The formation and build-up of slag deposits on heat transfer surfaces is one of the most serious problems in pulverized coal combustion. This phenomenon, traditionally called wall slagging, is known to cause undesirable effects on heat... more
The formation and build-up of slag deposits on heat transfer surfaces is one of the most serious problems in pulverized coal combustion. This phenomenon, traditionally called wall slagging, is known to cause undesirable effects on heat and mass transfer and in some instances induce corrosion. What is believed to be a major mechanism for the production of slag is the formation of low melting eutectic compounds in the post combustion region, many of which will stick to the heat transfer surface. The composition of this slag may very well change during operation as layers of the slaggy material build up or break off. An understanding of the chemical composition of such slags under boiler operating conditions and as a function of the mineral composition of various coals is the ultimate goal of this program. The principal constituents in the ash of many coals are the oxides of Si, Al, Fe, Ca, K, S, and Na. The analytical method required must be able to determine the functional forms of all of these elements both in coal and in coal ash at elevated temperatures. One unique way of conducting these analyses is by x-ray spectroscopy. The experiment involves scanning through the K- or L-shell absorption edge of the element in question. The structure of the absorption edge, consisting of transitions to unoccupied molecular levels, can be compared to those of model compounds for identification. The relative position of the absorption edge can yield information regarding the oxidation state of the element. This portion is the XANES portion of the spectrum. The EXAFS region, extending from about eV above the absorption edge, represents scattering from neighboring constituents and can be used to determine the coordination number and coordination distance of a specific element from its neighboring atoms.
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Modeling of pyrolysis and Boudouard reactions of various coals, biomasses and coal-biomass blends using thermogravimetric analysis, experimental moving bed gasification system and stable carbon isotope ratio mass spectroscopy Abhijit... more
Modeling of pyrolysis and Boudouard reactions of various coals, biomasses and coal-biomass blends using thermogravimetric analysis, experimental moving bed gasification system and stable carbon isotope ratio mass spectroscopy Abhijit Bhagavatula1, Naresh Shah2, Gerald Huffman2 Christopher Romanek3 1. Corresponding author: Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY, 40506-0043, USA email: abh222@uky.edu, abhijitbv@gmail.com 2. Department of Chemical and Materials Engineering, University of Kentucky, 533 S.Limestone St, Suite 107, Whalen Building, Lexington, KY, 40506-0043, USA 3. Department of Earth and Environmental Sciences, University of Kentucky, 216 Slone Building, Lexington, KY, 40506-0053, USA Abstract Non-isothermal thermogravimetric analysis has been performed at different heating rates of 5, 10, 20 and 40 C/min to investigate the thermal decomposition kinetics of two coals: lignite and sub-bituminous; four biomass materials: pine...
A new process has been developed for the conversion of waste plastic to lubricating base oil. It has also been demonstrated that waste plastic and Fischer−Tropsch (FT) wax can be co-processed to produce lube range molecules. The process... more
A new process has been developed for the conversion of waste plastic to lubricating base oil. It has also been demonstrated that waste plastic and Fischer−Tropsch (FT) wax can be co-processed to produce lube range molecules. The process uses a thermal, ...
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Research Interests:
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ABSTRACT This article demonstrates that energy-filtered transmission electron microscopy (EFTEM) can be a valuable tool for the identification and analysis of nanometer-sized airborne particles. Ambient airborne particulate matter (PM)... more
ABSTRACT This article demonstrates that energy-filtered transmission electron microscopy (EFTEM) can be a valuable tool for the identification and analysis of nanometer-sized airborne particles. Ambient airborne particulate matter (PM) samples collected at Lexington, Kentucky were investigated using EFTEM in combination with electron energy-loss spectroscopy (EELS), energy-dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM). EFTEM provides a fast and convenient way to map the distribution of carbonaceous aggregates, which constitute a significant fraction of the samples. Sulfur-bearing particles are common in the submicron inorganic fraction. Sulfur elemental maps were obtained from some sulfur-bearing particles, and the oxidation state of sulfur was revealed to be primarily S(VI) as sulfate from the electron energy-loss near-edge fine structures of the sulfur L-edge. Other types of inorganic particles, such as silicon-bearing particles and transition metal oxides, were also observed in the samples and their chemical composition, crystalline phase, and microstructures were studied by using the techniques listed above. The use of EFTEM for the study of airborne PM is in its infancy, but it will undoubtedly gain increased attention for the characterization of individual particles of environmental concern, especially those that contain transition metal compounds and ultrafine carbonaceous particles, which may both have adverse effects on human health.
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Stacked cone carbon nanotubes (SC-CNT) with a BET surface area of 280 m 2 /g were used as the support medium to prepare Pt catalysts for partial dehydrogenation of tetralin and decalin to produce pure hydrogen and naphthalene. The results... more
Stacked cone carbon nanotubes (SC-CNT) with a BET surface area of 280 m 2 /g were used as the support medium to prepare Pt catalysts for partial dehydrogenation of tetralin and decalin to produce pure hydrogen and naphthalene. The results show that for dehydrogenation of ...
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Traditionally, hydrogen is produced by reforming or partial oxidation of methane to produce synthesis gas, followed by the water-gas shift reaction to convert CO to CO 2 and produce more hydrogen, followed in turn by a purification or... more
Traditionally, hydrogen is produced by reforming or partial oxidation of methane to produce synthesis gas, followed by the water-gas shift reaction to convert CO to CO 2 and produce more hydrogen, followed in turn by a purification or separation procedure. This paper presents ...
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Soot is a chemically and structurally very complex carbon material with adverse impact on human health and climate. Our Consortium has been looking at the carbon in soot from the environmental perspective since 2001. First experiments... more
Soot is a chemically and structurally very complex carbon material with adverse impact on human health and climate. Our Consortium has been looking at the carbon in soot from the environmental perspective since 2001. First experiments were done on diesel soot (DEP), where we paid also attention to the nature of extracts, atmospheric chemistry, radiation damages and to TEM-EELS [1-6]. Efforts were made to understand the influence of diesel engine operation parameters and fuel additives to soot structure [7-9]. With these fundamental studies the methodical foundations were laid to quantitatively distinguish in ambient particulate matter diesel engine soot from biomass wood smoke (WS) [10,11] and to formulate a simple semi-quantitative model for the atmospheric weathering and ageing of particulate matter (PM) [12]. The merit of this NEXAFS technique for thorough understanding of soot formation and soot interactions has now been recognized in environmental sciences [13]. Current studies...
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Coal combustion is generally viewed as a major source of PM2.5 emissions into the atmosphere. For some time, toxicologists have been asking for an exposure environment enriched with the coal combustion source specific PM{sub 2.5} to... more
Coal combustion is generally viewed as a major source of PM2.5 emissions into the atmosphere. For some time, toxicologists have been asking for an exposure environment enriched with the coal combustion source specific PM{sub 2.5} to conduct meaningful exposure ...
The formation and build-up of slag deposits on heat transfer surfaces is one of the most serious problems in pulverized coal combustion. This phenomenon, traditionally called wall slagging, is known to cause undesirable effects on heat... more
The formation and build-up of slag deposits on heat transfer surfaces is one of the most serious problems in pulverized coal combustion. This phenomenon, traditionally called wall slagging, is known to cause undesirable effects on heat and mass transfer and in some instances induce corrosion. What is believed to be a major mechanism for the production of slag is the formation of low melting eutectic compounds in the post combustion region, many of which will stick to the heat transfer surface. The composition of this slag may very well change during operation as layers of the slaggy material build up or break off. An understanding of the chemical composition of such slags under boiler operating conditions and as a function of the mineral composition of various coals is the ultimate goal of this program. The principal constituents in the ash of many coals are the oxides of Si, Al, Fe, Ca, K, S, and Na. The analytical method required must be able to determine the functional forms of all of these elements both in coal and in coal ash at elevated temperatures. One unique way of conducting these analyses is by x-ray spectroscopy. The experiment involves scanning through the K- or L-shell absorption edge of the element in question. The structure of the absorption edge, consisting of transitions to unoccupied molecular levels, can be compared to those of model compounds for identification. The relative position of the absorption edge can yield information regarding the oxidation state of the element. This portion is the XANES portion of the spectrum. The EXAFS region, extending from about eV above the absorption edge, represents scattering from neighboring constituents and can be used to determine the coordination number and coordination distance of a specific element from its neighboring atoms.
Research Interests:
TOXIC SUBSTANCES FROM COAL COMBUSTION -- A COMPREHENSIVE ASSESSMENT Quarterly Technical Report Reporting Period: 10/01/1996 - 12/31/1996 Authors: LE Bool III; CL Senior; F. Huggins; GP Huffman; N. Shah; JOL Wendt; TW Peterson; AF Sarofim;... more
TOXIC SUBSTANCES FROM COAL COMBUSTION -- A COMPREHENSIVE ASSESSMENT Quarterly Technical Report Reporting Period: 10/01/1996 - 12/31/1996 Authors: LE Bool III; CL Senior; F. Huggins; GP Huffman; N. Shah; JOL Wendt; TW Peterson; AF Sarofim; I. Olmez ...
Research Interests: Carbon Dioxide, Trace Metals, Regional development, Power Plant, Carbon Monoxide, and 15 morePower Generation, Cooling Rate, Data Collection, Iron, Fly Ash, Theoretical Analysis, North Dakota, Low Temperature, Plant Development, Electric Power, Trace element, Large Scale, Experimental Data, Clean Air Act, and Packed Bed
TOXIC SUBSTANCES FROM COAL COMBUSTION -- A COMPREHENSIVE ASSESSMENT Quarterly Technical Report Reporting Period: 10/01/1996 - 12/31/1996 Authors: LE Bool III; CL Senior; F. Huggins; GP Huffman; N. Shah; JOL Wendt; TW Peterson; AF Sarofim;... more
TOXIC SUBSTANCES FROM COAL COMBUSTION -- A COMPREHENSIVE ASSESSMENT Quarterly Technical Report Reporting Period: 10/01/1996 - 12/31/1996 Authors: LE Bool III; CL Senior; F. Huggins; GP Huffman; N. Shah; JOL Wendt; TW Peterson; AF Sarofim; I. Olmez ...