The Flow Of Gases In Furnaces

SIEMENS TYPE EEHEATING FURNACES

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chamber at the level of the hearth; notwithstanding this fact, in
metallurgical plants for smelting copper, lead and some other
metals, a number of old furnaces are still in use which work on the
updraft principle.

Fig. 107 shows a reverberatory copper-refining furnace, the
waste gases from which are removed at the top. In this case
the metal in the bath is in contact with the coolest gases in the
heating chamber, and this very certainly lowers the working

FIG. 107.

temperature of the furnace/1* or results in the expenditure of a
larger amount of fuel than would otherwise be necessary.

XVI. SIEMENS TYPE REHEATING FURNACES
Furnaces of the Siemens type are symmetrical, and the flues
and ports through which the gases pass to the heating chamber
serve also for the removal of the products of combustion. When
reheating furnaces are constructed according to this system, the
head construction of the open-hearth melting furnace is frequently
copied, a procedure for which there is no necessity, owing to the
difference in the purpose for which the heating furnace is used.
This difference affects the operation of the furnace in two
important respects:
1. The temperature to which ingots must be reheated for
rolling or forging does not exceed 1300°, and, for this reason it is
not desirable to direct the jet of flame from the ports directly
upon them. For the open-hearth melting furnace, on the con-
(1) In regard to the method of computation for these furnaces, refer to
T% 21