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DESIGN OF OPEN-HEARTH FURNACES
Total coal consumption = 300X50 = 15,000 kg (for the 500
minutes). The average coal consumption will be 30 kg per
minute, or 0.5 kg per second. The maximum rate of coal con-
sumption will be approximately 1.25 kg per second. This coal
gasified in a producer supplies 3.5 cu m of gas per kilogram of coal
gasified and this gas, burned with 40 per cent excess air, requires
1.87 volumes of air per 1 volume of gas and the products of
combustion will be 2.68 volumes. Fig. 183 shows the heat capacity
and calorific intensity curves of the producer gas, the air supply
and the waste gases, as computed according to the methods of
Mallard and Le Chatelier. These curves are based upon the
combustion or burning of 100 molecular volumes or 2,232 cu m
of the gas fuel under consideration for use in the furnaces.
Temp, top of checkerwork, degrees. . .
Temp, bottom of checker, degrees ....
Temp, increase or decrease, degrees. . .
Heat capacity in calories at. ... 1700°
(Based upon 100 molecular %™o
volumes of the gas burnt • 0 from curve of Fig. 183) . .
Heat in calories per 100 molecular
volumes of gas burnt to be given or
absorbed from checkerwork ........
Heat in calories per cubic meter of gas
burnt to be given out by or absorbed
* These values give the total amount of heat available in 'the products of combustion of
100 molecular volumes or 1 cu m of the gas cooled through the assumed temperature range
of either the gas or the air checker, and which must be divided between the. two checkers.
By assuming that 2 cu m of gas are burned the proportion of
the products of combustion required for the heating of the two
checkers may be arrived at: