The Flow Of Gases In Furnaces

174 APPENDIX V

The volume of gas per second is found as follows :
0iooo = 3.3 :5 = 0m366

01000

14

The consumption of coal per second is arrived at as follows:
1 kg of coal gives about 9 m3 00 of gas, and; accordingly:

£ = ;

0.14

= 0 kg 0155 per second=about 55 kg 80 per hour.

9.00
The dimensions of the fireboxes were the same as before,
o,=4XlX0.56 = 2m224,
and corresponded with a fuel consumption of 25 kg of coal per
square meter of grate per hour. The rate of combustion was
rather slow, a condition which is particularly favorable for realizing
theoretical combustion.
The area of the hot gas ports from the firebox:
«i = 4XO. 16X0.32 = 0 m2 20.
The velocity in these parts is low:
^iooo = 0.66 : 0.20 = 3 m 20 per second.
The area of the waste gas ports is
co2 = 16XO.24X0.12 = 0 m2 46.
The velocity in these ports is
^iooo = 0.66 : 0.46 = 1 m 43 per second.
These low velocities make it certain that the waste-gas flue
will receive the coolest gases in the chamber and are also very
favorable to the obtaining of a uniform temperature over the
whole hearth of the muffle.
The height of the waste-gas flue according to Yesmaim's
formula is 0 m 38.
The computation for the chimney was not made, as the
existing chimney was amply sufficient and gave a large margin of
safety, the velocity of the gases at its outlet being very nearly zero.