United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-94/163 November 1994
EPA Project Summary
Experimental Investigation of
PIC Formation During the
Incineration of Recovered
CFC-11
Bruce Springsteen, Loc Ho, and Greg Kryder
Experiments were conducted to in-
vestigate the formation of products of
incomplete combustion (PICs) during
"recovered" trichlorofluoromethane
(CFC-11) incineration. Recovered CFCs
have been reclaimed from previous ser-
vice (e.g., from refrigerators and air con-
ditioners) and may contain organic and
inorganic (e.g., copper) contaminants.
Tests involved burning the recovered
CFC-11 in a propane gas flame. Com-
bustion gas samples were taken and
analyzed for volatile organic com-
pounds as well as polychlorinated
dibenzo-p-dioxins and dibenzofurans
(PCDD/PCDF).
Test results confirm that incineration
can be used to effectively destroy re-
covered CFC-11; CFC-11 destruction ef-
ficiencies of greater than 99.9999 ("six
nines") were consistently demonstrated
for CFC-11-to-propane molar ratios of
0.06-0.6. Volatile halogenated PICs such
as chloromethane, methylene chloride,
dichlorodifluoromethane (CFC-12), me-
thyl propene, chloroform, carbon tetra-
chloride, and tetrachloroethene, as well
as non-halogenated PICs such as ben-
zene, toluene, and acetone, were de-
tected in the CFC-11 and propane in-
cineration flue gas; although most of
the compounds were detected at levels
comparable to typical hazardous waste
incinerators burning chlorinated
wastes.
At the conditions studied, PCOO/
PCDF were either not detected or de-
tected at low levels (less than 10 ng/
dscm @ 7% O in the dry combustion
gas at standard conditions) when sam-
pling immediately downstream of the
combustion flame zone, indicating no
homogeneous formation mechanisms
within the flame. Additionally, low lev-
els were detected when sampling down-
stream of the flue gas scrubber. How-
ever, high levels of PCDD/PCDF (217
ng/dscm @ 7% O2) were detected down-
stream of the wet scrubber in a test
with recovered CFC-11 that had been
spiked with copper to a concentration
of 300 ppm, thus demonstrating that a
combination of high copper level and
additional gas residence time at a tem-
perature within the PCDD/PCDF forma-
tion window may provide conditions at
which PCDD/PCDF will form. This is
consistent with the results of many pre-
vious bench- and laboratory-scale stud-
ies.
A secondary goal of the study was
to determine the fate of Cl and F. The
results were inconclusive. Inconsistent
mass balances of 29, 200, and 90%
were obtained for tests burning CFCs.
The ratio of chlorine (Cl) to fluorine (F)
in the flue gas samples was consistent
with that of the CFC-11, thus demon-
strating that the Cl and F were being
liberated into the flue gas at equivalent
rates and indicating potential errors in
the sampling methods (leaks, break-
through of the impinger solutions, etc.)
or losses within the sampling or com-
bustor system as reasons for poor
mass balances.
This Project Summary was developed
by EPA's 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).
Printed on Recycled Paper
-------
Introduction
Chlorofluorocarbons (CFCs) are impli-
cated in the depletion of stratospheric
ozone and are also contributors to global
warming. As a result of the Montreal Pro-
tocol and the subsequent national policies
that require phaseout of the use of CFCs
and other ozone depleting substances, the
destruction of considerable quantities of
CFCs may be necessary to reduce cur-
rent inventory levels. Incineration is the
only technology available at a commercial
scale for CFC destruction. However, the
risks associated with CFC incineration
(e.g., its combustion emissions character-
istics) are not well defined.
A few full- and bench-scale studies have
demonstrated that CFCs can be efficiently
destroyed by incineration; however, prod-
ucts of incomplete combustion (PICs)
(such as chlorinated hydrocarbons) may
also be formed during CFC incineration.
The objectives of this work are to further
evaluate incineration as one of the appro-
priate technologies for the safe disposal
of CFCs. Specifically, this study investi-
gates the emissions of PICs and methods
for their control during the incineration of
"recovered" CFCs that have been in pre-
vious service (e.g., in refrigerators or au-
tomobile air conditioners). CFCs for all
the previous incineration tests were un-
used, new commercial-grade products.
Recovered CFCs may have significant
contamination that may lead to formation
of hazardous PICs. Recovered CFCs are
likely to have had long-term contact with
heat exchangers made of copper-based
alloys. Copper may leach from the copper
alloy tubing, particularly if acids are
present. Acids may be formed as the re-
sult of CFC degradation that occurs when
the CFC is exposed to overheated com-
pressors and motors for hermetic units.
This may be of critical importance since
the catalytic properties of copper that lead
to polychlorinated dibenzo-p-dioxin and
dibenzofuran (PCDD/PCDF) formation are
well documented. In addition to the poten-
tial effect of copper, the effect of flue gas
residence time and quenching rate on PIC
formation is studied. A secondary goal is
to determine the fate of fluorine (F) and
chlorine (Cl) through the incineration sys-
tem. Prior investigations have shown that
as little as 20% of the F entering the
combustion system is accounted for in the
flue gas.
Experimental
The recovered trichlorofluoromethane
(CFC-11) is incinerated in a Controlled
Temperature Tower (CTT) combustion fur-
nace. The furnace system is shown in
Figure 1. The CTT is a down-fired furnace
with a 20-cm I.D. and an overall furnace
length of 2.4 m. The reactor entry con-
sists of a 46-cm long quarl that diverges
from 5 cm at the burner to the full 20-cm
I.D. The CTT is equipped with a variable
swirl diffusion burner with axial air injec-
tion. With this burner, primary air is in-
jected axially while secondary air is in-
jected radially through swirl vanes to pro-
vide for fuel and air mixing and a stable
flame. The used CFC-11 delivery system
is also shown in Figure 1. CFC-11, which
has a low boiling point (24°C), is delivered
to the burner as a liquid to ensure that
copper and other solid phase contami-
nants present in the CFC-11 reach the
flame zone. Pressurized nitrogen is used
to drive the CFC-11 to the burner located
at the top of the CTT. In the burner, the
CFC-11 is atomized in a spray nozzle
with a mixture of propane and nitrogen.
Propane, at a firing rate of 20,500 W, is
provided as the primary fuel source. Com-
bustion air is provided through the vari-
able swirl vanes.
A summary of the target test conditions
and measurements taken during each of
the tests is shown in Table 1. For all tests,
flame zone temperature was maintained
constant at about 1,430°C, and the pro-
pane firing rate and air injection rates were
held constant. Testing was conducted in
two phases. Phase I consisted of evaluat-
ing the destruction efficiency (DE) and
flame gas-phase formation of PICs during
the incineration of recovered CFC-11 and
the fate of Cl and F and consisted of four
tests. Test 1 was a "system blank," involv-
ing the sole firing of propane without any
CFC-11 addition, and was performed to
evaluate the background flue gas species
that are inherent to the fuel, system, and
the sampling procedure. Tests 2-4 were
performed with increasing levels of recov-
ered CFC-11 input (0.06, 0.14, and 0.6
CFC-11-to-propane molar ratio). Tests 5-
7 were performed in Phase II. Test 5, an
additional system blank with propane only,
was obtained because of relatively high
background levels of chlorinated PICs de-
tected in the Phase I system blank. Be-
cause Phase I results showed that the
CFC-11 DE was high and that the levels
of PCDD/PCDF and other PICs were low,
the Phase II tests involved spiking the
CFC-11 with copper, to evaluate its effect
on PIC formation, primarily PCDD/PCDF.
Also, samples were taken downstream of
the scrubber to determine the effect of
additional flue gas residence time at tem-
peratures for chemical reactions that may
form PICs.
Flue gas samples were taken for CFC-
11 and other volatile halogenated and non-
halogenated organic PICs using EPA SW
846 Method 0030 (Volatile Organic Sam-j
pling Train), semi-volatile PCDD/PCDF
using EPA Method 23, and for Cl and F
using EPA Method 26. The flue gas was
also monitored continuously for oxygen
(O,), carbon dioxide (CO2), carbon mon-
oxide (CO), nitric oxide (NO), and total
hydrocarbons (THCs), according to EPA-
approved methods. Flame temperature
was measured using a suction pyrometer.
Propane, air, and CFC-11 injection rates
were monitored using rotameters.
The flue gas sampling that was per-
formed for each test is also shown in
Table 1. For some sampling methods,
sampling both upstream and downstream
of the scrubber was performed, as shown
in Figure 1. Method 23 samples were taken
through the bottom port of the CTT, up-
stream of the scrubber, for all tests so
that the flue gas was not exposed to any
metal surfaces and thus allowing for the
possible catalytic formation of PCDD/
PCDF. Additionally, during Phase II, some
tests were performed downstream of the
scrubber to evaluate potential PCDD/
PCDF formation during flue gas cooling.
Method 0030 samples were taken imme-
diately after the flue gas entered the metal
exhaust ducting, upstream of the scrub-
ber during all tests except Test 6, in which|
samples were taken downstream of the!
scrubber. Method 26 samples were taken
upstream of the scrubber during Tests 1,
2, 3, and 4.
As mentioned, for Test 7, the recovered
CFC-11 was spiked with a copper solu-
tion to achieve a total mixture concentra-
tion of 300 ppm copper by weight. This
was done to evaluate the effects of el-
evated copper content in CFC-11 on the
PCDD/PCDF formation.
Results
Individual test conditions, including CFC-
11 -to-propane injection rate, furnace firing
rate, flame stoichiometry, flame tempera-
ture, and flue gas composition (O?, CO2,
CO, THCs, and NO) are summarized in
Table 2. Flame temperatures ranged from
1,340 to 1,480°C. Excellent combustion
conditions were achieved for all test con-
ditions, regardless of the CFC-to-propane
ratio; i.e., <10 ppmv of THCs and <20
ppmv of CO were detected in the com-
bustion flue gas, corrected to 7% O2 at
standard conditions.
Volatile PICs, determined from the EPA
SW 846 Method 0030 sampling trains,
are shown in Table 3 for all tests (given in
jig/dscm @ 7% O2). Although CFC-11 was
detected at quantifiable levels in the flui
gas for the tests burning CFC-11, it waL
detected at relatively low levels (2-20 ng/
dscm). Additionally, for all tests it was
-------
Water Cooled
CFC-11 Delivery Line
CFC-11
Rotameter
CFG Delivery
System
Y V Return
N2 -W-»i Water
/S i
CFC-11
I1 Propane
I N2
CFC-11
(Liquid)
Ice Bath
Water
Pump
Cooling
Water
wirl rr-J
Mr ~~*T^S
.
i
/I
<-i — i
Burner Gun (Water
^, Cooled with Spray
Ol Atomization Nozzle)
r
p_
(
x:
*W\.V.'
VWO
^
^
^
^
L\\\V
1= »
Controlled
Temperature
Tower
- Refractory
_Q. Suction
Pyrometer
Access Ports
(6)
Refractory
- Brick Port
Plugs
EPA Method
EPA SW 846
i/lethod 0030 and
EPA Method 26
H2O-
NaOH
Solution
w
/ }
Venturi
Scrubber
Stack
EPA SW 846
Method 0030 and
EPA Method 23
Induced
Draft Fan
Figure 1. CFC-11 incineration system: CFC-11 delivery system, Controlled Temperature Tower, ventun scrubber/lan/siack, and critical Hue gas
sampling locations denoted by EPA methods.
detected at below the analytical method
practical quantification level. Correspond-
ing destruction efficiencies of CFC-11,
shown in Table 4, are consistently greater
than six nines.
In addition to CFC-11, other chlorinated
PICs were detected, including dichlorodif-
luoromethane (CFC-12) (1-15 ng/dscm),
carbon tetrachloride (2-120 ng/dscm),
chloromethane (0-12,300 ng/dscm),
methylpropene (3-20 ng/dscm), methylene
chloride (30-140 ng/dscm), and chloroform
(3-70 ng/dscm). Non-chlorinated PICs
were also detected, including benzene (2-
14 ^g/dscm), toluene (11-460 ng/dscm),
and acetone (5-85 fig/dscm). There was
no apparent influence of PIC formation
from the CFC-11-to-propane ratio at the
conditions studied (0.06-0.6 molar ratio),
and no apparent effect of recovered CFC
as opposed to new pure commercial grade
as used in previous studies. Note that
these volatile PIC levels are similar to
levels from typical hazardous waste incin-
erators burning chlorinated wastes.
PCDD/PCDF flue gas levels (shown in
ng/dscm @ 7% O2) are given in Table 5.
PCDD/PCDF were not detected in Test 1
(system blank), indicating no background
contamination in the propane combustion
gas, sampling train, recovery reagents, or
resulting from the analytical procedure.
PCDD/PCDF were not detected in Tests
3 and 4 (0.14 and 0.6 CFC-11-to-propane
molar ratio, respectively) with sampling at
the CTT outlet, indicating no homogeneous
gas-phase formation of PCDD/PCDF dur-
ing CFC-11 combustion at the baseline
furnace conditions. Low levels of OCDD
and OCDF were detected in Test 2 (0.06
CFC-11-to-propane molar ratio). The pres-
ence of copper in the recovered CFC-11
had little or no effect on PCDD/PCDF
formation at the conditions of these tests.
Note the low level of copper (0.2 ppm) in
the recovered CFC-11.
Test 6 results upstream of the scrubber
showed again that PCDD/PCDF were not
formed at significant levels in the flame
region, while downstream scrubber sam-
pling results indicated that additional gas
residence time and exposure to the metal-
lined flue gas duct did not promote PCDD/
PCDF formation. Test 7 was conducted
with CFC-11 that was spiked with copper
to a concentration of 300 ppm by weight,
increased from its original 0.2 ppm. Low
levels from sampling results upstream of
the scrubber indicated that the presence
of increased levels of copper in the CFC
did not promote high temperature gas-
phase PCDD/PCDF formation. However,
high levels of PCDD/PCDF (217 ng/dscm
@ 7% O2) were detected in the sampling
train located downstream of the scrubber.
The combination of high levels of copper
with additional gas residence time and
exposure to metal flue gas duct surface in
a temperature range that is conducive to
PCDD/PCDF formation provided conditions
at which PCDD/PCDF may form. The flue
gas entering the scrubber was at a tem-
perature of about 370°C, which is within
the PCDD/PCDF formation "temperature
window" of from 200 to 450°C. This con-
-------
Table 1. Test Conditions and Sampling Schedule
Test Conditions
Flue Gas Sampling Schedule
Phase
I
II
Test
No.
1
2
3
4
5
6
7
CFC-11-to-
Propane
Molar Ratio
0
0.05
0.15
0.6
0
0.15
0.15
CFC
Copper
Spiking
nsf
no
no
no
na
no
yes'
Method 23
(PCDD/PCDF)
U*
X>
X
X
X
np
X
X
D"
np>
np
np
np
np
X
X
Method 0030
(PICs)
U
X
X
X
X
X
np
X
D
np
np
np
np
np
X
np
Method 26
(CI/F)
U
X
X
X
X
np
np
np
'Sampling upstream of wet scrubber.
^Sampling downstream of wet scrubber.
cna - not applicable for tests without CFC.
dx - sampling performed at this location and condition.
'np - sampling not performed at this location.
'Spiked with 300 ppm of copper by weight.
Table 2. Summary of Test Conditions'
Test
No.
1
2
3
4
5
6
7
CFC-11-to-
Propane
Molar Raticf
0
0.06
0.14
0.6
0
0.14
0.14"
Flame
Temperature
(°C)
1,480
1,430
1,370
1,340
1,480
1,430
1,430
02
(vol. %)
8.8
8.8
7.4
7.2
6
7.4
7.4
Flue
C02
(vol.%)
5.3
6.5
8.5
8.3
10.0
8.5
8.5
Gas Composition
CC*
(ppmv)
17
17
19
20
21
19
19
THC°
(ppmv)
2
6
8
10
2
8
8
NO
(ppmv)
68
52
58
39
86
58
58
* For all tests, propane firing rate = 20,510 W, and mass-based SB <
6 (Moles CFC-11)/(Mole propane).
c@ 7% O2 in dry gas at standard conditions.
dCFC-11 spiked with 300 ppm of copper by weight.
1.38.
elusion is consistent with other research
that has shown that residence time in the
post-combustion cooling zone was the pri-
mary factor in PCDD/PCDF formation.
Note that the PCDD/PCDF may have
formed within the wet scrubber; tests im-
mediately upstream of the scrubber would
need to be performed to determine the
exact formation mechanisms.
Table 6 summarized the results of the
EPA Method 26 CI/F testing. Mass bal-
ances (i.e., comparison of the Method 26
sampling train results with those predicted
from the CFC-11 composition and input
rate) were not consistent. For Test 2 (0.06
CFC-11-to-propane molar ratio), the mass
balance is very low for both Cl and F
(about 20%); for Test 3, the mass balance
is high (200%); while for Test 4, the mass
balance is good (80 and 100% for Cl and
F, respectively). The weight ratios of Cl to
F detected in the Method 26 samples
agree well with the theoretical level based
on the composition of CFC-11. Thus, both
F and Cl are liberated into the flue gas at
the same rate. Detection of the expected
ratios of Cl and F in each of the Method
26 trains is an indication that the analyti-
cal results are reliable. Thus, the poor
mass balances for Tests 2 and 3 may be
a result of sampling train leakage, incor-
rect monitoring of sample train flue gas
sampling rates, or losses with the com-
bustor or sampling train systems.
Note that, due to the high levels of acid
gases (HCI and HF) generated during the
combustion of CFCs, all PCDD/PCDF and
volatile PIC flue gas sampling at a loca-
tion upstream of the scrubber required
-------
VOC Species
Dichlorodifluoromethane3
Chloromethane
2-Methylpropene
Vinyl Chloride
Bromomethane
Chloro$thane
Trichlorofluoromethane^
1,1-Dichloroethene
Carbon Disulfide
lodomethane
Acetone
Methylene Chloride
Vinyl Acetate
trans- 1,2-Dichloroethene
2-Methyl-2-Propanol
Hexane
1, 1 -Dichloroethane
2-Butanone
Chloroform
1, 1,1-Trichloroethane
Carbon Tetrachloride
Benzene
1 £-DichSoroethane
Fluorobenzene
2,5-Dimethyl-3-Hexene
2-Chloro-2-Mathytpropane
Heptane
Trichloroethene
1 ,2-Dichloropropane
1,4-Dioxana
Bromodichtoromethane
cis-1-3-Dichloropropene
4-Methyl-2-Pentanone
Toluene
trans- 1,3-Dichtoropropene
1, 1 ,2-Trichloroethane
Tetrachloroethene
2-Hexanone
Dibromochloromethane
Chlorobenzene
Ethyl Benzene
m,p-Xylene
Nonane
O-Xylene
Styrene
Bromoform
Cumene
1,2,3- Trichloropropane
1, 1 ,2,2-Tetrachloroethane
1,4-Oichloro-2-Butene
Pentachloroethane
1 ,3-Dichlorobenzene
1 , 4-Dichlorobenzene
Test
1
8.0
45.9
3.2
< 0.6
2.5
< 0.6
2.3
< 0.6
< 0.6
< 0.6
39.2
142.5
22.2
< 0.6
< 0.6
0.4
< 0.6
0.6
0.2
< 0.6
69.0
3.4
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
377.2
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
0.3
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
Test
2
1.9
1213.0
5.3
< 0.6
5.1
< 0.6
2.0
< 0.6
< 0.6
< 0.6
84.3
142.8
< 0.6
< 0.6
< 0.6
2.5
< 0.6
0.5
18.0
< 0.6
117.4
1.8
< 0.6
< 0.6
< 0.6
< 0.6
0.5
< 0.6
< 0.6
< 0-6
0,4
< 0.6
< 0.6
459.3
< 0.6
< 0.6
0.3
< 0.6
< 0.6
0.5
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
< 0.6
Tesf
3
14.9
1030.3
4.1
< 0.5
2.8
< 0.5
2.1
< 0.5
< 0.5
< 0.5
mo
124.9
< 0.5
< 0.5
< 0.5
4.0
< 0.5
0.5
20.2
< 0.5
38.0
1.7
< 0.5
< 0.5
< 0.5
< 0.5
0.2
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
209.8
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
Test
4
1.3
12308.4
6.1
< 0.5
8.4
< 0.5
2.8
< 0.5
< 0.5
< 0.5
4.7
145.4
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
24.0
< 0.5
57.4
14.6
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
3.8
< O.S
< 0.5
157.8
< 0.5
< 0.5
0.5
< 0.5
1.5
0.8
< 0.5
0.5
< 0.5
< 0.5
< 0.5
0-5
< O.S
< 0.5
< 0.5
< 0.5
<• as
< 0.5
< 0.5
Tesf
5
< 0.5
< 0.5
0.7
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
3.0
0.2
< 0.5
< 0.6
0.7
0.2
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
0.2
0.6
< 0.5
0.2
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
Test
6
10.0
47.3
22.8
< 4.9
< 4.9
< 4.9
19.2
< 4.9
7.0
< 4.9
79.4
144.5
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
10.3
70.6
5.7
95.7
9.0
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
17.6
< 4.9
6.5
25.4
< 4.9
< 4.9
< 4.9
< 4.9
4.9
< 9.6
4.9
3.5
16.9
< 12.8
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
< 4.9
Test
7
1.2
< 0.5
6.5
< 0.5
0.6
< 0.5
5.5
< 0.5
4.0
< 0.5
36.9
38.1
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
3.6
3.2
< 0.5
2.5
10.3
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
11.7
< 0.5
< 0.5
5.6
< 0.5
< 0.5
0.4
< 0.5
0.6
0.5
< 0.5
9.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
Concentrations reported in ng/dscm @ 7% O2 at standard conditions.
< - Concentrations below method detection limit; detection limit used.
'CFC-12.
"CFC-11.
-------
modification of standard sampling and ana-
lytical procedures. However, these modifi-
cations are not believed to affect the con-
clusions of the study; all quality assur-
ance and quality control issues for this
project were met. Further discussion of
these issues is contained in the Quality
Control Evaluation in the full report.
Conclusions
Test results further confirm that incin-
eration can be used to effectively destroy
recovered CFC-11; CFC-11 destruction ef-
ficiencies of greater than 99.9999 ("six
nines") were consistently demonstrated for
CFC-11-to-propane fuel molar ratios of
0.06-0.6. Volatile halogenated PICs (e.g.,
chloromethane, methylene chloride, CFC-
12, methyl propene, chloroform, carbon
tetrachloride, and tetrachloroethene) as
well as non-halogenated PICs (e.g., ben-
zene, toluene, and acetone) were detected
in the CFC-11 and propane combustion
flue gas; although most of the compounds
were detected at levels comparable to haz-
ardous waste incinerators burning chlori-
nated wastes.
At the conditions evaluated, PCDD/
PCDF were either not detected or de-
tected at low levels (<10 ng/dscm @ 7%
O2) when sampling immediately down-
stream of the combustion flame zone, in-
dicating no homogeneous formation
mechanisms within the flame. Addition-
ally, low levels were detected when sam-
pling downstream of the flue gas scrub-
ber. However, high levels of PCDD/PCDS
(217 ng/dscm @ 7% O2) were detected ir
a test downstream of the wet scrubbe
with recovered CFC-11 that had beer
spiked with copper to a concentration o
300 ppm, demonstrating that a combina-
tion of high copper and additional gas
residence time at a temperature within the
PCDD/PCDF formation window providec
conditions at which PCDD/PCDF formed.
This is consistent with the results of othei
bench- and laboratory-scale studies.
Tests to determine the fate of Cl and F
during incineration were inconclusive due
to possible sampling problems or losses
with the combustor or sampling systems
due to the very high levels of acids (thou-
sands of parts per million) in the flue gas.
Table 4. CFC-11 Destruction Efficiencies
Test
No.
2
3
4
6
7
CFC-1 1-to-
Propane
Molar Ratio
0.06
0.14
0.6
0.14
0.14
CFC-11
Destruction
Efficiency
(%)
99.99998
99.99999
99.99999
99.99990
99.99997
Emission Ratio
(ng CFC-11 in Flue Gas
to g CFC-1 1 input)
230
121
35
1076
307
Table 5. Summary of PCDD/PCDF Flue Gas Concentrations
Flue Gas Concentration (ng/dscm @ 7% O.J
Congener
PCDD
TCDD
PeCDD
HxCDD
HpCDD
OCDD
Total PCDD
PCDF
TCDF
PeCDF
HxCDF
HpCDF
OCDF
Total PCDF
Total
PCDD/PCDF
Test 1
CTT'
ncf
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Test 2
CTT
nd
nd
nd
nd
5.5
5.5
nd
nd
nd
nd
2.1
2.1
7.6
Test 3
CTT
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Test 4
CTT
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Test 6
CTT
nd
nd
nd
2.7
nd
2.7
nd
nd
1.6
nd
nd
1.6
4.3
Scrub."
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Test 7
CTT
nd
nd
nd
nd
nd
nd
nd
3.2
nd
nd
nd
3.2
3.2
Scrub.
nd
nd
5.3
11.5
13.3
30.1
50.5
66.6
41.6
10.8
17.9
187.4
217.5
'Sampling at outlet of CTT.
bSamplmg downstream of wet scrubber.
"nd - Not detected in sample (below Method Detection Limit).
-------
Table 6. Fate of Chlorine and Fluorine
Output in Flue Gas
Test
No.
1
2
3
4
CFC-11-to-
Propane
Molar Ratio
0
0.06
0 14
0.6
(Method 26)
Cl
(9/hr)
<1
43
909
1721
F
(9/hr)
<1
8
199
405
Input to Furnace
(CFC-11
Cl
(g/hr)
0
205
464
2210
Feedrate)
F
(3/hr)
0
38
86
411
Input/Output Ratio
Cl
<%)
na*
21
196
78
F
(%)
na
22
231
98
CI/F Ratio
Method 26
(%)
na
515
456
425
CFC-11
(%)
na
537
537
537
"na - Not appropriate for propane-only firing.
-------
Bruce Springsteen, Loc Ho, and Greg Kryder are with Energy and Environmental
Research Corp., Santa Ana, CA 92705.
C. W. Lee is the EPA Project Officer (see below).
The complete report, entitled "Experimental Investigation of PIC Formation During
the Incineration of Recovered CFC-11," (Order No. PB94-214772; 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, NC27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
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PERMIT No. G-35
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$300
EPA/600/SR-94/163
------- |