Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 494-517).

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xii, 226 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references (p. 214-225).

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / "Sponsored by: CLP Research Institute." "HKUST project no.: CLPRI02/03.EG01." Includes bibliographical references (leaves 76-83). Also available in electronic version.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1986. / Vita. Abstract. Includes bibliographical references (leaves 107-112). Also available via the Internet.

Bibliography: leaves 234-252. The devolution times of seven coals were determined by measuring the centre temperature response for single particles held stationary in a bench scale atmospheric fluidised-bed reactor.

Currently, coal combustion plays an important role in meeting the energy needs of the United States. It is expected that the effective utilization of coal will be crucial for attaining energy independence for the nation in the next 25 to 30 years, if not longer. The United States burns about 20% of the world's annual coal production, second only to China. Strikingly, there are 200-300 more years of burn at our current rate of consumption, considering our massive coal reserves. Almost half of our electricity comes from coal power. Although coal is a fossil fuel that will become more and more depleted, it will be the principal fuel for utilities in the US for decades to come. Therefore, there is a need to design new strategies to clean coal. Mercury can be found in fly ash, bottom ash, and flue gas desulfurization (FGD) material. The Hg is transferred to these coal combustion products (CCPs) from its associated parent coal. These CCPs absorb a significant amount of the Hg released during the combustion process. With the EPA's recent emphasis on controlling the Hg emission by coal-burning electric utilities, the disposal and utilization of CCPs are under an environmental microscope. As EPA regulations become more stringent, Hg concentration in CCPs is expected to increase further; i.e., more Hg will be captured in the scrubber materials. The higher Hg concentrations will have serious consequences for the management of CCPs. Systematic measurements on Hg concentrations in the feed coal and the CCPs produced from two different power plants burning Illinois coal were carried out. Not only were there substantial variations in the total Hg concentration in the parent coal from week to week from a single mine, but there were also significant variations in the weekly Hg content of the CCPs. Surprisingly, there was no linear dependence between Hg content of coal and its CCPs. No correlation was observed between Hg content of fly ash and its loss-on-ignition (LOI) values. In order to control and further understand the fate of Hg in FGD scrubber material, the following was systematically examined: (a) whether there is a strong correlation between the parent coal and the Hg captured in FGD scrubber materials, (b) the thermal behavior of Hg in parent coal, FGD gypsum, and sulfite-rich FGD material, (c) whether there is a potential of Hg re-emission during gypsum-to-hemihydrate-to-gypsum transition, and (d) how Hg behaves in sulfite-rich scrubber material at higher temperatures and pressures. Ultimately, no direct correlation between the total Hg concentration of the parent coal and its associated FGD scrubber materials was found. Mercury desorbed from FGD gypsum at relatively low temperatures (90C < T < 250C), compared to the sulfite-rich scrubber materials which released Hg continuously at ambient pressures up to 600C. However, it was found that mildly-elevated pressures immobilized Hg, even at temperatures as high as 250C. Cleaning and dewatering coal has been a major challenge. Deeper pre-combustion cleaning of ashes and clays from coals can help utilize more of Illinois coal. Efforts have been underway for decades to reduce emissions from flue gas and toxic metal reduction. Now with carbon emissions under scrutiny, the effort to maximize coal's value is more important than ever before. In most coal preparation processes, significant amounts of fines and ultrafines are generated. Because these particles are difficult to dewater, they are often discarded in waste ponds. This translates into a major economic loss for the coal industry, not only because of the fuel value lost but also the substantial economic resources required to manage coal waste ponds in an environmentally-sound manner. A new approach developed using a high intensity sonication process in recovering, cleaning, and dewatering fine/ultrafine coal particles from the waste ponds, while concurrently reducing the Hg concentration in the fine and ultrafine particles was successful. Combining sonication with vegetable oil agglomeration significantly reduced the moisture, ash, and Hg content of the cleaned, recovered coal. Differential scanning calorimetry (DSC) measurements on the recovered coal were used to understand the interaction between the coal particles, water, and oil. The results suggested that vegetable oil was effective in displacing water from the coal-water interface, with the enthalpy of the water-vapor transition of oil-agglomerated coal particles decreasing on sonication of the particles. In fact, combining sonication treatment with oil agglomeration reduced the moisture content of run-of-mine (ROM) coal and waste coal, to 6 wt% and 12 wt% respectively, and increased their loss-on-ignition (LOI) content to 91 wt% and 76 wt%, respectively. Massive quantities of synthetic gypsum are produced when the flue gases from coal burning power plants are wet scrubbed with limestone. The sulfate-rich FGD scrubber material is largely construction-quality gypsum. Because of the large production of FGD gypsum every year, the economic and environmental impetus dictates that strategies be developed to effectively utilize FGD gypsum rather than just landfill it. Beneficial uses have been found in wallboard construction and agriculture. An important aspect of this research was to evaluate whether there was potential of Hg re-emission from scrubber materials during their utilization phase. Mercury emission occurs not only with elevated temperatures but with increased time. While external pressure retards these emissions, they are not the only concern associated with CCPs. The more global, urgent problems of greenhouse gases must be resolved. The dimension of the greenhouse gases problem is daunting; according to the Energy Information Agency, nearly 6 billion metric tons of CO2 were produced in the USA in 2007, with coal-burning power plants contributing about 2 billion metric tons. The success of large-size sequestration of CO2 in coal would hinge on a thorough understanding of coal-CO2 interactions and how these interactions control the mechanical behavior of coal. Moreover, these interactions could play a crucial role in evaluating any potential risks associated with sequestering CO2 in deep, unmineable coal seams. To evaluate the risk under non-equilibrium conditions, dynamic mechanical properties of pressurized Illinois coals were measured. The results suggest that Illinois bituminous coal in its unperturbed state, i.e., when not pressurized with CO2, showed large variations in its mechanical properties. The Young's modulus varied from 0.7 GPa to 3.4 GPa even though samples were extracted from a single chunk. No glass transition was observed for any Illinois bituminous coal under ambient conditions. Upon pressurizing the Illinois bituminous coals with CO2, the DMA results showed a transition at temperatures as low as ambient. This could be a potential risk for the structural integrity of a mine if any man-made or seismic activity were present.

New advanced combined cycle coal-fired power generation systems are dependent on improvements in gas turbine technology and the development of hot gas cleaning techniques. These techniques are not only necessary to meet environmentally accepted emission limits for SOx and NOx but also to prevent downstream equipment from corrosion and erosion. Volatile alkali vapours in the exhaust gases produced by either coal gasification or combustion lead to corrosion of the gas turbine blades resulting in reduced operating life. Consequently, alkali removal systems which can operate upstream of the gas turbine have been incorporated into the development of the clean coal technologies. A number of studies on alkali removal systems have been performed in the temperature range of 800&deg;C - 1000&deg;C. Solid aluminosilicates, such as emathlite, activated bauxite, kaolinite and Fuller's Earth, react with alkali vapours at high temperatures and therefore have been characterised as suitable alkali sorbents. Fuller's Earth was identified as potentially the most suitable sorbent for use in the UK at the specified operating temperatures. This material was studied in detail by McLaughlin (1990) for use in a fixed bed configuration within the British Coal Air-Blown Gasification Cycle. Recently, it has been recognised that if ceramic filters are used for the removal of fine particulates, operating temperatures for alkali sorption will have to drop to 400&deg;C-600&deg;C, since these filters fail mechanically at higher temperatures. Much of the alkali will condense under these conditions and be removed by the filtration stages. However, the residual alkali levels may still exceed the revised turbine inlet specification of 24 ppb wt. Hence further studies of alkali sorption are required in this lower temperature region. During this work, it proved difficult to obtain accurate results at temperatures as low as 600&deg;C, because of the low level of vapour phase alkali. However, experiments were performed successfully at 650&deg;C and atmospheric pressure, on the fixed bed sorption rig used previously for tests at 827&deg;C and 927&deg;C. Tests comparing Fuller's Earth and kaolin, showed kaolin to have a higher sorption capacity at this temperature. Fixed bed tests with sodium and potassium were performed with Fuller's Earth pellets. The runs were of 200-600 hrs duration, with 4.58 ppm wt NaCl (1.8 ppm wt Na), 5 %vol H2O and up to 160 ppmv HCl in the inlet gas stream. Alkali uptake profiles were generated from chemical analysis of precise layers of pellets removed from the bed. Extensive modifications and improvements in analytical procedures enabled a closure of the mass balance of >99% to be achieved for a 600 hr run. Alkali exit levels measured using alumina wool filter pads in the exit gas were of the order of 5-6 ppb wt. Fuller's Earth pellets which had been pre-treated in gasifier gas and which were therefore contaminated with carbon, were tested and no difference was observed in their Na characteristics. Element mapping techniques based on Scanning Electron Microscopy, confirmed that a shrinking core model for Fuller's Earth grains and kaolin pellets was appropriate. The 'two-reaction' mechanism proposed by McLaughlin (1990), was used to fit the experimental results at 650&deg;C. Albite was identified by X-ray diffraction studies as the reaction product under high-acid conditions and nepheline under non-acid conditions. Exit gas analysis studies with an on-line monitor for HCl, showed the production of HCl to be directly connected with the presence of NaCl vapour and to increase significantly with the presence of water vapour in the system. However, the detailed reaction mechanism has not been identified yet. The theoretical model developed for the high temperature studies (McLaughlin, 1990), using the pellet-grain model and the 'tank-in-series' method of solution has been applied successfully at 650&deg;C. Parameters were extracted by curve fitting theoretical to experimental Na uptake concentration bed profiles. To test the numerical methods and the Szekely assumptions used in the McLaughlin program, two new computer programs were developed. The first, tested the pellet-grain model for a single pellet and the second was developed to solve the model more rigorously with a variable-order, variable-time-step numerical method. The new fixed bed model also incorporates the effects of temperature and pressure on selected parameters. It was used to predict the performance of a full-scale unit operating at 650&deg;C and 24 bara. The results indicate that a bed of Fuller's Earth pellets, 3-10 mm in diameter, 4 m long and 4 m wide can achieve exit alkali levels below 20 ppb wt in continuous operation for up to 24,000 hrs.

The major aim of this research was to provide quantitative data about the pyrolytic "behaviour of a series of coals from the South Y&gt;,ales Coalfield using thermogravimetry as the major experimental technique. It is hoped that this data will (1) provide information of value to the development of coal conversion technologies, (2) provide information about the kinetics of coal pyrolysis, (3) provide information about the effect upon the kinetic results by the addition of some transition metal elements to two of the coal samples. An extensive literature survey revealed that work of this nature had not been done previously. It was also revealed that a computer interfaced to the thermogravimetric apparatus to collect and manipulate data would aid the research. An extra aim of the research was added: to interface a i.iodel B BBC Microcomputer to the apparatus and to develop the necessary programs. This aim was successfully realised. Hot-Stage- Microscopy was used to provide qualitative information about the physical changes the samples underwent during pyrolysis. This information was used to aid the interpretation of the thermogravimetric results. Thermogravimetric studies of the coals at three heating rates revealed distinct trends in behaviour with rank. The computerised data recording system also revealed more information about the pyrolysis of coals and allowed the tentative suggestion of a system of fingerprinting the pyrclytic behaviour of the coals. One avenue of further research could be the expansion and validation of this system. The kinetic analysis of the thermogravimetric results revealed that for each sample there are a series of temperature regions with their own activation energy. These regions and activation energies vary with the heating rate. It is suggested that each activation energy relates to a different kind of pyrolysis reaction, and although some suggestions have been made, further research incorporating other techniques is necessary to identify these reactions. The effect of the addition of some transition metal elements upon the activation energies for two of the samples was then investigated. It was found that most of the metals affected the activation energies in some way - either inhibiting or promoting the reactions. No general trends in behaviour were observed. Another possible avenue of further research is apparent here - to find out the ways in which these metals affect the production of the products of pyrolysis, particularly the gaseous products.

This dissertation presents contributions to the understanding of the dynamic nature of permeability of Indonesian coal. It is the first-of-its-kind study, first presenting a comparison of experimental results with those obtained using existing analytical permeability models, and then modifying the existing anisotropic model for application to the unique physical structure of Indonesian coal. The first problem addressed in this dissertation was establishing the pressure-dependentpermeability of coal in a laboratory environment replicating in situ conditions for two coal types from the Sanga Sanga basin of Kalimantan, Indonesia. The change in permeability with depletion and the corresponding volumetric strain of coal were measured in the laboratory under uniaxial strain condition (zero lateral strain). Two gases, helium and methane, were used as the flowing fluids during experimental work. The results showed that, decreasing pore pressure resulted in significant decrease in horizontal stress and increased permeability. The permeability increase at low reservoir pressure was significant, a positive finding for Indonesian coals. Using the measured volumetric changes with variations in pressure, the cleat compressibility for the two coal types was estimated. In a separate effort, volumetric strain as a result of desorption of gases was measured using sister samples under unconstrained condition, in absence of the stress effect. Sorptioninduced strain processes were modeled using the Langmuir-type model to acquire the two important shrinkage parameters. All parameters calculated using the experimental data were used for the modeling exercise. The second component of this dissertation is the permeability variation modeling to enable projecting long-term gas production in the Sanga Sanga basin. For this, two commonly used isotropic permeability models were selected. These models, developed primarily for the San Juan coal, were unable to match the measured permeability data. This was believed to be due to the inappropriate geometry used to represent Indonesian coal, where butt cleats are believed to be absent. This was followed by application of the most recent model, incorporating partial anisotropy in coal. This consideration improved the modeling results although there clearly was room for improvement. The final challenge addressed in this dissertation was to consider the coal geometry appropriate for Indonesian coal, stack of sheets as opposed to a bundle of matchsticks. In order to incorporate the structural anisotropy for the stack of sheets geometry, two input parameters were modified, based on geo-mechanical anisotropy. After applying these to the modified model, the permeability modeling results were compared with the experimental data. The matches improved significantly. Finally, the effect of maximum horizontal stress on permeability of coal was estimated by using high and low maximum horizontal stress values and constant vertical and minimum horizontal stresses. The effect of maximum horizontal stress on permeability was found to be significant under uniaxial strain condition for both coals.

Oxidative Hydrothermal Dissolution (OHD) is a coal conversion technique developed at SIUC that solubilizes coal by mild oxidation using molecular oxygen and hydrothermal water. Products are generally low-molecular-weight organic acids that could be used as chemical feedstocks. This project examined the influence of coal lithotype composition and pure maceral concentrates on the OHD process with a focus on reaction rate and products. Hand-picked lithotypes (vitrain, clarain, and fusain) from the Herrin, Springfield, and Murphysboro seams, as well as a cannel coal from the Brazil Block seam were subjected to OHD for 8, 16, 30, and 70 min. The 70-min run was a completion run whereas other times were pulse (incomplete reaction) runs. No significant differences were found in the OHD products even though previous work suggested maceral composition could affect final products. Most samples produced primarily mono- and di-acids due to the rank of the coal (high volatile bituminous). Pulse runs allowed for petrographic examination of the residue. OHD preferentially reacted with vitrinites and liptinites over the inertinites. Collodetrinite generally developed vacuoles before collotelinite whereas collotelinite developed reaction rims by 8-min. Liptinites developed reaction rims and loss of fluorescence. Semifusinites showed slight reaction rims at 8 min, though generally, inertinites did not display pronounced reaction rims until 30 min. Samples run under hydrolysis conditions revealed vacuoles and reaction rims could be produced with heat and pressure, but OHD conditions accelerate their production. Maceral concentrates produced different OHD products. Vitrinites and inertinites produced a similar suite of products with individual macerals missing a few products. Liptinite macerals (cutinite and sporinite) produced a different suite of products containing aliphatic acids as well as some products common to the vitrinites and inertinites. The cutinite suite was primarily aliphatic containing few aromatic compounds. The sporinite contained a mix of aliphatic and aromatic compounds. Vitrinites and inertinites produced a mix of mono-, di-, and tri-acids. Similarities in products between the vitrinites and inertinites are likely due to their origins from similar plant tissues (mostly woody material) that have undergone varying degrees of alteration by partial combustion, oxidation, etc. These similarities suggest that high inertinite coals could potentially produce similar OHD products to coals rich in vitrinite. The different products obtained from the macerals do suggest the potential for the OHD process to be tailored to produce specific compounds by varying the feedstock.