CEMP-ET
EI 11C302
1 October 1997
B-5. FLUE GAS. Table B-1 and an ultimate analysis must be used to accurately determine
the amount of flue gas produced by the combustion process. Excess air can be considered as
just passing through. If an ultimate analysis is not available, the mass flow rate can be
estimated by assuming that all of the waste, on an ash-free basis, will be oxidized (water
evaporated) and come out with what was originally combustion and excess air. Although the
chemical combinations have changed, the mass will remain the same. Therefore, the mass
flow rate of the flue gas is the combustible portion of the waste, plus the moisture in the waste,
the theoretical combustion air, the excess air, and the moisture in the air. Table 3-2 gives an
example of flue gas rates for a particular garbage composition and various amounts of excess
air. Normally, the additional flue gas produced from the operation of the auxiliary burners
should be very small and can be ignored. This is not true if the waste is very difficult to burn
and the auxiliary burners are expected to be operating most of the time.
B-6. GAS VOLUMETRIC FLOW RATE. Since air is 78% nitrogen by volume and 76% by
weight, both air and flue gas may be treated the same for volumetric calculations with the only
adjustment being for the moisture content. The volumetric flow rate may be determined based
upon the density of air (temperature, pressure, and moisture content) measured at any specific
point in the process. If an actual average moisture value for the specific geographical area is
not known, the value of 0.013 lbs/lb of dry air may be used. Table B-2 may be used to
perform these calculations.
B-4
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