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Full-Text Articles in Engineering
Modeling Soot Oxidation And Gasification With Bayesian Statistics, Alexander Jon Josephson, Neal D. Gaffin, Sean T. Smith, Thomas H. Fletcher, David Lignell
Modeling Soot Oxidation And Gasification With Bayesian Statistics, Alexander Jon Josephson, Neal D. Gaffin, Sean T. Smith, Thomas H. Fletcher, David Lignell
Faculty Publications
This paper presents a statistical method for model calibration using data collected from literature. The method is used to calibrate parameters for global models of soot consumption in combustion systems. This consumption is broken into two different submodels: first for oxidation where soot particles are attacked by certain oxidizing agents; second for gasification where soot particles are attacked by H2O or CO2 molecules. Rate data were collected from 19 studies in the literature and evaluated using Bayesian statistics to calibrate the model parameters. Bayesian statistics are valued in their ability to quantify uncertainty in modeling. The calibrated consumption model with …
Model Compound Study Of The Pathways For Aromatic Hydrocarbon Formation In Soot, Randall E. Winans, Nancy A. Tomczyk, Jerry E. Hunt, Mark S. Solum, Ronald J. Pugmire, Thomas H. Fletcher
Model Compound Study Of The Pathways For Aromatic Hydrocarbon Formation In Soot, Randall E. Winans, Nancy A. Tomczyk, Jerry E. Hunt, Mark S. Solum, Ronald J. Pugmire, Thomas H. Fletcher
Faculty Publications
As a follow-up of previous work on the flame pyrolysis of biphenyl and pyrene, a more detailed analysis of the pyrolytic products has been done using additional NMR data obtained on the whole soot sample correlated with detailed high-resolution and GC mass spectrometry data on the solvent-extracted portion of the same samples. These latter data complement the earlier NMR data with details of the pre-sooting structures, referred to as “young soot”, in pyrolyzed biphenyl samples collected at 1365, 1410, and 1470 K and pyrene at 1410 and 1470 K. The data reveal the roles played by free-radical-assisted polymerization reactions as …
Transformations Of Coal-Derived Soot At Elevated Temperature, Thomas H. Fletcher, Jim Rigby, Jinliang Ma, Brent W. Webb
Transformations Of Coal-Derived Soot At Elevated Temperature, Thomas H. Fletcher, Jim Rigby, Jinliang Ma, Brent W. Webb
Faculty Publications
Coal pyrolysis experiments were performed in the post-flame region of a CH4/H2/air flat-flame burner operating under fuel-rich conditions, where the temperature and gas compositions were similar to those found in the near-burner region of an industrial pulverized coal-fired furnace. Volatiles released from the coal particles formed a cloud of soot particles surrounding a centrally fed coal/char particle stream. Soot samples were collected from the cloud at different residence times using a water-cooled, nitrogen-quenched probe. The soot samples were then analyzed for their elemental compositions of carbon, hydrogen, nitrogen, sulfur, and (by difference) oxygen plus inorganic matter. …
13-C Nmr Analysis Of Soot Produced From Model Compounds And A Coal, Mark S. Solum, Adel F. Sarofim, Ronald J. Pugmire, Thomas H. Fletcher, Haifeng Zhang
13-C Nmr Analysis Of Soot Produced From Model Compounds And A Coal, Mark S. Solum, Adel F. Sarofim, Ronald J. Pugmire, Thomas H. Fletcher, Haifeng Zhang
Faculty Publications
Soot samples, including the associated organics, produced from an Illinois No. 6 coal (five samples) and two model compounds, biphenyl (three samples) and pyrene (two samples), have been studied by 13C NMR methods. The coal soot data served as a guide to selection of the temperature range that would be most fruitful for investigation of the evolution of aerosols composed of soot and tars that are generated from model compounds. The evolution of the different materials in the gas phase followed different paths. The coal derived soots exhibited loss of aliphatic and oxygen functional groups prior to significant growth …
Small-Angle X-Ray Studies Of Soot Inception And Growth, Jan P. Hessler, Soenke Seifert, Randall E. Winans, Thomas H. Fletcher
Small-Angle X-Ray Studies Of Soot Inception And Growth, Jan P. Hessler, Soenke Seifert, Randall E. Winans, Thomas H. Fletcher
Faculty Publications
The high spectral intensity of X-rays produced by the undulator at the Basic Energy Sciences Synchrotron Radiation Center of Argonne's Advanced Photon Source has allowed us to perform small-angle X-ray scattering (SAXS) studies of the initial distribution of soot particles formed by various fuels. SAXS provides an in situ probe of the morphology of soot in the region between 1 and 100 nm and complements the ex situ technique of electron microscopy. The basic aspects of SAXS and its potential are illustrated with measurement on a laminar flame of acetylene in air. The more complex fuel toluene has been studied …
Measurement Of Soot And Char In Pulverized Coal Fly Ash, John M. Veranth, Thomas H. Fletcher, David W. Pershing, Adel F. Sarofim
Measurement Of Soot And Char In Pulverized Coal Fly Ash, John M. Veranth, Thomas H. Fletcher, David W. Pershing, Adel F. Sarofim
Faculty Publications
The unburned carbon in the fly ash produced by low-NOx pulverized coal combustion has been shown by electron microscopy to be a mixture of porous coal char particles and aggregates of submicron particles, which are thought to be soot. The carbon is bimodally distributed with large soot aggregates mixed with the char in the particles larger than 10 microns and dispersed soot found with the submicron particles. A method for determining the mass of soot and char by liquid-suspension gravity separation was used with both laboratory-scale and power plant fly ash samples. For low-NOx, staged, pilot-scale combustion of bituminous coal …
Modeling Soot Derived From Pulverized Coal, Alexander L. Brown, Thomas H. Fletcher
Modeling Soot Derived From Pulverized Coal, Alexander L. Brown, Thomas H. Fletcher
Faculty Publications
A semiempirical model has been developed for predicting coal-derived soot. The main feature of the model is a transport equation for soot mass fraction. Tar prediction options include either an empirical or a transport equation approach, which directly impacts the source term for soot formation. Also, the number of soot particles per unit mass of gas may be calculated using either a transport equation or an assumed average. Kinetics are based on Arrhenius rates taken from published measurements. Radiative properties are calculated as a function of averaged optical constants, predicted gas temperatures, predicted gas densities, and the soot mass fractions. …
Soot In Coal Combustion Systems, Thomas H. Fletcher, Jinliang Ma, Jim Rigby, Alexander L. Brown, Brent W. Webb
Soot In Coal Combustion Systems, Thomas H. Fletcher, Jinliang Ma, Jim Rigby, Alexander L. Brown, Brent W. Webb
Faculty Publications
Soot is generated from coal when volatile matter, tar in particular, undergoes secondary reactions at high temperatures. A description of soot in coal flames allows better calculations of radiative transfer and temperatures in near-burner regions, which in turn allows more accurate predictions of NOx formation in coal-fired furnaces. Experiments are reviewed that examine the formation, agglomeration and properties of coal-derived soot, including pyrolysis experiments and combustion experiments. This review includes the types of experiments performed, the soot yields obtained, the size of the soot particles and agglomerates, the optical properties of soot, the relationship between coal-derived soot and soot …
Conversion Of Coal Tar To Soot During Coal Pyrolysis In A Post-Flame Environment, Thomas H. Fletcher, Jinliang Ma, Brent W. Webb
Conversion Of Coal Tar To Soot During Coal Pyrolysis In A Post-Flame Environment, Thomas H. Fletcher, Jinliang Ma, Brent W. Webb
Faculty Publications
Coal pyrolysis experiments were performed in the postflame region of a CH4/H2/air flat-flame burner operating under fuel-rich conditions, where the temperature and gas compositions were similar to those in the near-burner region of a large-scale coal-fired furnace. Volatiles released from the coal particles formed a cloud of soot particles at high temperatures in the absence of oxygen. The soot particles in the cloud were collected at different residence times using a water-cooled, nitrogen-quenched suction probe. Test variables included the reaction temperature and coal type. Soot yields in terms of weight percentage of dry ash-free coal were measured based on bulk …
Thermophoretic Sampling Of Coal-Derived Soot Particles During Devolatilization, Jinliang Ma, Thomas H. Fletcher, Brent W. Webb
Thermophoretic Sampling Of Coal-Derived Soot Particles During Devolatilization, Jinliang Ma, Thomas H. Fletcher, Brent W. Webb
Faculty Publications
Thermophoretic sampling of soot particles formed during high-temperature coal devolatilization is performed in order to examine soot particle sizes and shapes. Coal particles are injected along the centerline of a laminar flow flat flame burner, where a fuel-rich methane-air flame is used as a heat source. Volatiles released from the coal particles form a cloud of soot particles at high temperatures in the absence of oxygen. A carbon-coated microscope grid is briefly inserted into the soot cloud, where the temperature gradient between the soot particles and the cold grid surface causes the migration of soot particles and results in deposition. …