Component s of Diesel Power Plants
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1. Engine
2. Air Intake System
3. Engine Starting system
4. Fuel System
5. Exhaust System
6. Cooling System
7. Lubricating System
Engine:
· It’s the main component of plants which develops power.
· Types : Two stroke, Four strokes.
· Air is passed into the cylinder, fuel is also injected.
· The fuel is burned and bring gases expand and do work on piston.
· Shaft of engine is coupled to generator. Burned gases are exhaust to atmosphere.
Air intake system:
· Removes dust from atmospheric air & supplies fresh air to engine.
· Types of filters :
1. Dry or oil bath filter.
2. Oil immersed type of filter.
Precaution’s for location:
1. Should not be located inside engine room.
2. Air intake line should not be too small or too long.
3. Air should not be taken from a confined space.
Engine Starting System:
Used to start the engine in cold conditions by supplying air.
Starting methods:
1. Auxiliary engine.
2. Self-starters
3. Compressed air system.
Auxiliary engine:
Auxiliary engine located close to main engine and driven through clutch and gears. Clutch is disengaged and engine is started.
Self-Starters:
Used in small diesel engines. Motor draws heavy current & designed to work continuously for 30sec after which it is cooled.
Compressed Air System:
Used in large diesel engines.
Compressed air supplied from air tank.
Fuel System:
Contains:
· Storage Tank
· Fuel pump
· Strainers
· Meters
· Day Tanks (Supplies daily fuel need of engines and contains min 8hours of oil requirement)
1.Fuel Injection system:
Functions:
1. Filters fuel.
2. Measures correct quantity of fuel to be injected.
3. Time the fuel injection.
Types:
1. Individual pump injection system.
2. Common rail injection system.
3. Distributor.
Individual Pump Injection System:
· Individual pump is connected to each fuel nozzle.
· Nozzles contain delivery value actuated by oil pressure.
· High cost of manufacture.
Common rail injection system:
· Single pump supplies fuel to header.
· Control valve is present to set the amount & time of injection of fuel.
Distributor System:
There os a pressure pump which meters the fuel & time of injection. Fuel enters the distributor blocks. From there fuel is distributed to cylinders in correct order.
2.Fuel Pump :
· Measures & delivers correct quantity of fuel at high pressure to injector.
· It consists of plunger. When it moves down , oil comes into the barrel through ports SP & Y when it moves up, fuel gets compressed and lifts delivery value & fuel flows to injected through passage (p).
3.Fuel Injection:
· Delivers fuel into combustion chamber where fuel is mixed with air.
· Fuel from pump enters through passage and lifts nozzle value. Fuel travels down nozzle & injected to cylinder. The injection pressure can be adjusted by adjusting the screw present above the spring.
Exhaust System:
Discharge engine exhaust to atmosphere. Includes silencers & connecting ducts.
Lubricating System:
It is used to reduce friction of moving parts & reduce wear & tear of the engine.
Contains:
· Oil pumps
· Oil tanks
· Filters
· Coolers & pipes.
Types:
1. Wet sump lubrication system
i)Splash System
ii)Semi pressure system
iii)Fuel pressure system
2. Dry sump lubrication system.
3. Mist sump lubrication system.
Splash System:
· Used in 4 stroke stationary engines.
· Bottom of sump contains lubricating oil. Scoop is located at the bottom which splashes oil from all the parts.
· Suitable for low & medium speed engines.
Semi pressure System:
· Combination of splash & pressure systems.
· Oil is pumped from the sump through a filter and fed to main bearings.
· Less cost.
Full pressure system:
· Oil is pumped from sump through filter under pressure to various parts for lubrication.
· Oil is supplied to big end & small end bearings.
Dry sump lubrication system:
· Used in two stroke cycle engines.
· Mixture of oil & fuel is induced through carburetor & is vaporized.
Cooling System:
Carries heat generated inside engine cylinder.
Methods:
1. Air cooling
2. Liquid cooling
i)Thermo-syphon cooling
ii)Forced or pump cooling
iii)Cooling with thermostatic regulator.
iv)Pressurized water cooling.
Air cooling:
· Engine is cooled by atmospheric air, which flows around engine.
· Used in scooters , motor cycles.
Advantage:
1. No danger of coolant leakage.
2. Simple design.
3. Less weight.
4. Easy installation.
Disadvantage:
1. Non uniform cooling.
2. Less output.
3. More maintenance.
4. Used in small engines only.
5. Noisy operation.
6. More maintenance.
Liquid Cooling:
Thermo Siphon Cooling:
· Hot water goes up and cold water comes down due to density without any pump.
· Top of radiator is connected to top of water jacket by a pipe & bottom of radiator to bottom of water jacket.
· Water travels down the radiator across which air is passed to coal it. Simple, Cheap , but slow cooling.
Forced cooling by pump:
· Pump forces water to circulate to engine.
· It may cause over cooling which causes corrosion.
Thermostatic Cooling:
· Thermostat maintains desired temperature to increase heat transfer in radiator.
Pressurized water cooling:
High water pressure is maintained to increase heat transfer in radiator.
Evaporative Cooling:
Water is allowed to evaporate by absorbing latent heat of evaporation from the cylinder walls.
The temperature of cooling water is allowed to reach 100c.
Governing System:
It is used to regulate the speed of the engine. This is done by varying the fuel supply according to the engine load.
