FUELS AND COMBUSTION 233
theoretical air used in combustion and (b) the dew point, in degrees centigrade, if the flue
gases are at 2 bars.
8.A fuel oil composed only of carbon, hydrogen, and sulfur is used in a steam generator. The
volumetric flue gas analysis on a dry basis is: CO 2 11.7%, CO 0.440%, O 2 4.002%, SO 2
0.176, and N 2 83-682 Find (a) the fuel mass composition, (b) the air-fuel ratio by mass, (c)
the excess air used, in percent, and (d) the dew point, in degrees centigrade, of the flue gases
if their pressure is 2 bar.
9.A fuel oil burned in a steam generator has a composition which may be represented bv C 14 H 30.
A dry basis flue-gas analysis shows the following volumetric composition: CO 2 11.226%. O 2
4.145% CO 0.863% N 2 83.766%. Write the complete combustion equation for l mol of fuel
and calculate (a) the air-to-fuel ratio by mass, (b) the excess air, in percent, and (c) the mass
of water vapor in the flue gases per unit mass of fuel.
10.A crushed bituminous coal to be used in a fluidized-bed combustion chamber caries in size
between 1/4 and 3/4 in and has a density of 80 Ibm/ft^3. The coefficient of drag when fiuidized
is 0.60. Calculate (a) the minimum gas velocity that fluidizes all the coal if the gas is at
1600°F and 9-atm pressure, and (b) the pressure drop in the bed, psi. Assume that the coal in
the collapsed state has a height of 2 ft and a porosity of 0.25 and that the gas density can be
approximated by that of pure air.
11.10,000 tons of coal are burned in a powerplant per day. The coal has an as-received ultimate
analysis of C 75%, H 2 5%, O 2 6.7%, H 2 O 2.5%, S 2.3 %, N 2 1.5%, ash 7.0%. It burns in
excess air in a fluidized bed combustor. Calculate (a) the mass of calcium carbonate to be
added, in tons per day, and (b) the mass of calcium sulfate to be disposed of, in tons per day.
(The molecular mass of calcium = 40.)
12.Write the chemical formula and sketch the molecule for the following hydrocarbons: (a)
ethane, (b) ethene or ethylene, (c) decane, (d) iso-decane (2,2,3,3 tetramethyl hexane), (e)
pentatriacontane (do not sketch), (f) isobutene (2-methyl propene), (g) I,5-heptadiene (the
numbers indicate the positions of the carbon atoms that precede double bonds), (h) cyclohexane,
(i) naphthalene, (j) 1-methyl napthalene (a methyl radical CH 3 attached to a carbon atom
instead of a hydrogen atom), (k) tetracontane (do not sketch), and (l) dotriacontahectane (do
not sketch).
13.A coal-oil mixture (COM) is composed of the bituminous medium volatility coal listed and a
distillate oil no. 2 that has an ultimate analysis on a mass basis of C 87.2%, H 2 12.5%, S 0.3%,
N 2.