Evening star., 1897-02-13
Smoke Prevention.

Scarcely less Interesting, said Mr.. Bryan.
are the results obtained regarding the pre-
vention of smoke. The data from common
furnaces represent them just as they were
being operated in regular service. Those
from the improved settings represent good,
bad and Indifferent devices. They show
that the maximum SMOKE with improved
devices is but little over half that from the
common furnace: while the minimum is re
duced" to an impereeptible figure. AS an
avera ge -theseC agI1res indicate that I'M
proved furnaces have reduced the smoke
fully 50 per cent. If We were to eliminate
from this list all the notably poor devices,
the average of the rest would show re-
duction of from 90 to % per cent or forty
trials OF improved, or so-called "smokeless''
furnaces. during which careful records were
kept of the smoke, three average less than
half of l per cent; six average between
or e-half and per cent; eleven average be-
tween l ard > per cent; seven average be-
tween and 10 per cent; seven average be-
tween 10 and 20 per cent; six average above
20 per cent.
Three EssentiaIs.
Hence it appears that smoke averaging
less than 1 per cent is not only possible,
says Mr.. Bryan. but is being secured regu-
larly in everyday service in quite a num-
Der of large steam plants in the vicinity of
st. Louis.
In designing boiler plant to give the
lest results under all conditions of service.
with low-grade fuels. the author recon-
mended the following desirable features
should be kept In mind:
A. Ample draft. one inch of water or
zen more. Good results cannot be secured
with drafts less than one-half inch. Good
draft and thick beds of fuel permit the high
firebox temperatures which We have found
absolutely necessary.
B. Large ratio of heating to crate sur-
face. SO that while burning coal at high
ate per square foot Of crate per hour
there is sufficient heating surface to reduce
the temperature of the fiue gases to 45Oo
Fahrenheit or less.
c. The combustion chamber should. if
possible, be separate from the heating sur
faces, SO as to avoid their cooling effect.
1t should be quite deep-thirty inches or
more.
Gases and Draft.
To secure the very highest results, the
gases. after leaving the boiler-heating sur
faces at not exceeding 500 degrees Fahr.,
should be passed through feed-water econ
omizers and thence through airhea ters.
The feed water. leaving the ordinary ex-
haust-heater at a little above 200 degrees
Fahr may be raised to over 300 degrees in
the economizer, and the heated gases re-
duced 10 80 degrees or less. This reduction
In temperature, OF course, DESTROYS the use
fulness Of these gases draft producers
unless the chimney is very tall. The draft.
icWcFeT, Cali De UeiteT produced by eX-
haust fans. which draw the air through
and out of the furnace and economizer. and
discharge the gases at such a height above
the roof that they will not be objections
bic. thus doing away entirely with the ne
cessity for high chimneys. Still better
economy may be secured by placing air
heaters in the smoke flue beyond the fan.
or between 1t and the economizer Through
these the air. entering the ash pit for pllr-
poses of combustion. may be drawn. so
that the heated gases are finally discharg
ed at a temperature hut a little above that
OF the atmosphere, The speed of the fan
lator, which intfeases the speed of the ram
engine as the steam pressure drops and
reduces 1t as the pressure Increases. thus
performing allr the functions of an auto
experimental IF untitled. but has aireaSv
been adopted ihI numerous large plants.