Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 55-56).

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Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Supercritical fluids are enjoying ever increasing popularity as a solvent medium for extraction, stripping and absorption processes. Being readily tuneable and able to achieve sharp, highly efficient separations, supercritical fluids present an attractive alternative to traditional solvents, while using less intrinsically harmful compounds. Although the potential of supercritical fluids as solvents have been known for more than a century, there are still several areas of uncertainty, one being the hydrodynamics of extraction columns operating under supercritical conditions. This shortcoming can be attributed to the satisfactory performance of modified standard hydrodynamics to approximate column design, along with a predominant culture of overdesign in process engineering. Even though modified subcritical hydrodynamic models provide a good approximation they do not successfully predict the effect of changes in density, viscosity and surface tension of a supercritical fluid, leading to inaccuracies in column design. This study investigates the state of hydrodynamics under supercritical conditions in counter current packed columns discussed in literature, identifies shortcomings in existing literature and devises a way of addressing the said shortcomings. The primary objective of this study is to establish a multipurpose supercritical pilot plant capable of measuring hydrodynamics under supercritical conditions, followed by the secondary objective of measuring preliminary hydrodynamic data to prove the plant can deliver on its design requirements in measuring reliable hydrodynamic data. During a survey of available literature it was found that very little experimental work has been performed on hydrodynamics under supercritical conditions and especially on random packings. Further it is found that the systems investigated in literature were conducted under conditions of significant mass transfer. As mass transfer directly affects flow rates and fluid properties of the fluids in the column, it is vital to use systems with very little to no mass transfer. This ensures the most accurate approach possible when investigating fundamental hydrodynamic behaviour. Finally it was found that there are no well-defined correlations available for a wide range of packings, fluid properties and hydrodynamic phenomena for columns under supercritical conditions. To remedy the shortcomings in hydrodynamic data it was decided that more pilot plant work is required. It was found that no pilot plants available can measure hydrodynamic data. An investigation was performed into retrofitting available pilot plants, plants used by other research groups and commercially available plants. It was concluded that the best option was to salvage the major parts of an existing old pilot plant and use them to construct a new, customized pilot plant. This provides the opportunity of constructing a custom, multipurpose pilot plant capable of use in future research. After an initial concept design a full design of the new pilot plant was performed. The plant consists of two columns of 17 mm and 38 mm inside diameter and 3.5 m and 1.5 m packed height, respectively, and is capable of pressures and temperatures of up to 300 bar and 200°C. Furthermore the pilot plant can measure liquid hold-up, pressure drop, flooding and entrainment in accordance with the objective of measuring supercritical hydrodynamic data. Liquid hold-up was determined by stopping the process and allowing the column to drain, after which the volume drained was measured. To measure the pressure drop an Endress+Hauser Deltabar S PMD75 DP cell was used. Flooding was determined using the measured pressure drop and volumetric rate of column overheads, from where a hydrodynamically inoperable state is defined. Overall entrainment, although unlikely due to the presence of a demister in the column, was investigated by comparing the column overheads to literature phase equilibria. Preliminary hydrodynamic testing was performed using the 38mm diameter column packed with 1/4” Dixon rings. Testing is performed with at 120 bar and 40°C with a CO2 supercritical phase and polyethylene glycol liquid phase with an average molar mass of 400 (PEG 400). The hydrodynamic data gathered showed expected trends, but showed discrepancy with literature due to differences in liquids used, column packing and experimental system between the respective studies. / AFRIKAANSE OPSOMMING: Superkritiese vloeistowwe is besig om toenemende gewildheid as 'n oplosmiddel vir ekstraksie, stroping en absorpsie prosesse te geniet. Hierdie gewildheid is as gevolg van ʼn vermoë om skerp, hoogs effektiewe skeidings te bewerkstellig deur gebruik te maak van ʼn maklik aanpasbare oplosmiddel wat minder intrinsiek skadelik is as tradisionele oplosmiddels. Hierdie voordele lei daartoe dat superkritiese vloeiers as ʼn aantreklike alternatief tot tradisionele oplosmiddels gesien kan word. Alhoewel die potensiaal van superkritiese vloeistowwe as oplosmiddels al vir meer as ʼn eeu bekend is, is nog weinig eksperimentele werk al gedoen oor die hidrodinamiese gedrag van superkritiese gepakte kolomme. Hierdie tekortkoming kan toegeskryf word tot die bevredigende prestasie van aangepaste standaard hidrodinamiese korrelasies gedurende superkritiese kolomontwerp en ʼn oorheersende kultuur van oorontwerp in proses-ingenieurswese. Alhoewel aangepaste standaard hidrodinamiese korrelasies ʼn aanvaarbare benadering bied, beeld dit nie die effek van die veranderde digtheid, viskositeit en oppervlakspanning van ʼn superkritiese vloeistof uit nie, wat lei tot foute in kolomontwerp. Hierdie studie ondersoek die stand van superkritiese hidrodinamika in literatuur, spesifiek in teenstroom gepakte kolomme. Tekortkominge in die bestaande literatuur is geïdentifiseer en 'n metode om die genoemde tekortkominge reg te stel is bedink. Die primêre doel van hierdie studie is om 'n veeldoelige superkritiese loodsaanleg te bou wat tot staat is om superkritiese hidrodinamika te meet, gevolg deur die sekondêre doelwit wat die meet van voorlopige hidrodinamiese data behels, wat sal bewys dat die loodsaanleg voldoen aan ontwerpsvereistes. Tydens 'n opname van beskikbare literatuur was daar gevind dat weinig eksperimentele werk al gedoen is in die veld van superkritiese hidrodinamika, en nog minder oor sogenoemde ongeordende of ‘random’ kolompakkings. Verder is daar gevind dat eksperimente uitgevoer in literatuur slegs bestaan uit stelsels waar beduidende massa-oordrag plaasvind. Aangesien massa-oordrag die vloeitempo en fisiese eienskappe van die vloeiers in ʼn kolom direk beïnvloed, is dit noodsaaklik om gebruik te maak van stelsels met baie min of geen massaoordrag. Dit verseker ʼn akkurate benadering tot die meet van fundamentele hidrodinamiese gedrag. Laastens is gevind dat daar geen hidrodinamiese korrelasies beskikbaar is wat ʼn wye verskeidenheid van kolompakkings, vloeier eienskappe en hidrodinamiese verskynsels onder superkritiese toestande dek nie. Om die tekortkominge in superkritiese hidrodinamika in literatuur aan te spreek, word meer eksperimentele loodsaanlegwerk vereis. Daar is gevind dat geen van die beskikbare loodsaanlegte hidrodinamiese data kan meet nie. Ondersoek is ingestel tot die ombouing van bestaande loodsaanlegte, aanlegte wat gebruik is deur ander navorsingsgroepe en kommersieel beskikbare aanlegte. Daar is tot die gevolgtrekking gekom dat die beste opsie is om ʼn nuwe loodsaanleg self te bou en gebruik te maak van parte uit een van die ou bestaande aanlegte om kostes laag te hou. Sodoende kan ʼn veeldoelige, pasgemaakte loodsaanleg gebou word wat ook vir toekomstige navorsing gebruik kan word. Na ʼn aanvanklike konsep ontwerp vir die nuwe loodsaanleg, is ʼn volledige ontwerp gedoen. Die aanleg bestaan uit twee kolomme van onderskeidelik 17 mm en 38 mm binnedeursnee en 3,5 m en 1,5 m gepakte hoogte, en is in staat om eksperimente by ʼn maksimum druk en temperatuur van tot 300 bar en 200°C uit te voer. Verder is die loodsaanleg in staat daartoe hidrodinamiese data te meet, naamlik die vloeistofophoud in die kolom, drukval oor die kolompakking, kolomvloed en druppel meesleuring. Die vloeistofophoud in die kolom is bepaal deur alle voer tot die kolom te stop en tyd toe te laat vir die vloeistof om te dreineer, waarna die gedreineerde afgetap en gemeet is. Om die drukval te meet word ʼn Endress+Hauser Deltabar S PMD75 DP sel gebruik. Kolomvloed is bepaal met behulp van die drukval oor die kolom en die vloeitempo van die kolom se boonste produkstroom, van waar ʼn hidrodinamies onbruikbare toestand gedefinieer word. Algehele druppel meesleuring, alhoewel onwaarskynlik as gevolg van die teenwoordigheid ʼn ontwasemer in die kolom, is wel ondersoek deur die vloeistofinhoud in die kolom se boonste produkstroom te vergelyk met fase ewewigsdata in literatuur. Voorlopige hidrodinamiese eksperimente is uitgevoer met behulp van die 38mm deursnee kolom gepak met 1/4 " Dixon ringe. Eksperimente is uitgevoer by 120 bar en 40 ° C met 'n CO2 kritiese fase en 'n poliëtileenglikol vloeistof fase met ʼn gemiddelde molêre massa van 400 (PEG 400). Die hidrodinamiese data het verwagte tendense getoon, maar diskrepansies met literatuur waardes. Die verskille tussen die eksperimentele en literatuur data word geregverdig deur die verskille tussen die vloeistowwe, pakking en eksperimentele stelsels wat in die onderskeie studies gebruik is.

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Made available in DSpace on 2014-10-09T12:27:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:14Z (GMT). No. of bitstreams: 0 / Na década de 70 operou-se no IPEN/CNEN-SP uma instalação piloto para estudos do processamento de diferentes concentrados de tório obtidos do tratamento químico da monazita com intuito da obtenção de compostos de tório de pureza nuclear. Esta instalação passou a operar em escala industrial em 1985, gerando em torno de 25 toneladas de resíduo até meados de 2002, quando encerrou suas atividades. Este resíduo contendo tório e terras raras foi denominado Retoter (Resíduo de Tório e Terras Raras) e armazenado no galpão de Salvaguardas do IPEN. O presente trabalho estuda o tratamento deste resíduo, visando questões ambientais, radiológicas e tecnológicas. Estudaram-se dois processos cromatográficos para a separação do tório das terras raras. Um deles, a cromatografia de extração, onde o agente extrator fosfato de tri-n-butila foi suportado em resinas poliméricas Amberlite XAD16. O outro processo, estudado para fins comparativos, já que o material utilizado na cromatografia de extração é inédito no que diz respeito à separação do tório, foi a cromatografia de troca iônica utilizando resinas catiônicas fortes DOWEX 1-X8. Estudou-se, também, o processo cromatográfico de extração com o agente extrator DEHPA suportado em Amberlite XAD16 para o fracionamento, em grupos, dos elementos das terras raras. O tório foi separado com elevado grau de pureza para fins estratégicos e as terras raras recuperadas, livres de tório, foram testadas como catalisadores na reforma de etanol para a geração de hidrogênio, o qual é utilizado em células a combustível para a geração de energia elétrica. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientador: Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T01:42:32Z (GMT). No. of bitstreams: 1 AlvarezGomez_PabloAndres_M.pdf: 1373046 bytes, checksum: 138e327f31b722a5e684c4040df8aec9 (MD5) Previous issue date: 2011 / Resumo: Neste trabalho, simulações da etapa de fermentação para a produção de bioetanol foram realizadas utilizando o simulador Aspen Plus® com objetivo de realizar um estudo do processo fermentativo dentro de um cenário mais realista. A modelagem cinética foi realizada levando em conta os efeitos inibitórios da fermentação mediante a implementação de uma sub-rotina Fortran ao simulador. Além do mais, foram estudados diferentes arranjos operacionais de dornas de fermentação de uma unidade móvel para produção de bioetanol. Uma comparação com a simulação do processo de fermentação, utilizando equações estequiométricas também foi realizada. Os resultados mostram um maior desempenho em termos de rendimento para as simulações onde equações estequiométricas são utilizadas isto atribuído ao fato destas simulações desconsiderarem os efeitos inibitórios dos microrganismos fermentativos, o qual justifica a importância deste trabalho. Análises de sensibilidade com relação ao efeito da temperatura e conteúdo de substrato no mosto foram realizadas com o objetivo de avaliar o desempenho do modelo cinético. Comparações de diferentes arranjos operacionais de uma planta piloto móvel são também apresentadas: Batelada, contínua em serie, contínua em paralelo e BatCon. As simulações do processo batelada e contínuo usando unidades de operação do Aspen Plus (Rbatch e o Rcstr), mostraram que o modelo utilizado respondeu bem as variações de parâmetros, provando ser representativo para determinar as condições de operação de uma planta piloto ou industrial. Os arranjos operacionais simulados da planta da fermentação móvel apresentaram variações nos seus rendimentos, o processo em continuo presentaram os melhores rendimentos em comparação como os processos em batelada. O maior rendimento foi apresentado pelo processo contínuo em serie (98,96%), sendo o menor rendimento para o processo Batelada (93,39%) / Abstract: In this work, simulations of step fermentation for the bioethanol production were performed using the Aspen Plus simulator in order to making a study of the fermentation process in a more realistic scenario. The kinetic modeling was performed taking into account the inhibitory effects of fermentation with the implementation of a Fortran subroutine to the simulator. Furthermore, we studied different operational arrangements of fermentation vessels of a mobile unit for production of bioethanol. A comparison with the simulation of the fermentation process, using stoichiometric equations was also performed. The results show a better performance in terms of yield for the simulations where stoichiometric equations are used, attributed to the fact that these simulations disregard the inhibitory effects of fermentative microorganisms, which justifies the importance of this work. Sensitivity analysis regarding the effect of temperature and substrate content in the must, were performed with the objective to evaluate the performance of the kinetic model. Comparisons of different operational arrangements a mobile pilot plant is also presented: Batch, continuous series, parallel and continuous, and BatCon. The simulations of the process batch and continuous, using units operation Aspen Plus (Rbatch and Rcstr) showed that the model used responded well to the parameter variations, proving to be representative for conditions of operation of a pilot plant or industrial. The operational arrangements of simulated mobile fermentation plant showed variations in their yields, the continuous process presented the best returns as compared to batch processes. The highest yield was presented by the ongoing process in series (98.96%), the lowest yield for batch processes (93.39%) / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

The purpose of this research was to design, fabricate and test a 1 liter per minute pilot plant with a cascading sequence of continuously stirred tank reactors. The object of the research was to chemically decolorize selected reactive-dye bath concentrates resulting from exhaustive dyeing, and to remove metals and DOC using Fenton's Reagent or the reductive chemicals, thiourea dioxide and sodium hydrosulfite. For the Fenton's Reagent studies, ferrous sulfate was premixed with the dye waste concentrate before overflowing to the first reactor. A feedback control system based on color remaining in the discharge was used to regulate reactants added. Transmittance was measured at several wavelengths (590, 540, and 438 nm) and the American Dye Manufacturers Institute (ADMI) value calculated. The results demonstrated that ADMI measurements could not be made on dark solutions (over 3000 ADMI) in the pilot plant and, typically, one wavelength was used for control. DOC removal was used as a means of determining the biological activity in aerated reactors following color removal. The initial pilot plant studies were conducted using Navy 106 jet-dye waste. Reductive pretreatment with thiourea dioxide resulted in 92.2% color removal with color returning upon aeration for an overall color removal of 76.6%. Oxidative pretreatment with Fenton's chemistry resulted in 98.8% color removal with overall color removal after aerobic treatment at 96.8%. Dissolved Organic Carbon (DOC) removal in aerobic treatment improved with oxidative pretreatment relative to reductive pretreatment on Navy 106 jet-dye concentrate. On site operation of the pilot plant on other dye wastes showed color removals above 95% and DOC removals of 38% and 19% for an azo-based red dye waste concentrate and a copper-phthalocyanine-based dye, Ming Jade, respectively. The soluble copper concentration in the Ming Jade was decreased from 19.2 ppm to 4.5 ppm. This corresponded to a 3-fold increase in suspended solids from 0.575 g/L to 1.505 g/L. The results showed that continuous oxidative pretreatment with a 15-minute residence time was controllable and more effective than reductive treatment for color removal. Oxidative pretreatment also decreased the soluble copper concentration in a copper containing waste water, and did not hinder biological activity. / Master of Science