electrical engg. dept. - sanjay ghodawat polytechnic · sanjay ghodawat polytechnic, atigre...

Mr.Nitin S. Patil

Sanjay Ghodawat Polytechnic, Atigre

Electrical Engg. Dept.

Diesel Electric Power Plant

SGP-Atigre Electrical Engg Dept.

Mr.N.S.Patil 2

Chapter No. 4

Diesel Electric Power Plant

Total Marks: 12 Hours: 05

INDEX

Sr.No.

Contents Page No.

1 Introduction 3

2 Definition of Diesel Electric Power Plant 4

3 Basic Principal of Diesel Electric Power Plant 5

4 List of Diesel Electric Power Plant in India

5 Uses of Diesel Electric Station 6

6 Selection of Site for a Diesel Power Station 7

7 Schematic arrangement of Diesel-Electric Power Plant 8

8 Main Components of Diesel Electric Power Plant 9

9 Four Stroke Cycle Engine 20

10 Two Stroke Cycle Engine 22

11 Comparism between Four & Two Stroke Engines 26

12 Maintenance of Diesel Electric Power Plant 27

13 Advantages, Disadvantages & Application of Diesel Power Plant 28

14 Special Question asked for MSBTE Exam 30

15 Technical Words & its meaning 31


Mr.N.S.Patil 3

1. Introduction:

Q.1) How Electrical Power Produce using Diesel Power Plant?

In a diesel power station, diesel engine is used as the prime mover. The diesel

burns inside the engine and the products of this combustion act as the working fluid to

produce mechanical energy. The diesel engine drives alternator which converts

mechanical energy into electrical energy.

,

As the generation cost is considerable due to high price of diesel, therefore, such

power stations are only used to produce small power. Although steam power stations and

hydro-electric plants are invariably used to generate bulk power at cheaper costs, yet

diesel power stations are finding favour at places where demand of power is less,

sufficient quantity of coal and water is not available and the transportation facilities are

inadequate. This plants are also standby sets for continuity of supply to important points

such as hospitals, radio stations, cinema houses and telephone exchanges.

,

.


Mr.N.S.Patil 4

2. Definition of Diesel Electric Power Plant:

A generating station in which diesel engine is used as the prime mover for the

generation of electrical energy is known as diesel power station.

Or

For generating electrical power, it is essential to rotate the rotor of an alternator

by means of a prime mover. The prime mover can be driven by different methods. Using

diesel engine as prime mover is one of the popular methods of generating power. When

prime mover of the alternators is diesel engine, the power station is called diesel power

station.

The mechanical power required for driving alternator comes from combustion of

diesel. As the diesel costs high, this type of power station is not suitable for producing

power in large scale in our country.

But for small scale production of electric power, and where, there is no other

easily available alternatives of producing electric power, diesel power station are used.

http://www.electrical4u.com/alternator-or-synchronous-generator/

http://www.electrical4u.com/alternator-or-synchronous-generator/


Mr.N.S.Patil 5

3. Basic Principal of Diesel Electric Power Plant

Or

Chemical Energy of Diesel ↔ Heat Energy ↔ Mechanical Energy ↔Electrical Energy

4. List of Diesel Electric Power Plant in India?


Mr.N.S.Patil 6

5. Uses of Diesel Electric Station:

1. Central Station

2. Standby Plant ( )

3. Peak Load Plant ( )

4. Emergency Plant ( )

5. Mobile Plant ( )

6. Nursery Plant

7. Supply Units for Cinemas, Hospitals etc


Mr.N.S.Patil 7

6. Selection of Site for a Diesel Power Station:

1. Near to Load Center:

As far as possible the plant should be installed near to load center, to reduce

transmission & distribution cost of electrical energy.

(

)

2. Availability of Land:

For erection of diesel power plant, land should be available near to load center at low

cost.

3. Availability of Water:

The soft water is freely available for the purpose of cooling.

4. Foundations:

As we know that, the diesel engines or a machine produces vibrations. So provide

good foundation to erect the diesel engine.

5. Fuel Transportation:

The diesel plant is far away from fuel mines. So to provide fuel to the plant arrange

good transportation facility like road, rail etc.

6. Local Conditions:

For increasing the demand of power & future expansion space available.

7. Noise Pollution:

The plant should away from populated areas, because it produces noise.


Mr.N.S.Patil 8

7. Schematic arrangement of Diesel-Electric Power Plant:


Mr.N.S.Patil 9

8. Main Components of Diesel Electric Power Plant:

Q.1) List the main parts of diesel electric power plants.

The essential components of a diesel electric power plant are as follow:

1. Diesel Engine [ ]

2. Engine Fuel Supply System [ ]

3. Engine Air Intake System [ ]

4. Engine Exhaust System [ ]

5. Engine Cooling System [ ]

6. Engine Lubrication System. [ ]

7. Engine Starting System. [ ]

8. AC or DC Generators

The above figure shows the schematic arrangement of diesel power plant

(Page No. 4). We will study in brief the function of each component in the

plant.


Mr.N.S.Patil 10

1. Diesel Engine:

It is the main components used in diesel electric power plant for developing mechanical

power. This mechanical power we use to run the generator & produce electrical energy. For

producing the electrical energy the diesel engine is mechanically coupled to generator.

When the diesel fuel burning inside the engine, its start to produce a mechanical power.

The combustion of diesel fuel produces increased temperature & pressure inside the engine. Due

to this pressure gases are formed, this gas pushes the piston inside the diesel engine, and then

mechanical power is produced. With the use of this mechanical power the shaft of diesel engine

starts rotating.


Mr.N.S.Patil 11

2. Engine Fuel Supply System:

Q.1) Explain fuel system used in Diesel Electric Power Plant.

It consists of Fuel Storage Tank, Fuel Filter or Strainer, Fuel Transfer Pump, Day Tank,

Heaters & Connecting Pipes.

First up all with the help of transportation facility available (road, rail etc.) the diesel fuel

stored in storage tank. Then this diesel fuel transfer to day tank, the function of day tank is how

much quantity of diesel required for 24 hours is store. If the day tank is full or overflow occurs,

then excessive diesel returned to storage tank. The filter or strainer is used to purify diesel. With

the help of fuel transfer pump the diesel is transfer to day tank.

, , , ,

,

,


Mr.N.S.Patil 12

3. Engine Air-Intake System

Q.1) Explain Air-intake System of diesel power station in brief.

This System includes air filters, air tank, compressor & connecting pipes. The air

filters are used to supply the fresh air to diesel engine for the purpose of combustion.

Engine required fresh air because, if dust particles in the air entered into the engine will

cause disastrous effect to valve, cylinder & pistons. The compressor or Supercharger is

used to increase pressure of the air supplied to the engine. This will helps to increase the

output power.

, ,

-


Mr.N.S.Patil 13

4. Engine Exhaust System:

Q.1) Describe the following system of diesel power plants: Engine Starting System

& Engine Exhaust System.

Q.2) Describe the fuel & Exhaust System in Diesel Power Station

These systems consist of silencers & connecting ducts. As the temperature

of the exhaust gases is sufficiently high, it is used for heating the fuel oil or air

supplied to the diesel engine. The exhaust gas is removed from engine, to the

atmosphere by means of an exhaust system. A silencer is normally used in this

system to reduce noise level of the engine.

,


Mr.N.S.Patil 14

5. Engine Cooling System

The Diesel Engine Cooling System Consist of coolant pumps, water cooling towers or

spray pond, water treatment or filtration plant & Connecting Pipe Works.

The heat produced due to internal combustion, drives the engine. But some parts of this

heat raise the temperature of different parts of the engine. High temperature may cause

permanent damage to the machine. Hence, it is essential to maintain the overall temperature of

the engine to a tolerable level. Cooling system of diesel power station does exactly so.

The cooling system is required to carry heat from diesel engine to keep its temperature

within safe limits. The water pump circulates water to cylinder of diesel engine to carry away the

heat. The cooling tower is used for the same water reused.

The cooling system requires a water source, water pump and cooling towers. The pump

circulates water through cylinder and head jacket. The water takes away heat from the engine

and it becomes hot. The hot water is cooled by cooling towers and is re-circulated for cooling.

The cooling system can be classified into two types:

1. Open Cooling System: A Plant near the river may utilize the river water for cooling &

discharging again the hot water into river. This type of cooling system is known as open

cooling system.


Mr.N.S.Patil 15

, ,

2. Closed Cooling System: The Cooling Water is circulated again & again and only water

lost due to leakage, evaporation etc. is made up by taking make up water from supply

source.

,

, ,


Mr.N.S.Patil 16

6. Engine Lubrication System:

Engine lubrication system consists of lubricating oil pump, oil tanks,

filters, coolers, purifiers & connecting pipes. This system provides

lubricating oil to moving parts of the system to reduce the friction between

them wear & tear of the engine parts.

This system minimizes the water of rubbing surface of the engine. Here

lubricating oil is stored in main lubricating oil tank. This lubricating oil is

drawn from the tank by means of oil pump. Then the oil is passed through the

oil filter for removing impurities. From the filtering point, this clean

lubricating oil is delivered to the different points of the machine where

lubrication is required the oil cooler is provided in the system to keep the

temperature of the lubricating oil as low as possible.

It is then cooled through heat exchanger by means of cold water and then

it is fed to the engine.

, , , ,


Mr.N.S.Patil 17

7. Engine Starting System:

Q.1) Explain starting system used in Diesel electric power plant.

The function of starting system is to start the engine form stand still or cold

conditions by supplying compressed air.

For starting a diesel engine, initial rotation of the engine shaft is required. Until

the firing start and the unit runs with its own power. For small DG set, the initial

rotation of the shaft is provided by handles but for large diesel power station.

Compressed air is made for starting.

This system includes storage compressed air tank, self starter, auxiliary engines

& electrical motors (battery) etc.

1. Starting of Small Engine:

Small sets or small capacity of diesel engines are started manually.

2. Starting with the help of Auxiliary Engine:

When it is started by auxiliary engine, the auxiliary engine is

disengaged by the main engine & started by hand. When it is warmed up,

it is geared with the main engine so that it will start to rotate. After that

within, few seconds auxiliary engine disengaging.

3. Starting with the help of batteries:

To start the electrical motor batteries are used, the motor is geared

with diesel engine, it will start rotating with the motor & will start in few

seconds & as it picks up the speed the motor gets disengaged

automatically. In some cases the motor works as a generator, this will

further helps to charge the batteries.

4. Starting with the help of compressed air:


Mr.N.S.Patil 18

A large capacity (above 75kW) capacity diesel engines are started

with the help of compressed air. Diesel engines are started with the help

of compressed air following procedure adopted:

1. First up all open the compressed air valve, then starting lever

operated.

2. First up all air should be cut off in first combustion. Then open

ventilating valve. Start the engine after two or three revolutions.

, ,

1.

.

2.

3.

4. compressed air)

,

-


Mr.N.S.Patil 19

8. AC or DC Generators:

1. For Single Phase:

Single Phase, 230 Volts, and 50Hz frequency generators are used as per

requirements of load.

2. For Three Phase:

Generally, three phase, 50Hz, salient pole type, the number of poles

depends upon diesel engine speed. Generally, speeds of diesel engines are

low that’s why 6 or 8 poles generators used. Generators are coupled with the

shaft of diesel engine. These generators are 3.3kV, 6.6kV or 11kV output

capacities.

3. DC Generator:

Generally DC Compound generator is used, which help to develop an output

voltage of 230 Volts.


Mr.N.S.Patil 20

9. Four Stroke Cycle Engine:

Q.1) Describe the working of four-stroke diesel engine.

Q.2) state different types of engines in diesel power pl

---Or---

A four-stroke engine (also known as four-cycle) is an internal combustion

(IC) engine in which the piston completes four separate strokes while turning a

crankshaft. A stroke refers to the full travel of the piston along the cylinder, in

either direction. The four separate strokes are termed:

1. Suction: This stroke of the piston begins at top dead center (T.D.C.) and

ends at bottom dead center (B.D.C.). In this stroke the intake valve must be

in the open position while the piston pulls an air-fuel mixture into the

cylinder by producing vacuum pressure into the cylinder through its

downward motion.

Suction ,

https://en.wikipedia.org/wiki/Piston


Mr.N.S.Patil 21

2. Compression: This stroke begins at B.D.C, or just at the end of the suction

stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel

mixture in preparation for ignition during the power stroke (below). Both the

intake and exhaust valves are closed during this stage.

Compression ,

,

,

3. Power: This is the start of the second revolution of the four stroke cycle. At

this point the crankshaft has completed a full 180° revolution. While the

piston is at T.D.C. (the end of the compression stroke) the compressed air-

fuel mixture is ignited by a spark plug (in a gasoline engine) or by heat

generated by high compression (diesel engines), forcefully returning the

piston to B.D.C. This stroke produces mechanical work from the engine to

turn the crankshaft.

Power ,

4. Exhaust: During the exhaust stroke, the piston once again returns to T.D.C

from B.D.C while the exhaust valve is open. This action expels the spent air-

fuel mixture through the exhaust valve.

[ ,

]

https://en.wikipedia.org/wiki/Spark_plug


Mr.N.S.Patil 22

10. Two Stroke Cycle Diesel Engine:

Q.1) Explain the working of two stroke diesel engine with the help of neat diagram.

:

Compression:

Power:

Exhaust:

A two stroke diesel engine is a diesel engine that works in two strokes. A

diesel engine is an engine which operates using the Diesel cycle.

https://en.wikipedia.org/wiki/Diesel_engine

https://en.wikipedia.org/wiki/Two_stroke

https://en.wikipedia.org/wiki/Diesel_cycle


Mr.N.S.Patil 23

Q.1) Why the Two Strokes Engine more power produces than four-stroke engine?

A two-stroke diesel engine does not produce as much power as a four-

stroke diesel engine; however, it runs smoother than the four stroke diesel. This is

because it generates a power stroke each time the piston moves downward; that is,

once for each crankshaft revolution. The two-stroke diesel engine has a less

complicated valve train because it does not use intake valves. Instead, it requires a

supercharger to force air into the cylinder and force exhaust gases out, because the

piston cannot do this naturally as in four-stroke engines.

---OR---

Fig: Two Stroke Engine

One big difference between two-stroke and four-stroke engines is the

amount of power the engine can produce. The spark plug fires twice as often in a

two-stroke engine -- once per every revolution of the crankshaft, versus once for

every two revolutions in a four-stroke engine. This means that a two-stroke engine

has the potential to produce twice as much power as a four-stroke engine of the

same size.

http://auto.howstuffworks.com/engine.htm


Mr.N.S.Patil 24

It turns out that the diesel approach, which compresses only air and then

injects the fuel directly into the compressed air, is a much better match with the

two-stroke cycle.

Explanation of the above figure:

At the top of the cylinder are typically two or four exhaust valves that all

open at the same time. There is also the diesel fuel injector (shown above in

yellow). The piston is elongated, as in a gasoline two-stroke engine, so that it can

act as the intake valve. At the bottom of the piston's travel, the piston uncovers the

ports for air intake. The intake air is pressurized by a turbocharger or

a supercharger (light blue). The crankcase is sealed and contains oil as in a four-

stroke engine.

The two-stroke diesel cycle goes like this:

1. When the piston is at the top of its travel, the cylinder contains a charge of

highly compressed air. Diesel fuel is sprayed into the cylinder by the injector

and immediately ignites because of the heat and pressure inside the cylinder.

2. The pressure created by the combustion of the fuel drives the piston

downward. This is the power stroke.

http://auto.howstuffworks.com/turbo.htm

http://auto.howstuffworks.com/question122.htm


Mr.N.S.Patil 25

3. As the piston nears the bottom of its stroke, all of the exhaust valves open.

Exhaust gases rush out of the cylinder, relieving the pressure.

,

4. As the piston bottoms out, it uncovers the air intake ports. Pressurized air

fills the cylinder, forcing out the remainder of the exhaust gases.

5. The exhaust valves close and the piston starts traveling back upward, re-

covering the intake ports and compressing the fresh charge of air. This is

the compression stroke.

6. As the piston nears the top of the cylinder, the cycle repeats with step 1.

[

]

---


Mr.N.S.Patil 26

11. Comparism between Four & Two Stroke Engines

Sr.No. Particulars 4 Stroke 2 Stroke

1 Stroke Per Cycle 4 Piston Stroke 2 Piston Stroke

2 Crank Rotation per Cycle Two Crank Rotation Four Crank Rotation

3 Power Stroke per Cycle Half to Speed of

Crankshaft

Full to Speed of

Crankshaft

4 Power In Every Alternate

Revolution In Every Revolution

5 Flywheel Heavy Light

6 Size of Engine Heavier, Larger Lighter, More Compact

7 Space Required More Less

8 Valve Inlet & Exhaust In Place of Valve parts

are there

9 Crankcase It is not hermetically

Sealed Hermetically Sealed

10 Crankshaft Direction of

Rotation In One Direction In Both Direction

11 Lubricant Oil

Consumption Less More

12 Thermal Efficiency Higher Less

13 Mechanical Efficiency Low High

14 Uses Cars, Tractors, Buses Mopeds, Scooters,

Motor Cycles


Mr.N.S.Patil 27

12. Maintenance of Diesel Electric Power Plant

At the time of diesel engine or diesel electric power plant, following points

are considered during maintenance period.

a. To maintain the operating condition of diesel engine at every half

hour.

b. To maintain the correct record of the instrument reading in log sheet.

c. To maintain the record of instrument temperature, pressure, electrical

load, flow etc.

d. To check the level of fuel oil periodically.

e. Filterized the fuel and remove unwanted impurities.

f. Clean the fuel tank at regular interval.


Mr.N.S.Patil 28

13. Advantages, Disadvantages & Application of Diesel

Power Plant:

Q.1) State any FOUR advantages & disadvantages of diesel electric power plant

Advantages of Diesel Power Station

1. This is simple in design point of view.

2. Required very small space.

3. It can also be designed for portable use.

4. It has quick starting facility; the small diesel generator set can be started

within few seconds.

5. It can also be stopped as when required stopping small size diesel power

station, even easier than it’s starting

6. As these machines can easily be started and stopped as when required, there

may not be any standby loss in the system.

7. Cooling is easy and required smaller quantity of water in this type power

station.

8. Initial cost is less than other types of power station.

9. Thermal efficiency of diesel is quite higher than of coal.

10. Small involvement is less than steam power station.

11. It requires less operating staff.

12. The overall cost is much less than that of steam power station of same

capacity.

Disadvantages of Diesel Power Station

1. As we have already mentioned, the cost of diesel is very high compared to

coal. This is the main reason for which a diesel power plant is not getting

popularity over other means of generating power. In other words the running

cost of this plant is higher compared to steam and hydro power plants.


Mr.N.S.Patil 29

2. The plant generally used to produce small power requirement.

3. Cost of lubricants is high.

4. Maintenance is quite complex and costs high.

5. The plant doesn’t work satisfactorily under overload conditions for a longer

period.

6. The cost of lubrication is generally high.

7. The maintenances charges are generally high

Applications:

Q.1) Explain any SIX Applications of diesel power plants.

Q.2) Give FOUR Application of Diesel Power Plant

1. The diesel oil is used as a fuel in power generation.

2. It produces AC as well as DC Voltages.

3. It is used where small power is generation is requirement.

4. In case of any emergency diesel engines are used.

5. It is also used for peal load during small period of time.

6. It is used to restart the boilers.

7. It is used in remote places.

8. It can be used in areas having low load factor.


Mr.N.S.Patil 30

14. Special Question asked for MSBTE Exam:

Q.1) Explain how diesel power plants are used for starting power plant

Ans: At the time of starting new plant, when station auxiliaries etc. are not

fed from other sources, diesel plant is used to supply auxiliaries of the plant. When

auxiliaries are run, power can be started & generate electricity. The same action

will take place at the time of break-down of plant etc.

Q.2) State how diesel power plant can be used as peak load plant?

Ans: As diesel generating plant takes no time to start and stop. It can be

connected to the system at the time of peak load and normal load. It is not

economical to use them during normal loading as their generating cost is high.

Q.3) Write meaning of Captive Power Generation

Ans: Captive generating plant means a power plant set up by any person to

generate electricity primarily for his or her own use and includes a power plant set

up by any co-operative society or association of persons for generating electricity

primarily for use of members of such co-operative society or association.


Mr.N.S.Patil 31

15. Technical Words & Its Meaning

Sr.No. Words % its Meaning Sr.No. Words % its Meaning

1 Elements: 20 Duct:

2 Diesel power plant:

21

Purifier :

3 Engine: 22 Efficiency:

4 Engine fuel system:

23 Crank:

5 Engine Air Intake System:

24 Rotation:

6 Engine Exhaust System:

25 Compression: ,

7 Engine Cooling System:

26 Suction: ,

8 Engine Lubrication System:

27 Inject:

9 Maintenance: 28 Burn:

10 Generator: 29 Ignition:

11 Principle: 30 Mixture:

12 Peak Load:

31 Auxiliary:

13 Diesel Fuel: 32 Electric motor:

14 Mechanical Power: 33 Warm:

15 Components: 34 Ventilation:

16 Transfer: 35 Revolution:

17 Strainer: 36 Combustion:

18 Heater: 37 Noise:

19 Dust: 38 Overflow:

electrical engg. dept. - sanjay ghodawat polytechnic · sanjay ghodawat polytechnic, atigre...

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