, tightening the bolts.
Filling the foundations with epoxy.
● Checking the vibrations periodically & history of the
recorded readings gives guidelines for realignment,
looseness if any, unbalanced electrical components,
increase in bearing gaps, coupling misalignment, uneven
stator -rotor air gap etc.
● Periodic cleaning or replacement of the generator air
coolers and bearing oil coolers to improve performance of
the generator.

● Primary and secondary testing of the protection system
for its healthiness and correct operation.
● Inspection of the CTs, PTs and bus bars for over heating,
temperature rise etc.
● Inspection of circuits for protection & control circuits &
mock trials of the fire fighting system along with evacuation
system. Checking weight loss of the CO2 cylinders and
replenish as per recommendations of OEM.

Diesel Power Plant:
Introduction
 Diesel power plants produce power in the range of 2 to 50
MW, are used as central stations for supply authorities and
work.
 They are used as standby sets for continuity of supply such as
hospitals, telephone exchanges, radio stations, cinema theatres
and industries.
 They are suitable for mobile power generation and widely used
in railways and ships.
 Used as Peak Load Plants, Mobile Plants, Stand By Units,
Emergency Plants, Starting Stations, Central Stations,
Industries where power requirement is small 500kW.

Advantages of Diesel power plant
:
 Design and installation are very simple.
 It can respond to varying loads without any difficulty.
 It occupies less space.
 For the same capacity diesel power plant is compact and
smaller than a thermal power plant.
 Require less quantity of water for cooling purposes.
 No problem of ash handling system.
Disadvantages of Diesel power plant:
 High operating cost.
 High maintenance and lubrication cost.
 The capacity of a diesel plant is limited. They cannot be constructed
in large sizes.
 In a diesel plant noise is a serious problem.
 Diesel power plants cannot supply over loads continuously where
as steam power plants can work under 25% overload continuously.

List of Diesel PowerPlants in INDIA

HeatEngine
Any type of engine or device that derives heat energy from
combustion of fuel and converts to mechanical energy.
 In an Internal combustion engine, combustion takes
place within working fluid of the engine, thus fluid gets
contaminated with combustion products.
 Petrol engine is an example of internal combustion
engine, where the working fluid is a mixture of air and
fuel .
 In an External combustion engine, working fluid gets
energy using boilers by burning fossil fuels or any other
fuel, thus the working fluid does not come in contact
with combustion products.
 Steam engine is an example of external combustion
engine, where the working fluid is steam.

ClassificationofIC
Engines1.According to cycle of operation
 Two Stroke Engine
 Four Stroke Engine
2.According to cycle of combustion
 Otto Cycle Engine(combustion at constant volume)
 Diesel Cycle Engine(combustion at constant pressure)
 Dual Combustion or semi – diesel cycle engine.
3.According to arrangement ofCylinder.
 Horizontal Engine Vertical Engine
 V-Type Engine Radial Engine
4. According to their Uses
 Stationary Engine
 Portable Engine
 Marine Engine
 Automobile Engine
 Aero Engine

5. According to fuel employed and
method of fuel supply to engine.
 Oil Engine
 Petrol Engine
 Gas Engine
6. According to method of ignition
 Spark ignition
 Compression ignition
7. According to speed of the engine
 Low speed Medium Speed HighSpeed
8.According to method of cooling
 Air Cooled Water Cooled
9. According to number of cylinders
 Single cylinder
 MultiCylinder

TermsRelating toIC
Engine

 Bore: The inside diameter of the cylinder.
 Stroke: The linear distance along the cylinder axis between
two limiting positions.
 Top dead centre(TDC): The top most position of thepiston
towards cover end side of the cylinder.
 Bottom dead centre(BDC): The lowest position of the piston
towards the crank end side of the cylinder.
 Clearance volume(Vc): The volume contained in the cylinder
above the top of the piston, when the piston is atTDC.
 Swept volume(Vs): The volume swept through by the piston in
moving between TDCand BDC.
Total volume =Swept volume +clearance volume
 Compression ratio (r): ratio of total cylinder volume to
clearance volume.
# 5:1 to 9:1 for Petrol engines
#14:1 to 22:1 for Dieselengines

FourStrokeDieselCycle
Engine

LayoutofaDieselpower
plant

1. Diesel engine :
• Diesel engine is a compression ignition(CI) engine.
• The two –stroke cycle engine is more favored for diesel power
plants.
• The air required for the diesel engine is drawn through the air filter
from the atmosphere and compressed inside the cylinder.
• The fuel(diesel) from the diesel engine is drawn through a filter
from the all day tank and injected into the cylinder through fuel
injectors.
• Because of the high temperature and pressure of the compressed air,
the fuel ignites.
• The fuel burns and the burnt gases expand to do work on the moving part
inside the cylinder calledpiston.
• This movement of the piston rotates a flywheel and the engine is directly
coupled to electric generator.
• The gases after expansion inside the cylinder is exhausted into the
atmosphere and passes through a silencer in order to reduce the noise.

2.Starting system
• Diesel engine used in diesel power plants is not self starting. The engine
is started from cold condition with the help of an air compressor.
3. Fuelsupply system
• Fuel from the storage tank is pumped through a filter into a smaller
tank called all day tank. This tank supplies the daily requirements of the
diesel engine.
• The all day tank is placed high so that the fuel flows to the engine under
gravity with sufficient pressure.
4. Airintake system
• The air required for the combustion of fuel inside the diesel engine
cylinder is drawn through the air filter. The purpose of the filter is to
remove dust from the incoming air.
• The dry filter may be made of felt, wood or cloth.
• In wet filter, oil bath is used. In this the air passes over a bath of oil
where the dust particles get coated on the oil.

5. Exhaust system:
• The exhaust gases coming out of the engine is very noisy. In
order to reduce the noise a silencer(muffler) is used.
6. Lubricating System:
• This circuit includes lubricating oil tank, oil pump and oil
cooler.
• The purpose of the lubrication system is to reduce the wear of
the engine moving parts. Part of the cylinder such as piston,
shafts, valves must be lubricated.
• Lubrication also helps to cool the engine.
• In the lubrication system the oil is pumped from the
lubricating oil tank through the oil cooler where the oil is
cooled by the cold water entering the engine.
• The hot oil after cooling the moving parts return to the
lubricating oil tank

7. Coolingsystem
• The temperature of the burning fuel inside the engine
cylinder is in the order of 1500 to 2000 degree Centigrade.
In order to lower this temperature water is circulated
around the engine.
• The water envelopes(water jacket) the engine. The heat
from the cylinder, piston, combustion chamber etc., is
carried by the circulatingwater.
• The hot water leaving the jacket is passed through the heat
exchanger.
• The heat from the heat exchanger is carried away by the
raw water circulated through the heat exchanger and is
cooled in the cooling tower.

FOR GOOD PERFORMANCE OF DIESEL POWER PLANT
 Necessary to maintain the cooling temp within prescribed
limits.
 Lubricating system should work effectively and required
temp and pressure should be maintained.
 The engine should be periodically run even when not
required, should not stand idle for more than 7 days.
 Air filters, oil filters and fuel filters should be periodically
serviced.
 Periodic checking of engine compression and firing
pressure and exhaust temp.

Air intake system
 The air intake system conveys fresh air through pipes or ducts
to the 4-stroke engine, scavenging pump & to the supercharger.
 A large diesel engine requires 0.076 to 0.114 m3 of air
/min/KW of power developed. Air is first drawn through a filter
to catch dirt or particles that may cause excessive wear in
cylinders. Filters may be of following types:
a. Dry type (paper, cloth, felt, glass wool etc)
b. Wet type (oil impingement type, oil bath type where oil helps
to catch particles)
Air intake system

Lubrication system
It includes the oil pumps, oil tanks, filters, coolers and
connecting pipes.
The purpose of the lubrication system is to reduce the
wear of the engine moving parts
Part of the cylinder such as piston , shafts , valves
must be lubricated. The lubricant is cooled before
recirculation.
Lubrication also helps to cool the engine.

Fuelsystem
It includes the storage tank, fuel pump, fuel transfer pump, strainers
and heater.
Pump draws diesel from storage tank to day tank through thefilter
The day tank is usually placed high so that diesel flows toengine
under gravity.
Diesel is filtered before being injected into the engine by the fuel
injection pump.
strainers

Thefuel injection systemperforms the
followingfunctions
Filter the fuel
Meter the correct quantity of the fuel tobe injected
Time the injection process
Regulate the fuel supply
Secure fine atomization of fuel oil
Distribute the atomized fuel properly in the combustion
chamber
 Oil is atomized either by blast or pressurejet.
In pressurejet atomization oil is forced to flow
through spray nozzles at pressure above 100bar.It is
known as solid injection

Classification of solid injection systems
Common rail injection system: The system is named
after the shared high-pressure
bars)reservoir (common rail) that
(100
supplies
to200
the
cylinders with fuel. With conventional diesel injection
systems, the fuel pressure has to be generated
individually for each injection. With the common rail
system, however, pressure generation and injection are
separate, meaning that the fuel is constantly available
at the required pressure forinjection.
Individual pump injection system
Distributor system

Common rail injection system
The system is named after the
shared high-pressure (100 to
200 bars)reservoir (common
rail) that supplies all the
cylinders with fuel. With
conventional diesel injection
systems, the fuel pressure has
to be generated individually
for each injection. With the
common rail system, however,
pressure generation and
injection are separate,
meaning that the fuel is
constantly available at the
pressure forrequired
injection.

Individual pump Injection
System
The schematic is
shown in fig.
An individual pump or
pump cylinder
connects directly to
each fuel nozzle.
Metering and injection
timing controlled by
individual pumps.
Nozzle contains a
delivery valveactuated
by the fuel pressure.

Distributor System
The schematic is
shown here.
The fuel is metered
at a central point.
A pump
pressurizes
meters,
and
fueltimes the
injection.
Fuel is distributed to
cylinders in correct
firing order by cam
operated
valves which
poppet
admit
fuel to nozzles.

Cooling system
The temperature of the hot gases inside the cylinder may
be as high as 2750 c . If there is no external cooling, the
cylinder walls and piston will tend to assume the average
temp. of the gases.
Cooling is necessary because:
 Toavoid deterioration or burning of lubricating oil.
 The strength of the materials used for various engine parts
decreases with increase in temperature. Local thermal
stress can develop due to uneven expansion of various
parts.
 Increase in pre-ignition and knocking
 Due to high cylinder head temp. the volumetric efficiency
and hence power output of the engine arereduced.

Elements of cooling system

Liquid cooling
 In this method, the
cylinder walls and head
are provided with
jackets through which
the cooling liquid can
circulate.
 The heat is transferred
from the cylinder walls
to the liquid by
andconvection
conduction.
 The liquid gets heated
during its passage
through the cooling
jackets and is itself
cooled by means of an
air cooled radiator
system.

Phases in CIengine
combustion
In the C.I. engine, combustion may be considered in
four distinctstages,
a. Ignition delay period
b. Period of rapid or uncontrolled combustion
c. Period of controlled combustion
d. After burning

Combustion phenomenon in CI engine

Ignition Delay
The ignition delay in a diesel engine is defined as the
time interval between the start of injection and the
start of combustion. This delay period consistsof
(a)physical delay, wherein atomization, vaporization
and mixing of air fuel occur and
(b)of chemical delay attributed to pre-combustion
reactions.
Physical and chemical delays occursimultaneously.

Due to the delay period the pressure reached during
second stage will depend up on the duration of delay
period.
The longer delay will cause rough running and may
cause diesel knock.
Delay period should be as short as possible both for
the sake of smooth running and in order to maintain
control over the pressurechanges.
But , some delay period should be necessary other wise
the droplets would not disappear in the air for
complete combustion.

It is the second stage of combustion in C.Iengine.
This period is counted from end of the delay period to
the point of maximum pressure on the indicator
diagram.
The rise of pressure is rapid because during the delay
period the droplets of fuel have had time to spread
themselves over a wide area and they have fresh air all
around them.
About 1/3of heat is evolved during thisperiod
Period Of Rapid Or Uncontrolled
Combustion

At the end of the second stage of combustion , the
temperature and pressure are so high that the fuel
droplets injected in third stage burn almost as they
enter and any further pressure rise can becontrolled
by injection rate .
The heat evolved at the end of the compression is
about 70to 80 percent.
PERIODOFCONTROLLED
COMBUSTION

After burning
The combustion continues even after the fuel injection
is over , because of poor distribution ofparticles
This burning may be continue in the expansion stroke
up to 70to 80(deg) of crank revolution from TDC.
The total heat evolved by the entire combustion
process is 95 to 97%; 3to 5% of heat goes as un burnt
fuel in exhaust.

Delay Period in CI
engines
It is the time immediately following injection of the fuel during
which the ignition process is being initiated and pressure does
not rise beyond the value it would have due o the compression of
the air.
The delay period extend for about 13degC, movement of the
crank.
Delay period depends upon following:
 Temperature and pressure in the cylinder at time ofinjection.
 Nature of the fuel mixture strength.
 Presence of residual gases.
 Rate of fuel injection.
 It should be as short aspossible

 Diesel Knock
 If the delay period of C.I. engine is long a large amount
of fuel will be injected and accumulated in he chamber.
The auto ignition of this large amount of fuel may cause
high rate of pressure rise and high maximum pressure
which may cause knocking in the diesel engine.
 Effects of Supercharging
The Power output of a supercharged engine is higher than
its naturally aspirated counterpart.
The mechanical efficiencies are better than naturally
aspirated engines.
It has higher specific fuel consumption that naturally
aspirated engines.

Supercharging
 The purpose of supercharging is to raise the volumetric
efficiency above that value which can be obtained bynormal
aspiration.
 The engine is an air pump, increasing the air consumption
permits greater quantity of fuel to be added, and results in
greater potential output.
 The power output is almost directly prop. Totheair
consumption.
 3methods to increase the air consumption of an engineare:
1.Increasing the piston displacement: leads to more size and
weight, cooling problems
2.Running the engine at higher speeds leads tomechanical
wear and tear.
3.Increasing the density of the charge, so that greatermass
of charge is introduced in same volume.

Hydro, gas, diesel power plant

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