ACERC
Abstracts - 1989 |
ACERC
Abstracts - 1989 |
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Thrust Area 3: Pollutant Formation/Control and Waste Incineration |
Lighty, J.S.; Silcox, G.D.;
Pershing, D.W.; Cundy, V.A. and Linz, D.G.
Environmental Progress, 8 (1), 1989. Funded by the Gas Research Institute,
Dave Linz, Project Manager, National Science Foundation - Presidential Young
Investigator Program, ACERC (National Science Foundation and Associates and
Affiliates), the State of Utah, and US Department of Energy.
The goals of this research are to develop an understanding of the transport phenomena that occur during the desorption of contaminants from soil and to obtain rate information. This information can then be used to develop a model to predict the performance of full-scale thermal treatment systems for optimization and cost reduction.
Silcox, G.D. and Pershing,
D.W.
Accepted for publication in JAPCA, 1989. Funded by ACERC (National Science
Foundation and Associates and Affiliates), the State of Utah, and US Department
of Energy.
A mathematical model of heat transfer in a directly fired rotary kiln is developed and used to examine the effects of operating and design parameters on burden temperature. The model includes a mean beam length radiation model and axial zoning. Conductive and convective heat transfers are also included. Radiation between immediately adjacent zones is permitted. Calculation of heat transfer rates is facilitated by the use of an electric circuit analogue. An iterative solution procedure is adopted to solve the energy balance equations.
At the conditions examined, the model predicts that coflowing gas and solid streams result in higher average burden temperatures than do counter flowing streams. The moisture level of the feed is predicted to be a key operating parameter. The effects of kiln length, burden residence time, firing rate, and flame length are also examined.
Milne, C.R.; Silcox, G.D.;
Pershing, D.W. and Kirchgessner, D.A.
Accepted for publication in I & EC Res., 1989. Funded by the US Environmental
Protection Agency, ACERC (National Science Foundation and Associates and Affiliates),
the State of Utah, and US Department of Energy.
To simulate the staged availability of transient high surface area CaO observed in high-temperature flow-reactor data, the rate of calcination of CaCO3 or Ca(OH)2 is described by an empirical modification of the shrinking-core model. The physical model depicts particle decomposition by the shrinking-core mechanism. The subsequent time dependent decrease in CaO reactivity (surface area and porosity) due to sintering is simulated by reducing the grain-center spacing for the matrix of overlapping CaO grains. Information from SEM micrographs and from other physical property measurements of the porous particles is incorporated. This submodel simulates the time dependent availability and reactivity of CaO for a comprehensive model used to study sulfation of CaCO3 or Ca(OH)2 particles at upper-furnace injection conditions.
Cundy, V.A.; Lester, T.W.;
Leger, C.B.; Miller, G.; Montestruc, A.N.; Acharya, S.; Sterling, A.M.; Pershing,
D.W.; Lighty, J.S.; Silcox, G.D. and Owens, W.D.
Journal of Hazardous Materials, 22, 195-219,1989. Funded by US Environmental
Proctection Agency and ACERC (National Science Foundation and Associates and
Affiliates).
A multifaceted experimental and theoretical program aimed at understanding rotary kiln performance is underway. The overall program involves university, industry, and government participation and is broken into distinct sub-programs. This paper discusses in some detail the research effort performed to date in two of the sub-programs: Full-scale in situ sampling and kiln-simulator experimentation. Full-scale in situ measurements are obtained from the Louisiana Division rotary kiln facility of Dow Chemical USA, located in Plaquemine, Louisiana. Summary results obtained from controlled experiments that were performed during continuous processing of carbon tetrachloride and preliminary results obtained during batch mode processing of toluene-laden sorbent packs are presented. Kiln-simulator data are obtained by using the facilities of the Chemical Engineering Department at the University of Utah. Recent kiln-simulator work, conducted in support of the full-scale measurements sub-program, has aided in providing an understanding of the results that have been obtained at the full-scale. Modeling efforts, conducted at Louisiana State University and the University of Utah, have concentrated on the development of realistic, fluid-flow and heat-transfer models, near-term chlorinated kinetic models and bed mass-transfer models to be incorporated into a global three-dimensional kiln-simulator model. The paper concludes with an overview of these modeling efforts.
Winter, R.M.; Clough, J.;
Overmoe, B.J. and Pershing, D.W.
Tappi Journal, 72(4):139-145, 1989. Funded by Weyerhaeuser Corp.
A 65-kW refractory-walled reactor was used to study biomass combustion under conditions typical of the suspension-burning phase in a spreader-stoker-fired boiler. Isothermal combustion data and nitric oxide (NO) emission rates were obtained as a function of temperature, local oxygen concentration, and vertical velocity for sized biomass fuels. Two softwoods, a hardwood, and a North Carolina peat were studied.
The pyrolytic C, H, and N data confirmed the overall high volatility, relative to coal, of these biomass fuels. Particulate emissions were correlated to vertical velocity and particle geometry, but were found to be relatively insensitive to combustion-zone oxygen, temperature, and biomass composition, NO emissions are strongly dependent on combustion-zone oxygen concentration and the nitrogen content of the biomass fuel. NO emissions increased dramatically with increasing excess air and increasing fuel nitrogen; however, these emissions were relatively insensitive to both temperature and moisture content.
Lemieux, P.M.; Silcox, G.D.
and Pershing, D.W.
Waste Management, 9:125-137, 1989. Funded by Westinghouse Corp.
Previous experimental studies have indicated that rotary kilns may be suitable combustion systems to incinerate small quantities of off grade zirconium sponge produced during the manufacturing of zirconium for the nuclear industry. This paper describes a mathematical model of zirconium sponge combustion in a rotary kiln environment and specifically examines the use of the bed submodel to analyze detailed zirconium combustion data obtained previously in a rotary kiln simulator. The results of this analysis indicated that the experimentally observed burning rates could be predicted within 25% based on available transport correlations and current understanding of zirconium combustion. Without any adjustment of the physical parameters in the model, both the experimental results and the model predictions indicated that the primary combustion parameters are the bulk oxygen concentration within the kin and the local kiln bed temperature. Charge size was found to be less significant. A detailed analysis of the theoretical predictions indicates that the zirconium sponge oxidation rate is controlled by three sequential processes (the convection of oxygen from the bulk gas to the top of the bed, the diffusion of oxygen through the bed to the particle surface, and the diffusion of oxygen through previously formed zirconium dioxide product to the unreacted zirconium metal). Under conditions typical of commercial rotary kiln operation all three of these resistances appear to be significant. Both the experimental data and the model suggest that intrinsic chemical kinetics are fast and not controlling except during the first few minutes after the zirconium is charges. The model assumes that the zirconium oxide product layer increases until it reaches a maximum value after which it remains constant due to continuous formation and abrasion.
Boardman, R.D.; Smoot, L.D.
and Brewster, B.S.
Western States Section, The Combustion Institute, Livermore, California,
1989. Funded by US Department of Energy through subcontract from Advanced Fuel
Research Co., and ACERC (National Science Foundation and Associates and Affiliates).
A generalized NOx model is being developed to predict nitric oxide formation in practical combustors. The NOx model incorporates an extended global fuel-NO mechanism and the modified Zeldovich mechanism to predict thermal NO formation. The importance of coupling turbulence with the chemical kinetics for practical combustors is addressed. Thermal NO data for a turbulent gaseous diffusion flame (in a laboratory-scale furnace) are presented. The model is being validated using these previously unpublished data and other pulverized-coal combustion and gasification data from the literature.
Meuzelaar, H.L.C.; McClennen,
W.H.; Arnold, N.S.; Maswadeh, W.; Reynolds, T.K.; Urban, D.T. and Jones, P.R.
Proc. 37th ASMS Conference on Mass Spectrometry and Allied Topics, Miami
Beach, Florida, 1424-1426, 1989. Funded by ACERC (National Science Foundation
and Associates and Affiliates), the State of Utah, US Department of Energy,
the Department of Defense Chemical Research Development and Engineering Center
and Finnigan-MAT Corp.
The objective of the work reported here is to develop a compact, mobile mass spectrometer with EI, CI and MSn capabilities. Moreover, the mobile MS system should be capable of analyzing gases, vapors and aerosols in air at low ppb levels while allowing positive identification of individual components in complex mixtures. In view of the size and weight restrictions inherent in the mobility requirement, a special miniaturized version of the Finnigan MAT Ion Trap Mass Spectrometer (ITMS?) was constructed in close collaboration with the manufacturer. This MINITMASS Miniaturized Ion Trap Mass Spectrometer) system is equipped with automatic gain control, automatic reaction control, selective mass storage and axial modulation options, in addition to the required EI/CI and MSn operating modes. The 2x2x2 ft MINITMASS module is mounted within a 6 ft high mobile rack together with all gas supplies, pumps, inlet controls and a PC 80386 workstation. The entire system requires approx. 1000 W of ac power. A 6x7x8 ft, self-contained mobile laboratory module, which fits on a standard 3/4 ton pick-up truck, enables operation of the MINITMASS in remote locations and rugged terrain. Also, the MINITMASS system can be remotely controlled from a distance up to several miles using a second PC workstation, and Carbon Copy© software. A direct air-sampling inlet enables repetitive collection of 10-50 microliter air samples at 15-60 sec intervals. Use of "transfer line chromatography" provides additional resolution and specificity for complex mixtures. Minimum detectable levels of gases and vapors in air are in the low to medium ppb range without the use of concentration devices. Alternatively, a special automated inlet enables electrostatic precipitation of air particulate matter on a ferromagnetic filament with subsequent analysis by Curie-point pyrolysis (GC)/MSn. The system has been successfully operated in the desert (at temperatures up to 100 F), as well as under a variety of indoor conditions, e.g., for monitoring laboratory-scale combustion reactors.
Arnold, N.S.; Roberts, K.A.;
McClennen, W.H. and Meuzelaar, H.L.C.
Proc. 37th ASMS Conference on Mass Spectrometry and Allied Topics, Miami
Beach, Florida, 1424-1426, 1989. Funded by ACERC (National Science Foundation
and Associates and Affiliates), the State of Utah, US Department of Energy,
the Department of Defense Chemical Research Development and Engineering Center
and Finnigan-MAT Corp.
A direct atmospheric vapor sampling inlet has been used for on-line monitoring of vapors in laboratory scale reactors. The inlet consists of three concentric tubes with appropriate flow control plumbing and electronics. This inlet provides for direct introduction of a pulse of air (.5 to 2 s) into a short (1 m) coated fused silica capillary column enclosed in the heated transfer line housing of a Finnigan-MAT ITD. Effluent from the column emerges directly into the ion trap. Data presented here were obtained by sampling from a bed-characterization reactor (for waste disposal studies) using the MINITMASS, a modified mobile Ion Trap Mass Spectrometer. (Alternate sampling environments have included a coal combustor, an open air chemical release, a micro-scale laser pyrolysis chamber, and in-building ambient atmospheres.) Vapor samples were obtained repetitively at 60 s intervals, allowing for an isothermal GC separation of various components. A ~1.5 s vapor sample allowed up to 100 ul (@STP) of reactor atmosphere to enter the transfer line for chromatographic separation. A .18 mm ID transfer line with a .4 um DB-5 coating (J+W Scientific) was operated isothermally at either 25º, 80º or 125ºC. Carrier gas (helium) velocity was -2.7 m/s (at column temp=25ºC and 4400 ft elevation). All analyses were performed using electron impact ionization. Detection limits have been established near the 1 ppb level for various substituted aromatic compounds using this (MINITMASS) system and taking advantage of the Axial Modulation* and Selective Mass Storage* features to improve sensitivity. Estimations of concentration in this presentation are provided from the calibration data obtained on toluene, ethylbenzene, o-, m-, and p-xylene and general sensitivity characteristics of ion trap mass spectrometers for the compounds of interest. In the present analyses, halogen-, nitrogen- and oxygen-substituted aromatics have been detected at <100 ppb. Various column temperatures allowed for analysis of compounds with atmospheric boiling points from 80ºC (benzene) to 350ºC (anthracene) present in reactor vapors. To date, test analyses of high boiling compounds than these have required the reactor be run under nitrogen to prevent rapid column degradation, though compounds as involatile as dibenzanthracenes (bp 550ºC) have been detected under test conditions.
Arnold, N.S.; McClennen,
W.H.; Maswadeh, W.; Urban, D.T.; Reynolds, T.K.; Jones, P.R. and Meuzelaar,
H.L.C.
Proceedings of the 1989 U.S. Army Chemical Research Development and Engineering
Center Scientific Conference on Chemical Defense Research, 1989. Funded
by ACERC (National Science Foundation and Associates and Affiliates), the State
of Utah, US Department of Energy, the Department of Defense Chemical Research
Development and Engineering Center, Geocenter, Inc. and Finnigan-MAT Corp.
A fieldable, Miniaturized Ion Trap Mass Spectrometer (MINITMASS) was constructed for tandem mass spectrometry of environmental vapors. Furthermore, a vapor sampling inlet for transfer line gas chromatography/mass spectrometry was developed which permits direct on-column introduction of atmospheric vapor samples. The transfer line gas chromatography/tandem mass spectrometry combination provided for direct introduction of complex vapor samples with short overall analysis times for on-line monitoring of changing environmental conditions. Work to date has shown the capability for low ppb analysis of substituted aromatic hydrocarbons, corresponding to subpicogram quantities per compound, in MS as well as MS/MS mode.
Arnold, N.S.; McClennen,
W.H. and Meuzelaar, H.L.C.
Preprints of Papers Presented at the 198th ACS National Meeting, 29 (2),Miami
Beach, Florida, 1989. Funded by ACERC (National Science Foundation and Associates
and Affiliates), the State of Utah, US Department of Energy, the Department
of Defense Chemical Research Development and Engineering Research Center and
Finnigan-MAT Corp.
An air-sampling inlet has been developed for on-column injection of atmospheric vapor samples using transfer line GC/MS analysis. Repetitive sampling at 15 to 60 sec intervals provides for short GC separations of the individual components. On-site GC/MSn analyses have been performed using a modified mobile ion trap mass spectrometer. Sites sampled thus far include a laboratory scale coal combustor, a high temperature soil desorber for hazardous waste disposal studies, an open-air chemical release and in-building ambient atmospheres.
Current detection limits are on the order of 1 ppb for selected compounds. Compounds with boiling points greater than 80ºC (e.g., benzene) can be readily separated with a 1 m DB-5 coated fused silica column. Analyses reported here are primarily aimed at aromatics through benzopyrene including nitrogen-, oxygen- and halogen-substituted compounds.
Meuzelaar, H.L.C.; Arnold,
N.S.; McClennen, W.H. and Snyder, A.P.
Proceedings of the 1989 US Army Chemical Research Development and Engineering
Center Scientific Conference on Chemical Defense Research, 1989. Funded
by ACERC (National Science Foundation Associates and Affiliates), the State
of Utah, US Department of Energy, the Department of Defense Chemical Research
Development and Engineering Center and Finnigan-MAT Corp.
A novel direct vapor-sampling inlet has been tested in combination with Transfer line Gas Chromatography/Mass spectrometry (TLGC/MSn) using the MINITMASS (Miniaturized Ion Trap Mass Spectrometer) system developed at the University of Utah. Typically, 0.2-0.5 s wide air pulses are injected into the 1 m long transfer line at 15-60 s intervals. Even with relatively complex mixtures of vapors, e.g., produced by desorption and combustion of model compounds in a laboratory-scale fixed bed reactor, sufficient GC separation may be obtained to allow positive identification of minor reaction products by direct library search and matching procedures. Moreover, the high sensitivity of the MINITMASS allows tandem MS analysis of subpicogram quantities of selected model compounds.
Meuzelaar, H.L.C.; Arnold,
N.S.; McClennen, W.H. and Maswadeh, W.
Conference on Environmental Chemistry, Jeckyll Island, Georgia, 1989.
Funded by ACERC (National Science Foundation Associates and Affiliates), the
State of Utah, US Department of Energy, the Department of Defense Chemical Research
Development and Engineering Center, Geocenter, Inc. and Finnigan-MAT Corp.
Recent advances in Ion Trap/Mass Spectrometry (ITMS) technology now enable the assembly of compact ITMS systems with Chemical Ionization (CI) as well as tandem MS (MSn) capabilities. In combination with the proven high sensitivity (full spectra have been recorded on less than 1 pg of sample) and the favorable vacuum characteristics, ITMS devices appear especially well suited for a variety of environmental monitoring tasks.
Based on these assessments, we undertook the development of a mobile Miniaturized Ion Trap Mass Spectrometer (MINITMASS) equipped with specialized air sampling inlets for gases/vapors as well as for aerosols. Both inlet systems employ the so-called transfer line chromatography (TLGC) approach in order to increase specificity and minimize exposure of transfer line, ion source and electron multiplier to oxygen.
Gases and vapors are sampled as 1-2 sec wide air "pulses" at 15-60 second intervals depending on the degree of chromatographic separation required. Minimum detectable concentration levels were found in the low to medium ppb range. The aerosol inlet uses electrostatic precipitation of aerosol particles (0.5-5 um range) on a ferromagnetic filament. After a preselected collection period (e.g., 1-10 minutes) the filament is automatically inserted into a Curie-point pyrolysis reactor with subsequent production of the pyrolysis GC/MS patterns of the collected aerosol particles.
Thus far, the system has been tested with synthetic polymers, biopolymers and bacterial spores.
Lighty, J.S.; Eddings, E.G.;
Deng, X.-X.; VanOs, L.M. and Pershing, D.W.
82nd Annual Air and Waste Management Association Annual Meeting, Anaheim,
California, 1989. Funded by the Gas Research Institute, Dave Linz, Project Manager,
ACERC (National Science Foundation and Associates and Affiliates), the State
of Utah, and US Department of Energy.
Thermal treatment is a proven, permanent destruction technology for most organic wastes and is presently available commercially. Rotary kiln incineration is one of the most common systems for thermal remediation of solids; however, new thermal technologies are being sought. The EPA Superfund Innovative Technology Evaluation (SITE) Program, which focuses on the use of innovative technologies for permanent remediation purposes, has identified seven thermal technologies that have been or will be demonstrated this has identified seven thermal technologies that have been or will be demonstrated this year. These technologies include infrared thermal destruction, circulating fluidized bed combustion, and in situ steam/air stripping. In each of these technologies important transport phenomena, specifically mass and heat transfer, must be understood to enable performance prediction, through modeling, for these technologies as full-scale processes.
The program at the University of Utah attempts to identify the fundamental transport rates in the decontamination of solids using thermal treatment. Once these phenomena are understood, the thermal treatment system can then be optimized. The experimental approach involves three fundamental rate reactors and two reactors designed specifically to address incineration in a rotary kiln environment. The fundamental experiments attempt to address incineration in a rotary kiln environment. The fundamental experiments attempt to identify the controlling processes at a particle level in a Particle-Characterization Reactor (PCR) and the resistances within a bed of solid in two Bed-Characterization Reactors (BCR). The fundamental insights gained from these reactors can be applied to any thermal treatment system, since the systems differ only in the mechanisms of heat transfer and mass treatment system, since the systems differ only in the mechanisms of heat transfer and mass transfer. For example, in infrared thermal destruction the transport limitations within the bed and radiation from the top of the bed are important processes that need to be understood. In a circulating fluidized bed combustor, an understanding of gas/solid contacting and convection needs to be gained. In situ steam/air stripping requires knowledge of the interactions between the water, contaminant, and soil matrix.
Two other experimental systems focus specifically on the unique features of rotary-kiln incineration technology. An ambient temperature mixing reactor and a rotary kiln simulator are used to evaluate mixing and combustion characteristics typical of a large-scale rotary kiln.
The paper focuses on results obtained in the Bed-Characterization Reactors. Mass transfer and heat transfer resistances have been found to be extremely important. The effects of packing density, moisture, and particle size on these resistances will be discussed.
McClennen, W.H.; Arnold,
N.S.; Lighty, J.S.; Eddings, E.G.; Lindgren, E.R.; Roberts, K.A. and Meuzelaar,
H.L.C.
Preprints of Papers Presented at the 198th ACS National Meeting, 34 (3),
Miami Beach, Florida, 1989. Funded by the Gas Research Institute, Dave Linz,
Project Manager, ACERC (National Science Foundation and Associates and Affiliates),
the State of Utah, and US Department of Energy.
Incineration is an effective technology for the remediation of organic chemical contaminated wastes. For solid wastes, such as contaminated soils, processes involving separate stages of a primary desorber and secondary afterburner are particularly useful. The desorption stage is currently being modeled using a particle-characterization reactor (PCR, 0-500 g capacity), a bed-characterization reactor (BCR, 0.5-5 kg), and a rotary kiln simulator (2-15 kg) to study fundamental processes such as mass transfer, heat transfer, and volatilization of contaminants. This paper describes the analytical methods and preliminary results from monitoring the evolution of organic compounds in these and smaller reactors.
The samples are soil contaminated with a broad range of polynuclear aromatic (PNA) hydrocarbons such as those derived from coal tars. The analytical methods primarily involve mass spectrometry (MS) with a variety of sample introduction techniques. The on-going analyses include solvent and thermal extractions of soil before and after various thermal treatments as well as on-line monitoring of vapors during desorption.
Cundy, V.A.; Lester, T.W.;
Conway, L.R.; Jakway, A.J.; Leger, C.B.; Montestruc, A.N.; Acharya, S.; Sterling,
A.M.; Owens, W.D.; Lighty, J.S.; Pershing, D.W. and Silcox, G.D.
Louisiana State University/Hazardous Waste Research Center SAC Review Meeting,
Baton Rouge, Louisiana, 1989. Funded by Louisiana State University/Hazardous
Waste Research Center (Supported by US Environmental Protection Agency).
A comprehensive study aimed at understanding rotary kiln performance is underway. The program is led by personnel from Louisiana State University. Bench and pilot-scale facilities at the University of Utah are available for use in solids desorption studies. Full-scale in situ measurements are obtained from the Louisiana Division rotary kiln facility of Dow Chemical USA, located in Plaquemine, Louisiana. This paper presents a summary of the project providing some detail of the work that has been accomplished from 1 January through 31 August 1989.
McClennen, W.H.; Arnold,
N.S.; Roberts, K.A.; Meuzelaar, H.L.C.; Lighty, J.S. and Lindgren, E.R.
1st International Congress on Toxic Combustion, 1989. Funded by Remediation
Technologies, the Gas Research Institute, ACERC (National Science Foundation
and Associates and Affiliates), the State of Utah, and US Department of Energy.
A system for on-line analysis of organic vapors by short column gas chromatography/mass spectrometry (CG/MS) has been used to monitor products from a thermal soil desorption reactor. The system consists of a unique air-sampling inlet with a 1 meter long capillary column coupled directly to a modified Ion Trap Mass Spectrometer (Finnigan MAT) with demonstrated detection limits for alkylbenzenes in the low ppb range. In this work the mobile instrument is used for repetitive GC/MS and GC/MSn (tandem MS) analysis at 30 to 60 sec intervals of PAH products from coal tar contaminated soils in a bed characterization reactor.
Results for naphthalene through dibenzanthracenes are compared to conventional, more detailed GC/MS analyses of extracts from the soil before and after thermal treatment.
Lighty, J.S.; Gordon, D.L.;
Pershing, D.W.; Owens, W.D.; Cundy, V.A. and Leger, C.B.
Stationary NOx Symposium, San Francisco, California,
1989. Funded by Louisiana State University/Hazardous Waste Research Center,
and ACERC (National Science Foundation and Associates and Affiliates).
While fuel NOx formation has been extensively studied for coal combustion, little information is available on NOx formation for nitrogenous waste constituents. These wastes, usually destroyed in hazardous-waste incinerators, are prevalent and exist as solids (plastics, nylongs) or liquids (dyes, process waste).
Results are presented from studies conducted in a scaled, batch rotary-kiln simulator. Constituent parameters, i.e. constituent type and percent fuel nitrogen, were studied at 730ºC. Sorbent was contaminated with a variety of constituents ranging in concentrations from 0.5% to 3.0% nitrogen by weight (for 681 g charge).
NOx exhaust-gas concentrations ranged from 60-80 ppm for a base run (no fuel nitrogen) to 200-1750 ppm for a nitrogenous waste. Results inducated that, at higher concentrations, more NOx was formed, accompanied by an increase in temperature. Higher concentrations also resulted in reduced percent conversions of fuel nitrogen to NOx. Evolution for different constituents, given the same concentration, varied; aniline formed more NOx than pyridine, followed by ethylenediamine.
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