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Full text of "The Flow Of Gases In Furnaces"


68

APPLICATION OF THE LAWS OF HYDRAULICS

i

to sinter it in place unless the flame or hot gases lick the hearth of the
furnace.

As the depth H of the gaseous jet is a function of the tempera-
ture of the immobile gases filling the heating chamber of the open-
hearth furnace, the dimensions have been calculated in the follow-,
ing manner: all of the data from existing furnaces as given in
the table by Professor Pavlow have been used to determine the
' temperature t within the heating chamber at which a jet of flame
or hot gases at 1800 would touch the bottom of the furnace; that
is to say, at which H exactly designates the distance from the sill
of the gas port to the tapping hole.

For the 30-tonne furnaces Nos. 20, 21, 23, 24, 25, for which the
inflow of gas and secondary air at 1000 will be 8 m3 44 of gas and
11 m3 77 of air per second, the dimensions and the results of the
computation are given in the following table:


	
	
	
	
	
	
	Distance

Number of Furnace
	Area of Gas Port
	Velocity of Gas at 1000
	Area of    Air
 Port
	Velocity of Air at 1000
	Inclination of Gas Port
	Inclination of Air Port
	from the Bottom of Gas Port Vertically to Tapping


	
	
	
	
	
	
	Hole


	m2
	m/sec
	m2
	m/sec
	Degrees
	Degrees
	Millimeters

20
	0.275
	29.6
	0.54
	21.8
	15
	38
	1150

21
	0.358
	23.5
	0.57
	20.6
	13
	40
	980

23
	0.440
	18.9
	0.72
	16.3
	33
	33
	980

24
	0.260
	32.4
	0.56
	21.0
	10
	38
	1020

25
	0.320
	26.3
	0.64
	18.4
	15
	41
	1370

Except in Furnace No. 23, the streams of air and gas have
different velocities and different inclinations; the masses of the gas
and of the air are also different.
The jets of air and gas at different inclinations combine in the
flame with the same velocity and inclination. This can be resolved
by the parallelogram of velocities, taking into account the different
densities of the air and the gases.
The average velocity and inclination of the flame may be
obtained graphically by the parallelogram of the velocities of the