Environmental Engineering Reference
In-Depth Information
Very few people under the age of
have ever seen a
lump of coal. Until roughly
many homes were
heated with coal and those of us who are old enough
remember what it looks like, and remember with little
pleasure how to run a furnace. I can still remember the
sound of coal hissing and rattling as it slid down a metal
chute into the family basement, and the relief my father
and I felt when he converted our heating system to an oil
burner and we no longer had to shovel the stuff into the
furnace and take out the ashes.
The old
cient coal plants mainly use powdered
coal as a fuel, a different form from what slid down into
my basement. The lumps of coal are ground into some-
thing as
%ef
fine as talcum powder and blown into the furnace
with the correct amount of air to assure proper burning,
generating the steam used to run the electric generators.
A new coal power-plant technology called Ultra-
Supercritical (USC) uses the same powdered-coal fuel
but reaches a higher ef
%) by running
the steam system at higher temperature and pressure than
the standard plants. The technology is new, and there are
not many of these plants around. USC technology has a
slightly older brother called Supercritical (SC) that has an
ef
ciency (about
%, and there are more of these. The
newest technology of
ciency of
is called Integrated Gasi
ca-
tion Combined Cycle (IGCC). Here the coal
rst
turned into a gas which then runs a combined cycle
generator like those used in the best of the gas-
is
red
power plants. While the potential ef
ciency of the com-
bined cycle part of the system is very good, the gasifi-
-
cation process uses
lots of energy and the overall
ef
ciency is more like that of the SC plant. The reason
