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Articles 661 - 690 of 757

Full-Text Articles in Chemical Engineering

Biofilm Removal Using Bubbles And Sound, Michael R. Parini Jul 2005

Biofilm Removal Using Bubbles And Sound, Michael R. Parini

Theses and Dissertations

Bacteria in biofilms adhere well to surfaces and are quite difficult to remove. Oral plaque is one example of a biofilm. Many researchers have studied ways to remove plaque and bacteria from surfaces. It has been found that the passage of a bubble across a surface to which bacteria has adhered can remove the bacteria from the surface. Biofilms of Streptococcus mutans were grown on glass coverslips as a simple model for oral plaque. The coverslips were mounted in a Plexiglas chamber filled with artificial saliva. A bubble stream was directed at the mounted biofilm. The velocity, gas fraction, median …

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Biomass-Coal Co-Combustion: Opportunity For Affordable Renewable Energy, Larry Lin Baxter Jul 2005

Biomass-Coal Co-Combustion: Opportunity For Affordable Renewable Energy, Larry Lin Baxter

Faculty Publications

This investigation explores the reasons for and technical challenges associated with co-combustion of biomass and coal in boilers designed for coal (mainly pulverized coal) combustion. Biomass-coal co-combustion represents a near-term, low-risk, low-cost, sustainable, renewable energy option that promises reduction in net CO2 emissions, reduction in SOx and often NOx emissions, and several societal benefits. Technical issues associated with cofiring include fuel supply, handling and storage challenges, potential increases in corrosion, decreases in overall efficiency, ash deposition issues, pollutant emissions, carbon burnout, impacts on ash marketing, impacts on SCR performance, and overall economics. Each of these issues has been investigated and …

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Autologous Fibrinogen Purification And Concentration For Use In Fibrin Sealant, Steven M. Alston Jun 2005

Autologous Fibrinogen Purification And Concentration For Use In Fibrin Sealant, Steven M. Alston

Theses and Dissertations

Fibrinogen concentrates are used widely as a sealant during and after surgery to reduce blood loss. Commercially available fibrin sealants are made from pooled human blood, which carries the risk of blood-borne diseases, and are expensive. These concerns have brought to focus the need for autologous fibrinogen concentrates. This need has been addressed by utilizing a unique approach in which fibrinogen is precipitated from plasma with protamine. The physical properties of fibrin sealant prepared from fibrinogen precipitated with protamine were evaluated. The optimal precipitation conditions included a plasma protamine concentration of 10 mg/mL at room temperature. Under these conditions 96% …

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The Effect Of Reactor Configuration On No Conversion And Energy Consumption In Non-Thermal Plasma Parallel Tube Reactors, Morris D. Argyle, Gui-Bing Zhao, S.V.B. Janardhan Garikipati, Xudong Hu, Maciej Radosz Jun 2005

The Effect Of Reactor Configuration On No Conversion And Energy Consumption In Non-Thermal Plasma Parallel Tube Reactors, Morris D. Argyle, Gui-Bing Zhao, S.V.B. Janardhan Garikipati, Xudong Hu, Maciej Radosz

Faculty Publications

This work shows that the configuration of a pulsed corona discharge reactor strongly affects the rate of electron collision reactions. Experiments involving the decomposition of NO in N2 were performed in a reactor in which the number or parallel reactor tubes varied from 1 to 10 at a constant pressure of 147.6 kPa and ambient temperature. A previously developed lumped model of the reactions accurately predicted the effects of varying the initial concentrations of NO (from 240ppm to 593ppm) and gas residence time (from 1.93 to 742 s). With an increasing number of parallel reactor tubes, the rate of the …

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The Effect Of Oxygen On Nonthermal-Plasma Reactions Of Nitrogen Oxides In Nitrogen, Morris D. Argyle, Gui-Bing Zhao, S.V.B. Janardhan Garikipati, Xudong Hu, Maciej Radosz Jun 2005

The Effect Of Oxygen On Nonthermal-Plasma Reactions Of Nitrogen Oxides In Nitrogen, Morris D. Argyle, Gui-Bing Zhao, S.V.B. Janardhan Garikipati, Xudong Hu, Maciej Radosz

Faculty Publications

NO is mainly converted to NO2 by chemical oxidation in the presence of oxygen. Initial selectivity analysis shows that three electron collision reactions are important for NOX evolution in O2/N2. The rate constants of these reactions decrease with increasing oxygen concentration. This is because oxygen is electronegative and hence reduces the electron concentration. The rate constant of O2 dissociation by electron collision reaction is almost two orders of magnitude higher than that of N2 dissociation. NO formation occurs predominantly through N(2D) + O2 → NO + O. The critical oxygen concentration, defined as the concentration above which the NOX formation …

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Stable Polymer Micelle Systems As Anti-Cancer Drug Delivery Carriers, Yi Zeng Jun 2005

Stable Polymer Micelle Systems As Anti-Cancer Drug Delivery Carriers, Yi Zeng

Theses and Dissertations

Several temporarily stable polymer micelle systems that might be used as ultrasonic-activated drug delivery carriers were synthesized and investigated. These polymeric micelle systems were Plurogel®, Tetronic®, poly(ethylene oxide)-b-poly(N-isopropylacrylamide) and poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate-lactaten). In previous work in our lab, Pruitt et al. developed a stabilized drug carrier named Plurogel® [5, 6]. Unfortunately, the rate of the successful Plurogel® synthesis was only about 30% by simply following Pruitt's process. In this work, this rate was improved to 60% by combining the process of adding 0.15 M NaCl and/or 10 µl/ml n-butanol and by preheating the solution before polymerization. Tetronics® were proved not …

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Effects Of Moisture On Combustion Characteristics Of Live California Chaparral And Utah Foliage, Steven G. Smith May 2005

Effects Of Moisture On Combustion Characteristics Of Live California Chaparral And Utah Foliage, Steven G. Smith

Theses and Dissertations

Current fire-spread models are based largely on empirical correlations based on fires burning through dead pine needles. There is a need to increase the accuracy of modeling wildfires in live vegetation. This project investigates the quantitative and qualitative ignition characteristics of eight live fuels, four from southern California (manzanita, scrub oak, ceanothus, and chamise) and four from Utah (canyon maple, gambel oak, big sagebrush, and Utah juniper). Individual leaves were observed as they were exposed to hot gases from a flat flame burner. The broadleaf species from both California and Utah had noticeable surface changes during the ignition process. All …

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Design And Performance Of A Thin-Film Calorimeter For Quantitative Characterization Of Photopolymerizable Systems, Todd M. Roper, C. Allan Guymon, Charles E. Hoyle Apr 2005

Design And Performance Of A Thin-Film Calorimeter For Quantitative Characterization Of Photopolymerizable Systems, Todd M. Roper, C. Allan Guymon, Charles E. Hoyle

Faculty Publications

A thin-film calorimeter (TFC) was designed for the quantitative characterization of photopolymerizable systems. A detailed description of its construction indicates the ease with which a TFC can be assembled and the flexibility inherent in its design. The mechanics of operation were optimized to yield a significantly faster instrument response time than other calorimetric methods such as photodifferential scanning calorimetry (photo-DSC). The TFC has enhanced sensitivity, more than an order of magnitude greater linear response range to changes in light intensity than that of the photo-DSC, resulting in the ability to measure both smaller and larger signals more accurately. The photopolymerization …

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Comprehensive Black Liquor Droplet Combustion Studies, Leong-Teng Ip Jan 2005

Comprehensive Black Liquor Droplet Combustion Studies, Leong-Teng Ip

Theses and Dissertations

Black liquor, a byproduct from pulp production, is burned in a recovery boiler to generate electricity and recover inorganic materials. Black-liquor-droplet combustion is fundamental to understanding and potentially improving recovery boiler performance. This investigation reports comprehensive experimental data collected for a suite of five liquors. All the data were collected with newly-designed laboratory equipment, several aspects of which are unique. Single droplets were suspended on a thermocouple and heated in a furnace. Simultaneous diameter (size and shape), internal and surface temperatures, surface emissivity, and mass were measured under various furnace temperatures and gas compositions. The images recorded by the cameras …

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Effects Of Pressure On Coal Pyrolysis And Char Morphology, Dong Zeng, Thomas H. Fletcher Jan 2005

Effects Of Pressure On Coal Pyrolysis And Char Morphology, Dong Zeng, Thomas H. Fletcher

Faculty Publications

A better understanding of high-pressure coal pyrolysis is needed to design advanced coal gasification combined-cycle systems. High-temperature, high-heating-rate, and high-pressure pyrolysis experiments were conducted on three bituminous coals and a lignite, to more fully understand the effects of pressure on resultant char properties. A flat-flame burner was designed and used inside a high-pressure drop-tube reactor to provide a high-temperature, high-heatingrate environment that is representative of industrial processes. Chars were prepared at four different pressures, ranging from 0.85 atm to 15 atm. The measured total volatiles yields compared well with predictions of the Chemical Percolation Devolatilization (CPD) model. The physical properties …

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Swelling Properties And Intrinsic Reactivities Of Coal Chars Produced At Elevated Pressures And High Heating Rates, Dong Zeng, Michael Clark, Todd Gunderson, William C. Hecker, Thomas H. Fletcher Jan 2005

Swelling Properties And Intrinsic Reactivities Of Coal Chars Produced At Elevated Pressures And High Heating Rates, Dong Zeng, Michael Clark, Todd Gunderson, William C. Hecker, Thomas H. Fletcher

Faculty Publications

A high-temperature, high-pressure flat-flame burner reactor was developed to prepare char at different pressures. This system achieves particle heating rates of 105 K/s, which better mimics industrial conditions than conventional drop tube or radiative flow reactors. Previous data at atmospheric pressure demonstrated a significant decrease in particle swelling during devolatilization as heating rates increased from 104 K/s (the typical drop tube heating rate) to 105 K/s. Pyrolysis experiments were performed at pressures from 1 to 15 atm at 1300 C for two bituminous coals and a lignite. Average swelling was determined from a combination of the mass …

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Polymerization Kinetics Of Peo-B-Pnipaam Block Copolymers, William G. Pitt, Yi Zeng Jan 2005

Polymerization Kinetics Of Peo-B-Pnipaam Block Copolymers, William G. Pitt, Yi Zeng

Faculty Publications

Our research in ultrasonic activated drug delivery motivated us to develop polymeric micelles that sequester hydrophobic drugs (Fig. 1) until they are sheared open by cavitation events produced by low frequency ultrasound (Fig. 2). [1] Using this type of drug delivery system, micelles sequestering drug can circulate freely without releasing their drug until they flow through a tumor or other tissue insonated by low frequency ultrasound. There they release part of their drug (Fig. 3). [2,3] This drug delivery technology was used to reduce tumors in a rat model [4] using block copolymers of PEO and PPO. However, we are …

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Mechanism Of Targeted Chemotherapeutic Delivery Using Ultrasound, Thaidra A. Gaufin, Byron K. Murray, Seiga Ohmine, Kim L. O'Neill, William G. Pitt, Briant S. Stringham Jan 2005

Mechanism Of Targeted Chemotherapeutic Delivery Using Ultrasound, Thaidra A. Gaufin, Byron K. Murray, Seiga Ohmine, Kim L. O'Neill, William G. Pitt, Briant S. Stringham

Faculty Publications

Ultrasound (US) is used to enhance and target delivery of drugs and genes to cancer tissues. The advantages of focused delivery to select tissues are manifold, but the exact mechanisms are largely unknown and need clarification to optimize delivery. The present study further defined the role of collapse cavitation in US-induced permeabilization of cell membranes and subsequent drug or gene uptake by the cell. Cavitation, defined as the collapse of micro-bubbles, produces high shear stresses and shock waves that may transiently puncture cell membranes and has been suggested as the cause of increased permeability. The hypothesis that collapsing bubbles permeabilize …

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Observations Of Flame Behavior In A Laboratory-Scale Premixed Natural Gas/Air Gas Turbine Combustor From Planar Laser Induced Fluorescence Measurements Of Oh, Laser Doppler Anemometer Velocity Measurements, And Coherent Anti-Stokes Roman Spectrometer Temperature Measurements, Thomas H. Fletcher Jan 2005

Observations Of Flame Behavior In A Laboratory-Scale Premixed Natural Gas/Air Gas Turbine Combustor From Planar Laser Induced Fluorescence Measurements Of Oh, Laser Doppler Anemometer Velocity Measurements, And Coherent Anti-Stokes Roman Spectrometer Temperature Measurements, Thomas H. Fletcher

Faculty Publications

Instantaneous planar laser induced fluorescence (PLIF) images of OH, simultaneous axial/radial and axial/tangential velocity measurements with an LDA (laser Doppler anemometer), and instantaneous gas temperature measurements using a coherent anti- Stokes Raman spectrometer (CARS) were obtained in a pre-mixed, swirl-stabilized laboratory-scale combustor, fired with natural gas. Four operating conditions were examined (two swirl conditions and equivalence ratios of 0.80 and 0.65). The instantaneous PLIF images of OH illustrate the chaotic nature of the turbulent flame eddies. Mean and standard deviations of each variable were measured at different locations in the flame, along with probability density functions. Stability of the flame …

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Simulated Land-Based Turbine Deposits Generated In An Accelerated Deposition Facility, Jared W. Jensen, Sean W. Squire, Jeffrey P. Bons, Thomas H. Fletcher Jan 2005

Simulated Land-Based Turbine Deposits Generated In An Accelerated Deposition Facility, Jared W. Jensen, Sean W. Squire, Jeffrey P. Bons, Thomas H. Fletcher

Faculty Publications

This report presents a validation of the design and operation of an accelerated testing facility for the study of foreign deposit layers typical to the operation of land-based gas turbines. This facility was designed to produce turbine deposits in a 4-h test that would simulate 10,000 h of turbine operation. This is accomplished by matching the net foreign particulate throughput of an actual gas turbine. Flow Mach number, temperature and particulate impingement angle are also matched. Validation tests were conducted to model the ingestion of foreign particulate typically found in the urban environment. The majority of this particulate is ceramic …

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A Finite Element Simulation Of Temperature And Material Flow In Fricton Stir Welding, Mark J. Lasley Dec 2004

A Finite Element Simulation Of Temperature And Material Flow In Fricton Stir Welding, Mark J. Lasley

Theses and Dissertations

The purpose of this research was to use the Transvalor S.A. product, Forge3, to develop a finite element simulation of the friction stir welding process that improves the predictability of temperature evolution and material flow within the plunge portion of the process. Previous modeling created more heating within the billet than experimental results, probably due to the simplification of the simulation with adiabatic boundary conditions. More realistic tooling temperatures were included in this model as these affect heat evolution which is a determining factor in microcrystalline growth. These results were validated by experimental efforts using a billet and tooling instrumented …

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The Effect Of Gas Pressure On No Conversion Energy Efficiency In Nonthermal Nitrogen Plasma, Morris D. Argyle, Gui-Bing Zhao, S.V.B. Janardhan Garikipati, Xudong Hu, Maciej Radosz Nov 2004

The Effect Of Gas Pressure On No Conversion Energy Efficiency In Nonthermal Nitrogen Plasma, Morris D. Argyle, Gui-Bing Zhao, S.V.B. Janardhan Garikipati, Xudong Hu, Maciej Radosz

Faculty Publications

This work explores the effect of gas pressure on the rate of electron collision reactions and energy consumption for NO conversion in N2 in a pulsed corona discharge reactor. A previous study showed that the rate constant of electron collision reactions, multiplied by the electron concentration, can be expressed as k[e] = βα−0.5P−0.5W0.75exp(−αP/W). The model parameter α remains constant with increasing gas pressure, which verifies the previous assumption that the electron temperature is inversely proportional to gas pressure. However, the model parameter β decreases with increasing gas pressure, which indicates that the rate constant of electron collision reactions decreases with …

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Molecular-Dynamics Simulation Of The Effect Of Ions On A Liquid–Liquid Interface For A Partially Miscible Mixture, Richard L. Rowley, Kent E. Wardle, Eric Carlson, Douglas Henderson Apr 2004

Molecular-Dynamics Simulation Of The Effect Of Ions On A Liquid–Liquid Interface For A Partially Miscible Mixture, Richard L. Rowley, Kent E. Wardle, Eric Carlson, Douglas Henderson

Faculty Publications

Molecular-dynamics simulations were performed to model the effect of added salt ions on the liquid-liquid interface in a partially miscible system. Simulations of the interface between saturated phases of a model 1-hexanol + water system show a bilayer structure of 1-hexanol molecules at the interface with OH heads of the first layer directed into the water phase and the opposite orientation for the second layer. The alignment of the polar OH groups at the interface stabilizes a charge separation of sodium and chloride ions when salt is introduced into the aqueous phase, producing an electrical double layer. Chloride ions aggregate …

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Modeling The Direct Solar Conversion Of Co2 To Co And O2, Thomas H. Fletcher Jan 2004

Modeling The Direct Solar Conversion Of Co2 To Co And O2, Thomas H. Fletcher

Faculty Publications

At high temperatures (greater than 2300 K), CO2 is known to dissociate to CO and O. A prototype solar collector was previously demonstrated to achieve such high temperatures, achieving 4-6 mol % CO in the product stream from an inlet stream of pure CO2. This paper describes the results of computer modeling performed to determine the flow, temperature, and reactions occurring in the prototype device. Of particular interest are the heat-transfer and reaction mechanisms involved and how much photolysis occurs in the prototype. Predictions were performed with two different computational fluid dynamic codes (Fluent and PCGC-3). The …

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Ignition Behavior Of Live California Chaparral Leaves, Joshua D. Engstrom, Jared K. Butler, Steven G. Smith, Larry L. Baxter, Thomas H. Fletcher, David R. Weise Jan 2004

Ignition Behavior Of Live California Chaparral Leaves, Joshua D. Engstrom, Jared K. Butler, Steven G. Smith, Larry L. Baxter, Thomas H. Fletcher, David R. Weise

Faculty Publications

Current forest fire models are largely empirical correlations based on data from beds of dead vegetation. Improvement in model capabilities is sought by developing models of the combustion of live fuels. A facility was developed to determine the combustion behavior of small samples of live fuels, consisting of a flat-flame burner on a moveable platform. Qualitative and quantitative combustion data are presented for representative samples of California chaparral: manzanita (Arctostaphylos parryana); oak (Quercus berberidifolia); ceanothus (Ceanothus crassifolius), and chamise (Adenostoma fasciculatum). Times to ignition were significantly influenced by shape effects, whereas ignition temperature was more dependent on chemical composition

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Rotational Molding Of Acrylonitrile-Butadiene-Styrene Polymers And Blends, Mark Grant Spencer Dec 2003

Rotational Molding Of Acrylonitrile-Butadiene-Styrene Polymers And Blends, Mark Grant Spencer

Theses and Dissertations

The development of acrylonitrile-butadiene-styrene (ABS) resins for use in rotational molding would provide a medium performance material, thus opening doors to new markets for the rotational molding industry. Unfortunately, ABS resins have shown serious problems during the rotational molding process, namely discoloration, bridging, and poor impact strength. It is believed that these effects are due to degradation of the carbon-carbon double bond in the butadiene, through attack by either oxygen or heat. Previous efforts have shown some success in addressing these issues. However, additional improvements are necessary to make ABS resins commercially viable to rotational molders. This study, fourth in …

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Thermodynamic Property Prediction For Solid Organic Compounds Based On Molecular Structure, Benjamin T. Goodman Nov 2003

Thermodynamic Property Prediction For Solid Organic Compounds Based On Molecular Structure, Benjamin T. Goodman

Theses and Dissertations

A knowledge of thermophysical properties is necessary for the design of all process units. Reliable property prediction methods are essential because reliable experimental data are often not available due to concerns about measurement difficulty, cost, scarcity, safety, or environment. In particular, there is a lack of prediction methods for solid properties. Predicted property values can also be used to fill holes in property databases to understand more fully compound characteristics. This work is a comprehensive analysis of the prediction methods available for five commonly needed solid properties. Where satisfactory methods are available, recommendations are made; where methods are unsatisfactory in …

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In Situ Uv-Visible Assessment Of Extent Of Reduction During Oxidation Reactions On Oxide Catalysts, Morris D. Argyle, Kaidong Chen, Carlo Resini, Catherine Krebs, Alexis T. Bell, Enrique Iglesia Jun 2003

In Situ Uv-Visible Assessment Of Extent Of Reduction During Oxidation Reactions On Oxide Catalysts, Morris D. Argyle, Kaidong Chen, Carlo Resini, Catherine Krebs, Alexis T. Bell, Enrique Iglesia

Faculty Publications

The extent of reduction of active centers during oxidative alkane dehydrogenation on VOx/Al2O3 was measured from pre-edge UV-visible spectral features and found to increase with increasing VOx domain size and propane/O2 ratio.

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Effects Of Solvent Model Flexibility On Aqueous Electrolyte Behavior Between Electrodes, Richard L. Rowley, John N. Harb, Clint G. Guymon, Matthew L. Hunsaker, Douglas Henderson Jun 2003

Effects Of Solvent Model Flexibility On Aqueous Electrolyte Behavior Between Electrodes, Richard L. Rowley, John N. Harb, Clint G. Guymon, Matthew L. Hunsaker, Douglas Henderson

Faculty Publications

Molecular dynamics simulations have been carried out for aqueous electrolyte solutions between model electrode surfaces. The effect of solvent model flexibility on bult and double layer properties was observed for electrode surface charge densities of 0, 0.1 and 0.2 and ion concentrations of 0, 0.5 and 1 M. Two flexible models were used to isolate the effects of flexibility from the effects of a change in the condensed-phase dipole moment. Model flexibility increases the pure water self-diffusion coefficient while a larger liquid diple moment substantially decreases it. There is an increase in ion contact adsorption and counter ion affinity with …

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Interaction Energy Surfaces Of Small Hydrocarbon Molecules, Richard L. Rowley, Jukka-Pekka Jalkanen, Tapani A. Pakkanen, Yan Yang Mar 2003

Interaction Energy Surfaces Of Small Hydrocarbon Molecules, Richard L. Rowley, Jukka-Pekka Jalkanen, Tapani A. Pakkanen, Yan Yang

Faculty Publications

Nonbonding interactions of small alkane molecules were studied with ab initio methods. Previously reported energy data for ethane and propane dimers were supplemented with 1747 new configurations of dimers involving slightly larger hydrocarbons. The completed work provides interaction energy surfaces for all combinations of dimer pairs involving ethane, propane, isobutane, and neopentane and thus contains information of all chemical groups found in acyclic alkanes. The strongest attraction of the studied molecule pairs was encountered in isobutane C2h dimer, where an energy minimum of -1.784 kcal mol^-1 at 4.28 Angstroms separation of centermost carbon atoms was observed. The composite data set …

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Density Of States Simulations Of Proteins, Nitin Rathore, Thomas A. Knotts Iv, Juan J. De Pablo Mar 2003

Density Of States Simulations Of Proteins, Nitin Rathore, Thomas A. Knotts Iv, Juan J. De Pablo

Faculty Publications

A modified version of a recently introduced algorithm that calculates density of states by performing a random walk in energy space has been proposed and implemented to study protein folding in a continuum. A united atom representation and the CHARMM19 [B. R. Brooks, R. E. Bruccoleri, B. D. Olafson, D. J. States, S. Swaminathan, and M. Karplus, J. Comput. Chem. 4, 187 (1983)] force field are employed for these simulations. This method permits estimation of the density of states of a protein via a random walk in the energy space, thereby allowing the system to escape from local free-energy minima …

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Fuel Characteristics Of Processed, High-Fiber Sugarcane, Scott Q. Turn, Charles M. Kinoshita, Lee A. Jakeway, Bryan M. Jenkins, Larry Lin Baxter 8507091, Ben C. Wu, Linda G. Blevins Feb 2003

Fuel Characteristics Of Processed, High-Fiber Sugarcane, Scott Q. Turn, Charles M. Kinoshita, Lee A. Jakeway, Bryan M. Jenkins, Larry Lin Baxter 8507091, Ben C. Wu, Linda G. Blevins

Faculty Publications

A study of treatment methods to improve the fuel characteristics of sugarcane variety B52298 was conducted. Two parent materials, whole cane (WC) and stripped cane (SC), were included in the study. The whole cane material was subjected to three treatments: (1) no treatment, WC-U; (2) a single milling, WC-M; and (3) an initial milling followed by leaching and a secondary milling, WC-MLM. Treatments (1) through (3) are in order of increasing severity. The stripped cane material was subjected to treatment (3) and designated as SC-MLM. Regardless of parent material, milling produced moisture contents of ∼50% wet basis and fiber bulk …

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Comprehensive Model Of Alkali-Salt Deposition In Recovery Boilers, Richard A. Wessel, Larry Lin Baxter 8507091 Feb 2003

Comprehensive Model Of Alkali-Salt Deposition In Recovery Boilers, Richard A. Wessel, Larry Lin Baxter 8507091

Faculty Publications

Algorithms for alkali-salt deposition have been implemented into a comprehensive model for recovery boilers. The model includes (a) mechanisms for particle formation and chemistry, (b) particle deposition and adhesion, and (c) deposit thermal properties. These algorithms are fully coupled with models for turbulent flow, black liquor combustion, and heat transfer in the boiler. Model predictions for particle deposition in the convection pass are presented for a Babcock & Wilcox recovery boiler. This work is part of an ongoing project sponsored by the U.S. Department of Energy to demonstrate an improved ability to anticipate ash behavior with changes in fuel composition, …

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High-Pressure Coal Pyrolysis In A Drop Tube Furnace, Koichi Matsuoka, Zhi-Xin Ma, Hiroyuki Akiho, Zhan-Guo Zhang, Akira Tomita, Thomas H. Fletcher, Marek A. Wojtowicz, Stephen Niksa Jan 2003

High-Pressure Coal Pyrolysis In A Drop Tube Furnace, Koichi Matsuoka, Zhi-Xin Ma, Hiroyuki Akiho, Zhan-Guo Zhang, Akira Tomita, Thomas H. Fletcher, Marek A. Wojtowicz, Stephen Niksa

Faculty Publications

To obtain useful and reliable pyrolysis data under high pressures, continuous pyrolysis experiments were carried out using a drop tube furnace. To ascertain the reliability of data, a mass balance during pyrolysis was carefully checked. The pyrolysis data obtained in this equipment was compared with previous results, and it was found that the weight loss observed in the drop tube furnace was somewhat larger than those obtained with other apparatuses. The experimental results were compared with those predicted by three pyrolysis models. Although discrepancies between predictions and experimental results were observed under a certain condition, the agreement between the experimental …

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High-Pressure Intrinsic Oxidation Kinetics Of Two Coal Chars, William C. Hecker, Peter M. Madsen, Michael R. Sherman, Jared W. Allen, Rebecca J. Sawaya, Thomas H. Fletcher Jan 2003

High-Pressure Intrinsic Oxidation Kinetics Of Two Coal Chars, William C. Hecker, Peter M. Madsen, Michael R. Sherman, Jared W. Allen, Rebecca J. Sawaya, Thomas H. Fletcher

Faculty Publications

Chars were produced from two coals (North Dakota lignite and Pittsburgh No. 8 hva bituminous coal) in a flat flame burner at atmospheric pressure. Intrinsic char reactivities to oxygen were then measured in a high-pressure thermogravimetric analyzer as a function of temperature, total pressure, and partial pressure of oxygen. Care was taken to avoid mass transfer effects. Reactivities were normalized by the available mass of char at any given time (g/(gavailâs)). Reactivity data were obtained over a wide range of char burnout and were found to be independent of burnout level between char burnouts of 20 and 60%. Data were …

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