Inverse co-flow approach to sooting laminar diffusion flames
Normal and inverse diffusion flames (NDFs and IDFs) were used to study flame pyrolysis and soot formation processes. In an IDF, the reactant flows are reversed from the NDF configuration, that is, the oxidizer flows through the central tube into a surrounding co-flowing fuel stream. Soot formation processes are more effectively separated from oxidation processes in the IDF, which also tend to soot less. Temperature-controlled smoke height tests were applied to allene, 1,3-butadiene, several cyclic hydrocarbons, and branched aliphatic fuels. As found in previous studies, pyrolysis chemistry governs soot formation. Thermocouples and microprobe sampling were then used to measure thermal and chemical fields of NDF and IDF pyrolysis zones. First, NDF pyrolysis zones were probed using fuels with high sooting tendency, namely allene, 1,3-butadiene and benzene. The results support the growing consensus that aromatic ring formation is a controlling step in soot formation. The particular aromatic formation mechanism depends on flame type, fuel structure and local temperature. Next, the transition from near to slightly-sooting IDFs was examined using methane, ethene, propene and 1-butene as fuels. Soot inception occurred for the olefins when: (1) the temperature exceeded approximately 1300K in a predominantly pyrolytic regions; and (2) the location was sufficiently close to the main oxidation zone (where radicals are generated). Methane required higher temperatures to induce inception because it does not readily form acetylene. While these conditions determine whether inception will occur, the aromatic content, which scaled with the fuel's sooting tendency, affects the ultimate soot loading once inception has occurred.
- Research Organization:
- Princeton Univ., NJ (USA)
- OSTI ID:
- 5717783
- Country of Publication:
- United States
- Language:
- English
Similar Records
Structure of laminar sooting inverse diffusion flames
Oxidation/pyrolysis chemistry as related to fuel-sooting tendencies
Related Subjects
025000* -- Petroleum-- Combustion
03 NATURAL GAS
034000 -- Natural Gas-- Combustion
AEROSOLS
ALKANES
ALKENES
ALLENE
AROMATICS
BENZENE
BUTADIENE
BUTENES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COLLOIDS
COMBUSTION KINETICS
CORRELATIONS
DECOMPOSITION
DIENES
DIFFUSION
DIMENSIONS
DISPERSIONS
ETHYLENE
FLAME PROPAGATION
FLAMES
HEIGHT
HYDROCARBONS
KINETICS
METHANE
ORGANIC COMPOUNDS
OXIDATION
POLYENES
PROPYLENE
PYROLYSIS
REACTION KINETICS
RESIDUES
SAMPLING
SMOKES
SOLS
SOOT
SYNTHESIS
TEMPERATURE DEPENDENCE
THERMOCHEMICAL PROCESSES