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1
Musser, Jordan M. H. "Development of a separation riser with flow pulsations for small coal particles." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4997.
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Thesis (M.S.)--West Virginia University, 2007.<br>Title from document title page. Document formatted into pages; contains xiii, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 70-72).
2
Yan, He Leo, and 嚴鶴. "Revitalization of abandoned coal washing site." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/196519.
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Pugalia, Neeraj. "Numerical modeling of cold flow and hot gas desulfurization in a circulating fluidized bed." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2056.
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Thesis (M.S.)--West Virginia University, 2001.<br>Title from document title page. Document formatted into pages; contains xvi, 119 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 103-106).
4
Davis, Van Leslie. "Characterization and scale-up of microbubble generation in column flotation." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03242009-040658/.
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Che, Zhuping. "Application and evaluation of spiral separators for fine coal cleaning." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10760.
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Thesis (M.S.)--West Virginia University, 2009.<br>Title from document title page. Document formatted into pages; contains viii, 72 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 46-48).
6
Brown, Michael Duane. "An investigation of fine coal grinding kinetics." Thesis, Virginia Tech, 1986. http://hdl.handle.net/10919/45752.
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In recent years, a great deal of interest has been shown in developing methods for preparing super—clean coal containing less than 2% ash and 0.5% sulfur. New techniques for recovering fine coal, such as micro—bubble flotation, can achieve the desired result provided mineral matter is sufficiently liberated. To achieve sufficient liberation, however, it is often necessary to grind to a mean particle size finer than 10 microns. Since conventional ball mills are highly inefficient in this fine size range, the stirred ball mill has been proposed as a more suitable means for ultrafine grinding.<br>Master of Science
7
pottimurthy, yaswanth. "Iron-Based Coal Direct Chemical Looping Process: Operation of Sub Pilot Scale Unit with Ohio #6 Bituminous Coal." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492129127522893.
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Oliver, Edmund T. "An investigation into the liberation characteristics of coal middlings." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.352934.
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Paul, Anton Dilojaan. "Electrocatalytically induced liberation of mineral matter from coal." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/82636.
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A new method for demineralizing coal has been developed which is based on the osmotic pressures that occur when electrical double layers overlap. In this technique, coal is exposed to ferric ions in an acidic medium which causes the coal to lose electrons and become positively charged, thereby establishing ionic double layers in the vicinity of its surface. Inside the pores and crevices in which mineral matter is entrapped, the ionic double layers overlap and reduce the chemical potential of water, creating an osmotic pressure. The build-up of such pressure pushes the mineral matter out of the crevices, resulting in mineral liberation. Since the process, which is termed electro catalytically induced liberation (EIL), relies on surface-chemical reactions, the energy consumption is substantially lower than in conventional liberation processes based on comminution.
Tests on several different seams of coal from varying geological locations have indicated that the process may be used to remove over 70% of the mineral matter present in coal. Mass balance studies conducted on a Wyodak coal indicate that approximately 90% of the ash removed is by the EIL mechanism, while the balance may be attributed to acid dissolution and the loss of material during handling. Scanning electron micrographs of the coal samples taken before and after treatment show morphological changes consistent with the proposed EIL mechanism. The technique has been used successfully to clean bituminous coals, low-rank coals and preparation plant refuse, and to further reduce the ash content of coals pre-cleaned by other means.
A theoretical model has been developed to calculate the osmotic pressure that occurs inside a typical coal crevice during the EIL treatment. The changes in the aqueous chemical potential are calculated using semi-empirical equations derived from solution theory, while partial molar volume changes are accounted for in the final calculation of the osmotic pressure. The model indicates that pressures on the order of 4-7 atmospheres can develop inside crevices with walls 100-1000Å apart. These values are numerically consistent with those predicted by other models developed using different approaches.<br>Ph. D.
10
Panday, Rupendranath. "Modeling, identification and control of a cold flow circulating fluidized bed." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5833.
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Thesis (M.S.)--West Virginia University, 2008.<br>Title from document title page. Document formatted into pages; contains xiii, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 94-99).
11
Keyser, Paul Martin. "Continuous column flotation of ultrafine coal using microbubbles." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/90973.
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A flotation column has been developed Incorporating the use of fine air bubbles (less than 100 microns) to remove ash-forming minerals from micronized coal. The microbubble generator used In this work has been characterized and found to yield a very narrow size distribution. Microbubble column flotation tests have been conducted to study a series of operating variables such as time, bubble size, feed rate, feed point, feed percent solids, column height, bubble number concentration, make-up water addition and countercurrent wash water addition. The results show that i) fine air bubbles are Inherently better suited for floating small particles; ii) both ash and recovery rates Increase with Increasing feed rate, distance of the feed point from the tailings port, feed percent solids and bubble number concentration; iii) taller columns result In Improved recovery and ash rejection; and iv) the countercurrent wash water addition minimizes the entrainment of mineral matter to the froth product. Proper control of these parameters makes It possible to produce super clean coal (< 2% ash).<br>M.S.
12
Akhtar, Haroon. "Development of a small separation riser for fine coal particles." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4466.
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Thesis (M.S.)--West Virginia University, 2006.<br>Title from document title page. Document formatted into pages; contains ix, 81 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 68-69).
13
Hale, Waverly Mitchell. "Surface chemical aspects of microbubble flotation." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45816.
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<p>In order to demonstrate the ability of microbubble
flotation to superclean coal to ash levels of less than
2%, several Eastern U. S. coals have been tested. The
results show that the process is capable of producing
superclean coal with improved recovery as compared to the
conventional flotation process.<p>
<p>
To further improve and understand the microbubble
flotation process, electrokinetic studies of the
hydrocarbon oils used in flotation as collectors have been
conducted. Also, the effect of oil emulsifiers on the zeta
potential of oil droplets has been studied. In general,
oil droplets are negatively charged and negative zeta
potential is reduced with the addition of nonionic and
cationic surfactants. On the other hand, the negative
charge is increased with the addition of an anionic
reagent. It has also been shown that the negative zeta
potential of oil droplets increases with increasing
hydrocarbon chain length.<p>
<p>The effects of different collectors on induction time
and flotation have been determined by conducting
microflotation and induction time experiments using an
Elkhorn seam coal sample. The results show that industrial
oils combined with the coal have the shortest induction
times and, therefore, the highest flotation yields as
compared to pure hydrocarbon oils. It has also been shown
that oil emulsifiers tend to increase flotation yield and
reduce particle/bubble induction time.<p><br>Master of Science
14
Dieudonne, Vincent. "Chemical and Electrochemical Coal Cleaning in acidic medium application and analysis of the process." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43846.
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Halsey, Gregory S. "A preliminary investigation of microbubble flotation of fine coal." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/94456.
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Although froth flotation is generally recognized as the most viable means of cleaning fine coal, a loss in recovery rate and selectivity is encountered when attempting to apply the process to clean ultrafine coals. In this work, batch flotation tests were conducted on several Appalachian coals using microbubbles in a cylindro-conical flotation column. Results indicate that this technique shows improvements over the conventional technique using larger bubbles, when the coal is ultrafine. The improvement in recovery rate with the microbubbles is due to improved hydrodynamic conditions which are more conducive to bubble/particle collision, while the improvement in selectivity is due to the absence of turbulent wakes.<br>M.S.
16
Vargas, Duarte Gerardo. "An experimental study of the hydrodynamics of multiphase flow in fluidized beds." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Schroedter, Taylor L. "Conceptual Design of a Pilot-Scale Pressurized Coal-Feed System." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7717.
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This thesis discusses the results and insights gained from developing a CFD model of a pilot-scale pressurized dry coal-feed system using the Barracuda CFD software and modeling various design concepts and operating conditions. The feed system was required to transport approximately 0.00378 kg/s (30 lb/hr) of pulverized coal from a vertical hopper to a 2.07 MPa (20.4 atm or 300 psi) reactor with a CO2-to-coal mass flow ratio of 1-2. Two feed system concepts were developed and tested for coal mass flow, CO2-to-coal mass ratio, steadiness, and uniformity. Piping system components also were evaluated for pressure drop and coal roping.With the first system concept, Barracuda software model parameters were explored to observe their effect on gas and particle flow. A mesh sensitivity study revealed there exists too fine of a mesh for dual-phase flow with Barracuda due to the particle initialization process. A relatively coarse mesh was found to be acceptable since the results did not change with increasing mesh refinement. Barracuda sub-model parameters that control particle interaction were investigated. Other than the close pack volume fraction, coal flow results were insensitive to changes in these parameters. Default Barracuda parameters were used for design simulations.The gravity-fed system (first concept) relied on gravity to transfer coal from a hopper into the CO2 carrier gas. This design was unable to deliver the required coal mass flow rate due to the cohesion and packing of the particles being greater than the gravity forces acting on the particles. The fluidized bed (second concept) relied on CO2 flow injected at the bottom of the hopper to fluidize the particles and transport them through a horizontal exit pipe. Additional CO2 was added post-hopper to dilute the flow and increase the velocity to minimize particle layout. This concept was shown to decouple the fluidized particle flow and dilution CO2 flow, providing significant design and operating flexibility. A non-uniform mesh was implemented to maintain a high mesh refinement in the 0.635-cm (¼-in) diameter transport pipe with less refinement in the hopper/bed region. The two main hopper diameters evaluated measured 5.08-cm (2-in) and 15.24-cm (6-in). Successful designs were achieved for each with appropriate coal mass flow rates and CO2-to-coal ratios. The particle flow was sufficiently steady for use with a coal burner.A piping system study was performed to test pneumatic transport and the effects of pipe length and bend radius. For a 1-to-1 gas-to-particle mass flow, particle layout occurred after 30 cm of travel. Particle roping occurred to various extents depending on the pipe bend radius. Bend radii of 0.318, 60.96, and 182.88 centimeters were simulated. Roping increased with bend radius and high pressure. Greater gas flow rates increased particle flow steadiness and uniformity. A simple methodology was identified to estimate the pressure drop for different piping system configurations based on the piping components simulated.
18
McKeon, Timothy Josiah. "An In-Plant Evaluation of Froth Washing on Conventional Flotation Cells for Coal." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35708.
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Column flotation cells have become increasingly popular in the coal industry due to their ability to improve flotation selectivity. The improvement can be largely attributed to the use of froth washing, which minimizes the nonselective entrainment of ultrafine minerals matter into the froth product. Unfortunately, the practice of adding wash water in conventional flotation machines has been largely unsuccessful in industrial trials. In order to better understand the causes of these failures, a detailed in-plant test program was undertaken to evaluate the use of froth washing at an operating coal preparation plant. The tests included detailed circuit audits (solid and liquid mass balances), salt tracer studies, and release analyses. The data collected from these tests have been used to develop criteria that describe when and how froth washing may be successfully applied in industrial flotation circuits.
A second series of tests was developed to look at other alternatives to froth washing and their effectiveness. This involved two-staged flotation circuitry. A two-staged approach was developed because the existing flotation cells did not have enough residence time to support froth washing. The process owner wanted to evaluate possible alternatives to column cell flotation. The testing included release analysis testing as well as a detailed series of tests with percent solids control to the secondary flotation unit.<br>Master of Science
19
Gray, Stuart. "Groundwater remediation using a coal washery discard permeable reactive wall." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20061017.133840/index.html.
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Estejab, Bahareh. "Hydrodynamic and gasification behavior of coal and biomass fluidized beds and their mixtures." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/79366.
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In this study, efforts ensued to increase our knowledge of fluidization and gasification behavior of Geldart A particles using CFD. An extensive Eulerian-Eulerian numerical study was executed and simulations were compared and validated with experiments conducted at Utah State University. In order to improve numerical predictions using an Eulerian-Eulerian model, drag models were assessed to determine if they were suitable for fine particles classified as Geldart A. The results proved that if static regions of mass in fluidized beds are neglected, most drag models work well with Geldart A particles. The most reliable drag model for both single and binary mixtures was proved to be the Gidaspow-blend model. In order to capture the overshoot of pressure in homogeneous fluidization regions, a new modeling technique was proposed that modified the definition of the critical velocity in the Ergun correlation. The new modeling technique showed promising results for predicting fluidization behavior of fine particles. The fluidization behavior of three different mixtures of coal and poplar wood were studied. Although results indicated good mixing characteristics for all mixtures, there was a tendency for better mixing with higher percentages of poplar wood.
In this study, efforts continued to model co-gasification of coal and biomass. Comparing the coal gasification of large (Geldart B) and fine (Geldart A) particles showed that using finer particles had a pronounced effect on gas yields where CO mass fraction increased, although H2 and CH4 mass fraction slightly decreased. The gas yields of coal gasification with fine particles were also compared using three different gasification agents. Modeling the co-gasification of coal-switchgrass of both fine particles of Geldart A and larger particles of Geldart B showed that there is not a synergetic effect in terms of gas yields of H2 and CH4. The gas yields of CO, however, showed a significant increase during co-gasification. The effects of gasification temperature on gas yields were also investigated.<br>Ph. D.
21
Wimer, Bryan M. "Fine particle separation in a riser with flow modifications." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5047.
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Thesis (M.S.)--West Virginia University, 2007.<br>Title from document title page. Document formatted into pages; contains xi, 133 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 119-120).
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Tuia, Jacob Talailetalalelei. "Correlating Pressure, Fluidization Gas Velocities, andSolids Mass Flowrates in a High-PressureFluidized Bed Coal Feed System." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7546.
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The goal of this thesis was to understand what parameters would be most impactful when delivering dry, pulverized coal in a dilute-phase, with a high-pressure feed-system to a pressurized oxy-combustion (POC) reactor. Many studies have conveyed materials in dense-phase plugs at high-pressure or in dilute-phase flows at atmospheric pressure. Very few studies have fluidized and conveyed materials in dilute-phase flows at high pressure, as we needed to. Additionally, studies which might have been applicable based upon system -pressure and -phase delivered findings that were empirically based and therefore not specifically applicable to non-similar systems. 220 different tests were ran using a bench-scale apparatus consisting of a hopper, connecting conveying pipes, and a filter point (representing the future reactor). The system was pressurized to 300 psi using CO2. Dry, pulverized coal with an average diameter of 50 microns and a bulk density of 800.9 kg/m3 was fluidized and conveyed with different combinations of fluidization inlet and fluidization outlet flowrates. Each specific flowrate combination was tested 3 to 5 times. The resulting coal flowrates were recorded and analyzed to see which flowrate combination delivered 13.6 kgs coal/hr and had the least variability between tests. The fluidization inlet and outlet flowrates, coal moisture content, and system geometry were key parameters. In a 2-inch diameter hopper the fluidization inlet flowrate should be kept at 0.119 m/s or below to keep the fluidization regime within the hopper below the transition point to the bubbling fluidization regime. This was beneficial since less CO2 was needed by the system and smaller perturbations within the bed didn't disrupt flow leaving the hopper. The fluidization outlet flowrate could still advance the fluidization regime within the hopper even if the fluidization inlet flowrate is kept at 0.119 m/s. For a ¼ inch diameter the outlet should be kept at 0.005 m/s or above. Additionally, the standard deviation in the measured coal flowrate decreased dramatically when flow of gas was allowed to exit through the top of the coal column (fluidization outlet). The standard deviation was 8.2 kg/hr with the fluidization outlet closed and 3.5 kg/hr with the fluidization outlet flowing to provide 0.005 m/s in the bed above the coal outlet. Coal should have a moisture content between 3% and 6% to ensure that electrostatic interactions between coal particles is kept to a minimum. Finally, these results were found for specific hopper and fluidization inlet and outlet diameters. If these diameters are changed then some calculation must be done for these results to be applicable to systems that are not like the one described later in this thesis.
23
Jain, Riddhika. "Processing of Low Rank Coal and Ultrafine Particle Processing by Hydrophobic-Hydrophilic Separation (HHS)." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51565.
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This thesis pertains to the processing of ultra-fine mineral particles and low rank coal using the hydrophobic--hydrophilic separation (HHS) method. Several explorative experimental tests have been carried out to study the effect of the various physical and chemical parameters on the HHS process.
In this study, the HHS process has been employed to upgrade a chalcopyrite ore. A systematic experimental study on the effects of various physical and chemical parameters such as particle size, reagent dosage and reaction time on the separation efficiencies have been performed. For this, a copper rougher concentrate (assaying 15.9 %Cu) was wet ground and treated with a reagent to selectively hydrophobize the copper-bearing mineral (chalcopyrite), leaving the siliceous gangue minerals hydrophilic. The slurry was subjected to a high-shear agitation to selectively agglomerate the chalcopyrite and to leave the siliceous gangue dispersed in aqueous phase. The agglomerates were then separated from dispersed gangue minerals by screening and the agglomerates dispersed in a hydrophobic liquid (n-pentane) to liberate the water trapped in the agglomerates. The chalcopyrite dispersed in the hydrophobic liquid was separated from the medium to obtain a concentrate substantially free of gangue minerals and moisture. The copper recoveries were substantially higher than those obtained by flotation. The HHS process was also tested on ultrafine mono-sized silica beads. The results were superior to those obtained by flotation, particularly with ultrafine particles.
The HHS process has also been tested successfully for upgrading subbituminous coals. Low-rank coals are not as hydrophobic as high-rank coals such as bituminous and anthracite coals. In the present work, a low-rank coal from Wyoming was hydrophobized with appropriate reagents and subjected to the HHS in a similar manner as described for processing copper. The results showed that the HHS process reduced the moisture substantially and increased the heating value up to 50% without heating the coal. Laboratory-scale tests conducted under different conditions, e.g., particle size, reagent type, reaction time, and pretreatments, showed promising results. Implementation for the HHS process for upgrading low-rank coals should help reduce CO2 emissions by improving combustion efficiencies.<br>Master of Science
24
Agarwal, Gaurav. "Solid Fuel Blend Pyrolysis-Combustion Behavior and Fluidized Bed Hydrodynamics." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51677.
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As a carbon neutral and renewable source of energy, biomass carries a high potential to help sustain the future energy demand. The co-firing of coal and biomass mixtures is an alternative fuel route for the existing coal based reactors. The main challenges associated with co-firing involves proper understanding of the co-firing behavior of blended coal-biomass fuels, and proper understanding of advanced gasification systems used for converting such blended fuels to energy.
The pyrolysis and combustion behavior of coal-biomass mixtures was quantified by devising laboratory experiments and mathematical models. The pyrolysis-combustion behavior of blended fuels was quantified on the basis of their physicochemical, kinetic, energetic and evolved gas behavior during pyrolysis/combustion. The energetic behavior of fuels was quantified by applying mathematical models onto the experimental data to obtain heat of pyrolysis and heat of combustion. Fuel performance models were developed to compare the pyrolysis and combustion performance of non-blended and blended fuels. The effect of blended fuel briquetting was also analyzed to find solutions related to coal and biomass co-firing by developing a bench scale fuel combustion setup. The collected data was analyzed to identify the effects of fuel blending and briquetting on fuel combustion performance, ignitability, flammability and evolved pollutant gases.
A further effort was made in this research to develop the understanding of fluidized bed hydrodynamics. A lab scale cold-flow fluidized bed setup was developed and novel non-intrusive techniques were applied to quantify the hydrodynamics behavior. Particle Image Velocimetry and Digital Image Analysis algorithms were used to investigate the evolution of multiple inlet gas jets located at its distributor base. Results were used to develop a comprehensive grid-zone phenomenological model and determine hydrodynamics parameters such as jet particle entrainment velocities and void fraction among others. The results were further used to study the effect of fluidization velocity, particle diameter, particle density, distributor orifice diameter and orifice pitch on the solid circulation in fluidized beds.<br>Ph. D.
25
Bayham, Samuel C. "Iron-Based Coal Direct Chemical Looping Process for Power Generation: Experimental Aspects, Process Development, and Considerations for Commercial Scale." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1425759077.
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Moraes, Anderson Antonio Ubices de. "Modelagem e simulação da combustão em leito fluidizado de carvão mineral com alto teor de cinzas com dessulfuração por calcário." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-20062011-204522/.
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A geração de energia em larga escala a partir da combustão de carvões minerais impõe pesados ônus ao meio ambiente devido às emissões de poluentes. O processo de combustão em leito fluidizado destaca-se neste contexto, permitindo reduções de emissões de gases \'SO IND.X\' e \'NO IND.X\' acima de de 90%. O projeto, otimização e escalonamento de reatores de leito fluidizado são realizados de forma quase completamente empírica, através de desenvolvimentos em plantas de demonstração de escalas reduzidas. Os custos e tempos de implementação envolvidos são elevadíssimos, tornando ferramentas teóricas de apoio altamente desejáveis. Neste trabalho, desenvolve-se a modelagem e simulação da combustão em leito fluidizado atmosférico borbulhante de carvão mineral com altos teores de cinzas e enxofre com dessulfuração por calcário, através de uma abordagem fenomenológica. Comparações das predições do modelo são realizadas com dados experimentais gerados na planta piloto do NETeF, e estudos paramétricos são realizados para avaliação das performances do reator. As comparações mostram concordâncias e discrepâncias qualitativas e quantitativas entre perfis simulados e medidos das concentrações de gases e distribuições granulométricas do particulado. Isso indica a necessidade de aperfeiçoamentos na modelagem fenomenológica, notadamente com relação às correlações e dados empíricos utilizados. Apesar das discrepâncias, o modelo apresenta bons resultados quantitativos de eficiência de absorção de enxofre em comparação com os dados experimentais.<br>Energy generation through coal combustion imposes heavy environmental impacts due to pollutant emissions. The process of fluidized bed combustion distinguishes in this context allowing for emission reductions of \'SO IND.X\' and \'NO IND.X\' above 90%. The design, scaling-up, and optimization of fluidized bed reactors are mostly empirical, through small-scale demonstration plant developments. The costs and times of implementation involved in those developments are huge, making theoretical tools of analysis highly desirable. In this work modeling and simulation are performed for atmospheric bubbling fluidized bed combustion of high ash high sulfur coals, including desulfurization by limestone. A phenomenological approach to modeling is applied. Comparison of predictions are made against empirical measurements performed in the NETF pilot plant, and parametric studies are developed to evaluate reactor performances. The comparisons show both agreements and disagreements, qualitative as well as quantitative, between predictions and measured gas concentrations and particulate size distributions. This points to the necessity for improvements on the phenomenological modeling procedure that was applied, notably regarding the empirical correlations and data that were considered. Despite the discrepancies, the model produces good quantitative results of sulfur absorption efficiency in comparison to the empirical data.
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Linhares, Felipe de Aguiar de. "Avaliação fluidodinâmica e processo de co-combustão de resíduo de casca de acácia negra com carvão mineral em planta piloto de leito fluidizado borbulhante." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/156803.
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A preservação ambiental e o uso de combustíveis fósseis para geração de energia têm estimulado a realização de pesquisas na busca de alternativas para a redução das emissões de gases poluentes como CO2, CO, SO2 e NOx. O uso da biomassa em sistemas de co-combustão em leito fluidizado é mencionado como uma destas alternativas. O presente trabalho utilizou biomassa residual da indústria de extração de tanino, o Resíduo de Cascas de Acácia Negra (RCAN), em conjunto com carvão mineral da Mina de Candiota – RS com o objetivo de estudar a fluidodinâmica entre diferentes composições destes materiais em sistema de leito fluidizado com areia em escala de laboratório e em uma unidade piloto. Também foi realizada a avaliação dos parâmetros operacionais e das emissões dos gases gerados na co-combustão das misturas em planta piloto com reator de leito fluidizado borbulhante. Durante a fluidização no sistema de escala laboratorial, os valores da velocidade mínima de fluidização, Umf, variaram consideravelmente com o aumento da concentração de RCAN no leito em relação à fluidização utilizando-se somente o carvão mineral Da mesma forma, a queda de pressão, ΔP, diminuiu com o aumento da concentração da biomassa no leito. Nas operações de co-combustão em planta piloto, as misturas de carvão mineral e RCAN necessitaram de menores porcentagens de excesso de ar (99,7% a 65,2%) no reator em comparação à queima apenas de carvão mineral (108,4% a 107,5%) para que se atingisse a temperatura de operação do leito. Em particular, a condição de maior quantidade de biomassa na alimentação pode se observar a menor porcentagem de excesso de ar (50,8%). Ainda, a co-combustão do RCAN com carvão mineral favoreceu a diminuição das concentrações de SO2 nos gases gerados em mais de 90%, mantendo as emissões em níveis aceitáveis conforme os limites de emissão estabelecidos pela resolução CONAMA Nº 436, de 22/12/2011 e Resolução SEMA Nº 016 de 2014.<br>The environmental issues brought by the use of fossil fuels for power generation have led to the development of research in the exploration for alternatives to reduce emissions of greenhouse gases or pollutants such as CO2, CO, SO2, and NOx. The biomass use in cofiring systems with fluidized bed has been mentioned as one of these alternatives. The present work used biomass waste from tannin extraction industry, Black Wattle Bark Waste (BWBW), jointly with coal for the purpose of studying the fluid dynamics biomass mixtures with coal and sand in different proportions of the materials in laboratory scale fluidized bed system. Also, operational parameters and emissions generated in a cofiring pilot plant with bubbling fluidized bed reactor were evaluated. The fluidization tests performed on a bench scale showed that the values of the minimum fluidization velocity, Umf, varied considerably with increasing concentration of BWBW compared with the fluidization of coal. Likewise, the pressure drop through the bed, ΔP, decreased with increasing concentration of biomass in the bed. In the cofiring operations, coal and mixtures BWBW required smaller percentages of excess air in the reactor (99,7% a 65,2%) in comparison with the pure coal (108,4% a 107,5%) burning to obtaining the bed operating temperature. The burning of the mixture with higher amounts of biomass in the reactor feed had the lowest percentage of excess air (50.8%). It was also evidenced a decrease of SO2 generation in more than 90% for the flue gas generated in the coal with BWBW cofiring keeping emissions at acceptable levels in comparison with emission limits of current legislation CONAMA Nº 436, from 22/12/2011 and legislation SEMA Nº 016 of 2014.
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Marie, Béatrice. "Etudes hydrodynamiques sur la combustion du charbon dans le foyer d'une chaudiere ignifluid." Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0062.
Full textAbstract:
L'etude du procede ignifluid de combustion du charbon en lit fluidise a ete realisee sur une chaudiere industrielle et sur deux maquettes modeles reduits du foyer. A partir d'essais sur maquette rectangulaire, on a propose un schema d'ecoulement des gaz et des solides dans le lit
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"An investigation of the hydrodynamics of the teetered bed separator for fine coal recovery." Thesis, 2005. http://hdl.handle.net/10413/2726.
Full textAbstract:
The South African coal industry produces a
large quantity of coal per annum. The rejects
from various unit operations, such as spirals,
consist of fine coal that joins the plants
tailings dam waste. As existing high quality
resources become depleted, the need to improve
recovery of this fine coal grows. This project
investigates the use of a teetered bed
separator (TBS); a hindered settling gravity
concentration device for fine coal recovery.
This device has proven successful in the
United Kingdom and in Australian collieries
for fine coal separation in the size range
between 2mm and 0.3mm. It has also been used
for decades as a classifying device for silica
sand and tin. The TBS operates in the size
range of water-only cyclones and spiral
concentrators, and could potentially be used
to separate a broader size range of coal fines
so as to offer a lower footprint device for
the fines recovery section of a plant. Spiral
concentrators cannot always be operated
efficiently at a separating specific gravity
of lower than 1.6; a TBS may also extend the
density range for separation and thus improve
recovery. The objective of this project was to
gain a full understanding of the TBS from
fundamental particle interaction and develop a
lab scale unit, which is capable of separation
to about 0.1mm at optimum conditions. This
involved the development of design parameters
based on the various distributor plates and
flow pattern modelling. The hydrodynamics of
the separator were investigated using the
Eulerian-Eulerian modelling approach of
commercial CFD package, Fluent 6.1. Seven
distributor plates of varying aperture size
and geometric arrangement were considered.
Coal and shale particles, sized between 2mm
and 0.038mm with a specific gravity (SG) range
of 1.2 to 2.0, were separated using the
laboratory scale unit. The results of both the
simulations and the laboratory tests were then
compared. The simulations revealed that Plate
3 was the best option for implementation. It
had an even upward velocity profile compared
to the other plates, with minimum wall effects
and disturbances. The upward water flow rate
(teeter water) was varied experimentally and
the composition of the teeter bed, underflow
and overflow were analysed using 1.5, 2 and
Smm cubic density tracers with an SG range of
1.2-2.0. Analysis of the partition curves of
the distributor plates revealed that Plate 3
had the lowest Ecart Probable (Ep) and cut-
point densities. The comparison of simulated
results and experimental results show that the
simulator could predict the distributor plate
design with the lowest Ep in practical tests.
The simulator could be beneficial when
optimising an industrial scale unit, by
allowing prediction of improved segregation
patterns and thus separation efficiency.<br>Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.
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Chen, Wen-Ben, and 陳文彬. "Investigation the Effect of Washing Reagent on the Physico-chemical Properties of Coal Fly Ash." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/54310776631865085685.
Full textAbstract:
碩士<br>國立屏東科技大學<br>環境工程與科學系所<br>96<br>Coal fly ash is generated from the air-pollution control devices of coal-burn electric-generation plants. Because the producing amount is huge day by day, and non-hazardous, coal fly ash has already changed into a additive industrial waste into a mineral additive of concrete, to improve the defect of the traditional concrete. The nature of the coal fly ash is influenced by the coal source, system of burning, operating conditions and environmental factor etc, resulted in a unstable quality and various appearent color of coal fly ash. This research focused on the effect of different washing reagent on physico-chemical property of washed ash. In this study, for the ashes were collected from the coal-fired and oil-fired plants. Results indicate that the washing treatment actually improves the compression strength of acetone-washed ash concrete by 15 kg/cm2, and reduces the oil content. In addition the residual percentage of <#500 mesh sieve has increased to be 15~20%. The economic analysis also illustrated that acetone is a better washing reagent that water for coal fly ash.
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Mukatuni, Sedzani. "Geology and characterization of coal at the Mushithe Coal Occurrence, Soutpansberg Coalfield, Limpopo Province, South Africa." Diss., 2019. http://hdl.handle.net/11602/1456.
Full textAbstract:
MESMEG<br>Department of Mining and Environmental Geology<br>The Mushithe coal occurrence is situated approximately 16 km west of the Tshikondeni coal mine in the Tshipise-Pafuri sub-basin of the Soutpansberg coalfield in South Africa. The Soutpansberg Coalfield has received comparatively less attention compared to other more notable South African coalfields. There is as a consequence very limited information in the public domain applicable to the geology as well as quality of coal in this coalfield, as a result there is no known study focused exclusively on the Mushithe coal occurrence.
The aim of the study was to conduct detailed geological mapping of the Mushithe Deposit so as to ascertain the geological environment and petrological characteristics of rocks within the area. Further work involved coal sampling and analysis in order to establish coal quality and its physical and chemical characteristics.
Samples were collected using geological field mapping and channel sampling. Nine coal samples were collected from the coalbed and host rock, exposed along the Mbodi River, during geological field mapping using channel sampling. Furthermore, 92 rock samples were collected during geological field mapping of which 10 representative samples were selected for further analysis. X-ray fluorescence spectrometry was conducted on all selected samples. Proximate analysis and ultimate analyses, and calorimetry tests were undertaken on coal samples. Three samples were selected based on calorific value for maceral identification, mineral analyses and vitrinite reflectance using petrographic study.
Detailed geological mapping of the area around the Mushithe coal occurrence showed the geological setting of coal in this area. The following lithologies were identified in the study area: sandstone, mudstone, ironstone, calcrete, shale, quartzite, quartz vein with a general strike direction to the north-east. The host rocks including coal were intruded by dolerite dykes and this resulted in the devolatilization of coal.
The current study concluded that the Mushithe coal was formed in a wet swampy environment. This has been confirmed based on tissue preservation index (1.69) and
gelification index (2.35). Coal rank ranged from bituminous Rank C- B according to United Nations Economic Commission for Europe Coal Classification (UNECE) and samples were characterised by high ash (27.90%), high moisture (10.47%) and low sulphur (0.24%). Furthermore, coal was graded below grade D based on classification for use by ESKOM which consider any calorific value below 24.5 MJ/kg to be in this category. The coal is vitrinite rich (77.75 vol%) and low in Inertinite (22.25 vol%) and devoid of Liptinite and pseudovitrinite, thus it is of good coking quality. Geochemical analysis revealed that the coal was enriched in TiO2 and Fe2O3 which was corroborated by the mineral matter which was mostly clay and pyrite. Comparatively, coal quality analysis revealed the calorific value of 14.26 MJ/kg and vitrinite reflectance between 0.94 %ROV to 1 %ROV which was less than that of the Tshikondeni Deposit but greater than that at Waterberg coalfield.
The study recommends further detailed exploration of coal in the area, applying such techniques such as geophysical exploration and borehole drilling leading to resource evaluation. Further studies are recommended to provide a better interpretation of the depositional environment of coal at Mushithe as well as the effect of devolatilaziton by a dolerite dyke.<br>NRF
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Du, Plessis Cheryl. "Investigating the opportunity to increase yield by means of froth washing on mechanical coal flotation cells." Thesis, 2018. https://hdl.handle.net/10539/26587.
Full textAbstract:
MSc (50/50)
School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa
July, 2018<br>Froth washing is a process where water is injected or sprayed onto or into the froth to remove or flash-down gangue particles present in the froth because of hydraulic entrainment. This process was recently tested at Anglo American’s Goedehoop South (GHS) Flotation plant to evaluate its effects on the yield and product quality during coal fines flotation. The research aimed to design a suitable and effective froth wash system, and to use this design to test froth washing. The most suitable froth wash design was found to be a lip wash design. The performance of flotation cells with lip washing were compared to flotation without lip washing. The primary goal of the study was to determine whether lip washing on flotation cells can improve yield while maintaining the required product quality. The flotation plant produces an A grade thermal coal product with a target product calorific value (CV) of 27.30 MJ/kg (air dry basis), known within Anglo thermal coal as an AAC product.
The test work compared different scenarios of lip wash against the current plant performance. This was done by sampling two identical flotation lines feeding from the same head box. One flotation line was run at the current optimum plant operating parameters to represent the current plant performance. On the other line a lip wash design was installed and different scenarios were applied to the lip wash line. The flotation reagent dosage on the flotation cells line without lip washing was kept constant at 1.3 kg/t which corresponds to the optimized plant operating dosage. The flotation reagent dosage on the flotation line with lip washing was varied between 1.3 kg/t and 1.75 kg/t to determine the optimum dosage rate that could be used when applying lip wash. Various configurations of froth washing was also tested, washing was either done on the primary flotation cell, i.e. primary wash only (PWO) or on the secondary flotation cell which is fed from the underflow of the primary cell, i.e. secondary wash only (SWO) or on both primary and secondary cells. Some experimental runs were done at specific settings to evaluate the effects of lip wash when different feed types are used. All the lip washing tests were compared with a baseline test where no lip washing was done (and therefore to current plant performance).
The results of the test work showed that lip washing can increase product yields on the flotation cells by 8% - 40%, depending on the type and quality of the feed fed to the cells. Lip wash can increase yields without compromising product quality for reagent dosages of 1.3kg/ton-1.45kg/ton. An interesting observation was that lip wash increased yields while achieving similar product qualities at the current plant’s optimum reagent dosage of 1.3kg/ton, contrary to froth wash studies in literature where froth wash leads to a decrease in yield and increase in product quality. Primary wash only (PWO) was found to achieve higher product yield than secondary wash only (SWO), however the resultant product quality was found to be poorer than that achievable by SWO and baseline flotation cells. SWO produced higher yields than baseline cells while achieving a better product quality as well.
The advantages of applying lip wash were found to be significantly higher when washing poorer feed material that results in low yields in the conventional flotation plant without lip wash (yields between 10%-40%). Yield increases between 30-40% were observed when lip wash is introduced to flotation cells floating low yielding coals.
The mechanisms that are potentially responsible for the increased yield and high product qualities when lip washing is applied are a combination of the following:
i. The increased froth mobility due to lip wash
ii. Lip wash water washing hydraulically entrained material out of the froth phase and back to the pulp phase
iii. The reduced residence time on the secondary cleaning stage resulting in a reduction in coalescence of bubbles in the froth phase.<br>E.R. 2019
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Roets, Leon. "The effect of mineral addition on the pyrolysis products derived from typical Highveld coal / Leon Roets." Thesis, 2014. http://hdl.handle.net/10394/15528.
Full textAbstract:
Mineral matter affect various coal properties as well as the yield and composition of products released during thermal processes. This necessitates investigation of the effect of the inherent minerals on the products derived during pyrolysis, as pyrolysis forms the basis of most coal utilisation processes. A real challenge in this research has been quantifying the changes seen and attributing these effects to specific minerals. Thus far it has been deemed impossible to predict product yields based on the mineral composition of the parent coal. Limited research regarding these aspects has been done on South African coal and the characterisation of pyrolysis products in previous studies was usually limited to one product phase. A novel approach was followed in this study and the challenges stated were effectively addressed.
A vitrinite-rich South African coal from the Highveld coal field, was prepared to an undersize of 75 μm and divided into two fractions. HCl/HF acid washing reduced the ash yield from 14.0 wt% d.b. to 2.0 wt% d.b. (proximate analysis). Pyrolysis was carried out with the North-West University (NWU) Fischer Assay setup at 520, 750 and 900°C under N2 atmosphere and atmospheric pressure. The effect of acid washing and the addition of minerals on the derived pyrolysis products were evaluated.
Acid washing led to lower water and tar yields, whilst the gas yields increased, and the char yields were unaffected. The higher gas yield can be related to increased porosity after mineral removal as revealed by Brunauer-Emmett-Teller (BET) CO2 adsorption surface area analysis of the derived chars. Gas chromatography (GC) analyses of the derived pyrolysis gases indicated that the acid washed coal fraction (AW TWD) derived gas contained higher yields of H2, CH4, CO2, C2H4, C2H6, C3H4, C3H6 and C4s when compared to the gas derived from the raw coal fraction (TWD). The CO yield from the TWD coal was higher at all final pyrolysis temperatures. Differences in gas yields were related to increased tar cracking as well as lower hydrogen transfer and de-hydrogenation of the acid washed chars. Analyses of the tar fraction by means of simulated distillation (Simdis), gas chromatography mass spectrometry (GC-MS) –flame ionization detection (–FID) and size exclusion chromatography with ultraviolet (SEC-UV) analyses, indicated that the AW TWD derived tars were more aromatic in nature, containing more heavier boiling point components, which increased with increasing final pyrolysis temperature. The chars were characterised by proximate, ultimate, X-ray diffraction (XRD), X-ray fluorescence (XRF), diffuse reflectance infrared Fourier-transform (DRIFT) and BET CO2 analyses.
Addition of either 5 wt% calcite, dolomite, kaolinite, pyrite or quartz to the acid washed fraction (AW TWD) was done in order to determine the effect of these minerals on the pyrolysis products. These minerals were identified as the most prominent mineral phases in the Highveld coal used in this study, by XRD and quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) analyses. It was found that mineral activity decreased in the order calcite/dolomite>pyrite>kaolinite>>>quartz. Calcite and dolomite addition led to a decrease in tar yield, whilst the gas yields were increased. Markedly, increased water yields were also observed with the addition of calcite, dolomite and pyrite. Kaolinite addition led to increased tar, char and gas yields at 520°C, whilst the tar yield decreased at 750°C. Pyrite addition led to decreased tar and gas yields. Quartz addition had no noteworthy effect on pyrolysis yields and composition, except for a decrease in char yield at all final pyrolysis temperatures and an increased gas yield at 520°C. Regarding the composition of the pyrolysis products, the various minerals had adverse effects. Calcite and dolomite affected the composition of the gas, tar and char phases most significantly, showing definite catalytic activity. Tar producers should take note as presence of these minerals in the coal feedstock could have a significant effect on the tar yield and composition. Kaolinite and pyrite showed some catalytic activity under specific conditions. Model coal-mineral mixtures confirmed synergism between coal-mineral and mineral-mineral interactions. Although some correlation between the pyrolysis products derived from the model coal-mineral mixtures and that of TWD coal was observed, it was not possible to entirely mimic the behaviour of the coal prior to acid washing.
Linear regression models were developed to predict the gas, tar and char yields (d.m.m.f.) with mineral composition and pyrolysis temperature as variables, resulting in R2 coefficients of 0.837, 0.785 and 0.846, respectively. Models for the prediction of H2, CO, CO2 and CH4 yields with mineral composition and pyrolysis temperature as variables resulting in R2 coefficients of 0.917, 0.702, 0.869 and 0.978, respectively. These models will serve as foundation for future work, and prove that it is feasible to develop models to predict pyrolysis yields based on mineral composition. Extending the study to coals of different rank can make the models universally applicable and deliver a valuable contribution in industry.<br>MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2015