India ranks fourth in the world in the production of coal ash as by-product waste after USSR, USA and China, in that order.
Fly ash is fine glass powder, the particles of which are generally spherical in shape and range in size from 0.5 to100 μm.
Studies show that wet disposal of ash waste does not protect the environment from migration of metal into the soil.
In developed countries like Germany, 80% of the fly ash generated is being utilized, whereas in India only 3% is being consumed.
Thermal power plant1
THERMAL POWER PLANT
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
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
COMPONENTS Of Thermal Power
Feed water heater
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
• 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
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
• Dry-handled ash is often recycled into useful
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.
• Water resulting from the cooling system blowdown with a
high salt content and sometimes with free chlorine and
• 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
• 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
• 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
• 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.