DIESEL POWER PLANTS
Diesel power plants produce power from a diesel engine. Diesel electric plants in the range of 2 to 50 MW capacities are used as central stations for small electric supply networks and used as a standby to hydroelectric or thermal plants where continuous power supply is needed. Diesel power plant is not economical compared to other power plants.
The diesel power plants are cheaply used in the fields mentioned below.
1. Mobile electric plants
2. Standby units
3. Emergency power plants
4. Starting stations of existing plants
5. Central power station etc.
LAYOUT OF DIESEL POWER PLANT:
Figure shows the arrangements of the engine and its auxiliaries in a diesel power plant. The major components of the diesel power plant are:
Engine is the heart of a diesel power plant. Engine is directly connected through a gear box to the generator. Generally two-stroke engines are used for power generation. Now a days,
advanced super & turbo charged high speed engines are available for power production.
2) Air supply system
Air inlet is arranged outside the engine room. Air from the atmosphere is filtered by air filter and conveyed to the inlet manifold of engine. In large plants supercharger/turbocharger is used for increasing the pressure of input air which increases the power output.
3) Exhaust System
This includes the silencers and connecting ducts. The heat content of the exhaust gas is utilized in a turbine in a turbocharger to compress the air input to the engine.
4) Fuel System
Fuel is stored in a tank from where it flows to the fuel pump through a filter. Fuel is injected to the engine as per the load requirement.
5) Cooling system
This system includes water circulating pumps, cooling towers, water filter etc. Cooling water
is circulated through the engine block to keep the temperature of the engine in the safe range.
6) Lubricating system
Lubrication system includes the air pumps, oil tanks, filters, coolers and pipe lines. Lubricant
is given to reduce friction of moving parts and reduce the wear and tear of the engine parts.
7) Starting System
There are three commonly used starting systems, they are;
1) A petrol driven auxiliary engine
2) Use of electric motors.
3) Use of compressed air from an air compressor at a pressure of 20 Kg/cm.
8) Governing system
The function of a governing system is to maintain the speed of the engine constant irrespective
of load on the plant. This is done by varying fuel supply to the engine according to load.
Ø Diesel power plants can be quickly installed and commissioned.
Ø Quick starting.
Ø Requires minimum labour.
Ø Plant is smaller, operate at high efficiency and simple compared to steam power plant.
Ø It can be located near to load centres.
Ø Capacity of plant is low.
Ø Fuel, repair and maintenance cost are high.
Ø Life of plant is low compared to steam power plant.
Ø Lubrication costs are very high.
Ø Not guaranteed for operation under continuous overloads.
Ø Noise is a serious problem in diesel power plant.
Ø Diesel power plant cannot be constructed for large scale.
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