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Investigation of Hybrid Steam/Solvent Injection to Improve the Efficiency of the SAGD ProcessArdali, Mojtaba 03 October 2013 (has links)
Steam assisted gravity drainage (SAGD) has been demonstrated as a proven technology to unlock heavy oil and bitumen in Canadian reservoirs. Given the large energy requirements and volumes of emitted greenhouse gases from SAGD processes, there is a strong motivation to develop enhanced oil recovery processes with lower energy and emission intensities.
In this study, the addition of solvents to steam has been examined to reduce the energy intensity of the SAGD process. Higher oil recovery, accelerated oil production rate, reduced steam-to-oil ratio, and more favorable economics are expected from the addition of suitable hydrocarbon additives to steam.
A systematic approach was used to develop an effective hybrid steam/solvent injection to improve the SAGD process. Initially, an extensive parametric simulation study was carried out to find the suitable hydrocarbon additives and injection strategies. Simulation studies aim to narrow down hybrid steam/solvent processes, design suitable solvent type and concentration, and explain the mechanism of solvent addition to steam. In the experimental phase, the most promising solvents (n-hexane and n-heptane) were used with different injection strategies. Steam and hydrocarbon additives were injected in continuous or alternating schemes. The results of the integrated experimental and simulation study were used to better understand the mechanism of hybrid steam/solvent processes.
Experimental and simulation results show that solvent co-injection with steam leads to a process with higher oil production, better oil recovery, and less energy intensity with more favorable economy. Solvent choice for hybrid steam/solvent injection is not solely dependent on the mobility improvement capability of the solvents but also reservoir properties and operational conditions such as operating pressure and injection strategy.
Pure heated solvent injection requires significant quantities. A vaporized solvent chamber is not sustainable due to low latent heat of the solvents. Alternating steam and solvent injection provides heat for the solvent cycles and increases oil recovery. Co-injection of small volumes (5-15% by volume) of suitable solvents at the early times of the SAGD operation considerably improves the economics of the SAGD process.
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Effect of energy dissipation rate on bitumen droplet sizeMussbacher, Scott L. January 2009 (has links)
Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Sept. 1, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering, Department of Chemical and Materials Engineering, University of Alberta." Includes bibliographical references.
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Exploring transgender spirituality within a retreat setting: Theological Action ResearchWeekley, David 19 May 2016 (has links)
This project explores how a retreat ministry grounded in Theological Action Research
(TAR) may help ameliorate the harmful effects of negative religious experiences among
transgender persons. As a method of practical theology, TAR is interactive and participatory; in
this study, TAR fostered agency and ownership among retreat participants. The study identifies
larger implications of employing TAR to inform the practice of ministry, particularly among
marginalized communities. Data and feedback from retreatants indicate that a retreat created
through TAR and drawing upon spiritual autobiography, is a helpful model and method for
ministry with transgender and gender non-conforming people seeking spiritual companionship
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Modelling of gasification of poultry litterFont Palma, Carolina January 2012 (has links)
The poultry industry in Europe is vast and proper waste management is required in order to comply with environmental regulations. As a result, poultry litter represents a potential fuel candidate for thermal conversion technologies since it is an available source. Therefore, a process for the gasification of poultry litter is examined in this study. This process integrates a fluidised bed gasifier with a gas turbine with the aim of generating combustibles gases for energy production. This resulted in a viable solution for a small scale system to be installed on-site the biomass source. The system allows the treatment of waste with the additional benefit of generation of energy, and is suitable for a poultry farm to avoid the transportation of litter to centralised plants. Among the by-products generated during gasification, such as NOx, SO2, and fly ash, tar is a major issue when implementing this technology because tar can cause operational problems as a result of the possible formation of aerosols and soot formation due to repolymerization. A process simulation using Aspen Plus was used to evaluate four levels of integration. The equilibrium model was applied to evaluate integration schemes involving recuperation of energy from the gas turbine exhaust gases. The recuperation of residual heat to preheat air and product gases was performed with the aim of achieving the highest electrical efficiency. For the conventional "atmospheric layout", the fuel gases have to be cooled down before being compressed to the desire pressure, which causes to waste energy from the hot fuel gases. The benefit of the "pressurised layout" is that all process stages can be maintained hot. Process efficiency analyses showed that even when the "atmospheric layout" was set with energy recuperation, the "pressurised layout" delivered higher efficiencies with or without the energy recuperation into the gasifier. After a bibliographic review, the lignin content of biomass was concluded responsible for tar formation because of its aromatic nature. As lignin components, guaiacol, vanillin and catechol were chosen as tar precursors due to its presence in lignin structure. A reaction mechanism and its corresponding kinetics were derived. This mechanism was based on the three-lignin unit decomposition into lighter molecules and greater aromatic rings. Some of the tar products were involved in combustion and/or steam gasification reactions. The tar reaction mechanism was introduced into the kinetic model for the gasification of poultry litter. The results showed agreement with experimental work from previous reports for the evolution of primary tars. However, the model overestimated the total tar concentration. When the model was compared with the equilibrium model, the trends of the main product gases agreed as the air:fuel ratio was varied.
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Arte Computacional e Teoria Ator-Rede : actantes e associações intersubjetivas em cenaPraude, Carlos Corrêa 30 September 2015 (has links)
Tese (doutorado)—Universidade de Brasília, Instituto de Artes, Programa de Pós-Graduação em Artes, 2015. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2015-11-26T19:01:40Z
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2015_CarlosCorrêaPraude.pdf: 22340686 bytes, checksum: 31dcaba3d1566acf9026ad24b79726ce (MD5) / O objetivo desta pesquisa foi estabelecer associações entre a Teoria Ator-Rede (TAR) e a Arte Computacional. A TAR teve sua origem a partir de pesquisas que investigavam a dinâmica de produção de conhecimento em laboratórios com a utilização de artefatos tecnológicos onde, humanos e nãohumanos, denominados actantes, eram analisados com o mesmo grau de importância. Sob a perspectiva da Estética Informacional, de Abraham Moles e Max Bense, a Arte Computacional encontra seus fundamentos na Teoria da Informação e nos signos que lhe são propostos como objetos. Por meio da metodologia heurística de recodificação de Moles, que consiste na importação de conceitos de uma área de conhecimento para outra, articulei os conceitos conhecidos como actante, associação, tradução e inscrição, da TAR, segundo definições apresentadas por Bruno Latour, com os termos repertório de elementos, mensagem, objeto e estados estéticos, da Estética Informacional. A partir da análise de instalações interativas de minha autoria, sendo a maioria delas aplicadas no campo da encenação teatral, investiguei como as perspectivas da TAR contribuem para a inovação de estados estéticos na produção artística e construí um modelo conceitual dinâmico capaz de colaborar para o processo criativo no território da Arte Computacional. Em um sentido mais amplo e combinatório, ao atualizar a Estética Informacional com os conceitos da TAR, a presente pesquisa propõe uma Estética das Associações, que lança um olhar diferenciado com foco nas conexões que se estabelecem entre os diversos actantes que participam do objeto artístico. / The objective of this research was to establish associations between the Actor-Network Theory (ANT) and Computer Art. ANT originated from researches investigating the dynamics of knowledge production within laboratory with the use of technological artifacts where humans and non-humans, called actants, were analyzed with the same level of importance. Computer Art finds its roots in Information Theory and in the signs systems that are proposed as objects from the perspective of Informational Aesthetics, as stated by Abraham Moles and Max Bense. Throughout Mole’s heuristic methodology process of recoding, which consists in importing the concepts from one area of knowledge into another, I articulated concepts known as actant, association, translation and inscription, from ANT, based on definitions presented by Bruno Latour, with the terms repertoire of elements, message, object and aesthetic states, from Informational Aesthetics. Developing the analysis of interactive installations, of my own creation, most of them being applied in theatrical staging, I investigated how ANT contributes to the innovation of aesthetic states in artistic production and I built a theoretical framework that collaborates to the creative process in terms of Computer Art. Expanding Informational Aesthetics with ANT, this research proposes an Aesthetics of Associations, which takes a different view focusing on the connections established between the actants participating in the art object.
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Caracterização dos produtos da pirólise da casca de castanha de caju = influência da taxa de aquecimento e da temperatura / Characterization of the products from the pyrolysis of the cashew nut shell : influence of heating rate and temperatureFigueiredo, Renata Andrade 17 August 2018 (has links)
Orientadores: Caio Glauco Sanchez, Anne Hélène Fostier / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T20:49:54Z (GMT). No. of bitstreams: 1
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Previous issue date: 2011 / Resumo: O aproveitamento da casca de castanha de caju por meio da conversão térmica pode representar uma solução para o atual problema ambiental de descarte deste resíduo agrícola. Mediante o processo de pirólise, dependendo do tipo de biomassa, a mesma pode ser transformada em liquido, carvão e gases não condensáveis em diferentes proporções. A casca de castanha de caju triturada foi submetida à pirólise em reator de leito fixo, em escala laboratorial. Os experimentos foram realizados em atmosfera inerte (N2), variando a temperatura final (500, 700 e 900 °C) e a taxa de aquecimento (5, 10 e 15 °C/min). Os produtos líquidos (alcatrão+água), sólidos (carvão) e gasosos foram coletados avaliando-se os rendimentos e relacionando-os com os parâmetros previamente estabelecidos. Posteriormente, os produtos foram submetidos a vários testes de caracterização com o objetivo de obter informações que possam contribuir para a sua melhor utilização. O alcatrão foi analisado pela técnica de cromatografia gasosa acoplada a espectrometria de massa (CG-MS). O carvão foi submetido a testes de analise elementar, espectrometria de fluorescência de raio-X (EFRX), microscopia eletrônica de varredura (MEV) e a medida de área superficial por adsorção de N2. Os gases apos coletados foram analisados através de um cromatógrafo com detector de condutividade térmica (CG-DCT). Os resultados mostram que a taxa de aquecimento influi no rendimento e na composição dos produtos obtidos. Quanto a caracterização dos produtos sólidos, os mesmos apresentaram alto poder calorífico, podendo ser utilizado como combustível e características potenciais para serem incorporados ao solo. A fração liquida e composta basicamente de compostos fenólicos, caracterizando o alcatrão como insumo para diversas aplicações. Considerando o poder calorífico do gás produto sem nitrogênio, verifica-se que este pode ser utilizado como combustível em queima direta em caldeiras ou em motores e turbinas apos um pré-tratamento de limpeza / Abstract: The use of cashew nut shell by thermal conversion can represent a solution to the actual environmental problem of the disposal this of agricultural reject. By the process of pyrolysis, process depending on the biomass type, it can be transformed into liquid, char and non- condensable gases in different proportions. On this work, the crushed cashew nuts shells has been submitted to the pyrolysis in fixed bed reactor, at laboratory scale. The experiments have taken place into an inert atmosphere (N2), ranging the final temperature (500, 700 and 900 °C) and heating rate (5, 10 and 15 °C / min). The liquid products (tar and water), solids (char) and gases have been collected evaluating the yields and relating them to previously established parameters. Afterwards, the products have been submitted to a various characterization tests in order to obtain data that can contribute to their better use. The tar has been analyzed by gas chromatography coupled to a mass spectrometry (GC-MS). The char has been submitted to a ultimate analysis, fluorescence spectrometry X-ray (EFRX), electron microscopy of scanning (SEM) and measurement of surface area by adsorption of N2. The gases, after being collected, have been analyzed by a chromatography with thermal conductivity detector (GC-DCT). In order to check the heating rate influence on yield and composition of products obtained. The char obtained has a heating value higher and can be used as fuel characteristics and potential to be incorporated into the soil. As regards the tar composition phenolic compounds are most significant, characterizing the tar as a material for several applications. Considering the heating value of product gas without nitrogen, it appears that it can be used as fuel for direct combustion in boilers or in engines and turbines after a pre-cleaning treatment / Doutorado / Termica e Fluidos / Doutor em Engenharia Mecânica
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Molecular-Size Selective Zeolite Membrane Encapsulated Novel Catalysts for Enhanced Biomass to Liquid (BTL) ProcessesCimenler, Ummuhan 03 April 2017 (has links)
80% of energy usage in the word comes from fossil fuels (coal, oil, natural gas) and among the fossil fuels, oil is the most consumed energy source especially in transportation. However, due to concerns about energy demand and energy sustainability, global warming and dependency on foreign oil, generation of renewable fuels is crucial for transportation. Biomass to Liquid (BTL) is a promising process available to produce renewable liquid fuels. BTL fuels have great potential to meet the growing demand for liquid fuels, mitigating climate change, and providing value to rural areas. However, there are two major challenges with biofuels produced from BTL. One of the major challenge is the H2:CO ratio of biomass gasification product is insufficient for production of hydrocarbon fuels due to formation of methane and tars. The steam reforming of hydrocarbons, to improve the H2:CO ratio, is generally conducted as part of the gas conditioning. However, tars cause the catalysts to deactivate rapidly. Secondly, for fuels produced from the gasification route regardless of feedstock source, there is an economy-of-scale issue. Therefore, it is desirable to seek ways of process intensification to allow small scale plants to be more economical. Zeolites can be used to solve these challenges since they have reactant selectivity property.
To achieve a catalyst capable of reforming methane without potential for deactivation by tars, the encapsulation of a core reforming catalyst with porous zeolite shell is examined in this dissertation. After detailed introduction in the first chapter, a composite H-β zeolite membrane encapsulated 1.6wt%Ni/1.2wt%Mg/Ce0.6Zr0.4O2 steam reforming catalyst was prepared by a physical coating method in the second chapter of the study. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analyses indicated that H-β zeolite was coated successfully on the core reforming catalyst. The pore size of H-β zeolite shell was between 0.43 and 0.57 nm, as measured by the HK method. Steam reforming of CH4 and C7H8 (as a tar model) were conducted with the composite H-β zeolite coated reforming catalyst, the two components individually, and physical mixtures of the two components as a function of temperature (780–840°C). CH4 conversion was enhanced by a factor of 2–3 (depending on temperature) for the composite catalyst as compared to the core reforming catalyst individually even though the zeolite did not have any activity alone. Possible reasons for the enhanced CH4 conversion include confined reaction effects (increase residence time within pores) of the catalyst containing the zeolite coating and/or Al3+ promotion of the active sites. Alternatively, due to molecular-size selectivity, the composite H-β zeolite coated reforming catalyst demonstrated a decrease in C7H8 conversion when compared to the uncoated reforming catalyst. The results validate the use of size selective catalysts to control molecular traffic and enhance the reforming reactant selectivity.
A composite catalyst consisting of an outer layer of zeolite membrane encapsulating an inner reforming catalyst core was synthesized by a double physical coating method to investigate reactant selectivity (ratio of methane/toluene conversion rate) in steam reforming of methane (CH4) and toluene (C7H8). A double encapsulation (51 wt % H-β zeolite) of a 1.6 wt % Ni−1.2 wt % Mg/Ce0.6Zr0.4O2 steam reforming catalyst was compared to a singly coated composite catalyst (34.3 wt % H-β zeolite) to investigate zeolite thickness effects on the conversion of different sized hydrocarbons. The increase in the zeolite content from 34.3 to 51 wt % decreased both CH4 and C7H8 conversions (by up to 14% depending upon the temperature) as a result of the increase in diffusional limitations. Weisz−Prater criteria and Thiele moduli calculations confirmed that the reactions were performed under internal diffusion limitations. The C7H8 conversion of the 51 wt % composite (SR@β51%) catalyst was similar to the zeolite alone, indicating negligible contribution from the protected catalyst core. The reactant selectivity increased by up to 1.5 times on SR@β51% in comparison to the SR@β34.3% composite. Combined reforming at 800 °C on the SR@β51% catalyst indicated that the catalyst was stable during the 10 h time on stream.
Continuing this work, a non-acidic Silicalite-1 zeolite membrane encapsulated 1.6wt%Ni-1.2wt%Mg/Ce0.6Zr0.4O2 steam reforming composite catalyst, synthesized by a physical coating method, was used to investigate effect of encapsulation on size selective steam reforming, using methane (CH4) and toluene (C7H8) as representative species. Weisz-Prater Criteria and Thiele moduli calculations indicated internal diffusion limitations. Combined reforming of CH4 and C7H8 at 800°C on the composite catalyst demonstrated stability during the 10 h time on stream while uncoated SR catalyst deactivated. The non-acidic Silicalite-1 encapsulated catalyst showed decreases (~2-7%) in both CH4 and C7H8 conversions compared to acidic H-β zeolite confirming that shell acidity did contribute to conversion and suggesting that shell defects/grain boundaries were responsible for the C7H8 conversion.
Finally, low temperature 0.16wt%Pt–1.34wt%Ni–1.00wt%Mg/(Ce0.6Zr0.4)O2 reforming catalyst was triple coated with H-β zeolite (60 wt% of zeolite) to be utilized synthesis of combination steam reforming catalyst (SR) and Fischer-Tropsch Synthesis (FTS) catalyst (CRAFT) for a single-step conversion of methane to liquid fuels. Scanning electron microscopy (SEM) image and energy-dispersive spectroscopy (EDS) analysis result demonstrated that H-β zeolite was successfully encapsulated onto the low temperature reforming catalyst. The catalyst was tested in steam reforming of methane (CH4) and toluene (C7H8) and the results was compared with 51 wt%. While CH4 conversions are very similar on the 60wt% composite catalyst with 51wt% composite catalyst, no C7H8 conversion was seen on the 60 wt% composite catalyst. Thus, it is concluded that the 60 wt% composite catalyst can be utilized to synthesis CRAFT catalyst.
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Characterization of medium temperature gasifier pitchPapole, Gedion John 15 November 2012 (has links)
Pitches are important precursors for carbon materials. They are usually obtained by thermal treatment of petroleum and coal fractions. Pitches have higher carbon content and are capable of developing into graphitisable carbons upon heat treatment. Petroleum pitches are generally less aromatic than coal tar pitches. Medium-temperature gasifier pitch (MTP), from Sasol’s Lurgi process, is a potential precursor for graphitisable carbon. MTP showed a high degree of solubility in several organic solvents, namely dimethylformamide, quinoline, tetrahydrofuran, pyridine, morpholine, benzene, toluene, xylene and acetone. It was virtually insoluble in n-hexane, cyclohexane, cyclohexanol, acetonitrile and formamide. MTP pitch was partially soluble in methanol and had a solubility limit of 40 g/l at ambient temperature. MTP samples were spiked with boron to make 1000 ppm B-containing samples. The boron distribution coefficient was defined as the ratio of the boron contents of the insoluble pitch residue to the methanol-soluble pitch extracts, using a mass balance. This justified the decision to define the apparent boron partition coefficients based on the boron content of the recovered pitch residues. 4-(dibenzofuranyl) boronic acid (DBA), 2 phenoxyphenyl boronic acid (PBA), p-tolylboronic acid (TBA) and phenylboronic acid (PLA) were retained the most in the residues after methanol extraction. Over 500 ppm of PBA, TBA and PLA were retained in the pitch residues following methanol extraction. The results showed that methanol extracted substituted boron acid model compounds. Methanol dissolved mostly low molecular mass/aliphatic species, which are not important for graphitisation. The thermomechanical analysis (TMA) results showed that MTP has a low softening point compared with the methanol-insoluble (MI) fractions. The attenuated total reflectance (ATR) results showed that the benzene-insoluble (BI), toluene-insoluble (TI) and MI fractions had more intense aromatic C–H stretching peaks than their corresponding soluble fractions. Elemental analysis and the solid-state 13C nuclear magnetic resonance (NMR) results revealed that the benzene-, toluene- and methanol-insoluble fractions are more aromatic than their corresponding soluble fractions. The order of the aromaticity index for the insoluble fractions was as follows: MTP<MI<TI<BI. Matrix-assisted laser desorption (MALDI) analysis of the mass distribution revealed that the majority of compounds in MTP and its soluble and insoluble fractions were in the low molecular mass range, i.e. 190–388 atomic mass units. The thermal analysis results showed that the benzene-, toluene- and methanol-insoluble fractions were thermally stable and had higher carbon yields than their corresponding soluble fractions. MTP was thermally more stable than the methanol-, toluene- and benzene-soluble fractions. Evaluation of the polycyclic aromatic hydrocarbons (PAHs) by gas chromatography-mass spectrometry (GC-MS) showed that the methanol-insoluble fractions had lower PAH contents than MTP and MI. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Chemistry / unrestricted
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Permission to Pollute: Regulating Environmental Corporate Crime in the Alberta Tar SandsAlexander, Chloe January 2015 (has links)
This study explores how the Canadian and Alberta governments downplay environmental harm in the Alberta Tar Sands, therein justifying its ongoing expansion and defining it as unnecessary to intervene through the law. In particular, this study draws on the concepts of hegemony, social harm and deep ecology to problematize how climate change has become the governments’ main environmental concern in the tar sands, despite the existence of other, equally troubling issues, and how carbon capture and storage (CCS) has become the states’ main climate change strategy, despite the largely untested nature of this technique. A critical discourse analysis of two government taskforce documents concerning CCS technology revealed that neoliberal and globalization discourses were used to narrowly conceptualize environmental harm, thereby privileging Canada’s trade relations and economic strength over the environment’s health. Relatedly, discourses of scientism were used to conceptualize climate change as a technical problem and CCS as the “preferred” solution.
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Rheological Behaviour and Characterisation of Pitch-Based Carbon PrecursorsRamjee, Shatish January 2015 (has links)
Pitch material is an important precursor in the production of carbon bre, carbon composites
and synthetic graphite. It has a complex transformation during pyrolysis which
incorporates the separation of a liquid crystalline phase, known as mesophase. This thesis
attempts to enhance the understanding of this change in composition, structure and its
resultant behaviour.
In this study, two pitches, a coal-tar pitch (MP110) and a (SASOL) Lurgi-gasi er
pitch, are pyrolised to produce material at di erent stages of mesophase development.
These pitches produce mesophase of di erent mosaic type and therefore also resultant
coke.
The MP110 was thermally treated up to a temperature of 437 and produced
anisotropic pitch (which still contains signi cant particulate matter). The nucleated
mesophase spheres did not coalesce to produce domains; this behaviour being attributed
to the particulate material. The SASOL pitch produced a di erent type of mesophase
material. The mesophase produced was of ne mosaic domains; a sample with continuous
mesophase regions was also produced with a mesophase content of approximately 60%
(by volume).
The aromatic starting material of MP110 produced higher quinolone and toluene
insoluble (QI and TI) compounds after pyrolysis. This was also observed in the increase
of C/H (molar ratio of carbon to hydrogen). The more aliphatic SASOL starting pitch
showed similar trends to its MP110 counterparts with respect to QI (quinoline insolubles),
TI (toluene insolubles) and C/H. The glass transition and associated temperatures of
the pitches were analysed via thermal mechanical analysis (TMA), dynamic scanning
calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The techniques
showed consistency between instruments, with TMA providing the likeliest re
ection of
the true thermodynamic glass transition temperature. The loss of volatile components
was accompanied by an increase in glass transition temperature (observed in conjunction with C/H and mesophase content). For anisotropic MP110 pitches, two relaxations were
observed, one for the isotropic fraction, the other for the mesophase. No such behaviour
was easily observed for the SASOL pitches.
Rheological measurements were obtained to understand the behaviour of the pitches.
Measurements were limited to a speci c viscosity range. The measurements of the samples
were therefore made at di erent temperatures. The relation of the measurement
temperature to the glass transition temperature is thus of extreme importance. The
temperature governs the state of the structure; whether it be suspension, emulsion or gel.
Oscillatory shear experiments were undertaken for the pitch material. Predominantly
isotropic material showed transition from viscoelastic solid to viscoelastic liquid as previously
observed in pitch material.
The anisotropic MP110 pitches did not allow for the production of mastercurves due
to non-linear viscoelastic e ects caused by the softening of mesophase. This being the
transition from a suspension of hard spheres to an emulsion of deformable droplets (depending
on temperature).
For the higher mesophase content anisotropic SASOL pitches, mastercurves were produced;
it had a similar shape to the isotropic pitches (at temperatures closer to the
glass transition), but signi cantly increased elasticity was observed at higher temperatures.
This phenomenon supported the hypothesis of a strong interaction between the
components and phases of the pitch, and thus the possibility of gelled systems.
Rotational shear-rheometry was also utilised and showed that isotropic pitch material
behaves as a predominantly isoviscous
uid.
The anisotropic MP110 pitches of approximately 30% mesophase showed high- and
low-shear viscosity plateau
uid behaviour. This being caused by the breakup of agglomerated
mesophase spheres. This was tested by the implementation of the Krieger-
Dougherty suspension model. The possibility of droplet deformation was investigated
for these samples by utilising a Krieger-Douherty based emulsion analogue, which con-
rmed suspension like behaviour (at the measured temperatures). MP110 samples with
more mesophase were measured at higher temperatures. Their behaviour is more akin to
Power-law shear-thinning behaviour. Being further away from the continuous isotropic
phase glass transition temperature, the behaviour observed is similar to that of emulsions.
SASOL anisotropic pitches showed signi cant yielding upon shear, which is attributed
to structure breakdown. This behaviour is appropriately described by a yield stress, shearthinning
model such as Herschel-Bulkley. Measurements of viscosity for these samples
were made at temperatures signi cantly further from the glass transition temperature as
compared to that of the MP110 pitches. This corroborates strong interaction between
its components. The observed shapes of the curve, at temperatures of measurement,
support the notion of a gel structure. This behaviour is rst proposed via the complex
structure observed (clusters of ne mosaic mesophase domains) and supported by strong interaction of the components inferred from obtained rheological properties. / Thesis (PhD)--University of Pretoria, 2015. / tm2015 / Chemical Engineering / PhD / Unrestricted
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