N Furnace. Fig. 27
Lyswa Furnace. Fig. 28
Dimensions of Hearth ............
16X2. 1 =33 m2 6
13X2 =26 rn2
Production per 24 hours . . .....
f 3,800 pouds
Per sous/re meter
I 62,300 kg 1,860 kg
47,400 kg 1 850 kg
Coal consumed per 24 hours
f 800 pouds
409 pouds -J
Coal consumed per second . ...
I 13,000 kg 0 kg 154
6,700 kg 0 kg 079
Ratio between weight of coal and weight of ingots ..........
21.1 per cent
16 8 per cent
Gas volume per kilogram of coal burned with 50 per cent excess air supply ........
14 m3 04
9 m3 89
Gas, volume burned per second reduced to 0°
Qo = 2m3 16
Qo — 0 m3 78
Gas, volume burned per second at / = 1200° . .......
Q1200 = 4 m3 2
Height of roof above hearth at the right of the strangulation, computed by Yesmann's formula for a temperature of 1200° .........
hizooo ~ 0 m 530
Effective height ..... . ..........
0 m ffgff
Gas, volume per second at t = 700° . Height of roof at chimney or waste gas opening by Yesmann's formula £ = 700°
Q7oo = 7m3697
/J,7QO = () ft). 01
Q700 = 2m3780 &7oo — Om 479
Effective heieht .................
h™ — 0 m 850
" N " works. To what may this greater fuel consumption be
attributed. Evidently to the greater height between the roof
and the hearth of these furnaces.
Why was it found necessary at the " N " works to raise the
roof to a certain height above the hearth, while at the Lyswa works
it was found necessary to lower the roof to accomplish the same
result? An examination of the design of the " N" furnace
(Fig. 27) leads to a negative conclusion. Indeed, according to
Yesmann's formula a furnace will require less combustible wb^n
the roof is closest to the hearth. Accordingly the roof should be
brought down as low as possible.
The hot gases consist of a mixture of air, combustible gases and
the products of their reaction upon each other. The combustion
takes place while the hot gafces are passing through the furnace;
C1) The quality of the coal is not considered in this computation.