EPA/600/A-93/257
EVALUATION OF THE IMPACTS OF INCINERATOR
WASTE FEED CUTOFFS
Larry R, Waterland and W. Eddie Whitworth, Jr.
Acurex Environmental Corporation
Incineration Research Facility
Jefferson, Arkansas 72079
ABSTRACT
A series of pilot-scale incineration tests was performed at the Environmental Protection
Agency's (EPA's) Incineration Research Facility (IRF). The tests evaluated whether increased
emissions of a waste's principal organic hazardous constituents (POHCs), hazardous constituent
trace metals, particulate, or HC1 occur when a hazardous waste incinerator is operated sufficiently
close to its permit limits that these permit limits are routinely exceeded, with the result that the
associated waste feed cutoff (WFCO) system repeatedly stops waste feed to the incinerator. In the
tests, a synthetic solid hazardous waste feed (consisting of a POHC liquid mixture combined with
a clay absorbent spiked with arsenic, barium, cadmium, chromium, and lead) was batch-fed to the
rotary kiln incineration system (RKS) at the IRF via a fiberpack drum ram feeder. The POHC
liquid was also fed through the kiln burner. Seven tests were performed. These included two
(duplicate) baseline tests simulating acceptable operation within typical permit conditions, two tests
in which repeated WFCOs were triggered by scrubber system operation out of permit condition,
two tests in which repeated WFCOs were triggered by scrubber exit CO spikes of several hundred
ppm, and a baseline test with reduced waste feedrate. The failures of the venturi/packed-column
scrubber system that were tested were reduced venturi scrubber pressure drop caused by induced
draft fan failure and decreased scrubber liquor flow to the scrubber system caused by recirculation
pump failure. Repeated, large CO spikes were caused by reducing incinerator air flows to below
the levels needed to completely satisfy the oxygen demand in the puff of devolatilized POHC that
occurs with each batch of solid waste charged, and by overcharging solid waste.
Test program results show that none of the tested incinerator operating modes, which
resulted in repeated WFCOs, caused increased POHC, trace metal, or HC1 emissions. POHC
concentrations, emission rates, and destruction and removal efficiencies (DREs) measured in the
scrubber exit flue gas for all repeated WFCO tests were within the range measured for the two
baseline tests. Similarly, trace metal concentrations, emission rates, and distributions among
incinerator discharges for all repeated WFCO tests could not be differentiated from the baseline
tests. Scrubber HC1 collection efficiencies were constant, at 99.8% to 99.9% for all tests. Emission
levels varied only with chlorine feedrate to the RKS.
Scrubber particulate collection efficiencies were relatively constant from test to test, ranging
from 77% to 89%. Scrubber exit particulate levels in the scrubber failure tests were no greater
than in the baseline tests. Scrubber exit particulate levels were increased in the high CO WFCO
tests because of increased scrubber inlet particulate levels at constant collection efficiency.
Overall, test results suggest that the permit requirement to terminate waste feed whenever
a permit-specified operating limit is exceeded is an appropriate protection against increased
incinerator emissions of POHCs, trace metals, and HC1. Only particulate emissions increases,
perhaps to double the baseline, routine operation levels, were measured in these tests. These
increases were not associated with scrubber system failures but, instead, with increased scrubber
inlet particulate from the high CO production modes tested.
Although the test program was performed in the pilot-scale RKS at the IRF with synthetic
hazardous waste feed, past experience has shown that the RKS represents a good model for typical
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at nominally 10% and the target afterburner exit gas temperature was 1,093°C (2,000°F), with flue
gas 02 at nominally 8%. In addition to Tests la and lb, Test 5 was added to the test program as
a low feedrate baseline test. All other conditions for Test 5 were to be the same as for Tests la
and lb with the exception that the synthetic waste per charge and corresponding solid waste
feedrate were reduced.
Test 2 evaluated the incremental HQ and trace metal emissions resulting from WFCO
triggered by low venturi scrubber pressure drop. For this test, an automatic WFCO interlock,
which stopped waste feed when the venturi scrubber pressure drop fell below 4.5 kPa (18 in WC),
was programmed into the RKS process control system. The RKS was set to steady operation at
the conditions of the baseline test. After 20 minutes of normal operation and just after a drum
charge entered the kiln, the venturi scrubber pressure drop was rapidly decreased by shutting off
the scrubber system induced draft fan. This caused the venturi scrubber pressure drop to fall below
the interlock setpoint of 4.5 kPa (18 in WC) and the process control system halted waste feed by
preventing further drum charging and interrupting liquid waste feed to the kiln burner. After
20 minutes, venturi scrubber pressure drop was returned to 6.2 kPa (25 in WC) by restarting the
induced draft fan. As soon as the waste feed permissive signal occurred, liquid and solid waste feed
were restarted. The cycle was repeated after about 40 minutes of returned operation at baseline
conditions. The full cycle was repeated four times so that flue gas samples over four WFCO events
could be collected during the test.
Test 3 evaluated the incremental HC1 and trace metal emissions associated with WFCO
triggered by low scrubber system scrubber liquor flow. Scrubber liquor for both the venturi and
packed-column scrubbers is supplied via a common delivery system. In this test, an automatic
WFCO interlock, which stopped waste feed when the scrubber liquor inlet flowrate to the venturi
scrubber or to the packed-column scrubber dropped below preset limits, was programmed into the
RKS process control system. This test proceeded exactly as Test 2 except that, instead of reducing
venturi scrubber pressure drop, scrubber liquor recirculation to both the venturi scrubber and the
packed-column scrubber was stopped. Scrubber liquor flow to both scrubbers remained off for
20 min, and then was restarted and set to routine operation levels. Waste feed was restarted as
soon as a feed permissive signal occurred. After about a 40-min time interval at returned baseline
operation, the WFCO cycle was repeated. Four cycles were tested over the test day.
Tests 4a and 4b evaluated the incremental emissions associated with WFCO triggered by
elevated CO emissions. For these tests an automatic WFCO interlock, which prevented both liquid
and solid waste feed when instantaneous scrubber exit flue gas CO levels exceeded 100 ppm was
programmed. Thus, if scrubber exit CO levels spiked at above 100 ppm after a solid waste batch
charge, the WFCO interlock terminated liquid waste feed through the kiln burner and prevented
further solid waste charging. After scrubber exit CO levels fell below 100 ppm, liquid and solid
waste feed was restarted and continued until a solid waste batch charge caused another scrubber
exit CO spike.
Two different excessive CO tests were performed. For Test 4a the baseline waste feed
regimen was used. However, air flow to both the kiln and the afterburner was reduced to a rate
that resulted in the average availability of excess air over a charge cycle, but a rate that was
insufficient to satisfy the peak oxygen demand following a solid waste batch charge. A CO spike
of about 1-min resulted. For Test 4b, air flows to both the kiln and afterburner were set to levels
closer to, through still below those used in the baseline tests. However, the solid waste feed charge
size and corresponding feedrate was greater than that used in the other tests, and the solid waste
formulation contained more POHC mixture than that used for the other tests.
Routine scrubber exit CO spikes were indeed experienced during the high CO tests, as
desired. Twenty-two spikes were experienced during the volatile organic emissions sampling period
during Test 4a, seven of which drove the scrubber exit CO monitor to a full-scale reading of
650 ppm. Less frequent CO spikes were experienced for Test 4b. Eleven scrubber exit spikes
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occurred over the volatile organic emissions sampling period during this test. Only two of these
drove the scrubber exit CO monitor to full scale. The other spikes were about 200 ppm or less.
Sampling and Analysis
In addition to obtaining synthetic solid and liquid waste feed, kiln ash, and pre- and post-test
scrubber liquor samples, the sampling protocol for all tests included sampling the flue gas at the
afterburner exit and at the scrubber system exit for trace metals, using the EPA multiple metals
train, and particulate and HC1, using Method 5. In addition, the scrubber exit flue gas was sampled
for the volatile POHCs using, Method 0030. The stack downstream of the secondary APCS was
also sampled for particulate and HC1, using Method 5.
The Method 0030 samples were analyzed for the volatile POHCs, and the multiple metals
train samples were analyzed for the five test trace metals. In addition, the synthetic solid waste
feed, kiln ash, and pre- and post-test scrubber liquor samples were analyzed for the test POHCs
and trace metals,
TEST RESULTS
POHC Analysis Results and DREs
Table I summarizes the measured flue gas concentrations and corresponding emission rates
and POHC DREs for each of the tests. The data in Table I show that toluene concentrations in
the scrubber exit flue gas ranged from 12 to 88 ^g/dscm, tetrachloroethene concentrations ranged
from 1.5 to 14 /ig/dscm, and chlorobenzene concentrations ranged from 1.5 to 9.8 /zg/dscm. The
highest concentrations for all three POHCs were measured in the repeat baseline test, Test lb.
The lowest toluene concentration was measured in the high CO from reduced air flow test, Test 4a.
The lowest tetrachloroethene and chlorobenzene concentrations were measured in Test 3, the
scrubber liquor flow failure test. Flue gas concentrations for these two POHCs were, however,
Table I. Scrubber exit flue gas POHC concentrations and POHC DREs,
Parameter Toluene Tetrachloroethene Chlorobenzene
Test la: Baseline
Scrubber exit gas
Concentration, /ig/dscm
Emission rate, mg/hr
Feedrate, kg/hr
Solid feed
Liquid feed
Total feed
DRE, %
Test lb: Repeat baseline
Scrubber exit gas
Concentration, /ig/dscm
Emission rate, mg/hr
Feedrate, kg/hr
Solid feed
Liquid feed
Total feed
DRE, %
32 3.7 3.0
70 8.0 6,5
3.90 0.86 0.77
4J6 0J3 0J6
8.76 1.69 1.53
99.99920 99.99952 99.99957
88 14 9.8
170 26 19
4.07 1.18 0.83
5.26 0.73 0.90
9.33 1.91 1.73
99.9982 99.9986 99.9989
(continued)
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Table I. Scrubber exit flue gas POHC concentrations and POHC DREs (continued).
Parameter
Toluene Tetrachloroethene Chlorobenzene
Test 2: Scrubber fan failure
Scrubber exit flue gas
Concentration, /xg/dscm 40 7.0 3.6
Emission rate, mg/hr 67 12 6.0
Feedrate, kg/hr
Solid feed 2.47 0.70 0.48
Liquid feed 2.50 0.38 0.43
Total feed 4.97 1.08 0.91
DRE, % 99.9987 99.9989 99.99933
Test 3: Scrubber liquor flow failure
Scrubber exit flue gas
Concentration, /xg/dscm 14 1.5 1.5
Emission rate, mg/hr 27 3.0 3.0
Feedrate, kg/hr
Solid feed 2.73 0.49 0.53
Liquid feed 2.80 0.44 0.47
Total feed 5.53 0.93 1.00
DRE, % 99.99951 99.99967 99.99970
Test 4a: High CO, reduced air flow
Scrubber exit flue gas
Concentration, /xg/dscm 12 1.7 1.7
Emission rate, mg/hr 15 2.1 2.1
Feedrate, kg/hr
Solid feed 3.35 0.59 0.60
Liquid feed 3.28 0.54 Q.53
Total feed 6.63 1.13 1.13
DRE, % 99.99977 99.99981 99.99981
Test 4b: High CO, increased charge mass
Scrubber exit flue gas
Concentration, /xg/dscm 33 4.1 3.8
Emission rate, mg/hr 61 7.5 7.0
Feedrate, kg/hr
Solid feed 8.52 2.07 1.49
Liquid feed 3.30 1.97 1.27
Total feed 11.82 4.04 2.76
DRE, % 99.99948 99.99981 99.99974
Test 5: Low feedrate baseline
Scrubber exit flue gas
Concentration, /tg/dscm 22 4.6 1.9
Emission rate, mg/hr 32 6.7 2.8
Feedrate, kg/hr
Solid feed 1.58 0.28 0.28
Liquid feed 2.69 0.46 0.46
Total feed 4.27 0.74 0.74
DRE, % 99.99925 99.99909 99.99962
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comparably low in Test 4a. Flue gas POHC concentrations for all three POHC in the other high
CO test, Test 4b, were comparable to those measured in the baseline test, Test la.
Corresponding DREs as measured at the scrubber exit ranged from 99.9982% to 99.99977%
for toluene, from 99.9986% to 99.99981% for tetrachloroethene, and 99.9989% to 99.99981% for
chlorobenzene. Again, the lowest DREs for all three POHCs occurred in the repeat baseline test
(lb). The highest DREs for all three POHCs occurred in the high CO, reduced air flow test (4a).
POHC DREs for the high CO, increased charge mass test (4b) were comparable to, though
uniformly greater than, those measured in Test la, the baseline test.
The data in Table 1 clearly show that repeatedly exceeding an instantaneous 100 ppm CO
limit at the exit of the APCS via the two mechanisms tested did not cause increased POHC flue
gas concentrations or emission rates, nor decreased POHC DRE.
No POHC was detected in any test kiln ash or scrubber liquor sample.
Trace Metal Analysis Results
Table II summarizes the trace metal concentrations in each test program sample analyzed.
The data in the table show that measurable concentrations of barium, cadmium, chromium, and
lead were found in each of the pretest scrubber liquor samples. Arsenic was not detected in any
pretest scrubber liquor sample. Each of the test metals was found in each of the kiln ash, posttest
scrubber liquor, and flue gas samples as well. The data in Table II also show no significant test-to-
test variations in scrubber exit flue gas metal concentrations for any of the test metals. Thus, within
the concentration variability range of the duplicate baseline test metals, it appears that none of the
tested WFCO operating modes significantly affected the concentration of metals in the scrubber
exit flue gas. Similarly, metals emissions rates were apparently not significantly different for the
WFCO tests when compared with the baseline tests.
Table III summarizes the test metal distributions among the three incineration system
discharges: the kiln ash, scrubber liquor, and scrubber exit flue gas. The distribution fractions in
Table III have been normalized to the total amount of each metal measured in all the discharge
streams analyzed. Thus, these normalized values represent fractions that would have resulted had
mass balance closure in each case been 100%. Use of the distribution fractions normalized in this
manner allows clearer data interpretation for variations caused by test variables, because variable
mass balance closure is removed as a source of test-to-test data variability. In other words, because
variable and less than perfect mass balance closure is typically experienced, the use of normalized
distributions represents a best attempt to quantify metal partitioning phenomena. Actual achieved
mass balance closures ranged from 35% to 146% and averaged 62%. These levels are in the range
typically achieved at the IRF.
The data in Table III show that barium and chromium were relatively nonvolatile in all of
the tests. Greater than 98% of the barium in the discharges and 96% of the chromium in the
discharges was accounted for by the kiln ash. Less than 1% of the barium and chromium was
measured in the scrubber exit flue gas, with about 1% of the barium and 1% to 2% of the
chromium measured in the scrubber liquor. Arsenic and lead were more volatile in the tests,
though still predominantly nonvolatile Nominally 80% to 90% of the arsenic was measured in the
kiln ash discharge for all tests except the low feedrate baseline test, where it was 65% to 72% for
no readily apparent reason. Between 3% and 14% of the arsenic was measured in the scrubber
exit flue gas for all tests. Comparable, to slightly larger, fractions of arsenic were measured in the
scrubber liquor. Nominally 80% to 95% of the lead was measured in the kiln ash discharge for all
tests. About 3% to 10% of the lead was measured in the scrubber exit flue gas, and 1% to 12%
in the scrubber liquor. Cadmium exhibited even more volatile behavior than arsenic and lead in
all tests. Nominally 20% to 66% of the cadmium was accounted for in the kiln ash discharge.
Comparable amounts, 20% to 70%, were accounted for in the scrubber exit flue gas. Only 13%
or less of the cadmium was accounted for in the scrubber liquor.
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Table II. Trace metal analysis results.
Sample
Arsenic2
Barium
Cadmium
Chromium
Lead8
Test la (6/4/92), Baseline
Solid waste feed, mg/kg
29
454
15
215
77
Kiln ash, mg/kg
24
465
1.7
330
76
Afterburner exit flue gas, ^g/dscm
52-62
20
190
240
90-98
Scrubber exit flue gas, ^g/dsem
14-32
4
115
18
155-170
Pretest scrubber Liquor, mg/L
<0.05
0.28
0.03
0.07
0.43
Posttest scrubber liquor, mg/L
0.20
0.47
0.14
1.0
0.29
Test lb (6/19/92), Repeat baseline
Solid waste feed, mg/kg
29
503
16
250
106
Kiln ash, mg/kg
21
498
11
373
103
Afterburner exit flue gas, /ig/dscm
69-79
30
210
215
86-94
Scrubber exit flue gas, ^g/dscm
12-31
9
63
13-17
160
Pretest scrubber liquor, mg/L
<0.05
0.22
0.05
0.11
0.26
Posttest scrubber Liquor, mg/L
0.53
1.3
0.53
1.1
2.7
Test 2 (6/9/92), Scrubber fan failure
Solid waste feed, mg/kg
36
433
16
192
91
Kiln ash, mg/kg
26
503
10
603
107
Afterburner exit flue gas, jug/dscm
43-52
17
97
120
56-64
Scrubber exit flue gas, /xg/dscm
8-25
6
56
14
41-54
Pretest scrubber liquor, mg/L
<0.05
0.19
0.03
0.07
0.10
Posttest scrubber liquor, mg/L
0.29
0.71
0.16
0.82
0.54
Test 3 (6/11/92), Scrubber liquor flow failure
Solid waste feed, mg/kg
37
479
17
380
98
Kiln ash, mg/kg
24
503
10
340
104
Afterburner exit flue gas, /ig/dscm
64-73
58
130
140
58-79
Scrubber exit flue gas, ptg/dscm
6-28
9
42
14-17
18-36
Pretest scrubber Liquor, mg/L
<0.05
0.14
0.02
0.03
0.14
Posttest scrubber liquor, mg/L
0.16
0.36
0.07
0.26
0.17
Test 4a (6/23/92), High CO, reduced air flow
Solid waste feed, mg/kg
24
408
12.5
207
59
Kiln ash, mg/kg
20
510
1.7
225
67
Afterburner exit flue gas, /xg/dscm
175-185
30
47
190
145-155
Scrubber exit flue gas, /xg/dscm
23-34
10
130
18
40-67
Pretest scrubber liquor, mg/L
<0.05
0.23
0.04
0.12
0.19
Posttest scrubber liquor, mg/L
0.21
0.26
0.10
0.25
0.15
Test 4b (4/29/92), High CO, increased charge mass
Solid waste feed, mg/kg
33
515
16
192
76
Kiln ash, mg/kg
35
783
10
524
111
Afterburner exit flue gas, jtg/dsem
140-150
75
240
620
420
Scrubber exit flue gas, /xg/dscm
21-38
18
96
37
94-110
Pretest scrubber liquor, mg/L
<0.10
0.21
0.03
0.03
0.49
Posttest scrubber liquor, mg/L
0.21
0.63
0,21
0.79
1.5
Test 5 (6/25/92), Low feedrate baseline
Solid waste feed, mg/kg
31
450
15
330
110
Kiln ash, mg/kg
18
510
12
400
100
Afterburner exit flue gas, /zg/dscm
61-71
12
96
41
52-60
Scrubber exit flue gas, jig/dsem
8-28
9
53
16
17-33
Pretest scrubber liquor, mg/L
<0.05
0.22
0.02
0.05
0.14
Posttest scrubber liquor, mg/L
0.26
0.44
0.12
0.42
0.32
aFlue gas ranees arise when a metal'is detected in onlv one of the two sampling train samples
analyzed. The lower level in the ranse assumes nondetects present at zero concentration, the upper
level assumes nondetects present at fhe detection limit.
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Table III. Normalized trace metal distributions.
Distribution, % of metal measured
Arsenic Barium Cadmium Chromium Lead
Test la (6/4/92), Baseline
Kiln ash
87-91
99.5
19
97.4
88-90
Scrubber exit flue gas
3-7
0.1
71
0.3
10-11
Scrubber liquor
6
0.4
10
2.3
<1
Total
100
100
100
100
100
Test lb (6/19/92), Repeat baseline
Kiln ash
84-88
99.0
66
98.6
84
Scrubber exit flue gas
3-7
0.1
22
0.3
8
Scrubber liquor
9
0.9
12
1.1
8
Total
100
100
100
100
100
Test 2 (6/9/92), Scrubber fan failure
Kiln ash
79-85
98.4
54
98.1
90
Scrubber exit flue gas
3-10
0.2
37
0.3
5
Scrubber liquor
11-12
1.4
9
1.6
5
Total
100
100
100
100
100
Test 3 (6/11/92), Scrubber liquor flow failure
Kiln ash
77-85
98.8
60
98.0
95-97
Scrubber exit flue gas
3-13
0,2
34
0.6
2-4
Scrubber liquor
10-12
1.0
6
1.4
1
Total
100
100
100
100
100
Test 4a (6/23/92), High CO, reduced air flow
Kiln ash
81-83
99.7
18
98.6
94-97
Scrubber exit flue gas
5-7
0.1
71
0.4
3-5
Scrubber liquor
12
0.2
11
1.0
<1
Total
100
100
100
100
100
"est 4b (4/29/92), High CO, increased charge mass
Kiln ash
82-86
98.8
43
97.0
80-81
Scrubber exit flue gas
6-10
0.3
44
0.7
7-8
Scrubber liquor
8
0.9
13
2.3
12
Total
100
100
100
100
100
"est 5 (6/25/92), Low feedrate baseline
Kiln ash
65-72
98.7
56
97.4
92-94
Scrubber exit flue gas
5-14
0.3
34
0.5
2-4
Scrubber liquor
21-23
1.0
10
2.1
4
Total
100
100
100
100
100
The data in Table III show no repeatedly significant difference in metals distributions from
test to test for any of the metals, within the degree of data variability exhibited in the two baseline
tests, within the precision of the measurements, or both. This suggests that metals partitioning
among the incinerator discharges was relatively unaffected by the different tested operating
conditions leading to repeated WFCOs,
Table IV summarizes the apparent scrubber collection efficiencies for the metals. Apparent
scrubber collection efficiencies are calculated by assuming that the sum of the amount of metal
measured in the two scrubber discharges (the scrubber liquor and the scrubber exit flue gas) was
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Table IV. Apparent scrubber trace metal collection efficiencies.
Apparent scrubber collection
efficiency,8 %
As Ba Cd Cr Pb
Test la (6/4/92), Baseline
Test lb (6/19/92), Repeat baseline
Test 2 (6/9/92), Scrubber fan failure
Test 3 (6/11/92), Scrubber liquor flow failure
Test 4a (6/23/92), High CO, reduced air flow
Test 4b (4/29/92), High CO, increased charge mass
Test 5 (6/25/92), Low feedrate baseline
48-68 88 13 89 <3
54-76 89 35 80-84 51
54-79 90 20 85 46-54
46-81 80 16 67-71 15-26
64-73 69 14 72 < 15
45-60 78 22 76 59-63
61-84 81 23 79 49-65
a(Scrubber liquor fraction)/(scrubber liquor fraction + scrubber exit flue gas fraction),
the amount of metal in the scrubber inlet flue gas. Thus, apparent scrubber collection efficiency
is calculated as (scrubber liquor fraction)/(scrubber liquor fraction + scrubber exit flue gas
fraction).
Data in Table IV show that the venturi/packed column scrubber system was nominally 70%
to 90% efficient in collecting barium and chromium. Arsenic apparent collection efficiencies were
perhaps as low as 45% to 64% Cadmium apparent collection efficiencies were lower, in the
13% to 35% range. Lead apparent collection efficiencies were highly variable. Within the range
of variability in the data, however, no test-to-test differences in collection efficiencies are apparent.
This suggest that none of the repeated WFCOs tested affected scrubber metals collection
efficiencies.
Particulate and HC1 Emission Data
Table V summarizes the particulate levels measured at the afterburner exit (scrubber inlet)
and scrubber exit. The data in the table show that afterburner exit particulate levels ranged from
48 to 98 mg/dscm, corrected to 7% 02, for the two baseline, the two scrubber failure, and the low
feedrate baseline tests, Tests la, lb, 2,3, and 5. Afterburner exit particulate levels were apparently
increased, ranging from 133 to 148 mg/dscm, for the two high CO WFCO tests. This is probably
because of a combination of increased kiln ash entrainment into the combustion gas, as well as
some flue gas soot formed during the high CO tests. Significant soot formation was evident during
both high CO tests in visual observations of the kiln combustion gas and the substantial darkening
of the scrubber liquor with collected soot.
Scrubber exit particulate levels were reduced to the 8 to 15 mg/dscm at 7% 02 for Tests la,
lb, 2, 3, and 5. Scrubber exit particulate levels were essentially the same for the two scrubber
failure tests as for the two baseline and the low feedrate baseline tests. Thus, the two scrubber
failure modes tested with WFCO resulted in no apparent increased particulate emissions.
Scrubber exit particulate emissions for the two high CO WFCO tests were slightly higher,
at 17 and 26 mg/dscm at 7% 02. These are probably because of the higher scrubber inlet loadings
for the two tests. Table 5 also notes the particulate removal efficiencies of the scrubber system,
calculated based on the scrubber inlet (afterburner exit) and exit levels measured. Removal
efficiencies were not significantly different from test to test, ranging from 11% to 89%.
Table VI summarizes the 11 CI levels measured in the flue gas at the three locations sampled.
As shown in the table, afterburner exit HC1 levels ranged from 325 to 1.130 ppm with the test-to-
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Table V, Flue gas particulate levels.
Flue gas particulate,
mg/dscm at 7% P2 Scrubber
Afterburner
Scrubber
removal
Test
Date
exit
exit
efficiency, %
la:
Baseline
6/4/92
98
15
85
lb:
Repeat baseline
6/19/92
52
12
77
2:
Scrubber fan failure
6/9/92
81
10
88
3:
Scrubber liquor flow failure
6/11/92
67
9
87
4a:
High CO, reduced airflow
6/23/92
148
17
89
4b:
High CO, increased charge mass 4/29/92
133
26
80
5:
Low feedrate baseline
6/25/92
48
8
83
Table VI. Flue gas HCI levels.
Afterburner exit Scrubber exit
HCI
concentration,
HCI
emission
HCI
concentration,
HCI
emission
Scrubber
Test
mg/dscm
ppm
rate,
g/hr
mg/dscm
ppm
rate,
g/hr
efficiency,
%
Test la (6/4/92), Baseline
1,100
724
1,980
1.6
1.1
3.4
99.8
Test lb (6/19/92), Repeat
baseline
1,090
718
1,950
2.2
1.4
4.2
99.8
Test 2 (6/9/92), Scrubber fan
failure
545
359
990
0.8
0.5
1.3
99.9
Test 3 (6/11/92), Scrubber
liquor flow failure
494
325
916
0.9
0.6
1.7
99.8
Test 4a (6/23/92), High CO,
reduced airflow
1,640
1,080
2,250
2.3
1.5
2.9
99.9
Test 4b (4/29/92), High CO,
increased charge mass
1,710
1,130
2,850
2.4
1.6
4.5
99.8
Test 5 (6/25/92), Low feedrate
baseline
638
420
1,110
1.2
0.8
1.8
99.8
test variations in chlorine feedrate as determined by waste feedrate and chlorine content. Scrubber
exit HCI levels were reduced to 0.5 to 1.6 ppm. Relatively constant scrubber HCI collection
efficiencies, at 99.8% to 99.9%, were measured. The two scrubber failure modes tested, with
attendant WFCO, apparently did not result in increased HCI emissions or decreased scrubber HCI
collection efficiency.
CONCLUSIONS
Test program results show that none of the incinerator operating modes tested, which
resulted in repeated WFCOs. caused increased hazardous constituent or HCI emissions. The DREs
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for the three test POHCs (toluene, tetrachloroethene, and chlorobenzene) ranged from 99.9982%
to 99.99981% over the test program. The lowest DREs were measured in one of the two baseline
tests (Test lb). The highest DREs were measured in the repeated CO spike test in which CO
spikes were produced by reducing the combustion air flowrate to the incinerator from the baseline
test levels. The other CO spike test, in which CO spikes were produced by increasing the mass and
heat content of each batch charge of solid waste to an overcharge situation, had POHC DREs
comparable to the other baseline test (Test la). POHC DREs for the two scrubber system failure
tests, one in which venturi scrubber pressure drop was repeatedly reduced by shutting off the
scrubber induced draft fan (fan failure) and the other in which scrubber liquor flow was stopped
by shutting off the scrubber system recirculation pump, were also comparable to those measured
in the baseline tests.
Within the variability in the test-to-test trace metal data, none of the repeated WFCO
operating modes tested resulted in increased flue gas metals emissions. Scrubber exit flue gas
concentrations and emissions rates of arsenic, barium, cadmium, chromium, and lead for the two
scrubber failure and two high CO WFCO tests were not significantly different than those for the
baseline tests. Trace metal distributions among the three incinerator discharge streams (kiln ash,
scrubber liquor, and scrubber exit flue gas) and scrubber trace metal collection efficiencies were
not significantly different from baseline to WFCO tests, again within the test-to-test data variability
and the precision of the metals analysis methods.
Flue gas HQ concentrations and emission rates at the scrubber exit varied only with the
feedrate of chlorine in the wastes fed to the incinerator. Scrubber HC1 collection efficiencies were
99.8% to 99.9% for all tests and were not reduced with any scrubber failure or high CO operating
mode tested.
Flue gas particulate levels at the scrubber exit were in the 8 to 15 mg/dscm at 7% 02 range
for all tests except the two high CO WFCO tests. Flue gas particulate levels at the scrubber exit
for the two scrubber failure WFCO tests were lower than levels measured in the two baseline tests.
Scrubber exit particulate levels were higher, at 17 and 26 mg/dscm, for the two high CO WFCO
tests. These, however, were the result of increased scrubber inlet particulate levels for these two
tests. Scrubber particulate collection efficiency was relatively constant at llc'c to 89% from test
to test.
The higher inlet particulate levels for the high CO WFCO tests probably resulted from a
combination of increased entrainment of solids from the kiln into the kiln exit combustion gas and
soot formed during the incomplete combustion environment resulting in the CO spikes. The
increased entrainment results from the high intensity puff of incompletely combusted organics
associated with kiln overcharging used to produce the high CO.
Overall, test results suggest that the permit requirement to terminate waste feed whenever
a permit-specified operating limit is exceeded is an appropriate protection against increased
incinerator emissions of POHCs, trace metals, and HC1. Only particulate emissions increases (of
perhaps double the baseline, routine operation levels) were measured in these tests. Further, these
increases were not associated with APCS failures but with increased APCS inlet particulate levels
arising from combustion conditions associated with repeated CO spikes.
Barium and chromium exhibited nonvolatile behavior in all the tests performed. Greater
than 98% of the barium and 96% of the chromium measured in incinerator discharges was
accounted for in the kiln ash. Arsenic and lead exhibited more volatile behavior. The kiln ash
discharge accounted for 80% to 90% of the arsenic measured in the discharges for all tests except
the low feedrate baseline test, Test 5 which was 65% to 72%. Nominally 80% to 95% of the lead
measured in the incinerator discharges was in the kiln ash. Cadmium was even more volatile in
all tests; 18% to 66% of the cadmium in the discharges was accounted for in the kiln ash. These
observations are consistent with past IRF metal partitioning experience.
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NOTICE
The information described in this paper has been funded wholly or in part by the U.S.
Environmental Protection Agency under Contract 68-C9-0038 to Acurex Environmental
Corporation, It has been subjected to the Agency's peer and administrative review and approved
for presentation and publication.
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TECHNICAL REPORT DATA
tPlease read Instructions on the reverse before complain
1. REPORT NO. j 2.
EPA/600/A-93/257 \
3. Rl
4. TITLE AND SUBTITLE
Evaluation of the Impacts of Incinerator
Waste Feed Cutoffs
5. REPORT OATE
6. PERFORMING ORGANIZATION CODE
7, AUTHOR(S)
Larry R. Waterland and W. Eddie Whitworth, Jr.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Acurex Environmental
Incineration Research Facility
Jefferson, Arkansas 72079
io. program element no.
11, CONTRACT/GRANT NO.
Contract No. 68-C9-0038
12. SPONSORING AGENCY NAME AND ADDRESS
Risk Reduction Engineering Laboratory--Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Conference Proceedinas
14. SPONSORING AGENCY CODE
EPA/600/14
is. supplementary notes presented at the AWMA International Specialty Conference
Robert C. Thurnau, Project Officer 513/569-7504
16. ABSTRACT
A series of pilot-scale incineration tests was performed at the EPA's Incineration Research Facility
(IRF) to-evaluate whether increased emissions of regulated pollutants could occur when an incinerator's
automatic waste feed cutoff (WFCO) system repeatedly stops waste feed to the incinerator. Seven tests
were performed in the rotary kiln incineration system with at the IRF. These included duplicate baseline
tests simulating acceptable operation, two tests with WFCOs triggered by scrubber system failures, two tests
with scrubber exit CO spikes of several hundred ppm, and a baseline test with reduced waste feedrate.
Test program results show that none of the tested incinerator operating modes caused significant
increased POHC, trace metal, or HC1 emissions. POHC destruction and removal efficiencies (DREs) for
all repeated WFCO tests were within the range measured for the two baseline tests. Similarly, trace metal
emission rates and distributions among incinerator discharges for all repeated WFCO tests could not be
differentiated from the baseline tests. Scrubber HC1 collection efficiencies were constant, at 99.8% to
99.9% for all tests. Scrubber exit particulate levels in the scrubber failure tests were no greater than in the
baseline tests. However, they were increased to as much as double the baseline test levels in the high-CO
tests because of increased scrubber inlet particulate at constant collection efficiency. Overall, test results
suggest that the permit requirement to terminate waste feed whenever a permit-specified operating limit
is exceeded apparently prevents significantly increased incinerator emissions of POHCs, trace metals, and
HQ; particulate emissions can increase, however.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATl Field/Group
Incinerators
Hazardous Materials
Emissions
Metals
Organic Compounds
Waste Feed Cutoff
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS /This Report)
UNCLASSIFIED
21. NO. OF PAGES
14
20. SECURITY CLASS iTIus p
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