- Email: [email protected]
Experimental and numerical study of the thermal destruction of C2H5Cl
Twenty-Third Symposium (International) on Combustion/The Combustion Institute, 1990/pp. 895-901
EXPERIMENTAL AND NUMERICAL STUDY OF THE THERMAL D E S T R U C T I O N OF C2H5CI E. M. F I S H E R
Department of Mechanical Engineering C. P. KOSHLAND
Department of Biomedical and Environmental Health Sciences M. J. HALL AND R. F. SAWYER
Department of Mechanical Engineering AND
D. LUCAS
Applied Science Division Lawrence Berkeley Laboratory University of California Berkeley, California, 94720, USA Gaseous C~H5C1 (ethyl chloride) was injected into the post-flame zone of a turbulent combustor, with equivalence ratios and residence times in the range of those encountered in hazardous waste incinerators. Temperatures below those normally associated with incineration were selected to simulate incinerator failure modes. Samples were withdrawn from the reactor and analyzed using a Fourier transform infrared spectrometer (FFIR) coupled to a longpath cell (60 cm base path length). For the highest-temperature case ( T ~ = 1225 K), destruction of the injected C~HsC1 was rapid, and the only observable product species were HCI, CO, H~O, and CO2. For cooler injection temperatures ( T ~ = 1012, 932 K), C2H4, C2H~, and C2HaC1 were observed as well, with a C2HaCI/C~H4 ratio between 0.25 and 0.5. C2HsC! injection was simulated numerically, using the experimental temperature profiles and modeling the reactor as a plug-flow device. The reaction mechanism developed by Karra et al. was expanded to distinguish between chlorinated C~ isomers. Rates for the modified reactions were chosen so that the combined reaction rate of the isomers was unchanged. This modification greatly improved the agreement between numerical and experimental results for C2H3CI, as it opened new channels for its production.
][ntroduclJon Measurements in hazardous-waste incinerators and waste-cofiring industrial boilers have demonstrated a broad range of operating conditions under which adequate destruction efficiencies are attained. 1"2 Several studies have assessed the impact of deviations from these conditions. Destruction efficiency was lowered in bench-scale simulation of various incinerator failure modes; high or low excess air flow rates, poor atomization of liquid wastes, and flame impingement on cold surfaces were considered. 3 Increased emissions have also been linked with transients in rotary kilns. 4 Poor operating conditions may lead to the formation of undesirable com895
pounds, known as products of incomplete combustion (PICs). By-product formation and its relationship to other measures of combustion performance have been a focus of several studies, notably flat-flame burner experiments, 5 non-oxidative reactor studies, 6'7 and chemical kinetic modeling, s - n Our study is concerned with waste destruction and PIC formation during deviations from optimal combustion conditions. We examine the evolution of products from a small quantity of a chlorinated hydrocarbon injected into the post-flame region of a turbulent combustor. The relatively low temperatures to which the compound is exposed are characteristic of incinerator failure conditions such as cool-wall impingement, poor mixing, transients, and
896
HAZARDOUS WASTE
poor atomization, which may produce large droplets that pass unburned through the flame zone. CaHsCI (ethyl chloride), the simplest and least toxic chlorinated Ca hydrocarbon, was selected to test our understanding of chlorinated hydrocarbon reactions. Experiment Our experiments were conducted in a stainlesssteel turbulent combustor, 3 m long with an inner diameter of 5.2 era. The residence time (tenths of seconds) and the lean equivalence ratios are typical of conditions in hazardous waste incinerators. The combustor was operated so that CaHsCI was exposed to temperatures lower than the peak temperature normally encountered in an incinerator (1600 K). la Figure 1 shows the apparatus and sampling system. A propane/air mixture is ignited, and the flame is stabilized on a screen. Secondary air is injected in the upstream direction after the flame to lower the temperature and equivalence ratio. Gaseous CaHgCI (99.7% purity) is added via four quartz injectors located 0.8 m downstream of the flame holder. Each injector has 5 holes 0.4 mm in diameter, and is oriented to inject the CaHsCI axially upstream. We examined the possibility that CaH~CI pyrolyzes in the injectors by flowing it through a heated quartz tube the same size as the injectors. For conditions similar to those in the injectors, less than 0.1% of the C2H5C1 decomposed. Sampling probes and bare type-K thermocouptes are located along the centerline of the combustor. Most of the reaction zone of the combustor is insulated. Gas sampling and measurement techniques are described by Hall et al.la Sampling are collected through quartz tubing (4.8 mm OD) inserted in the radial direction. The sample passes through type304 stainless-steel lines, a ceramic filter, a valve, and a manifold, all heated, and into a long-path cell
(Infrared Analysis, Inc.) coupled to Biorad Digilab model FTS-40 Fourier transform infrared spectrometer (FTIR). The sample temperature is 160~ at the entrance to the cell. Before measurements are taken at a given location, sample gases are pumped through the cell for five minutes, providing 35 changes of the gas. To address questions about catalytic reactions in the sampling system, some experiments were repeated with a glass sampling line. This reduced the exposure to metal from 4 to 0.4 m, and did not significantly alter the results. The FI'IR spectrometer provides simultaneous measurements of the infrared-active species present. Following is a list of species for which the FrIR was calibrated and an estimate of the detectability limit for each at 0.25 cm -1 resolution, 2.28 m pathlength, 16 scans, and 100 torr total pressure: CO: 15 ppm; Calla and Calla: 1.5 ppm; CaHsCI: 25 ppm; HCI: 20 ppm; CaHaCI: 3 ppm; CHaC1 and CHaO: 10 ppm. CHaO and CHzCI were below the detectability limit in all combustion spectra. CO2 and HaO were detected in combustion spectra, but not quantified. The uncertainty in FTIR measurements is estimated to be ---20%.
Numerical Modeling
The reactions in the combustor were modeled using CHEMKIN with the SENKIN driver program. 14 We specified the temperature profile as a function of time at a constant pressure of 1 atmosphere. The single independent variable, time, is equivalent to having axial distance as the only independent variable in steady, plug flow. The initial composition for the kinetic simulation was the equilibrium composition without C2H5C1 injection at the temperature of the injection location, and was calculated using STANJAN.15 Two published reaction mechanisms for chlorinated hydrocarbon incineration were examined. 8"11 They both include CaHsCI reactions, but neither was developed to model its combustion. Both reaction sets contain many estimated rates and rates extrapolated from low-temperature measurements. Our starting point for kinetic modeling was the FLOWREACTOR mechanism developed by Karra et al. for fuel-rich IMIXING1COMBUSTIONI--INJECTION ANDSAMPLING--I combustion of CHzC1 in a flat-flame burner, s In its PROPANE~.~ A I R ~ ETHYLCHLORIDE original form, the model severely underpredicts the TI~ ~ EXHAUST formation of CaHzC1 from CaH~Cl.16 We modified the mechanism to distinguish between isomers of all two-carbon chlorinated species. For example, CaH4C1 in the original mechanism was replaced by SAMPLINGMANIFOLDT~~ ~ ~ * ~ CHaCICHa and CH3CHCI in our version. Reaction rates are adjusted only to reflect the relative abunf dance of atoms. For example, the reaction CaHsC1 LONG PATH CEL + C1 --* CaH4CI + HC1 is divided into two reactions in our mechanism, CaHsCI + CI --* CH3CHCI + HC1, and CaHsCI + CI --* CHaCICHa Flc. 1. Schematic of experimental apparatus.
THERMAL DESTRUCTION OF C2H5C1 + HC1, with rates 2/5 and 3/5 of the original rate, respectively. The changed reactions are listed in Appendix A. Operating Conditions Experiments were performed with primary air, fuel, and C2H5C1 flowrates of 5.22, 0.262, and 0.0518 g/s, respectively in all cases; the secondary air flow was varied from 1.39 to 5.61 g/s. The residence times of C2H5C1 (assuming plug flow) ranged from 0.24 to 0.31 s. The Reynolds number, evaluated at 1000 K using the combustor inner diameter, exceeded 4100. Equivalence ratios, defined as (4Nc + NH)/(2No + Ncl), where Nj is the number of moles of element J, were between 0.40 and 0.64 after the addition of secondary air and C2H~C1. Figure 2 shows the centerline temperature profiles for three cases. Temperatures were uniform within 20 K over 90% of the radius of the combustor, and dropped by 50 to 100 K near the wall. Measured temperatures were fit to a quadratic, and each expression for temperature as a function of distance was converted into a function of time from C2HsC1 injection, assuming ideal gas behavior and plug flow. These three cases are representative of conditions where virtually all, most, or some of the injected C2H5C1 reacts. When the temperature at the injection site exceeded 1050 K, ignition of the C2H5C1 was inferred from a significant rise in temperature at the first thermocouple downstream of the injectors. The ignition was confirmed visually in a separate experiment. When a flame was pres-
v. ~
1100
kl_l rr" I--or" tJJ
a_
900
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70C
I
0 0.1 0.2 0.3 TIME FROM C2HSCL INJECTION [s) FIG. 2. Measured centerline temperatures as a function of time from C2H5C1 injection for three sets of operating conditions; curves are fits to the data.
897
ent, complete destruction of C2HsCI was always observed, and no products of incomplete combustion other than CO were seen. The maximum temperature experienced by the C2HsC1 in these cases could be much higher than the measured value of 1240 K. Results and Discussion
Experimental: The extent to which the injected CzHsC1 has mixed with the propane/air combustion products at each sampling location affects the measured concentrations of products. An index of mixing is the ratio of the mass fraction of chlorine measured to the mass fraction for perfectly mixed gases. This ratio was between 1.7 and 2.5 at the first sampling location; farther downstream it approaches a constant (between 1.1 and 1.4). Sampling or calibration errors, or leaks in the preignition section may account for its difference from one. We confirmed that the changes in this ratio were due to mixing, and not to sampling effects or conversion to undetected compounds, by injecting NO instead of C2H5C1. Since NO does not react at these temperatures, its concentration at a given location reflects the mixing there. NO experiments under the low-temperature conditions agreed well with the chlorine results. Figure 3 shows normalized mole fractions of the monitored species, obtained by dividing measured mole fractions by the mixing ratio described above. In the highest-temperature case (Fig. 3a), C2H5C1 is destroyed thoroughly: none is detected 0.01 seconds after injection. Since HCI is the only chlorinated species, normalization produces a constant HCI mole fraction. CO is detected at the first few sampling locations. When the destruction of C2HnCI is less complete, a greater variety of products is observed. The medium- and low-temperature cases have destruction efficiencies of 90% and 50%. In order of abundance, the products are: HCI, CO, C2Ha, C2H3C1, and C2H2. C2HzCI is present at similar final values in the two cases, and accounts for 4.5% of the injected chlorine. Figure 4 shows the outlet levels of CzHzCI and CzHa as a fraction of the initial C2H5C1 level, plotted versus the maximum measured temperature. The highest C2H3C1 level measured was 7.6% at 1005 K. Over the range in which significant quantities are present, the ratio of C2HzCI to CzH4 increases with temperature, from 0.25 to 0.5. To test the hypothesis that the precursors of C2H3C1 were C2H4 and HCI produced from the breakdown of C~HsC1, we simultaneously injected equal quantities of HCI and CzHa. Under conditions which had produced CzHzC1 from CzHsCI, no measurable C~HzCI was observed.
898
HAZARDOUS WASTE
0.20 z H ._1
-3A CO
,.c,
0 C2HSCL
OCc;:C__C
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d
-
0.15
0.10
k-= o
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~0 I000 i i 0 0 1200 1300 MAXIMUM TEMPERATURE (K) FIG. 4. Normalized mole fraction CaH4 and C~H3C1 at outlet divided by normalized mole fraction C2H~CI injected, vs. maximum measured temperature.
(.~ cl .-J -6
Cb)
-3 -z
m
~
~
j
-
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(c) mS ~
u
0 0.1 0.2 0.3 TIME FROM C2HBCL INJECTION (s) FIc. 3. Normalized measured mole fractions as a function of time after C2H5C1 injection, a) high temperature; b) intermediate temperature; c) low temperature.
(destruction efficiency 99%). Important products are HCI, CO, and C2H2, which increase in concentration throughout the simulation, and C~H4 and C~HaCI, which go through maxima. The lowesttemperature case (Fig. 5c) has a destruction efficiency of only 25%, with the same decomposition products. Although much less CzHsCI decomposes, the final C~HaCI level is higher than in the intermediate-temperature case. We have determined the most important reaction pathways in the kinetic simulation by examining the contribution of each reaction to the formation or destruction of particular species. In our mechanism, the breakdown of C2HsCI proceeds primarily through three reactions: HCI elimination and Cl radical attack forming CH2C1CHz and CHaCHC1. CaH5CI ~ C2H4 + HCI, CaH~CI + C1 ~ CH2CICH2 + HCI, CaHsCI + ~ CH3CHCI + HC1.
Numerical Modeling: Figure 5 presents some numerical modeling resuits. At high temperatures (Fig. 5a), the C~HsCI mole fraction drops abruptly to below parts per billion, and HC1 forms rapidly. CO rises abruptly and then falls gradually. A spike in the C2H4 mole fraction, attaining a value of 0.001, occurs in the first millisecond, but is indistinguishable from the y-axis in the figure. At intermediate temperatures, the destruction of C~H~CI is slower and less complete
OH radical attack is next in importance. The CHzCICHz and CHaCHC1 radicals decompose unimolecularly to form C2H4 and C2HaCI, respectively. C2H4 and C2HzC1 then react to varying degrees via radical attack. At high temperatures, conversion to CO2 is virtually complete. In the intermediate-temperature case, the bulk of the carbon is in the form of CO at the outlet, while at low temperatures carbon remains largely in the form of C2HsCI, C2H4, and C2HzCI.
THERMAL DESTRUCTION OF CzHsC1
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899
our experiments cannot prove that these isomers are crucial to the formation of CzHaCI, we have shown experimentally that reactions of HCI and CgH4 are not the route of CgHaCI production. It appears that CHCICH3 may.be a significant species in the formation of CzHaCI, since C--CI bond fissure (producing the energetically unfavored biradical CHaCH) is not the sole decomposition route. Niedzielski et al. 19 have measured rates of formation of CHCICH3 via abstraction of H from C2H5C1 by CI atoms near room temperature; although the alpha site, containing the C--CI bond, is favored by a factor of 5 at 280 K, the ratio decreases with temperature. The distribution of CzHsC1 decomposition produets is extremely sensitive to temperature in the range studied here. Thus assumptions made in modeling the flow and temperature field of the combustor may have a substantial impact on calculated mole fractions. The considerable uncertainties in the mechanism and rates also contribute to differences between measured and calculated composition. We have not attempted to fit the modeling result to our experiments. The only changes in the mechanism were to account for the different isomers containing chlorine.
-
4_
0 0.1 0.2 0.3 TIME FROM C2HSCL INJECTION (s) FIG. 5. Calculated mole fractions as a function of time after CzHsC1 injection, a) high temperature; b) intermediate temperature; c) low temperature.
Discussion:
The observation of C2H3C1 (vinyl chloride) was unexpected, and of considerable interest because the compound is a known human carcinogen and because its synthesis could be of practical value. Its formation from C2H5C1 had been observed in an adiabatic compression/expansion system 17 but in later experiments in the absence of oxygen it was attributed to catalytic effects. 18 Our modified mechanism predicts CzHaCI formation at levels within a factor of 3 of measured values, significantly better agreement than the original mechanism, which does not distinguish between Ca chlorinated isomers. While
Conclusions In the temperature range 900-1050 K, large quantities of C2HzCI (vinyl chloride) were observed experimentally, accounting for up to 7.6% of the chlorine injected as CgHsCI. C2H5C1 does not simply decompose to C2H4 and HCI, as was expected. Our modified kinetics mechanism, which distinguishes between C2 chlorinated isomers, predicts higher levels of C2HaCI than previous available mechanisms. This significantly improves agreement with experimental results for CzHzC1. The production of C~H3C1 from CsHsCI demonstrates that it is possible to form hazardous compounds from relatively innocuous chlorinated species. Acknowledgments
We thank Murray Thomson and Karim Taga for their help with the experiment. This study benefited from conversations with Drs. Selim Senkan, David Golden, Gary Miller, William Pitz, Frank Tulley, and Charles Westbrook. This research was supported by the National Institutes of Environmental Health Sciences Superfund Research Program, grant number P42 ES047050-01. E. Fisher was supported by a scholarship from the Air and Waste Management Association.
900
HAZARDOUS WASTE REFERENCES
1. MASON, H. B., NICHOLSON, J. A., DEROSmR, R. J., AND WOLBACH, C. D.: Pilot Scale Testing of Non-steady Boiler Waste Cofiring. Paper presented at the International Symposium on Incineration of Hazardous, Municipal, and Other Wastes, American Flame Research Committee Fall Meeting, Palm Springs, CA, 1987. 2. CUNDY, V. A., LESTER, T. W., STERLING, A. M., MONTESTRUC, A. N., MORSE, J. S., LEGER, C. B., AND ACHARYA, S.: J. Air Pollut. Control Assoc. 39, 944 (1989). 3. KRAMLICH, J. C., HEAP, M. P., SEEKER, W. R., AND SAMUELSEN, G. S.: Twentieth Symposium (International) on Combustion, p. 1991, The Combustion Institute, 1985. 4. WENDT, J. O. L. AND LINAK, W. P. : Comb. Sei. Tech. 61, 169 (1988). 5. SENSER, D. W., MORSE, J. S., AND CUNDY, V. A.: Hazard. Waste and Hazardous Materials 2, 473 (1985). 6. TAYLOR, P. H. AND DELLINGER, B.: Envirn. Sci. Tech. 22, 438 (1988). 7. RrrrER, E. R., BOZZELLI, J. W., AND DEAN, A. M.: Kinetic Study on Thermal Decomposition of Chlorobenzene Diluted in Ha. to appear in J. Phys. Chem. (1990). 8. KARBA, S. B., GUTMAN, D., AND SENKAN, S. M.: Comb. Sci. Tech. 60, 45 (1988). 9. CHANG, W. D., KARRA, S. B., AND SENKAN, S. M.: Comb. Sci. Tech. 49, 107 (1986). 10. TSANG, W. : Mechanisms for the Formation and Destruction of Chlorinated Organic Products of Incomplete Combustion. Paper presented at the First International Congress on Toxic Combustion Byproducts, Los Angeles, CA, August 1989. 11. MILLER, G. P., LESTER, T. W., AND CUNDY, V.
12. 13.
14.
15.
16.
17.
18.
19.
A. : A Computational Simulation of Carbon Tetr a c h l o r i d e / M e t h a n e / A i r Flames. Paper pres e n t e d at t h e A m e r i c a n C h e m i c a l Society Meeting, Dallas, TX, April 1989. OPPELT, E. T.: J Air Pollut. Control Assoc., 37, 558 (1987). HALL, M. J., LVCAS, D., TAGA, K., AND KOSHLAND, C. P.: Measuring Chlorinated Hydrocarbons in Combustion using FTIR Spectroscopy. Paper 89-53 presented at the 1989 Fall Meeting of the Western States Section/The Combustion Institute, Livermore, CA, October 1989. LUTZ, A. E., KEE, R. J., AND MILLER, J. A.: SENKIN: A Fortran Program for Predicting Homogeneous Gas Phase Chemical Kinetics with Sensitivity Analysis. Sandia Report SAND878248, 1988. REYNOLDS, W. C.: S T A N J A N - - I n t e r a c t i v e Computer Programs for Chemical Equilibrium Analysis. Thermosciences Division, Department of Mechanical Engineering, Stanford University, 1981. FISHER, E. M., KOSHLAND, C. P., HALL, M. J., AND SAWYER, R. F.: Experimental and Numerical Study of the Thermal Destruction of Chlorinated Hydrocarbons I . - - E t h y l Chloride. Paper 89-98 presented at the 1989 Fall Meeting of the Western States Section/The Combustion Institute, Livermore, CA, October 1989. GORSHKOV, S. V., KOLBANOVSKII, Yu.A., ROZOVSKII, A.YA., AND CHERNYAK, N.YA.: Kinet. Katal. 24, 253 (1983). GORSHKOV, S. V., KOLBANOVSKII, Yu.A., RozovSKn, A.YA., AND CHERNYAK, N.YA.: Kinet. Katal. 27, 263 (1986). NIEDZaELSrd, J., TSCHUIKOW-ROux, E., AND YANO, T.: Int. J. Chem. Kinet. 16, 621 (1984).
Appendix A. Changes to the Reaction Mechanism of K a r r a et al. s Modified reaction rates (k = AT" e x p ( - E / R T ) ) (cm, cal, s, mole units) Reaction as listed originally CH2CI+CHaCI=CaH4Cla CHaCI+CHaCI=CaH4CI+C1 CzHsCI+ H = C a H 4 C l + Ha CaHsCI+CI=CaH4CI+HC1 CaHsC1 + CHa~CaH4CI + CH4 C2HsCI+CHaCI =C2H4CI+CH3CI CaHsCI+O=CaH4CI+OH
Modified reaction(s) CH2C1 + CH2C1--CH2C1CH2C1 CH2CI + CH2CI=CH2C1CHa + CI C2H5C1 + H=CHaCICH2 + Ha CaH~CI + H = C H 3 C H C 1 + Ha CaH~C1 + CI=CH2CICHa + HCI CaHsC1 + CI=CH3CHC1 + HCI CaHsCI + CH3=CHaC1CHa + CH4 CaHsC1 + C H a = C H 3 C H C I + CH4 C2H5C1 + CHaCI=CHzC1CH2 + CH3C1 CaHsCI + CHaCI=CH3CHC1 + CH3C1 CaHsC1 + O=CHaCICH2 + OH CaHsC1 + O = C H 3 C H C I + OH
A
n
E
1.100E36 1.910E17 3.000E13 2.000E13 8.460E12 5.640E12 6.000Ell 4.000Ell 1.896E12 1.264E12 4.656E13 3.104E13
- 7.200 -1.013 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
8600 9655 10000 10000 616 616 8500 8500 9000 9000 6600 6600
THERMAL DESTRUCTION O F C~HsC1
901
Appendix A, (Cont.) Modified reaction rates (k = AT" exp(-E/RT)) (cm, cal, s, mole units) Reaction as listed originally C~HsCI+OH~CzH4CI+H~O CzH4CI~CzHaCI+HCI C~H4CI~+H~CzH4CI+HC1 C~H4CI~+H~C~HaC~+ H~
C2H4CI~+CI=C~HaCI~+HCI
CzH.Ci~ + CHa=CzHaCI~ + CH~
CaH~Cla + CH~CI ~CzHaCI~ + CHaC1
CzH~Cla + O=CzHaCI2 + OH
C~H4CI~+ OH=C~HaCI2 + HzO
CzH4CI~C~H~ + CI C~H4C1 + H ~ C ~ H . + HC1 CzH4C1 + CI~C~H3C1 + HCI C~HaCI~C~HaC1 + C1 C~H3CI~ + H~C~H3CI + HCI C~HaC1 + H~C~HzCI + Hz C~HaC1 + CI~C2H~C1 + HCI C~H3C1 + CHa~CzHzCI + CH4 CzHaCI + CHIC1 ~C~HzCI + CHaCI C~HaC1 + OH~C2H~CI + H~O CgH~ + CI~C~H~C1 C~H~CI + O ~ C H C 1 0 + CHO C~H~C1 + O~C2H~O + C1
Modified reaction(s)
A
C2H5C1 + OH=CHzC1CH2 + H20 C~HsC1 + O H = C H a C H C I + HzO CHC12CHa=C~H3CI + HC1 CH2C1CH2CI=C2H3C! + HCI CH2C1CH2CI + H = C H 2 C I C H z + HC1 CHC12CHa + H=CHaCHC1 + HC1 CHC12CHa+ H=CHaCCI2 + H2 CHC12CHa+ H=CHCI~CH2+ H~ CH2C1CH2C1 + H=CH2C1CHCI+ H2 CHC12CHa + CI=CHaCCI2 + HCI CHCI~CH3 + CI=CHCIzCH2 + HCI CH2C1CH2CI + CI=CH2C1CHC1 + HC1 CHCI~CHa + C Ha=CHaCCI2 + CH4 CHCI2CHa + CHa=CHC12CH2 + CH4 CH2C1CHzC1 + CH3=CH2C1CHC1 + CH4 CHC12CH3 + CH2CI=C H3CClz + CHaCI CHCI2CH3 + CHzCI=CHCI2CHz + CH3C1 CH2C1CH2CI + CH2C1 =CH2C1CHC1 + CHaC1 CHC12CH3 + O = C HaCCI~ + OH CHC12CH3 + O = C HClzCH~ + OH CH~C1CH2CI + O=CH2C1CHC1 + OH CHC12CHa + OH=CHaCC12 + H20 CHC12CH3 + OH=CHC12CHz + H20 CH2C1CH~CI+ OH=CH~C1CHC1 + H:O CHzCICH~=CzH4 + CI CH3CHCI-~C~HaC1 + H CH~CICHz+ H=C~H4+ HC1 CH~CICH~ + CI=CzHaCI + HCI CH3CHCI + CI=C~H3C1 + HC1 CH~C1CHCI=C~HaCI + C1 CHCI~CH2=C~HaC1 + C1 CHCleCH~ + H=CzHaC1 + HC1 CH~C1CHC1 + H=C~HaC1 + HC1 C~HaC1 + H = C H C I C H + H2 C~HaC1 + H=CH~CC1 + H~ CzH3CI + CI=CHC1CH + HCI C~H3CI + CI=CH~CCI + HCI C~HaCI + C H 3 = C H C I C H + CH4 CzHaC1 + C H a = C H z C C I + CH4 CzH3CI + C H z C I = C HC1CH + CHaCI C~HaC1 + CH~CI=CH~CCI + CHaCI CzHaC1 + O H = C H C I C H + H~O CzHaC1 + OH~CH2CC1 + H~O C~H2 + C I = C H C I C H CHC1CH + O 2 = C H C 1 0 + CHO CH~CCI + O z = C H C I O + CHO CHCICH + O=C~HzO + C1 CH~CC1 + O=C2H20 + C1
3.000E13 2.000E13 6.610E13 6.610E13 6.310E13 6.310E13 1.250E13 3.750E13 5.000E13 6.275E12 1.882E13 2.510E13 2.500Ell 7.500Ell 1.000El2 7.900Ell 2.370E12 3.160E12
*This rate was chosen to be the same as the rate for C2Hs=CgH4 + H.
1.250E13 3.750E13 5.000E13 9.950E 12 2.985E13 3.980E13 1.050E20 7.000E25 3.160E12 1.000El3 1.000El3 4.950E20 4.950E20 1.000El3 1.000El3 6.667E13 3.333E13 6.667E13 3.333E13 6.667Ell 3.333Ell 6.667Ell 3.333Ell 3.333E 13 1.667E13 5.130E18 2.000E12 2.000E12 3.000E13 3.000E13
n .000 .000 -.084 -.084 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
E 4000 4000 58000 58000 8400 8400 10000 10000 10000 3100 3100 3100 8500 8500 8500 9000 9000 9000
.000 7000 .000 7000 .000 7000 .000 4000 .000 4000 .000 4000 -2.360 22000 -4.100 42984* .000 0 .000 3000 .000 3000 -2.350 20000 -2.350 20000 .000 1000 .000 1000 .000 10000 .000 10000 .000 5000 .000 5000 .000 11000 .000 11000 .000 12000 .000 12000 .000 3000 .000 3000 -2.740 -1779 .000 0 .000 0 .000 0 .000 0
EXPERIMENTAL AND NUMERICAL STUDY OF THE THERMAL D E S T R U C T I O N OF C2H5CI E. M. F I S H E R
Department of Mechanical Engineering C. P. KOSHLAND
Department of Biomedical and Environmental Health Sciences M. J. HALL AND R. F. SAWYER
Department of Mechanical Engineering AND
D. LUCAS
Applied Science Division Lawrence Berkeley Laboratory University of California Berkeley, California, 94720, USA Gaseous C~H5C1 (ethyl chloride) was injected into the post-flame zone of a turbulent combustor, with equivalence ratios and residence times in the range of those encountered in hazardous waste incinerators. Temperatures below those normally associated with incineration were selected to simulate incinerator failure modes. Samples were withdrawn from the reactor and analyzed using a Fourier transform infrared spectrometer (FFIR) coupled to a longpath cell (60 cm base path length). For the highest-temperature case ( T ~ = 1225 K), destruction of the injected C~HsC1 was rapid, and the only observable product species were HCI, CO, H~O, and CO2. For cooler injection temperatures ( T ~ = 1012, 932 K), C2H4, C2H~, and C2HaC1 were observed as well, with a C2HaCI/C~H4 ratio between 0.25 and 0.5. C2HsC! injection was simulated numerically, using the experimental temperature profiles and modeling the reactor as a plug-flow device. The reaction mechanism developed by Karra et al. was expanded to distinguish between chlorinated C~ isomers. Rates for the modified reactions were chosen so that the combined reaction rate of the isomers was unchanged. This modification greatly improved the agreement between numerical and experimental results for C2H3CI, as it opened new channels for its production.
][ntroduclJon Measurements in hazardous-waste incinerators and waste-cofiring industrial boilers have demonstrated a broad range of operating conditions under which adequate destruction efficiencies are attained. 1"2 Several studies have assessed the impact of deviations from these conditions. Destruction efficiency was lowered in bench-scale simulation of various incinerator failure modes; high or low excess air flow rates, poor atomization of liquid wastes, and flame impingement on cold surfaces were considered. 3 Increased emissions have also been linked with transients in rotary kilns. 4 Poor operating conditions may lead to the formation of undesirable com895
pounds, known as products of incomplete combustion (PICs). By-product formation and its relationship to other measures of combustion performance have been a focus of several studies, notably flat-flame burner experiments, 5 non-oxidative reactor studies, 6'7 and chemical kinetic modeling, s - n Our study is concerned with waste destruction and PIC formation during deviations from optimal combustion conditions. We examine the evolution of products from a small quantity of a chlorinated hydrocarbon injected into the post-flame region of a turbulent combustor. The relatively low temperatures to which the compound is exposed are characteristic of incinerator failure conditions such as cool-wall impingement, poor mixing, transients, and
896
HAZARDOUS WASTE
poor atomization, which may produce large droplets that pass unburned through the flame zone. CaHsCI (ethyl chloride), the simplest and least toxic chlorinated Ca hydrocarbon, was selected to test our understanding of chlorinated hydrocarbon reactions. Experiment Our experiments were conducted in a stainlesssteel turbulent combustor, 3 m long with an inner diameter of 5.2 era. The residence time (tenths of seconds) and the lean equivalence ratios are typical of conditions in hazardous waste incinerators. The combustor was operated so that CaHsCI was exposed to temperatures lower than the peak temperature normally encountered in an incinerator (1600 K). la Figure 1 shows the apparatus and sampling system. A propane/air mixture is ignited, and the flame is stabilized on a screen. Secondary air is injected in the upstream direction after the flame to lower the temperature and equivalence ratio. Gaseous CaHgCI (99.7% purity) is added via four quartz injectors located 0.8 m downstream of the flame holder. Each injector has 5 holes 0.4 mm in diameter, and is oriented to inject the CaHsCI axially upstream. We examined the possibility that CaH~CI pyrolyzes in the injectors by flowing it through a heated quartz tube the same size as the injectors. For conditions similar to those in the injectors, less than 0.1% of the C2H5C1 decomposed. Sampling probes and bare type-K thermocouptes are located along the centerline of the combustor. Most of the reaction zone of the combustor is insulated. Gas sampling and measurement techniques are described by Hall et al.la Sampling are collected through quartz tubing (4.8 mm OD) inserted in the radial direction. The sample passes through type304 stainless-steel lines, a ceramic filter, a valve, and a manifold, all heated, and into a long-path cell
(Infrared Analysis, Inc.) coupled to Biorad Digilab model FTS-40 Fourier transform infrared spectrometer (FTIR). The sample temperature is 160~ at the entrance to the cell. Before measurements are taken at a given location, sample gases are pumped through the cell for five minutes, providing 35 changes of the gas. To address questions about catalytic reactions in the sampling system, some experiments were repeated with a glass sampling line. This reduced the exposure to metal from 4 to 0.4 m, and did not significantly alter the results. The FI'IR spectrometer provides simultaneous measurements of the infrared-active species present. Following is a list of species for which the FrIR was calibrated and an estimate of the detectability limit for each at 0.25 cm -1 resolution, 2.28 m pathlength, 16 scans, and 100 torr total pressure: CO: 15 ppm; Calla and Calla: 1.5 ppm; CaHsCI: 25 ppm; HCI: 20 ppm; CaHaCI: 3 ppm; CHaC1 and CHaO: 10 ppm. CHaO and CHzCI were below the detectability limit in all combustion spectra. CO2 and HaO were detected in combustion spectra, but not quantified. The uncertainty in FTIR measurements is estimated to be ---20%.
Numerical Modeling
The reactions in the combustor were modeled using CHEMKIN with the SENKIN driver program. 14 We specified the temperature profile as a function of time at a constant pressure of 1 atmosphere. The single independent variable, time, is equivalent to having axial distance as the only independent variable in steady, plug flow. The initial composition for the kinetic simulation was the equilibrium composition without C2H5C1 injection at the temperature of the injection location, and was calculated using STANJAN.15 Two published reaction mechanisms for chlorinated hydrocarbon incineration were examined. 8"11 They both include CaHsCI reactions, but neither was developed to model its combustion. Both reaction sets contain many estimated rates and rates extrapolated from low-temperature measurements. Our starting point for kinetic modeling was the FLOWREACTOR mechanism developed by Karra et al. for fuel-rich IMIXING1COMBUSTIONI--INJECTION ANDSAMPLING--I combustion of CHzC1 in a flat-flame burner, s In its PROPANE~.~ A I R ~ ETHYLCHLORIDE original form, the model severely underpredicts the TI~ ~ EXHAUST formation of CaHzC1 from CaH~Cl.16 We modified the mechanism to distinguish between isomers of all two-carbon chlorinated species. For example, CaH4C1 in the original mechanism was replaced by SAMPLINGMANIFOLDT~~ ~ ~ * ~ CHaCICHa and CH3CHCI in our version. Reaction rates are adjusted only to reflect the relative abunf dance of atoms. For example, the reaction CaHsC1 LONG PATH CEL + C1 --* CaH4CI + HC1 is divided into two reactions in our mechanism, CaHsCI + CI --* CH3CHCI + HC1, and CaHsCI + CI --* CHaCICHa Flc. 1. Schematic of experimental apparatus.
THERMAL DESTRUCTION OF C2H5C1 + HC1, with rates 2/5 and 3/5 of the original rate, respectively. The changed reactions are listed in Appendix A. Operating Conditions Experiments were performed with primary air, fuel, and C2H5C1 flowrates of 5.22, 0.262, and 0.0518 g/s, respectively in all cases; the secondary air flow was varied from 1.39 to 5.61 g/s. The residence times of C2H5C1 (assuming plug flow) ranged from 0.24 to 0.31 s. The Reynolds number, evaluated at 1000 K using the combustor inner diameter, exceeded 4100. Equivalence ratios, defined as (4Nc + NH)/(2No + Ncl), where Nj is the number of moles of element J, were between 0.40 and 0.64 after the addition of secondary air and C2H~C1. Figure 2 shows the centerline temperature profiles for three cases. Temperatures were uniform within 20 K over 90% of the radius of the combustor, and dropped by 50 to 100 K near the wall. Measured temperatures were fit to a quadratic, and each expression for temperature as a function of distance was converted into a function of time from C2HsC1 injection, assuming ideal gas behavior and plug flow. These three cases are representative of conditions where virtually all, most, or some of the injected C2H5C1 reacts. When the temperature at the injection site exceeded 1050 K, ignition of the C2H5C1 was inferred from a significant rise in temperature at the first thermocouple downstream of the injectors. The ignition was confirmed visually in a separate experiment. When a flame was pres-
v. ~
1100
kl_l rr" I--or" tJJ
a_
900
W I--.-
70C
I
0 0.1 0.2 0.3 TIME FROM C2HSCL INJECTION [s) FIG. 2. Measured centerline temperatures as a function of time from C2H5C1 injection for three sets of operating conditions; curves are fits to the data.
897
ent, complete destruction of C2HsCI was always observed, and no products of incomplete combustion other than CO were seen. The maximum temperature experienced by the C2HsC1 in these cases could be much higher than the measured value of 1240 K. Results and Discussion
Experimental: The extent to which the injected CzHsC1 has mixed with the propane/air combustion products at each sampling location affects the measured concentrations of products. An index of mixing is the ratio of the mass fraction of chlorine measured to the mass fraction for perfectly mixed gases. This ratio was between 1.7 and 2.5 at the first sampling location; farther downstream it approaches a constant (between 1.1 and 1.4). Sampling or calibration errors, or leaks in the preignition section may account for its difference from one. We confirmed that the changes in this ratio were due to mixing, and not to sampling effects or conversion to undetected compounds, by injecting NO instead of C2H5C1. Since NO does not react at these temperatures, its concentration at a given location reflects the mixing there. NO experiments under the low-temperature conditions agreed well with the chlorine results. Figure 3 shows normalized mole fractions of the monitored species, obtained by dividing measured mole fractions by the mixing ratio described above. In the highest-temperature case (Fig. 3a), C2H5C1 is destroyed thoroughly: none is detected 0.01 seconds after injection. Since HCI is the only chlorinated species, normalization produces a constant HCI mole fraction. CO is detected at the first few sampling locations. When the destruction of C2HnCI is less complete, a greater variety of products is observed. The medium- and low-temperature cases have destruction efficiencies of 90% and 50%. In order of abundance, the products are: HCI, CO, C2Ha, C2H3C1, and C2H2. C2HzCI is present at similar final values in the two cases, and accounts for 4.5% of the injected chlorine. Figure 4 shows the outlet levels of CzHzCI and CzHa as a fraction of the initial C2H5C1 level, plotted versus the maximum measured temperature. The highest C2H3C1 level measured was 7.6% at 1005 K. Over the range in which significant quantities are present, the ratio of C2HzCI to CzH4 increases with temperature, from 0.25 to 0.5. To test the hypothesis that the precursors of C2H3C1 were C2H4 and HCI produced from the breakdown of C~HsC1, we simultaneously injected equal quantities of HCI and CzHa. Under conditions which had produced CzHzC1 from CzHsCI, no measurable C~HzCI was observed.
898
HAZARDOUS WASTE
0.20 z H ._1
-3A CO
,.c,
0 C2HSCL
OCc;:C__C
"l-
d
-
0.15
0.10
k-= o
g
0.05
tI
x C2H4 <> C2H3CL
<}
..J o
I
1
l:iX
~0 I000 i i 0 0 1200 1300 MAXIMUM TEMPERATURE (K) FIG. 4. Normalized mole fraction CaH4 and C~H3C1 at outlet divided by normalized mole fraction C2H~CI injected, vs. maximum measured temperature.
(.~ cl .-J -6
Cb)
-3 -z
m
~
~
j
-
m
(c) mS ~
u
0 0.1 0.2 0.3 TIME FROM C2HBCL INJECTION (s) FIc. 3. Normalized measured mole fractions as a function of time after C2H5C1 injection, a) high temperature; b) intermediate temperature; c) low temperature.
(destruction efficiency 99%). Important products are HCI, CO, and C2H2, which increase in concentration throughout the simulation, and C~H4 and C~HaCI, which go through maxima. The lowesttemperature case (Fig. 5c) has a destruction efficiency of only 25%, with the same decomposition products. Although much less CzHsCI decomposes, the final C~HaCI level is higher than in the intermediate-temperature case. We have determined the most important reaction pathways in the kinetic simulation by examining the contribution of each reaction to the formation or destruction of particular species. In our mechanism, the breakdown of C2HsCI proceeds primarily through three reactions: HCI elimination and Cl radical attack forming CH2C1CHz and CHaCHC1. CaH5CI ~ C2H4 + HCI, CaH~CI + C1 ~ CH2CICH2 + HCI, CaHsCI + ~ CH3CHCI + HC1.
Numerical Modeling: Figure 5 presents some numerical modeling resuits. At high temperatures (Fig. 5a), the C~HsCI mole fraction drops abruptly to below parts per billion, and HC1 forms rapidly. CO rises abruptly and then falls gradually. A spike in the C2H4 mole fraction, attaining a value of 0.001, occurs in the first millisecond, but is indistinguishable from the y-axis in the figure. At intermediate temperatures, the destruction of C~H~CI is slower and less complete
OH radical attack is next in importance. The CHzCICHz and CHaCHC1 radicals decompose unimolecularly to form C2H4 and C2HaCI, respectively. C2H4 and C2HzC1 then react to varying degrees via radical attack. At high temperatures, conversion to CO2 is virtually complete. In the intermediate-temperature case, the bulk of the carbon is in the form of CO at the outlet, while at low temperatures carbon remains largely in the form of C2HsCI, C2H4, and C2HzCI.
THERMAL DESTRUCTION OF CzHsC1
i" i
i
"1 I
-s
I
I
Net.
_
CO
_
k _
~
-
-s
-
"--41I/-
-3~-
-
It~
899
our experiments cannot prove that these isomers are crucial to the formation of CzHaCI, we have shown experimentally that reactions of HCI and CgH4 are not the route of CgHaCI production. It appears that CHCICH3 may.be a significant species in the formation of CzHaCI, since C--CI bond fissure (producing the energetically unfavored biradical CHaCH) is not the sole decomposition route. Niedzielski et al. 19 have measured rates of formation of CHCICH3 via abstraction of H from C2H5C1 by CI atoms near room temperature; although the alpha site, containing the C--CI bond, is favored by a factor of 5 at 280 K, the ratio decreases with temperature. The distribution of CzHsC1 decomposition produets is extremely sensitive to temperature in the range studied here. Thus assumptions made in modeling the flow and temperature field of the combustor may have a substantial impact on calculated mole fractions. The considerable uncertainties in the mechanism and rates also contribute to differences between measured and calculated composition. We have not attempted to fit the modeling result to our experiments. The only changes in the mechanism were to account for the different isomers containing chlorine.
-
4_
0 0.1 0.2 0.3 TIME FROM C2HSCL INJECTION (s) FIG. 5. Calculated mole fractions as a function of time after CzHsC1 injection, a) high temperature; b) intermediate temperature; c) low temperature.
Discussion:
The observation of C2H3C1 (vinyl chloride) was unexpected, and of considerable interest because the compound is a known human carcinogen and because its synthesis could be of practical value. Its formation from C2H5C1 had been observed in an adiabatic compression/expansion system 17 but in later experiments in the absence of oxygen it was attributed to catalytic effects. 18 Our modified mechanism predicts CzHaCI formation at levels within a factor of 3 of measured values, significantly better agreement than the original mechanism, which does not distinguish between Ca chlorinated isomers. While
Conclusions In the temperature range 900-1050 K, large quantities of C2HzCI (vinyl chloride) were observed experimentally, accounting for up to 7.6% of the chlorine injected as CgHsCI. C2H5C1 does not simply decompose to C2H4 and HCI, as was expected. Our modified kinetics mechanism, which distinguishes between C2 chlorinated isomers, predicts higher levels of C2HaCI than previous available mechanisms. This significantly improves agreement with experimental results for CzHzC1. The production of C~H3C1 from CsHsCI demonstrates that it is possible to form hazardous compounds from relatively innocuous chlorinated species. Acknowledgments
We thank Murray Thomson and Karim Taga for their help with the experiment. This study benefited from conversations with Drs. Selim Senkan, David Golden, Gary Miller, William Pitz, Frank Tulley, and Charles Westbrook. This research was supported by the National Institutes of Environmental Health Sciences Superfund Research Program, grant number P42 ES047050-01. E. Fisher was supported by a scholarship from the Air and Waste Management Association.
900
HAZARDOUS WASTE REFERENCES
1. MASON, H. B., NICHOLSON, J. A., DEROSmR, R. J., AND WOLBACH, C. D.: Pilot Scale Testing of Non-steady Boiler Waste Cofiring. Paper presented at the International Symposium on Incineration of Hazardous, Municipal, and Other Wastes, American Flame Research Committee Fall Meeting, Palm Springs, CA, 1987. 2. CUNDY, V. A., LESTER, T. W., STERLING, A. M., MONTESTRUC, A. N., MORSE, J. S., LEGER, C. B., AND ACHARYA, S.: J. Air Pollut. Control Assoc. 39, 944 (1989). 3. KRAMLICH, J. C., HEAP, M. P., SEEKER, W. R., AND SAMUELSEN, G. S.: Twentieth Symposium (International) on Combustion, p. 1991, The Combustion Institute, 1985. 4. WENDT, J. O. L. AND LINAK, W. P. : Comb. Sei. Tech. 61, 169 (1988). 5. SENSER, D. W., MORSE, J. S., AND CUNDY, V. A.: Hazard. Waste and Hazardous Materials 2, 473 (1985). 6. TAYLOR, P. H. AND DELLINGER, B.: Envirn. Sci. Tech. 22, 438 (1988). 7. RrrrER, E. R., BOZZELLI, J. W., AND DEAN, A. M.: Kinetic Study on Thermal Decomposition of Chlorobenzene Diluted in Ha. to appear in J. Phys. Chem. (1990). 8. KARBA, S. B., GUTMAN, D., AND SENKAN, S. M.: Comb. Sci. Tech. 60, 45 (1988). 9. CHANG, W. D., KARRA, S. B., AND SENKAN, S. M.: Comb. Sci. Tech. 49, 107 (1986). 10. TSANG, W. : Mechanisms for the Formation and Destruction of Chlorinated Organic Products of Incomplete Combustion. Paper presented at the First International Congress on Toxic Combustion Byproducts, Los Angeles, CA, August 1989. 11. MILLER, G. P., LESTER, T. W., AND CUNDY, V.
12. 13.
14.
15.
16.
17.
18.
19.
A. : A Computational Simulation of Carbon Tetr a c h l o r i d e / M e t h a n e / A i r Flames. Paper pres e n t e d at t h e A m e r i c a n C h e m i c a l Society Meeting, Dallas, TX, April 1989. OPPELT, E. T.: J Air Pollut. Control Assoc., 37, 558 (1987). HALL, M. J., LVCAS, D., TAGA, K., AND KOSHLAND, C. P.: Measuring Chlorinated Hydrocarbons in Combustion using FTIR Spectroscopy. Paper 89-53 presented at the 1989 Fall Meeting of the Western States Section/The Combustion Institute, Livermore, CA, October 1989. LUTZ, A. E., KEE, R. J., AND MILLER, J. A.: SENKIN: A Fortran Program for Predicting Homogeneous Gas Phase Chemical Kinetics with Sensitivity Analysis. Sandia Report SAND878248, 1988. REYNOLDS, W. C.: S T A N J A N - - I n t e r a c t i v e Computer Programs for Chemical Equilibrium Analysis. Thermosciences Division, Department of Mechanical Engineering, Stanford University, 1981. FISHER, E. M., KOSHLAND, C. P., HALL, M. J., AND SAWYER, R. F.: Experimental and Numerical Study of the Thermal Destruction of Chlorinated Hydrocarbons I . - - E t h y l Chloride. Paper 89-98 presented at the 1989 Fall Meeting of the Western States Section/The Combustion Institute, Livermore, CA, October 1989. GORSHKOV, S. V., KOLBANOVSKII, Yu.A., ROZOVSKII, A.YA., AND CHERNYAK, N.YA.: Kinet. Katal. 24, 253 (1983). GORSHKOV, S. V., KOLBANOVSKII, Yu.A., RozovSKn, A.YA., AND CHERNYAK, N.YA.: Kinet. Katal. 27, 263 (1986). NIEDZaELSrd, J., TSCHUIKOW-ROux, E., AND YANO, T.: Int. J. Chem. Kinet. 16, 621 (1984).
Appendix A. Changes to the Reaction Mechanism of K a r r a et al. s Modified reaction rates (k = AT" e x p ( - E / R T ) ) (cm, cal, s, mole units) Reaction as listed originally CH2CI+CHaCI=CaH4Cla CHaCI+CHaCI=CaH4CI+C1 CzHsCI+ H = C a H 4 C l + Ha CaHsCI+CI=CaH4CI+HC1 CaHsC1 + CHa~CaH4CI + CH4 C2HsCI+CHaCI =C2H4CI+CH3CI CaHsCI+O=CaH4CI+OH
Modified reaction(s) CH2C1 + CH2C1--CH2C1CH2C1 CH2CI + CH2CI=CH2C1CHa + CI C2H5C1 + H=CHaCICH2 + Ha CaH~CI + H = C H 3 C H C 1 + Ha CaH~C1 + CI=CH2CICHa + HCI CaHsC1 + CI=CH3CHC1 + HCI CaHsCI + CH3=CHaC1CHa + CH4 CaHsC1 + C H a = C H 3 C H C I + CH4 C2H5C1 + CHaCI=CHzC1CH2 + CH3C1 CaHsCI + CHaCI=CH3CHC1 + CH3C1 CaHsC1 + O=CHaCICH2 + OH CaHsC1 + O = C H 3 C H C I + OH
A
n
E
1.100E36 1.910E17 3.000E13 2.000E13 8.460E12 5.640E12 6.000Ell 4.000Ell 1.896E12 1.264E12 4.656E13 3.104E13
- 7.200 -1.013 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
8600 9655 10000 10000 616 616 8500 8500 9000 9000 6600 6600
THERMAL DESTRUCTION O F C~HsC1
901
Appendix A, (Cont.) Modified reaction rates (k = AT" exp(-E/RT)) (cm, cal, s, mole units) Reaction as listed originally C~HsCI+OH~CzH4CI+H~O CzH4CI~CzHaCI+HCI C~H4CI~+H~CzH4CI+HC1 C~H4CI~+H~C~HaC~+ H~
C2H4CI~+CI=C~HaCI~+HCI
CzH.Ci~ + CHa=CzHaCI~ + CH~
CaH~Cla + CH~CI ~CzHaCI~ + CHaC1
CzH~Cla + O=CzHaCI2 + OH
C~H4CI~+ OH=C~HaCI2 + HzO
CzH4CI~C~H~ + CI C~H4C1 + H ~ C ~ H . + HC1 CzH4C1 + CI~C~H3C1 + HCI C~HaCI~C~HaC1 + C1 C~H3CI~ + H~C~H3CI + HCI C~HaC1 + H~C~HzCI + Hz C~HaC1 + CI~C2H~C1 + HCI C~H3C1 + CHa~CzHzCI + CH4 CzHaCI + CHIC1 ~C~HzCI + CHaCI C~HaC1 + OH~C2H~CI + H~O CgH~ + CI~C~H~C1 C~H~CI + O ~ C H C 1 0 + CHO C~H~C1 + O~C2H~O + C1
Modified reaction(s)
A
C2H5C1 + OH=CHzC1CH2 + H20 C~HsC1 + O H = C H a C H C I + HzO CHC12CHa=C~H3CI + HC1 CH2C1CH2CI=C2H3C! + HCI CH2C1CH2CI + H = C H 2 C I C H z + HC1 CHC12CHa + H=CHaCHC1 + HC1 CHC12CHa+ H=CHaCCI2 + H2 CHC12CHa+ H=CHCI~CH2+ H~ CH2C1CH2C1 + H=CH2C1CHCI+ H2 CHC12CHa + CI=CHaCCI2 + HCI CHCI~CH3 + CI=CHCIzCH2 + HCI CH2C1CH2CI + CI=CH2C1CHC1 + HC1 CHCI~CHa + C Ha=CHaCCI2 + CH4 CHCI2CHa + CHa=CHC12CH2 + CH4 CH2C1CHzC1 + CH3=CH2C1CHC1 + CH4 CHC12CH3 + CH2CI=C H3CClz + CHaCI CHCI2CH3 + CHzCI=CHCI2CHz + CH3C1 CH2C1CH2CI + CH2C1 =CH2C1CHC1 + CHaC1 CHC12CH3 + O = C HaCCI~ + OH CHC12CH3 + O = C HClzCH~ + OH CH~C1CH2CI + O=CH2C1CHC1 + OH CHC12CHa + OH=CHaCC12 + H20 CHC12CH3 + OH=CHC12CHz + H20 CH2C1CH~CI+ OH=CH~C1CHC1 + H:O CHzCICH~=CzH4 + CI CH3CHCI-~C~HaC1 + H CH~CICHz+ H=C~H4+ HC1 CH~CICH~ + CI=CzHaCI + HCI CH3CHCI + CI=C~H3C1 + HC1 CH~C1CHCI=C~HaCI + C1 CHCI~CH2=C~HaC1 + C1 CHCleCH~ + H=CzHaC1 + HC1 CH~C1CHC1 + H=C~HaC1 + HC1 C~HaC1 + H = C H C I C H + H2 C~HaC1 + H=CH~CC1 + H~ CzH3CI + CI=CHC1CH + HCI C~H3CI + CI=CH~CCI + HCI C~HaCI + C H 3 = C H C I C H + CH4 CzHaC1 + C H a = C H z C C I + CH4 CzH3CI + C H z C I = C HC1CH + CHaCI C~HaC1 + CH~CI=CH~CCI + CHaCI CzHaC1 + O H = C H C I C H + H~O CzHaC1 + OH~CH2CC1 + H~O C~H2 + C I = C H C I C H CHC1CH + O 2 = C H C 1 0 + CHO CH~CCI + O z = C H C I O + CHO CHCICH + O=C~HzO + C1 CH~CC1 + O=C2H20 + C1
3.000E13 2.000E13 6.610E13 6.610E13 6.310E13 6.310E13 1.250E13 3.750E13 5.000E13 6.275E12 1.882E13 2.510E13 2.500Ell 7.500Ell 1.000El2 7.900Ell 2.370E12 3.160E12
*This rate was chosen to be the same as the rate for C2Hs=CgH4 + H.
1.250E13 3.750E13 5.000E13 9.950E 12 2.985E13 3.980E13 1.050E20 7.000E25 3.160E12 1.000El3 1.000El3 4.950E20 4.950E20 1.000El3 1.000El3 6.667E13 3.333E13 6.667E13 3.333E13 6.667Ell 3.333Ell 6.667Ell 3.333Ell 3.333E 13 1.667E13 5.130E18 2.000E12 2.000E12 3.000E13 3.000E13
n .000 .000 -.084 -.084 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
E 4000 4000 58000 58000 8400 8400 10000 10000 10000 3100 3100 3100 8500 8500 8500 9000 9000 9000
.000 7000 .000 7000 .000 7000 .000 4000 .000 4000 .000 4000 -2.360 22000 -4.100 42984* .000 0 .000 3000 .000 3000 -2.350 20000 -2.350 20000 .000 1000 .000 1000 .000 10000 .000 10000 .000 5000 .000 5000 .000 11000 .000 11000 .000 12000 .000 12000 .000 3000 .000 3000 -2.740 -1779 .000 0 .000 0 .000 0 .000 0