The Flow Of Gases In Furnaces

DESIGN OF OPEN-HEARTH FURNACES

229

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.

Required
Available from

for
Products of

Heating
Combustion

Gas
Air
Gas
Air

Checker
Checker
Checker
Checker

Temp, top of checkerwork, degrees. . .
200
1200
1700
1700

Temp, bottom of checker, degrees ....
600
300
800
600

Temp, increase or decrease, degrees. . .
600
900
900
1100

Heat capacity in calories at. ... 1700°

4140
4140

(Based upon 100 molecular %™o
960
1700
1750

volumes of the gas burnt • 0 from curve of Fig. 183) . .
oUU
450
480

1250

Heat in calories per 100 molecular

volumes of gas burnt to be given or

absorbed from checkerwork ........
510
1220
2390*
2890*

Heat in calories per cubic meter of gas

burnt to be given out by or absorbed

by checkerwork
228.5
546.6
1071*
1295*

* 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: