Temperature | 4950 Flame Grid
Minimum oxygen content is shown on a wet basis; i.e., as a percent- age of total gases, including water vapor. Most oxygen analyzers report oxygen on a dry basis, so their readings must be corrected for water vapor content. If a potential application does not satisfy the requirements listed above, an alternate method of incineration may be necessary using furnace burners with an external source of combustion air. Check with your North American field engineer. If fume stream contains sufficient oxygen, a Flame Grid can be selected by the following procedure, which assumes combustible contaminants make a negligible contribution to heat required to raise fume stream to incineration temperature. It also assumes 1400°F is adequate for incineration of all combustible contaminants. Basic selection information required:
2. Temperature correction Multiply scfm by Table 1 air capacity factor:
5990 1.29 (for 400 F) = 7727
3. Pressure correction Multiply corrected air capacity by Table 2 factor:
7727 0.65 (for 1.2"w.c.) = 5020 (equiv. scfm air at 60°F inlet and 0.5"w.c. pressure drop)*
4. Select Flame Grid from Table 3: 5020 scfm falls between wide open and minimum settings of 4950-3624 Burner, which is the proper selection. 5. Fuel input requirement from Table 1: 5990 scfm 1390 Btu/h HHV per scfm (at 400°F inlet) = 8,330,000 Btu (approx. 8330 cfh natural gas)
1. Maximum flow rate of fumes, acfm 2. Fume temperature at burner inlet 3. Fume stream pressure drop available across burner.
Table 2. Pressure drop correction factors Air Air
Table 1. Effects of inlet temperature Grid air capacity
Pressure
Factor
Pressure
Factor
drop, "wc (0.5"wc base)
drop, "wc (0.5"wc base)
Gross input (Btu/hr)
Inlet
correction factors
per scfm air
0.2 0.3 0.4 0.5 0.6 0.7 0.8
1.59 1.28 1.12 1.00 0.92 0.85 0.79
0.9 1.0 1.2 1.4 1.6 1.8 2.0
0.75 0.71 0.65 0.60 0.56 0.53 0.50
temperature
(60°F basis)
heated to 1400°F
60°F
1.00
1810 1640 1510 1390 1260 1130 1000
200 300 400 500 600 700 800
1.13
1.21 1.29 1.36 1.43 1.49 1.56 1.62 1.68 1.73 1.79
Table 3. Grid air capacities
870
scfm air (corrected to 60°F inlet and 0.5"w.c. pressure drop)
900
730 590 440 290
1000 1100 1200
Flame Grid designation 4950-0812 4950-1212 4950-1412 4950-2012 4950-1424 4950-2024 4950-2624 4950-3624 4950-2648 4950-3648 4950-5248 4950-7248
Shutter
Shutter
wide open
at min. setting
710
440 660 770
1 060 1 240 1 800 2 500 3 550 4 600 6 400 9 200 12 700 18 400 25 400
EXAMPLE Given: 9900 acfm fume-laden air at 400°F. Available pressure drop 1.2"w.c.
1 100
1 500 2 200 2 850 3 900 5 700 7 900 11 400 15 800
Selection procedure: 1. Convert acfm to scfm, using ratio of absolute temperatures:
(
)
460 + 60 460 + 400
9900 acfm
= 5990 scfm.
Bulletin 4950 Page 3
* See "Fluid Flow" chapter in North American COMBUSTION HANDBOOK for explanation of correction procedure.
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