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INTRODUCTION
Clean
Electricity is the brightest side of coal combustion while
Environmental Pollution due to production of huge quantities
of waste ash is the darkest side of electricity generation.
Ash is a waste by-product from "Energy Sector" which starts
from coal extraction and ends up with a consumption of Electricity
as a clean product and associated generation of solid waste
ash as a waste by-product. It is established fact that huge
quantities of fly ash produced by Thermal Plants in our country
is causing pollution of land, water & atmosphere and ultimately
resulting into serious health hazards. While promoting the
maximum utilisation of ash it is equally important to minimise
its production at source i.e.at coal mine. For this , it is
necessary to adopt cradle-to-grave approach regarding entire
energy sector considering direct pollution impacts upstream
& downstream of Thermal Power Stations.
UPSTREAM
CONSIDERATION
Priority wise Key activities of Ash Management are :
- Ash
Minimisation at source i.e. during coal mining
- Ash
Emission Control in Thermal Power Stations
- Ash
Utilisation and
- Ash
Disposal as a last resort.
However,
traditional measures heavily depend on end of-pipe treatment
methods without looking for the essential priorities and their
proportional contributions for mitigation of pollution impacts
downstream.
For reviewing
the complete process, it is necessary to go little upstream
at the birth of ash i.e. at origin of coal.
Indian coal used for the Power Sector has all the following
virtuous qualities.
Coal
Ash Characteristics:
1) Low
iron content in ash, making ash fusion characteristics favourable
for use in Power Plant.
2) High ash fusion temperature 1150 deg. C.
3) Refractory nature of ash with high softening temperature
is advantageous for conventional dry bottom pulverized fired
power plants.
4) SIO2/A1203 ratio of Indian coal is relatively high compared
to U.K. coal which is advantageous from slag viscosity point
of view.
5) Low Chlorine, low toxic trace elements and low Arsenic
content -1000 gm/B.B.tu as against 3600 gm/B.B. tus for U.S.
coal.
6) Low sulphur content below 0.5% so eco-friendly and safe
for storage & transport
7) PFA from coal is light weight, with a particle size 0.5
to 120 um & contains Silica, Alumina, Ferric Oxide & low trace
amounts of heavy metals.
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