DIESEL ENGINE POWER PLANT

PREPARED BY

• SOHAIL ALI AZAD - 113250

• ABDUL MUQEET – 113231

• ISHTIAQUE AHMED - 113217

• A Generating station in which diesel engine is used as prime mover for generation of electrical energy is known as diesel power station .

• Diesel power plant produce power in the range of 2 – 50 MW .

• Diesel Power stations are favored where demand of power is less sufficient quantity of coal and water is not available

• They are used as standby set for continuity of supply such as hospitals, radio stations, cinema theatres, etc.

INTRODUCTION

ADVANTAGES• The design and layout of the plant are quiet simple.• It occupies less space.• It can be located at any place.• It can be started quickly and can pick up load in a short time.• It requires less quantity of water for cooling.• The overall cost is much less than that of steam power plant of same capacity.• The thermal efficiency of the plant is higher.• It requires less operating staff.

DISADVANTAGES

• The plant has higher running costs as the fuel that is used is costly.• The plant does not work satisfactory under overload conditions for a longer

period.• The plant can only generate small power.• The cost o lubrication is generally high.• The maintenance cost is also high.

APPLICATIONS

• They are used as central stations for small power supplies.• They can be used as standby plants to hydrodynami8c plants and steam

power plants In case of an emergency.• They can be used as peak load plants in combination with thermal or hydro

plants.• They are quiet suitable for mobile power generations and are widely used

in transportation systems such as automobile, railways, ships.

GENERAL LAYOUT

GENERAL LAYOUT

ESSENTIAL ELEMENTS OF DIESEL POWER PLANT

• Starting system • Air Intake System• Fuel supply system• Exhaust system • Cooling system • Lubrication system• Governing system

STARTING SYSTEM

• The function of this system is to start the engine from cold by supplying compressed air at about 17 bar from an air tank that is admitted into few cylinders making them work like reciprocating air motors to run the engine shaft

• Fuel is then injected into remaining cylinders and ignited in the normal way causing the engine to start

ENGINE SYSTEM• Generally classified as Two stroke engines and 4 stroke engines.• In diesel engine air is admitted into the cylinder and is compressed.• At the end of the compression stroke fuel is injected.• The burning gases expand and does work on the piston.• The gases are then exhausted from the cylinder.

AIR INTAKE SYSTEM• The air intake system conveys fresh air through pipes or ducts to (i) the air

intake manifold (ii) the supercharger inlet of a supercharged engine.• Air filter is used to remove the dust from air which is taken by the engine.• The super charger is used to increase the pressure of air supplied.• Air is firest drawn thru the filter to catch dirt particles that may cause

excessive wear in cylinders.• Filters may be of two types• Dry type (paper, cloth etc.)• Wet type (oil impingement type where oil helps to catch particles )

FUEL SUPPLY SYSTEM• It includes storage tank, fuel pump, fuel transfer pump, strainers and

heaters.• Pump draws diesel from storage tank through the filter to day tank.• The day tank is usually placed high so the diesel flows to engine under

gravity.• Diesel is filtered before being injected into the engine by the fuel injection

pump.

FUEL SUPPLY SYSTEM

This Sytem performs the following function • Filter the fuel.• Meter the correct quantity of the fuel to be injected.• Time the injection process.• Regulate the fuel supply.• Distribute the atomized fuel properly in the combustion chamber.

EXHAUST SYSTEM• This includes the silencers and connecting ducts.• The exhaust gases coming out of the engine is noisy.• Silencer is provided to reduce the noise.• Exhaust pipe leading out of the building in should be short in length with minimum number

of bends to provide as low a pressure loss as possible.• Each engine should have its independent exhaust system.• Where possible exhaust heat recovery should be made to improve plant thermal efficiency.

Eg. Air heating, steam generation in diesel steam power plant etc.

EXHAUST SYSTEM

COOLING SYSTEM• The cooling system consists of a water source, pump and cooling towers. The pump

circulates water through cylinder and head jacket. The water takes away heat form the engine and it becomes hot. The hot water is cooled by cooling towers and re circulated for cooling.

• The temperature of the burning fuel inside the engine cylinder is in the order of 2750deg Celsius. 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 circulating water.

• 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 system

COOLING SYSTEM

COOLING SYSTEMThere are two methods of cooling I.C. engines:1.Air cooling.2. Liquid cooling

COOLING SYSTEMAir cooling:• In this method, heat is carried away by

the air flowing over and around the cylinder.

• Fins are added on the cylinder which provide additional mass of material for conduction as well as additional area for convection and radiation modes of heat transfer

COOLING SYSTEMLiquid 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 convection and conduction.

• The liquid gets heated during its passage through the cooling jackets and is itself cooled by means of an air cooled radiator 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.

LUBRICATION SYSTEM

The following are the important functions of a lubrication system:

• LUBRICATION: To keep parts sliding freely past each other, reducing friction and wear.• COOLING: To keep surfaces cool by taking away part of the heat caused by friction.• CLEANING: To keep the bearings and piston rings clean.• SEALING: To form a good seal B/W the piston rings and cylinder walls.• REDUCING NOISE: to reduce the noise of the engine by absorbing vibration.

GOVERNING SYSTEM• The function of the governing

system is to maintain the speed of the engine

• This is done generally by varying fuel supply to the engine according to load.

• It is achieved with use of governors.

Supercharging:

The apparatus used to increase the air density is called supercharger. It is similar to a compressor(centrifugal type), which provides greater mass of charge with same piston displacement.

• The purpose of supercharging is to raise the volumetric efficiency above that value which can be obtained by normal 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 proportional to the air consumption.

Supercharging:

Three methods to increase the air consumption are 1. Increasing the piston displacement: leads to more size and weight, cooling problems 2. Running the engine at higher speeds leads to mechanical wear and tear. 3. Increasing the density of the charge, so that greater mass of charge is introduced in same volume.

The supercharger produces following effects: 1. Provides better mixing of air fuel mixture due to turbulent effect of supercharger. 2. The temperature of charge is raised as it is compressed, resulting in higher temperature within the cylinder, so better vaporization of fuel. 3. Power required to run the supercharger is obtained from engine

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