Control of Volatile Organic Compounds Emissions from Manufacturing

flame burners. Overall, this system makes possible a shorter reaction
chamber while maintaining high efficiency.17
Thermal incinerators used t o burn halogenated VOC's often use
additional equipment to remove the corrosive combustii on products. The
flue gases are quenched to lower their temperature and Fouted through
absorption equipment such as spray towers or liquid ;jet scrubbers to
remove the corrosive gases from the exhaust.18
Packaged, single unit thermal incinerators are available in many
sizes to control streams with flowrates from a few hundred scfm up to
about 50,000 scfm. A typical thermal incinerator built to handle a VOC
waste stream of 850 scm/min (30,000 scfm) at a temperature of 870°C
(1,600°F) with 0.75 second residence time would probably be a refractory-
lined cylinder. With the typical ratio of flue gas do waste gas of
about 2.2, the chamber volume necessary to provide for 0.75 second
residence time at 870°C (l,600°F) would be about 100 m3 (3,500 ft3). If
the ratio of the chamber length to the diameter is 2, and if a 30.5 cm
(1 ft) wall thickness is a1 lowed, the thermal inci netrator would measure
8.3 m (27 ft) long by 4.6 m (15 ft) wide, exclusive of heat exchangers
and exhaust equipment.
3.1.2.1 Thermal Incinerator VOC Destruction Efficiency. The
destruction efficiency of an incinerator can be affected by variations
in chamber temperature, residence time, inl et concentration, compound
type, and flow regime (mixing). Of these, chamber temperature, residence
time, and flow regime are the most important.
When the temperature exceeds 700°C (1,290°F), the oxidation reaction
rate is much faster than the rate at which mixing can take place, so VOC I
destruction becomes more dependent upon the fluid mechanics within the
combustion chamber.19 Variations in in1 et concentration also affect the
VOC destruction efficiency achievable; ki netics calculations describing
the combustion reaction mechanisms indicate much slower reaction rates
at very low compound concentrations. Therefore, at low VOC concen-
tration, a greater residence time is required to achieve a high combustion
effici ency .
Test results show that a VOC control efficiency of 98 percent can
be achi eved consistently for many VOC compounds by we1 1 -desi gned units
and can be met under a variety of operating condi tions:20,21 combustion
I
1