Page 42 - Handbook of Energy Engineering Calculations

By the procedure in step 5, the percent CO , wet basis = 2.265/28.19 =
2
0.0804, or 8.04 percent. The percent CO , dry basis = 2.265/(28.19 − 4.425)
2
= 0.0953, or 9.53 percent.

Related Calculations. Use the method given here when making combustion
calculations for any type of gas used as a fuel—natural gas, blast-furnace gas,
coke-oven gas, producer gas, water gas, sewer gas—from any source,

domestic or foreign, in any type of furnace—boiler, heater, process, or waste-
heat. When the air used for combustion contains moisture, as is usually true,
this moisture is added to the combustion-formed moisture appearing in the
products of combustion. Thus, for 80°F (26.7°C) air of 60 percent relative

humidity, the moisture content is 0.013 lb/lb (0.006 kg/kg) of dry air. This
amount appears in the products of combustion for each pound of air used and
is a commonly assumed standard in combustion calculations.

WOOD FUEL COMBUSTION IN A FURNACE

The weight analysis of a yellow-pine wood fuel is: C = 0.490; H = 0.074; O 2
2
= 0.406; N = 0.030. Determine the weight of oxygen and air required with
2
perfect combustion and with 20 percent excess air. Find the weight and

volume of the products of combustion under the same conditions, and the wet
and dry CO . The flue-gas temperature is 600°F (316°C). The air supplied for
2
combustion has a moisture content of 0.013 lb/lb (0.006 kg/kg) of dry air.

Calculation Procedure:

1. Compute the weight of oxygen required per pound (kilogram) of wood
The same general steps as given in earlier calculation procedures will be
followed; consult them for a complete explanation of each step. Using the
molecular weight of each element, we have