Grantee Research Project Results
2002 Progress Report: Products of Incomplete Combustion in the Incineration of Brominated Hydrocarbons
EPA Grant Number: R828193Title: Products of Incomplete Combustion in the Incineration of Brominated Hydrocarbons
Investigators: Senkan, Selim M.
Institution: University of California - Los Angeles
EPA Project Officer: Hahn, Intaek
Project Period: July 1, 2000 through June 30, 2003
Project Period Covered by this Report: July 1, 2001 through June 30, 2002
Project Amount: $350,000
RFA: Combustion Emissions (1999) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
Objective:
The objective of this research project is to develop fundamental and practical insights on the formation and control of potentially toxic products of incomplete combustion in the incineration of brominated hydrocarbons (BHC). Incineration is an effective treatment method for the disposal of organic hazardous wastes, including those that contain halogenated hydrocarbons. However, the combustion of halogenated hydrocarbons are associated with the formation of trace toxic byproducts, such as halogenated aromatics and polycyclic aromatic hydrocarbons (PAH), halogenated dibenzodioxins, halogenated dibenzofurans, biphenyls, and pyrenes. Because some of the isomers of these products of incomplete combustion (PIC) are potent carcinogens (Klaassen, et al., 1986), a better understanding of their origins and fate is important for the continued safe utilization of incineration technology.
To meet the objectives of this research project, we will undertake a systematic and integrated program of experimental and theoretical/computational studies pertaining to flame combustion. The specific objectives of this research project are to: (1) determine experimentally the absolute concentrations of the major, minor, and trace PIC species, as well as temperature and soot levels in the laminar premixed and diffusion flames of brominated hydrocarbons, such as CH3Br in mixtures with hydrocarbon fuels (i.e., methane, butadiene, and heptane); and (2) establish numerically both the fate and the role bromine plays in the combustion mechanisms of hydrocarbons. To accomplish these objectives, species concentrations are determined by withdrawing samples from within flames containing BHC using heated microprobes followed by gas analysis by an online high-resolution gas chromatography/quadrupole mass spectrometry (GC/QMS).
Temperature measurements also are being taken with thermocouples, using the rapid insertion technique to prevent excessive soot accumulation on thermocouple beads. An important aspect of the program is to assess how the addition of brominated compounds perturb the flame chemistry and reaction mechanisms of regular hydrocarbons. This comparative approach is used because it builds upon our knowledge base of hydrocarbon combustion kinetics and mechanisms. However, to exploit this comparative approach, the flame structures of regular hydrocarbons also must be determined first under conditions identical to the flames containing BHC. Detailed chemical kinetic mechanisms (DCKM) describing the formation and destruction of PIC in BHC-containing flames also are being developed in view of the established hydrocarbon and chlorinated hydrocarbon combustion mechanisms (Senkan, 2000).
Progress Summary:
During this project period, we conducted the first set of premixed and diffusion flame experiments with pure CH3Br in O2/Ar. Unfortunately, these flames produced excessive amounts of soot under stable fuel-rich conditions, rendering micro-probe sampling impractical when CH3Br is the only fuel used. The large orifice diameter sampling probes (e.g., 500 microns (0.5 mm)), were plugged within 100 milliseconds, preventing the acquisition of representative flame samples. These studies clearly demonstrated the need to undertake experiments where CH3Br represents a small fraction of the fuel. These and related earlier studies also demonstrated that acetylene is a major hydrocarbon intermediate product responsible for the production of aromatics, polyaromatics, dioxins, furans, PAHs, and soot. Because there exists no prior detailed flame structure for acetylene, we undertook systematic diffusion flame studies at different strain rates and carbon densities to evaluate the effects of residence time and dilution on aromatic and PAH formation.
The new stainless steel burner system also became operational at the beginning of summer 2002. The completion of these burner experiments with flames containing corrosive combustion products, such as HBr and Br2, can be conducted in a straightforward manner.
We also continued detailed kinetic modeling work in reference to the combustion of CH3Br. The mechanism involves the participation of over 40 species in over 200 reversible elementary reactions. The mechanism has been built upon H2-O2 and CH4-O2 combustion reaction mechanisms, and has been developed analogous to the CH3Cl-O3 mechanism by properly considering the C-Br, Br-Br, and H-Br bond dissociation energies (Benson, 1976). Reaction rate parameters [k = Atnexp(-E/RT)] were obtained from published and evaluated experimental data, when such information was available (Senkan, 2000; Chase, et al., 1986; Lias, et al., 1988). In the absence of experimental data, kinetic parameters were either estimated using analogies, empirical methods (Senkan, 1991), structure activity relationships (Senkan and Quam, 1992), or calculated using computational quantum chemical methods (Senkan, 1991; Ozturk, et al., 2001).
References:
Benson SW. Thermochemical Kinetics, 2nd ed. New York: Wiley Interscience, 1976.
Chase MW, Davies CA, Downey JR, Frurip DJ, McDonald RA, Syverud AN. Journal of Physical and Chemical Reference Data 1985;14(S1).
Huang J, Senkan SM. Formation of trace byproducts in the premixed flames of CH3Cl/C2H4. Environmental Science and Technology 1997;31(5):1372-1381.
Casarett LJ, Klaassen CD, Amdur AO, Doull J, eds. Casarett and Doull's Toxicology, Macmillan, NY, 1986.
Lias SG, Bartmess JE, Liebman JF, Holmes JL, Levin RD, Mallard WG. Journal of Physical and Chemical Reference Data 1988;17(S1).
Marinov NM, Pitz WJ, Westbrook CK, Vincitore AM, Senkan SM. Aromatic and polycyclic aromatic hydrocarbon formation in a laminar premixed n-butane flame. Combustion and Flame 1998;119(1-2):192-213.
Ozturk S, Onal I, Senkan S. Partial oxidation of methane on SiO2 (quartz) surface-a quantum chemical study. Industrial Engineering and Chemical Research 2000;39(2):250-258.
Senkan SM, Quam D. Correlation of reaction rate coefficients for the abstraction of hydrogen atoms from organic compounds by chlorine radical attack. Journal of Physical Chemistry 1992;96(26)10837-10842.
Senkan S. Detailed chemical kinetic modeling: chemical reaction engineering of the future. Advances in Chemical Engineering 1992;18:95-196.
Senkan S. Survey of rate constants in the C/H/Cl/O system. In: Gardiner WC Jr., ed. Gas-Phase Combustion Chemistry. Springer Verlag, 2000, pp. 389-487.
Future Activities:
The next phase of this research project will be to continue GC/QMS experiments with the CH3Br-laden flames and the determinations of the identities and absolute concentrations of trace combustion byproducts. Quantification of the GC/QMS measurements will be accomplished either by the use of direct calibration samples, when available or feasible, or by using the ionization cross-section method. The latter is a general approach, which allows the rapid determination of species concentrations within an order of magnitude. This level of accuracy should be adequate to discern the role that bromine and brominated compounds have in the production of trace byproducts in hydrocarbon combustion processes, and will be conducted first.
Further development and refinement of the reaction mechanism of combustion of CH3Br also will be pursued during the next project period. The reaction mechanism also will be combined with transport models describing the multicomponent diffusion and reaction taking place in flames, and integrated to obtain spatially resolved concentration profiles (Marinov, et al., 1998). Model predictions will then be compared to the experimental data to validate and/or modify the reaction mechanism, the rate and themochemical parameters used in the simulations.
Journal Articles on this Report : 5 Displayed | Download in RIS Format
Other project views: | All 10 publications | 6 publications in selected types | All 6 journal articles |
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Granata S, Faravelli T, Ranzi E, Olten N, Senkan S. Kinetic modeling of counterflow diffusion flames of butadiene. Combustion and Flame 2002;131(3):273-284. |
R828193 (2002) R828193 (Final) |
Exit Exit Exit |
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Inal F, Senkan SM. Effects of equivalence ratio on species and soot concentrations in premixed N-heptane flames. Combustion and Flame 2002;131(1-2):16-28. |
R828193 (2002) R828193 (Final) |
Exit Exit Exit |
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Inal F, Senkan S. Effects of oxygenate additives on polycyclic aromatic hydrocarbons (PAHs) and soot formation. Combustion Science and Technology 2002;174(9):1-19. |
R828193 (2002) R828193 (Final) |
Exit Exit |
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Inal F, Tayfur G, Senkan SM. Experimental and artificial neural network modeling study on soot formation in premixed hydrocarbon flames. Fuel 2003;82(12):1477-1490. |
R828193 (2002) R828193 (Final) |
Exit Exit Exit |
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Olten N, Senkan S. Effect of oxygen addition on polycyclic aromatic hydrocarbon formation in 1,3 butadiene counter-flow diffusion flames. Combustion and Flame 2001;125(1-2):1032-1039. |
R828193 (2002) R828193 (Final) R826730 (2000) |
Exit Exit Exit |
Supplemental Keywords:
toxic combustion byproduct, polycyclic aromatic hydrocarbon, PAH, gas chromatography, GC, quadrapole mass spectrometry, QMS, halogenated hydrocarbon, dioxin, furan, aromatic, detailed kinetic modeling, elementary reaction, soot formation, premixed flame, diffusion flame, flame sampling, detailed flame structure., RFA, Scientific Discipline, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, Environmental Chemistry, HAPS, Fate & Transport, Analytical Chemistry, chemical mixtures, Environmental Monitoring, Ecology and Ecosystems, Atmospheric Sciences, Incineration/Combustion, fate and transport, mass spectrometry, products of incomplete combustion (PIC), Dibenzofurans, hazardous waste incinerators, PAH, gas chromatography, furans, Biphenyl, hydrocarbons, dioxins, incineration, detailed chemical kinetics, toxic by-productsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.