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DIESEL POWER PLANT
PRESENTATION BY

PARMAR PRIYANKA(11,01), DAVE NANDINI(08,07),
PATEL LEENA(10,03), PATEL AMISHA(09,404)
BARIA BHAVNA(11,04)
IT 5th SEM
PIET,WAGHODIA

The function of exhaust System :

1> To discharge 2>To reduce
engine exhaust pressure in
to the exhaust line
atmosphere And eliminate
outside the most of noise.
building and

The componets of exhaust System : :

cylinders muffler exhaust
manifold pipe

Engine exhaust, starting and stopping

Working

The exhaust manifold connects the engine
cylinders exhaust outlet to the exhaust pipe .
the exhaust gases from the cylinders collect
in the exhaust manifold & are conveyed to
the atmosphere through the exhaust pipe.

* The exhaust pipe is provided with a
muffler(silencer) to reduce pressure in exhaust line
& eliminate most of noise which may results if
gases are discharged directly into the atmosphere.
The exhaust manifold is connected with exhaust
pipe by one or two flexible expansion joints to allow
for the expansion & to minimize the effect of
engine vibration on system.

The temperature of exhaust gases leaving the engine is
about 400 C when it works under full load conditions.
Therefore large engine exhaust gases contains large amount
of heat. This heat can be recovered and utilized in three
manner as

1 To heat the water which is supplied to the cylinder jackets

2 To generate low pressure steam in the water heat boiler
which can be used for process heating

3 To heat ventilating air which is supplied to the engine

Designing an exhaust System

1. The exhaust noise should be reduced to the desired level.

2 The exhaust should be discharged sufficiently height above the
ground level in order to reduce the air pollution at ground level.

3 The expansion joints should be used to reduce the engine
vibration on the exhaust system

4 The pressure loss in the exhaust system should be minimum.

5 There should be provision to recover the heat of exhaust gases to
increase the efficiency of the plant.

Engine Starting by an
auxiliary small engine

There are two engines:

1 Diesel engine that is main
engine.

2 Small petrol engine.

Joining

Diesel engine and petrol engine are
joined by clutch and gear arrangements.

Small petrol engine can be easily started
by means of manual operations

Working process:
First clutch is disengaged and petrol engine is started by
hand operated system.

Then cluth gradually engaged and the power is transferred
to diesel engine .

Automatic disengagement of clutch takes place after main
engine has started.

The capacity of the starting petrol engine is just sufficient
to overcome the friction of the main diesel engine.

The compressed air system is generally used for starting
large diesel engine employed for power plant . In this
system compressed air a pressure of 17 bar is supplied
from an air bottle to the engine cylinder either through a
distributor or directly through inlet manifold .

In case of multicylinder engines, atleast one cylinder
remains on the suction stroke.

When compressed air under the pressure enters cylinder, it
pushes the cylinder thereby causing entire engine crankshaft
assembly to rotate.

Meanwhile the suction stroke of some other cylinder takes
place and the compressed air again pushes the piston of this
cylinder and causes the engine crank assembly to rotate.

Gradually the engine gains momentum and by turning on the
fuel supply , engine will start running.

Starting by electric
motor

The main advantages of electric starting are its
simplicity and effectiveness. This system is used
for small diesel engine.

This system consist of an electric motor which is
drives pinion which engages a gear toothed rim
on engine .

A storage battery of 12 to 36 volts is used to
supply power to an electric motor.

The first method from above as stopping fuel supply is the most
commonly used for stopping diesel engine ,in which the fuel supply
to injection pump is cut with the help of solenoid value as fig.

The solenoid valve is placed in the fuel supply line close to the inlet
of the injection pumps. The valve needle has a megnatic head which
is located inside a solenoid .When electric current is passed though
the coil,a magnetic force is set up which moves the valve needle and
allows fuel flow.

When hand operated switch button is the electric circuit is broken the
needed come back and closes the valve and hence engone is stopped.

The motor draws a heavy current and is designed to
engaged continuously for about 30 seconds only,
after which it is required to cool off for a minutes or
so, and then re-engaged. This is done till the engine
starts up.

There is also arrangement for automatic
disengagement after the engine has started.

When the engine is running a small d.c. generator
on the engine serves to charge the engine serves to
charge the battery otherwise small electric generator
driven from the engine may be used.

The engine should not be stopped abruptly
. in order to stop engine, the speed should
be decreased gradually until no power is
delivered by generator .Then the engine is
disconnected from the bus bars and is
allowed to run idle for sometime.

engine can be shut down with of
the any one of the following
methods.

2. keeping
1. Stopping
exhaust
fuel supply
value open

4. stopping
3. shutting
the action
of air
of injection
supply
pump.

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Engine exhaust, starting and stopping

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