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DETERMINATION OF THE FORMS OF NITROGEN RELEASED IN COAL TAR DURING RAPID DEVOLATILIZATION

Description: The primary objective of this work is to determine the forms of nitrogen in coal that lead to nitrogen release during devolatilization. Experiments are to be performed in two existing laminar flow reactors available at Brigham Young University, which are both capable of temperatures (up to 2000 K), particle heating rates (10 4 to 10 5 K/s), and residence times (up to 500 ms) relevant to conditions commonly encountered in industrial pulverized coal combustors. The forms of nitrogen in coal, char, and tar samples are analyzed using state-of-the-art techniques, including nuclear magnetic resonance (NMR), X-Ray photoelectron spectroscopy (XPS), and high resolution nitrogen-specific chromatography. These sophisticated analysis techniques are being performed in collaboration with other researchers at BYU, the University of Utah, and industrial organizations. Coals have been obtained as a function of rank, including eight coals from the University of Utah that are to be used in pilot scale tests in support of the DOE Coal-2000 HiPPS (High Performance Power Systems) and LEBS (Low-Emission Boiler Systems) programs. Results from the proposed research are (a) nitrogen release parameters during devolatilization for specific coals pertinent to the HiPPS and LEBS projects, (b) better fundamental understanding of the chemistry of nitrogen release, and (c) a nitrogen release submodel based on fundamental chemistry that may be more widely applicable than existing empirical relationships.
Date: October 30, 1998
Partner: UNT Libraries Government Documents Department

Determination of the Forms of Nitrogen Released in Coal Tar During Rapid Devolatilization

Description: The primary objective of this work is to determine the forms of nitrogen in coal that lead to nitrogen release during devolatilization. Experiments are to be performed in two existing laminar flow reactors available at Brigham Young University, which are both capable of temperatures (up to 2000 K), particle heating rates (10 4 to 10 5 K/s), and residence times (up to 500 ms) relevant to conditions commonly encountered in industrial pulverized coal combustors. The forms of nitrogen in coal, char, and tar samples are analyzed using state-of-the-art techniques, including nuclear magnetic resonance (NMR), X-Ray photoelectron spectroscopy (XPS), and high resolution nitrogen-specific chromatography. These sophisticated analysis techniques are being performed in collaboration with other researchers at BYU, the University of Utah, and industrial organizations. Coals have been obtained as a function of rank, including eight coals from the University of Utah that are to be used in pilot scale tests in support of the DOE Coal-2000 HiPPS (High Performance Power Systems) and LEBS (Low-Emission Boiler Systems) programs. Anticipated results from the proposed research are (a) nitrogen release parameters during devolatilization for specific coals pertinent to the HiPPS and LEBS projects, (b) better fundamental understanding of the chemistry of nitrogen release, and (c) a nitrogen release submodel based on fundamental chemistry that may be more widely applicable than existing empirical relationships.
Date: May 30, 1998
Creator: Fletcher, Thomas H.
Partner: UNT Libraries Government Documents Department

Determination of the Forms of Nitrogen Released in Coal Tar During Rapid Devolatilization. Semi-annual report, May 1-October 31, 1997

Description: The primary objective of this work is to determine the forms of nitrogen in coal that lead to nitrogen release during devolatilization. Experiments are to be performed in two existing laminar flow reactors available at Brigham Young University, which are both capable of temperatures (up to 2000 K), particle heating rates (104 to 105 K/s), and residence times (up to 500 ms) relevant to conditions commonly encountered in industrial pulverized coal combustors. The forms of nitrogen in coal, char, and tar samples are analyzed using state-of-the-art techniques, including nuclear magnetic resonance (NMR), X-Ray photoelectron spectroscopy (XPS), and high resolution nitrogen-specific chromatography. These sophisticated analysis techniques are being performed in collaboration with other researchers at BYU, the University of Utah, and industrial organizations. Coals have been obtained as a function of rank, including eight coals from the University of Utah that are to be used in pilot scale tests in support of the DOE Coal-2000 HIPPS (High Performance Power Systems) and LEBS (Low- Emission Boiler Systems) programs. Anticipated results from the proposed research are (a) nitrogen release parameters during devolatilization for specific coals pertinent to the HIPPS and LEBS projects, (b) better fundamental understanding of the chemistry of nitrogen release, and (c) a nitrogen release submodel based on fundamental chemistry that may be more widely applicable than existing empirical relationships.
Date: October 31, 1997
Creator: Fletcher, T.H., Goldberg, P.
Partner: UNT Libraries Government Documents Department

Cost-Effective Control of NOx With Integrated Ultra Low-NOx Burners and SNCR

Description: Under sponsorship of the Department of Energy's National Energy Technology Laboratory (NETL), McDermott Technology, Inc. (MTI), the Babcock & Wilcox Company (B&W), and Fuel Tech teamed together to investigate an integrated solution for NOx control. The system was comprised of B&W's DRB-4Z{trademark} low-NO{sub x} pulverized coal (PC) burner technology and Fuel Tech's NO{sub x}OUT{reg_sign}, a urea-based selective non-catalytic reduction (SNCR) technology. The technology's emission target is achieving 0.15 lb NO{sub x}/10{sup 6} Btu for full-scale boilers. Development of the low-NOx burner technology has been a focus in B&W's combustion program. The DRB-4Z{trademark} burner (see Figure 1.1) is B&W's newest low-NO{sub x} burner capable of achieving very low NO{sub x}. The burner is designed to reduce NO{sub x} by diverting air away from the core of the flame, which reduces local stoichiometry during coal devolatilization and, thereby, reduces initial NO{sub x} formation. Figure 1.2 shows the historical NO{sub x} emission levels from different B&W burners. Figure 1.2 shows that based on three large-scale commercial installations of the DRB-4Z{trademark} burners in combination with OFA ports, using Western subbituminous coal, the NO{sub x} emissions ranged from 0.16 to 0.18 lb/10{sup 6} Btu. It appears that with continuing research and development the Ozone Transport Rule (OTR) emission level of 0.15 lb NO{sub x}/10{sup 6} Btu is within the reach of combustion modification techniques for boilers using western U.S. subbituminous coals. Although NO{sub x} emissions from the DRB-4Z{trademark} burner are nearing OTR emission level with subbituminous coals, the utility boiler owners that use bituminous coals can still benefit from the addition of an SNCR and/or SCR system in order to comply with the stringent NO{sub x} emission levels facing them.
Date: July 1, 2003
Creator: Farzan, Hamid; Sivy, Jennifer; Sayre, Alan & Boyle, John
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

Description: The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly fly ash containing unburned carbon. However, the carbonaceous residue in fly ash, unburned carbon (UC), is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, this research program focuses on the development of activated carbons from the unburned carbon present in fly ash. During the present reporting period (June 30, 1999--June 29, 2000), Task 1 ''Procurement and characterization of CCBPs'' was initiated and samples from various combustion systems were collected. The suite assembled thus far includes samples from pulverized utility boilers with low-NOx burners and Selective Non Catalytic Reduction system, and also from an utility cyclone unit. The characterization studies showed that the sample from the cyclone unit contained the highest carbon content (LOI of {approx} 80%), since this unit has been retrofitted with a technology to separate the unburned carbon from the fly ash. In contrast, the sample from the unit retrofitted with a Selective Non Catalytic Reduction system showed the lowest carbon content with LOI values around 2-4%. The samples from the utility boilers with low-NOx burners were collected from the hot-side hoppers and present carbon contents {approx} 50%. The BET (N{sub 2} 77K) surface areas of the samples investigated were between 30-40 m{sup 2}/g and the pore volume is mainly due to mesopores. In addition, during this reporting period, also Task 2 ''Development of activated carbons'' and Task 3 ''Characterization of activated carbons'' were initiated. The investigations showed that after steam activation at 850 C, the unburned carbon samples generated activated carbons with microporous structure and surface areas ...
Date: July 31, 2000
Creator: Schobert, Prof. Harold H.; Maroto-Valer, Dr. M. Mercedes & Lu, Ms. Zhe
Partner: UNT Libraries Government Documents Department

Linkages between aromatic structures in the Argonne Premium Coal Samples

Description: The objective of this study is to elucidate the nature of the important linkages between aromatic clusters and variations of these links with coal rank. From studies using methods such as NMR and mass spectrometry, the authors have considerable information on the size and types of aromatic clusters in the Argonne coals. In this study, extracts, model polymers, extracted coals, and modified coals are examined by temperature resolved high resolution mass spectrometry. There is evidence that strong bond cleavage may be very important for volatile release in pyrolysis of higher rank coals.
Date: April 1, 1997
Creator: Winans, R.E. & Tomczyk, N.A.
Partner: UNT Libraries Government Documents Department

Hot isostatic press waste option study report

Description: A Settlement Agreement between the Department of Energy and the State of Idaho mandates that all high-level radioactive waste now stored at the Idaho Chemical Processing Plant be treated so that it is ready to move out of Idaho for disposal by the target date of 2035. This study investigates the immobilization of all Idaho Chemical Processing Plant calcine, including calcined sodium bearing waste, via the process known as hot isostatic press, which produces compact solid waste forms by means of high temperature and pressure (1,050 C and 20,000 psi), as the treatment method for complying with the settlement agreement. The final waste product would be contained in stainless-steel canisters, the same type used at the Savannah River Site for vitrified waste, and stored at the Idaho National Engineering and Environmental Laboratory until a national geological repository becomes available for its disposal. The waste processing period is from 2013 through 2032, and disposal at the High Level Waste repository will probably begin sometime after 2065.
Date: February 1, 1998
Creator: Russell, N.E. & Taylor, D.D.
Partner: UNT Libraries Government Documents Department

Proposed experiment for SnCl{sub 2} treatment of Outfall 200 for the purpose of mercury removal from East Fork Poplar Creek, Y-12 Plant, Oak Ridge, Tennessee

Description: Identification and treatment/elimination of point sources of mercury (Hg) to East Fork Poplar Creek (EFPC) within the Y-12 Plant have reduced base flow mercury concentrations considerably; but, after all such actions are completed, nonpoint sources will continue to add mercury to the creek. Studies conducted in 1996 on the use of air stripping to remove elemental mercury from Outfall 51, a mercury-contaminated natural spring, demonstrated that the addition of trace concentrations of stannous chloride (SnCl{sub 2}) converted a large fraction of the dissolved mercury in the outfall to elemental mercury, which could subsequently be removed by air stripping. Dissolved mercury is the dominant form in EFPC at the north/south (N/S) pipes, where it emerges from the underground storm drain network. More than 50% of that mercury is capable of being rapidly reduced by the addition of a 3--5 fold molar excess of stannous chloride. Upon conversion to the volatile gaseous (elemental) form, mercury would be lost across the air-water interface through natural volatilization. EFPC within the Y-12 Plant is shallow, turbulent, and open to sunlight and wind, providing conditions that facilitate natural evasion of volatile chemicals from the water. Preliminary calculations estimate that 75% or more of the elemental mercury could be removed via evasion between the N/S pipes and the Y-l2 Plant boundary (Station 17). Alternatively, elemental mercury might be removed from EFPC in a short reach of stream below the N/S pipes by an in-situ air stripping system which bubbles air through the water column. The purpose of these proposed experiments is to test whether natural volatilization or in-situ air stripping may be used to further reduce baseflow concentrations of mercury in EFPC. Results of this experiment will be useful for understanding the transport and fate of other volatile chemicals in the upper reaches of EFPC.
Date: March 1, 1997
Creator: Southworth, G.R.
Partner: UNT Libraries Government Documents Department

Experimental investigation of kinetics and rheology during diagenesis

Description: Two processes of enormous economic consequence occur within the upper to middle crust: the formation, migration, entrapment, and degradation of hydrocarbons, and hazardous seismicity. Substantial scientific evidence suggests that both these processes are influenced by devolatilization reactions during diagenesis. However, surprisingly few laboratory studies have been conducted on materials actively undergoing low-grade metamorphism or diagenesis. Because of this, there exists no suitable basis for understanding the rates at which devolatilization occurs, and what effects this process has on deformation at shallow to moderate depths in the crust. The authors are conducting a coordinated deformation and kinetic study of an important devolatilization reaction: the breakdown of laumontite. Laumontite is a common zeolite whose equilibrium phase relations and room-temperature frictional behavior are well understood. Besides serving as a model system for more complicated rocks, laumontite is an important mineral in its own right, particularly for hydrocarbon fields in sandstones and for fault zones in the crust. Hydrostatic experiments are being conducted to investigate the kinetics and mechanism of laumontite dehydration, and triaxial deformation experiments will enable characterization of the effect of differential stress on the reaction and the effect of synkinematic dehydration on the mechanical behavior of rock. The authors anticipate results of significant import for hydrocarbon exploration and recovery and for understanding the strength and seismic potential of crustal fault zones.
Date: September 1, 1998
Creator: Liou, J.G. & Hacker, B.R.
Partner: UNT Libraries Government Documents Department

Low VOC drying of lumber and wood panel products. Progress report number 9

Description: This project is based on the finding that brief microwave or RF-treatment of wood under low-headspace conditions leads to the release of VOCs. On occasion the authors have found that prolonged irradiation increases turpentine yield much more than anticipated from a simple mass balance; i.e., more pinene appeared to be released than was present in the wood in the first place. If taken at face value, this suggests that brief low-headspace irradiation removes VOCs, while prolonged exposure creates it. While seemingly improbable, this could follow if dielectric heating exposed regions of wood that were otherwise inaccessible to the solvent used for extraction (unlikely), or if the irradiation induced depolymerization of terpene dimers or higher polymers. In this report the authors attempt to identify the conditions that lead to this apparent enhancement of terpene yield, by constructing relationships between yield and irradiation parameters. The tentative conclusions are that this enhancement only occurs with relatively wet heartwood, and only under prolonged irradiation. An additional conclusion is that continuing analyses of twelve trees in the MSU forest confirm that the absence of a significant seasonal influence on turpentine content. An apparatus for permeability testing has been constructed, and work is underway.
Date: October 1, 1998
Creator: Hooda, U.; Banerjee, S.; Ingram, L. & Conners, T.
Partner: UNT Libraries Government Documents Department

HIGH PRESSURE COAL COMBUSTION KINETICS PROJECT

Description: The HPCCK project was initiated with a kickoff meeting held on June 12, 2001 in Morgantown, WV, which was attended by all project participants. SRI's existing g-RCFR reactor was reconfigured to a SRT-RCFR geometry (Task 1.1). This new design is suitable for performing the NBFZ experiments of Task 1.2. It was decided that the SRT-RCFR apparatus could be modified and used for the HPBO experiments. The purchase, assembly, and testing of required instrumentation and hardware is nearly complete (Task 1.1 and 1.2). Initial samples of PBR coal have been shipped from FWC to SRI (Task 1.1). The ECT device for coal flow measurements used at FWC will not be used in the SRI apparatus and a screw type feeder has been suggested instead (Task 5.1). NEA has completed a upgrade of an existing Fluent simulator for SRI's RCFR to a version that is suitable for interpreting results from tests in the NBFZ configuration (Task 1.3) this upgrade includes finite-rate submodels for devolatilization, secondary volatiles pyrolysis, volatiles combustion, and char oxidation. Plans for an enhanced version of CBK have been discussed and development of this enhanced version has begun (Task 2.5). A developmental framework for implementing pressure and oxygen effects on ash formation in an ash formation model (Task 3.3) has begun.
Date: September 15, 2001
Creator: Guenther, Chris & Rogers, Bill
Partner: UNT Libraries Government Documents Department

Release of inorganic material during coal devolatilization. Milestone report

Description: Experimental results presented in this paper indicate that coal devolatilization products convectively remove a fraction of the nonvolatile components of inorganic material atomically dispersed in the coal matrix. Results from three facilities burning six different coals illustrate this mechanism of ash transformation and release from coal particles. Titanium is chosen to illustrate this type of mass release from coal particles on the basis of its low volatility and mode of occurrence in the coal. During moderate rates of devolatilization (10{sup 4} K/s heating rate), no significant loss of titanium is noted. At more rapid rates of heating/devolatilization (10{sup 5} K/s) a consistent but minor (3-4 %) loss of titanium is noted. During rapid devolatilization (5xl0{sup 5} K/s and higher), significant (10-20 %) amounts of titanium leave the coal. The loss of titanium monitored in coals ranging in rank from subbituminous to high-volatile bituminous coals and under conditions typical of pulverized-coal combustion. The amount of titanium lost during devolatilization exhibits a complex rank dependence. These results imply that other atomically dispersed material (alkali and alkaline earth elements) may undergo similar mechanisms of transformation and release.
Date: July 1, 1995
Creator: Baxter, L.L.
Partner: UNT Libraries Government Documents Department

Addition of devolatilization equations to synthane computerized mathematical model. Quarterly report, September 15--December 15, 1978

Description: Six approaches to devolatilization modeling have been reviewed. Two have been selected for further evaluation: the Vand-type model of Anthony and Howard and the diffusion model of Russel et al. The first of these treats particles under kinetic control only. The second includes some mass transfer control along with kinetic control. Behavior of particles in the SYNTHANE process appears to be in the transition region between kinetic and mass transfer control. Work during the next quarter will focus on the temperature history of average particles in the carbonizer of the SYNTHANE process and on the methods by which the two devolatilization models chosen will be used to describe conversion in the SYNTHANE carbonizer.
Date: January 1, 1979
Creator: Cobb, J.T. Jr.
Partner: UNT Libraries Government Documents Department

Investigation of the rank dependence of tar evolution. Quarterly report, 1 July 1990--30 September 1990

Description: Despite its high nitrogen concentration levels relative to the parent coal samples, 7.2% vs. 1.4 - 2.0%, little volatile nitrogen evolution is observed until decomposition temperatures of 600{degree}C or greater are obtained. Due to the lack of decomposition via tar evolution and as contrasted to parent coals, no significant bound nitrogen is evolved with heavy hydrocarbons at particle temperatures less than 600{degree}C. Similar to ``virgin`` chars and tars formed during rapid devolatilization, the polyimide samples begin to evolve significant fractions of bound nitrogen as IR-active light gases at particle temperatures between 650 and 750{degree}C. Unlike coal samples, however, relatively large fractions of the light gases are observed to be ammonia. The IR-active, nitrogen-containing light gas evolution rapidly declines at polyimide char temperatures greater than 750{degree}C, again in contrast to observed behavior in virgin coal char samples. It is not certain if the nitrogen evolution kinetics changes from selectively forming ammonia and hydrogen cyanide to benzonitriles or free nitrogen at these temperatures. The light gas evolution pattern with decomposition temperature of polymide could contribute to our understanding of the low conversion efficiencies observed for bound nitrogen to NO{sub x} conversion in the char combustion phase of pfc combustion.
Date: December 31, 1990
Creator: Freihaut, J. D. & Proscia, W. M.
Partner: UNT Libraries Government Documents Department

A Mechanistic Investigation of Nitrogen Evolution and Corrosion with Oxy-Combustion

Description: A premixed, staged, down-fired, pulverized coal reactor and a flat flame burner were used to study the evolution of nitrogen in coal contrasting differences in air and oxy-combustion. In the premixed reactor, the oxidizer was staged to produce a fuel rich zone followed by a burnout zone. The initial nominal fuel rich zone stoichiometric ratio (S.R.) of 0.85 selected produced higher NO reductions in the fuel rich region under oxy-combustion conditions. Air was found to be capable of similar NO reductions when the fuel rich zone was at a much lower S.R. of 0.65. At a S.R. of 0.85, oxy-combustion was measured to have higher CO, unburned hydrocarbons, HCN and NH{sub 3} in the fuel rich region than air at the same S.R. There was no measured difference in the initial formation of NO. The data suggest devolatilization and initial NO formation is similar for the two oxidizers when flame temperatures are the same, but the higher CO{sub 2} leads to higher concentrations of CO and nitrogen reducing intermediates at a given equivalence ratio which increases the ability of the gas phase to reduce NO. These results are supported by flat flame burner experiments which show devolatilization of nitrogen from the coal and char to be similar for air and oxy-flame conditions at a given temperature. A model of premixed combustion containing devolatilization, char oxidation and detailed kinetics captures most of the trends seen in the data. The model suggests CO is high in oxy-combustion because of dissociation of CO{sub 2}. The model also predicts a fraction (up to 20%, dependent on S.R.) of NO in air combustion can be formed via thermal processes with the source being nitrogen from the air while in oxy-combustion equilibrium drives a reduction in NO of similar magnitude. The data confirm oxy-combustion is a ...
Date: December 31, 2008
Creator: Tree, Dale; Mackrory, Andrew & Fletcher, Thomas
Partner: UNT Libraries Government Documents Department

EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL

Description: This semi-annual technical progress report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period March 24, 1999 to September 23, 1999 which covers the last (sixth) six months of the project. During this reporting period, extraction of devolatilization time-scales and temperature data at these time-scales analyzing the high-speed films taken during the experiments was complete. Also a new thermodynamic model was developed to predict the heat transfer behavior for coal particles subjected to a range of heating rates using one approach based on the analogy of polymers. Sensitivity analyses of this model suggest that bituminous coal particles behave like polymers during rapid heating on the order of 10{sup 4}-10{sup 7} K/s. At these heating rates during the early stages within the first few milliseconds of heating time, the vibrational part of the heat capacity of the coal molecules appears to be still frozen but during the transition from heat-up to devolatization, the heat capacity appears to attain a sudden jump in its value as in the case of polymers. There are few data available in the coal literature for 10{sup 2}-10{sup 3} K/s obtained by UTRC in their previous studies. These data were obtained for a longer heating duration on the order of several seconds as opposed to the 10 milliseconds heating time in the single particle experiments discussed above. The polymer analogy model is being modified to include longer heating time on the order of several seconds to test these data. It is expected that the model might still do a good job in the case of these larger heating time but very low heating rate experiments. Completion of the numerical analysis of the experimental data and preparation of the final report are in progress.
Date: November 2, 1999
Creator: Sampath, Ramanathan
Partner: UNT Libraries Government Documents Department

Determination of the forms of nitrogen released in coal tar during rapid devolatilization. Semi-annual report, November 1, 1995--April 30, 1996

Description: Control of emissions of nitrogen oxides (NO{sub x}) from coal combustion systems is becoming a major design and retrofit consideration. Most NO{sub x} in coal combustion systems comes from nitrogen in the fuel, rather than from nitrogen in the air. Practical emission control strategies include burner design strategies (e.g., low NO{sub x} burners), overfire air, reburning, selective non-catalytic reduction (SNCR) using reduction agents such as NH{sub 3} or urea, and selective catalytic reduction (SCR). The order listed also reflects the order of increasing costs for implementation. It is therefore most economically desirable to perform burner modifications to reduce NO{sub x} emissions rather than other control measures. Low-NO{sub x} burners work on the principle that devolatilized nitrogen species will form N{sub 2} rather than NO{sub x} under locally fuel-rich conditions with sufficient residence time at appropriate temperatures. The amount and form of nitrogen released during devolatilization influence the degree of NO{sub x} reduction attainable using burner design strategies for a given coal. Nitrogen in the char following devolatilization is released by heterogeneous oxidation, and may not be controlled by aerodynamic burner modifications. The objectives of this work are to perform detailed chemical measurements of the nitrogen in coal, tar, and char.
Date: April 30, 1996
Creator: Fletcher, T.H.
Partner: UNT Libraries Government Documents Department

Thermodynamic properties of pulverized coal during rapid heating devolatilization processes

Description: The thermodynamic properties of coal under conditions of rapid heating have been determined using a combination of UTRC facilities including a proprietary rapid heating rate differential thermal analyzer (RHR-DTA), a microbomb calorimeter (MBC), an entrained flow reactor (EFR), an elemental analyzer (EA), and a FT-IR. The total heat of devolatilization, was measured for a HVA bituminous coal (PSOC 1451D, Pittsburgh No. 8) and a LV bituminous coal (PSOC 1516D, Lower Kittaning). For the HVA coal, the contributions of each of the following components to the overall heat of devolatilization were measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Morphological characterization of coal and char samples was performed at the University of Pittsburgh using a PC-based image analysis system, BET apparatus, helium pcynometer, and mercury porosimeter. The bulk density, true density, CO{sub 2} surface area, pore volume distribution, and particle size distribution as a function of extent of reaction are reported for both the HVA and LV coal. Analyses of the data were performed to obtain the fractal dimension of the particles as well as estimates for the external surface area. The morphological data together with the thermodynamic data obtained in this investigation provides a complete database for a set of common, well characterized coal and char samples. This database can be used to improve the prediction of particle temperatures in coal devolatilization models. Such models are used both to obtain kinetic rates from fundamental studies and in predicting furnace performance with comprehensive coal combustion codes. Recommendations for heat capacity functions and heats of devolatilization for the HVA and LV coals are given. Results of sample particle temperature calculations using the recommended thermodynamic properties are provided.
Date: July 1, 1994
Creator: Proscia, W.M.; Freihaut, J.D.; Rastogi, S. & Klinzing, G.E.
Partner: UNT Libraries Government Documents Department

Low VOC drying of lumber and wood panel products. Progress report number 6

Description: Twenty five Southern pine boards were machined into 2 x 4 inch pieces. Next, the 8 foot boards were cut in half into matched pairs. One of the two was irradiated with RF, while the other served as a control. Both sets were dried under a conventional temperature-time based schedule. Results and conclusions are: RF pretreatment of lumber does not affect strength; the amount of pinene lost into the headspace during low-VOC RF-treatment of wood approximately corresponds to the amount of material lost from the wood; virtually all the pinene can be removed from the low-VOC reactor with steam, suggesting that pinene can be collected when the small amount of steam released during low-headspace treatment is condensed; temperature and moisture loss profiles for particle at 105 C has been modeled using experimental data at 130 C and 160 C; the VOC-temperature curve from dried particle shows a break at about 156 C, the boiling point of {alpha}-pinene, demonstrating that pinene boil-off occurs beyond this threshold; VOC release from dry particle has been successfully modeled; the transport of VOC from sapwood to the atmosphere for pine is faster than the corresponding movement from heartwood to sapwood; and seasonal variations in pine extractives are small.
Date: January 1, 1998
Creator: Yan, H.; Wild, M.P.; Hooda, U.; Banerjee, S.; Shmulsky, R.; Thompson, A. et al.
Partner: UNT Libraries Government Documents Department

Fossil fuel conversion -- Measurement and modeling. Topical report, September 14, 1993--June 30, 1997

Description: Progress is described on the following tasks: Fixed-bed devolatilization processes; Fixed-bed combustion and gasification processes; Physical processes in transport reactors; Chemical processes in transport reactors; Advanced fixed-bed model development and evaluation; Advanced two-dimensional transport reactor model development and evaluation; Modeling of gas phase combustion; Modeling of fluidized bed systems; Advanced fixed-bed code application and implementation; Advanced two-dimensional transport gasification code applications and implementation; Modeling of fluidized-bed system applications and implementation; and Applications of ACERC combustion and gasification codes and AFR diagnostic capabilities to systems of interest to METC.
Date: December 31, 1997
Partner: UNT Libraries Government Documents Department

Low VOC drying of lumber and wood panel products. Progress report No. 8

Description: This study was initiated by an Institute of Paper Science and Technology finding that heating softwood in a low-headspace environment removed much of the VOCs without removing the water. This offered the possibility of removing VOCs from wet wood, capturing them as a product, and then drying the VOC-depleted wood conventionally with little or no VOC controls. Two means of low-headspace heating were explored: steam and radiofrequency (RF). It was found in the previous year, that while both steam and RF were able to drive out VOCs, steam was impracticably slow for lumber. Hence the effect of RF or microwave on wood was the principal focus of the work reported here. Finally, in order to understand the mechanism of VOC release, the transport of the VOCs in wood was studied, together with the seasonal effects that influence VOC concentration in trees.
Date: July 1, 1998
Creator: Su, W.; Yan, H.; Hooda, U.; Wild, M.P.; Banerjee, S.; Shmulsky, R. et al.
Partner: UNT Libraries Government Documents Department

MINIMIZATION OF NO EMISSIONS FROM MULTI-BURNER COAL-FIRED BOILERS

Description: Reduction of NO{sub x} emission is an important environmental issue in pulverized coal combustion. The most cost-effective approach to NO{sub x} reduction is air-staging which can also operate with additional down-stream techniques such as reburning [1]. Air staging promotes the conversion of NO{sub x} precursors (HCN, NH{sub 3}, etc.) to N{sub 2} by delaying the oxygen supply to the greatest extent when those nitrogen species are released during devolatilization. Such a delay gives the primary volatiles a chance to undergo secondary reactions, including tar cracking and soot formation. Secondary reactions of volatiles largely determine the fate of the ultimate NO{sub x} production from pyrolysis, therefore a detailed investigation into the transformation of nitrogen species during secondary reactions and effects of soot on nitrogen release is critical for design and implementation of new pollution control strategies. Current nitrogen models (including the CPD model at BYU) only simulate the nitrogen release during primary pyrolysis, which happens at low temperatures. This project helps to build a nitrogen release model that accounts for secondary reactions and the effects of soot at temperatures relevant to industrial burners.
Date: April 1, 2000
Creator: Eddings, E.G.; Molina, A.; Pershing, D.W.; Sarofim, A.F.; Davis, K.A.; Heap, M.P. et al.
Partner: UNT Libraries Government Documents Department

MINIMIZATION OF NO EMISSIONS FROM MULTI-BURNER COAL-FIRED BOILERS

Description: Reduction of NO{sub x} emission is an important environmental issue in pulverized coal combustion. Final emissions of NO{sub x} are strongly affected by the nitrogen release during devolatilization, which is the first stage of coal combustion. The most cost-effective approach to NO{sub x} reduction is air-staging which can also operate with additional down-stream techniques such as reburning [1]. Air staging promotes the conversion of NO{sub x} precursors (HCN, NH{sub 3}, etc.) to N{sub 2} by delaying the oxygen supply to the greatest extent when those nitrogen species are released during devolatilization. Such a delay gives the primary volatiles a chance to undergo secondary reactions, including tar cracking and soot formation. Secondary reactions of volatiles largely determine the fate of the ultimate NO{sub x} production from pyrolysis, therefore a detailed investigation into the transformation of nitrogen species during secondary reactions and effects of soot on nitrogen release is critical for design and implementation of new pollution control strategies. Current nitrogen models (including the CPD model at BYU) only simulate the nitrogen release during primary pyrolysis, which happens at low temperatures. This project helps to build a nitrogen release model that accounts for secondary reactions and the effects of soot at temperatures relevant to industrial burners.
Date: April 1, 2000
Creator: Eddings, E.G.; Molina, A.; Pershing, D.W.; Sarofim, A.F.; Davis, K.A.; Heap, M.P. et al.
Partner: UNT Libraries Government Documents Department

MINIMIZATION OF NO EMISSIONS FROM MULTI-BURNER COAL-FIRED BOILERS

Description: Reduction of NO{sub x} emission is an important environmental issue in pulverized coal combustion. The most cost-effective approach to NO{sub x} reduction is air-staging which can also operate with additional down-stream techniques such as reburning [1]. Air staging promotes the conversion of NO{sub x} precursors (HCN, NH{sub 3}, etc.) to N{sub 2} by delaying the oxygen supply to the greatest extent when those nitrogen species are released during devolatilization. Such a delay gives the primary volatiles a chance to undergo secondary reactions, including tar cracking and soot formation. Secondary reactions of volatiles largely determine the fate of the ultimate NO{sub x} production from pyrolysis, therefore a detailed investigation into the transformation of nitrogen species during secondary reactions and effects of soot on nitrogen release is critical for design and implementation of new pollution control strategies. Current nitrogen models (including the CPD model at BYU) only simulate the nitrogen release during primary pyrolysis, which happens at low temperatures. This project helps to build a nitrogen release model that accounts for secondary reactions and the effects of soot at temperatures relevant to industrial burners.
Date: April 1, 2000
Creator: Eddings, E.G.; Molina, A.; Pershing, D.W.; Sarofim, A.F.; Davis, K.A.; Heap, M.P. et al.
Partner: UNT Libraries Government Documents Department