United States
[Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park. NC 27711
Research and Development
EPA/600/SR-93/103 August 1993
EPA Project Summary
Characterization of the Organic
Emissions from the Thermal
Destruction of CFCs
Jeffrey V. Ryan
As a result of the Montreal Protocol,
an International accord Implemented to
reduce the production and use of strato-
spheric ozone depleting substances,
considerable quantities of chlorofluo-
rocarbons (CFCs) and halons may be
accumulated and ultimately require dis-
posal or destruction. Incineration Is a
potential destruction technology; how-
ever, little Is known of the combustion
emission characteristics from CFC In-
cineration. A study has been performed
that characterizes the organic emis-
sions resulting from the pilot-scale In-
cineration of trichlorofluoromethane
(CFC-11) and dlchlorodlfluoromethane
(CFC-12) under varied feed rates. A 293
kW (1 million Btu/h) Incinerator was
made available to the EPA for these
tests. The emissions characterizations
focused on determining the destruc-
tion efficiencies (DEs) and major prod-
ucts of incomplete combustion (PICs)
for each CFC evaluated. Sampling was
performed to screen for volatile and
semlvolatlle organic emission products
Including chlorinated aliphatic*, chtoroben-
zenes, chlorophenols, polychlorlnated
dbenzodfoxins and furans (PCDDs and
PCDFs), and polyaromatlc hydrocar-
bons (PAHs). Results Indicate that five
nines (99.999%) DE can be achieved at
a CFC-11 feed rate as high as 69% by
mass. The formation of volatile and
semlvolatlle organic PICs was minimal.
"Less than" concentrations are pre-
sented for target analytes not detected.
Total PCDD/PCDF emission concentra-
tions did not exceed 140 ng/Nm9. The
Injection of water Into the combustion
zone may Improve the thermal destruc-
tion process.
This Project Summary was developed
by EPA'e Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to announce key find-
ings of the research project that Is fully
documented In a separate report of the
same title (see Project Report ordering
Information at back).
Introduction
Halogenated hydrocarbons such as
chlorofluorocarbons (CFCs) have been
implicated in stratospheric ozone deple-
tion. International accords are in place to
phase out the production and/or use of
these ozone-depleting substances (ODSs)
before the end of the century. Although
some of these ODSs will be recycled, it
will probably be necessary to destroy sub-
stantial quantities of some CFCs to re-
duce current inventories. A United Na-
tions Environment Programme (UNEP)
technical advisory committee was formed
in 1991 to evaluate the most appropriate
ODS destruction technologies. Incinera-
tion was identified as a potentially viable
CFC destruction technology. However, the
combustion emissions from CFC incinera-
tion have not been well characterized.
Characterizing products of incomplete
combustion (PICs) and determining de-
struction efficiencies (DEs) are required to
fully evaluate the viability of incineration
as a CFC destruction technology.
Relatively little information is available
regarding CFC incineration, particularly in
the area of PIC characterizations. Data
have been collected indicating that vari-
ous CFCs have been destroyed effectively
by full-scale incineration. However, infor-
mation regarding PICs is virtually nonex-
istent. EPA's Air and Energy Engineering
Printed on Recycled Paper
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Research Laboratory (AEERL) initiated a
program to evaluate the viability of CFC
incineration, including characterization of
PICs. As part of this program, a bench-
scale study was performed thai characterized
the emissions from tricNorofluoiQmethane
(CFC-11) and dichlorodifluoromethane
(CFC-12) incineration. An emission sample
was collected to screen for pdychlorinated
dbenzo-p-dtoxins (PCDDs) and polychlo-
rinated dibenzofurans (PCDFs). The
screen revealed that substantial quanti-
ties (23.8 ng/Nm» total PCDD/PCOF) of
PCDD/PCDF material were present in the
incinerator emissions. Full-scale CFC in-
cineration emissions data were needed to
substantiate or refute this finding.
Through an agreement with EPA, a pi-
lot-scale incinerator was made available
to evaluate the incineration of CFC-11 and
CFC-12 under conditions representative
of full-scale incineration facilities. Under
this agreement, T-Thermal, Inc., provided
the equipment and labor support to pre-
pare and operate the facility for the CFC
incineration tests. Acurex Environmental
Corporation directed these tests including
coordination of sampling and analytical
efforts.
Objectives
The primary objective of this study was
to characterize organic emissions result-
ing from CFC incineration using a repre-
sentative incineration facility. Particular
emphasis was placed on characterizing
PICs. A secondary objective was to con-
firm or refute the presence of PCDDs/
PCDFs in the incineration emissions at
concentrations similar to those observed
during the previous AEERL-sponsored
CFC incineration study. Should similar
PCDD/PCDF emission concentrations be
observed, the screening of incinerator
emissions for volatile and semivolatile or-
ganic PICs may provide insight into po-
tential PCDD/PCDF formation precursors
or intermediates.
Experimental
The incineration tests were performed
at T-Thermal, Inc.'s Conshohocken, PA,
test facility. The test materials (CFC-11
and CFC-12) were incinerated at varied
feed conditions. Four tests were per-
formed. Table 1 presents the target CFC
feeds for each test. Note the inclusion of
a combustion blank (no CFC incineration)
as a test condition.
Emissions samples were collected for
volatile and semivolatile organics and sub-
sequently analyzed to determine DEs and
screen for PICs. Emissions were sampled
downstream of all pollution control devices.
Scrubber liquor samples were collected to
Table 1. Target CFC Feed Conditions
Test Test Conditions
~1 No.2htetonfy
2 3% (by mass) CFC-12/balance
No. 2 fuel oil
3 3% (by mass) CFC-11/balance
No. 2 fuel oil
4 50% (by mass) CFC-11/balance
No. 2 fuel OH
also screen for semivolatile organic PICs.
T-Thermal collected and provided the data
pertaining to test facility operation includ-
ing, waste and air flows, critical tempera-
tures, continuous emission monitoring
(CEM) data, and CFC feed rates.
The T-Thermal pilot-scale test facility is
a down-fired, turbulent flame incinerator
nominally rated at 293 kW (1 million Btu/
h). A diagram of the test facility is pre-
sented in Figure 1. The incinerator con-
sists of a T-Thermal LV-1.3 high intensity
vortex burner mounted tangentially near
the top of the vertical, refractory-lined in-
cineration chamber. The No. 2 fuel oil and
the CFC waste stream are introduced
through the side mounted burner, while
cooling water is introduced through the
sixially mounted top injector. The cooling
water is injected into the flame region to
maintain a consistent incineration tempera-
ture of 1,093°C (2,000°F).
Hot gases leaving the incinerator pass
through a water-washed downcomer and
bubble up through a pH-controlled water
bath. The saturated gas leaves the quench
tank at approximately 88°C (190°F) and
enters a liquid separating tower prior to
passing to the venturi scrubber for par-
tiiculate removal. An alkaline solution (po-
tassium hydroxide) is added to the quench
tank to neutralize add gases resulting from
CFC destruction. Gases leaving the ven-
turi scrubber pass through another liquid
disentrainment tower prior to exhausting
to a packed column scrubber. The pH-
controlled packed column scrubber neu-
tralizes any remaining acid gases. No in-
duced draft fan is used on the incinera-
tion/pollution control system. Instead, the
gases are directed through the system
under positive pressure. All sampling and
monitoring locations were at the exit of
the packed tower.
Results
The incinerator operational data are
summarized in Table 2. The data con-
tained in this table were provided by T-
Thermal. The summary data presented
are based on the average of the mea-
surements taken over each test period.
The CFC feed rates are presented as a
percentage of the sum of fuel and waste
mass flows. The CFC feed rates obtained
were in accordance with those established
in the original test matrix. However, the
obtained CFC feed rate for the high CFC
feed rate test condition (68.9%) was actu-
ally significantly greater than the targeted
level (50%). The 50% feed rate was ex-
pected to represent the maximum feed
rate likely to be employed.
Five nines (99.999%) DE was achieved
for the CFC-12 low feed rate (2.3%) and
the CFC-11 high feed rate (68.9%). Only
three nines DE was achieved for the CFC-
11 low feed rate (2.9%). The DE for this
test condition may have been affected by
a CFC-11 sampling contaminant CFC-11
was presented in CFC-12 and No. 2 oil
baseline test samples as well as field
blanks.
The addition of water to the combustion
chamber to control burner temperature
may also enhance the thermal destruction
of CFCs. The addition of water would re-
sult in an increase in hydroxyl (OH) radi-
cals. The OH radicals provide a bimolecu-
lar destruction mechanism in addition to
unimolecular bond rupture decomposition.
Very few volatile PICs were present in
the baseline, low feed rate CFC-12, and
low feed rate CFC-11 test conditions. Many
of the PICs present were at or near practi-
cal quantifiable levels. The CFC-11 high
feed rate test condition did reveal several
PICs in substantial concentrations. Chlo-
roform was present at a relatively high
concentration (1,500-1,600 ng/Nm3). Car-
bon tetrachbride was also evidenced but
at a much lower concentration (170 jig/
Mm3). Unexpectedly, the most prevalent PICs
were brominated. Bromodtchloromethane,
dbromochloromethane, and titxornomethane
(bfomoform) were the three most prevalent
PICs present. The presence of these PICs
is surprising because no source of bro-
mine was identified in the fuel and/or waste
feed.
PCDDs and/or PCDFs were detected in
all samples collected. However, the
masses of PCDD/PCDF material present
in most of the test samples were at or
near levels present in field blanks. The
data are more than sufficient to provide a
quantitative comparison with PCDD/PCDF
emission concentrations observed during
the previous AEERL bench-scale study.
Total PCDD/PCDF emissions measured
in this study were a factor of 100 less
than those observed earlier. It is difficult
to determine if PCDD/PCDF concentra-
tion is a function of CFC feed rate. Figure
2 graphically depicts total PCDD/PCDF
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Water
Sampling ^^^
Locations x""- p*
Water Separators
Packed Tower Scrubber
Flgun 1. T-Thermal incineration facility.
Table 2. T-Thermal Incinerator Operational Data
Testl
Test 2
Test3
Test 4
Primary Combustion Air Flow-kg/h (Ib/h)
Secondary Combustion Air Flow-kg/h (Ib/h)
Purge Air Flow-kg/h (Ib/h)
Cooling Water Flow-kg/h (Ib/h)
No. 2 Fuel Oil Ftow-kgfr (IMi)
CFC-12 Flow-kg/h (Ib/h)
CFC-11 Flow-kg/h (Ib/h)
Total Fuel/CFC Flow-kg/h (Ib/h)
% CFC of Total Flow
% Excess Air
Firing Rate, kW(MMBtufr)
Incinerator Temperature-0 C (°F)
Oxygen (% dry)
Carbon Dioxide (% dry)
Carbon Monoxide (ppmv dry)
Nitrogen Oxides (ppmv dry)
285.7(629.3)
100.9 (222.3)
8.6 (19.0)
NA
16.2 (35.6)
0.0
0.0
16.2 (35.6)
0.0
25.1
198 (0.676)
1,070 (1,958)
15.9
7.0
0
65
293.7(647.0)
106.4 (234.3)
9.2 (20.3)
14.7(32.4)
19.1 (42.0)
0.5 (1.0)
0.0
19.5 (43.0)
2.3
6.2
234(0.797)
1,092 (1,998)
8.9
10.7
a
43
300.5(661.8)
106.9 (235.5)
9.8 (21.5)
9.1 (20.1)
18.5 (40.8)
0.0
0.5 (1.2)
19.1 (42.0)
2.9
12.0
227(0.776)
1,092 (1,998)
9.0
9.3
10
149
295.3 (650.5)
110.8(244.0)
9.1 (20.0)
8.7(19.2)
18.8(41.4)
0.0
41.6(91.7)
60.4(133.1)
68.9
-6.1
246 (0.839)
1,121 (2,049)
7.3
10.6
15
50
NA = Not available.
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emissions for each test, ft appears that
the high CFC-11 feed rate condition re-
sulted in slightly increased PCDD/PCDF
emissions. PCDD/PCDF analysis of scrub-
ber water samples yielded inconclusive
data. The inconsistent results observed
were likely attributable to a sampling or
analytical contaminant
Method 23 and scrubber water samples
were screened for sem (volatile organic
PICs considered to be PCDD/PCDF pre-
cursors. Essentially all of the target
analytes were not detected. Based on in-
strumentation detection levels, "less than"
emission concentration levels are pre-
sented. No semivolatile organic target
analytes were detected in the scrubber
water samples.
Summary and Conclusions
This study effectively characterizes the
organic emissions resulting from the pilot-
scale incineration of CFCs. CFC-12 and
CFC-11 were thermally destroyed at feed
rates representative of full-scale thermal
destruction facilities (2.3 and 2.9%, re-
spectively). A high CFC-11 feed rate
condition (68.9%) was also evaluated.
Greater than five nines DE (99.999%) was
observed for the CFC-12 and high CFC-
11 test conditions. Only three nines DE
(99.9%) was observed for the low CFC-11
feed rate test condition.
The presence of volatile and semivolatile
organic PICs was screened for. The PIC
screens included target analytes such as
chlorinated aliphatics, chlorobenzenes,
chtorophenols, PAHs, and PCDDs/PCDFs.
Essentially no target PICs were found in
the low CFC feed rate test conditions. For
the high CFC-11 feed rate test condition,
PIC screens indicated that several volatile
organic target PICs as well as several
non-target volatile organic PICs were indeed
present Chloroform, bromodichloromethane,
dibromochloromethane, and bromoform
were emitted in substantial concentrations
(1,500-2,300 ug/Nm3). Carbon tetrachto-
ride was also emitted, but at a lower con-
centration (170 |ig/Nm3). The presence of
brominated PICs was particularly surpris-
ing, as no source of bromine was readily
identifiable; the CFC-11 and fuel oil used
1
No. 2 Fuel Oil CFC-12 Low CFC-11 Low CFC-11 High
Train A
Train B
Average
Figure 2. Total PCDD/PCDF emissions lor each test condition.
during testing were analyzed specifically
for trace bromine. Prior tests on the incin-
eration test facility were suspected as a
residual bromine source.
Essentially all semivolatile organic PICs
target analytes were not detected. This
finding is significant in that chlorobenzenes
and PAHs, PICs identified in a bench-
scale CFC incineration study, were not
detected. A bench-scale study found the
formation of these PICs to be a function
of the halogen/hydrogen ratio.
The PCDD/PCDF emission concentra-
tions measured (2-140 ng/Nm3) were a
factor of 100 less than those reported in
another AEERL-sponsored CFC incinera-
tion study, indicating that the formation of
PCDDs/PCDFs from the incineration of
CFCs may not be as large a concern as
was initially suspected, ft does appear,
however, that increased PCDD/PCDF
emissions were realized at the high CFC-
11 feed rate test condition. The mecha-
nisms involved in PCDD/PCDF formation
from CFC incineration are not fully under-
stood.
The injection of water into the combus-
tion zone to control incinerator tempera-
ture may have several added benefits.
The injection of water may enhance CFC
destruction efficiency. Water injection
would lead to an increase in hydroxyl radi-
cal population, thereby providing a bimo-
tecular destruction mechanism in addition
to unimolecular thermal bond rupture. The
injection of water may also minimize the
formation of PICs. The injected water also
provides an additional source of hydro-
gen. Hydrogen is involved in reactions
that scavenge halogen free-radicals, po-
tentially reducing PIC formation.
£u.S. GOVERNMENT PRINTING OFFICE: 1993 - 750-071/80041
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Jeffrey V. Ryan is with Acurex Environmental Corp.. Research Triangle Park, NC
27709.
C.W.Leeis the EPA Project Officer (see below)
The complete report, entitled 'Characterization of the Organic Emissions from the
Thermal Destruction of CFCs," (Order No. PB93-205 557/AS; Cost: $36.50
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use
$300
EPA/600/SR-93/103
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