United States National Risk Management

Environmental Protection Research Laboratory

Agency Cincinnati, OH 45268

Research and Development EPA/600/SR-97/061 September 1997

SITE Program Evaluation of the

Sonotech Pulse Combustion

Burner Technology

S. Venkatesh, W. E. Whitworth, Jr., C. Goldman, and L. R. Waterland

Project Summary

A series of demonstration tests was

performed at the Environmental Protection Agency’s (EPA’s) Incineration

Research Facility (IRF) under the Superfund Innovative Technology Evaluation (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 program 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 combustion, resulted in: decreased flue gas

NOx, CO, and soot emissions; increased

POHC DRE; decreased combustion air

requirements; decreased auxiliary fuel

requirements; and increased incinerator capacity. The waste feed for all tests

was a mixture of contaminated materials 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 test waste

consisted of soil borings and a tar

waste from an oil gasification process

obtained from an MGP site in the southeast U.S. To address the demonstration objectives 12 tests were performed

under four different test conditions.

Each condition consisted of three identical tests 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 data points, the

data sets are different, at the 95 percent confidence level, when corresponding ranges do not overlap.

The results addressing the primary

test objectives of the test 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 condition 2 to 77 ppm (range of 68.0 to

87.1 ppm) for test condition 3; the average soot emissions decreased from

1.9 mg/dscm (range of 0.9 to 2.7 mg/

dscm) to less than 1.0 mg/dscm (range

of <0.8 to 0.9 mg/dscm). Benzene DRE

for all 12 tests was greater than 99.994

percent. Naphthalene DRE 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 practically equal under conventional and

Sonotech conditions; and the waste

feedrate capacity increased by 13 percent with the Sonotech burner operational. As the demonstration waste had

a significant heat content (8,500 Btu/

lb), the capacity increase may be translated into a reduction in auxiliary fuel

needed to treat a unit mass of waste

from 21.1 kBtu/lb for conventional combustion 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
2

Project Report ordering information at

back).

Introduction

Sonotech, Inc., of Atlanta, Georgia, has

developed a pulse combustion burner technology that claims to offer benefits when

applied in a variety of combustion processes. The burner system incorporates a

pulse combustor that can be tuned to excite large-amplitude sonic pulsations inside 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 combustion.

Sonotech has targeted waste incineration as a potential application for this technology. Accordingly, to demonstrate the

claimed benefits of the technology within

a well-established forum for providing technically sound and unbiased evaluations,

Sonotech proposed a technology evaluation test series under the Superfund Innovative Technology Evaluation (SITE)

program. The Sonotech proposal was accepted, and an evaluation test program

was performed at EPA Incineration Research Facility (IRF) in Jefferson, Arkansas.

Description of the Technology

A pulse combustor typically consists of

an air inlet, a combustor section, and a

tailpipe. Periodic variations in fuel oxidation and heat release produce pulsations

in the combustor section pressure, temperature, and gas velocities. When properly applied, a pulse combustor can excite

large-amplitude (150 dB or greater) pulsations 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 retrofitted with a pulse combustion burner capable 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 combustion 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 incineration system has several significant advantages over conventional (non-pulsating)

incineration. Thus, the general objective

of the demonstration test program was to

develop the data needed to allow objective and quantitative evaluation of these

claims. Accordingly, the primary test program objective was to develop test data

to allow evaluating whether the Sonotech

pulse combustion technology applied to

the IRF RKS, when compared to conventional, non-pulsating combustion, resulted

in:

• Increased incinerator capacity or

productivity

• Increased principal organic hazardous constituent (POHC) destruction

and removal efficiency (DRE)

• Decreased flue gas CO emissions

• Decreased flue gas NOx emissions

• Decreased flue gas soot emissions

• Decreased combustion air requirements

• Decreased auxiliary fuel requirements

The secondary test program objective

was to develop test data to allow evaluating whether the application of the Sonotech

technology, when compared to conventional, non-pulsating combustion:

• Reduced the magnitude of transient

puffs of CO and total unburned hydrocarbons (TUHC)

• Allowed reduced incineration costs

• Caused significant changes in:

Figure 1. Schematic of the IRF rotary kiln incineration system.

Quench

Secondary

burner

Air

Natural

gas,

liquid

feed

Transfer

duct

Ash

bin

Afterburner Solids

feeder

Main

burner

Afterburner

extension

Rotary

kiln Natural

gas

liquid feed

Venturi

scrubber

Scrubber

liquor

recirculation

Flue gas

reheater

Ash hopper

Air

Baghouse

Carbon bed

adsorber

HEPA

filter ID fan

Stack

Atmosphere

ID fan

Rotary Kiln Incinerator Primary Air Pollution Control System

Secondary Air Pollution

Control System

Packed

Column

Scrubber

Sonotech

Burner

system

Natural

gas

Air

Solids

Bed

Feeder
3

— The distribution of hazardous

constituent trace metals among

the incineration system discharge streams (kiln bottom

ash, scrubber liquor, baghouse

flyash, and baghouse exit flue

gas)

— The leachability of the toxicity

characteristic leaching procedure (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 incineration system operating conditions were

performed:

• Test Condition 1: Conventional

combustion under baseline, typical

RKS operation (28 kg/hr [61 lb/hr])

• Test Condition 2: Conventional

combustion at the maximum RKS

waste feedrate without pulsations

(33 kg/hr [73 lb/hr])

• Test Condition 3: Sonotech pulse

combustion at nominally the same

feedrate and conditions as Test

Condition 2 (34 kg/hr [74 lb/hr])

• Test Condition 4: Sonotech pulse

combustion at the maximum RKS

waste feedrate with pulsations (37

kg/hr [82 lb/hr])

The test waste feed for all tests was a

mixture of contaminated materials from

two manufactured gas plant (MGP) Superfund 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) fiberboard containers to the kiln at virtually

any specified feed frequency. When a relatively 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 incinerator 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 operation under conventional combustion. Test

Condition 3 was at the same waste

feedrate as Test Condition 2, but with the

Sonotech pulse combustion system in operation. 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 recurred. This condition could be termed

borderline acceptable operation under

pulse combustion operation. Three test

runs (triplicate testing) at each test condition 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 mixture of materials from two MGP Superfund 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 concentrations 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 obtained from an MGP site in the southeastern United States.

The hazardous constituent contaminants

of all three test waste components were

several polynuclear aromatic hydrocarbon

(PAH) compounds, and the VOCs benzene, toluene, ethylbenzene, and xylenes

(BTEX). Although concentrations of several 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 naphthalene would be necessary to guarantee

meaningful DRE 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 analyzed for sample-matrix-specific combinations 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 emissions. Later in the test program, measuring 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 evaluated 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 Results

Incinerator Operating

Conditions

Table 1 provides a summary of the average incineration system operating conditions 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 averages were calculated for each parameter.

The data in Table 1 represent the average 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 conditions averaged close to the test program

target of 925°C (1,700°F), and that average afterburner exit gas temperatures were

right at the test program target of 1,095°C

(2,000°F). Afterburner exit flue gas O2 levels averaged close to 9 percent for all test

conditions, although slightly lower average levels existed for Test Conditions 3

and 4, the two pulse combustion test conditions.

The baseline (Test Condition 1) waste

feedrate was 27.7 kg/hr (61.0 lb/hr). This

feedrate was increased to 33.1 kg/hr

(72.8 lb/hr) to give the borderline acceptable operation associated with Test Condition 2. Test Condition 3, with the pulse

combustion system in operation, was performed 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 Condition 1 feedrate. A further 13-percent

feedrate increase over that for Test Condition 2 was possible before incinerator

operation entered the borderline acceptable regime with the pulse combustion

system in operation. Thus, with respect to

the Sonotech claim that increased incinerator capacity can be realized with pulse

combustion, test data show that a capacity increase in the range of 13 percent

(comparing Test Condition 4 to Test Condition 2) can indeed be realized.

The data in Table 1 further show that

the total system heat input needed to maintain target incineration temperatures was

relatively constant for all four test conditions at about 645 kW (2.2 MBtu/hr). Specifically comparing the auxiliary fuel use

for Test Condition 3 to that for Test Condition 2 shows that the auxiliary fuel requirements were nominally the same.
4

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, because the waste treated in these tests

had significant heat content, the capacity

increase noted above equates to a corresponding decrease in the auxiliary fuel

consumed per unit of waste treated. Comparing 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 observations suggest that the Sonotech system

produced visually improved mixing in the

kiln chamber.

With respect to combustion air requirements, 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 Residue

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 DRE 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 Condition 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 benzene 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 measured at the baghouse exit.

The kiln ash heating value data shown

in Table 1 suggest that incineration residue 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/

lb), for Test Condition 2, to <1.1 MJ/kg

(<500 Btu/lb), for Test Condition 3, at the

same nominal feedrate but with pulse combustion, was seen. The solids bed temperature 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 averaged over the flue gas sampling period

for that test. The entries in Table 1 represent 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 1. Test Condition Operating Data

Test condition average (3 tests)

12 3 4

Conventional Conventional Pulsations Pulsations

Parameter baseline max. feed feed as in 2 max. feed

Waste feedrate, kg/hr (lb/hr) 27.7 (61.0) 33.1 (72.8) 33.5 (73.6) 37.5 (82.4)

Kiln

Gas temperature, °C (°F) 935 (1,720) 940 (1,730) 925 (1,700) 925 (1,700)

Solids bed temperature, °C (°F) 965 (1,770) 990 (1,810) 1,020 (1,870) 1,030 (1,890)

Afterburner exit gas temperature, 1,095 (2,000) 1,095 (2,000) 1,095 (2,000) 1,095 (2,000)

°C (°F)

Afterburner exit O2, % 9.3 9.3 8.7 8.5

Heat input, kW (kBtu/hr)

Waste feed 153 (522) 176 (601) 184 (628) 204 (697)

Kiln auxiliary fuel

Main burner 193 (659) 148 (506) 82 (282) 60 (205)

Sonotech burner 0 (0) 0 (0) 59 (200) 59 (200)

Total kiln 193 (659) 148 (506) 141 (482) 119 (405)

Afterburner auxiliary fuel 297 (1,012) 303 (1,035) 321 (1,094) 317 (1,082)

Total auxiliary fuel 489 (1,668) 454 (1,551) 462 (1,576) 436 (1,487)

Total system heat input, kW (kBtu/hr) 642 (2,190) 630 (2,152) 646 (2,204) 640 (2,184)

Auxiliary fuel consumption per unit of 63.6 (27,400) 49.2 (21,100) 49.7 (21,400) 41.8 (18,000)

waste treated, MJ/kg (Btu/lb)
5

Table 2. Test Program POHC DRE Summary

Benzene Naphthalene

Afterburner exit Baghouse exit Afterburner exit Baghouse exit

Feed- Emission Emission Feed- Emission Emission

rate rate, DRE, rate, DRE, rate rate, DRE, rate, DRE,

g/hr mg/hr % mg/hr % g/hr mg/hr % mg/hr %

Condition 1

Test 1 253.1 44 99.99 <1.2 >99.999 378.0 6.2 99.998 5.9 99.998Test 6 253.1 7.6 8 2.1 99.999 378.0 2.9a 99.999 3.1a 99.999

Test 10 244.1 14.8 99.99 3.4 99.998 364.5 <0.3 >99.999 2.5a 99.999Average 8.9 6 2.2 99.999 3.1 99.999 3.8 99.999

99.99

4

99.99

6

Condition 2

Test 2 298.3 9.0 99.99 31.0 99.989 445.5 2.6a 99.999 6.0 99.999

Test 7 307.3 2.1 6 <0.9 >99.999 459.0 0.6a 99.999 <0.3 >99.999Test 11 289.2 12.0 99.99 0.6 99.999 432.0 0.4a 99.999 3.5a 99.999

Average 7.7 9 1.5 99.996 1.2 99.999 3.3 99.999

99.99

5

99.99

7

Condition 3

Test 3 289.2 6.9 99.99 6.4 99.997 432.0 2.5a 99.999 2.4a 99.999

Test 5 307.3 3.4 7 1.5 99.999 459.0 <0.3 >99.999 0.6a 99.999Test 9 307.3 6.7 99.99 2.9 99.999 459.0 0.5a 99.999 1.6a 99.999Average 5.7 8 3.6 99.998 1.1 99.999 1.5 99.999

99.99

7

99.99

7

Condition 4

Test 4 343.5 10.4 99.996 2.5 99.999 513.0 0.6b 99.999 1.4b 99.999

Test 8 334.4 11.7 99.996 <1.5 >99.999 499.5 0.5b 99.999 2.2b 99.999

Test 12 334.4 50.9 99.998 1.1 99.999 499.5 1.3b 99.99 0.4b 99.999

aAverage concentration of three pairs of M0030 VOST tubes.bAnalyte detected below lowest calibrated level.“<“ = Analyte below method detection limit.
6

Table 3. Continuous Emissions Monitor Data

Test condition average (3 tests)

1 2 34

Conventional Conventional Pulsations Pulsations

Constituent baseline max. feed feed as in 2 max. feed

Kiln exit:

CO, ppm at 7% O2 68 68 117 153

Afterburner exit:

CO, ppm at 7% O2 15 20 14 18

NOx

, ppm at 7% O2 90 82 77 78

Soota, mg/dscm at 7% O2 <1.3b 1.9 <1.0 1.3

Baghouse exit:

NOx, ppm at 7% O2 88 85 78 72

a

Measured as TOC in particulate.

b

Measured for only one test.

to 990°C (1,810°F) (Test Condition 2), for

conventional combustion, to 1,020°C

(1,870°F) (Test Condition 3) 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 increased heat transfer rates with pulse combustion, specifically to the solids bed, is

justified. An increase in heat transfer rate

to the solids bed would cause the increased bed temperatures seen and the

corresponding decrease in kiln ash discharge heating value.

CO, NOx, and Soot Emissions

Table 3 summarizes the continuous

emissions monitor (CEM) and soot emissions 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 combustion test conditions (1 and 2), to

117 ppm at 7 percent O2 for Test Condition 3 and to 153 ppm at 7 percent O2 for

Test Condition 4. This increase is consistent with both the kiln solids bed temperature 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 combustion 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 Condition 1, and to 20 ppm at 7 percent O2

(range of 8.0 to 40.0 ppm), for Test Condition 2. Compared to conventional combustion, pulse combustion produced

slightly lower average afterburner exit CO

levels. Comparing Test Condition 3 (pulse

combustion) to Test Condition 2 (with conventional combustion), both of which had

the same waste feedrate, shows that pulse

combustion resulted in decreased average 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 Condition 3 level, but still lower than the Test

Condition 2 level.

CO is the final incomplete combustion

product in the series of reactions that converts the carbon in organic constituents to

CO2. Thus, an explanation for why afterburner exit CO levels under pulse combustion 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 combustion operation. More complete organic constituent combustion can result in higher

CO (the final incomplete combustion product) levels, while other unburned hydrocarbon levels, including soot, would be

decreased. In such cases, the burden on

the afterburner to carry the destruction

process to completeness would be lessened, 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 measured 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 measurement. 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 decreased to <1.0 mg/dscm at 7 percent O2

(range of<0.8 to 0.9). Even at the increased waste feedrate achieved for Test

Condition 4, afterburner exit soot emissions, 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 condition 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 combustion). Although the Sonotech claim that

pulse combustion would result in decreased NOx emissions was confirmed by

the test data, the reductions achieved were

small, and from low initial NOx levels.
7

Residue Discharge

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 μg/L, in scrubber liquor. Detection limits for BTEX constituents were 1 to

10 mg/kg, in kiln ash, and 1 to 10 μg/L, in

scrubber liquor. Benzene was found in

the kiln ash samples from one Test Condition 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 antimony, barium, beryllium, cadmium, chromium, lead, and mercury. No antimony or

mercury was found in any test program

sample. The data show that the distribution of these metals in the kiln ash discharge 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 combustion 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) hazardous waste for any test condition, and no

significant variation in leachate concentrations with test conditions was seen.

Dioxin Emissions

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 concentration measures commonly reported:

total PCDD/PCDF and 2,3,7,8-TCDD toxicity equivalents (TEQs). The entries in

Table 4 are cited as ranges. This arises

from the fact that, in many cases, a congener group or specific isomer concentration is reported as not detected. Thus, for

concentrations reported as a range, the

low value corresponds to assuming constituents 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 conditions, and were not affected by the test

condition differences. On a TEQ basis,

emissions were 0.005 ng/dscm at 7 percent 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 evaluation of Sonotech’s claims regarding the

performance of the Sonotech pulse combustion technology applied to a hazardous waste incinerator in comparison with

the performance of conventional combustion technology. In evaluating the claims,

test data were evaluated using the rank

sum test. The rank sum test allows an

assessment of whether observed differences in data sets are statistically significant. When comparing two data sets, each

containing three data points, the two data

sets are different, at the 95 percent confidence level, when there is no data overlap. With respect to the Sonotech claims,

test data show that the application of the

Sonotech pulse combustion technology

resulted in:

• Increased incinerator capacity. Application of the Sonotech pulse combustion system allowed a waste

feedrate increase of 13 percent

compared to corresponding operating conditions under conventional

combustion. Because the waste

treated had significant heat content, the capacity increase equated

to a corresponding decrease in the

auxiliary fuel consumption per unit

of waste treated from an average

of 21.1 kBtu/lb (range of 21.0 to

21.3 kBtu/lb) to an average of

18.0 kBtu/lb (16.6 to 19.0 kBtu/lb).

• Increased POHC DRE. POHC

DREs measured for all test conditions were uniformly 99.994 percent

or greater, with no observable benefit, or detriment, due to pulse combustion. 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 percent O2 (range of 12.6 to 16.0) at

the same feedrate with pulse combustion. 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 combustion maximum feedrate condition.

• 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 maximum waste feedrate operating condition, 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 combustion. 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 1.9 mg/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 combustion at the same feedrate. Even in

Table 4. Dioxin/Furan Emission Results

Condition average concentration,

ng/dscm at 7% O2

Test condition Total PCDD/PCDF TEQ

Condition 1 0.13 to 0.15 0.0004 to 0.0054

Condition 2 0.092 to 0.099 0.0004 to 0.0050

Condition 3 0.10 to 0.11 0.0003 to 0.0041

Condition 4 0.13 to 0.14 0.0006 to 0.0046
8

the increased-feedrate pulse combustion test condition, afterburner

exit soot emissions were still lower,

at an average of 1.3 mg/dscm at

7 percent O2 (range of <0.9 to 1.8),

than in the conventional combustion maximum feedrate condition.

• Decreased combustion air requirements. Total system combustion air

requirements decreased from an

average of 39,500 dscf/hr (range

of 38,400 to 40,600) under conventional combustion to an average of 37,600 dscf/hr (range of

34,800 to 39,900) with pulse combustion, based on stoichiometric calculations.

• Decreased auxiliary fuel requirements. No measurable change in

auxiliary fuel requirements to establish a given set of combustion

conditions was observed.

A secondary test program objective was

distribution of hazardous constituent trace

metals among the incineration system discharge streams. Test data show that no

significant differences in metals distributions among the test conditions are apparent, 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 residue samples show that pulse combustion

operation improved residue quality by producing a kiln ash discharge with lower

heating value than that measured in kiln

ash from conventional combustion operation. The observation that pulse combustion operation caused increased kiln solids

bed temperatures, likely the result of improved heat transfer to the solids bed, is

consistent with the lower-heating-value kiln

ash observed.

The full report was submitted in fulfillment of Contract No. 68-C9-0038, Work

Assignments 3-4 and 4-4, by Acurex Environmental Corporation under the sponsorship of the U.S. Environmental

Protection Agency.

S. Venkatesh, W. E. Whitworth, Jr., C. Goldman, and L. R. Waterland 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,” (Order No. PB97-189732; Cost: $35.00, 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 and Project Manager can be contacted at

National Risk Management Research Laboratory

U.S. Environmental Protection Agency

Cincinnati, OH 45268

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

Official Business

Penalty for Private Use

$300

EPA/600/SR-97/061