incombustible. When O is present, the amount of must be multiplied by 4.76, and this result subtracted from the amount of air required for the inflammable gases. contained in the mixture, as illustrated in the following example:
Example. — Analysis of a certain natural gas shows it to have the following composition:
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Constituents of Gas Per Cent. H 22.0 CH4 67.0 C2H4 5.0 C3H8 1.0 CO 6 CO2 6 N 3.0 O .8 100.0
What volume of air is required for the complete combustion of 1 cubic foot of this gas?
Solution. — Taking the combustible gases in the order given,
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Cubic Feet of Air H requires 2.38 × .22 = .5236 CH4 requires 9.52 × .67 = 6.3784 C2H4 requires (2 + 4⁄4) 4.76 = 3 × 4.76 = 14.28; 14.28 × .05 = .7140 C3H8 requires (3 + 8⁄4) 4.76 = 5 × 4.76 = 23.80; 23.80 × .01 = .2380 CO requires 2.38 × .006 = .01428 Total air required for complete combustion of inflammable gases 7.86828 Subtract, for O contained, 4.76 × .008 = 0.03808 Total air required to burn mixture 7.83020
Hence, each cubic foot of this natural gas requires 7.8302 cu. ft. of air for its complete combustion. Ans.
23. In gas-engine practice, the proportions of C and H, by weight, should be determined, since volumetric measurements usually complicate the determinations to an extent that is very often confusing. When these proportions are known, the quantities of air required for combustion are as shown in the following scheme:
