diesel power station
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Electrical Power Generation – 2140908
Active Learning Assignment
“Topics”
Diesel Power Station
Guided By: Prof. Rahil sir
Branch : Electrical Engineering
Div: B
Batch : B1
Presented by:
Het amin-130120109002
Abdul chhipa-130120109005
Shah harshil-130120109012
CHEMICAL
ENERGYMECHENICAL
ENERGYELECTRICAL
ENERGY
FUEL
(DIESEL)
DIESEL
ENGINEALTERNATOR
R
YB
INTRODUCTION
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.
Fuel Supply SystemIn fuel supply system there are one storage tank, where oil in stored.
Strainer : This oil then pump to dry tank, by means of transfer pump.
During transferring from main tank to smaller dry tank, the oil passes through strainer to remove solid impurities. From dry tank to main tank, there is another pipe connection. This is over flow pipe. This pipe connection is used to return the oil from dry tank to main tank in the event of over flowing.
From dry tank the oil is injected in the diesel engine by means of fuel injection pump.
Air Intake SystemThis system supplies necessary air to the engine for fuel combustion. It consists of
a pipe for supplying of fresh air to the engine. Filters are provided to remove dust
particles from air.
Exhaust SystemThe 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.
Cooling SystemThe 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 requires a water source, 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.
Lubricating SystemThis 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.
Starting SystemFor 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.
APPLICATION OF DIESEL POWER
STATION They are used as central station for small or medium power supplies.
They can be used as stand-by plants to hydro-electric power plants and steam power
plants for emergency services.
They can be used as peak load plants in combinations with thermal or hydro-plants.
They are quite suitable for mobile power generation and are widely used in
transportation systems such as automobiles, railways, air planes and ships.
Now-a-days power cut has become a regular feature for industries. The only solution
to tide over this difficulty is to install diesel generating sets.
DISADVANTAGES
High running charges due
to costly price of Diesel
Generates small amount of
power
Cost of lubrication very
high
Maintenance charges are
generally high
ADVANTAGES AND DISADVANTAGES OF
DIESEL POWER PLANT
ADVANTAGE
Simple design & layout of plant
Occupies less space & is compact
Can be started quickly and picks
up load in a short time
Requires less water for cooling
Thermal efficiency better that of
Steam Power Plant of same size
Overall cost is cheaper than that of
Steam Power Plant of same size
CYLINDER It is the heart of the engine in which the fuel is burnt and the power is developed.
Cylinder has to withstand very high pressure and temperature because the combustion of fuel
is carried out within the cylinder so it must be cooled.
The inside diameter is called bore.
Cylinder head
Cylinder head covers top end of cylinder.
Valve mechanism, spark plug, fuel injector etc are placed on cylinder head.
Piston
The piston is a close fitting hollow cylindrical plunger reciprocating inside the cylinder.
The power developed by the combustion of fuel is transmitted by piston to the crank shaft through connecting rod.
Piston rings and pin
The piston rings are the metallic rings inserted into the circumferential grooves provided at the top end of the piston.
Piston ring is also known as gudgeon pin
It is pin joining small and of the connecting rod and piston and it is made of
steel.
Connecting rod It is the member connecting piston through piston pin and crank shaft
through crank pin.
It converts the reciprocating motion of the piston in to rotary motion of
crank shaft
Crank and crankshaft
The crank is a lever that is connected to the big end of the connecting rod
by a pin joint with its other end connected to shaft which called crankshaft.
Valves and fly wheels Engine has both intake and exhaust type of valves which are operated by valve
operating mechanism
Fly wheel is a heavy wheel mounted on the crankshaft of the engine and it minimize cyclic variation during the stroke
Crankcase and fuel pump and injector Crank case is the lower part of the engine serving as an enclosure of the
crankshaft
Fuel pump is used in diesel engine for increasing pressure and injector is used to inject diesel fuel in the form of spray under pressure.
Working of Two stroke
Diesel Engine
The construction of diesel engine is similar to two stroke petrol engine except the fuel pump and fuel injector are there instead of carburetor and sparkplug.
It consist two stroke in the cycle.
First stroke
At the beginning of the first stroke, the piston is at TDC and then moves to BDC. At TDC piston is at the end of compression, so the compressed air will attain a temperature higher than self ignition temperature of the diesel
The injector injects a metered quantity of the diesel into the cylinder as a fine spray. As diesel is injected it auto ignites.
The combustion of the diesel will release the hot gases which increases the pressure and temperate in the cylinder
Second stroke
In this stroke the piston moves from TDC to BDC. When it covers the
transfer port, the supply of air is stop and when it moves further up it
covers the exhaust port completely stops the scavenging
Further upward motion of the piston will compress the air in the cylinder
After the piston reaches TDC the first stroke repeats again
Suction strokeDuring this stroke, inlet valve opens and exhaust valve is closed, the pressure in the cylinder will be atmospheric. As the piston moves from TDC to BDC, the volume in the cylinder increases, while simultaneously the pressure decreases.
This creates a pressure difference between the atmosphere and inside of the cylinder.
Due to this pressure difference only the atmospheric air will enter into the cylinder through air filter and inlet.
At the end of this stroke, the cylinder will be filled completely with air and inlet valve will be closed
Working of Four stroke Diesel Engine
Compression stroke
During this stroke, both inlet valve andexhaust valve remain closed. The pistonmoves from BDC to TDC. As this strokeis being performed, the air in the cylinderwill be compressed, so pressure andtemperature of air increases.
The compression ratio of this engine ishigher than petrol engine. Due to highercompression ratio, air will have attained ahigher temperature than self ignitiontemperature of diesel fuel.
A metered quantity of the diesel fuel isinjected into the cylinder. As the dieselfuel particles come in contact with hightemperature it will ignite automatically.This is called self ignition
Power stroke
During this stroke, both the inlet valve and the exhaust valve are closed. The piston moves from TDC to BDC.
The fuel injection starts nearly at the end of compression stroke, but the rate of fuel injection is such that combustion maintains constant pressure.
This piston is forced further during the remaining part of this stroke only due to the expansion of the burnt gases. The engine produce mechanical work in this stroke
Exhaust stroke
During this stroke , the exhaust
valve opens and inlet valve is
closed. The piston moves TDC to
BDC.
During this motion, piston pushes
the exhaust gases out of cylinder at
constant pressure.
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