Page 372 - Air Pollution Control Engineering

08_chap_wang.qxd 05/05/2004 4:25 pm Page 349
Thermal Oxidation 349

Fig. 2. Thermal incinerator. (From US EPA.)

in this chapter will be based on thermal incineration systems where the emission
streams are preheated.
The incineration of emission streams containing organic vapors with halogen or sulfur
components may create additional control requirements. For example, if sulfur and/or
chlorine are present in the emission stream, the resulting flue gas will contain sulfur
dioxide (SO ) and/or hydrogen chloride (HCl). Depending on the concentrations of
2
these compounds in the flue gas and the applicable regulations, scrubbing may be
required to reduce the concentrations of these compounds. The selection and design of
scrubbing systems are discussed in another chapter.
In this chapter the calculation procedure will be illustrated using emission stream
1 described in Table 1. Example 1 contains worksheets for design and technical cal-
culations (4).
1.2. Range of Effectiveness
Thermal incineration is a well-established method for controlling volatile organic
compound (VOC) emissions in waste gases. The DE for thermal incineration is typically
98% or higher. Factors that affect DE include the three “Ts” (temperature, residence
time, and turbulence) as well as the type of contaminant in the waste gas. With a
0.75-s residence time, the suggested thermal incinerator combustion temperatures
for waste gases containing nonhalogenated VOCs are 1600ºF and 1800ºF, respec-
tively, for 98% and 99% VOC DEs. Higher temperatures (about 2000ºF) and longer
residence times (approx 1 s) are required for achieving DEs of 98% or higher with a
halogenated VOC (4,12).
1.3. Applicability to Remediation Technologies
Storage tanks and surface impoundments are the major sources of organic air emis-
sions at hazardous waste treatment, storage, and disposal facilities, and Superfund sites.
Based on work performed in the development of the benzene waste National Emission
Standards for Hazardous Air Pollutants (NESHAP), wastewater systems are a major
source of benzene emissions from wastes that contain benzene (8–11).