Diesel Power Plant
Diesel Power plant is the power generating plant which uses diesel engine as prime mover. In this power plant diesel engine is coupled with alternator. The diesel engine rotates the alternator and produces electric power.
Although steam power stations and hydroelectric power plants are widely used to generate bulk power at cheaper cost, yet diesel power stations are finding, favour at places where demand of the power is less, sufficient quantity of coal and water is not available and the transportation facilities are inadequate. These plants are mainly used as standby sets for continuity of supply to important points such as hospitals, radio stations, cinema, telephone exchanges, universities etc.\\The required capacity of a diesel power plant can be calculated by the below equation.\\Capacity of Plant = (Connected Load × Demand Factor) / (Diversity Factor)
Schematic Diagram of Diesel Power Plant
Components of Diesel Power Plant
The essential components of a diesel electric power plant are as follow:
- Diesel Engine
- Engine Fuel Supply System
- Engine Air Intake System
- Engine Exhaust System
- Engine Cooling System
- Engine Lubrication System.
- Engine Starting System.
- Governing system
- AC or DC Generators
\;\;\;Diesel Engine: It is the main component of the plant which develops the required power. It is used to generate mechanical power in form of rotation energy with the help of the combustion of diesel. The shaft of the engine is directly coupled with the shaft of generator / alternator, causing the rotation in alternator which in turn produce electric power.
There are two types of diesel engines – Two-stroke engines and Four-stroke engines. In two-stroke engines, every revolution of the crankshaft, one power stroke is developed. And in four-stroke engines, one power stroke is developed every two revolutions of the crankshaft. Four-stroke engines are more preferred over two-stroke engines for the application of small-scale generation and DG sets. And for large-scale production, two-stroke engines are preferred.
\;\;\;Engine Fuel Supply System: It consists of a storage tank, where we store oil supplied to the plant. All day fuel tank, it stores quantity of diesel required for 24 hours. Strainer which used to remove suspended impurities of the oil, and fuel injection(transfer) pump which used to inject the clean oil into the engine.
\;\;\;Air Intake System: This system supplies fresh air to the engine for the combustion of fuel. it may be dry(or oil) bath filter or oil immersed filter, and it consists of pipes to supply the fresh air and filters to remove dust particles from the air.
\;\;\;Engine Exhaust System: This system removes the gases produced due to combustion of fuel into the atmosphere. To reduce the noise level, the exhaust system must be provided with mufflers and silencers.
\;\;\;Engine Cooling System: During the combustion of fuel, heat is produce which increases the temperature of the engine. To maintain the temperature of the engine within the limits, the cooling system is provided. It consists of water source, a water pump which circulates water through a cylinder, and cooling waters which used to cool the hot water.
\;\;\;Engine Lubrication System: As the engine runs there is a friction between various parts of the engine. In order to minimize the wear and tear of the rubbing surface of the engine lubrication system is necessary. The components of the engine which must be lubricated are Piston and cylinder, Main crankshaft bearings, Cam, camshaft, and its bearings and Ends of bearings at connecting rod. The lubrication system consists of lubricating tank, pump, filter and oil cooler.
\;\;\;Engine Starting System: At the time of starting, the temperature and pressure of the cylinder are not sufficient to initiate the combustion. Hence, starting of the engine is not conductive for initiation of combustion. Engine start system rotates the engine initially till the unit runs on its own power. Small sets are started manually by handles but for large units, compressed air is used for starting.
\;\;\;Governing system: it’s used to control the speed of the engine by changing the fuel provide according to engine load.\\\;\\\;\;\;AC Generators: AC generators or alternators convert the mechanical energy of engine into electrical energy. The rotor of the alternator (or AC Generator) is coupled with the shaft of the engine. The engine rotates the rotor of the alternator which then produce electrical energy.
Advantages of Diesel Power Plant
The Various advantages of diesel power plants are mentioned below.
- It can start and stop quickly when required and it can pick up the load in a short time.
- A diesel power plant requires less space because the number and size of its auxiliary equipment is small, Thus it can be located at any place and it is easy to install for a small capacity power plant.
- It can easily be started and stopped as when required, there may not be any standby loss in the system.
- For the same capacity, The thermal efficiency of this plant is higher than a steam power plant.
- A diesel power plant requires Less staff for the operation.
- Initial cost is less than other types of power station.
Disadvantages of Diesel power Plant
The various disadvantages of diesel power plant are
- They can be used only in small sizes
- They have high operating cost because of high cost of diesel.
- Their life is very short, only about 5 years.
- Their overload capacity is small.
- They are polluting the air.