Control of Volatile Organic Compounds Emissions from Manufacturing

eing undertaken to determine the effect of higher velocities, in
particular, on destruction efficien;ies.
0.4.2 Discussion of Thermal Incineration ~est Results
Both the theoretical and experimental data concerning combustion
efficiency of thermal incinerators are discussed in this section. A
theoretical consideration of VOC combustion kinetics leads to the
conclusion that at 870°C (1600°F) and 0.75 second residence time,
mixing is the crucial design parameter.14 Pub1 ished 1 iterature indicates
that any VOC can be oxidized to carbon dioxide and water if held at
sufficiently high temperatures in the presence of oxygen for a sufficient
time. However, the temperature at which a given level of voc reduction
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is achieved is unique for each VOC compound. Kinetic studies indicate
that there are two rate-determining (i.e., ow) steps in I
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the oxfdation of a compound. he first slo overall
oxidation reaction is the initial reaction in which the original
compound disappears. The initial reaction of methane (CH4) has been
determined to be slower than that of any other ncmhalogenated organic
compound. Kinetic calculations show that, at 870°C (1600°F), 98
percent of the original methane will react in 0.3 seconds. Therefore,
any nonhalogenated VOC will undergo an initial reaction step within
this time. After the initial step, extremely rapid free radical
reactions occur until each carbon atom exists as carbon monoxide (co)'
immediately before oxidation is complete. The oxidation of CO is the
second slow step. ~a1colatio"s show that, at 870°C (1600"~), 98
percent of an original concentration of CO will react in 0.05 second.
Therefore, 98 percent of any VOC' would be expected to undergo the
initial and final slow reaction steps at 870°C (1600°F) in about 0.35
second. It i s very unlikely that the intermediate free radical reactions
would take nearly as long as 0.4 seconds to convert 98 percent of the
organic molecules to CO. Therefore, from a theoretical viewpoint, any
VOC should undergo complete combustion at 870°C (1600°F) in 0.75
second. The cal cul ati ons on $hi ch thi s conC1;si d; 'is basedr ha"e taken
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into account the low mole fractions of VOC and oxygen which would be
found in the actual system. They have also provided for the great
decrease in concentration per unit volume due ta the elevated temperature.
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