Introduction To Power plant Engineering | Steam Power Plant | Diesel Power Plant | Nuclear Power Plant | Gas Power Plant | Hydro Power Plant

A power plant may be defined as a machine or assembly of equipment that generates and delivers a flow of mechanical or electrical energy. The main equipment for the generation of electric power is generator. When coupling it to a prime mover runs the generator, the electricity is generated. The type of prime move determines, the type of power plants.

Following Are The Different Types Of Power plant.

1. Steam power plant

2. Diesel power plant

3. Gas turbine power plant

4. Nuclear power plant

5. Hydro electric power plant

1. Steam power plant

Steam is an important medium of producing mechanical energy. Steam has the advantage that, it can be raised from water which is available in abundance it does not react much with the materials of the equipment of power plant and is stable at the temperature required in the plant. Steam is used to drive steam engines, steam turbines etc.

The different types of systems and components used in steam power plant are as follows :

(i) High pressure boiler

(ii) Prime mover

(iii) Condensers and cooling towers

(iv) Coal handling system

(v) Ash and dust handling system

(vi) Draught system

(vii) Feed water purification plant

(viii) Pumping system

(ix) Air pre heater, economizer, super heater, feed heaters.

2. Diesel power plant

The diesel engine has no spark plug, that it intakes air and compresses it, and that it then injects the fuel directly into the combustion chamber (direct injection). It is the heat of the compressed air that lights the fuel in a diesel engine.

Following Are The Advantages Of The Diesel Engine Power Plant:

1. Very simple design also simple installation.

2. Limited cooling water requirement.

3. Standby losses are less as compared to other Power plants.

4. Low fuel cost.

5. Quickly started and put on load.

6. Smaller storage is needed for the fuel.

7. Layout of power plant is quite simple.

8. There is no problem of ash handling.

9. Less supervision required.

10. For small capacity, diesel power plant is more efficient as compared to steam power plant.

11. They can respond to varying loads without any difficulty.

3. Gas turbine power plant

The gas turbine obtains its power by utilizing the energy of burnt gases and air, which is at high

temperature and pressure by expanding through the several ring of fixed and moving blades. It thus resembles a steam turbine.

Thus, a simple gas turbine cycle consists of

(1) a compressor,

(2) a combustion chamber and

(3) a turbine.

The gas turbine power plants which are used in electric power industry are classified into two

groups as per the cycle of operation.

(a) Open cycle gas turbine.

(b) Closed cycle gas turbine.

4. Nuclear power plant

A nuclear power plant differs from a conventional steam power plant only in the steam generating part. There is no change in the turbo-alternator and the condensing system.

The nuclear fuel which is at present in commercial use is uranium. Scientists say that 1 kg of uranium can produce as much energy as can be produced by burning 4500 tonnes of high grade coal.

To understand how nuclear fission works, refer the below image.

Uranium exists in the isotopic form of U235 which is unstable. When a neutron enters the nucleus of U235, the nucleus splits into two equal fragments and also releases 2.5 fast moving neutrons with a velocity of 1.5*10^7 meters/sec producing a large amount of energy, nearly 200 million electron-volts. This is called “nuclear fission”.

5. Hydro electric power plant

Hydro-electric power plant utilizes the potential energy of water stored in a dam built across the river. The potential energy of the water is used to run water turbine to which the electric generator is coupled. The mechanical energy available at the shaft of the turbine is converted into electrical energy by means of the generator.

Following Are The Advantages:

1. Water is a renewable source of energy. Water which is the operating fluid, is neither consumed or converted into something else..
2. Water is the cheapest source of energy because it exists as a free gift of nature. The fuels needed for thermal, diesel and nuclear plants are exhaustible and expensive.
3. There are no ash disposable problems as in case of thermal power plant.
4. Hydro-plant does not pose the problem of air pollution as in the case of thermal plant or radiation hazards as in the case of nuclear plant.
5. Variable loads do not affect the efficiency in the case of a hydro-plant.
6. Life of hydro-plant is very long (1 or 2 centuries) compared with thermal plant ( 3 to 4 decades). This is because the hydro-plants operate at atmospheric temperature, whereas thermal plants operate at very high temperature (about 500 to 800’c).
7. Hydro plants provide additional benefits like irrigation, flood control, fishery and recreation.
8. The water storage of hydro-plant can also be used for domestic water supply.
9. Auxiliaries needed for the hydro-plant are less compared to thermal plant of equal capacity.
10. It requires less supervising staff.
11. Maintenance cost is low.