Document 914KrXzoBqLQdeRwkqyjOXmOp
American Society of Heating and Ventilating Engineers Guide, 1930
Table 3. Chimney Sizes for Low-Pressure Heating Boilers and Warm Air Furnaces
Wash Air
Furnace Capacity
in Leader
Pipe Sq. In.
Steam Boiler Capacity Sq. Ft.
op Radia
tion
Hot Water Heater Capacity Sq. Ft.
of Radia
tion
Nominal Dimen
sions OF
FirbClay Lining In.
Rectangular Flub
. Round Flue
Actual Inside Dimensions
of Fire Clay
Lining In.
Actual Area
Sq. In.
Effec- . tive Area
Sq. In.
Inside Diameter
of Lining
In.
Actual Area
Sq. In.
Height in Ft. from Grate
790 590 973 8^x13 1000 690 1140
7x11)^ 81 . 70
10
2 79 ea>uo-
900 1490 13x13 nxxnu 127 99
C.o
900 1490 8Hxl8 6%xl6X iio 100
1100 1820
12 113 gg
1700 2800 13x18 UJ4xl6K 183 156
1940 3200
15 177 gxi
2130 3520 18x18 15^x15^ 248 195
o-s
2480 4090 20x20
298 234
o
3150 5200
18 254 c *w
4300 7100
20 314
4600 7590 20x24
17x21
357 278
^2 c
5000 8250 24x24
21x21
441
g*
5570 9190
24x24s 576 380
5580 9200
22 380
6980 11500
24 452 . a
7270 12000
24x28s 672 468
*T ee rt
8700 14400
28x28s 784 531.
<3 8 3
9380 15500
27 573
10150 16750
30x30s 900 616
10470 17250 11800 19500
28x32s
896 635
30
. U jjj
707 as
14700 24300
33 855 c-fs w
17900 29500
36 1018 <2--ox:
Dimensions are for unlined rectangular flues.
Chimneys recommended for larger boilers 15 to 250 hp. may be pro portioned in accordance with the report made by a joint Committee of the American Boiler Manufacturers Association and Stoker Manufacturers Association and approved by these organizations. The sizes are given in Tables 4, 5 and 6. Chimneys for still greater horsepowers are given in Tables 5 and 6.
CHIMNEYS FOR OIL FUEL1
The requirements for stacks for oil fuels are entirely different from those connected to coal-fired boilers, as there are certain losses through the boiler proper that are eliminated. Gas temperatures entering the stacks are lower for a given capacity, and the volume of gas is less than with coal. The cross-sectional area of the stack may therefore be less. In most instances this may safely be taken as 60 per cent of the area that would be furnished for coal-fired boilers. In determining the height, care must be taken to design a stack that will give a sufficient draft for the maximum requirements of the boiler, but no more. In this way the
*Frora Marks' Mechanical Engineers Handbook.
256
Chapter 14--Chimneys
Table 4. Draft Losses with Forced Draft Stokers and Corresponding Height of Stack for Average Installations (Sea Level)3
100
Furnace Draft**................................................ Friction Loss (Boiler)0--.................................. Friction Loss (Breeching)<i............................. Total Draft Required.--.;:..........................-.... Height of Stack (Ft.)._...................................
- 0.15
0.18 0.10
0.43 80
Rating--Per Cent
150
0.15 0.4 0.10 0.65
112
200
0.15 0.6'5 0.10 0.90
145
250
0.15 0.9 0.10 1.15
178
300
0.15 1.20 0.10. 1.45 220
For boilers from 15 to 250 hp. bAllow 0.15 in. for forced draft and 0.35 in. or higher, depending on rate of combustion and fuel used, for natural draft. Friction loss through boiler varies according to construction.
dAllow 0.05 in. for each right angle bend and 0.1 in. per 100 ft. of length.
Table 5. Diameter of Chimney in Inches for Horizontal Return Tubular Boilers3
Nominal Horsepower
15 20 25 30 35 40 50 60 75 90 100 115 125 150 175 200 210 225 250
Rating--Per Cent
100 150
200
13 14
17
14 16
18
16 18
20
17 19
21
18 20
22
19 21
23
20 23
25
21 24
27
23 26
29
25 28
31
26 29
33
27 31
34
28
32
35
30 34
38
32 36
40
33 38
43
34 38
44
35 40
45 -
36 41
47
The figures in this table are based on the following assumptions:
Rating.........................1........ Efficiency................................... CO*............ _..L........................... Stack Temp. deg. fahr.____
Pounds of gas............................
100%
65%
8%
450 85
150%
65%
. 9%
500
77
200%
63%
10%
550
73
efficiency is safeguarded, and the danger of a draft such as to pull through too large an excess of air is eliminated.
Table 9, adapted from a similar table calculated by C. R. Weymouth {Trans. A. S. M. E., Vol. 34, 1912) and based on actual test data, will be found to give-.satisfactory results under the assumed conditions, as given for stacks with oil-burning boilers.
257