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Full text of "The Flow Of Gases In Furnaces"

VELOCITY IN  INVERTED WEIRS

55

NORMAL VELOCITY OF GAS FLOW UNDER INVERTED WIER
B = 5 m 00 = width of furnace, corresponding to length of weir.

fc.=
	1 mOO
	0 m 75
	0 m 50
	0 m 30

A =
	3 . 53
	3 . 54
	3 . 57
	3.62

t
	Velocity, Meters per Second —v
			
500°
	3.386
	2.908
	2.344
	1.778

600°
	3.709
	3.185
	2.568
	1.948

700°
	4.006
	3.440
	2.774
	2.104

800°
	4.283
	3.678
	2.965
	2.249

900°
	4.543
	3.901
	3.145
	2.386

1000°
	4.788
	4.112
	3.315
	2.515

1100°
	5.022
	4.312
	3.477
	2.638

1200°
	5.246
	4.504
	3.631
	2.755

1300°
	5.460
	4.688
	3.779
	2.86

1400°
	5.666
	4.865
	3.923
	2.976

1500°
	5.864
	5.036
	4.060
	3.080

1600°
	6.057
	5.201
	4.193
	3.181

1700°
	6.243
	5.361
	4.322
	3.279

1800°
	6.424
	5.516
	4.448
	3.374

Qt=
	5.00?;
	3.75?;
	2.50v
	1.50v

for the drop in temperature of the gases per second. The method
of determining the rate of the drop in temperature is as follows:
The difference between the theoretical calorific intensity, or
temperature, of the combustible and the temperature of the
products of combustion leaving the heated zone is divided by the
time in seconds which the products of combustion remain in
the heated zone. This gives the average drop in temperature of
the gases per second.
For open-hearth furnaces this drop in temperature has been
found to be from 200° to 250° and for large brick kilns with a
spherical roof—down draft—from 70° to 80° per second.
Therefore, taking 1500° as the temperature produced by the
combustion of a coal with an air supply 1.50 times the theoretical
requirements, and 600° as the temperature of the products of com-