MADE BY: AMAY JAIN

• The electric power demand is continuously increasing and it is expected that this demand would be doubled after every 7-10 years due to which there would be rapid rise in pollution of the environment.

• Presently the percentage of pollution caused by electric plants is considerably less (15% of total) which may increase over the years due to increase in the demand of power.

• Elements that cause pollution are called Pollutants.

• In case of thermal power plants, pollutants are defined as emissions that are released from power generating stations and lead to pollution.

• A Thermal Power Plant leads to various types of pollutions like:

1) Air Pollution

2) Water Pollution

• Principal pollutants from a Thermal Power Plant are:

1)Carbon Mono-oxide

2)NOx

3)SOx

4)Fly Ash

5)Particulates formed due to use of fuel additives

Pollutants Effects (On Man)

SO2 Suffocation, irritation of throat and eyes, respiratory, asthma, lung cancer

NOX Irritation, bronchitis, oedema of lungs

H2S Irritation, disease of bone, mottling of teeth, respiratory disease

CO Poisoning, cardiovascular diseases

Particulates (Dust fume mist and soot)

Respiratory diseases like sillcosis, asbetosis

Pollutant Effects (On Vegetation, Material & Animals)

SO2 On Vegetation: destruction of sensitive crops and reduced yieldsOn Materials: Corrosion

H2S On Vegetation: Destruction of cropsOn Animals: Fluorosis in grazing cattle

Particulate (Dust fume mist and soot)

On Material: Soiling and corrosion

• Control of Particulates: To remove the solid particles a majority of

thermal power plants uses one of the following mechanical arresters namely:-

1) Wet Scrubbers 2) Fabric Filters 3) Electrostatic Precipitators

• Control of Sulphur Oxides: Emission of sulphur into the atmosphere is very

harmful therefore it is very important to prevent emission of sulphur which can be done by using two methods:-

1) Removal of Sulphur from the fuel before burning

2) Removal of Sulphur dioxide from the flue gases

• Control of Nitrogen Oxides:

Nitrogen Oxides possess high biological activity and they are poorly soluble in liquids and that’s why they can penetrate deep into lungs and cause harmful diseases and to prevent such problems nitrogen oxides emissions needs to be controlled which can be done by:

1) Reduction in temperature in Combustion zone

2) Reduction in residence time in Combustion zone

3) Increase in equivalence ration in the combustion zone

• An electrostatic Precipitator (ESP) is a highly efficient filtration device that removes fine particles, like dust and smoke, from a flue gas using the force of an induced electrostatic charge minimally impeding the flow of flue gas through the unit.

• Dry ESP: Dry ESPs remove dust from the collection electrodes by vibrating the electrodes through the use of rappers.

• Wet ESP: The basic components of a wet ESP are the same as those of a dry ESP with the exception that a wet ESP requires a water spray system rather than a system of rappers. Wet ESP’s are more efficient then Dry ESP’s.

• Wire Plate ESP: Wire-plate ESPs are by far the most common design of an ESP. In a wire-plate ESP, a series of wires are suspended from a frame at the top of the unit.

• Wire Pipe ESP: In a wire-pipe ESP, a wire that functions as the discharge electrode runs through the axis of a long pipe, which serves as the collection electrode. The weighted wires are suspended from a frame in the upper part of the ESP. The pipes can be cylindrical, square, or hexagonal.