THERMAL POWER PLANT

BY B.NIKHIL KUMAR

What Is Power Plant?

• A power plant or a power generating station, is basically an industrial location that is utilized for the generation and distribution of electric power in mass scale, usually in the order of several 1000 Watts.

• A power plant can be of several types depending mainly on the type of fuel used.

Types of Power Station

1) Thermal power station or a coal fired thermal power plant.

2) Nuclear power generating stations.3) Hydro electric power stations.4) Alternative methods of power generation are a) Solar power generation. b) Geo-thermal power generation. c) Tidal power generation.

WHAT IS THERMAL POWER PLANT ?

• Thermal power plant is also referred as coal thermal power plant and steam turbine power plant.

• Generally in India, bituminous coal, brown coal are used as fuel of boiler.

• To increase the thermal efficiency, the coal is used in the boiler in powder form.

At present 54.09% or 93918.38 MW (Data Source CENTRAL ELECTRICITY AUTHORITY, as on 31/03/2011) of total electricity production in India is from Coal Based Thermal Power Station.

COMPONENTS Of Thermal Power Plant

BoilerTurbineDe aerator Heat ExchangersSuper HeaterEconomizersCondenser Feed water heaterElectrical generatorCooling towers

Efficiency of Thermal Power Station

INSTALLED PLANT CAPACITY AVERAGE OVERALL THERMAL EFFICIENCY

1) upto 1MW 4%

2) 1MW to 10MW 12%

3) 10MW to 50MW 16%

4) 50MW to 100MW 24%

5) above 100MW 27%

The overall efficiency of a thermal power station or plant varies from 20% to 26% and it depends upon plant capacity.

Types of wastes

Bottom Ash Flue gases (so called Fly

ash) Carbon-di-oxide SO2 & NO2 combined

ASH

• The disposal of ash from a large capacity power station is of same importance as ash is produced in large quantities.

• Ash handling is a major problem.• Ash handling system are a) Manual handling b) Mechanical handling c) Electrostatic precipitator

ASH HANDLING EUIPMENT

Precipitator removes the fly ash from the flue gas by electrostatic means (polarization plates/stages).

Fly Ash Silo where fine ashes from ECONOMIZER extracted by vacuum pump are collected. From

there the moistened ash is transported to the ash Pond by trucks.

Clinker Hopper inverted cone-shaped BOTTOM ASH COLLECTOR. From there the moistened ash is transported to the ASH POND by trucks.

Ash Tank/Bin with conveyor collects slag or bottom ash from the FURNACE proper.

Ash Pond outdoor disposal area where the fly and bottom ashes are transported and collected. It consists of perimeter embankment with drainage facilities, regulating reservoir, sedimentation basin and neutralization pit (where waste water is collected and neutralized) before discharge into the sea

TREATMENT OF ASH

• An ash pond is an engineered structure for the disposal of bottom ash and fly ash.

• The wet disposal of ash into ash ponds is the most common ash disposal method,but other methods include dry disposal in landfills.

• Wet disposal has been preferred due to economic reasons.

• Dry-handled ash is often recycled into useful building materials.

UTILISATION OF FLY ASH

• Fly ash bricks.• Fly ash in manufacture of cement(Fly ash is

suitable for use as pozzolana.)• Fly ash in distemper(Distemper manufactured

with fly ash as a replacement for white cement).• Fly ash-based ceramics.• Fly ash as fertilizer.• Fly ash in road construction.

WASTE WATER • Water resulting from the cooling system blowdown with a high salt

content and sometimes with free chlorine and suspended substances.

• Regenerate from the steam generator water treatment; i.e., regenerate resulting from a full demineralization and condensate treatment; with high salt content and an excess of acids.

• Waste water from the flue gas desulfurizer with high salt content and a high concentration of solids.

• Waste water or sludge from the makeup water treatment system for the cooling tower circulation system.

• Filter washing water from the steam generator feed water treatment system and/or pre-cleaning units for makeup water treatment as well as eventual suspended substances from the cooling circulation system filtering plant for the individual water streams.

• Waste water from the ash cooling system with relatively high salt content and suspended substances.

TREATMENT OF WASTE WATER• When an excess of acid or alkali is present,

neutralization will be performed in suitably large storage.

• When the waste water contains precipitatable substances, sedimentation will be done.

• If the waste water has a high salt content, but does not contain either an excess of acids, alkalies or sediment, it is directly discharged.

• No effort is presently made to reduce the amount of ammonium or hydrazine in waste water containing these substances prior to dumping.