Diesel Power Plant

Presented by:Andales, Madelyn M.Nolluda, Gerlie I. &Refrima, Christine Suzanne C.

3SE - BSEE

What is a Diesel Power Plant?

A Diesel power station (also known as Stand-by power station) uses a diesel engine as prime mover for the generation of electrical energy.This power station is generally compact and thus can be located where it is actually required. This kind of power station can be used to produce limited amounts of electrical energy. In most countries these power stations are used as emergency supply stations.

Diesel power plants are more efficient than any other heat engine of comparable size because:

i. These plants are cheap by way of initial cost

ii. It can be started and stopped quicklyiii. Can burn a wide range of fuelsiv. Does not require a warming periodv. Does not need a large amount of water

for cooling

Disadvantages of a Diesel Power Plant:i. High running charges due to costly price

of diesel.ii. Plant does not work efficiently under

prolonged overload conditions.iii. Generates small amount of power.iv. Lubrication cost is very high.v. Maintenance charges are generally high.

Important fields of Application of Diesel Power Plants Railroad locomotives Ship propulsion Road building and farm machinery Electric generators for small supply units

for public, industrial and institutional purposes

How does it operate?

The diesel burns inside the engine and the combustion process causes rotational mechanical energy that turns the engine shaft and drives the alternator. The alternator in turn, converts mechanical energy into electrical energy.

This type of electricity generating power station will probably be used a long time into the future, due to a need for reliable stand-by electrical source for emergency situations.

However, diesel power plants emit green house gases that pollute the environment and also require frequent servicing.

Working Principle of Diesel Power Plants & General Description An internal combustion engine in which

the fuel is ignited by injecting it into air that has been heated into a high temperature by rapid compression; hence, diesel engines are also called compression-ignition engines. The concept of Ignition Engines was patented by Rudolf Diesel in 1892.

What is a Compression-Ignition Engine? A compression-ignition engine (also known as a Diesel

engine) is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression. This is in contrast to spark-ignition engines such as a petrol engine (gasoline engine) or gas engine (using a gaseous fuel as opposed to gasoline), which uses a spark plug to ignite an air-fuel mixture. The diesel engine is modeled on the Diesel cycle. The engine and thermodynamic cycle were both developed by Rudolph Diesel in 1897.

Example of a Diesel Engine

Diesel Cycle

A repeated succession of operations representing the idealized behaviour of the working fluid in the diesel engine form of heat engine.

Main events that takes place in the Diesel Cycle:

a. Suction Operationb. Adiabatic Compressionc. Heat additiond. Adiabatic expansione. Heat removal (Rejection)

a. Suction Operation – at constant pressure in which air is sucked inside the cylinder from the atmosphere at nearly atmospheric pressure.

b. Adiabatic Compression of the working fluid along a b, the temperature and pressure are increased.

c. Heat addition along b c at constant pressure; the gas temperature and volume are increased.

d. Adiabatic expansion along c d, work is done by the expanding gas, and, the temperature and pressure decrease.

e. Heat removal (rejection) along d, a at constant volume; the pressure and temperature decrease, and the gas is restored to its initial condition at a. Here, the cycle is completed.

Diesel Fuels

A diesel engine can use a wide variety of fuels, ranging from natural gas to fairly heavy petroleum distillate oils which are cheaper than gasoline.

Diesel Electric Plant Main Components1. Engine2. Engine air intake system3. Engine fuel system4. Engine exhaust system5. Engine cooling system6. Engine lubrication system7. Engine Starting system

This is the main component of the plant which develops power. The engine may be horizontal or vertical type. Horizontal engines are used for comparatively smaller outputs while vertical engines with multi-cylinder construction are employed for larger outputs. The engines are available in low, medium and high speed ranges. Speeds commonly used are in the range from 500 to 1,000 rpm. The rating of an engine which should be specified correctly is the net output in kw developed continuously at the crankshaft coupling by the engine in good operating condition, at a height of less then 450 m, at a temperature of 32° C and a barometric pressure of 717.5 mm Hg. Diesel engines are available is sizes from 75 kw to 3,750 kw.

1. Diesel Engine.

2. Engine Air intake system

This includes air filters, ducts, and supercharger. This supplies the required air quantity of air for combustion.

3. Fuel System

This includes fuel storage tanks, fuel transfer pumps, strainers, heaters, and connecting pipe work.

4. Engine Exhaust System

To discharge the engine exhaust to the atmosphere outside the building.

5. Engine Cooling System

Includes coolant pumps, spray ponds, water treatment or filtration plant and connecting pipe work. The purpose of the cooling system is to carry heat from engine cylinder to keep the temperature of the cylinder within safe limits.

Different Methods of Engine Coolinga) Direct air coolingb) Indirect system

(Natural Circulation)c) Indirect Cooling with

forced circulation of water

d) Non-circulating cooling system with water.

6. Lubrication System

The life of the engine and the efficiency depend largely on the lubrication system.

Diesel Plant Efficiency and Heat Balance If heat produced by _X kg of oil = Y KCal (where

1kWh = 860 KCal) Then we can derive the overall power plant

efficiency as:

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THE END!

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