What is Diesel Power Plant?
The diesel power uses a diesel engine to rotate alternators and produce electrical energy. The diesel engine is used as a prime mover and this power plant is known as a diesel power plant.
Due to the combustion of diesel, rotational energy is generated. The alternator is connected with the same shaft of the diesel engine. And the alternator is used to convert the rotational energy of the diesel engine into electrical energy.
In most cases, the diesel power plant is used to generate electrical energy for small-scale production and at the load end. When the grid power is not available, the diesel engine is used to supply load in emergency conditions.
Generally, the capacity of diesel power plants is between 2 to 50 MW is used in central power plants to meet peak demand in steam power plants and hydroelectric power plants. But nowadays, due to the high cost of fuel, diesel engines are not used for such applications.
Different components or system used in a diesel power plant is as listed below.
- Diesel engine
- Air intake system
- Exhaust system
- Cooling water system
- Fuel supply system
- Lubrication system
- Diesel engine starting system
Diesel Engine
A diesel engine is the main component of a diesel power plant. It is used to generate mechanical power in form of rotation energy with the help of the combustion of diesel. An alternator is connected to the same shaft as the diesel engine.
There are two types of diesel engines;
- Two-stroke engines
- 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.
Compared to four-stroke engines, two-stroke engines have a low weight-to-power ratio, are more compact, easy to start, and have low capital cost. But the thermodynamic efficiency of a two-stroke engine is less compared to four-stroke engines. Two-stroke engines require more cooling water and consume more lubricants.
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. The required capacity of a diesel power plant can be calculated by the below equation.
Capacity of Plant = (Connected Load × Demand Factor) / (Diversity Factor)
The diesel engine power plant below 3 MW capacity is used as standby plants and 3 to 25 MW plants are used as baseload plants. Generally, in this type of plant, four-stroke engines are used. The plants used for baseload plants have a capacity of above 10 MW capacity and for these plants, two strokes engines are used.
Two-stroke Engine:
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of the crankshaft. A four-stroke engine requires four strokes of the piston to complete a power cycle during two crankshaft revolutions. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust (or scavenging) functions occurring at the same time.
Two-stroke engines often have a high power-to-weight ratio, power being available in a narrow range of rotational speeds called the power band. Two-stroke engines have fewer moving parts than four-stroke engines.
Advantages (or Pros) of Diesel Power Plant
- The construction of diesel power plant is simple.
- The diesel power plant can be easily installed at any place where the demand for power is very less.
- Time required to start and stop this power plant is very minimum as compare to time take by other plants to start and stop.
- It starts quickly and easily picks up the load variations.
- The maintenance cost is minimal as compared to the thermal and steam power plants.
- It requires minimum quantity of water which is essential for cooling purpose.
- For the installation of the power plant, sufficient area that is required is very less.
- This plant does not require more labours or workers under operation conditions.
- The diesel power plant has more thermal efficiency as compared to the steam power plant.
- It is widely used as a standby set in compact areas (like as hospitals, cinema houses, industrial machineries, etc.) that can provide a continuous power supply to the load.
Disadvantages (or Cons) of Diesel Power Plant
- The running cost of diesel power plant is high because diesel fuel is more expensive.
- It is not much comfortable under the overload condition and long duartion.
- This plant has limited power generation and storages capacity than thermal and hydroelectric power plants.
- The maintanance charge and lubrication cost are very high.
- This diesel power plant produces limited amount of electricity (approximately 50MW).
- The life span of the diesel energy is relatively short.
Hopefully, I have covered all the basic pros and cons of diesel power plants over the thermal power plant and the hydroelectric power plant. If you have any queries or doubts, comment below.
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