![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Hazardous Waste Incineration Abstracts
Minimization of Transient Emissions from Rotary Kiln Incinerators
Paul M. Lemieux, William P. Linak, Joseph A. McSorley Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 James E. Dunn Department of Mathematical Sciences University of Arkansas Fayetteville, AR 72701
Abstract
Transient emissions of organics can occur from rotary kiln incinerators
when drums containing liquid wastes bound on sorbents are introduced
in a batch-wise fashion. Physical processes controlling the release
of waste from the sorbent material are greatly affected by the rotation
speed of the kiln and the kiln temperature. Local partial pressure
of oxygen influences the rate of oxidation of the puff formed inside
the kiln. These physical and chemical phenomena can be exploited to
effect control of transient emissions by oxygen enrichment, where
this is accomplished in either a steady or a dynamic mode.
Experimental results from a pilot-scale rotary kiln incinerator simulator
were combined with a theoretical model in order to explore the potential
of minimizing transient emissions through changes in kiln rotation
speed, kiln temperature, steady oxygen enrichment, and oxygen enrichment
in a dynamic mode. Results indicated that transient organic emissions
could indeed be minimized by changes in these kiln operating parameters,
but because of the complex interactions of physical and chemical processes
controlling emissions, the appropriate abatement procedures must be
carefully implemented.
"Development of
a Simple Indicator for Measuring the Performance of Incinerators,
Industrial Furnaces, and Boilers Burning Hazardous Waste", P.M.
Lemieux, W.P. Linak, J.A. McSorley, J.O.L. Wendt, J.E. Dunn, Paper
Presented at the AWMA Specialty Conference on Waste Combustion in
Boilers and Industrial Furnaces, Kansas City, MO, April 1990.
Development of a Simple Indicator for Measuring the Performance of Incinerators, Industrial Furnaces, and Boilers Burning Hazardous Waste
P.M. Lemieux W.P. Linak J.A. McSorley U.S. Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park, NC 27711 J.O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 J.E. Dunn Department of Mathematical Sciences University of Arkansas Fayetteville, AR 72701
Abstract
Current regulations in the Resource Conservation and Recovery Act (RCRA)
use Destruction and Removal Efficiency (DRE) of the Principal Organic
Hazardous Constituents (POHCs) in the feed as the main regulatory parameter
to determine performance of facilities incinerating hazardous waste during
a RCRA trial burn. The calculation of DRE, however, is expensive and time
consuming to perform on a regular basis, and it is impossible to measure
DRE continuously using existing on-line analyzers. In addition, DRE does
not address the issue of potential emissions of toxic compounds that can
be formed as products of incomplete combustion (PICs) during the incineration
process.
Experiments on a 73 kW (250,000 Btu/hr) rotary kiln incinerator simulator
equipped with a 58.4 kW (200,000 Btu/hr) afterburner/control temperature
tower have been performed to aid in the development of a uniform, easy-to-measure
performance indicator for comparison of transient puffs generated by batch
incineration of different types of surrogate wastes. By utilizing time-integrated
responses from process gas analyzers, rather than instantaneous or averaged
responses, it is possible to derive an indicator of the relative degree
of local oxygen starvation that waste material was exposed to while passing
through the incinerator. This indicator, the Unsatisfied Oxygen Demand
(UOD), is a quantity that reflects the fate of all carbonaceous material
initially in the feed. UOD takes into account emissions of CO, hydrocarbons,
and soot, weights them according to their stoichiometric oxygen requirements,
and compares these parameters to the stoichiometric requirements of the
initial waste. An advantage of UOD as an indicator of incinerator performance
is that it takes into account the variations in PIC speciation that result
from different waste compounds. Although the research to derive an acceptable
value for UOD is still in its infancy, the concept shows promise as a
"back of the envelope" calculation that can be done semi-continuously
without the need for sophisticated, expensive chemical analyses.
"Transient Suppression Packaging
for Reduced Emissions from Rotary Kiln Incinerators", P.M. Lemieux,
W.P. Linak, J.A. McSorley, and J.O.L. Wendt, Combust. Sci. & Tech.,
85, 1-6, p. 203, 1992.
Transient Suppression Packaging for Reduced Emissions from Rotary Kiln Incinerators
Paul M. Lemieux William P. Linak Joseph A. McSorley U.S. Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park, NC 27711 Jost O. L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721
Abstract
Experiments were performed on a 73 kW rotary kiln incinerator simulator
to determine the effect of innovative waste packaging designs on transient
emissions of products of incomplete combustion due to batch charging
of containerized liquid surrogate waste compounds bound on ground
corncob sorbent. When containers of waste are batch charged into rotary
kilns, the rupture of the container is often followed by a very rapid
evolution of any volatile compounds contained therein. This flash
vaporization/pyrolysis can result in local depletion of available
oxygen, as supplied from the primary burner. This can lead to a transient
puff of partially combusted organic material that can pass through
the primary combustion chamber, and possibly even through the secondary
combustion chamber and/or downstream pollution control equipment.
This phenomenon frequently leads to feed rate limitations based on
the volatility or heat of combustion of organic liquids inside the
containers.
EPA's Air and Energy Engineering Research Laboratory has developed
a prototype container system designed to partition the waste/sorbent
mixture within the containers that are fed into the rotary kiln. By
compartmentalizing the waste, the release of volatile compounds is
delayed over a longer period of time than when charging single-chambered
containers. Thus, the local depletion of oxygen occurs to a lesser
degree, resulting in an overall smaller transient puff. This hypothesis
is supported by both experimental results and predictions from a kiln
waste release model.
Time-integrated measurements of carbon monoxide, total hydrocarbons,
and soot have been combined into a single dimensionless indicator
of puff magnitude, the Unsatisfied Oxygen Demand (UOD). Experiments
indicate an approximate 60% reduction in the magnitude of the transient
puffs, as measured by UOD, by distributing the mass of toluene within
chambered containers.
Initial experiments have determined that it may be possible to dramatically
reduce the magnitude of transient puffs from batch charging of containerized
liquids into rotary kilns by utilizing multi-chambered containers
to retard volatilization of liquids from the ruptured container. This
concept has potential application as a means to reduce transient emissions
from rotary kiln incinerators and industrial furnaces. It also provides
a potential means to increase the feed rate of containerized volatile
waste compounds without severely depleting available oxygen.
"Application of Pulse Combustion
to Solid and Hazardous Waste Incineration," C.R. Stewart, P.M.
Lemieux, B.T. Zinn, Combust. Sci. & Tech., Vol. 94, 1993.
Application of Pulse Combustion to Solid and Hazardous Waste Incineration
Chip R. Stewart U. S. Environmental Protection Agency Region 4 Atlanta, GA 30365 Paul M. Lemieux U. S. Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park, NC 27711 Ben T. Zinn School of Aerospace Engineering Georgia Institute of Technology Atlanta, GA 30332
Abstract
A bench-scale Rotary Kiln Incinerator Simulator was retrofitted with a
frequency-tunable pulse combustor in order to enhance the efficiency of
combustion. The pulse combustor excites pulsations in the kiln and increases
the completeness of combustion by promoting better mixing within the system.
One phenomenon that is unique to batch-fed incineration systems, and rotary
kilns in particular, is the formation of transient "puffs,"
or plugs of unburned material that are formed when the instantaneous bed
waste release rate is greater than the available local stoichiometric
oxygen supplied from the primary burner. It is hypothesized that the additional
mixing induced by the pulse combustor can reduce gas-phase stratification
and enhance transport of available oxygen into the local fuel-rich zones
of the puff.
Tests were performed using toluene (C7H8) sorbed
onto a ground corn cob sorbent and placed in cardboard containers. The
burner was operated in a non-pulse mode as a baseline condition, and then
in a pulse mode in which the frequency of the pulse combustor was adjusted
to the natural frequency of the combustion chamber, creating resonant
pulsations of large magnitude. The test was also performed using polyethylene
tube bundles to simulate a solid waste and to investigate a surrogate
which produces different puff characteristics. Products of incomplete
combustion (PICs), measured as carbon monoxide (CO), total hydrocarbon
(THC), and soot, were monitored from a sample extracted immediately downstream
of the kiln, in addition to other exhaust gas species (oxygen, carbon
dioxide, nitrogen oxides).
The addition of turbulence in the rotary kiln due to high amplitude acoustic
pulsations has a strong tendency to reduce the amount of soot and/or semi-volatile
and non-volatile THC that is measured. Mass emissions of soot were consistently
reduced in all tests.
CO increased during acoustic pulsations in the toluene tests. Toluene
is a fast burning surrogate hazardous waste which preferentially forms
soot during transient puffs. The decrease in soot and apparent corresponding
increase in CO indicate that the pulsations had a beneficial effect on
the combustion process. This phenomenon could be the result of two effects:
1) either the formation of soot is being inhibited due to disruption of
the coagulation process that occurs during soot formation; or 2) the high
amplitude acoustic waves could be breaking down the boundary layer in
the local environment of the soot particles causing faster pyrolysis of
the semi-volatile organic matter into CO and THC. It is also possible
that the pulsations cause both of these effects simultaneously.
The paper also presents two newly developed parameters indicating the
severity and magnitude of the transient puff: the unsatisfied oxygen demand
and the carbon penetration, and discusses how the pulsations affect these
parameters.
"Application of Pulse Combustion
to Incineration of Liquid Hazardous Waste," C. DeBenedictis, EPA-600/R-94-060
(NTIS PB94-164415) Environmental Protection Agency, Research Triangle
Park, NC, 1994.
Application of Pulse Combustion to Incineration of Liquid Hazardous Waste
Carin DeBenedictis U. S. Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park, NC 27711
Abstract
The purpose of this study was to determine the effect of acoustic
pulsations on the steady-state operation of a pulse combustor burning
liquid hazardous waste. A horizontal tunnel furnace was retrofitted
with a liquid injection pulse combustor. The pulse combustor burned
No. 2 fuel oil that was doped with principal organic hazardous constituents
(POHCs). The POHCs that were used were carbon tetrachloride and chlorobenzene.
Baseline conditions were tested when only fuel oil was burned as well
as hazardous waste operations. For each test condition, the burner
was operated in a both a pulsing and nonpulsing mode. Large amplitude
acoustic pulsations were generated by adjusting the burner frequency
to match the natural frequency of the combustion chamber. Sampling
of the combustion gases was done to quantify organic and particulate
emissions.
The results showed Destruction and Removal Efficiency (DRE) values
that were greater than six-nines (99.9999 percent) for both pulsing
and nonpulsing operations. The pulse combustor for this study was
equipped with a fuel vaporization unit which may have enhanced the
destruction capabilities of the burner. It is not known if experiments
without a vaporizer or operating the pulse combustor under non-ideal
combustion conditions would help determine if acoustic pulsations
can improve burner performance compared to the nonpulsed operation.
"Operating Parameters to Minimize
Emissions During Rotary Kiln Emergency Safety Vent Openings,"
P.M. Lemieux, W.P. Linak, C. DeBenedictis, J.V. Ryan, J.O.L. Wendt,
and J.E. Dunn, Hazardous Waste & Hazardous Materials, Vol. 11
No. 1, 1994.
Operating Parameters to Minimize Emissions During Rotary Kiln Emergency Safety Vent Openings
Paul M. Lemieux William P. Linak U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, Research Triangle Park, NC 27711 Carin DeBenedictis U.S. Environmental Protection Agency, Region 4, Atlanta, GA 30365 Jeffrey V. Ryan Acurex Environmental Corporation, Research Triangle Park, NC 27709 Jost O.L. Wendt Department of Chemical Engineering, University of Arizona, Tucson, AZ 85721 and James E. Dunn Department of Mathematical Sciences, University of Arkansas, Fayetteville, AR 72701
Abstract
Certain designs of hazardous waste incinerator systems include emergency
safety vents (ESVs). ESVs (also called dump stacks, vent stacks, emergency
by-pass stacks, thermal relief valves, and pressure relief valves) are
regarded as true emergency devices. Their purpose is to vent combustion
gases directly from the combustion chambers to the atmosphere in the event
of a failure of other system components. This is done for operator safety
as well as to protect the incinerator and other downstream equipment from
damage. ESVs are typically required for rotary kiln and hearth incinerators
which process a portion of their waste load as bulk solids or contained
liquids introduced continuously or in batch charges. Research has been
performed at the U.S. EPA on a 73 kW (250,000 Btu/hr) rotary kiln incinerator
simulator examining optimum settings of kiln operating parameters so as
to minimize emissions during an ESV opening event. Experimental results
are interpreted in the light of previous research results on transient
"puffs." Mechanisms governing both the release of volatile matter
during an ESV event and the subsequent pyrolysis and oxidation in the
residual sorbent bed are identified. From a practical point of view, results
indicate that alteration of operator-controllable kiln parameters during
the onset of certain ESV opening events can have a significant effect
on emissions of both organics and hydrogen chloride (HCl). A low air flow
rate results in lower emissions of both organics and HCl. This hypothetical
low air flow rate could possibly be equal to the flow rate induced by
the natural draft coupled with air in-leakage. Rotational speed (RPM)
appears to have slightly different effects on organics and HCl. Whereas
emissions of HCl are minimized at a very low or non-existent RPM, emissions
of organics exhibit a minimum at a low (but non-zero) RPM, with increasing
emissions at both zero and high RPM. The use of a small afterburner to
simulate an in-stack flare during an ESV event dramatically reduced organic
emissions.
"Sorbent Capture of Nickel,
Lead, and Cadmium in a Laboratory Swirl Flame Incinerator," W.P.
Linak, R.K. Srivastava, and J.O.L. Wendt, Combustion and Flame, V. 100,
pp. 241-250, 1995.
Sorbent Capture of Nickel, Lead, and Cadmium in a Laboratory Swirl Flame Incinerator
William P. Linak Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 USA Ravi K. Srivastava Acurex Environmental Corporation P.O. Box 13109 Research Triangle Park, NC 27709 USA Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721
Abstract
The in-situ capture of toxic metals by sorbents was investigated in
a small semi-industrial-scale 82 kW research combustor. Metals considered
were nickel, lead, and cadmium. These metals were introduced into
the system as aqueous nitrate solutions, sprayed down the center of
a natural gas flame, supported on a variable swirl burner. Kaolinite,
bauxite, and hydrated lime were injected along the centerline in the
postflame, near the peak system temperature. Measurements of both
the submicron aerosol size distribution and the size segregated particulate
composition in the exhaust allowed the effects of sorbent injection
to be ascertained, both with and without the presence of chlorine.
Lead and cadmium could be almost completely scavenged by kaolinite
which formed melted particles. Bauxite, which did not melt, was exceedingly
effective in capturing cadmium. However, chlorine inhibited metal
capture in these instances. Hydrated lime also captured cadmium to
form a eutectic melt, and this process was slightly enhanced by chlorine.
Nickel alone did not significantly vaporize and was not captured by
kaolinite. However, in the presence of chlorine, nickel did vaporize
and was effectively captured. These results are interpreted and compared
to bench-scale results in the literature. Two mechanisms, or scenarios,
for toxic metal capture are presented.
"Chemical and Biological Characterization
of Products of Incomplete Combustion from the Simulated Field Burning
of Agricultural Plastic," W.P. Linak, J.V. Ryan, E. Perry, R.W.
Williams, and D.M. DeMarini, Journal of the Air Pollution Control
Association, V. 39, pp. 836-846, 1989.
Chemical and Biological Characterization of Products of Incomplete Combustion from the Simulated Burning of Agricultural Plastic
William P. Linak Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Jeffrey V. Ryan Acurex Environmental Corporation Environmental Systems Division P.O. Box 13109 Research Triangle Park, NC 27709 Erica Perry and Ron W. Williams Environmental Health Research and Testing Inc. P.O. Box 12199 Research Triangle Park, NC 27709 David M. DeMarini Genetic Toxicology Division, MD-68A Health Effects Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
Chemical and biological analyses were performed to characterize products
of incomplete combustion emitted during the simulated open field burning
of agricultural plastic. A small utility shed equipped with an air delivery
system was used to simulate pile burning and forced-air-curtain incineration
of a nonhalogenated agricultural plastic that reportedly consisted of
polyethylene and carbon black. Emissions were analyzed for combustion
gases; volatile, semi-volatile, and particulate organics; and toxic and
mutagenic properties. Emission samples, as well as samples of the used
(possible pesticide-contaminated) plastic were analyzed for the presence
of several pesticides to which the plastic may have been exposed. Although
a variety of alkanes, alkenes, and aromatic and polycyclic aromatic hydrocarbon
(PAH) compounds were identified in the volatile, semi-volatile, and particulate
fractions of these emissions, a substantial fraction of higher molecular
weight organic material was not identified. No pesticides were identified
in either combustion emission samples or dichloromethane washes of the
used plastic. When mutagenicity was evaluated by exposing Salmonella bacteria
(Ames assay) to whole vapor and vapor/particulate emissions, no toxic
or mutagenic effects were observed. However, organic extracts of the particulate
samples were moderately mutagenic. This mutagenicity compares approximately
to that measured from residential wood heating on a revertant per unit
heat release basis. Compared to pile burning, forced air slightly decreased
the time necessary to burn a charge of plastic. There was not a substantial
difference, however, in the variety or concentrations of organic compounds
identified in samples from these two burn conditions. This study highlights
the benefits of a combined chemical/biological approach to the characterization
of complex, multi-component combustion emissions. These results may not
reflect those of other types of plastic that may be used for agricultural
purposes, especially those containing halogens.
"Bioassay-Directed
Chemical Analysis of Organic Extracts from Incinerator Emissions: Combustion
of Single Compounds," D.M. DeMarini, R.W. Williams, E. Perry, P.M.
Lemieux, and W.P. Linak, Combustion Science & Technology, V. 85, pp.
437-453, 1992.
Bioassay-Directed Chemical Analysis of Organic Extracts from Incinerator Emissions: Combustion of Single Compounds
David M. DeMarini Genetic Toxicology Division, MD-68A Health Effects Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Ron W. Williams and Erica Perry Environmental Health Research and Testing Inc. P.O. Box 12199 Research Triangle Parc, NC 27709 Paul M. Lemieux and William P. Linak Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
A prototype/laboratory-scale rotary kiln (73kW, 250,000 Btu/h) was
used to examine the chemical composition and biological effects of
the effects of the emissions produced when the kiln was operated under
sub-optimal conditions resulting from batch charging. The surrogate
wastes evaluated were polyethylene (PE), polyvinylchloride (PVC),
toluene (TOL), carbon tetrachloride (CCl4), PE + PVC, and
TOL + CCl4. The dichloromethane-extractable organics from
particles (collected on filters) and semi-volatiles (collected on
XAD-2 resin) were evaluated fro mutagenic activity using the Salmonella
(Ames) mutagenicity assay in strain TA98 (+S9). The mutagenic potencies
revertants/microgram of extractable organics) of the emissions ranked
as follows: PE > TOL > PE + PVC > TOL + CCl4.
The organic extracts from the PVC and CCl4 emissions were
not mutagenic. The mutagenic emission factors (revertants/kilogram
of fuel or /megajoule of heat) for the TOL or PE emissions were similar
to those for municipal waste combustors; those for PE + PVC or TOL
+ CCl4 were similar to those for oil or coal burned in
industrial and utility boilers and power plants. These results suggest
that the mutagenic emission factors may depend as much or more on
the operating conditions of the incinerator than on the feed stock.
Extracts were fractionated by high pressure liquid chromatography
(HPLC), and each HPLC fraction was evaluated for mutagenic activity
using strain TA98(-S9) in a micro-suspension mutagenicity assay. Bioassay-directed
chemical analysis was performed by subjecting selected mutagenic fractions
to analysis by mass spectrometry. Various PAHs were identified in
mutagenic fractions of the PE emissions. This study illustrates the
value of performing both chemical and biological analyses of chemically
complex combustion emissions in order to characterize the potential
health effects of such mixtures.
"Use of Bioassay
Methods to Evaluate Incinerator Emissions," R.R. Watts, D.M.
DeMarini, W.P. Linak, P.M. Lemieux, J.A. McSorley, and J. Lewtas,
International Conference on Municipal Waste Combustion, Hollywood,
FL, April 11-14, 1989.
Use of Bioassay Methods to Evaluate Incinerator Emissions
Randall R. Watts, David M. DeMarini, and Joellen Lewtas Genetic Toxicology Division, MD-68A Health Effects Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 William P. Linak, Paul M. Lemieux and Joseph A. McSorley Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
The products of incomplete combustion from incineration include complex
mixtures of organics, particularly polycyclic aromatic compounds, which
are present after atmospheric dilution and cooling in emissions as semi-volatile
or particulate organic compounds. Combustion emissions are generally recognized
as a potential cancer risk since they contain many carcinogenic and mutagenic
polycyclic aromatic hydrocarbons. Analyzing such a complex mixture for
the presence of even a few selected chemicals is difficult and provides
risk information on only a fraction of the chemicals present. Bioassay
methods, however, may be directly applied to evaluate the mutagenic and
carcinogenic activity of the complex organics from combustion emissions.
The Salmonella (Ames) assay was used to determine the mutagenicity associated
with particles from the effluent of municipal waste combustors, from ambient
air collected near a municipal waste combustor, and from the effluent
of a laboratory-scale rotary kiln incinerator simulator in which polyethylene
was combusted. Dose-response data were generated, and mutagenicity concentrations
or mutagenic potency values were calculated.
"Measurement of Mutagenic
Emissions from the Incineration of the Pesticide Dinoseb during Application
of Combustion Modifications," D.M. DeMarini, V.S. Houk, J. Lewtas,
R.W. Williams, M.G. Nishioka, R.K. Srivastava, J.V. Ryan, J.A. McSorley,
R.E. Hall, and W.P. Linak, Environmental Science and Technology, V. 25,
pp. 910-913, 1991.
Measurement of Mutagenic Emissions from the Incineration of the Pesticide Dinoseb during Application of Combustion Modifications
David M. DeMarini, Virginia S. Houk, and Joellen Lewtas Genetic Bioassay Branch, MD-68 Health Effects Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Ron W. Williams Environmental Health Research and Testing Inc. 631 United Dr. Durham, NC 27713 Marcia G. Nishioka Battelle, Columbus Division 505 King Avenue Columbus, OH 43201 Ravi K. Srivastava, Jeffrey V. Ryan Acurex Corporation 4915 Prospectus Drive Durham, NC 27713 Joseph A. McSorley, Robert E. Hall, and William P. Linak Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
The dinitroaromatic pesticide dinoseb was incinerated in a 0.6-MW
(2,000,000 Btu/h) precombustion chamber burner / package boiler simulator
that employed two combustion-modification technologies for NOx
control, staged combustion, and/or reburning. The Salmonella (Ames)
mutagenicity Assay was used to monitor the effect of these control
technologies on the mutagenicity of the particle-bound and semivolatile
dichloromethane-extractable organics of the emissions. The combination
of staged combustion and reburning reduced not only the NOx
emissions (by >96%) compared to the absence of these two control
technologies, but also the mutagenic potency of the emissions (by
~70%, -S9) and the mutagenic emission factor (by ~60%, -S9) compared
to that of staged combustion alone. The mutagenic emission factor
in the presence or absence of S9 was similar to that obtained for
the burning of fuel oil for residential heating (~1 revertant/kg of
fuel x 1.0E5, +S9). Mutagenic bioassays suggested that ~70-90% of
the mutagenic activity of the organic emissions in the absence of
S9 may be due to nitroaromatics. However, chemical analysis for a
variety of nitroaromatics indicated the presence of only a few such
compounds at detectable levels. In the presence of S9, the mutagenic
potency of the organic emissions was increased ~50% by the addition
of reburning. This is consistent with the conversion by reburning
of nitroaromatics, which are mutagenic in the absence of S9, to polycyclic
aromatic hydrocarbons (PAHs), which are mutagenic in the presence
of S9.
"Application of
Staged Combustion and Reburning to the Co-Firing of Nitrogen-Containing
Wastes," W.P. Linak, J.A. Mulholland, J.A. McSorley, R.E. Hall,
R.K. Srivastava, J.V. Ryan, M.G. Nishioka, J. Lewtas, and D.M. DeMarini,
Hazardous Waste and Hazardous Materials, V. 8, No. 1, pp. 1-15, 1991.
Application of Staged Combustion and Reburning to the Co-Firing of Nitrogen-Containing Wastes
William P. Linak, James A. Mulholland, Joseph A. McSorley, Robert E. Hall Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Ravi K. Srivastava, Jeffrey V. Ryan Acurex Corporation 4915 Prospectus Drive Durham, NC 27713 Marcia G. Nishioka Battelle, Columbus Division 505 King Avenue Columbus, OH 43201 Joellen Lewtas, David M. DeMarini Health Effects Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
A 0.6 MW (2,000,000 Btu/hr) precombustion chamber burner, designed for
in-furnace nitrogen oxide (NOx) control, high combustion efficiency,
and retrofit applications was evaluated for use with high nitrogen content
fuel/waste mixtures. The 250- to 750-ms residence time precombustion chamber
burner mounted on a prototype watertube package boiler simulator used
air staging and in-furnace natural gas reburning to control NOx
emissions. Previous work (13) has reported on tests in which natural gas
doped with ammonia (NH3) and No. 2 distillate fuel oil doped
with pyridine (C5H5N) were used to simulate high
nitrogen content fuel/waste mixtures. The present study reports on research
in which the low NOx precombustor was used to examine the co-firing
characteristics of a nitrogen-containing pesticide, containing dinoseb
(2-sec-butyl-4,6 dinitrophenol) in a fuel-oil/xylene solvent. The
dinoseb formulation as fired contained 6.4% nitrogen. NOx emissions
without in-furnace control exceeded 4400 ppm (corrected to 0% O2).
When NOx controls in the form of air staging and natural gas
reburning were employed, these emissions were reduced to below 150 ppm
(96% reduction). Average CO and total hydrocarbon (THC) emissions were
typically less than 15 and 2 ppm, respectively. Dinoseb was not detected
in any emission sample, and the destruction efficiency (DE) was determined
to be greater than 99.99%. Mutagenicity studies of the dinoseb emissions
showed that the mutagenic emission factors measured with either air staging
or air staging and reburning were similar to those measured for the burning
of fuel oil for residential heating.
"On the Occurance of Transient
Puffs in a Rotary Kiln Incinerator Simulator: I. Prototype Solid Plastic
Wastes," W.P. Linak, J.D. Kilgroe, J.A. McSorley, J.O.L. Wendt, and
J.E. Dunn, Journal of the Air Pollution Control Association, V. 37, No.
1, pp. 54-65, 1987.
On the Occurance of Transient Puffs in a Rotary Kiln Incinerator Simulator: Prototype Solid Plastic Wastses
William P. Linak, James D. Kilgroe, and J.A. McSorley Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 James E. Dunn Department of Mathematical Sciences University of Arkansas Fayetteville, AR, 72701
Abstract
In the operation of practical rotary kiln incinerators, the hazardous
waste charge is often introduced in drums or containers in a batch
mode. The ensuing transient condition, caused by the rapid devolatilization
of waste materials, can momentarily deplete or displace local levels
of excess oxygen in the kiln, resulting in heavy transient loadings
of unburned gaseous and particulate hydrocarbons (here denoted as
"puffs") leaving the kiln. This system upset must then be
handled by an afterburner and subsequent air pollution control devices
downstream. Such an overcharging or transient condition may even result
in unacceptably low destruction of principal organic hazardous constituents
(POHC) and the formation of products of incomplete combustion (PIC).
A 73-kW(250,000-Btu/h) rotary kiln simulator was designed and constructed
to provide engineering insight into the chemical and physical parameters
associated with failure mode conditions. To this end, a statistically
designed parametric investigation was undertaken to determine which
waste and kiln variables (charge mass, charge surface area, charge
composition, and kiln temperature) significantly affect both instantaneous
intensity and total magnitude of the pollutant puffs leaving the kiln.
Emphasis was on the incineration of simple prototype plastic wastes,
ranging from polyethylene to polyvinyl chloride. Results demonstrate
the relative ease with which failure conditions are experienced, even
at high excess air values and high kiln temperatures. Transient puffs
leaving the kiln contain a number of hazardous compounds. Increasing
kiln temperature does not necessarily decrease the puff intensity
and may in fact cause an increase. However, the total mass emitted
decreases with increasing temperature. In addition, the mass, surface
area, and composition of the charge are all important.
"On the Occurance of Transient
Puffs in a Rotary Kiln Incinerator Simulator: II Contained Liquid
Wastes on Sorbent," W.P. Linak, J.A. McSorley, J.O.L. Wendt,
and J.E. Dunn, Journal of the Air Pollution Control Association, V.
37, No. 8, pp. 934-942, 1987.
On the Occurance of Transient Puffs in a Rotary Kiln Incinerator Simulator: II Contained Liquid Wastes on Sorbent
William P. Linak and J.A. McSorley Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 James E. Dunn Department of Mathematical Sciences University of Arkansas Fayetteville, AR, 72701
Abstract
The generation of transient puffs resulting from the batch introduction
of liquid waste into a 73 kW (250,000 Btu/h)) rotary kiln incinerator
simulator was investigated. The liquid was added onto a sorbent, enclosed
in cylindrical cardboard containers that were introduced into the combustion
chamber one at a time. A statistically designed parametric investigation
determined the effects of liquid mass, liquid composition, kiln temperature,
and kiln rotation speed on the total magnitude and instantaneous intensity
of the pollutant puff leaving the kiln. Liquid "wastes" investigated
included toluene, methylene chloride, carbon tetrachloride, and No. 5
fuel oil. Transient puffs from these wastes were monitored using on-line
measurements for FID-measurable hydrocarbons, CO, and integrated particulate
filter loadings, although the suitability of any one of these indicators
depended on the chemical nature of the waste involved. Results demonstrate
that puffs formed during transient conditions are generated easily, even
with small quantities of wastes and with the kiln operating at 100 percent
excess air. High kiln temperatures and increased kiln rotation speeds
exacerbated the generation of puffs, due to increased liquid evaporation
rates. Transient puffs may contain hazardous products of incomplete combustion
(PICs) even though adequate destruction and removal efficiencies are achieved.
Mixtures of chlorinated and nonchlorinated principal organic hazardous
constituents (POHCs) in the waste can lead to the formation of more diverse
chlorinated compounds that are formed from a single chlorinated POHC such
as carbon tetrachloride alone. This paper is the second of a series. Its
companion paper, Part I, which has been published previously, is concerned
with solid plastic wastes.
"Mechanisms Governing
Transients from the Batch Incineration of Liquid Wastes in Rotary Kilns,"
J.O.L. Wendt and W.P. Linak, Combustion Science and Technology, V. 61,
pp. 169-185, 1988.
Mechanisms Governing Transients from the Batch Incineration of Liquid Wastes in Rotary Kilns
Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 William P. Linak Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
When containerized liquid wastes, bound on sorbents, are introduced
into a rotary kiln in a batch mode, transient phenomena involving
heat transfer into, and waste mass transfer out of, the sorbent can
promote the rapid release of waste vapor into the kiln environment.
This rapid vapor release can cause depletion and displacement of the
excess oxygen from the primary flame, and formation of a puff, which
can result in a temporary failure of the incinerator system Parametric
studies on a specially designed rotary kiln incinerator simulator
showed that puffs are easily generated even with very small quantities
of surrogate wastes and at excess air values exceeding 100 percent.
Furthermore, their magnitudes and intensities increase with increasing
kiln temperature and kiln rotation speed.
A theoretical model describing simultaneous heat and mass transfer
through a sorbent aggregate, coupled with vapor pressure driven waste
vaporization within the sorbent aggregate, was combined with a fragmentation
model and was able qualitatively to predict experimentally observed
effects relating to puff duration, kiln rotation speed, kiln temperature,
and stoichiometric oxygen requirement of the surrogate waste. Extrapolation
of the model to conditions beyond the experimental test matrix indicated
very strong influences of waste boiling point (and consequently latent
heat), and of sorbent parameters such as overall void fraction in
the container and the sorption characteristics of the individual sorbent
particles. The theoretical results support the experimental data from
the rotary kiln incinerator simulator and suggest that the experimentally
observed trends have general practical validity. The model constitutes
a first step in being able to rank wastes and sorbent with respect
to their propensity to produce puffs.
"Prediction of
Transient Behavior during Batch Incineration of Liquid Wastes in Rotary
Kilns," J.O.L. Wendt, W.P. Linak, and P.M. Lemieux, Hazardous
Waste and Hazardous Materials, V. 7, No. 1, pp. 41-54, 1990.
Prediction of Transient Behavior during Batch Incineration of Liquid Wastes in Rotary Kilns
Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 William P. Linak and Paul M. Lemieux Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
When containerized liquid wastes, bound on sorbents, are introduced into
a rotary kiln in a batch mode, transient phenomena involving vaporization
of the waste, and mass and heat transfer into the sorbent can allow a
rapid release of waste vapor into the kiln environment, a displacement
of excess oxygen from the primary flame, and formation of a puff. This
transient puff then travels to the afterburner and, if it is too large,
can result in a failure mode of the incinerator system. Previous experimental
work by the U.S. Environmental Protection Agency on a specially designed
Rotary Kiln Incinerator Simulator has shown that, for liquid wastes, puffs
are very easily generated, and that their magnitudes and intensities increase
with increasing kiln temperature and increasing kiln rotation speed. This
paper presents a theoretical model which was designed both to provide
insight into why this is so, and to predict how the generation of puffs
in general is controlled by waste properties, sorbent properties, and
kiln operating parameters.
"Waste Characterization
and the Generation of Transient Puffs in a Rotary Kiln Incinerator Simulator,"
W.P. Linak, J.A. McSorley, J.O.L. Wendt, and J.E. Dunn, 13th Annual Research
Symposium on Land Disposal, Remedial Action, Incineration and Treatment
of Hazardous Waste, Cincinnati, OH, May 6-8, 1987.
Waste Characterization and the Generation of Transient Puffs in a Rotary Kiln Incinerator Simulator
William P. Linak and Joseph A. McSorley Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 James E. Dunn Department of Mathematical Sciences University of Arkansas Fayetteville, AR, 72701
Abstract
The batch introduction of waste-filled drums or containers into rotary
kiln incinerators can lead to transient overcharging conditions, which
are denoted as "puffs." This paper describes results of
an in-house investigation at the U.S. EPA into the waste properties
and kiln parameters that determine both the intensity and the magnitude
of transient puffs leaving the kiln. The experimental apparatus utilized
was a 73 kW (250,000 Btu/hr) laboratory rotary kiln simulator. Surrogate
solid wastes in the form of plastic rods and surrogate liquid wastes
on corncob sorbent in cardboard containers were investigated. Parametric
studies were used to determine the extent to which waste and kiln
variables (such as charge mass, charge surface area, charge composition,
kiln temperature, and kiln rotation speed) affected the intensity
(peak hydrocarbon emission) and magnitude (time-integrated hydrocarbon
emission) of puffs. Results demonstrate the relative ease with which
failure conditions are achieved, even at high excess air values and
high kiln temperatures. Chemical analysis indicates that puffs arising
from even innocuous surrogate wastes can contain numerous hazardous
compounds even though adequate DREs (>99.99%) are achieved. Increasing
kiln temperature and rotation speed can adversely affect puff intensity,
due to increased devolatilization and liquid evaporation rates. There
are large effects of waste composition and, for solid wastes, waste
surface area is a critical variable. Stoichiometric oxygen requirement
is an important variable distinguishing the transient behavior of
different kinds of wastes. Thermogravimetric analyses may be useful
in characterizing the propensity of solids to generate transient puffs,
while liquid wastes may be best characterized by their normal boiling
points and latent heats.
"Metal Aerosol Formation
in a Laboratory Swirl Flame Incinerator," W.P. Linak, R.K. Srivastava,
and J.O.L. Wendt, Combustion Science & Technology, V. 101, pp.
7-27, 1994.
Metal Aerosol Formation in a Laboratory Swirl Flame Incinerator
William P. Linak Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Ravi K. Srivastava Acurex Environmental Corporation P.O. Box 13109 Research Triangle Park, NC 27709 Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721
Abstract
Experiments were performed on an 82 kW (280,000 Btu/hr) refractory-lined
horizontal tunnel combustor to examine the aerosol particle size distribution
(PSD) produced by simulated nickel, cadmium, and lead wastes injected
into an incineration environment. Metal constituents in the form of aqueous
solutions of nickel, cadmium, and lead nitrates were introduced as secondary
sprays within a swirl stabilized natural gas diffusion flame. Aerosol
size distributions were measured at stack locations using a differential
mobility particle sizer and a cascade impactor as functions of combustor
temperature and waste chlorine content. Cadmium and lead produced emissions
of submicron metal aerosols with mass mean diameters of approximately
0.2 µm. These submicron aerosol PSDs are consistent with a mechanism
of metal vaporization followed by nucleation, condensation, and coagulation
prior to sampling. Nickel also formed submicron particles, but the PSD
was not generally consistent with a vaporization mechanism. With chlorine
present, the PSDs for all three metals were similar in shape, and could
be interpreted in light of the effect of chlorine to enhance and prolong
the presence of metals in the vapor phase, and leading to the sampling
of a less mature aerosol than that seen under baseline conditions. The
effect of chlorine on nickel partitioning was particularly significant,
and is consistent with vapor pressure predictions.
"Toxic Metal Emissions from
Incineration: Mechanisms and Control," W.P. Linak and J.O.L. Wendt,
Progress in Energy and Combustion Science, V. 19, pp. 145-185, 1993.
Toxic Metal Emissions from Incineration: Mechanisms and Control
William P. Linak Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721
Abstract
Toxic metals appear in the effluents of many combustion processes,
and their release into the environment has come under regulatory scrutiny.
This paper reviews the nature of the problems associated with toxic
metals in combustion processes, and describes where these problems
occur and how they are addressed through current and proposed regulations.
Although emphasis in this paper is on problems associated with metals
from incineration processes, conventional fossil fuel combustion is
also considered, insofar as it pertains to mechanisms governing the
fate of metals during combustion in general. This paper examines the
release of metals into the vapor phase, with the particle dynamics
of a nucleating, condensing, and coagulating aerosol that may be subsequently
formed, and with the reactive scavenging of metals by sorbents.
Metals can be introduced into combustion chambers in many physical
and chemical forms. The subsequent transformations and vaporization
of any volatile metal depends on the combustion environment, the presence
of chlorine and other species (reducing or oxidizing), on the nature
of the reactive metallic species formed within the furnace, and on
the presence of other inorganic species such as alumino-silicates.
Some insight into how these factors influence metal release can be
gained by considering the release of organic sodium during coal char
combustion.
Once vaporized, a metal vapor cloud will normally pass through its
dewpoint to form tiny nuclei, or condense around existing particles.
These aerosols are then affected by other dynamic processes (including
coagulation) as they evolve with time. This paper shows how current
mathematical descriptions of aerosol dynamics are very useful in predicting
metal aerosol size distributions in combustion systems. These models
are applied to two prototype problems, namely: the prediction of the
temporal evolution of a particle size distribution of a self-coagulating
aerosol initially composed of nuclei; and the scavenging of nuclei
by coagulation with larger sorbent particles.
A metal vapor can also react with certain alumino-silicate sorbents.
This process, which will occur at temperatures above the dewpoint,
is described, and is important, since it allows the high temperatures
in incineration processes to be exploited to allow the formation of
water unleachable metal containing compounds that can be isolated
from the environment. Future research problems are also identified.
"Rotary Kiln Incineration:
The Effect of Oxygen Enrichment on Formation of Transient Puffs during
Batch Introduction of Hazardous Wastes," W.P. Linak, J.A. McSorley,
J.O.L. Wendt, and J.E. Dunn, 14th Annual Research Symposium on Land
Disposal, Remedial Action, Incineration and Treatment of Hazardous
Waste, Cincinnati, OH, May 9-11, 1988.
Rotary Kiln Incineration: The Effect of Oxygen Enrichment on Formation of Transient Puffs during Batch Introduction of Hazardous Wastes
William P. Linak and J.A. McSorley Combustion Research Branch, MD-65 Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Jost O.L. Wendt Department of Chemical Engineering University of Arizona Tucson, AZ 85721 James E. Dunn Department of Mathematical Sciences University of Arkansas Fayetteville, AR, 72701
Abstract
Experiments on a 73kW (250,000 Btu/hr) rotary kiln incinerator simulator
equipped with a prototype oxygen enrichment burner were performed to determine
the effect of oxygen enrichment on the magnitude and intensity of transient
puffs emitted during batch introduction of contained liquid surrogate
waste (toluene) on corncob sorbent. Results show that the effect of oxygen
enrichment at constant temperature is to decrease the transient puff size
but that increases in kiln temperature associated with oxygen enrichment
can offset this and cause net increases in the transient emissions. This
effect is likely due to increases in the rate of waste volatilization.
These results were especially true for particulate matter and are consistent
with previous results without oxygen enrichment.
"Computer-Aided Data Acquisition
for Combustion Experiments," P.M. Lemieux, Scientific Computing and
Automation, Vol 9, No. 5, April 1993.
Computer-Aided Data Acquisition for Combustion Experiments
Paul M. Lemieux Air and Energy Engineering Research Laboratory, MD-65 U.S. Environmental Protection Agency Research Triangle Park, NC 27711
Abstract
The Combustion Research Branch (CRB) of the U.S. EPA's Air and Energy
Engineering Research Laboratory (AEERL) in Research Triangle Park,
NC, operates a combustion research laboratory to perform fundamental
research examining phenomena associated with combustion-generated
air pollution from a variety of processes, including the incineration
of hazardous waste. This laboratory is permitted under the Resource
Conservation and Recovery Act (RCRA) with a Research, Development,
and Demonstration (RD&D) permit, which allows a wide variety of
experiments to be performed on real or surrogate hazardous waste materials.
Ongoing research projects include studies examining trace metal aerosol
formation, capture of toxic metals in a fluidized bed, and formation
of products of incomplete combustion (PICs) from incineration processes.
This paper describes CRB's use of computer-aided data acquisition
techniques to aid its research program, in particular on the bench-scale
rotary kiln incinerator simulator (RKIS) facility.