In this post, you will learn about the diesel power plant with its diagram, layout, components, working, advantages, and applications.
Download the PDF file of this article at the end of it. So let’s start with an introduction of diesel power plant.
What is Diesel Power Plant?
The diesel power plants are installed where the supply of coal and water is not available in sufficient quantity or where power is to be generated in small quantities or where standby sets are required for continuity of supply such as in hospitals, telephone exchanges, etc.
Diesel combustion results in the production of rotational energy. The diesel engine’s shaft is connected to the alternator. Additionally, the alternator is used to transform the diesel engine’s rotational energy into electrical energy.
The diesel power plant is typically used to produce electrical energy at the load end and for small-scale manufacturing. In emergency situations, the diesel engine is used to supply load when grid power is unavailable.
Diesel power plants typically have a capacity of 2 to 50 MW and are used in central power plants to handle peak demand in steam power plants and hydroelectric power plants. But today, diesel engines are not used for such applications because of the high cost of fuel.
Diesel power plants are generally used as follows:
- Peak load plant: The diesel power plant is mainly used along with thermal/hydroelectric plants as a peak load plant.
- It is used as a mobile plant.
- These can be used as a standby unit to supply part load.
- These can be used as an emergency plant for communication and water supply under emergency conditions.
- The diesel power plant is used as a Nursery station to supply power to a small town or city.
- Used as a starting station for starting large steam plants.
- Used as a central station.
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Diesel Power Plant Diagram
A simple diesel power plant is shown in the figure. Diesel engines are generally classified into four strokes and two-stroke engines. Generally, two-stroke engines are used for diesel power plants.
The compressor draws the air from the atmosphere and compresses it. The compressed air is supplied to the engine through the filter for starting, where it is compressed by a piston in a cylinder.
The fuel oil is supplied from the tank through the filter to the fuel injectors. The fuel injector injects the fuel into the cylinder and mixes it with compressed air.
The cooling water is continuously supplied to cool the engine and lubricating oil is supplied to lubricate the engine parts. The air intake supplies the air to the engine for subsequent operations.
Layout of Diesel Power Plant
The layout of a diesel power plant is shown in the figure. Air from the atmosphere is drawn into the compressor and it is compressed. The compressed air is sent to the diesel engine through the air filter. In the air filter, dust, and dirt from the air is filtered and only clean air is sent to the diesel engine.
Fuel oil from the tank is passed through the filter, where the oil gets filtered and the clean oil is injected into the diesel engine through the fuel pump and fuel injector. The mixture of the compressed air and spray of fuel oil is ignited in the engine and the combustion takes place. The released heat energy is utilized for driving the generator, which produces power.
- Fuel supply system
- Air intake and exhaust system
- Lubricating system
- Starting system
- Cooling system
1. Fuel supply system
This system consists of a fuel tank for the storage of fuel, fuel filters, and pumps to transfer and inject the fuel. The fuel oil may be supplied at the plant site by trucks, road, rail, tank, etc.
2. Air Intake and exhaust system
This consists of a compressor, a filter for the supply of air, and pipes for exhaust gases. Filters are provided to remove dust, dirt, etc., from the incoming air. In the exhaust system, a silencer is offered to reduce the noise.
The followings are the functions of the air intake system:
- To clean the intake air supply.
- Is to silence the intake air.
- To supply the air for supercharging.
3. Lubricating system
4. Starting system
For starting the engine initially, the various things used are compressed air, a battery, a self-starter, or an electric motor.
5. Cooling system
This system provides proper control of water circulation all around the diesel engines to keep the engine temperature reasonably at a low level. The hot water from the jacket is cooled in cooling ponds and is re-circulated again.
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Components of Diesel Power Plant
The diesel power plant essentially consists of the following components:
- Diesel engine
- Air filter and supercharger
- Exhaust system
- Fuel system
- Cooling system
- Lubricating system
- Starting system
- Governing system.
#1 Diesel Engine
This is the most important part of a diesel power plant. The engines are divided into two and four-stroke categories. In order to develop power, engines are typically directly coupled to the generator.
In diesel engines, compressed air is introduced into the cylinder. Fuel is injected at the end of the compression stroke. As the fuel burns, expanding gases from the fire exert force on the piston. The generator and engine shaft are directly connected. The burned gases are released into the atmosphere after combustion.
#2 Air Filter and Supercharger
The function of the air filter is to remove the dust from the air which is taken by the engine. The use of the supercharger is to increase the pressure of the air provided to the engine to increase the power of the engine.
#3 Exhaust System
This includes the silencers and connecting ducts. The temperature of the exhaust gases is sufficiently high, therefore, the heat of the exhaust gases may be used for heating oil or air supplied to the engine.
#4 Fuel System
The storage tank, fuel pump, fuel transfer pump, strainers, and heaters are all components of the fuel system. The pump draws diesel from the storage tank and delivers it to the small day tank via the filter. The day tank provides the engine with the fuel it needs each day.
Typically, the day tank is positioned high so that diesel flows to the engine by gravity. The fuel injection pump filters diesel again before injecting it into the engine.
The fuel injection system is responsible for the following tasks.
- Filter the fuel.
- Measuring the proper amount of fuel to inject.
- Count the number of injections.
- Control the fuel supply.
- Ensure precise atomization of fuel oil.
- Make sure the fuel is evenly distributed throughout the combustion chamber.
Depending on the load on the plant, fuel is supplied to the engine.
#5 Cooling System
The temperature of the fuel burning inside the engine cylinder ranges from 1500 to 2000 degrees Celsius. Water is pumped around the engine to lower this temperature. The water surrounds (water jackets) the engine, and the moving water transfers heat from the cylinder, piston, combustion chamber, etc.
The heat exchanger is used to transfer the hot water that is leaving the jacket. The raw water that is circulated through the heat exchanger carries the heat away and cools it in the cooling tower.
#6 Lubricating System
The lubrication system consists of pipes, coolers, oil pumps, and oil tanks. It is used to lessen friction between moving parts and to prolong the life of engine components like cylinder walls and pistons.
Lubricating oil is cooled before being circulated again after becoming heated from the friction of the moving parts. The oil is pumped into the lubrication system from the lubricating oil tank and then through the oil cooler, where it is cooled by the cold water that is entering the engine. After the moving parts have cooled, the hot oil is returned to the lubricating oil tank.
#7 Starting System
This includes compressed air lanks. The function of this system is to start the engine from the cold by supplying compressed air.
#8 Governing System
This consists of the governor and its function is to maintain the speed of the engine constant irrespective of load on the plant by controlling the fuel supply to the engine according to the load.
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Working of Diesel Power Plant
In a diesel engine power plant, the combination of air and fuel serves as the working medium. During the suction stroke, atmosphere air will enter the combustion chamber under the influence of the injection pump, and fuel will be injected through the injection pump into the combustion chamber.
Due to high compression in the engine cylinders, air and fuel are mixed inside the engine, and the mixture is ignited by the combination of air and fuel.
There are two basic principles that apply to the diesel engine, the first of which is that thermal energy is converted into mechanical energy, and the second of which is that mechanical energy is converted into electrical energy to produce power by means of a generator or alternator.
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Advantages of Diesel Power Plant
The following are the advantages of a diesel power plant:
- Design and installation are very simple.
- Can respond to varying loads without any difficulty.
- The standby losses are less.
- Occupy less space.
- It can be started and put on load quickly.
- No problem with ash handling.
- Requires less quantity of water for cooling purposes.
- Low capital investment
- Requires less operating and maintenance staff.
- More economical lubrication system.
- It can burn a relatively wide range of fuel.
- These plants can be located very nearer to the load centers.
- The cost of the building becomes very low.
- More efficient than the steam power plant.
Disadvantages of Diesel Power Plant
The following are the disadvantages of a diesel power plant:
- High operating cost.
- High maintenance and lubrication costs.
- Diesel unit capacity is limited.
- Noise is a serious problem.
- It cannot supply overloads continuously.
- Overload is not possible.
- Releases unwanted emissions.
- Life is quite small (7 to 10 years).
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Application of Diesel Power Plant
The following are some uses for diesel power plants:
#1 Installation of Plant
The plant is simple to install in a power system network. However, if you take economic factors into account, pant limits can range from 5 MW to 50 MW. These limits are also affected by the load capacity, the availability of fuel, water, and the available space.
#2 Peak Load Plant
To meet peak demand, the diesel power plant is combined with thermal and hydroelectric power plants. It lowers the price of producing one unit of electricity. It is simple to start and stop depending on demand and load variation.
#3 Emergency Plant
The diesel engine can serve as an emergency power source. When grid power is unavailable, the diesel engine serves as a backup plant for emergency situations.
#4 Mobile Plant
The diesel power plant’s small and medium capacity can be mounted on a truck or trailer. This plant can be transported to areas where grid power is unavailable and used as a mobile power source. This plant is also utilized in the event of a power outage.
#5 Stand By Unit
This plant can be utilized along with a hydroelectric power plant as a backup. The diesel power plant runs together with the hydropower plant when the hydropower plant’s water supply is insufficient to meet the demand for electricity.
#6 Small-scale Industrial Power Plant
This plant can be used to temporarily power a small industry where consistent access to power is necessary throughout the day.
#7 Nursery Station
The diesel power plant is used as a temporary solution to supply the electricity in some areas where a grid is not available or any developing area does not have enough load to connect with a grid.
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