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Estudo do processo de absorção de CO2 em soluções de aminas empregando-se coluna recheada. / Study of CO2 process absorption into aqueous alkanolamines in packed tower.Mello, Lilian Cardoso de 06 August 2013 (has links)
Objetivo deste trabalho foi o de caracterizar e estudar o processo de transferência de massa da absorção de CO2 em soluções aquosas de aminas em coluna recheada operando em pressão atmosférica. Com este objetivo, construíram-se dois equipamentos, sendo um constituído de coluna em escala laboratório com recheio estruturado e outro de uma coluna em escala piloto com recheio randômico. Empregou-se a absorção de CO2, diluído em ar, em solução de NaOH, para a determinação da área interfacial efetiva. Os coeficientes globais de transferência de massa foram determinados para a absorção de CO2, diluído em ar, em diferentes soluções aquosas absorvedoras a base de aminas, a saber: 25% em massa de MEA, MEA-MDEA nas concentrações mássicas 5% MDEA 25% MEA, 10% MDEA 20% MEA e 15% MDEA 15% MEA. Constatou-se uma forte correlação entre a proporção da solução MDEA-MEA e o coeficiente global de transferência de massa. O planejamento dos ensaios em coluna piloto foi realizado com o emprego de simulador de processos, para a verificação hidrodinâmica da coluna e especificação das vazões de gás e de solução absorvente. Compararam-se, também, os resultados obtidos experimentalmente com os previstos pela simulação, no caso da absorção em MEA. / The aim of the present work was to characterize and study the mass transfer process of the CO2 absorption into single and blended alkanolamines in a packed column under atmospheric pressure. For this purpose, two systems were built, one of the columns is a laboratory structure packed column and the other is a pilot random packed column. The absorption of CO2 into NaOH was performed to determine the effective mass-transfer area and the overall mass-transfer coefficient. The absorption performance was evaluated in terms of the overall mass-transfer coefficient for the absorption of CO2 in air into single and blended alkanolamines: MEA 25% wt, and MEA-MDEA mixtures, MEA-MDEA (25% /5% wt), MEA-MDEA (20% /10% wt) and MEA-MDEA (15% /15% wt). The CO2 absorption performance of MEA-MDEA mixture has a high correlation with the proportion MEA-MDEA. Experimental series were designed employing a process simulator for the hydrodynamic checking and determination of gas and liq flow rates. Comparison of the experimental data and simulation results was made for the absorption into MEA.
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Digital Control and Monitoring Methods for Nonlinear ProcessesHuynh, Nguyen 09 October 2006 (has links)
"
The chemical engineering literature is dominated by physical and (bio)-chemical processes that exhibit complex nonlinear behavior, and as a consequence, the associated requirements of their analysis, optimization, control and monitoring pose considerable challenges in the face of emerging competitive pressures on the chemical, petrochemical and pharmaceutical industries. The above operational requirements are now increasingly imposed on processes that exhibit inherently nonlinear behavior over a wide range of operating conditions, rendering the employment of linear process control and monitoring methods rather inadequate. At the same time, increased research efforts are now concentrated on the development of new process control and supervisory systems that could be digitally implemented with the aid of powerful computer software codes. In particular, it is widely recognized that the important objective of process performance reliability can be met through a comprehensive framework for process control and monitoring. From:
(i) a process safety point of view, the more reliable the process control and monitoring scheme employed and the earlier the detection of an operationally hazardous problem, the greater the intervening power of the process engineering team to correct it and restore operational order
(ii) a product quality point of view, the earlier detection of an operational problem might prevent the unnecessary production of o-spec products, and subsequently minimize cost.
The present work proposes a new methodological perspective and a novel set of systematic analytical tools aiming at the synthesis and tuning of well-performing digital controllers and the development of monitoring algorithms for nonlinear processes. In particular, the main thematic and research axis traced are:
(i) The systematic integrated synthesis and tuning of advanced model-based digital controllers using techniques conceptually inspired by Zubov’s advanced stability theory.
(ii) The rigorous quantitative characterization and monitoring of the asymptotic behavior of complex nonlinear processes using the notion of invariant manifolds and functional equations theory.
(iii) The systematic design of nonlinear state observer-based process monitoring systems to accurately reconstruct unmeasurable process variables in the presence of time-scale multiplicity.
(iv) The design of robust nonlinear digital observers for chemical reaction systems in the presence of model uncertainty. "
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Absorption-désorption des gaz acides par des solutions aqueuses d'aminesCadours, Renaud 23 September 1998 (has links) (PDF)
Une cellule à interface gaz-liquide fixe a été conçue pour la mesure de flux de désorption de dioxyde de carbone à partir de solutions aqueuses d'amines. Les expériences ont été réalisées pour des températures comprises entre 40°C et 110°C, pour des taux de charge en gaz acide compris entre 0,05 et 0,85 molCO2/molamines, à partir de solutions aqueuses de MDEA 25 % et 50 % massiques et de mélanges MDEA-DEA de composition 45-5 et 30-20 % massiques. L'utilisation d'une méthode analytique faisant intervenir des approximations thermodynamiques et cinétiques permet de représenter les flux de désorption expérimentaux obtenus avec les solutions aqueuses de MDEA pour des taux de charge inférieurs à 0,50 molCO2/molMDEA. Il est apparu nécessaire de coupler un modèle de transfert prenant en compte les réactions chimiques avec un modèle thermodynamique représentant les équilibres physiques et chimiques des systèmes CO2-H2O-Amines. Un outil numérique a alors été développé pour représenter les phénomènes de transfert en présence de réactions chimiques. Les profils de concentration de chaque espèce et le flux de transfert de l'espèce transférée à l'interface gaz-liquide sont obtenus à partir de la résolution des équations de bilan de masses. Ce modèle cinétique, combiné avec un jeu de paramètres adéquats, a été appliqué avec succès à la représentation de l'absorption de CO2 par des solutions aqueuses de MDEA et des mélanges aqueux de MDEA-DEA et MDEAMEA. En couplant des paramètres cinétiques et thermodynamiques cohérents, cet outil permet de représenter les flux de désorption mesurés dans la cellule à interface constante.
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Sintese e marcacao com P-32 de fosfatos de monoalquila e do fosfato de monofenila sob forma de sais de bis-ciclohexilamonio. Determinacao de espectros de absorcao em infra-vermelho e de ressonancia nuclear magneticaALMEIDA, MARIA A.T.M. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:23:11Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:29Z (GMT). No. of bitstreams: 1
00636.pdf: 4746331 bytes, checksum: 49aa6e0eb3bdd9da261862a04bcb4b58 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
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Sistema calorimétrico e software para análise da polimerização de compostos de metacrilato de metila, pela variação da exotermia da reação / Calorimetric system and software for analysis of polymerization of methyl methacrylate compounds, the variation exotherm reactionRIBEIRO, MARCOS S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:42:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:44Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Estudo do processo de absorção de CO2 em soluções de aminas empregando-se coluna recheada. / Study of CO2 process absorption into aqueous alkanolamines in packed tower.Lilian Cardoso de Mello 06 August 2013 (has links)
Objetivo deste trabalho foi o de caracterizar e estudar o processo de transferência de massa da absorção de CO2 em soluções aquosas de aminas em coluna recheada operando em pressão atmosférica. Com este objetivo, construíram-se dois equipamentos, sendo um constituído de coluna em escala laboratório com recheio estruturado e outro de uma coluna em escala piloto com recheio randômico. Empregou-se a absorção de CO2, diluído em ar, em solução de NaOH, para a determinação da área interfacial efetiva. Os coeficientes globais de transferência de massa foram determinados para a absorção de CO2, diluído em ar, em diferentes soluções aquosas absorvedoras a base de aminas, a saber: 25% em massa de MEA, MEA-MDEA nas concentrações mássicas 5% MDEA 25% MEA, 10% MDEA 20% MEA e 15% MDEA 15% MEA. Constatou-se uma forte correlação entre a proporção da solução MDEA-MEA e o coeficiente global de transferência de massa. O planejamento dos ensaios em coluna piloto foi realizado com o emprego de simulador de processos, para a verificação hidrodinâmica da coluna e especificação das vazões de gás e de solução absorvente. Compararam-se, também, os resultados obtidos experimentalmente com os previstos pela simulação, no caso da absorção em MEA. / The aim of the present work was to characterize and study the mass transfer process of the CO2 absorption into single and blended alkanolamines in a packed column under atmospheric pressure. For this purpose, two systems were built, one of the columns is a laboratory structure packed column and the other is a pilot random packed column. The absorption of CO2 into NaOH was performed to determine the effective mass-transfer area and the overall mass-transfer coefficient. The absorption performance was evaluated in terms of the overall mass-transfer coefficient for the absorption of CO2 in air into single and blended alkanolamines: MEA 25% wt, and MEA-MDEA mixtures, MEA-MDEA (25% /5% wt), MEA-MDEA (20% /10% wt) and MEA-MDEA (15% /15% wt). The CO2 absorption performance of MEA-MDEA mixture has a high correlation with the proportion MEA-MDEA. Experimental series were designed employing a process simulator for the hydrodynamic checking and determination of gas and liq flow rates. Comparison of the experimental data and simulation results was made for the absorption into MEA.
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Sintese e marcacao com P-32 de fosfatos de monoalquila e do fosfato de monofenila sob forma de sais de bis-ciclohexilamonio. Determinacao de espectros de absorcao em infra-vermelho e de ressonancia nuclear magneticaALMEIDA, MARIA A.T.M. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:23:11Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:29Z (GMT). No. of bitstreams: 1
00636.pdf: 4746331 bytes, checksum: 49aa6e0eb3bdd9da261862a04bcb4b58 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
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The dynamics of chemically active dropletsSeyboldt, Rabea 16 June 2020 (has links)
In unserem täglichen Leben begegnen wir Tropfen oft in physikalischen Systems, beispielsweise als Öltropfen in Salatsoße. Diese Tropfen sind meist chemisch inaktiv. In biologischen Zellen bilden Proteine und RNA zusammen Tropfen. Zellen sind chemisch aktiv, so dass die Tropfenkomponenten neu gebildet, abgebaut und modifiziert werden können.
In dieser Doktorarbeit wird das dynamische Verhalten von chemisch aktiven Tropfen mit analytischen und numerischen Methoden untersucht. Um das dynamische Verhalten von solchen aktiven Tropfen zu untersuchen, benutzen wir ein Minimalmodell mit zwei Komponenten, die zwei Phasen bilden und durch chemische Reaktionen ineinander umgewandelt werden. Die chemischen Reaktionen werden durch das Brechen von Detailed Balance aus dem Gleichgewicht gehalten, so dass die Tropfen chemisch aktiv sind. Wir konzentrieren uns auf den Fall, in dem Tropfenmaterial im Tropfen in die äußere Komponente umgewandelt wird, und in der äußeren Phase erzeugt wird.
Wir finden ein vielfältiges dynamisches Phasendiagramm mit Regionen, in denen Tropfen schrumpfen und verschwinden, Regionen, in denen Tropfen eine stabile stationäre Größe besitzen, und Regionen, in denen eine Forminstabilität zu komplexer Tropfen-Dynamik führt. In der letzten Region deformieren sich Tropfen typischenweise prolat, verformen sich zu einer Hantel, und teilen sich in zwei Tochtertropfen, die wieder anwachsen. Dies kann zu Zyklen von Wachstum und Teilung von Tropfen führen, bis die Tropfen das gesamte Volumen füllen. Während spherische Tropfen durch die chemischen Reaktionen entgegen ihrer Oberflächenspannung deformiert werden, können Tropfen- Zylinder und Platten durch chemische Reaktionen stabilisiert werden.
Generell ist die Dynamik von Tropfen ein hydrodynamisches Problem, da die Oberflächenspannung von deformierten Tropfen hydrodynamische Flüsse erzeugt. Wir finden, dass chemische Reaktionen entgegen die Oberflächenspannung Arbeit verrichten können, so dass die Tropfenteilung auch unter Berücksichtigung hydrodynamischer Flüsse möglich ist.
Diese Doktorarbeit zeigt, dass die Kombination von chemische Reaktionen und Phasenseparation unter Nichtgleichgewichtsbedingungen zu neuem dynamischen Verhalten führen kann. Die Ergebnisse zeigen die Relevanz von chemischen Reaktionen zum Verständnis von Phasenseparation in biologischen Systemen auf, und können bei der Umsetzung der diskutierten Phänomene in experimentellen Systemen helfen. Die Tropfenteilung, die in dieser Doktorarbeit diskutiert wird, erinnert an die Teilung von biologischen Zellen. Davon motiviert schlagen wir vor, dass die Teilung von chemisch aktiven Tropfen ein Mechanismus für die Replikation von Tropfen-artigen Protozellen am Ursprung des Lebens gewesen sein könnte.:1. Introduction
2. Theory of multi-component phase-separating systems with chemical reactions
3. Minimal model for chemically active droplets in two formulations
4. Shape instability of spherical droplets with chemical reactions
5. Dynamical behavior of chemically active droplets
6. Shape instability of droplets with various geometries
7. Role of hydrodynamic flows in chemically driven droplet division
8. Chemically active droplets as a model for protocells at the origin of life
9. Conclusion
Appendices / In our everyday environment, we regularly encounter liquid-liquid phase separation in physical systems such as oil droplets in vinegar. These droplets tend to be chemically inert. In biological cells, protein and RNA may together form liquid droplets. Cells are chemically active, so that droplet components can be created, degraded and modified.
In this thesis we study the influence of nonequilibrium chemical reactions on the shape dynamics of a droplet theoretically, using analytical and numerical methods. To discuss the dynamical behavior that results from combining phase separation and chemical reactions in sustained nonequilibrium conditions, we introduce a minimal model with only two components that separate into distinct phases. These two components are converted into each other by chemical reactions. The reactions are kept out of equilibrium by breaking of detailed balance, so that the droplet becomes active. We concentrate on the case where the reaction inside the droplet degrades droplet material into the outer component, and where the reaction outside creates new droplet material.
We find that chemically active droplets have a rich dynamic phase space, with regions where droplets shrink and vanish, regions where droplets have a stable stationary size, and regions where the flux-driven instability leads to complex dynamic behavior of droplets. In the latter, droplets typically elongate into a dumbbell shape and then split into two symmetrical daughter droplets. These droplets then grow until they have the same size as the initial droplet. This can lead to cycles of growth and division, so that an initial droplet divides until droplets fill the simulation volume. We analyze the stationary spherical state of the droplet, which is created by a balance of the fluxes driven by the chemical reactions. We find that stationary droplets may have a shape instability, which is driven by the continuous fluxes across the droplet interface and which may trigger the division. We also find that while reactions may destabilize spherical droplet shapes despite the surface tension of the droplet, they can have stabilizing effects on cylindrical droplets and droplet plates.
Generally, the shape dynamics of droplets is a hydrodynamic problem because surface tension in non-spherical droplets drives hydrodynamic flows that redistribute material and deform the droplet shape. We therefore study the influence of hydrodynamic flows on the shape changes of chemically active droplets. We find that chemical reactions in active droplets can perform work against surface tension and flows, so that the droplet division is possible even in the presence of hydrodynamic flows.
The present thesis highlights how the combination of basic physical behaviors – phase separation and chemical reactions – may create novel dynamic behavior under sustained nonequilibrium conditions. The results demonstrate the importance of considering chemical reactions for understanding the dynamics of droplets in biological systems, as well as proposes a minimalist model for experimentalists that are interested in creating a system of dividing droplets. Finally, the division of chemically active droplets is reminiscent of the division of biological cells, and it motivates us to propose that chemically active droplets could have provided a simple mechanism for the self-replication of droplet-like protocells at the origin of life.:1. Introduction
2. Theory of multi-component phase-separating systems with chemical reactions
3. Minimal model for chemically active droplets in two formulations
4. Shape instability of spherical droplets with chemical reactions
5. Dynamical behavior of chemically active droplets
6. Shape instability of droplets with various geometries
7. Role of hydrodynamic flows in chemically driven droplet division
8. Chemically active droplets as a model for protocells at the origin of life
9. Conclusion
Appendices
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A universal transfer route for grapheneGorantla, Sandeep, Bachmatiuk, Alicja, Hwang, Jeonghyun, Alsalman, Hussain A., Young Kwak, Joon, Seyller, Thomas, Eckert, Jürgen, Spencer, Michael G., Rümmeli, Mark H. 02 December 2019 (has links)
Often synthetic graphene requires transfer onto an arbitrary substrate prior to use because the substrate it was originally synthesized on is inappropriate for either electrical measurement or characterization. While a variety of routes have been developed they are substrate dependant and often involve the use of harsh treatments. Here we present a facile and cheap route that can be applied to graphene over any substrate. This universal transfer route is based on a wet chemical reaction producing gaseous species which can intercalate between the substrate and the graphene and thus gently delaminate the two.
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An Exergetic Comparison of Copper Extraction from Chalcopyrite Concentrates by Pyrometallurgy and HydrometallurgyPaul Mather (9464987) 16 December 2020 (has links)
Copper is an essential metal in today’s economy, due to its superior electrical and thermal conductivities, alloying properties, and chemical uses. Most copper is produced viamining and refining, and most copper is found in the earth’s crust as chalcopyrite, CuFeS2. Typically, chalcopyrite is concentrated and fed to a high temperature pyrometallurgical process which produces >99.99% purity copper cathodes. Recently, Freeport-McMoRan Inc. has implemented a hydrometallurgical autoclave-leaching process that takes chalcopyrite concentrate and produces copper cathodes. It is imperative that these pyrometallurgical and hydrometallurgical processes be modeled and compared so that the extraction industry can best decide which technology to apply in the future. This work presents transient, reduced-order models for the comparison of the two processes using exergy balances. Exergy is typically thought of as the maximum work extractable from a system as it spontaneously reacts to the state of the surrounding environment; for extractive processes, it is also helpful to think of exergy as the minimum work required to effect a concentration, e.g. of copper. Exergy balances are thus similar to first law balances, but they comment on the location and magnitude of usefulenergy flows, instead of energy flows in general. For the baseline case, this work found that the pyrometallurgical process up to 99.5% copper anode stored 54% of the fed exergy in product, lost 20% of the fed exergy, and destroyed the remaining 26%. In contrast, the hydrometallurgical process up to 30 grams-per-liter copper pregnant-leach-solution stored 5% of the fed exergy in product, lost 9% of the fed exergy, and destroyed the remaining 86%. The effects of process variations are also looked at. It is recommended that this work be incorporated in whole-plant exergy balances to more precisely examine the tradeoffs between the pyrometallurgical and hydrometallurgical routes of copper extraction from chalcopyrite concentrates.
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