United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/SR-96/007 March 1996
4>EPA Project Summary
Experimental Investigation of
PIC Formation During CFC
Incineration
G. Kryder and B. Springsteen
Experiments were conducted to as-
sess (1) the effect of residual copper
retained in an incineration facility on
polychlorinated dibenzo-p-dioxin and
dibenzofuran (PCDD/PCDF) formation
during incineration of non-copper-con-
taining chlorofluorocarbons (CFCs);
and (2) the formation of chlorinated and
aromatic products of incomplete com-
bustion (PICs), including PCDD/PCDFs,
during incineration of CFC recycling
residue and hydrochlorofluorocarbons
(HCFCs). High concentrations of PCDD/
PCDFs (23,800 ng/dscm at 7% O2) mea-
sured in a fiscal year (FY) 91 study
during incineration of dichlorodifluo-
romethane (CFC-12) in the turbulent
flame reactor (TFR) could not be re-
peated in the present study. Repetition
tests conducted in the same facility
under similar operating conditions re-
sulted in PCDD/PCDF concentrations
of 118 ng/dscm at 7% O2. However,
results of the present study suggest
that residual copper retained in an in-
cineration facility possibly promotes the
formation of PCDD/PCDFs during in-
cineration of CFC-12 which does not
contain copper. Tests conducted in the
TFR facility resulted in measured PCDD/
PCDF concentrations of 386 - 454 ng/
dscm at 7% O2 during incineration of
CFC-12 which followed incineration of
copper-containing compounds. These
results suggest that CFCs may best be
incinerated in incinerators that do not
treat any copper-containing waste prior
to CFC incineration, in order to elimi-
nate the possibility that residual cop-
per retained in the incineration systems
could promote PCDD/PCDF formation
during subsequent CFC incineration. In
this study, 1,1-dichloro-1-fluoroethane
(HCFC-141b) and the oily residue gen-
erated during CFC recycling processes
were thermally destroyed without sig-
nificant emissions of volatile organic
PICs and PCDD/PCDFs.
This Project Summary was developed
by EPA's National Risk Management
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
A bench-scale study of the incineration
of CFCs, CFC-12 and trichlorofluorometh-
ane (CFC-11), was conducted in FY 91.
For tests performed in the TRF, a water-
cooled furnace (rated at 20.5 kW) at rela-
tively low flame temperatures (790°C for
the primary flame and 980°C for the sec-
ondary flame), the CFCs were shown to
be consistently destroyed at very high ef-
ficiency (greater than 99.999%); however,
significant levels of chlorinated and aro-
matic PICs were detected. The test facility
in which the FY 91 tests were conducted
was previously exposed to trace metals
including copper during incineration of
metals-containing waste prior to the CFC
incineration study. PCDD/PCDFs were
sampled for and detected at high levels
during a single test condition in this study.
The formation of high levels of PCDD/
PCDFs could have been the result of the
catalytic effect of residual copper in the
test facility remaining after incineration of
the metals-containing waste. Of particular
concern, PCDD/PCDFs were sampled for
and detected at high levels in one test
condition.
Subsequently, additional CFC incinera-
tion tests were performed in T-Thermal's
pilot-scale incinerator (rated at 290 kW) in
FY 92. These tests were conducted at a
high flame temperature (1,090°C) with
water injection into the flame zone for
temperature control. PCDD/PCDFs were
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found at moderate levels in only one test
with a high input of a CFC (69% CFC-11
by weight in fuel oil). PCDD/PCDFs were
not found in other tests with lower CFC
inputs. The avoidance of PCDD/PCDF for-
mation in these tests is possibly due to
the higher temperature and/or water injec-
tion. Also, the pilot-scale incinerator is
equipped with a water-quench tank di-
rectly downstream of the burner to pro-
vide rapid flue gas quenching; flue gases
were quenched from 1,090 to 120°C in
about 0.5 sec. The high flue gas quench-
ing rate may have limited chemical reac-
tions that lead to the formation of PICs in
the flue gas.
Follow-up bench-scale tests were con-
ducted in FY 92, using the controlled tem-
perature tower (CTT) to determine the
effect of flame zone temperature on gas-
phase flame formation and destruction of
PICs during CFC-12 incineration. The ef-
fect of water injection into the flame zone
was also studied. PCDD/PCDFs were not
detected at a high flame zone tempera-
ture (1,200°C), while moderate levels of
PCDD/PCDFs were detected at a lower
flame zone temperature (900°C). Low lev-
els of PCDD/PCDFs were also detected
at the lower temperature with water injec-
tion into the flame zone. Flame zone wa-
ter injection may have a reducing effect
on PCDD/PCDF formation during CFC-12
incineration.
The effect of metal contamination of
CFCs on the incineration emissions was
studied in FY 93. The CFCs evaluated
during all of the previous incineration tests
were unused, reagent grade products;
waste and recycled CFCs were not exam-
ined. CFC refrigerants are likely to have
had long-term contact with heat exchang-
ers made of copper-based alloys. The pos-
sibility exists that some copper may
have been leached from copper alloy tub-
ing by acids which may be formed as the
result of a CFC's degradation. The cata-
lytic properties of copper in PCDD/PCDF
formation are well documented. Test re-
sults indicated that incineration of waste
CFC-11 produced low levels of PCDD/
PCDFs. Significant levels of PCDD/PCDFs
were found when the waste CFC-11 which
was tested was spiked with 300 ppm cop-
per.
Purpose
The purposes of this work were (1) to
further evaluate incineration as one of the
appropriate technologies for the safe dis-
posal of CFCs, including HCFCs and CFC
recycling residues; and (2) to compare
current results with those from earlier work
in order to determine if the earlier high-
dioxin emission results are typical for CFC
incineration or a one-time event. The first
objective of this study was to assess the
effect of residual copper retained in an
incineration facility on PCDD/PCDF for-
mation during incineration of non-copper-
containing CFCs. Therefore, initial work of
the present study was a repetition of the
PCDD/PCDF formation measured in FY
91. This repetition test was performed in
the same water-cooled furnace (TFR) at
relatively low flame temperatures in which
the FY 91 tests were conducted. In fact,
the bench-scale test facility was not in
use between the FY 91 and the present
tests so any residual copper that was
present in FY 91 should have been present
in FY 94. Subsequent to the repetition
test, two additional tests were performed
with more copper injected into the TFR
prior to the CFC-12 incineration to evalu-
ate the effect of residual copper retained
in the TFR on subsequent CFC incinera-
tion. At the beginning of the test, copper-
containing fuel was incinerated in the test
facility, followed by incineration of non-
copper-containing CFC-12 during which
the emissions of PCDD/PCDFs were mea-
sured.
The second objective of this study was
to measure the formation of chlorinated
and aromatic PICs, including PCDD/
PCDFs, during incineration of a CFC re-
cycling residue and a representative
HCFC. The production of CFCs is se-
verely restricted under international agree-
ments and federal regulations. HCFCs
have become more popular as CFC sub-
stitute refrigerants. Incineration may be
an appropriate disposal technology for
HCFCs. Therefore, in the second part of
this study, the formation of PICs and
PCDD/PCDFs during incineration of a
HCFC was investigated. In addition to sub-
stitution of HCFC for CFC, recycling of
CFCs is becoming more popular. Signifi-
cant quantities of residues generated dur-
ing the recycling process require disposal.
Incineration of these residues may be an
appropriate disposal method. However,
preliminary analysis of CFC recycling resi-
dues has shown that they may contain up
to 15 ppm copper, which has been shown
to have a catalytic effect on the formation
of PCDD/PCDFs. Therefore, in the last
part of this study, the formation of PICs
and PCDD/PCDFs during incineration of
a CFC recycling residue was investigated.
Procedure
All experimental testing was conducted
at a test site in Irvine, California. Two
bench-scale combustion research facilities
were utilized in this study. The experi-
mental tests to assess the effect of re-
sidual copper retained in an incineration
facility on PCDD/PCDF formation during
incineration of non-copper-containing
CFCs, including the repetition of the FY
91 tests, were conducted in the TFR used
for the FY 91 study. The experimental
tests to measure the formation of chlori-
nated and aromatic PICs, including PCDD/
PCDFs, during incineration of a CFC re-
cycling residue and a HCFC were con-
ducted in the CTT used for the FY 92 and
FY 93 studies.
The experimental tests in this study con-
sisted of three tasks shown in Table 1.
The primary focus of the experimental
sampling was the measurement of PCDD/
PCDF formation during incineration of
CFC, HCFC, and a CFC recycling resi-
due. During each test, flue gas samples
were collected for analysis of semi-vola-
tile PCDD/PCDFs using EPA Method 23.
During incineration of a HCFC and a CFC
recycling residue, flue gas samples were
collected and analyzed for volatile haloge-
nated and non-halogenated organic PICs
using EPA SW-846 Method 0030 (volatile
organic sampling train). Also, the flue gas
was monitored for other combustion prod-
ucts (O2, CO2, CO, and NO) using a con-
tinuous emission monitor.
Task 1 was a repetition test of the FY
91 high PCDD/PCDF emission experimen-
tal results. The tests were conducted in
the TFR. The TFR facility was not used
for experimental testing after completion
of the CFC incineration study in FY 91;
however, the refractory quarl in the pri-
mary combustion zone had been replaced.
For these tests, the TFR was configured
similarly to the FY 91 configuration. The
primary combustion zone was maintained
at 760 - 870°C, and the secondary was
maintained at 980 - 1,090°C. The Task 2
tests were also conducted in the TFR
facility which was operated in the same
configuration as in the Task 1 tests. Fuel
oil containing copper was fired in the facil-
ity, and an aqueous solution of copper
salt was injected into the facility to simu-
late incineration of copper-containing
wastes. Following this, CFC-12 (~ 9% by
volume in propane) was incinerated, and
the formation of PCDD/PCDFs in the flue
gas was measured at two sampling loca-
tions. Additional copper-containing fuel was
fired in the facility, and then the CFC-12
incineration test was repeated. Task 3 was
designed to measure formation of chlori-
nated and aromatic PICs, including PCDD/
PCDFs, during incineration of a HCFC
and a CFC recycling residue.
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Results and Discussion
Task 1 consisted of three repetition
tests, Tests 1 to 3 (see Table 1). PCDD/
PCDFs were not detected in Test 1, the
TFR system blank, indicating no back-
ground contamination in the propane fuel,
sampling train, recovery agents, or result-
ing from the analytical procedure. Tests 2
and 3 were conducted under similar con-
ditions as the FY 91 test in which high
levels of PCDD/PCDFs were detected. The
two tests were conducted on consecutive
days under similar facility operating condi-
tions in order to measure the repeatability
of the experiment. The high temperature
sample (Location 1 at the afterburner out-
let) for Test 3 was not analyzed due to
loss of sample prior to laboratory analy-
sis. Low levels of PCDD/PCDFs (5.4 ng/
dscm) were detected at the high tempera-
ture sampling location sample collected
during Test 2. The PCDD/PCDF concen-
trations measured at the downstream sam-
pling location (Location 2) were higher
(117.8 ng/dscm for Test 3). However, these
measured PCDD/PCDF concentrations
were much lower than the high levels mea-
sured in FY 91 (23,830 ng/dscm). Excel-
lent combustion conditions were achieved
for all test conditions. In all cases, less
than 50 ppmv of CO, corrected to 7% O2,
was detected in the combustion flue gas.
Prior to Task 2, the TFR facility was
conditioned by incinerating a copper-con-
taining fuel and by injecting a copper-
containing aqueous solution. The
copper-containing fuel was fired in the TFR
primary combustor, and the copper-con-
taining solution was injected into the pri-
mary zone during natural gas combustion.
During combustion of the copper-contain-
ing fuel and injection of the copper-con-
taining solution, the primary combustion
zone of the TFR was fired at approxi-
mately 30 kWand the afterburner was not
fired.
For Task 2 (see Table 1), Tests 7 and 8
were CFC-12 incineration tests after cop-
per had been added into the test facility.
Results show that higher levels of PCDD/
PCDFs were formed under these condi-
tions. In Test 7, the PCDD/PCDF concen-
trations at the afterburner outlet (Location
1) and at the low-temperature sampling
location (Location 2) were 118 and 454
ng/dscm, respectively. During Test 8,
PCDD/PCDF formation was not quite as
high: results indicated 53.8 and 386 ng/
dscm for the afterburner outlet and down-
stream locations, respectively. The major
difference between Tests 7 and 8 was the
elapsed time between copper injection and
CFC-12 incineration which allowed residual
copper to be purged from the TFR. Test 7
commenced 3 hours of propane firing af-
ter injecting copper into the TFR, while for
Test 8, 54 hours of propane firing elapsed
following copper injection prior to CFC-12
incineration.
For Task 3, Tests 4 to 6 were con-
ducted in the CTT (see Table 1). Test 4
was a facility system blank in which only
propane was fired in the facility. During
Tests, HCFC-141bwas incinerated in the
facility at a HCFC/propane concentration
of 7.4%. Finally, during Test 6, CFC recy-
cling residue was incinerated without any
auxiliary fuel. Excellent combustion condi-
tions were achieved for all test conditions,
including incineration of CFC recycling resi-
due with no auxiliary fuel. In all cases,
less than 35 ppmv of CO, corrected to 7%
O2, was detected in the combustion flue
gas.
Volatile PICs, determined from the EPA
SW 846 Method 0030 sampling trains,
were measured for Tests 4 to 6. The con-
centrations of volatile organics in the flue
gas for all three tests were very low. Dur-
ing Test 4 (facility system blank), no vola-
tile organic compounds were measured at
levels significantly higher than the back-
ground levels measured in the field blank.
During Test 5 (HCFC-141b incineration),
chloroform was measured at an average
concentration of 14.5 |ig/dscm. The con-
centrations of acetone and methylene chlo-
ride were 67.9 and 129 |ig/dscm,
respectively; however, the concentrations
of these compounds in the associated field
blank were nearly the same. During Test
6 (CFC recycling residue incineration), no
compounds were measured at significant
concentrations. For the analysis in all
cases, surrogate recoveries were within
acceptable limits.
Test 4 was a facility blank test to mea-
sure the background contamination of
PCDD/PCDFs during propane combustion
in the CTT. A moderate concentration of
(~ 3 ng/dscm) PCDD/PCDF was detected
in the facility blank test, suggesting back-
ground contamination from the propane
fuel, sampling train, reagents, or analyti-
cal procedure. Duplicate analysis was per-
formed to confirm these facility blank
results. The presence of background con-
tamination in the Test 4 measurements
suggests that the Test 5 and 6 results
may also contain background contamina-
tion.
Two Method 23 sampling trains collected
samples simultaneously at the downstream
sampling location during Test 5. Results
of the analysis of these samples indicate
PCDD/PCDF concentrations of 2 and 11
ng/dscm for the two samples. These con-
centrations are relatively low compared to
those from CFC incineration.
CFC recycling residue was incinerated
in Test 6. Two simultaneous Method 23
samples were collected at the downstream
sampling location. The concentrations of
PCDD/PCDFs during these tests were 52
and 61 ng/dscm. These measured con-
centrations are similar to those observed
from incineration of pure CFCs in the pre-
vious study.
Note that the flue gas temperature for
Tests 4 to 6 at the Method 23 sampling
location (Location 2) was approximately
225°C, which is within the PCDD/PCDF
formation "temperature window" of about
200 to 450°C. The residence time be-
tween the 1,450°C flame zone tempera-
ture and this sampling location was
approximately 6.2 sec, more than suffi-
cient time for the de novo synthesis of
dioxins and furans. However, results from
the present study indicate that incinera-
tion of HCFC and CFC recycling residue
generates very low levels of PCDD/PCDF
emissions during this temperature window.
The lack of a sufficient level of copper-
contaminant present in the HCFC and the
CFC recycling residue to promote PCDD/
PCDF formation may be the reason for
the observed low PCDD/PCDF emissions.
Comparable levels of PCDD/PCDF emis-
sions were also observed from incinera-
tion of pure CFC-12 in the FY 92 study.
Conclusions And
Recommendations
High concentrations of PCDD/PCDFs
(23,800 ng/dscm) measured in a FY 91
study during incineration of CFC-12 in the
TFR could not be repeated in the present
study. Repetition tests conducted in the
same facility under similar operating con-
ditions resulted in PCDD/PCDF concen-
trations of 118 ng/dscm at 7% O2.
Residual copper retained in an incin-
eration facility can possibly promote the
emission of PCDD/PCDFs during incin-
eration of CFC-12 which does not contain
copper. Tests conducted in the TFR facil-
ity resulted in measured PCDD/PCDF con-
centrations of 386 - 454 ng/dscm at 7%
O2 during incineration of CFC-12 which
followed incineration of copper-containing
compounds. Previous studies have shown
evidence of PCDD/PCDF formation dur-
ing incineration of chlorinated wastes in
the presence of trace copper in systems
with sufficient residence time in the PCDD/
PCDF temperature formation window. This
promotional effect of copper may limit the
types of waste materials which can be
incinerated prior to incineration of highly
chlorinated CFCs. The present results sug-
-------
gest that CFCs may best be incinerated in
incinerators that do not treat any copper-
containing waste materials prior to CFC
incineration, in order to eliminate the pos-
sibility that residual copper retained in
the incineration systems could promote
PCDD/PCDF formation during subsequent
CFC incineration.
Incineration can be used to destroy 1,1-
dichloro-1-fluoroethane (HCFC-141 b) with-
out generating significant quantities of
volatile organic PICs and PCDD/PCDFs.
Incineration can also be used to destroy
the oily residue (which contains 3 ppm
copper) generated during CFC recycling
without generating significant quantities of
volatile organic PICs or PCDD/PCDFs.
Table 1. Test Matrix
Task 1
Task 2
Task3
Test
Number
1
2
3
7
8
4
5
6
Test
Facility
TFR
TFR
TFR
TFR
TFR
CTT
CTT
CTT
Test
Material
Facility Blank
CFC -12
CFC -12
Fuel oil doped with Cu
followed by CFC-12*
Fuel oil doped with Cu
followed by CFC-12*
Facility Blank
HCFC-141b
CFC Residue
PCDD/F
Sampling
Location 1
# Replicates
0
1
1
1
1
0
0
0
PCDD/F
Sampling
Location 2
# Replicates
2
1
1
1
1
2
2
2
CFC/PIC
Sampling
# Replicates
0
0
0
0
0
3
3
3
Fuel oil doped with copper was fired in the test facility prior to testing. Immediately following, CFC-12 was incinerated in the facility. Manual sampling for
PCDD/PCDF occurred during CFC-12 incineration.
G. Kryderand B. Springsteen are with Energy and Environmental Research Corp.,
Irvine, CA 92718.
C.W. Lee is the EPA Project Officer (see below).
The complete report, entitled "Experimental Investigation of PIC Formation During
CFC Incineration," (Order No. PB96-152186; Cost: $38.00, subject to change)
will be available only from
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
National Risk Management
Research Laboratory (G-72)
Cincinnati, OH 45268
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