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Full text of "The Flow Of Gases In Furnaces"

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be injured by sudden cooling. An open checker is built on the
hearth of the tunnel with these lumps of clay, and on top of this
the brick to be burned are set in a close checker in the upper part
of the chamber. In this way the current of hot gases, which
tends to seek the highest point of the tunnel chamber, is retarded
in its flow and forced downward; the gases cool and produce a
current of colder waste gases over the hearth of the tunnel. The
brick which fill the upper part of the chamber are uniformly

Chambers Cooling

Gas      Chambers Heating

FIG. 92.

heated and burned, but the utilization of their heat for the pre-
heating of the air is very poor and the kiln operates with very
little preheat of the air supply.

The construction and design of ring tunnel kilns is therefore
defective, because the currents of air being heated and those of
gases being cooled have the same direction of flow, whereas it is
necessary that the current which is giving off heat should flow
downward and that the current which is being heated should flow
upward. A ring tunnel furnace is ordinarily unable to satisfy

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Chambers Cooling                             Chambers Heating
FlG. 93.
this  condition,  and  for this  reason  its work  will  always  be
The existing systems of ring chamber furnaces or kilns of the
Mendheim and other similar types are but little more satisfactory
than the ordinary types of kilns. Figs. 92 and 93 show two types
of the Mendheim ring chamber kiln, the latter of these having a
high bridge wall. The outside air enters the system through the
chamber from which the burned ware is being removed, and
passes in succession through all of the chambers which are cooling.