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Full text of "The Flow Of Gases In Furnaces"

T

76         APPLICATION OF THE  LAWS  OF  HYDRAULICS
|    f f                                          According to the composition of the gas and the amount of
I    * 11                                     excess air, there will be obtained different quantities of the products
f,   ] I '                                  of combustion, per kilogram of coal.
Ill                                        By computation it can be shown that one of the best grades of
coal mined in the Donietz basin (central Russia) W requires for the
combustion of 1 kg of coal an air supply of 8 m3 71, and the volume
of the products of combustion is 9 m3 04, theoretical or neutral
combustion.
According to the above, the volume of gases given off by the
combustion of 1 kg of this coal will be
Theoretical air supply.................    9 m3  04
1.25 times theoretical air supply........   11       22
1.50                                           ........   13       39
1.75                                           ........   15       59
2.00                                           ........   17       75
!!?   :
For producer-gas-fired furnaces, 1 kg of coal gives about
5 m3 22 of producer gas. With a blower combining the air and
I{   f i                             the steam, this requires 3 m3   16 of air for the primary supply
j\   \ j                              and 5 m3 54 for the secondary air supply.    The volume of the
products of combustion with the theoretical air supply arc 9 m3 71;
and with an air supply of 1.50 times the theoretical volume the
volume of the products of combustion will be 12 m3 54.
Knowing the quantity of combustible which will be used in a
unit of time and the resulting volume of the products of combus-
tion, there is another factor which must be determined: the time
that the products of combustion or hot gases remain in the heating
chamber of the furnace.
f
i}     *     \                                           (i) The average composition of this coal is:
Per cent
C.........................................  84.75
H2........................................    4.80
02.;......................................    4.83
N2........................................    1.44
S.........................................    1.48
Moisture..................................    0.90
Ash.......................................    1.80
For larger quantities of moisture and ash, it would be necessary to correct the
air supply and the products of combustion volumes accordingly.