ACERC
Abstracts - 1996 |
ACERC
Abstracts - 1996 |
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Thrust Area 3: Pollutant Formation/Control and Waste Incineration |
Gao, D.-C.
Temperature and
the Fate of Heavy Metals During the Incineration of Solid Hazardous Waste in
Rotary Kilns, Ph.D./U of U, 1996. Advisor: Silcox
Veranth, J.M.; Gao, D.-C.
and Silcox, G.D.
ES&T, 30:3053-3060, 1996. Funded by ACERC and Gas Research Institute.
Gas and bed temperatures were studied in a 4.4 m by 12 m, co-current flow, slagging rotary kiln at a commercial hazardous waste incinerator. The visual observations used by the kiln operators to control the process are described. These observations were quantified using thermocouples, radiation pyrometers, and phase-change indicators. The objectives were to estimate the peak bed temperature and compare this to measurements at the kiln exit. The maximum bed temperature occurs toward the middle of this type of kiln and not at the discharge. The slag melting temperature and test pellets with known melting points indicate that the peak bed temperature can be 100-300 K higher than the kiln exit temperature reported by the permanent instruments at this facility. Both broadband radiation pyrometers and thermocouples give a qualitative temperature indication that can be used for process control, but the readings depend on the sensor locations relative to the incompletely mixed air and combustion products. Two-color radiation pyrometer measurements of surface temperature near the kiln exit are higher than the actual temperature due to reflected radiation.
Snyder, A.P.; Thornton,
S.; Dworzanski, J.P. and Meuzelaar, H.L.C.
Field Analytical Chemistry and Technology, 1:49-58, 1996. Funded by US
Army Research Office.
The absence of a field-portable device to provide real-time detection of Gram-positive bacterial spores has prompted the interfacing of a pyrolysis (Py) module to an existing, hand-held gas-chromatography-ion-mobility spectrometry (GC/IMS) device. In this configuration, spore detection is achieved by the observation of picolinic (2-pyridinecarboxylic) acid (PA), which is the most characteristic pyrolysis decomposition product of the parent dipicolinic (2,6-pyridinedicarboxylic) acid (DPA). Positive identification of PA was demonstrated using a laboratory-based GC instrument with dual, parallel mass spectrometry (MS) and IMS detectors. Spores and vegetative microorganisms of the genus Bacillus were characterized by the presence and absence of DPA, respectively, and the picolinic acid marker was identified from the GC/IMS and GC/MS profiles. A field-portable prototype Py-GC/IMS system is described and appears to provide similar bioanalytical information with respect to the laboratory-based system. Preliminary results of this study indicate that the degree of compound separation afforded by a short GC capillary column guards against common environmental interferences including urban particulate matter and biological particles such as fungal spores and pollen.
McClennen, W.H.; Vaughn,
C.L.; Cole, P.A.; Sheya, S.A.N.; Wager, D.J.; Mott, T.J.; Dworzanski, J.P.;
Meuzelaar, H.L.C. and Arnold, N.S.
Field Analytical Chemistry and Technology, 1(2):109-116, 1996. Funded
by Hewlett Packard and ACERC.
Obtaining representative VOC (volatile organic compound) measurements in ambient environments that exhibit complex concentration gradients and/or trends is difficult when relying upon limited numbers of analyses obtained by simple pooling or averaging techniques. A more effective approach is to perform large numbers of analyses over a period of time to permit detailed mapping of profiling of local gradients and trends. Until recently, use of GC/MS (gas chromatography/mass spectrometry) techniques for rapid profiling or mapping operations was not feasible because of sample speed limitations. This article describes a roving GC/MS system based on the combination of a Hewlett-Packard model 5972 MSD (mass selective detector), a FemtoScan Enviroprobe repetitive vapor sampling inlet with short capillary GC column, and Alcatel Micro HV oil-less vacuum pump stack and a Pentium notebook PC running under Windows 95. The roving system is further equipped with differential GPS (global positioning system) and radio transceiver capabilities thereby permitting remote tracking of vehicle location and local VOC concentrations. Laboratory tests demonstrate lower detection limits of approx 4 ppb for BTX (benzene, toluene, and zylene), corresponding to minimum detectable quantities of a mixture of volatile ketones. Demonstrated outdoor performance, using a zero-emission electric vehicle, includes measurement of low ppb BTX levels along a 6 km urban route at 15 s (~ 150 m) intervals while moving at an estimated average speed of 35 km/hr. Indoor measurements of toluene concentrations in the low to mid ppm range at 6 s (~5 cm) intervals along a 6 m long path reveal a high degree of spatial and temporal variability in VOC concentrations. Mobility, specificity, sensitivity and speed of the roving GC/MS method make this a promising candidate method for rapid outdoor and indoor screening, monitoring and mapping of VOCs.
Brewster, B.S.; Smoot, L.D.
and Barthelson, S.H.
Energy & Fuels, 9:870-878, 1996. Funded by ACERC.
Predictions of a two-dimensional, axisymmetric combustion model, using various devolatilization submodel options, are compared with new experimental data from a near-laminar, drop-tube furnace. Included in the devolatilization submodels that were teste are the commonly used empirical one-and two-step models and a chemical, coal network model with parameters based on coal structure. The goals of this work were to evaluate the latter approach as compared with the simple, empirical approach usually used in such calculations and to assess the role of turbulence in a near-laminar reacting flow. Comparisons were made for carbon conversion, radially averaged oxygen and near-effluent NOX concentrations, for a range of coal types and equivalence ratios. The predictions quantify an ignition delay that is consistent with the measurements. Computations with the fundamental, chemical devolatilization submodel gave superior predictions of mass loss when the coal type was within the interpolation range of the submodel parameter database. Accuracy declined significantly when the coal type was outside the interpolation range. Inclusion of the effects of turbulence was required to account for the observations. Near effluent NO predictions with the chemical submodel agreed with measured NOX values to within an average of about 20 percent.
Pershing, D.W.; Lighty,
J.S.; Harding, S.N.; Brouwer, J.; Heap, M.P.; Munro, J.M. and Winter, R.M.
Proceedings from the Finnish-Swedish Flame Days, Naantali, Finland, September,
1996. Funded by Environmental Protection Agency, US Department of Energy and
National Science Foundation.
Biomass fuels account for a significant fraction of the worldwide energy usage. In 1990 consumption is believed to have exceeded 13 quads according to Tillman (1991). This does not include the combustion of peat that is known to be widely used in some northern European countries and in parts of the former Soviet Union. Biomass energy consumption is also a significant fraction of total energy usage in many developing nations. Hence, emissions from combustion of biofuels are of interest to the environmental community.
Most biomass materials generally produce lower NOx emissions when they are burned than their fossil fuel counterparts, but under certain conditions NOx emissions can be significant. Biomass fuels usually contain relatively limited amounts of organic nitrogen (often 0.1 ± 0.1%) so NOx formation from fuel nitrogen is generally small (except in the case of peat and some plant wastes). Biofuels also tend to burn at cooler combustion temperatures (due to higher moisture contents and the presence of oxygen in the fuel structure), which tends to minimize the formation of NOx by the thermal mechanism (the high temperature fixation of N2 in the combustion air).
The purpose of this paper is review the available information on the formation and the control of NOx emissions during the combustion of biofuels alone and in combination with fossil fuels and/or wastes. Both laboratory and pilot scale studies have been included, as well as full scale field test results where they are generally available.
Arnold, N.S.; Du, W.H.;
Sheya, S.A.N.; Mihamou, H.; Dworzanski, J.P.; Hall, D.L.; McClennen, W.H. and
Meuzelaar, H.L.C.
Proceedings of the Ninth International Symposium On Field Screening Methods
for Hazardous Wastes and Toxic Chemicals, 2:903-910, 1996. Funded by ACERC,
US Army Electrical Research Development and Engineering Center.
In recent years, a man-portable gas chromatography/mass spectrometry (GC/MS) system has been developed based on a Hewlett-Packard 5971 MSD and a unique automated vapor sampling (AVS) transfer-line (TL) GC system for direct sampling of ambient chemical vapors [1,2]. The vacuum system and power supplies were replaced to facilitate operation on 24 V DC batteries for up to 4 hours after startup on a transportable docking station. The gas chromatography was performed on a short (2 m) capillary column under isothermal conditions in a small oven to minimize power usage. Repetitive samples were taken at 10 to 60 s intervals using an automated vapor-sampling inlet.
In initial testing, the prototype system has been used for monitoring of gasoline vapors. Ambient levels of 6.0 ppm benzene, 4.1 ppm toluene, 0.22 ppm ethylbenzene, 1.1 ppm m-and p-xylene and 0.25 ppm 0-xylene were measured near a busy gas station. The gradient mapping or source tracking capabilities of the backpack-mounted system have also been demonstrated in tests with a simulated gasoline leak.
This paper will describe recent work to further evaluate the capabilities and limitations of the prototype system. Results will be described in terms of the practical utility of portable GC.NS for identification and quantification of unknown vapors.
Sheya, S.A.N.; Dworzanski,
J.P.; McClennen, W.H.; Meuzelaar, H.L.C. and Arnold, N.S.
Proceedings of the Ninth International Symposium On Field Screening Methods
for Hazardous Wastes and Toxic Chemicals, 1:213-220, 1996. Funded by ACERC.
Development of a potentially field-portable tandem GC (GC/GC) method involving a novel, dynamic coupling between two short capillary GC columns-each of which is independently optimizable with regard to temperature and flow-is described. The relatively slow (5-25 sec wide), GC peaks eluting from the first (1.2 m x 530 µm) column are sampled repetitively at 1-5 sec. Intervals into the second (0.8 m x 100 µm) column. Dynamic coupling by means of fluidic AVS (Automated Vapor Sampling) technology, rater than through trap-and-desorb interfaces, reduces power requirements. Further power reduction is achieved by isothermal operation of both columns. If properly designed and optimized the sensitivity of dynamic GC/GC techniques should approach that of one-dimensional GC, depending on the type of detector used. Since a universally responsive, subambient pressure, low weight and low power detector for field-portable GC/GC has not yet been found, a Hewlett Packard MSC (Mass Selective Detector) was used throughout the present study. At a maximum scan rate of 35 spectra (over 5 amu mass range), the minimum practical GC peak width eluting from the second column is limited to approximately 100 msec. The feasibility of producing comprehensive, two-dimensional chromatograms of multicomponent mixtures, volatile compounds, including C3-C6 ketones, is demonstrated.
Meuzelaar, H.L.C.; McClennen,
W.H.; Dworzanski, J.P.; Sheya, S.A.N.; Snyder, A.P.; Harden, C.S. and Arnold,
N.S.
Proceedings of the Ninth International Symposium On Field Screening Methods
for Hazardous Wastes and Toxic Chemicals, 1:38-46, 1996. Funded by ACERC,
Consortium for Fossil Fuel Liquefaction Science, US Army Electrical Research
Development and Engineering Center, Hewlett Packard, Finnigan MAT Corporation,
and Femto Scan Corporation.
The first field-portable (i.e., transportable) hyphenated analytical instruments, including commercially available MS/MS and GC/MS systems as well as a specially built GC/MS system, were introduced during the past seven years. Since then further miniaturization and ruggedization of hyphenated systems by several laboratories has resulted in fully man-portable (backpack and briefcase style) GC/MS systems and a hand portable GC/IMS prototype. The main pitfall to be avoided in developing a hyphenated, field portable system is incompatibility between the coupled techniques. Carefully designed hyphenated techniques incorporating compatible methods such as GC and MS can provide dramatic increases in resolution and chemical specificity which may be traded for speed or sensitivity gains, if needed. Novel developments currently underway in the laboratory include roving GC/MS platforms, personalized GC/IMS devices, high speed GC/GC methods and, last but not least, Virtual Reality techniques.
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