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Full text of "The Flow Of Gases In Furnaces"

APPENDIX VIII

DESIGN OF HOT-BLAST STOVES
By A. D. WILLIAMS
A. E. MACCOUN, in his paper before the American Iron and
Steel Institute, May 28, 1915, showed the temperature distribution
and the approximate isotherms for a Cowper stove at the Edgar
Thomson Furnaces. The isotherms, being those taken imme-
diately after the stove went on gas and just before going on blast,
indicate that the hot gases, in cooling, tend to flow through those
passes which lose the most heat, those closest to the shell of the
stove, and that the blast, in heating, tends to pass through the
hottest passes, those in the central portion of the stove. This
distribution follows natural laws and cannot be changed except
by the application of sufficient insulation around the outside of
the brickwork to reduce the amount of heat lost through the shell
of the stove. Changing the height of the bridge wall or the dome
of the stove, or increasing the number of chimney valves, will not
affect this distribution, provided, of course, that the one chimney
valve has sufficient area. Strangulation by insufficient valve area
is a common fault, not only in hot-blast stoves, but in many other
types of furnaces.
In a paper before the American Iron and Steel Institute in
October, 1916, Arthur J. Boynton gave a number of illustrations
of current designs in hot-blast stoves, the number of passes varying
from two to four. This paper and its discussion seemed to indicate
that the laws governing the subdivision of streams of heating and
cooling gases were not clearly understood, and this was also shown
in the stove designs illustrated. The laws governing the flow of
heat and the relationship between the thickness of the wall of the
checker openings and the time required to saturate the heat-
storage capacity of the brickwork are not understood. The
checker wall thickness ranged from 1.5 inches (38 mm) to 3 inches
(75 mm), with variations in pass diameter.
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