i STEAM COAL - Clpdigital.org

THE COAL TRADE BULLETIN. 29
ECONOMY IN THE OPERATION OF COAL MINE POWER PLANTS.
By P. ('. WKBBB, M, E.. Pittsburgh.
Copyrighted by F. C. Weber, 1904.
The advantages of the Corliss type of steam
engine over that of any other type of slow speed
engine, have been universally recognized by the
engineering world for many years and when used
as the "power end" of an air compressor, it is
generally recognized that this combination produces
the highest type of air compressor. This
is especially true of the larger sizes of compressors.
This fact has long been taken advantage of in
the mining districts of South Africa, Michigan
and many others, where fuel cost is an important
item. Many of the mines at first acquired a number
of small compressors to supply their different
operations, which they replaced with larger Corliss
compressors soon, as the total capacity warranted
such a change. In many new mines to-day
Corliss compressors are the only type considered
from the start.
The more prominent eoal mines are now beginning
to place the proper value on this type of com
pressor, for the old-time heresy that "fuel costs
nothing and need not be considered" is rapidly
giving way to the more logical view that any
waste is a positive loss and what does the work
for one ought to do it for some one else, and
thereby yield its profits to the producer.
If one mining plant requires from 100 to 150 per
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cent, more coal than another for a given amount
of power, the mine is certainly sacrificing its
profit on the extra fuel burned, for the coal makes
just as good steam under the customer's boilers.
Again, if two to two and one-half times as much
coal is burned for a given amount of power, it
costs the mine $1.50 to $2.00, plus selling profit
on the fuel burned, for what they could obtain in
the more economical type of plant at 75 cents,
which is about the average cost per ton to the