CALCULATION OF WEIGHT OF WASTE GASES. HI 



CALCULATION OF WEIGHT OF WASTE GASES FROM 

 ANALYSIS.* 



Two methods of calculating from the analysis by volume 

 of the dry chimney gases the number of pounds of dry chim- 

 ney gases per pound of carbon, or the weight of air supplied 

 per pound of carbon, have been given by different writers. 

 These may be expressed in the shape of formulae as follows : 



nC0 2 +80 

 (A) Pounds dry gas per pound C 



3 ( C Q 4. CO) 



} + C 



(B) Pounds air per pound C = 5. 



Formula A may be derived from the method of computa- 

 tion given in Mr. R. S. Hale's paper on " Flue Gas Anal- 

 yses," Transactions A. S. M. E., vol. XVIII. p. 901, and 

 formula B from the method given in Peabody and Miller's 

 Treatise on Steam-boilers. Both are based on the principle 

 that the density, relatively to hydrogen, of an elementary gas 

 (O and N) is proportional to its atomic weight, and that of a 

 compound gas (CO and CO 2 ) to one half its molecular weight. 

 Both formulae are very nearly accurate when pure carbon is 

 the fuel burned ; but formula B is inaccurate when the fuel 

 contains hydrogen, for the reason that that portion of the 

 oxygen of the air-supply which is required to burn the 

 hydrogen is contained in the chimney gas as H a O, and does 

 not appear in the analysis of the dry gas. 



The following calculations of a supposed case of combus- 

 tion of hydrogenous fuel illustrates the accuracy of formula A 

 and the inaccuracy of formula B : Assume that the coal has 

 the following analysis : C, 66.50; H, 4.55; O, 8.40; N, i.oo; 

 water, 10.00; ash and sulphur, 9.55; total, 100. Assume 



* William Kent in Report of Committee on Boiler-tests, A. S. M. E., 

 1897. 



