United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-97/061 September 1997
Burner Technology
S. Venkatesh, W. E, Whitworth, Jr., C. Goldman, and L. R, Water-land
A series of demonstration tests was
performed at the Environmental Pro-
tection Agency's (EPA's) Incineration
Research Facility (IRF) under the Su-
perfund Innovative Technology Evalua-
tion (SITE) program. These tests, 12 in
all, evaluated a pulse combustion
burner technology developed by
Sonotech, Inc., of Atlanta, Georgia. The
burner system incorporates a pulse
combustor, the pulsation frequency of
which can be tuned to induce large
amplitude sonic pulsations inside a
combustion process unit such as a
boiler or an incinerator.
The primary objective of the test pro-
gram was to develop test data to allow
evaluating whether the Sonotech pulse
combustor applied to the IRF rotary
kiln system (RKS), when compared to
conventional, non-pulsating combus-
tion, resulted in: decreased flue gas
NOX, CO, and soot emissions; increased
POHC ORE; decreased combustion air
requirements; decreased auxiliary fuel
requirements; and increased incinera-
tor capacity. The waste feed for all tests
was a mixture of contaminated materi-
als from two manufactured gas plant
(MGP) Superfund sites. One component
of the test waste was a combination of
pulverized coal and contaminated
sludge waste from the Peoples Natural
Gas Company site in Dubuque, Iowa.
The other components of the waste
consisted of soil borings and a tar
waste from an oil gasification process
obtained from an MGP site in the south-
east U.S. To address the demonstra-
tion objectives 12 tests were performed
under four different test conditions.
Each condition consisted of three iden-
tical to obtain data in triplicate.
Test data were statistically evaluated
using the rank sum test. When the rank
sum test is applied to two data sets,
each containing three points, the
data are different, at the 95 per-
cent confidence level, when corre-
sponding ranges do not overlap.
The results addressing the primary
objectives of the program are
as follows: the average CO emissions
at the afterburner exit decreased from
20 ppm (range of 8.0 to 40.0 ppm) for
test condition 2 to 14 ppm (range of
12.6 to 16.0 ppm) for test condition 3;
the average NOX decreased from 82 ppm
(range of 78.3 to 85.1 ppm) for test con-
dition 2 to 77 ppm (range of 68.0 to
87.1 ppm) for test condition 3; the av-
erage soot emissions decreased from
1.9 mg/dscm (range of 0.9 to 2.7 mg/
dscm) to than 1.0 mg/dscm (range
of <0.8 to 0.9 mg/dscm). Benzene ORE
for all 12 tests was greater than 99.994
percent. Naphthalene ORE for all 12
tests was greater than 99.998 percent.
The combustion air requirements
showed a decrease from the 38,400 to
40,600 dscfh range to the 34,800 to
39,900 dscfh range when the Sonotech
combustor was used; the auxiliary fuel
requirements (natural gas) were practi-
cally equal under conventional and
Sonotech conditions; and the waste
feedrate capacity increased by 13 per-
cent with the Sonotech burner opera-
tional. As the demonstration waste had
a significant heat content (8,500 Btu/
Ib), the capacity increase may be trans-
lated into a reduction in auxiliary fuel
needed to treat a unit mass of waste
from 21.1 kBtu/lb for conventional com-
bustion to 18.0 kBtu/lb for the Sonotech
system.
This Project Summary was developed
by EPA's National Risk Management
Research Laboratory, Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
-------
Project Report ordering information at
back),
Introduction
Sonotech, Inc., of Atlanta, Georgia, has
developed a pulse combustion burner tech-
nology that claims to offer benefits when
applied in a variety of combustion pro-
cesses. The burner system incorporates a
pulse combustor that can be tuned to ex-
cite large-amplitude sonic pulsations in-
side a combustion chamber such as a
boiler or incinerator. Sonotech claims that
these pulsations serve to increase the
rates of heat, mixing (momentum), and
mass transfer in the combustion process;
and claims that these rate increases are
sufficient to result in more complete com-
bustion.
Sonotech has targeted waste incinera-
tion as a potential application for this tech-
nology. Accordingly, to demonstrate the
claimed benefits of the technology within
a well-established forum for providing tech-
nically sound and unbiased evaluations,
Sonotech proposed a technology evalua-
tion test series under the Superfund Inno-
vative Technology Evaluation (SITE)
program. The Sonotech proposal was ac-
cepted, and an evaluation test program
was performed at EPA Incineration Re-
search Facility (IRF) in Jefferson, Arkan-
sas.
Description of the Technology
A pulse combustor typically consists of
an air inlet, a combustor section, and a
tailpipe. Periodic variations in fuel oxida-
tion and heat release produce pulsations
in the combustor section pressure, tem-
perature, and gas velocities. When prop-
erly applied, a pulse combustor can excite
large-amplitude (150 dB or greater) pulsa-
tions within a cavity downstream of the
pulse combustor tailpipe. This cavity could
be the combustion chamber of a boiler or
an incinerator, for example.
A retrofit application of the Sonotech
pulse combustion system was evaluated
in this test program. Specifically, the kiln
section of the RKS at the IRF was retrofit-
ted with a pulse combustion burner ca-
pable of delivering up to 73 kW
(250,000 Btu/hr) of heat input from natural
gas fuel to the kiln. This corresponds to
15 to 20 percent of the typical heat input
to the kiln. The RKS was configured as
shown in Figure 1, with the Sonotech com-
bustion system retrofitted into the end plate
at the ash discharge end of the kiln.
Demonstration Objectives
Sonotech claims that the application of
pulse combustion technology to an incin-
eration system has several significant ad-
vantages over conventional (non-pulsating)
incineration. Thus, the general objective
of the demonstration test program was to
develop the data needed to allow objec-
tive and quantitative evaluation of these
claims. Accordingly, the primary test pro-
gram objective was to develop test data
to allow evaluating whether the Sonotech
pulse combustion technology applied to
the IRF RKS, when compared to conven-
tional, non-pulsating combustion, resulted
in:
Increased incinerator capacity or
productivity
Increased principal organic hazard-
ous constituent (POHC) destruction
and removal efficiency (ORE)
Decreased flue gas CO emissions
Decreased flue gas NOX emissions
Decreased flue gas soot emissions
Decreased combustion air require-
ments
Decreased auxiliary fuel require-
ments
The secondary test program objective
was to develop test data to allow evaluat-
ing whether the application of the Sonotech
technology, when compared to conven-
tional, non-pulsating combustion:
Reduced the magnitude of transient
puffs of CO and total unburned hy-
drocarbons (TUHC)
Allowed reduced incineration costs
Caused significant changes in:
Quench
Y
Secondary
burner „„ ,
H-i Afterburner
Air extension
Natural 1
gas, y | ooiius
liquid Ll Afterburner Bed
feed II — 1 Feeder
Transfer fl 1 I
duct — * \ T-II H-I-I LJ .
1 1 1=0 ^ain
Natural . — __;, I I K^ burner
yd& Ar psh iMJip J
Sonotech 0 '»
Burner ^°tary Natural
system Klm gas
liquid feed
Rotary Kiln Incinerator
^te
tx Pac
/\ Co1
f \ Scr
— "jam '}
Venturi T \/
scrubber ^
Scrubber
Iquor
recirculation
K/1 '
] ID fan
{>< reheater
' \
MM
\ /
Ash hopper | |
Primary Air Pollution Control System
^\7y^
'• ^^ ^' KN
Carbon bed HEPA
adsorber filter
ghouse
Secondary Air Pollution
Control System
Atmosphere
t
n Stack
X
K^O
> (UJ
ID fan
Figure 1. Schematic of the IRF rotary kiln incineration system.
-------
— The distribution of hazardous
constituent trace metals among
the incineration system dis-
charge streams (kiln bottom
ash, scrubber liquor, baghouse
flyash, and baghouse exit flue
gas)
— The leachability of the toxicity
characteristic leaching proce-
dure (TCLP) trace metals from
kiln bottom ash, scrubber liquor,
and baghouse flyash
This last secondary objective item does
not relate to any Sonotech claim, but is of
general interest to the overall IRF research
program.
Test Program
To address the test program objectives,
tests at the following four different incin-
eration system operating conditions were
performed:
Test Condition 1: Conventional
combustion under baseline, typical
RKS operation (28 kg/hr [61 Ib/hr])
Test Condition 2: Conventional
combustion at the maximum RKS
waste feedrate without pulsations
(33 kg/hr [73 Ib/hr])
Test Condition 3: Sonotech pulse
combustion at nominally the same
feedrate and conditions as Test
Condition 2 (34 kg/hr [74 Ib/hr])
Test Condition 4: Sonotech pulse
combustion at the maximum RKS
waste feedrate with pulsations (37
kg/hr [82 Ib/hr])
The test waste feed for all tests was a
mixture of contaminated materials from
two manufactured gas plant (MGP) Su-
perfund sites. (The specific components
of this feed are discussed later.) This waste
feed was batch fed to the RKS via the
system's fiberboard container ram feed
system, which feeds 1.5-gal (5.7-L) fiber-
board containers to the kiln at virtually
any specified feed frequency. When a rela-
tively high heat content material is being
fed, the maximum allowable waste feedrate
is established based upon the onset of
puffs of incompletely combusted organic
constituents (CO and TUHC) that survive
the afterburner.
Given this, Test Condition 1 was at a
waste feedrate consistent with stable in-
cinerator operation under conventional
combustion, with infrequent spikes of CO
and/or TUHC at the afterburner exit. Test
Condition 2 was at an increased waste
feedrate that resulted in routine afterburner
CO spikes. This condition could be termed
borderline acceptable incinerator opera-
tion under conventional combustion. Test
Condition 3 was at the same waste
feedrate as Test Condition 2, but with the
Sonotech pulse combustion system in op-
eration. Test Condition 4 was at a further
increase in waste feedrate, with the pulse
combustor in operation, such that routine
afterburner exit flue gas CO spikes re-
curred. This condition could be termed
borderline acceptable operation under
pulse combustion operation. Three test
runs (triplicate testing) at each test condi-
tion were completed to allow the precision
of each emission and discharge stream
composition measurement to be assessed.
As indicated above, the test waste feed
material for the test program was a mix-
ture of materials from two MGP Super-
fund sites. One component of the material
was a combination of pulverized coal and
contaminated sludge/soil waste from the
Peoples Natural Gas Company Superfund
site in Dubuque, Iowa. This site is an
abandoned coal MGP site, and the sludge
waste at the site contains high concentra-
tions of coal tar constituents. The other
components of the test feed material were
contaminated soil borings and a tar waste
from an oil gasification process, both ob-
tained from an MGP site in the southeast-
ern United States.
The hazardous constituent contaminants
of all three test waste components were
several polynuclear aromatic hydrocarbon
(PAH) compounds, and the VOCs ben-
zene, toluene, ethylbenzene, and xylenes
(BTEX). Although concentrations of sev-
eral contaminant compounds were quite
high in at least the tar component of the
waste mixture, it was decided that spiking
the waste feed with benzene and naph-
thalene would be necessary to guarantee
meaningful ORE calculations.
To address the test program objectives,
the composite waste feed, the kiln ash
discharge, the scrubber system liquor, the
collected baghouse ash, the afterburner
exit flue gas particulate, the afterburner
exit flue gas, and the baghouse exit flue
gas for each test were sampled and ana-
lyzed for sample-matrix-specific combina-
tions of PAHs, VOCs, contaminant trace
metals, polychlorinated dibenzo-p-dioxins
and polychlorinated dibenzofurans
(PCDDs/PCDFs), and TCLP-leachable
trace metals. In addition, the total organic
carbon (TOC) content of the afterburner
exit flue gas particulate was determined
and used as the measure of soot emis-
sions. Later in the test program, measur-
ing the heating value of each test's kiln
ash discharge was added as an indication
of waste treatment residue quality in terms
of completeness of waste burnout.
Test data from the program were evalu-
ated using the rank sum test. The rank
sum test says the two data sets, each
containing three data points (the case for
this program) are statistically different at
the 95 percent confidence level when the
data ranges in each set do not overlap.
Test
Incinerator Operating
Conditions
Table 1 provides a summary of the av-
erage incineration system operating con-
ditions for each of the four program test
conditions. Each operating parameter
noted in the table was recorded nominally
every 30 seconds over a 4- to 5-hour flue
gas sampling period for each test by the
RKS data acquisition system. Test aver-
ages were calculated for each parameter.
The data in Table 1 represent the aver-
age value determined for the three tests
performed for each test condition.
The data in Table 1 show that the kiln
exit gas temperatures collected for all con-
ditions averaged close to the test program
target of 925°C (1,700°F), and that aver-
age afterburner exit gas temperatures were
right at the test program target of 1,095°C
(2,000°F). Afterburner exit flue gas O2 lev-
els averaged close to 9 percent for all test
conditions, although slightly lower aver-
age levels existed for Test Conditions 3
and 4, the two pulse combustion test con-
ditions.
The baseline (Test Condition 1) waste
feedrate was 27.7 kg/hr (61.0 Ib/hr). This
feedrate was increased to 33.1 kg/hr
(72.8 Ib/hr) to give the borderline accept-
able operation associated with Test Con-
dition 2. Test Condition 3, with the pulse
combustion system in operation, was per-
formed at nominally the same (just slightly
higher) feedrate as Test Condition 2, as
planned. The Test Condition 3 feedrate
was 21 percent greater than the Test Con-
dition 1 feedrate. A further 13-percent
feedrate increase over that for Test Con-
dition 2 was possible before incinerator
operation entered the borderline accept-
able regime with the pulse combustion
system in operation. Thus, with respect to
the Sonotech claim that increased incin-
erator capacity can be realized with pulse
combustion, test data show that a capac-
ity increase in the range of 13 percent
(comparing Test Condition 4 to Test Con-
dition 2) can indeed be realized.
The data in Table 1 further show that
the total system heat input needed to main-
tain target incineration temperatures was
relatively constant for all four test condi-
tions at about 645 kW (2.2 MBtu/hr). Spe-
cifically comparing the auxiliary fuel use
for Test Condition 3 to that for Test Con-
dition 2 shows that the auxiliary fuel re-
quirements were nominally the same.
-------
Table 1. Test Condition Operating Data
Test condition average (3 tests)
Parameter
Waste feedrate, kg/hr (Ib/hr)
1
Conventional
baseline
27.7 (61.0)
2
Conventional
max. feed
33.1 (72.8)
3
Pulsations
feed as in 2
33.5 (73.6)
4
Pulsations
max. feed
37.5 (82.4)
Kiln
Gas temperature, °C (°F) 935 (1,720)
Solids bed temperature, °C (°F) 965 (1,770)
Afterburner exit gas temperature, 1,095 (2,000)
°C (°F)
940 (1,730)
990 (1,810)
1,095 (2,000)
925 (1,700)
1,020 (1,870)
1,095 (2,000)
925 (1,700)
1,030 (1,890)
1,095 (2,000)
Afterburner exit O2, %
Heat input, kW (kBtu/hr)
Waste feed
Kiln auxiliary fuel
Main burner
Sonotech burner
Total kiln
Afterburner auxiliary fuel
Total auxiliary fuel
Total system heat input, kW (kBtu/hr)
Auxiliary fuel consumption per unit of
waste treated, MJ/kg (Btu/lb)
9.3
153 (522)
193 (659)
0 (0)
193 (659)
297 (1,012)
489 (1,668)
642 (2,190)
63.6 (27,400)
9.3
176 (601)
148 (506)
0 (0)
148 (506)
303 (1,035)
454 (1,551)
630 (2,152)
49.2 (21,100)
8.7
184 (628)
82 (282)
59 (200)
141 (482)
321 (1,094)
462 (1,576)
646 (2,204)
49.7 (21,400)
8.5
204 (697)
60 (205)
59 (200)
119 (405)
317 (1,082)
436 (1,487)
640 (2,184)
41.8 (18,000)
Thus, the Sonotech claim that decreased
auxiliary fuel use would be possible with
the application of pulse combustion is not
supported by the test data. However, be-
cause the waste treated in these tests
had significant heat content, the capacity
increase noted above equates to a corre-
sponding decrease in the auxiliary fuel
consumed per unit of waste treated. Com-
paring the auxiliary fuel consumption per
unit of waste treated for Test Condition 4
to that for Test Condition 2 shows that the
feedrate increase allowed by the Sonotech
system yields a corresponding decrease
in auxiliary fuel use per unit of waste
treated from 49.2 MJ/kg (21,200 Btu/lb) to
41.9 MJ/kg (18,000 Btu/lb). Visual obser-
vations suggest that the Sonotech system
produced visually improved mixing in the
kiln chamber.
With respect to combustion air require-
ments, the data in Table 1 show that less
combustion air was required, when the
same feedrate was used, for the pulse
combustion test condition compared to the
conventional combustion test condition.
POHC DREs and
Quality
The POHC DREs and emission rates at
the two flue gas locations sampled are
summarized in Table 2. As shown in the
table, naphthalene DREs measured at both
the afterburner exit and the baghouse exit
were uniformly 99.999 percent or greater
for all tests, and were not affected by the
different test conditions or different waste
feedrates. Benzene DREs measured at
the two locations were uniformly
99.994 percent or greater (one baghouse
exit benzene ORE measurement was
99.989 percent), and again not affected
by the different test conditions.
The average naphthalene emission rate
at the afterburner exit was reduced from
1.2 mg/hr (range of 0.4 to 2.6 mg/hr), for
conventional combustion at Test Condi-
tion 2, to 1.1 mg/hr (range of <0.3 to
2.5 mg/hr), with the Sonotech system at
the Test Condition 3. The average ben-
zene emission rate at the afterburner exit
was reduced from 7.7 mg/hr (range of 2.1
to 12), for Test Condition 2, to 5.7 mg/hr
(range of 3.4 to 6.9), for Test Condition 3.
However, the significance of the decreases
is also difficult to judge because both fall
within the precision of the respective flue
gas concentration measurement methods.
With respect to this, it bears noting that
benzene emissions increased from Test
Condition 2 to Test Condition 3 when mea-
sured at the baghouse exit.
The kiln ash heating value data shown
in Table 1 suggest that incineration resi-
due quality, as measured by residue (kiln
ash) heating value, was improved with
pulse combustion. A decrease in kiln ash
heating value from 3.1 MJ/kg (1,340 Btu/
Ib), for Test Condition 2, to <1.1 MJ/kg
(<500 Btu/lb), for Test Condition 3, at the
same nominal feedrate but with pulse com-
bustion, was seen. The solids bed tem-
perature data shown in the table are
consistent with this decrease. Solids bed
temperatures were measured at four axial
locations in the kiln during the tests. The
temperature at the location recording the
peak temperature for each test was aver-
aged over the flue gas sampling period
for that test. The entries in Table 1 repre-
sent the average of these individual test
averages for the three test runs at each
test condition. The data show an increase
in average peak solids bed temperature
of from 965°C (1,770°F) (Test Condition 1)
-------
Table 2. Test Program POHC ORE Summary
Benzene
Naphthalene
Afterburner exit
Condition 1
Testl
Tests
Test 10
Average
Condition 2
Test 2
Test?
Test 11
Average
Condition 3
Test3
Tests
Test9
Average
Condition 4
Test 4
Tests
Test 12
Feed-
rate
g/hr
253.1
253.1
244.1
298.3
307.3
289.2
7
289.2
307.3
307.3
7
343.5
334.4
334.4
Emission
rate,
mg/hr
44
7.6
14.8
8.9
99.99
4
99.99
6
9.0
2.1
12.0
7.7
99.99
5
99.99
6.9
3.4
6.7
5.7
99.99
7
99.99
10.4
11.7
50.9
ORE,
%
99.99
8
99.99
6
99.99
6
99.99
9
99.99
7
99.99
8
99.996
99.996
99.998
Baghouse exit
Emission
rate,
mg/hr
<1.2
2.1
3.4
2.2
31.0
<0.9
0.6
1.5
6.4
1.5
2.9
3.6
2.5
<1.S
1.1
ORE,
%
>99.999
99.999
99.998
99.999
99.989
>99.999
99.999
99.996
99.997
99.999
99.999
99.998
99.999
>99.999
99.999
Feed-
rate
g/hr
378.0
378.0
364.5
445.5
459.0
432.0
432.0
459.0
459.0
513.0
499.5
499.5
Afterburner exit
Emission
rate,
mg/hr
6.2
2.9a
<0.3
3.1
2.6a
0.6a
0.4a
1.2
2.5a
<0.3
0.5a
1.1
0.6b
0.5b
1.3"
ORE,
%
99.998
99.999
>99.999
99.999
99.999
99.999
99.999
99.999
99.999
>99.999
99.999
99.999
99.999
99.999
99.99
Baghouse exit
Emission
rate,
mg/hr
5.9
3.1a
2.5a
3.8
6.0
<0.3
3.5a
3.3
2.4a
0.6a
1.6a
1.5
1.4"
2.2b
0.4b
ORE,
%
99.998
99.999
99.999
99.999
99.999
>99.999
99.999
99.999
99.999
99.999
99.999
99.999
99.999
99.999
99.999
aAverage concentration of three pairs of M0030 VOST tubes.
bAna!yte below lowest calibrated level.
"<" = Analyte below method detection limit.
-------
to 990°C (1,810°F) (Test Condition 2), for
conventional combustion, to 1,020°C
(1,870°F) (Test Conditions) to 1,030°C
(1,890°F) (Test Condition 4), for pulse
combustion. Specifically, comparing the
data for Test Condition 3 to those for Test
Condition 2 shows an increase from 990°C
(1,810°F), for conventional combustion, to
1,020°C (1,870°F), for pulse combustion,
at the same waste feedrate and other
system operating conditions. These data
suggest that the Sonotech claim of in-
creased heat transfer rates with pulse com-
bustion, specifically to the solids bed, is
justified. An increase in heat transfer rate
to the solids bed would cause the in-
creased bed temperatures seen and the
corresponding decrease in kiln ash dis-
charge heating value.
CO, NOX, Soot
Table 3 summarizes the continuous
emissions monitor (CEM) and soot emis-
sions data for the test program. As for the
operating conditions data, summarized in
Table 1, CEM readings were recorded at
nominally 30~second intervals on the RKS
data acquisition system. These readings
were averaged over the flue gas sampling
period for each test The CEM entries in
Table 3 represent the average of each
test's average for the three tests at each
test condition.
The data in Table 3 show that average
kiln exit CO levels substantially increased
with pulse combustion, from 68 ppm at
7 percent O2 for the two conventional com-
bustion test conditions (1 and 2), to
117 ppm at 7 percent O2 for Test Condi-
tion 3 and to 153 ppm at 7 percent O2 for
Test Condition 4. This increase is consis-
tent with both the kiln solids bed tempera-
ture and the kiln ash residue quality data
in Table 1. As discussed above, pulse
combustion caused increased kiln solids
bed temperatures and decreased kiln ash
heating values, suggesting that pulse com-
bustion caused a greater degree of waste
feed organic content devolatilization into
the kiln combustion gas. The observation
that kiln exit CO levels were increased
with pulse combustion suggests that the
greater amounts of devolatilized organics
were not completely destroyed in the kiln.
Average afterburner exit CO levels were
decreased to 15 ppm at 7 percent O2
(range of 8.7 to 25.6 ppm), for Test Con-
dition 1, and to 20 ppm at 7 percent O2
(range of 8.0 to 40.0 ppm), for Test Con-
dition 2. Compared to conventional com-
bustion, pulse combustion produced
slightly lower average afterburner exit CO
levels. Comparing Test Condition 3 (pulse
combustion) to Test Condition 2 (with con-
ventional combustion), both of which had
the same waste feedrate, shows that pulse
combustion resulted in decreased aver-
age afterburner exit CO emissions of
14 ppm at 7 percent O2 (range of 12.6 to
16.0 ppm. Even at the increased waste
feedrate achieved with pulse combustion
for Test Condition 4, afterburner exit CO
levels were only marginally increased, to
17 ppm at 7 percent O2 (range of 10.5 to
26.2 ppm) — higher than the Test Condi-
tion 3 level, but still lower than the Test
Condition 2 level.
CO is the final incomplete combustion
product in the series of reactions that con-
verts the carbon in organic constituents to
CO2. Thus, an explanation for why after-
burner exit CO levels under pulse corn-
Table 3. Continuous Emissions Monitor Data
Test condition average (3 tests)
Constituent
Conventional
baseline
Conventional
max. feed
Pulsations
feed as in 2
4
Pulsations
max. feed
Kiln exit:
CO, ppm at 7% O2
Afterburner exit:
CO, ppm at 7% O2
NOX, ppm at 7% O2
Soota, mg/dscm at 7% O2
Baghouse exit:
NOt, ppm at 7% O7
68
15
90
<1.3b
68
20
82
1.9
85
117
14
77
<1.
78
153
18
78
1.3
72
'Measured as TOC in participate.
bMeasured for only one test.
bustion operation were lower than under
conventional combustion operation, while
kiln exit levels were higher, may be that
organic constituent combustion in the kiln
was more complete under pulse combus-
tion operation. More complete organic con-
stituent combustion can result in higher
CO (the final incomplete combustion prod-
uct) levels, while other unburned hydro-
carbon levels, including soot, would be
decreased. In such cases, the burden on
the afterburner to carry the destruction
process to completeness would be less-
ened, resulting in lower afterburner exit
CO levels.
The afterburner exit soot emissions data
(measured as TOC in the afterburner exit
particulate) show a consistent pattern. The
soot emission levels given in Table 3 again
represent the average of the levels mea-
sured for each of the three tests at each
respective condition, with the exception of
the level noted for Test Condition 1. The
afterburner exit particulate for only one
Test Condition 1 test was analyzed for
TOC, so the Test Condition 1 value in
Table 3 reflects only this one measure-
ment. Soot emission levels were <1.3 mg/
dscm at 7 percent O2 for Test Condition 1,
the baseline, conventional combustion test
condition. They were increased, to 1.9 mg/
dscm at 7 percent O2 (range of <0.9 to
2.7), for Test Condition 2. However, with
pulse combustion at the same feedrate
for Test Condition 3, soot emissions de-
creased to <1.0 mg/dscm at 7 percent O2
(range of<0.8 to 0.9). Even at the in-
creased waste feedrate achieved for Test
Condition 4, afterburner exit soot emis-
sions, at 1.3 mg/dscm (range of <0.9 to
1.8), were less than those measured for
Test Condition 2.
Afterburner and baghouse exit NOX
emissions were comparable from test con-
dition to test condition and were 90 and
88 ppm at 7 percent O2 (ranges of 85.5 to
93.9 and 85.8 to 91.1), respectively, for
Test Condition 1, and a slightly decreased
82 and 85 ppm at 7 percent O2, (ranges of
78.3 to 85.1 and 83.6 to 86.3) for Test
Condition 2. Levels of afterburner and
baghouse exit NOX were, respectively, 77
and 78 ppm at 7 percent O2 (ranges of
68.0 to 87.1 and 76.6 to 79.6), for Test
Condition 3 (under pulse combustion), and
78 and 72 ppm at 7 percent O2 (ranges of
73.7 to 81.4 and 68.7 to 75.5), for Test
Condition 4 (also under pulse combus-
tion). Although the Sonotech claim that
pulse combustion would result in de-
creased NOX emissions was confirmed by
the test data, the reductions achieved were
small, and from low initial NOX levels.
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Composition
No PAH or BTEX constituent, with the
exception of benzene in a few cases, was
detected in any kiln ash or scrubber liquor
sample from any test. Detection limits for
PAHs were 0.1 to 0.3 mg/kg, in kiln ash,
and 1 to 3 |ig/L, in scrubber liquor. Detec-
tion limits for BTEX constituents were 1 to
10 mg/kg, in kiln ash, and 1 to 10 (ig/L, in
scrubber liquor. Benzene was found in
the kiln ash samples from one Test Con-
dition 2 test, from one Test Condition 3
test, and from all three Test Condition 4
tests, but at levels only slightly above the
method detection limit of 1 mg/kg.
Incinerator feed, flue gas, and residue
discharge samples were analyzed for an-
timony, barium, beryllium, cadmium, chro-
mium, lead, and mercury. No antimony or
mercury was found in any test program
sample. The data show that the distribu-
tion of these metals in the kiln ash dis-
charge did not vary from test condition to
test condition. Concentrations of barium
and chromium in the scrubber liquor were
slightly lower and in the baghouse exit
flue gas were higher for the pulse com-
bustion operating conditions.
The concentrations of the five metals in
TCLP leachates of test feed, kiln ash, and
scrubber liquor samples ranged from not
detected to low. At the concentrations
measured, neither the test waste feed or
the incineration residual discharges would
be a toxicity characteristic (TC) hazard-
ous waste for any test condition, and no
significant variation in leachate concentra-
tions with test conditions was seen.
Dioxin
Chlorinated dioxins and furans were
measured in the baghouse exit flue gas
for all tests. Test condition average flue
gas concentrations are summarized in
Table 4 in terms of the two summary con-
centration measures commonly reported:
total PCDD/PCDF and 2,3,7,8-TCDD tox-
icity equivalents (TEQs). The entries in
Table 4 are cited as ranges. This arises
from the fact that, in many cases, a con-
Table 4. Dioxin/Furan Emission Results
gener group or specific isomer concentra-
tion is reported as not detected. Thus, for
concentrations reported as a range, the
low value corresponds to assuming con-
stituents not detected were present at zero
concentration; the high value corresponds
to assuming these constituents were
present at their detection limit.
The data in Table 4 show that total
PCDD/PCDF emissions at the baghouse
exit were quite low, at 0.15 ng/dscm at
7 percent O2 or less, for all test condi-
tions, and were not affected by the test
condition differences. On a TEQ basis,
emissions were 0.005 ng/dscm at 7 per-
cent O2, or less, and, again, were not
affected by the test condition differences.
Conclusions
The objectives of this test program were
to develop test data to permit the evalua-
tion of Sonotech's claims regarding the
performance of the Sonotech pulse com-
bustion technology applied to a hazard-
ous waste incinerator in comparison with
the performance of conventional combus-
tion technology. In evaluating the claims,
test data were evaluated using the rank
sum test. The rank sum test allows an
assessment of whether observed differ-
ences in data sets are statistically signifi-
cant. When comparing two data sets, each
containing three data points, the two data
sets are different, at the 95 percent confi-
dence level, when there is no data over-
lap. With respect to the Sonotech claims,
test data show that the application of the
Sonotech pulse combustion technology
resulted in:
increased incinerator capacity. Ap-
plication of the Sonotech pulse com-
bustion system allowed a waste
feedrate increase of 13 percent
compared to corresponding operat-
ing conditions under conventional
combustion. Because the waste
treated had significant heat con-
tent, the capacity increase equated
to a corresponding decrease in the
auxiliary fuel consumption per unit
of waste treated from an average
Condition average concentration,
ng/dscm at 7% O2
Test condition
Total PCDD/PCDF
TEQ
Condition 1
Condition 2
Condition 3
Condition 4
0.13to 0.15
0.092 to 0.099
0.10 to 0.11
0.13to0.14
0.0004 to 0.0054
0.0004 to 0.0050
0.0003 to 0.0041
0.0006 to 0.0046
of 21.1 kBtu/lb (range of 21.0 to
21.3kBtu/lb) to an average of
18.0 kBtu/lb (16.6 to 19.0 kBtu/lb).
Increased POHC ORE. POHC
DREs measured for all test condi-
tions were uniformly 99.994 percent
or greater, with no observable ben-
efit, or detriment, due to pulse com-
bustion. Benzene emission rates at
the afterburner exit were reduced
from an average of 7.7 mg/hr (range
of 2.1 to 12) to an average of
5.7 mg/hr (range of 3.4 to 6.9).
Naphthalene emission rates at the
afterburner exit were reduced from
an average of 1.2 mg/hr (range of
0.4 to 2.6) to an average of 1.1 mg/
hr (range of <0.3 to 2.5).
Decreased flue gas CO emissions.
Average afterburner exit flue gas
CO levels were reduced, from
20 ppm at 7 percent O2 (range of
8.0 to 40.0) in a maximum waste
feedrate operating condition under
conventional combustion operation,
to an average of 14 ppm at 7 per-
cent O2 (range of 12.6 to 16.0) at
the same feedrate with pulse com-
bustion. Pulse combustion allowed
a higher waste feedrate to be
achieved, with average afterburner
exit CO emissions of 18 ppm at
7 percent O2 (range of 10.5 to 26.0),
still below the conventional com-
bustion maximum feedrate condi-
tion.
Decreased flue gas NOX emissions.
Both afterburner exit and baghouse
exit NOX emissions were marginally
decreased from 82 (range of 78.3
to 85) to 85 (range of 83.6 to 86.3)
ppm at 7 percent O2, respectively,
in a conventional combustion maxi-
mum waste feedrate operating con-
dition, to averages of 77 (range of
68.0 to 87.1) and 78 (range of 76.6
to 79.6) ppm at 7 percent O2 at the
same feedrate with pulse combus-
tion. At the higher waste feedrate
achievable with pulse combustion,
average NOX emissions were 78
(range of 73.7 to 81.4) and
72 (range of 68.7 to 75.5) ppm at
7 percent O2.
Decreased flue gas soot emissions.
Average afterburner exit flue gas
soot emissions, measured as total
organic carbon or particulate, were
decreased from 1.9mg/dscm at
7 percent O2 (range of <0.9 to 2.7),
in the conventional combustion
maximum waste feedrate operating
condition, to <1.0 mg/dscm (range
of <0.8 to 0.9), with pulse combus-
tion at the same feedrate. Even in
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the increased-feedrate pulse com-
bustion test condition, afterburner
exit soot emissions were still lower,
at an average of 1.3mg/dscm at
7 percent O2 (range of <0.9 to 1.8),
than in the conventional combus-
tion maximum feedrate condition.
Decreased combustion air require-
ments. Total system combustion air
requirements decreased from an
average of 39,500 dscf/hr (range
of 38,400 to 40,600) under con-
ventional combustion to an aver-
age of 37,600 dscf/hr (range of
34,800 to 39,900) with pulse com-
bustion, based on stoichiometric cal-
culations.
Decreased auxiliary fuel require-
ments. No measurable change in
auxiliary fuel requirements to es-
tablish a given set of combustion
conditions was observed.
A secondary test program objective was
distribution of hazardous constituent trace
metals among the incineration system dis-
charge streams. Test data show that no
S. Venkatesh, W. E. Whitworth, Jr., C. Goldman, and L. R. Water/and are with
Acurex Environmental Corporation, Jefferson, AR 72079.
R. C. Thurnau is the EPA Project Officer; M. K. Richards is the SITE Project
Manager, (see below).
The complete report, entitled "SITE Program Evaluation of the Sonotech Pulse
Combustion Burner Technology,"(OrderNo. PB97-189732; Cost: $35.00, sub-
ject 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 and Project Manager can be contacted at
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
significant differences in metals distribu-
tions among the test conditions are ap-
parent, with the exception that barium and
chromium concentrations were slightly
lower in the scrubber liquor, and were
higher in the baghouse exit flue gas with
pulse combustion.
Although not the subject of the initially
defined project objectives, heating value
determinations performed on kiln ash resi-
due samples show that pulse combustion
operation improved residue quality by pro-
ducing a kiln ash discharge with lower
heating value than that measured in kiln
ash from conventional combustion opera-
tion. The observation that pulse combus-
tion operation caused increased kiln solids
bed temperatures, likely the result of im-
proved heat transfer to the solids bed, is
consistent with the lower-heating-value kiln
ash observed.
The full report was submitted in fulfill-
ment of Contract No. 68-C9-0038, Work
Assignments 3-4 and 4-4, by Acurex En-
vironmental Corporation under the spon-
sorship of the U.S. Environmental
Protection Agency.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-97/061
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