The Flow Of Gases In Furnaces

288 APPENDIX VII

co = the area of the stack in square meters, to be deter-
mined;

KI and *2 = coefficients for velocity at contracted vein and the
ratio of the area of the contracted vein to to;
for the case in hand these may be assumed as unity;
Aair = weight per cubic meter of air; for the case in hand
Z = 30° C. (86° R), 1+0^ = 1.110, 1.293-M.110 =
1 kg 165;

Agaa = weight per cubic meter of gases, Ao = l kg 320,
* = 630° C. (1166° R), 1+^=3.3121, 1.320-
3.312 = 0.399.

The formula may now be written with numerical values, as follows :

42.29 = 1X^/19.62X5.10 1'165

0.399

from which w = 3.07, say, 3 m2 14 (33.10 sq ft), giving a stack
diameter of 2 m 00 (6.5 ft).

t = average temperature of gases in chimney...........'600° (1112° F.)

Qo = volume of waste gases at 0° (32° F.)............... 12 m3 77

451 cu ft

l-j-orf = gas factor for t°................................. 3.202

A0 = specific weight of waste gases per cubic meter....... 1 kg 32

Pounds per cubic foot....................... 0.0821

Q« = Qo(l+oO -12.77X3.202=...................... 40 m3 89

1440 cu ft

Ai = A0* (1+ofl =1.32-5-3.202 = weight per m3......... 0 kg 412

Pounds per cubic foot..................... 0.0257

co =area of chimney bore............................ 3 m2 14

33.10 sq ft

Diameter of chimney bore =..................... 2 m 00

6.5ft

vt — average velocity of gases in chimney = 40.89 -?• 3.14= 13 rn 00 per sec

42.8 ft per sec

£air=temperature of external air, assumed to be......... 30° (86° F.)

Aair = weight per cu m of air at 30° (preceding operation).. 1.165 kg

Pounds per cubic foot..................... 0.0725

Aair-Agas = l. 165-0.412 = differential per m............ 0 kg 753

Draft depression required at base of stack =.............. 42 kg 130

Entry pressure=5.10X0.399 =......................... 2 kg 040

Velocity pressure = 5=A^z;2^20) =0.412(132-*-19.62) =..... 3 kg 550

47 kg 720

First approximation of height of stack=47.720 ^-0.753 =... 63 m 50
208ft