Soot formation from polycyclic aromatics. Final report, September 1, 1980-August 31, 1982
Knowledge of the mechanism of soot formation and the ability to predict the soot yield under various conditions is of great importance to combustor design. The present work for the first time, offers a consistent approach to empirical modeling of soot formation during the pyrolysis of aromatic hydrocarbons. Understanding and adequate modeling of the pyrolysis of aromatic hydrocarbons are necessary steps towards the prediction of sooting in flames. Soot formation in toluene-argon mixtures has been investigated behind reflected shock waves by monitoring attenuation of a laser beam in the visible (632.8 nm) and the infrared (3.39 ..mu..m) regions of the spectrum. The experimental data indicated a strong pressure effect on soot formation which cannot be rationalized within Graham's model. A new model for soot formation was proposed that not only explains the observed phenomena but also unifies the various experimental facts which previously had been considered to be contradictory. The size of soot particles formed during the shock-tube pyrolysis of toluene was measured by laser Doppler velocimetry. The particle size appeared to be of the order of a micron. This result indicates that: (a) agglomeration of the primary soot spheres takes place prior to the onset of cooling, and (b) the use of the Rayleigh limit of the Mie scattering theory for the determination of absolute soot yield is invalid and leads to an over-estimation of the conversion of hydrocarbon to soot. During the pyrolysis of acetylene-, allene-, and 1,3-butadiene-argon mixtures, a bell-shaped dependence of soot yield on temperature was observed for all three compounds similar to that previously reported for toluene. The results show that soot is formed much faster and in much larger quantities from allene than from 1,3-butadiene.
- Research Organization:
- Louisiana State Univ., Baton Rouge (USA). Dept. of Chemical Engineering
- DOE Contract Number:
- FG22-80PC30247
- OSTI ID:
- 6263480
- Report Number(s):
- DOE/PC/30247-T4; ON: DE83009750
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ACETYLENE
ALKYNES
ALLENE
ARGON
AROMATICS
BUTADIENE
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DECOMPOSITION
DIENES
ELEMENTS
FLUIDS
GASES
HYDROCARBONS
KINETICS
MATHEMATICAL MODELS
NONMETALS
ORGANIC COMPOUNDS
PARTICLE SIZE
POLYCYCLIC AROMATIC HYDROCARBONS
POLYENES
PRESSURE DEPENDENCE
PYROLYSIS
RARE GASES
REACTION KINETICS
SIZE
SOOT
SYNTHESIS
TEMPERATURE DEPENDENCE
THERMOCHEMICAL PROCESSES
TOLUENE