DESIGN OF OPEN-HEARTH FURNACES
231
amount of heat given to the checkerwork by the products of
combustion.
The maximum quantity of gas required will be
3.5 (cu m per kg) X 1.25(kg coal) =4.375 cu m per second.
The maximum quantity of air required will be
4.375X1.87 = 8.182 cu m per second.
The maximum volume of the products of combustion will be
4.375X2.68 = 11.725 cu m per second.
These volumes are reduced to zero C. and 760 mm of barometric
pressure.
The average volumes will be as follows:
of gas: 3.5X0.5(kg of coal) = 1.75 cu m per second
of air: 1.75 X1.87 = 3.273 cu m per second
of products of combustion: 1.75X2.68 = 4.69 cu m per second
Reversal Period = t
20 Minutes,
1200 Seconds
30 Minutes,
1800 Seconds
Gas:
Maximum calories=4.375X228.5X2= .
Air:
Maximum calories=4.375X546.6XZ= .
Gas:
Average calories = 1.75 X 228.5 X t = .
Air:
Average calories = 1.75 X 546. 6X t = .
1,200,000
2,871,000
480,000
1,148,000
1,800,000
4,306,000
720,000
1,722,000
Allowing for a range of 200° in the checker brick
and 90 per cent of its weight as effective, the
weight of brick required will be
For gas:
20 min.: 1,200,000-s- (200X0.25X0.90) =.....
30 min.: 1,800,000-K200X 0.25X0.90) =.....
For air:
20 min.: 2,871,000-s- (200X0.25XQ.90) =.....
30 min.: 4,306,000-r (200X0.25X0.90) =.....
26,667kg
63,800 kg
40,000 kg
95,680 kg