The oxidation of soot and carbon monoxide in hydrocarbon diffusion flames

Journal Article · Sun May 01 04:00:00 EDT 1994 · Combustion and Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(94)90001-9· OSTI ID:7295150

Puri, R; Santoro, R J ^[1]; Smyth, K C ^[2]

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1. Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical Engineering
2. National Inst. of Standards and Technology, Gaithersburg, MD (United States). Building and Fire Research Lab.

Quantitative hydroxyl radical concentrations and primary soot particle sizes have been determined in the soot oxidation regions of axisymmetric diffusion flames burning methane, methane/butane, and methane/1-butene in air at atmospheric pressure. The total carbon flow rate was held constant in these flames while the maximum amount of soot varied by a factor of seven along the centerline. Laser-induced fluorescence measurements of OH were placed on an absolute basis by calibration against earlier absorption results. The primary size measurements of the soot particles were made using thermophoretic sampling and transmission electron microscopy. OH concentrations are greatly reduced in the presence of soot particles. Whereas large super-equilibrium ratios are observed in the high-temperature reaction zones in the absence of soot, the OH concentrations approach equilibrium values when the soot loading is high. The diminished OH concentrations are found to arise from reactions with the soot particles and only to a minor degree from lower temperatures due to soot radiation losses. Analysis of the soot oxidation rates computed from the primary particle size profiles as a function of time along the flame centerlines shows that OH is the dominant oxidizer of soot, with O[sub 2] making only a small contribution. Higher collision efficiencies of OH reactions with soot particles are found for the flames containing larger soot concentrations at lower temperatures. A comparison of the soot and CO oxidation rates shows that although CO is inherently more reactive than soot, the soot successfully competes with CO for OH and hence suppresses CO oxidation for large soot concentrations.

• OSTI ID: 7295150
• Journal Information: Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 97:2; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
025000 -- Petroleum-- Combustion
03 NATURAL GAS
034000* -- Natural Gas-- Combustion
AIR POLLUTION CONTROL
ALKANES
ALKENES
BUTANE
BUTENES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION KINETICS
CONTROL
HYDROCARBONS
KINETICS
METHANE
MONITORING
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
POLLUTION CONTROL
REACTION KINETICS
SOOT