Document omyDVNBBOn0akQXrgrk72YrXg

T a b l e 7. G e n e r a l D a t a of Co m b u s t ib le E le m e n t s an d C om pounds6 b Gas m easured a t 60 F and 30 in . H g . 0 V a lu e fro m N a tio n a l Bureau o f Standard*. 370 CHAPTER 14 1958 Guide 05 CO CO to 05 05 OI co co 05 co o OI 00 0t"5. O 1111 r--I OJ N co o CO hK a o5 -<3 Sa I |. | to o to o to to to o to 05 CO oi oi CO CO ' i--H to CO co tl- <N CO 00 OI 1--< CO Ho o t> 05 on < to <N co co co to to' o t1--o1 CO CO O s to OI 05 o N 05 ~ <N -1' co CO co CO o- CO co on oCO s co co CO co - 5o9 II I I 8 No qO) o(O CO W N CO N M IIII 8 8 3 2 ^ O lO 1-1 ^ 00 CO .05 c0o5 0co5 - o05o i0o5 ISo fc 2-a C-< D a o O Pi $ oo S3 tN.o..N. (8N w 00 O O CO O CD 00 CO CO ID i--i H H i--* 01 . Oil. OI 01 III 3 3 A A5A oo oo oi a o 1--1 s AAA O O o &Q D" -o D O oi o + o + o ^+ Cl 01 OQ 0 q a01? +d 01 +d o do 0o 01 D 0 o H oc O4+0 + t <s o o o q d d oo o co a 5 + + ++d o o o00 flCl CO Dd 0t-- O O CO CO U3 + ++ .+ iS q * ?: d St! tf d 01 Cl ci O oi iii OOOOtejUjOO Oto 3 CO 0a3 03053 C3 aa 0b5O 0tO5 -0U5 .3 Jo33 <s3 aa a 3 OO Fuels and Combustion 371 carbon may unite with oxygen to form carbon monoxide, CO, and some of the hydrogen and hydrocarbon gases may not be burned at all. When carbon monoxide or other combustible gases are present in the flue gases, there is a loss of heat produced per unit of fuel consumed, and a lower combustion efficiency is obtained. Incomplete combustion may result from any or all of the following three conditions;. (1) inadequate air supply, (2) insufficient mixing of air and gases, and (3) a temperature too low to produce ignition or maintain combustion. AIR REQUIRED FOR PERFECT COMBUSTION Air requirements for combustion of solid and liquid fuels are ordinarily expressed in pounds. On the other hand similar requirements for gaseous fuels are usually stated on a cubic foot basis. For solid and gaseous fuels this method of treatment corresponds to the standards of measurement commonly employed by these two industries The weight of air required for perfect combustion per pound of solid or liquid fuel may be calculated after substitution of the proper percentages by weight of the various elements obtained from an ultimate analysis of the fuel in Equation 2. For gaseous fuels see Equation 3 for volume of- air required. Solid or Liquid Fuels: Pounds air required per pound fue. 34.56 TC , / 100 |_3 + \ J0\ S~\ 8/ +8 (2) For Gaseous Fuels: Cubic feet air required per cubic foot gas = 2.39 (CO + Hi) + 9.53 CH, + 16.68 CiH, + 23.82 C,Ht + 30.97 C,H,0 + 11.91 CiH, + 14.29 C,H, + . 7.15 HiS -- 4.78 Oi + 30.47 Uluminants (3) Gaseous fuels may contain a wide variety of components classified as Uluminants, which are not separated by the usual methods of gas analysis. The principal ones in addition to ethylene and acetylene which are included in Equation 3, with the air required per cubic foot of gas are: propylene, 21.44; butylene, 28.58; pentene, 35.73; benzene, 35.73; toluene, 42.88; and xylene, 50.02. Since toluene and xylene are normally scrubbed from the gas before distribution, they may be disregarded in computing air required for a fuel gas. An approximate value of 30.47 (as shown in Equation 3) "ay, therefore, be employed. If ethylene and acetylene are included as illuminanls, it is suggested that the value 19.65 be used. If it is desired to make the gas calculations on a weight basis the equationis expressed as follows: Pounds air required per pound fuel = 2.47 CO + 34.34 Ht + 17.27 CH, + 16.12 CiH, + 15.70 C,H, + 15.49 CMio + 13.30 CiH, + (4) 14.81 CtH, + 6.10 HiS - 4.32 0, Where approximate results only are desired, values appearing in Table 8 "ay be substituted for Equations 2, 3, and 4 ; or the air required for perfect combustion may be estimated by assuming that 0.9 cu ft air is required Per 100 Btu of fuel. Where extreme precision is involved it is suggested that the reader refer 0 scientific literature published on the subject of combustion and related