Dissertations / Theses on the topic 'Catalytic cracking'
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Albahri, Tareq Abduljalil. "Mechanistic modeling of catalytic cracking chemistry /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Nazarudin, N. "Catalytic cracking of plastic waste using nanoporous materials." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1380400/.
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The catalytic cracking of linear low density polyethylene (lldPE), polypropylene (PP) and plastic waste were investigated using commercial zeolites (ZSM-5, zeolite β, Mordenite, and USY), USY modified by ion-exchange, mixed catalyst (ZSM-5/ zeolite β, ZSM-5/USY), and nanocrystaline-ZSM-5. USY was modified by ion-exchange with ammonium salt at two different temperatures (298K and 353K) and for various reaction times. The cracking of PP and lldPE was performed using mixed catalysts and in addition a detailed study was carried out employing statistical design of response surface methodology to obtain the optimum reaction condition to produce maximum products. Nano crystalline ZSM-5 catalysts were prepared with/without the presence of alcohol (ethanol and isopropanol) and sodium and statistical analysis of completely random design was used to determine the effect of these constituents in the reaction mixture on the characteristics of ZSM-5 material and on their catalytic performance. The catalytic studies using commercial zeolites revealed that the zeolite β and mordenite produced higher liquid yield from lldPE and plastic waste, respectively. However, by using a modified USY, by ion-exchange at temperature 298K for 48hours, a further improvement to the liquid yield was achieved. Using a mixer of ZSM-5/ zeolite β it was possible to achieve very good conversions for both lldPE and PP with least amount of coke formation. Further studies on catalytic cracking of lldPE using nanocrystalline ZSM-5 indicate that the highest liquid yield that could be achieved was by using the material synthesised in the presence of alcohol and sodium in the starting solution. The effect of constituents in the starting gel mixture for ZSM-5 synthesis appears to influence surface area, acidity and particle size; however it appears that this does not affect the catalytic performance for cracking of lldPE. However the study suggest that control of external surface area and particle size is highly significant.
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Sundaralingam, Ramasubramanian. "Optimization of a model IV fluidized catalytic cracking unit." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58750.pdf.
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Idris, Muhammad Nuru. "Hydrodynamics and process modelling of fluid catalytic cracking reactors." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531527.
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Crynes, Lawrence Lee. "Development of a novel monolith froth reactor for three-phase catalytic reactions /." Access abstract and link to full text, 1993. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9412289.
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Yu, Joyleene Ruth. "Bio-oil upgrading through biodiesel emulsification and catalytic vapour cracking." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46841.
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With our limited fuel supplies struggling to keep up with our ever-increasing demand for energy, and the rising trend towards sustainable and cleaner technologies, the need to harness the potential of bio-oil as an alternative source of energy has never been more compelling. Although crude bio-oil can already be utilized to supplement heating oils and boiler fuels, its greater value lies in its potential as a source of transportation fuels and chemicals after upgrading.
In collaboration with Diacarbon Energy Inc., the main objectives of this project were twofold: (1) investigating the effect of extraction location from their proprietary pyrolysis unit on crude bio-oil quality prior to its emulsification with biodiesel, and characterizing the resulting biodiesel- and lignin-rich layers; and (2) designing and building a catalytic test unit to perform in situ cracking of slow pyrolysis vapours.
Experimental results confirmed that extraction location does affect the crude bio-oil quality. The effect of the surfactant on the emulsification was minimal as the resulting biodiesel-rich layer from the emulsification without the surfactant showed similar improvements in terms of water content, viscosity, TAN and HHV. A water mass balance confirmed that the majority of the water (~97%) is retained in the lignin-rich phase after emulsification. This is significant because the solvency of biodiesel can be utilized to upgrade bio-oils by selectively extracting its desirable fuel components into a biodiesel-rich phase, which can then be easily separated from the lignin- rich phase where the higher molecular weight compounds, such as pyrolytic lignin, as well as the majority of the water, are retained.
The bio-oil samples obtained from the non-catalytic and catalytic vapour cracking experiments separated into two distinct layers – an aqueous and organic layer. While the aqueous layers were fairly similar in nature, the organic layer from the catalytic experiment showed a significant decrease in viscosity (94.3% less) and water content (64.3% less). The organic layer from the catalytic pyrolysis remained homogeneous while that from the non-catalytic pyrolysis split into a hazy aqueous layer (with suspended oil droplets) sandwiched between a thin organic layer on top and a thicker organic layer at the bottom.
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Prado, Juan Luis Gomez. "Intergrated Methodology for the Modelling of Refinery Fluid Catalytic Cracking Units." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505488.
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Galligan, Carrie. "Catalytic Cracking of Jet Propellant-10. For Pulse Detonation Engine Applications." Thesis, Université Laval, 2005. http://www.theses.ulaval.ca/2005/22529/22529.pdf.
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Le carburant hydrocarbure JP-10 est étudié comme agent propulsif destiné aux
moteurs à détonation ainsi qu’à d’autres applications concernant les vols à vitesses
élevées. La précraquage catalytique du JP-10 pourrait produire un mélange d’oléfines
légères plus facile à détoner. Un mélange d’hydrocarbures aliphatiques, pour la plupart
légers, présente l’avantage d’être moins enclin à la carbonisation que des mélanges
comportant de fortes teneurs en hydrocarbures aromatiques. Cette réaction
endothermique de précraquage offre le même potentiel que celui d’un puits de chaleur
trouvé dans des applications de vols à vitesses élevées pour lesquelles toute hausse de
la masse du système de refroidissement contrevient à une plus grande efficacité du
moteur. Plusieurs essais de craquage catalytique hétérogène furent réalisés à l’aide
d’un réacteur tubulaire et les gaz produits analysés par GC/MS et par GC. Deux
formes de zéolithe nanocristalline (n) ZSM-5(24h) et nZSM-5 (6h) et trois formes de
silico-aluminophosphate SAPO-5A, SAPO-5B et SAPO-11 furent testées. SAPO-5 et
nZSM-5(24h) apparaissent être les candidats les plus propices au précraquage du
JP-10. Ces dernières ont permis de convertir plus de 90 % de JP-10 en un mélange
d’hydrocarbures principalement composé de molécules en C4 et moins (C3 à C1).
nZSM-5(24h) ont procuré le plus petit rapport de masse de carbone, CR (C5+:C4−),
à des températures situées entre 350 oC et 450 oC et le taux de conversion le plus
élevé à des températures supérieures à 500 oC. SAPO-5A & B ont présenté le taux de
conversion le plus élevé mais le plus petit CR entre 400 oC et 500 oC.The hydrocarbon jet-fuel, JP-10, is being studied as a possible propellant for the Pulse Detonation Engine (PDE) and other high-speed flight applications. Catalytic pre-cracking of JP-10 could provide a more easily detonated mixture of light olefin products. A mixture of mostly light hydrocarbons has the added benefit of being less prone to coking than a product mixture heavy in aromatics. This endothermic reaction also offers potential as a heat sink in high-speed flight applications where the extra weight of an onboard cooling system would hinder engine efficiency. Several heterogeneous catalytic cracking tests have been done using a Bench Top Tubular Reactor and the products were analyzed with GC/MS and GC. Two forms of nanocrystalline zeolites, nZSM-5(24h) and nZSM-5(6h), and three forms of silico-alumino-phosphates, SAPO-5A, SAPO-5B, and SAPO-11 successfully catalyzed the cracking of JP-10; however, SAPO-5 and nZSM-5(24h) have proven to be the most promising catalyts. Both catalysts converted over 90 % of JP-10 (∼ 3s residence time) into a mixture of hydrocarbon products consisting mainly of C4 and lower chain hydrocarbons (C3 to C1). nZSM-5(24h) demonstrated the lowest carbon mass ratio, CR (C5+:C4−), between 350 oC and 450 oC and the highest conversion rates above 500 oC. SAPO-5A & B demonstrated the highest conversion rates and the lowest CR between 400 oC and 500 oC.
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Panpranot, Joongjai. "Hydrothermal aging of zeolite-based catalysts." Morgantown, W. Va. : [West Virginia University Libraries], 1998. http://etd.wvu.edu/templates/showETD.cfm?recnum=274.
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Thesis (M.S.)--West Virginia University, 1998.Title from document title page. Document formatted into pages; contains xi, 84 p. : ill. Includes abstract. Includes bibliographical references (p. 64-67).
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Bayraktar, Oguz. "Effect of pretreatment on the performance of metal contaminated commercial FCC catalyst." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2071.
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Thesis (Ph. D.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xvi, 214 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 199-208).
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Madadkhani, Shiva. "Red mud as an iron-based catalyst for catalytic cracking of naphthalene." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/60118.
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Reducing the tar content in the producer gas of biomass gasification processes remains one of the main challenges in the commercialization of this technology and, hence, the development of clean and economical tar-removing technologies is becoming increasingly important. Catalytic tar removal has the advantage of avoiding expensive gas cleaning systems while maintaining the sensible heat in the producer gas. Commercial catalysts based on noble metals and metal oxides have shown good activity towards tar destruction, but are prone to rapid deactivation. This in addition to the high replacement cost provide the rationale for the development of low-cost alternatives. Red mud, a by-product from bauxite processing, has received considerable attention in this regard due to its high iron content in the form of ferric oxide (Fe₂O₃), high surface area, and its resistance to sintering and poisoning. However, very few studies have been conducted to investigate red mud as a potential catalyst for catalytic tar removal. The aim of this study was to develop a catalyst from red mud for the removal of naphthalene, as a model compound for gasification tar. Red mud catalyst pellets were produced from raw red mud slurry, and their properties were investigated by measuring the chemical composition, surface area, and pore size distribution. Subsequently, the ability for tar decomposition was studied by passing naphthalene-nitrogen and naphthalene-hydrogen mixtures through a bed of the catalyst at five space velocities in the range of 4500-19,000 h-¹, and at reactor temperatures of 500, 600, 700 and 800°C. Catalytic cracking tests confirmed that red mud possesses a very high intrinsic catalytic activity for naphthalene conversion even at temperatures as low as 500°C and space velocities as high as 19,000 h-¹. Kinetic analysis was also performed to determine the apparent reaction order, the kinetic rate constants as well as the activation energy of the reaction. Long term tests of the catalyst showed that the activity of the catalyst diminished over time when no hydrogen was present in the system; however, in the presence of H₂ the activity was found to remain > 90% for 14 h.Applied Science, Faculty of
Graduate
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Yateem, Wael. "Environmental impact of fluid catalytic cracking unit in a petroleum refining complex." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8340.
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The fluid catalytic cracking (FCC) unit is of great importance in petroleum refining industries as it treats heavy fractions from various process units to produce light ends (valuable products). The FCC unit feedstock consists of heavy hydrocarbon with high sulphur contents and the catalyst in use is zeolite impregnated with rare earth metals i.e. lanthanum and cerium oxides. The catalytic cracking reaction is endothermic and takes place at elevated temperature in a fluidised bed reactor generating sulphur-contaminated coke on the catalyst. In the regenerator, coke is completely burnt producing SO2, particulate matter emissions. The impact of the FCC unit is assessed in the immediate neighborhood of the refinery. Emission inventories for years 2008 and 2009 for both SO2 and PM have been calculated based on real operational data. Comprehensive meteorological data for years 2005 – 2009 are obtained and preprocessed to generate planetary boundary layer parameters using Aermet (Aermod preprocessor). Aermod (US EPA approved dispersion model) is applied to predict ground level concentrations of both pollutants in the selected study area. Model output is validated with the corresponding measured values at discrete receptors. The highest hourly SO2 predicted concentrations for both years 2008 and 2009 exceeded the corresponding Kuwait EPA ambient air standard, mainly due to elevated emission rates and the prevailing calm and other meteorological conditions. The highest daily SO2 predicted concentrations also exceeded the Kuwait EPA allowable limit due to high emission rates, while meteorological parameters influence is dampened. Hourly average predicted PM concentrations showed similar variation into SO2 in different location. The daily average predicted PM concentrations are lower than US EPA specified limit. An extensive parametric study has been conducted using three scenarios, stack diameter, stack height and emission rates. It is noticed that stack diameter has no effect on ground level concentration, as stack exit velocity is a function of the square of stack diameter. With the increase in stack height, the predicted concentrations decrease showing an inverse relation. The influence of the emission rate is linearly related to the computed ground level concentrations SO2 additives are tested for SO2 emissions reduction. In the year 2008, reduction of SO2 annual total emission by 43% results in full compliance with Kuwait EPA hourly specified limit, using an appropriate amount of additives. Similarly, 57% reduction of SO2 annual total emission leads to no exceedance in predicted concentrations for the year 2009. The application of the state of the art technology, ESP has reduced about 90% of PM emissions for the year 2009.
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Shehab, Amal. "The role of carbon in the catalytic isomerisation-cracking of n-alkanes." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21028/.
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The isomerisation-cracking of n-alkanes is one of the important processes in the refining and petrochemical industries. It is considered as a sustainable process where low value hydrocarbons are upgraded into value added products. Zeolites, and metal modified zeolites, are widely utilised as solid acid catalysts in such reactions, with metals such as platinum providing the functionality to effectively dissociate hydrogen. Catalyst deactivation by coke formation is however a crucial concern associated with hydrocarbon transformations over such catalysts. Nevertheless, recent studies have shown that these carbonaceous deposits, in addition to being implicated in catalyst deactivation, may have a beneficial or an active role in enhancing the catalytic performance. The main focus of this thesis is to understand the role of coke in the catalytic isomerisation-cracking of n-alkanes and to explore how a controlled pre-coking treatment can be used to enhance catalytic performance. Specifically, this thesis investigates the role of carbonaceous deposits in the isomerisation-cracking of n-pentane and n-hexadecane over the metal modified zeolite Pt/H-Beta. Carbon laid down during n-pentane isomerisation over Pt/H-Beta is shown to as a catalytically beneficial species by control coking reactions and enhancing the selectivity to iso-pentane. These carbonaceous species are predominantly composed of polyaromatic compounds in graphitic-like structures. In n-hexadecane conversion over Pt/H-Beta, cracking is favoured over isomerisation and carbonaceous deposits are formed rapidly causing catalyst pore blockage. Reactions over Pt/H-Beta modified by desilication revealed that coke formation is due to the retention of reaction intermediates and/or products inside the pores, resulting in improved selectivity to iso-hexadecane production over the modified catalyst, with carbon deposition significantly reduced. n-Hexadecane conversion performed over Pt/H-Beta pre-coked with n-pentane or toluene as paraffinic and aromatic precursors respectively, showed that selectivity to short-chained alkanes (pentane, hexane, and heptane) can be enhanced by tailored-carbon deposition. These products are highly in demand in petrochemical industry for the production of commercial fuels and solvents. Additionally, the rate of coke formation is remarkably reduced, in particular over toluene pre-coked Pt/H-Beta where the internal sites are blocked by carbonaceous species. In general, tailored carbon deposition can be considered as a useful approach to maximise the production of short-chained hydrocarbons from heavy feedstocks and minimise the coking rate.
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Aldawsari, Afrah M. F. "Dielectric measurements and catalytic cracking of heavy oils using advanced microwave technologies." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:af211e33-c6a7-4fb3-8a91-47b0f7f677bc.
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The continuously growing world demands of petroleum to service the domestic and industrial electricity, transportation sectors, and its contribution to Climate Change, places onus on researchers to find more efficient methods for heavy oil (petroleum) processing. Given the enormous quantities of petroleum processed in the world, and the general prevalence of high energy cost and high carbon footprint processing technologies, there is strong interest in development of more efficient and improved unconventional processing methods. This thesis contributes to the field of unconventional processing methods for petroleum. We investigate the utility of microwave irradiation for efficient chemical activation for the processing of petroleum to useful products, and demonstrate that the selective and targeted dissipation of microwave energy has great potential to deliver shorter reaction times compared to conventional cracking processes driven by thermal energy. Heavy bunker oil, which is the starting feedstock for petroleum processing, is a thick and viscous material. Furthermore, it is not a good absorber of microwave energy due to the presence of nonpolar heavy fractions such as hydrocarbons, sulphur, and nitrogen compounds. Such characteristics make microwave processing of petroleum especially challenging. As the essential first step, the elucidation of microwave response properties of petroleum is one of the key outcomes of this thesis. This was accomplished by a systematic investigation of dielectric properties of model chemical compounds and oil samples using the cavity perturbation technique at 2.45 GHz. The zeolite HZSM-5 is widely recognized among the best catalysts for the production of high value light products from petroleum, and was employed for our studies. The dielectric properties of the zeolite were evaluated at room, and at higher temperatures up 500°C to gain insight into the behaviour of the sample (catalyst and oil) in a microwave energy driven catalytic cracking reaction. Generally, we found that the permittivity of the zeolite increases as the temperature increases. We attribute this to the enhancement in polarisation, as well as to a temperature dependent microwave conductivity, which occurs via proton hopping mechanism. We have systematically explored libraries of dielectric materials to understand the materials interaction with microwave energy. This has allowed us to investigate the variation of microwave energy dissipation and cracking reactions for various catalyst-petroleum systems. The optimisation of microwave applicator parameters using a model compound (decane) was performed. This indicated a clear diffierence in product distribution between thermal and microwave processing and an enhanced fraction of hydrogen and olefins were observed under microwave irradiation. We ascribe this observation to the difference in heat generation mechanism between the two modes. The microwave applicator was used to study heavy oil cracking it was found it is possible to conduct an efficient cracking reaction over appropriately modified zeolite. We should particularly highlight our results, whereby we demonstrate the production of large fraction of hydrogen over metal oxide doped HZSM-5 zeolite. It was found that the cracking reactions of the heavy oil over zeolite are influenced by the high electric field, which can result in highly localised superheating within the catalytic material. The heavy oil impregnated metal oxide-zeolite displayed significant temperature gradients between the catalyst particles hotspot and the surrounding domains compared to the non-modified zeolite. Thus, the dehydrogenation process and the release of hydrogen were found to be enhanced in the decomposition of metal oxide-HZSM-5 zeolite compared to the pure HZSM-5. Further enhancement of our system to a continuous flow reaction was performed in order to assess the potential for industrial applications of heavy oil cracking processes using microwave technology. This would be a critical step to demonstrate the scalability of our techniques. However, the results presented in this thesis reliably demonstrate that a significantly enhanced performance at lab scale system in shorter reaction times could be achieved through the cracking of heavy oil to hydrogen and high value light products.
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Añez, Javier. "Modélisation de l'injection de pétrole pour les procédés FCC (Fluid Catalytic Cracking)." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR132/document.
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Cette thèse est une entreprise commune de VINCI Technologies et du laboratoire CNRS CORIA. De nombreux injecteurs comportent une zone de mélange interne dans laquelle les phases liquides et gazeuses sont toutes deux présentes dans une proportion significative. Par conséquent, cette zone appartient à la catégorie des écoulements diphasiques denses. Pour simuler la dispersion du liquide et caractériser le spray de ces injecteurs, des modèles appropriés sont nécessaires. Les points clés de cette approche sont la dispersion du liquide qui peut être associé au flux liquide turbulent et la quantité de surface liquide-gaz. En particulier, ce manuscrit rapporte, d’une part le développement théorique des modèles de la famille ELSA et, d’autre part, les approximations industrielles correspondantes. Le solveur proposé bascule dynamiquement du spray ICM au spray de sous- maille, à travers le concept ELSA et grâce à l’indicateur basé sur la résolution (IRQ). D’autre part, une fois la zone diluée se forme, l’approche ELSA est couplée à la méthode d’écoulement multiphase, qui vise à déterminer la distribution du spray à l’aide de l’équation WBE. Cette dernière équation est résolue avec une méthode hybride Euler-Lagrange. Le but est de résoudre l’équation WBE avec une approche stochastique Lagrangienne, tout en préservant la compatibilité avec la description Eulerienne de l’écoulement diphasique, basée sur ELSA, pour tirer parti des deux approches. Finalement, ces approches développées ont été utilisées pour des applications industrielles montrant leur robustesse et leur capacité à aider dans le processus de développement de nouveaux injecteursThis PhD is a joint venture between VINCI Technologies and the CNRS Laboratory CORIA. For its application, VINCI Technologies, developed mainly oil-related equipments and in particular injection/atomization systems. Some of these injectors are characterized by a very big geometrical dimensions (several meters long), that leads to very high Reynolds and Weber number. In addition, many injectors incorporate an internal mixing zone, in which liquid and gas phases are both present in a significant proportion. Consequently, this zone belongs to the dense two-phase flow category. To simulate the liquid dispersion and to characterize the spray formation special from these injectors, appropriate models are required. On its side, the CORIA team, has developed a suitable approach, so-called ELSA, based on the pioneering work of Borghi and Vallet [1, 2]. Key points of this approach are the liquid dispersion that can be associated to the turbulent liquid flux and the amount of liquid-gas surface that can be used to determine eventually the Sauter mean diameter (SMD) of the spray. During this PhD, the applications proposed by V INCI Technologies, have promoted a review of a large part of the multiphase flow approaches to find the more appropriate for each case. This has been the opportunity to clarify the range of application of each approach, and therefore stress the necessity to develop coupled approaches, in order to cover the proposed application in the most suitable way. In particular, this manuscript reports, in one hand, the theoretical development of the ELSA family models, and on the other hand, the corresponding industrial approximations. Since ELSA approaches are originally developed for RANS simulation of the dense zone, it has been extended to LES description. The link of this approach to the DNS¡ ICM approach, has been studied with a special care. The resulting proposed solver, switches dynamically from ICM to subgrid spray, through the ELSA concept, and thanks to resolution based indicator (IRQ). On the opposite side, once the dispersed spray is formed, the ELSA approach is coupled to multiphase flow method, that aims to determine the spray distribution through the WBE equation. This later equation, is solved with an original hybrid Euler-Lagrange method. The purpose is to solve the WBE equation with a Lagrange stochastic approach, and at the same time, preserving the compatibility to the Euler description of two-phase flow, based on ELSA, to benefit from both approaches. This coupled approach has been tested against academic experimental data coming from ECN research initiative, a combined DNS and experimental measurement of dispersed spray on a Diesel jet, and under an air-blast atomizer numerical test case, for which the mean liquid volume fraction has been measured. Eventually, these developed approaches have been applied to industrial application showing there robustness and their capacity to help in the process of design development of new injectors
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Brillis, Aristidis. "Catalytic cracking of C8 aliphatic hydrocarbons over ultrastable Y zeolite and its deactivation." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272152.
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Smith, Gordon Christopher. "Catalytic cracking of n-alkanes and n-alkylbenzenes over H-ZSM-5 zeolite." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12550.
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Dufreche, Stephen Thomas. "Effect of phosphorous poisoning on catalytic cracking of lipids for green diesel production." Diss., Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-04022008-220330.
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Zheng, Xiaobo. "A Computational Investigation of Hydrocarbon Cracking: Gas Phase and Heterogeneous Catalytic Reactions on Zeolites." Diss., Tucson, Arizona : University of Arizona, 2006. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1455%5F1%5Fm.pdf&type=application/pdf.
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Alsabei, Redah Mousa. "Model-based approach for the plant-wide economic control of fluid catalytic cracking unit." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8566.
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Fluid catalytic cracking (FCC) is one of the most important processes in the petroleum refining industry for the conversion of heavy gasoil to gasoline and diesel. Furthermore, valuable gases such as ethylene, propylene and isobutylene are produced. The performance of the FCC units plays a major role on the overall economics of refinery plants. Any improvement in operation or control of FCC units will result in dramatic economic benefits. Present studies are concerned with the general behaviour of the industrial FCC plant, and have dealt with the modelling of the FCC units, which are very useful in elucidating the main characteristics of these systems for better design, operation, and control. Traditional control theory is no longer suitable for the increasingly sophisticated operating conditions and product specifications of the FCC unit. Due to the large economic benefits, these trends make the process control more challenging. There is now strong demand for advanced control strategies with higher quality to meet the challenges imposed by the growing technological and market competition. According to these highlights, the thesis objectives were to develop a new mathematical model for the FCC process, which was used to study the dynamic behaviour of the process and to demonstrate the benefits of the advanced control (particularly Model Predictive Control based on the nonlinear process model) for the FCC unit. The model describes the seven main sections of the entire FCC unit: (1) the feed and preheating system, (2) reactor, (3) regenerator, (4) air blower, (5) wet gas compressor, (6) catalyst circulation lines and (7) main fractionators. The novelty of the developed model consists in that besides the complex dynamics of the reactorregenerator system, it includes the dynamic model of the fractionator, as well as a new five lump kinetic model for the riser, which incorporates the temperature effect on the reaction kinetics; hence, it is able to predict the final production rate of the main products (gasoline and diesel), and can be used to analyze the effect of changing process conditions on the product distribution. The FCC unit model has been developed incorporating the temperature effect on reactor kinetics reference construction and operation data from an industrial unit. The resulting global model of the FCC unit is described by a complex system of partial-differential-equations, which was solved by discretising the kinetic models in the riser and regenerator on a fixed grid along the height of the units, using finite differences. The resulting model is a high order DAE, with 942 ODEs (142 from material and energy balances and 800 resulting from the discretisation of the kinetic models). The model offers the possibility of investigating the way that advanced control strategies can be implemented, while also ensuring that the operation of the unit is environmentally safe. All the investigated disturbances showed considerable influence on the products composition. Taking into account the very high volume production of an industrial FCC unit, these disturbances can have a significant economic impact. The fresh feed coke formation factor is one of the most important disturbances analysed. It shows significant effect on the process variables. The objective regarding the control of the unit has to consider not only to improve productivity by increasing the reaction temperature, but also to assure that the operation of the unit is environmentally safe, by keeping the concentration of CO in the stack gas below a certain limit. The model was used to investigate different control input-output pairing using classical controllability analysis based on relative gain array (RGA). Several multi-loop control schemes were first investigated by implementing advanced PID control using anti-windup. A tuning approach for the simultaneous tuning of multiple interacting PID controllers was proposed using a genetic algorithm based nonlinear optimisation approach. Linear model predictive control (LMPC) was investigated as a potential multi-variate control scheme applicable for the FCCU, using classical square as well as novel non-square control structures. The analysis of the LMPC control performance highlighted that although the multivariate nature of the MPC approach using manipulated and controlled outputs which satisfy controllability criteria based on RGA analysis can enhance the control performance, by decreasing the coupling between the individual low level control loops operated by the higher level MPC. However the limitations of using the linear model in the MPC scheme were also highlighted and hence a nonlinear model based predictive control scheme was developed and evaluated.
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Barth, Jan O. [Verfasser]. "Novel nanocomposite catalysts for NOx reduction from Fluid Catalytic Cracking units / Jan O Barth." Aachen : Shaker, 2003. http://d-nb.info/1170544029/34.
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Bruening, Christopher. "Decalin Dehydrogenation for In-Situ Hydrogen Production to Increase Catalytic Cracking Rate of n-Dodecane." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1525100991525704.
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Wallace, Carol Leigh. "The investigation into the formation of coke in relation to the fluid catalytic cracking process." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248295.
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Beskari, Mohamed Ali. "Dynamic analysis of diffusion and convection in porous catalysts." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244857.
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Illes-Smith, Peter C. "A study of the modelling, dynamic simulation and control of the modern fluid catalytic cracking process." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330143.
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Gholizadeh, Mortaza. "Upgrading of pyrolysis bio-oil through hydrodeoxygenation and cracking in a continuous packed-bed catalytic reactor." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1761.
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Biomass is the only renewable resource that can be used to produce liquid fuels. The pyrolysis of biomass produces a crude bio-oil liquid. This study investigated the catalytic hydrotreatment of bio-oil to produce advanced liquid biofuels. The study focused on the understanding of reaction mechanisms for the formation of light fuel species and solid coke. The results will be useful for the development of low-emission biofuel technologies using non-food lignocellulosic biomass resources.
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Malgarinos, Ilias. "Development of a two-phase flow model for the investigation of collisions between heavy gasoil doplets and catalytic particles in Fluid Catalytic Cracking Reactors." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/19271/.
Full textAbstract:
The goal of this work is to study computationally the flow induced by the collision between a single gasoil droplet and a spherical catalytic particle under realistic Fluid Catalytic Cracking (FCC) conditions. FCC reactors are found in the fossil fuel refineries and are used to upgrade heavy fuel (gas oil) to lighter products (gasoline or LPG), which are industrially more important. Gasoil is injected in the reactor and atomizes; the produced droplets vaporize intensely and come in contact with the hot fluidized solid catalysts. The “cracking” reactions accommodated at the particle porous surface (ex. zeolite) result in the decomposition of gasoil to lighter products. The two-phase flow model developed solves the incompressible Navier-Stokes equations for mass and momentum, along with the energy conservation equation. The VOF methodology is used to track the liquid-gas interface, while a dynamic local grid refinement technique is adopted, so that high accuracy is achieved with a relative low computational cost. A local evaporation model coupled with the additional solution of the species transport equation is utilized to consider phase change. Cracking surface reactions are taken into account via a simplified 2-lump scheme. The model is successfully validated in fundamental droplet dynamics flow conditions, such as droplet acceleration, droplet impingement onto flat and solid surfaces under isothermal conditions and droplet evaporation. Insights into these phenomena provide important information that are missing from experimental measurements. The numerical novelties of the current work include the implementation of a new Wetting Force Model to simulate drop-solid interaction, as well as the proposition of a sharpening scheme for the volume fraction field, to suppress diffusion. Concerning FCC collisions, the numerical model is able to reproduce both the hydrodynamics (drop deformation, spreading, breakup), as well as the chemical products (gasoil converted to gasoline). It is found that droplets of similar size to the catalytic particles tend to be levitated more easily by hot catalysts, thus resulting in higher cracking reaction rates/cracking product yield, and limited possibility for liquid pore blocking. For larger sized droplets, solid-liquid contact increases. The main ambition of the current Thesis, which is to combine the droplet hydrodynamics with the chemical reactions acts as a novel step towards the understanding of such micro-scale physical phenomena that are difficult to capture/measure in experimental apparatus. This fundamental numerical tool can provide insight to the spray system strategy of an FCC reactor for a wide range of operating conditions.
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Silva, German Gonzalez. "Modelagem e simulação de reatores gas-solido de escoamento descendente (Downer)." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266438.
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Orientador: Antonio Carlos Luz LisboaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Os reatores de leito fluidizado são uma das mais importantes tecnologias atuais para processos heterogêneos gás-sólido, tanto catalíticos como não catalíticos. As aplicações industriais mais importantes incluem o craqueamento catalítico na indústria petroquímica, a combustão e/ou gaseificação de carvão, biomassa e resíduos sólidos. Estes são importantes processos para a geração de energia, produção de combustíveis e gás de síntese. Um dos tipos de reatores de leito fluidizado mais relevante é o reator de fluxo ascendente conhecido como riser. Este reator consiste de uma coluna tubular na qual o sólido e o gás escoam co-correntes de forma ascendente. Em comparação com outras tecnologias, o reator riser tem uma importante desvantagem: uma distribuição de tempos de residência variada no reator que reduz a conversão e a seletividade. Recentemente cresceu o interesse por outro tipo de reator gás-sólido circulante que possui melhor desempenho que o reator riser. Neste tipo de reator, conhecido como downer, por oposição ao riser, o escoamento co-corrente gás-sólido ocorre de forma descendente, o que lhe outorga características fluidodinâmicas que se assemelham mais ao escoamento tipo pistão e permitem um melhor controle da conversão, da seletividade e da desativação. O objetivo deste trabalho é estudar a simulação de reatores gás-sólido tipo downer, incorporando modelos fluidodinâmicos com modelos de engenharia das reações químicas e catalíticas. Desenvolve-se, de forma geral, a modelagem dos diferentes fenômenos fluidodinâmicos, físico-químicos e catalíticos que ocorrem no reator e são propostos algoritmos de solução para diferentes situações. Posteriormente, aplica-se o modelo proposto do reator downer ao estudo de um caso industrial: o craqueamento catalítico. Os resultados mostram um enfoque geral aplicável para a modelagem e simulação de sistemas de reações gás-sólido em fluxo descendente. As simulações do processo industrial de craqueamento catalítico revelam que o reator tipo downer apresenta características de desempenho que o fazem superior ao reator tipo riser convencional.
Abstract: The fluidized bed reactor is one of the most important technologies for gas-solid heterogeneous operations, considering catalytic or non catalytic processes. The most important industrial applications include catalytic cracking, coal combustion and biomass combustion. The most relevant fluidized bed reactor is the ascendant flow reactor, which is known as riser. The riser reactor consist of a tubular column in which the solid and the gas flow cocurrently upward. The riser reactor has as main disadvantage a wide residence time distribution, which reduce the conversion and the selectivity. Recently, it has grown the interest in a new type of gas-solid circulating reactor with a better performance than the riser which is known as downer. In this reactor the gas and the solid flow cocurrently downward, creating hydrodynamic features comparable to a plug flow reactor and allowing a better control over the conversion, the selectivity and the deactivation. This work regarded it had been studied the simulation of the gas-solid downer reactor, including hydrodynamic models and models from the chemical reaction engineering. It was developed in a general way the modelling of the hydrodynamic, physical chemical and catalytic phenomena occurring in the reactor. Algorithms were proposed to solve of different simulation cases. The proposed model of the downer reactor was used in the studying of one industrial case: the catalytic cracking. The results show a general approach which is applicable for modelling and simulation of gas-solid reactive system with descendent flow. The simulations of the catalytic cracking show that the downer reactor has features that make it perform better than the conventional riser reactor.
Mestrado
Engenharia de Processos
Mestre em Engenharia Química
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John, Yakubu M. "Kinetic modelling simulation and optimal operation of fluid catalytic cracking of crude oil: Hydrodynamic investigation of riser gas phase compressibility factor, kinetic parameter estimation strategy and optimal yields of propylene, diesel and gasoline in fluid catalytic cracking unit." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17323.
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The Fluidized Catalytic Cracking (FCC) is known for its ability to convert refinery wastes into useful fuels such as gasoline, diesel and some lighter products such as ethylene and propylene, which are major building blocks for the polyethylene and polypropylene production. It is the most important unit of the refinery. However, changes in quality, nature of crude oil blends feedstock, environmental changes and the desire to obtain higher profitability, lead to many alternative operating conditions of the FCC riser.
There are two major reactors in the FCC unit: the riser and the regenerator. The production objective of the riser is the maximisation of gasoline and diesel, but it can also be used to maximise products like propylene, butylene etc. For the regenerator, it is for regeneration of spent or deactivated catalyst.
To realise these objectives, mathematical models of the riser, disengage-stripping section, cyclones and regenerator were adopted from the literature and modified, and then used on the gPROMS model builder platform to make a virtual form of the FCC unit. A new parameter estimation technique was developed in this research and used to estimate new kinetic parameters for a new six lumps kinetic model based on an industrial unit. Research outputs have resulted in the following major products’ yields: gasoline (plant; 47.31 wt% and simulation; 48.63 wt%) and diesel (plant; 18.57 wt% and simulation; 18.42 wt%) and this readily validates the new estimation methodology as well as the kinetic parameters estimated. The same methodology was used to estimate kinetic parameters for a new kinetic reaction scheme that considered propylene as a single lump. The yield of propylene was found to be 4.59 wt%, which is consistent with published data.
For the first time, a Z-factor correlation analysis was used in the riser simulation to improve the hydrodynamics. It was found that different Z factor correlations predicted different riser operating pressures (90 – 279 kPa) and temperatures as well as the riser products. The Z factor correlation of Heidaryan et al. (2010a) was found to represent the condition of the riser, and depending on the catalyst-to-oil ratio, this ranges from 1.06 at the inlet of the riser to 0.92 at the exit.
Optimisation was carried out to maximise gasoline, propylene in the riser and minimise CO2 in the regenerator. An increase of 4.51% gasoline, 8.93 wt.% increase in propylene as a single lump and 5.24 % reduction of carbon dioxide emission were achieved. Finally, varying the riser diameter was found to have very little effect on the yields of the riser products.
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Conti, Roberto <1986>. "Analytical Pyrolysis and Microextraction Methods to Characterize Oil and Biochar from Thermal and Catalytic Cracking of Biomass." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7320/1/Conti_Roberto_Tesi.pdf.
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In this dissertation thermal and catalytic pyrolysis of protein-rich biomass was investigated. The study was focused on the liquid and solid products. This thesis was aimed to gather chemical information on the thermal behavior of proteinaceous substrates in the presence of zeolite and compare with lignocellulosic biomass. Furthermore, the thesis was focused on the development of reliable analytical methods by means of Py-GC-MS in order to predicting bio-oil composition and to investigating biochar structure and its correlation with thermal stability. In addition a sampling procedure for the direct analysis of pyrolysis vapours based on absorption onto a microfiber (SPME) was developed.
Py-GC-MS was applied as screening method to study the effect of different catalysts (H-ZSM5, MCM-41) and biomass-catalyst weight ratio on aromatic hydrocarbons production.
The obtained results demonstrated that Py-GC-MS enable the selection of pyrolysis conditions. H-ZSM5 confirmed to be the catalyst with the best performance in terms of hydrocarbon production. In addition, the chemical composition observed by Py-GC-MS significantly reflects that obtained on bench scale. However, some difference has been found. Indeed, formation of high molecular weight PAHs have been observed only on bench scale and nitrogen-containing compounds and oxygenated compounds exhibited some difference related to condensation step. Problems during condensation step led to using SPME as at-line monitoring technique during the process capable of hot gas phase analysis. Strong similarity between GC-MS analysis of hot vapours and bio-oil from condensation traps were found.
Finally, Py-GC-MS was applied to the chemical characterization of biochars obtained under different pyrolysis conditions or from different feedstock.
Py-GC-MS can provide molecular indices useful to gather information on biochar thermal stability and to predicting the biochar carbonization degree. Furthermore, the molecular pattern resulting from Py-GC-MS could be utilized to infer information on the nature of the initial substrate and differentiate biochars.
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Conti, Roberto <1986>. "Analytical Pyrolysis and Microextraction Methods to Characterize Oil and Biochar from Thermal and Catalytic Cracking of Biomass." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7320/.
Full textAbstract:
In this dissertation thermal and catalytic pyrolysis of protein-rich biomass was investigated. The study was focused on the liquid and solid products. This thesis was aimed to gather chemical information on the thermal behavior of proteinaceous substrates in the presence of zeolite and compare with lignocellulosic biomass. Furthermore, the thesis was focused on the development of reliable analytical methods by means of Py-GC-MS in order to predicting bio-oil composition and to investigating biochar structure and its correlation with thermal stability. In addition a sampling procedure for the direct analysis of pyrolysis vapours based on absorption onto a microfiber (SPME) was developed.
Py-GC-MS was applied as screening method to study the effect of different catalysts (H-ZSM5, MCM-41) and biomass-catalyst weight ratio on aromatic hydrocarbons production.
The obtained results demonstrated that Py-GC-MS enable the selection of pyrolysis conditions. H-ZSM5 confirmed to be the catalyst with the best performance in terms of hydrocarbon production. In addition, the chemical composition observed by Py-GC-MS significantly reflects that obtained on bench scale. However, some difference has been found. Indeed, formation of high molecular weight PAHs have been observed only on bench scale and nitrogen-containing compounds and oxygenated compounds exhibited some difference related to condensation step. Problems during condensation step led to using SPME as at-line monitoring technique during the process capable of hot gas phase analysis. Strong similarity between GC-MS analysis of hot vapours and bio-oil from condensation traps were found.
Finally, Py-GC-MS was applied to the chemical characterization of biochars obtained under different pyrolysis conditions or from different feedstock.
Py-GC-MS can provide molecular indices useful to gather information on biochar thermal stability and to predicting the biochar carbonization degree. Furthermore, the molecular pattern resulting from Py-GC-MS could be utilized to infer information on the nature of the initial substrate and differentiate biochars.
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Al-Rubaye, Rana. "Generation and characterisation of catalytic films of zeolite Y and ZSM-5 on FeCrAlloy metal." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/generation-and-characterisation-of-catalytic-films-of-zeolite-y-and-zsm5-on-fecralloy-metal(de743286-52bd-4922-8de7-9a261283b6e5).html.
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The objective of this work was the development of structured zeolite catalysts by growing of ZSM-5 and Y zeolites layers on the pre-treated FeCrAlloy wires, which could now offer technical advantage in catalytic application. The advantages of implementation of zeolitic coatings in industrial applications are that they have; lower pressure drop, high heat and mass transfer rates compared to standard pelleted or extruded catalysts. The key focus of this research was the generation of thin films of zeolite ZSM–5 and Y zeolite catalysts on the surface of a FeCrAlloy metal substrate. Using in-situ hydrothermal synthesis, the influence of the synthesis parameters such as substrate oxidation and crystallisation time on the zeolite crystallisation process in both the bulk phase (powder) and on the structured zeolite was studied and optimised. Then powder and structured Na-ZSM-5 and Na-Y were treated by calcination and ion exchange in post-synthesis treatment. Further post-synthesis modification was required in the zeolite Y case to improve the catalytic properties. The post synthetic modification of zeolite Y was carried out using acidified ammonium nitrate which was optimised to produce dealuminated zeolite Y with good crystallinity and a Si/Al = 8. Characterisation was performed after each stage of this work to optimise catalyst development using XRD, SEM, EDAX, BET, MAS-NMR, and TGA. Once the optimised zeolite Y and ZSM-5 structured catalysts prepared, cracking of n-heptane was carried out to assess the in catalytic performance compared with Y and ZSM-5 pellets in a fixed-bed reactor under the same operation conditions. The cracking of n–heptane over the pellets and structured catalysts for both ZSM–5 and Y zeolite showed very similar product selectivities for similar amounts of catalyst with apparent activation energy of around 60 kJ mol-1. This research demonstrates that structured catalysts can be manufactured with excellent zeolite adherence and when suitably activated/modified give comparable cracking results to the pelleted powder forms. These structured catalysts will improve temperature distribution in highly exothermic and endothermic catalysed processes.
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Hörnell, Christina. "Thermochemical and Catalytic Upgrading in a Fuel Context : Peat, Biomass and Alkenes." Doctoral thesis, KTH, Chemical Engineering and Technology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3164.
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Pashikanti, Kiran. "Predictive Modeling of Large-Scale Integrated Refinery Reaction and Fractionation Systems from Plant Data: Fluid Catalytic Cracking (FCC) and Continuous Catalyst Regeneration (CCR) Catalytic Reforming Processes." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77181.
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This dissertation includes two accounts of rigorous modeling of petroleum refinery modeling using rigorous reaction and fractionation units. The models consider various process phenomena and have been extensively used during a course of a six-month study to understand and predict behavior. This work also includes extensive guides to allow users to develop similar models using commercial software tools.
(1) Predictive Modeling of Large-Scale Integrated Refinery Reaction and Fractionation Systems from Plant Data: Fluid Catalytic Cracking (FCC) Process with Planning Applications: This work presents the methodology to develop, validate and apply a predictive model for an integrated fluid catalytic cracking (FCC) process. We demonstrate the methodology by using data from a commercial FCC plant in the Asia Pacific with a feed capacity of 800,000 tons per year. Our model accounts for the complex cracking kinetics in the riser-regenerator and associated gas plant phenomena. We implement the methodology with Microsoft Excel spreadsheets and a commercial software tool, Aspen HYSYS/Petroleum Refining from Aspen Technology, Inc. The methodology is equally applicable to other commercial software tools. This model gives accurate predictions of key product yields and properties given feed qualities and operating conditions. This work differentiates itself from previous work in this area through the following contributions: (1) detailed models of the entire FCC plant, including the overhead gas compressor, main fractionator, primary and sponge oil absorber, primary stripper and debutanizer columns; (2) process to infer molecular composition required for the kinetic model using routinely collected bulk properties of feedstock; (3) predictions of key liquid product properties not published alongside previous related work (density, D-86 distillation curve and flash point); (4) case studies showing industrially useful applications of the model; and (5) application of the model with an existing LP-based planning tool.
(2) Predictive Modeling of Large-Scale Integrated Refinery Reaction and Fractionation Systems from Plant Data: Continuous Catalyst Regeneration (CCR) Reforming Process: This work presents a model for the rating and optimization of an integrated catalytic reforming process with UOP-style continuous catalyst regeneration (CCR). We validate this model using plant data from a commercial CCR reforming process handling a feed capacity of 1.4 million tons per year in the Asia Pacific. The model relies on routinely monitored data such ASTM distillation curves, paraffin-napthene- aromatic (PNA) analysis and operating conditions. We account for dehydrogenation, dehydrocyclization, isomerization and hydrocracking reactions that typically occur with petroleum feedstock. In addition, this work accounts for the coke deposited on the catalyst and product recontacting sections. This work differentiates itself from the reported studies in the literature through the following contributions: (1) detailed kinetic model that accounts for coke generation and catalyst deactivation; (2) complete implementation of a recontactor and primary product fractionation; (3) feed lumping from limited feed information; (4) detailed procedure for kinetic model calibration; (5) industrially relevant case studies that highlight the effects of changes in key process variables; and (6) application of the model to refinery-wide production planning.Ph. D.
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Pagani, Adriana Siviero. "Estudo cinetico do craqueamento catalitico de moleculas modelo de hidrocarbonetos em catalisadores de FCC." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267085.
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Orientadores: Jose Roberto Nunhez, Gustavo Paim ValençaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: O 1-octeno, 2,2,4-trimetil-pentano e n-octano foram utilizados como moléculas modelo para o estudo experimental e de modelagem do craqueamento catalítico na superfície de dois catalisadores comerciais (PETROBRAS), compostos por zeólita USY e matriz (SiO2-Al2O3) com impregnação de terras raras (CTR) e sem a impregnação de terras raras (STR), ambos desativados pelo método vapor. Os testes de craqueamento catalítico foram realizados em fase gasosa em reator tubular de leito fixo, construído em quartzo, na faixa de temperatura de 325 a 685 K para o 1-octeno, 725 a 950 K para o 2,2,4-trimetil-pentano e 815 a 975 K para o n-octano à pressão atmosférica. O catalisador STR apresentou valores de taxa de giro (s-1) maiores que os encontrados para o CTR. As energias de ativação aparente apresentaram a seguinte ordem decrescente: n-octano (STR: 180 kJ mol-1 e CTR: 192 kJ mol-1) > 2,2,4-trimetil-pentano (STR: 121 kJ mol-1 / CTR: 127 kJ mol-1) > 1-octeno (STR: 18 kJ mol-1 / CTR: 23 kJ mol-1). Os mecanismos de reações foram determinados para as três moléculas modelo através dos produtos de reação determinados experimentalmente e considerando as famílias de reações de iniciação, isomerização, transferência de hidrogênio, adsorção/dessorção e cisão-ß/oligomerização. A modelagem do craqueamento catalítico foi desenvolvida segundo a teoria da colisão, a teoria do estado de transição e as propriedades termodinâmicas das espécies envolvidas nos mecanismos. As taxas de giro da modelagem cinética apresentaram uma diferença com as taxas de giro experimentais de aproximadamente 20%.
Abstract: The 1-octene, 2,2,4-trimethylpentane and n-octane were used as model molecules in an experimental and modeling study for the catalytic cracking on the surface of commercial catalysts (PETROBRAS) that are composed of USY zeolite and matrix with rare earth impregnation (CTR) and without rare earth impregnation (STR), both deactivated by steam method. The experimental tests were carried out in the gas phase, in a fixed bed tubular reactor made of quartz in the temperature range of 325 to 685 K for the 1-octene, 725 to 950 K for the 2,2,4-trimethylpentane and 815 to 975 K for the n-octane at atmospheric pressure. The catalyst STR showed higher values of turnover rate (s-1) than the catalyst CTR. The apparent activation energies showed the following decreasing order: n-octane (STR: 180 kJ mol-1 and CTR: 192 kJ mol-1) > 2,2,4-trimethylpentane (STR: 121 kJ mol-1 / CTR: 127 kJ mol-1) > 1-octene (STR: 18 kJ mol-1 / CTR: 23 kJ mol-1). The reactions mechanisms were determined for the three model molecules with the reaction products obtained experimentally and considering the families of reactions of initiation, isomerization, hydride transfer, adsorption/desorption and ß-scission/oligomerization. The modeling of the catalytic cracking was developed according to the collision theory, the transition state theory and the thermodynamics properties of the adsorbed species involved in the mechanisms. The model turnover rates showed a difference between the experimental turnover rates near 20 %.
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
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Whitcombe, Joshua Matthew, and n/a. "Study of Catalyst Particle Emissions From a Fluidized Catalytic Cracker Unit." Griffith University. School of Environmental Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20031003.152200.
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The control of particle emissions from an oil refinery is often difficult, due to changing operational conditions and the limited range of available treatment options. Excessive particle emissions have often been attributed start up problems with Fluidized Catalytic Cracker Units (FCCU) and little information is available regarding the exact composition and nature of these excessive emissions. Due to the complex nature of a FCCU, it has in the past been difficult to identify and control emissions, without the use of expensive end of pipe technologies. An Australian Oil Refinery, concerned with their catalyst emissions, sponsored this study of FCCU particle emissions. Due to the industrial nature of the project, a holistic approach to the management of emissions was taken, instead of a detailed investigation of a single issue. By looking at the broader range of issues, practical and useful outcomes can be achieved for the refinery. Initially, detailed emissions samplings were conducted to investigate the degree of particle emissions under start up conditions. Stack emissions were collected during a standard start up, and analysed to determine the particle size distribution and metal concentration of the emitted material. Three distinct stages of emissions were discovered, initially a high concentration of larger particles, followed by a peak in the very fine particles and finally a reduction of particle emissions to a more steady or normal operational state. The variation in particle emissions was caused by operational conditions, hardware design and catalyst characteristics. Fluctuations in the gas velocity through the system altered the ability of the cyclones to collect catalyst material. Also, the low bed level allowed air bypass to occur more readily, contributing to the increased emissions levels seen during the initial stage of the start up. Reduced fluidity characteristics of the circulating catalyst also affected the diplegs operations, altering the collection efficiency of the cyclone. During the loading of catalyst into the system, abraded material was quickly lost due to its particle size, contributing to fine particle emissions levels. More importantly, thermal fracturing of catalyst particles occurred when the cold catalyst was fed into the hot regenerator. Catalyst particles split causing the generation of large amounts of fine particle material, which is easily lost from the system. This loading of catalyst directly linked to the period of high concentration of fine particles in the emissions stream. It was found that metals, and in particular iron, calcium and silicon form a thick layer on the outside of the catalyst, with large irregular shaped metal ridges, forming along the surface of the particle. These ridges reduce the fluidity of the catalyst, leading to potential disruptions in the regenerator. In addition to this, the metal rich ridges are preferentially removed via attrition, causing metal rich material to be emitted into the atmosphere. To overcome these high particle emissions rates from the FCCU the refinery should only use calcinated catalyst to reduce the influence of thermal process and particle fracture and generation. Although the calcinated catalyst can fracture when added to the system, it is far less than that obtained with uncalicinated catalyst. To further reduce the risk of particle fracture due to thermal stresses the refinery should consider reducing the temperature gradients between the hot and cold catalyst. Due to the economics involved with the regenerator, possible pre-warming of catalyst before addition into system is the preferred option. This pre-heating of catalyst should also incorporate a controlled attrition stage to help remove the build up of metals on the surface of the particles whilst allowing this material to be collected before it can be released into the atmosphere. The remove of the metal crust will also improve the fluidity of the system and reduce the chance of catalyst blockages occurring. Finally, modelling of the system has shown that control of key parameters such as particle size and gas velocity are essential to the management of air emissions. The refinery should look at adjusting start up procedures to remove fluctuations in these key parameters. Also the refinery should be careful in using correlation found in the literature to predicted operational conditions in the system as these correlations are misleading when used under industrial situations.
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Whitcombe, Joshua Matthew. "Study of Catalyst Particle Emissions From a Fluidized Catalytic Cracker Unit." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/367301.
Full textAbstract:
The control of particle emissions from an oil refinery is often difficult, due to changing operational conditions and the limited range of available treatment options. Excessive particle emissions have often been attributed start up problems with Fluidized Catalytic Cracker Units (FCCU) and little information is available regarding the exact composition and nature of these excessive emissions. Due to the complex nature of a FCCU, it has in the past been difficult to identify and control emissions, without the use of expensive end of pipe technologies. An Australian Oil Refinery, concerned with their catalyst emissions, sponsored this study of FCCU particle emissions. Due to the industrial nature of the project, a holistic approach to the management of emissions was taken, instead of a detailed investigation of a single issue. By looking at the broader range of issues, practical and useful outcomes can be achieved for the refinery. Initially, detailed emissions samplings were conducted to investigate the degree of particle emissions under start up conditions. Stack emissions were collected during a standard start up, and analysed to determine the particle size distribution and metal concentration of the emitted material. Three distinct stages of emissions were discovered, initially a high concentration of larger particles, followed by a peak in the very fine particles and finally a reduction of particle emissions to a more steady or normal operational state. The variation in particle emissions was caused by operational conditions, hardware design and catalyst characteristics. Fluctuations in the gas velocity through the system altered the ability of the cyclones to collect catalyst material. Also, the low bed level allowed air bypass to occur more readily, contributing to the increased emissions levels seen during the initial stage of the start up. Reduced fluidity characteristics of the circulating catalyst also affected the diplegs operations, altering the collection efficiency of the cyclone. During the loading of catalyst into the system, abraded material was quickly lost due to its particle size, contributing to fine particle emissions levels. More importantly, thermal fracturing of catalyst particles occurred when the cold catalyst was fed into the hot regenerator. Catalyst particles split causing the generation of large amounts of fine particle material, which is easily lost from the system. This loading of catalyst directly linked to the period of high concentration of fine particles in the emissions stream. It was found that metals, and in particular iron, calcium and silicon form a thick layer on the outside of the catalyst, with large irregular shaped metal ridges, forming along the surface of the particle. These ridges reduce the fluidity of the catalyst, leading to potential disruptions in the regenerator. In addition to this, the metal rich ridges are preferentially removed via attrition, causing metal rich material to be emitted into the atmosphere. To overcome these high particle emissions rates from the FCCU the refinery should only use calcinated catalyst to reduce the influence of thermal process and particle fracture and generation. Although the calcinated catalyst can fracture when added to the system, it is far less than that obtained with uncalicinated catalyst. To further reduce the risk of particle fracture due to thermal stresses the refinery should consider reducing the temperature gradients between the hot and cold catalyst. Due to the economics involved with the regenerator, possible pre-warming of catalyst before addition into system is the preferred option. This pre-heating of catalyst should also incorporate a controlled attrition stage to help remove the build up of metals on the surface of the particles whilst allowing this material to be collected before it can be released into the atmosphere. The remove of the metal crust will also improve the fluidity of the system and reduce the chance of catalyst blockages occurring. Finally, modelling of the system has shown that control of key parameters such as particle size and gas velocity are essential to the management of air emissions. The refinery should look at adjusting start up procedures to remove fluctuations in these key parameters. Also the refinery should be careful in using correlation found in the literature to predicted operational conditions in the system as these correlations are misleading when used under industrial situations.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environmental Engineering
Faculty of Environmental Sciences
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Khangkham, Supaporn. "Catalytic degradation of poly(methyl methacrylate) by zeolites and regeneration of used zeolites via ozonation." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/9227/1/khangkham.pdf.
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Catalytic degradation of PMMA was successfully performed at temperatures below 300°C. The use of zeolite catalyst could reduce reaction temperature in comparison with an ordinary thermal degradation process. It was found that the product distribution obtained from batch experiment depends on zeolite acid properties whereas the composition of the liquid fraction is directly related to the shape selectivity of the catalyst. A continuous fixed bed process was designed that allowed to obtain MMA monomer as main product. The increase of reaction temperature from 200 to 270°C showed a positive effect on the liquid product yield. However, at higher temperatures, the light product was further cracked into gaseous products. Significant deactivation of ZSM-5 catalyst was observed after 120 hours of operation, resulting in a decrease in liquid product yield. Regeneration of the coked ZSM-5 extrudates was achieved by oxidation with ozone at low temperatures, below 150°C. The effects of temperature, GHSV and inlet concentration of ozone on carbon removal efficiency were studied. Carbon removal with ozone started at 50°C and reached a maximum of 80% at 100°C. Higher temperatures were not beneficial due to the strong limitation of ozone diffusion which confines radical production then the regeneration process to the outer surface. In optimal conditions, ozonation almost fully restored the zeolite activity without damaging the texture and active sites of zeolite, as shown from the results of regenerated catalyst in PMMA cracking
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Muller, Michel. "Etude de reactions d'isomerisation, de cracking et d'alkylation d'hydrocarbures en presence de divers superacides." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13022.
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Kantarelis, Efthymios. "Catalytic Steam Pyrolysis of Biomass for Production of Liquid Feedstock." Doctoral thesis, KTH, Energi- och ugnsteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-142412.
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The current societal needs for fuels and chemical commodities strongly depend on fossil resources. This dependence can lead to economic instabilities, political problems and insecurity of supplies. Moreover, global warming, which is associated with the massive use of fossil resources, is a dramatic “collateral damage” that endangers the future of the planet. Biomass is the main renewable source available today that can, produce various liquid, gaseous and solid products. Due to their lignocellulosic origin are considered CO2 neutral and thus can generate CO2 credits. Biomass processing can meet to the challenge of reducing of fossil resources by producing a liquid feedstock that can lessen the “fossil dependence” and /or meet the increased demand via a rapidly emerging thermochemical technology: pyrolysis. The ultimate goal of this process is to produce liquid with improved properties that could directly be used as liquid fuel, fuel additive and/or feedstock in modern oil refineries and petrochemical complexes. However, the liquids derived from biomass thermal processing are problematic with respect to their handling and end use applications. Thus, alternative routes of advanced liquid feedstock production are needed. Heterogeneous catalysis has long served the oil refining and petrochemical industries to produce a wide range of fuels and products. The combination of biomass pyrolysis and heterogeneous catalysis (by bringing in contact the produced vapours/liquids with suitable catalysts) is a very promising route. In this dissertation, the exploitation of biomass to produce of liquid feedstock via pyrolysis over a multifunctional catalyst and in a steam atmosphere is investigated. Steam pyrolysis in a fixed bed reactor demonstrated that steam can be considered a reactive agent even at lower temperatures affecting the yields and the composition of all the products. The devolatilisation accelerates and the amount of final volatile matter in the char. Fast pyrolysis in the presence of steam results in improved and controlled thermal decomposition of the biomass; higher liquid yields and slightly deoxygenated liquid products are also obtained. Steam pyrolysis over a bi-metallic Ni-V catalyst can produce liquids of improved quality (lower O content) and also provide routes for selective deoxygenation. However, a decrease in liquid yield was observed. The combination of metal and acid catalysts (Ni-V/HZSM5) shows enhanced deoxygenation activity and increased H preservation in the produced liquid. The final O content in the liquid was 12.83wt% at a zeolite (HZSM5) loading of~75wt%; however, the yield of the obtained liquid was substantially decreased. Moreover, increased coke formation on the catalyst was observed at highest zeolite rate. The increased catalyst space time (τ) results in a lower liquid yield with reduced oxygen (7.79 wt% at τ =2h) and increased aromatic content. The coke deposited per unit mass of catalyst is lower for longer catalyst space times, while the char yield seems to be unaffected. The evaluation of the stability of the hybrid catalyst showed no significant structural defects and activity loss when the catalyst was regenerated at a low temperature (550οC).Det nuvarande samhällets behov av bränslen och kemiska produkter är starkt knutet till fossila resurser. Detta beroende kan leda till ekonomisk instabilititet, politiska svårigheter och osäker leveranssäkerhet. Dessutom riskeras allvarliga skador i framtiden på grund av global uppvärmning, vilket är relaterat till det ökande och massiva användandet av fossila bränslen. Biomassa är en förnybar resurs som är tillgänglig idag, möjlig att utnyttja för produktion av diverse flytande, gasformiga och fasta produkter. Dessa produkter, beroende på biogeniskt ursprung, betraktas som koldioxidneutrala och kan därför generera koldioxidkrediter. Processande av biomassa kan möta utmaningen av minskad fossilbränsleanvändning, genom produktion av flytande råvara som kan reducera beroendet och/eller möta ökad efterfrågan, via en snabbt expanderande termokemisk teknik - pyrolys. Det slutgiltiga målet med en sådan process är att producera en flytande produkt med förbättrade egenskaper som direkt skulle kunna användas som flytande bränslen, bränsleadditiv och/eller som råmaterial i moderna oljeraffinaderier och petrokemiska komplex. Vätskor som utvinns från termiska processer är problematiska med avseende på hantering och slutanvändningen i olika applikationer, därmed behövs olika spår för produktion av avancerade flytande råvaror. Heterogena katalysen har länge tjänat raffinaderi- och petrokemisk industri, som producerar ett brett utbud av bränslen och produkter, lämpliga för säker användning. Kombinationen av biomassapyrolys och heterogen katalys (genom att bringa pyrolysångorna i kontakt med en lämplig katalysator) är ett väldigt lovande spår. I denna avhandling undersöks användningen av biomassa för produktion av flytande råvara, via pyrolys över en flerfunktionel katalysator i ångatmosfär. Ångpyrolys i en fastbäddsreaktor visade att ånga kan betraktas som ett reaktivt medium, även vid låga temperaturer, som påverkar utbyten och sammansättning av alla produkter. Avgasningen sker snabbare och den slutliga flykthalten i kolresterna blir lägren vid användning av ånga. Snabbpyrolys i ångatmosfär resulterar i förbättrad och mer kontrollerad termisk nedbrytning av biomassa, vilket ger ett högre vätskeutbyte och en något deoxygenerad flytande produkten. ångpyrolys i kombination med bimetalliska NiV-katalysatorer, ger upphov till en flytande råvara med förbättrad kvalitet och selektiv deoxygenering. Dock med ett minskande utbyte som följd. Kombinationen av metall och en sur katalysator (Ni-V/HZSM5) visade förstärkt deoxygenering med bibehållen vätehalt i den flytande produkten. Den slutliga syrehalten i vätskan var 12.83 vikt% vid en zeolithalt (HZSM5) på 75 vikt%, dock med ett kraftigt minskande vätskeutbyte. Dessutom noterades ökad koksbildning på katalysatormaterialet med den högsta zeolithalten. Ökad rymd-tid för katalysatorn (τ) ger ett lägre vätskeutbyte med reducerad syrehalt (7.79 vikt% vid τ=2h) och ökad aromathalt. Koksbildning på ytan, per massenhet katalysatormaterial, minskade vid längre rymd-tider medan utbytet av kolrester förblev opåverkat. Undersökningen av stabiliteten hos hybridkatalysatorn visade inga strukturella defekter och ingen signifikant minskad aktivitet efter regenerering vid låg temperatur (550οC).
Οι σύγχρονες ανάγκες της κοινωνίας για παραγωγή υγρών καυσίμων και χημικών προϊόντων εξαρτώνται από τους ορυκτούς πόρους. Αυτή η εξάρτηση μπορεί να οδηγήσει σε οικονομικά προβλήματα, πολιτκή αστάθεια, όπως επίσης και αβεβαιότητα στις προμήθειες της ενεργειακής εφοδιαστικής αλυσίδας. Επιπροσθέτως, μια δραματική «παράπλευρη απώλεια» η οποία θέτει σε κίνδυνο το μέλλον του πλανήτη είναι η υπερθέρμανσή του, η οποία έχει συσχετισθεί με την εκτεταμένη χρήση ορυκτών πόρων. Σήμερα, η βιομάζα είναι η μόνη ανανεώσιμη πηγή από την οποία μπορούν να παραχθούν υγρά, αέρια και στερεά προϊόντα, που λόγω της λιγνοκυταρρινικής τους προελεύσεως, η συνεισφορά τους στις εκομπές CO2 θεώρειται μηδενική. Η θερμοχημική επεξεργασία της βιομάζας συνεισφέρει στον περιορισμό της χρήσης ορυκτών πόρων, με την παραγωγή υγρών προϊόντων, τα οποία μπορούν να μειώσουν την εξάρτηση ή /και την αυξημένη ζήτηση μέσω μιας ταχέως αναπτυσόμενης τεχνολογίας, της πυρόλυσης. Στόχος της διεργασίας είναι η παραγωγή υγρών προϊόντων με ιδιότητες, που επιτρέπουν την απευθείας χρήση τους ως υγρά καύσιμα ή ως πρώτη ύλη, για την παραγώγη χημικών προϊόντων σε συγχρονες μονάδες διύλισης πετρελαίου και σε πετροχημικά συγκτροτήματα. Εν τούτοις, τα υγρά προϊόντα της θερμικής διάσπασης (πυρόλυση) είναι προβληματικά στη διαχείρηση και στις τελικές τους εφαρμογές, λόγω της σύστασής τους. Ως εκ τούτου, απαιτούνται νέες τεχνικές για παραγωγή προηγμένων υγρών προοϊόντων. Η ετερογενής κατάλυση έχει επιτυχώς εφαρμοσθεί στην πετρελαϊκή και χημική βιομηχανία, παράγοντας ένα μεγάλο εύρος προϊόντων. Ο συνδυασμός της με την πυρόλυση (φέρνοντας σε επαφη τα υγρά/ατμούς με κατάλληλο καταλύτη) αποτελεί μια πολλά υποσχόμενη ενναλακτική. Στην παρούσα διατριβή μελετάται η αξιοποίηση βιομάζας για παραγωγή υγρών προϊόντων μέσω καταλυτικής πυρόλυσης, με χρήση πολυλειτουρικού καταλύτη (multi-functional catalyst) υπό την παρουσία ατμού. Η χρήση ατμου κατά τη διαρκειά πυρόλυσης βιομαζας σε αντιδραστήρα σταθερής κλίνης, μεταβάλει τη σύσταση των επιμέρους προϊόντων. Η παρουσία ατμού έχει ως αποτέλεσμα την ταχύτερη αποπτητικοποίηση του υλικού, ενώ παράλληλα η περιεκτικότητα του υπολειπόμενου εξανθρακώματος σε πτητικά είναι μικρότερη. Τα πειραματικά αποτελέσματα ταχείας πυρόλυσης σε αντιδραστήρα ρευστοστερεάς κλίνης δείχνουν ό,τι η χρήση ατμού βελτιώνει την θερμική διάσπαση της βιομαζας, αυξάνοντας την απόδοση σε υγρά προϊοντά, ενώ παράλληλα βοηθάει στην αποξυγόνωσή τους. Ο συνδυασμός της πυρόλυσης υπό την παρουσία ατμού και διμεταλλικού καταλύτη νικελίου–βαναδίου μπορεί να βελτιώσει την ποιότητα των παραγόμενων υγρών (αποξυγόνωση) με παραλλήλη μείωση της απόδοσής τους, ενώ μπορεί να παράγει προϊόντα εκλεκτικής αποξυγόνωσης. Συνδυασμός μεταλλικών και ζεολιθικών καταλυτών (Ni-V/HZSM5) εμφανίζει βελτιωμένη δραστικότητα στις αντιδράσεις αποξυγόνωσης, με παράλληλη συγκράτηση υδρογόνου (Η) στα υγρά προϊόντα. Η τελική περιεκτικότητα των υγρών προϊόντων σε οξυγόνου (Ο) μετά από 90 min αντίδρασης είναι 12.83 wt%, με περιεκτικότητα ζεόλιθου (ΗZSΜ5) ~75 wt% στον καταλύτη. Ωστόσο, η αυξηση της περεικτικότητας σε ζεόλιθο έχει ως αποτέλεσμα την αύξηση των επικαθήσεων άνθρακα επάνω στον κατάλυτη, καθώς και την σημαντική μειώση της απόδοσης των υγρών προϊόντων (24.35wt% επι ξηρής βιομάζας). Η αύξηση του χώρου χρόνου του καταλύτη (τ) έχει ως αποτέλεσμα: τη μείωση των υγρών προϊόντων, τη μείωση του περιεχόμενου Ο στα υγρά προϊόντα (7.79 wt% at τ =2h), την αύξηση των αρωματικών υδρογονανθράκων και τη μείωση του επικαθήμενου κωκ ανά μονάδα μάζας καταλύτη. Η απόδοση του εξανθρακώματος παρέμεινε πρακτικά αμετάβλητη. Η αναγέννηση του υβριδικού καταλύτη σε χαμηλές θερμοκρασιές (550οC) δεν επέφερε σημαντικές δομικές αλλαγές και απώλεια δραστικότητας.
QC 20140306
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Schallmoser, Stefan [Verfasser], Johannes A. [Akademischer Betreuer] Lercher, and Klaus [Akademischer Betreuer] Köhler. "Insight into Catalytic Cracking of Hydrocarbons over MFI type Zeolites / Stefan Schallmoser. Gutachter: Johannes A. Lercher ; Klaus Köhler. Betreuer: Johannes A. Lercher." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1064976352/34.
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Nqakala, Loyiso Clemence. "Hydrothermal synthesis of hierarchical ZSM-5 with different Si/Al ratio and their evaluation as catalysts in the catalytic cracking of hexane." University of Western Cape, 2021. http://hdl.handle.net/11394/8316.
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>Magister Scientiae - MScEthylene and propylene are greatly used for their importance as feedstocks for producing useful materials. Due to rise in prices and the demand of ethylene and propylene, the need to increase the selective production of these light olefins is necessary. To achieve this, zeolites, specifically ZSM-5 has been used to investigate catalytic cracking of several types of hydrocarbons for the production of these light olefins. This study focuses on developing hierarchical macro and/or mesoporous ZSM-5 zeolites with variable Si/Al ratios. The synthesized materials were then evaluated on their performance via catalytic cracking of hexane, dodecane and tyre derived oil [TDO] to produce light olefins, particularly ethylene and propylene.
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Smith, Bradley Joseph. "Steam-Assisted Catalysis of n-Dodecane as a Jet Fuel Analogue in a Flow Reactor System for Hypersonic Thermal Management." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1577978953025703.
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Cois, Giulia. "Aggiornamento e miglioramento della matrice di simulazione delle rese di un impianto di cracking catalitico a letto fluidizzato." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
Il processo FCC, Fluid Catalytic Cracking, è un processo catalitico che per effetto della temperatura ed in presenza di un catalizzatore acido, effettua una rottura delle molecole pesanti degli idrocarburi, dando origine a prodotti leggeri, principalmente benzine ad alto numero di ottano.
La matrice di simulazione dell’impianto di cracking catalitico a letto fluidizzato è un modello statistico-matematico necessario per prevedere le rese dei prodotti dell’impianto in funzione delle caratteristiche della carica, per ottimizzare la carica stessa e massimizzare la conversione della reazione di cracking in termini economici.
Obiettivo del presente lavoro di tesi è stato l’aggiornamento della matrice con una popolazione di dati significativa, al fine di simulare il processo e la sua modifica, in modo da migliorare la capacità predittiva.
Il lavoro di tesi è così strutturato.
Dopo il presente Capitolo 1 avente carattere introduttivo, nel Capitolo 2 si descrive, in termini generali, il processo di cracking catalitico a letto fluidizzato.
Nel Capitolo 3 è presentata l’implementazione del processo di cracking catalitico a letto fluidizzato all’interno della raffineria Sarlux, con la descrizione degli impianti e delle variabili operative.
Nel Capitolo 4 si descrivono, in termini generali, le nozioni statistiche e matematiche alla base del modello matematico utilizzato per prevedere le rese dell’impianto FCC.
Nel Capitolo 5 si discutono le azioni eseguite per aggiornare il modello di simulazione delle rese dell’impianto di cracking.
Infine il Capitolo 6 contiene le considerazioni conclusive degli studi effettuati.
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Ribeiro, Pleycienne Trajano. "Modelagem e controle de unidades de craqueamento catalitico - FCC." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266266.
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Orientador: Rubens Maciel FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Por representar um importante processo de conversão da indústria petroquímica, o craqueamento catalítico é um dos processos de conversão mais estudados. Nele, moléculas de alto peso molecular são quebradas em moléculas com menor peso molecular, obtendo-se assim produtos economicamente mais desejáveis. Os estudos do processo, de sua modelagem matemática e dos seus sistemas de controle, podem garantir o conhecimento necessário para alcançar condições operacionais ótimas que levem à máxima conversão da carga. Neste contexto, este trabalho teve como objetivos: a pesquisa e utilização de uma modelagem matemática para o conversor FCC (Fluid Catalytic Cracking); o estudo do processo sob influência de um controlador PID clássico, muito utilizado em refinarias; a estruturação de uma rede neural artificial (RNA) e o seu posterior uso como modelo interno de um controlador avançado tipo preditivo desenvolvido a partir dos estudos feitos no processo de craqueamento catalítico. Em paralelo, foi cirada uma ferramenta de simulação que possibilitou o meio mais amigável e prático para realização de todas as simulações necessárias para o desenvolvimento do presente trabalho. O FCCGUI (Fluid Catalytic Cracking Graphical User Interface), nome dado ao simulador, proporciona a escolha de parâmetros de simulação, diferentes estruturas de controle (PID, DMC e MPC - baseado em redes neurais), a visualização de diferentes variáveis manipuladas, controladas e sinais de válvulas e facilidades para perturbar o sistema. Através das simulações foi possível acompanhar o comportamento das variáveis de processo em diferentes condições testadas, realizar a estruturação da rede neural e obter as respostas das variáveis controladas para os dois tipos de controladores estudados. Os resultados obtidos foram bastante satisfatórios, visto que a modelagem matemática escolhida representa bem o sistema e o controlador MPC-Neural desenvolvido se mostrou eficiente, por conseguir manter o processo estável e próximo ao set point, mesmo após a aplicação de perturbações no processo
Abstract: Catalytic cracking is one of the most studied conversion processes due its importance in the petrochemical industry. In this process high weight molecules are broken into lighter ones, yielding more economically valuable products. The study about the process, its mathematical modeling, and its control systems may guarantee the necessary knowledge needed to reach optimal operational conditions which lead to maximum load conversion. In this context, the present work thesis has as main objectives the research and use of a mathematical modeling for a FCC (Fluid Catalytic Cracking) conversion unit, the study of the system under PID control loop widely used in refineries, structuring of an artificial neural network (ANN) with its use as an internal model of a predictive control system developed for catalytic cracking. Parallel to this, it was developed a computational tool which in a friendly and practical way made possible to carry out simulations needed to accomplish this work. FCCGUI (Fluid Catalytic Cracking Graphical User Interface), name given to this simulator, allows to choose simulation parameters, different control systems (PID, DMC, and MPC-ANN Based), graphical visualization of many different variables, such as manipulated and controlled variables plus valve signals, also it allows for and easy means for disturbing the system while the simulation continues. Through the simulations it was possible to follow the behavior of many process variables under different tested operational conditions, to structure the neural network, and to obtain controlled variables responses for both types of control systems studied. The obtained results were quite satisfactory since the chosen mathematical modeling represents well the system and the developed MPC-ANN controller showed to be efficient to maintain the process stable and close to the set points even after the introduction of disturbances in the process. Taking all these into account, compared to PID controller, MPC-ANN showed to be less oscillatory and to be more effective
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
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Issa, Hussein. "Toolbox of post-synthetic mordenite modification strategies : Impact on textural, acidic, and catalytic properties." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2268.
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Les zéolithes sont des catalyseurs hétérogènes extrêmement utiles et trouvent des applications industrielles répandues. Cependant, leur système microporeux étendu conduit à des facteurs d'efficacité plutôt faibles et favorise le développement de réactions secondaires pouvant réduire considérablement la sélectivité et la stabilité catalytique. La hiérarchisation des zéolithes a été proposée comme stratégie permettant de réduire efficacement la longueur du trajet de diffusion, permettant ainsi d'augmenter le facteur d'efficacité en catalyse. Parmi la multitude de stratégies de hiérarchisation divulguées, l'impact réel des modifications structurelles et chimiques sur les paramètres clés catalytiques est souvent négligé. Le but de cette contribution est donc de faire la lumière sur la qualité effective de la hiérarchisation des zéolites à travers l'étude rationnelle de la dépendance structure / propriété catalytique. Notre étude s'est concentrée sur la mordénite, cette zéolite revêtant une importance particulière en raison de sa forte acidité et de son système de canaux monodimensionnel, ce qui explique pourquoi la mordénite est largement utilisée industriellement dans divers procédés, notamment l'alkylation d'aromatiques, les isomérisations d'alcanes, et les déshydratations d'alcools. Des stratégies de hiérarchisation post-synthétiques sur les mordénites riches et pauvres en aluminium ont été développés sur la base de traitements de basique assisté par CTAB, pyridine à différentes températures (en chauffage conventionnel et par micro-ondes), et par attaque chimique HF en milieu aqueux et organique. Une étude systématique de plus de 50 mordénites post-synthétiquement modifiées a été menée, ce qui nous a permis d'évaluer l'impact de chacune des stratégies de hiérarchisation sur les propriétés texturales, morphologiques, chimiques et catalytiques. Des corrélations majeures entre les caractéristiques structurelles et l'activité catalytique, la sélectivité et la stabilité dans le craquage du n-hexane et dismutation du toluène ont été déduites. Une feuille de route sur la qualité de chaque stratégie de hiérarchisation a ainsi été élaboréeZeolites are extremely useful heterogeneous catalysts and find widespread industrial applications. Yet, their extended microporous system leads to rather low efficiency factors and favors the development of secondary reactions that can substantially reduce catalytic selectivity and stability. Hierarchization of zeolites has been proposed as strategy for efficiently reducing the diffusion path length, hence allowing to increase the efficiency factor in catalysis. Among the plethora of disclosed hierarchization strategies, the real impact of the structural and chemical modifications on the catalytic key parameters is oftentimes neglected. The aim of this contribution is thus to shed light on the effective quality of zeolite hierarchization through the rational study of structure/catalytic property dependency. Our study focused on mordenite, as this zeolite is of particular importance due to its strong acidity and monodimensional channel system, which explains why mordenite is industrially extensively employed in a variety of processes including alkylations, isomerizations, dehydrations and aminations. A toolbox of post-synthetic hierarchization strategies on aluminium rich and poor mordenites have been developed based on basic treatments assisted by CTAB and pyridine at various temperatures (in conventional and microwave heating) and acid HF etching in aqueous and organic medium. A systematic study of over 50 post-synthetically modified mordenites was conducted, which allowed us to assess the impact of each of the hierarchization strategy on textural, morphological, chemical and catalytic properties. Major correlations between structural features and catalytic activity, selectivity and stability in n-hexane cracking and toluene disproportionation were deduced. A roadmap on the quality of each hierarchization strategy was thus developed
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Pelissari, Daniel Cícero 1989. "Estudo da influência dos bicos injetores sobre o escoamento gás-sólido e as reações em um riser de FCC via CFD." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266017.
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Orientador: Milton MoriDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: A aplicação de fluidodinâmica computacional (CFD) em estudos de otimização e projeto de novos equipamentos de processos industriais vem aumentando significativamente, uma vez que apresenta custo reduzido e possibilidade de avaliar equipamentos complexos e de extremas condições de operação. Dentre os processos mais estudados via CFD está o processo de craqueamento catalítico fluidizado (FCC), onde as frações pesadas do petróleo de baixo valor são convertidas em produtos de maior valor agregado, sendo uma das aplicações de fluidização gás-sólido mais importante na indústria de petróleo. O presente trabalho avaliou especificamente a zona de injeção do FCC, na qual a matéria-prima, alimentada por bicos injetores, se mistura a sólidos quentes (catalisador) e a vapor de fluidização. A performance desses dispersores de carga para garantir uma boa distribuição das gotículas de gasóleo com o catalisador é a chave para melhorar a eficiência do riser de FCC. Desta forma, o principal objetivo deste trabalho foi avaliar o efeito de diferentes designs, ângulos (30°, 45° e 60°) e configurações dos injetores sobre o escoamento gás-sólido e o desempenho do riser. Para tal, simulou-se um escoamento gás-sólido reativo tridimensional baseado em uma abordagem Eulerian-Eulerian. Nas simulações foram utilizados o modelo cinético de 12-lumps de Wu et al. (2009), modelo de turbulência k-? e modelo de arraste de Gidaspow. Foi observado que o design, o ângulo e a configuração dos bicos injetores exercem uma forte influência sobre a fluidodinâmica e a performance do riser, sendo o ângulo a variável que apresentou maior influência. Pôde-se observar que o design de bico tipo multi-orifícios (Caso 3) foi o que apresentou os melhores resultados, sendo a partir deste avaliados os ângulos, onde notou-se que o aumento do ângulo de 30° para 60° melhorou a mistura entre as fases e o rendimento. A análise dos arranjos foi realizada utilizando o design de bico do Caso 3 e o ângulo de 45°, e observou-se que o arranjo com bicos intercalados (Arranjo 2) apresentou uma mistura mais homogênea entre as fases e, consequentemente, uma melhor conversão e rendimento de produtos desejados. Em geral, os resultados obtidos no presente trabalho salientam a importância da utilização de geometrias mais detalhadas para os bicos, uma vez que influenciam a mistura entre as fases, a qual afeta o desempenho do riser
Abstract: The Computational Fluid Dynamic (CFD) application in industrial process optimization and new equipments design studies has increased significantly, once it presents low cost and the possibility of evaluating complex and extreme operating conditions equipments . Among the most widely studied processes via CFD is the fluidized catalytic cracking process (FCC), where the oil heavy fractions of low-value are converted into higher value-added products and which is one of the most important gas-solid fluidization applications in the oil industry . The present study specifically evaluated the FCC injection zone, in which the feedstock fed by nozzles, is mixed with hot solids (catalyst) and fluidization steam. The nozzles performance to guarantee a good gas oil droplets distribution with the catalyst is the key to improve the efficiency of FCC riser. Thus, the study main objective was to evaluate the different nozzles designs, angles (30 °, 45 ° and 60 °) and arrangements effect on the gas-solid flow and the riser performance. For this purpose, it was simulated a three-dimensional reactive gas-solid flow based on an Eulerian-Eulerian approach. In the simulations it was used the 12 lumps kinetic model by Wu et al. (2009), turbulence model k- ? and drag model Gidaspow. It was observed that the nozzle design, angle and configuration have a strong influence on fluid dynamics and on the riser performance, and the angle was the variable with the greatest influence. It can be observed that the nozzle design of multi-orifice type (Case 3) showed the best results, and that¿s why it was used to evaluate the angle, in which was noted that the angle increase of 30 ° to 60 ° improved phases mixing and the yield. The arrangement analysis was performed using Case 3 nozzle design and the design angle of 45 °, and it was observed that the arrangement with intercalated nozzles (Arrangement 2) showed a more homogeneous phases mixture and therefore a better conversion and desired product yield. In general, the results obtained in this work highlighted the importance of using more detailed geometries for the nozzles, since they influence the mixing of the phases, which affects the riser performance
Mestrado
Engenharia Química
Mestre em Engenharia Química
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COSTA, Potí Oliveira Cortêz. "Elaboração de um reator contínuo para síntese de biocombustível: avaliação experimental com sebo animal." Universidade Federal de Campina Grande, 2015. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/704.
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Em busca de alternativas para o aproveitamento de resíduos do abate animal foi estudado um protótipo de reator contínuo de custo-benefício acessível para uso popular na agroindustrial local, com fins de produzir biocombustível líquido. Bem como, avaliação experimental por meio deste aproveitamento com o sebo, adquirido nos abatedouros públicos e caseiros de Catolé do Rocha-PB, utilizando dois tipos de métodos, a saber: hidroesterificação e craqueamento térmico catalítico. O sistema foi construído em escala de laboratório, composto por materiais metálicos de aço inox e algumas conexões de silicone. O sistema foi composto por reator, trocador de calor e uma bomba periférica comercial de 1/4CV. O aquecimento foi efetuado por chama a gás, o fluxo, a temperatura e pressão foram monitoradas. O reator foi manufaturado resultando em um volume de 687,22 mL. A avaliação experimental do sistema proposto foi realizada introduzindo gordura animal, a qual foi extraída do sebo por duas técnicas, chapa elétrica e autoclave, buscando investigar o melhor rendimento. A autoclave foi mais significativa (75,7%). Posteriormente, a síntese do biocombustível com o método da hidroesterificação adotando o referido sistema, apresentou não conformidade operacional na conexão da saída do reator, visto que estas foram rompidas, devido à formação de vapor internamente, ocasionando retorno da mistura aquecida para a conexão com a bomba periférica. Esperava-se atingir temperatura de 260 ºC e pressão de 3bar, mas não foram atingidas. A segunda tentativa foi realizada buscando se atingir 200 ºC a 2bar, porém aos 157 ºC houve nova formação de refluxo. Diante deste fato, o sistema foi modificado, entre o reator e o trocador de calor a fim de se realizar um craqueamento termocatalítico, utilizando dois tipos de catalisadores independentemente, o carbonato de cálcio e a ferrita de níquel. Adotou-se a razão de 1:10 de catalisador/gordura injetados no sistema, pressão ambiente e temperatura acima de 600 ºC. Este método revelou bom funcionamento para o sistema idealizado, mas, ainda necessita ser aprimorado, em virtude do rendimento do bio-óleo ter sido inferior ao citado em literatura. Comparando a síntese entre os catalisadores o bio-óleo de carbonato de cálcio obteve melhor rendimento (49,51%), menor índice de acidez (1,45 mgKOH/g) porém o perfil térmico sugeriu maior presença de ácidos graxos combinados, moléculas de diacilglicerídeos e triacilglicerídeos. Já com ferrita de vii níquel teve menor rendimento 32,22%, maior índice acidez (5,36 mgKOH/g) e perfil térmico característico de apenas uma decomposição térmica sugerindo uma melhor ação catalítica. Ambos os bio-óleos apresentaram índice de acidez acima das normas da ANP.
In search of alternatives to recovery waste to animals slaughter, was studied a prototype of affordable continuous reactor for public use and local agribusiness, for purposes of producing liquid biofuels. As well, through the experimental evaluation of tallow use, acquired in public and homemade slaughterhouses Catolé Rocha-PB, using two types of methods, namely: hidroesterification and catalytic thermal cracking. The system was built on a laboratory scale, composed of metallic materials of stainless steel and some silicone connections. The system is composed of reactor, heat exchanger and pumps a commercial peripheral 1/4CV. Heating was affected by flame gas, and both flow with temperature and pressure were monitored. The reactor was manufactured resulting in a volume of 687.22 mL. The experimental evaluation of the system was carried out by introducing animal fat, which was extracted from tallow by two techniques, plates and autoclave techniques in order to investigate the best performance. The autoclave was more significant (75.7%). Thereafter, the biofuels synthesis was performed in the system, initially with the method of hidroesterification, in which one cannot observe operating line of the system, the reactor outlet connection, since these were broken due to formation of steam internally, causing returning the mixture heated for connecting to peripheral pump. Was expected reach 260 °C temperature and 3bar pressure, without success. A second attempt was carried out in order to achieve 2bar to 200 ºC, but at 157 ºC was new line of reflux. Given this fact, the system was modified between the reactor and the heat exchanger in order to hold a thermo catalytic cracking using two types of catalysts, independently, calcium carbonate and nickel ferrite. Adopted the ratio of 1:10 catalyst/fat injected into the system, ambient pressure and temperature above 600 °C. This method showed good run for the idealized system, but still needs to be improved since the yield of bio-oil was lower than that cited in the literature. Comparing the synthesis of the catalysts as calcium carbonate bio-oil obtained better yield (49.51%), acidity index (1.45 mgKOH/g), however the thermal profile suggested greater presence of fatty acids combined, diacilglicerídeos and triacilgerídeos molecules. Already with nickel ferrite had lower yield (32.22%), higher acidity index (5.36 mgKOH /g) and ix characteristic thermal profile of just one thermal decomposition suggesting a better catalytic action. Both bio-oils had acidity index above the standard of the ANP.
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Cuadros, Bohórquez José Fernando. "Avaliação e aplicação dos resultados da curva PEV estendida em sistemas de processamento e refino de frações pesadas de petroleo." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266453.
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Orientador: Rubens Maciel FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A extração de petróleo no Brasil produz, em grande parte, petróleos pesados. Este tipo de óleo é de difícil processamento e gera grande quantidade de resíduos provenientes das torres de destilação atmosférica e de vácuo. É necessário fracionar esse tipo de petróleo pesado, com a finalidade de incrementar a produção de frações leves, principalmente o Diesel. A caracterização do petróleo é feita mediante as curvas PEV (Ponto de Ebulição Verdadeiro), através das normas padronizadas ASTM (American Society fot Testing and Materials); porém, a curva de destilação só pode ser obtida mediante as normas ASTM até 565ºC. Uma extensão acima dessa temperatura limite, 565ºC, foi desenvolvida pelo grupo de pesquisa do Laboratório de Desenvolvimento de Processos de Separação (LDPS) e do Laboratório de Otimização, Projeto e Controle Avançado (LOPCA), da Faculdade de Engenharia Química da Universidade Estadual de Campinas (FEQ/ UNICAMP), como apresentado em diversos trabalhos prévios (SBAITE, 2005). A metodologia desta extensão envolve o processo de Destilação Molecular, tornando possível a caracterização de frações pesadas de petróleo acima de 565ºC. A caracterização feita com a extensão da curva PEV (nova curva PEV ou DESTMOL) foi usada nesta dissertação que fez uso do simulador de processos Hysys.Plant®, mediante a geração de pseudocomponentes, para fazer a caracterização da alimentação do sistema no processo de refino. Nesta dissertação, foi desenvolvida uma metodologia de simulação para avaliar as curvas PEV estendidas no esquema de separação após o reator de FCC (Fluid Catalytic Cracking). Nesta unidade, são obtidos diferentes produtos: GLP (Gás Liquefeito de Petróleo), gasolina e diesel. O esquema de separação e um processo complexo, incluindo diferentes correntes de reciclo. Os resultados das simulações de dois tipos de resíduos de petróleo foram comparados com dados industriais, obtendo-se bons resultados. Deste trabalho, foi possível concluir que a avaliação das curvas PEV no sistema de separação após o FCC, depende das condições de projeto e de operação desta unidade, uma vez que para valores da curva PEV na alimentação acima de 550ºC, não ocorre a vaporização de alimentações com óleos mais leves, afetando significativamente a operação da unidade. Depois de fazer comparações entre os dados industriais e os dados da simulação, pode-se concluir que a avaliação deste tipo de análise (Curva PEV estendida) deveria ser feita em outro tipo de unidade, por exemplo o riser de FCC, pois este tem a capacidade de processar frações pesadas de petróleo, que é o que esta sendo representado mediante a curva PEV estendida, em frações mais leves como: gases combustíveis, GLP e nafta de craqueamento, obtidas após sua separação na unidade de fracionamento e recuperação de produtos.
Abstract: The oil extraction in Brazil is predominantly of heavy oil. This type of oil is difficult to process and it produces great quantity of residues from atmospheric and vacuum columns. It is necessary to upgrade such kind of residues in order to increase productivity of light fractions, mainly diesel. Oil characterization is made with the aid of the True Boiling Point (TBP) curve through ASTM standard test methods; however, it is possible to have this curve only until 565 ºC. An extension beyond this temperature limit was developed by this research group and it is presented in previous works in the literature, (SBAITE, 2005). For such purpose, molecular distillation process was used, which uses high vacuum as separating agent. In this sense, extension of the True Boiling Point (TBP) curve was obtained using the molecular distillation process, making possible the characterization of the heavy oil fractions of TBP higher than 565ºC. The characterization made with the extension of the TBP was used in this work in the process simulator Hysys.Plant® by the generation of pseudocomponents for characterizing the systems feeding distillation columns in the refining process. In this work, it was developed a simulation methodology in order to evaluate all the separation sequencing after the FCC (Fluid Catalytic Cracking) reactor, in order to produce different products, like (LPG), gasoline and diesel. A complex configuration characterizes this step of the refining process, including several recycle streams. The simulation results of two types of petroleum residues, Alpha 565C+ and Gamma 545C+ were compared with industrial data, yielding, very good match. From this work, it was possible to conclude that the evaluation of the TBP curves in the FCC separation steps depends on the design conditions of this unit, considering that feed at fractionation temperature above 550 ºC remains in liquid state affecting significantly the fractionator tower operation. These results are new in the open literature. After the comparisons between industrial and simulation results, can be concluded that the evaluation of this type heavy oil analysis should be performed in another unit capable to convert these products, called heavy gasoil in noble products, which can be used in the downstream FCC. This conversion process can be performed in the FCC riser.
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
50
Heuchel, Moritz [Verfasser], and Yvonne [Akademischer Betreuer] Traa. "Co-catalytic cracking of n-decane and 2-ethylphenol as model hydrocarbons for fossil- and bio-based feeds in FCC over zeolite catalysts / Moritz Heuchel ; Betreuer: Yvonne Traa." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1156902037/34.
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