Elementary, pressure dependent model for combustion of C1, C2 and nitrogen containing hydrocarbons : operation of a pilot scale incinerator and model comparison
Department of Chemical Engineering, Chemistry and Environmental Science
Doctor of Philosophy
Bozzelli, Joseph W.
Barat, Robert Benedict
Krasnoperov, Lev N.
Grenda, Jeffrey M.
C1 C2 hydrocarbon
A 140000 BTU/hr pilot scale incinerator has been constructed, tested and run; and an online sampling train capable of taking in situ data has been established. The continuous on-line analytical instruments include a CO analyzer, an NO/NOx analyzer and an 02 analyzer. In addition, two gas chromatographs with flame ionization detector are used to determine CH4, C2H2 + C2H4 and total hydrocarbon concentrations. Typical operating conditions are at an average 02 concentration of 6 - 8 %. The NO concentration ranged from 100 - 200 ppm. Approximately I ppm of CH.4 is also present at steady state operations.
The kinetic model for the combustion process in the pilot scale incinerator consists of elementary reaction kinetics for oxidation of the model fuel species: CH4, CH3OH, C2H2, C2H4, C2H6 and CH3NH2. Thermodynamic properties for these species are determine by ab initio methods and density functional theory. High-pressure limit rate constants are determine by either canonical transition state theory or variational transition states theory. In some cases, estimation techniques based on Evans-Polvani relationships are used. Pressure and temperature dependent mechanism is constructed utilizing QRRK for k(E) with either master equation or modified strong collision analysis for fall-off The mechanism is constructed over the pressure range of 0. 00 1 - 100 atm and over a temperature range of 300 - 2500 K.
A reactor configuration of an isothermal perfectly stirred reactor (PSR) followed by a plugged flow reactor with heat transfer loss (PFRI), followed by a second plugged flow reactor with a different heat transfer loss (PFR2) is used to model the pilot scale incinerator. Concentration profiles are determined from the detailed kinetic model based on the reactor configuration. Results show that02, is consumed and CO2 and NO are formed mainly in the PSR. The concentration of these three components do not change throughout PFRI and PFR2. Comparison of the NO and NOx experimental data with the model shows the data are in the same range, varying from 100 - 200 ppm, with less than 50 pprn difference. The average NO:NOx ratio for experimental data is 0.97, and the average NO'NOx ratio from the model results is 0.98.
njit-etd2002-019 (451 pages ~ 18,165 KB pdf)
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Created March 18, 2003