The Flow Of Gases In Furnaces

322

APPENDIX IX

Pittsburgh Coal, . 7 Tests
Anthracite Coal, 7 Tests
Coke, 7 Tests

Av.
Min.
Max.
Av.
Min.
Max.
Av.
Min.
Max.

Carbon in ash, per cent of total carbon ............
7.98
92.02
17.00 76.00 4.00
3.95
82.10
11.00 65.00 1.00
0.13 21.00 4.10 5.00
5.20
17.90
96.05
25.00 85.00 10.00
1.33 131.00 6.10 8.20
7.20
10.76
89.24
16.95 82.53 0.52
2.96
75.20
7.90 68.00 0.30
0.20 20.00 5.70 7.30
5.90
24.80
97.04
31.50 91.50 1.00
2.36 99.50 7.50 10.70
6.60
7.32
92.68
22.00 77.70 0.30
......
3.80
90.45
14.90 71.00 0.10
0.05 15.00 6.10 8.10
6.60
9.55
96.20
29.00 84.90 0.60
1.67 118.60 7.30 10.60
7.60

Carbon burned, per cent of total carbon ......

Per cent of carbon burned to C02.. . burned to CO. . . burned to CH4. . Pressure in ash pit, inches of water. . Pounds of coal per sq ft per hr

Pounds of air per Ib of fuel

Pounds of air per Ib of combustible . . Pounds of air per lb of combustible from gases ......

When the burning gases leave the fuel bed they have an ascen-
sional force, due to their temperature alone, of between 30 and 80
ft per second and are at least 1000° C. hotter than the heating
surface of the boiler. As a result the ascending stream of hot gas
will be very much smaller than the area of the pass and the firebox,
the balance of this area being occupied by cooler eddies of gases
chilled by their contact with the heating surface of the boiler and
the walls of the settings.
A very interesting illustration of the way gas may flow through
a setting was shown on page 709 of Power, Nov. 17, 1914. Mr.
Morgan B. Sniith, however, has his arrows indicating the course
of the gases pointing in the wrong direction. Fig. 169 shows the
correct pointing of the arrows. The hot gases from the fire rise
straight up to the coking arch, and just below this arch the gases
are forced to flow horizontally to the end of the arch where their