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 (Ph.D.)--Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

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. / <p>QC 20140306</p>

Os riscos de poluição ao meio ambiente envolvendo petróleo envolvem, não só o seu transporte, como também seu refino. O prejuízo causado por um derramamento de petróleo vai além de danos à fauna e flora, pois envolvem também questões sociais. A emissão de óxidos de enxofre, denominadas SOx, durante o refino de petróleo através do craqueamento catalítico em leito fluidizado (FCC) também é uma das preocupações ambientais, já que esses óxidos estão relacionados com o a formação de chuva ácida e problemas respiratórios. Os hidrocarbonetos provenientes de um derramamento podem ser degradados em produtos menos agressivos ao meio ambiente, por oxidação química, por exemplo. Já as emissões de enxofre na unidade de FCC podem ser minimizadas por diversos processos, como por exemplo, o uso de aditivos nas unidades de FCC. Nesse trabalho óxidos de manganês dos tipos OMS-1 e OMS-2 foram sintetizados em presença e ausência de biomassa e óxidos OMS-2 foram dopados com os metais cobre, vanádio e ferro. Possíveis alterações em suas propriedades, suas atividades catalíticas em oxidação de hidrocarbonetos e em testes de captura de enxofre em condições de temperatura similares à unidade de FCC foram investigadas. Constatou-se uma diminuição na área superficial, tamanho e volume de poros nos óxidos sintetizados em presença de biomassa, através de uma análise de adsorção e dessorção de N2 (ASAP), porém seus difratogramas em uma análise de difração de raio X de pó (DRX) revelaram a obtenção de estruturas do criptomelano em todos os OMS-2. Os óxidos OMS-2 testados na oxidação do cicloexano, não sofreram modificações em sua estrutura após seu uso como catalisador, mas a presença da biomassa na síntese não aumentou sua atividade catalítica. Nos testes DeSOx, o óxido dopado com ferro apresentou o melhor desempenho e testes em ciclos mostraram ser possível sua reutilização / The risk of pollution to the environment involving oil involve not only the transport, as well as its refining. The damage caused by an oil spill goes beyond damage to fauna and flora, they also involve social issues. The emission of sulfur oxides, SOx called during the refining of oil through the fluidized catalytic cracking (FCC) is also an environmental concern, since these oxides are related to the the formation of acid rain and respiratory problems. The hydrocarbons from a spill can be degraded into less harmful products for the environment by chemical oxidation, for example. Since sulfur emissions in the FCC unit can be minimized by various methods, for example, the use of additives in FCC units. In this work manganese oxides types of OMS-1 and OMS-2 are synthesized in the presence and absence of biomass and OMS-2 oxide was doped with the metals copper, vanadium and iron. Possible changes in their properties, their catalytic activities in the oxidation of hydrocarbons and sulfur capture in conditions similar to the FCC unit were investigated temperature tests. Found a decrease in the surface, size and volume of pores in the oxides synthesized in the presence of biomass area, through an analysis of N2 adsorption and desorption (ASAP), but their diffraction patterns on an analysis of X-ray diffraction powder (XRD) revealed the structures of obtaining criptomelano in all OMS-2. The OMS-2 oxides tested in the oxidation of cyclohexane, have not changed in its structure following its use as a catalyst, but the presence of biomass synthesis did not increase its catalytic activity. In Desox tests, the iron oxide doped showed the best performance and testing cycles proved possible reuse

Os riscos de poluição ao meio ambiente envolvendo petróleo envolvem, não só o seu transporte, como também seu refino. O prejuízo causado por um derramamento de petróleo vai além de danos à fauna e flora, pois envolvem também questões sociais. A emissão de óxidos de enxofre, denominadas SOx, durante o refino de petróleo através do craqueamento catalítico em leito fluidizado (FCC) também é uma das preocupações ambientais, já que esses óxidos estão relacionados com o a formação de chuva ácida e problemas respiratórios. Os hidrocarbonetos provenientes de um derramamento podem ser degradados em produtos menos agressivos ao meio ambiente, por oxidação química, por exemplo. Já as emissões de enxofre na unidade de FCC podem ser minimizadas por diversos processos, como por exemplo, o uso de aditivos nas unidades de FCC. Nesse trabalho óxidos de manganês dos tipos OMS-1 e OMS-2 foram sintetizados em presença e ausência de biomassa e óxidos OMS-2 foram dopados com os metais cobre, vanádio e ferro. Possíveis alterações em suas propriedades, suas atividades catalíticas em oxidação de hidrocarbonetos e em testes de captura de enxofre em condições de temperatura similares à unidade de FCC foram investigadas. Constatou-se uma diminuição na área superficial, tamanho e volume de poros nos óxidos sintetizados em presença de biomassa, através de uma análise de adsorção e dessorção de N2 (ASAP), porém seus difratogramas em uma análise de difração de raio X de pó (DRX) revelaram a obtenção de estruturas do criptomelano em todos os OMS-2. Os óxidos OMS-2 testados na oxidação do cicloexano, não sofreram modificações em sua estrutura após seu uso como catalisador, mas a presença da biomassa na síntese não aumentou sua atividade catalítica. Nos testes DeSOx, o óxido dopado com ferro apresentou o melhor desempenho e testes em ciclos mostraram ser possível sua reutilização / The risk of pollution to the environment involving oil involve not only the transport, as well as its refining. The damage caused by an oil spill goes beyond damage to fauna and flora, they also involve social issues. The emission of sulfur oxides, SOx called during the refining of oil through the fluidized catalytic cracking (FCC) is also an environmental concern, since these oxides are related to the the formation of acid rain and respiratory problems. The hydrocarbons from a spill can be degraded into less harmful products for the environment by chemical oxidation, for example. Since sulfur emissions in the FCC unit can be minimized by various methods, for example, the use of additives in FCC units. In this work manganese oxides types of OMS-1 and OMS-2 are synthesized in the presence and absence of biomass and OMS-2 oxide was doped with the metals copper, vanadium and iron. Possible changes in their properties, their catalytic activities in the oxidation of hydrocarbons and sulfur capture in conditions similar to the FCC unit were investigated temperature tests. Found a decrease in the surface, size and volume of pores in the oxides synthesized in the presence of biomass area, through an analysis of N2 adsorption and desorption (ASAP), but their diffraction patterns on an analysis of X-ray diffraction powder (XRD) revealed the structures of obtaining criptomelano in all OMS-2. The OMS-2 oxides tested in the oxidation of cyclohexane, have not changed in its structure following its use as a catalyst, but the presence of biomass synthesis did not increase its catalytic activity. In Desox tests, the iron oxide doped showed the best performance and testing cycles proved possible reuse

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-06-05T18:05:00Z No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-05T18:19:12Z (GMT) No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-05T18:19:18Z (GMT) No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) / Made available in DSpace on 2017-06-05T18:24:29Z (GMT). No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) Previous issue date: 2017-01-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The fluid catalytic cracking (FCC) is an important process in oil industry, since it converts heavier fractions in lighter ones, which are more valuable. The catalyst particles (typically m) are deactivated during the reacting process and need to be regenerated before returning to the reactor. Temperature is a key factor that promotes coke formation and deactivation inside the reactor. As a consequence, it is necessary to cool down the solid catalyst particles before returning them to the reactor. The cooling system is usually outside the regenerator in a specific designed heat exchanger, that uses water as cold fluid. The catalyst cooler was not much studied before and many contributions can be made for improvements and intensification. The goal of this work was to contribute with this topic, using Computational Fluid Dynamics (CFD) to evaluate the gas-solid flow behavior in characteristic geometries of the catalyst cooler. Commercial package Fluent by ANSYS v14.5 was used during simulation and Eulerian model was applied for the solid phase. The volume fraction phase for the solid phase, solid and gas velocities were evaluated and described. The results were compared in terms of gas-solids flow in different geometries and showed a hydrodynamic explanation different from that currently used by the authors to justify the intensification of thermal exchange in this type of equipment. In short, longer solid-wall contact time will be primarily responsible for efficient heat transfer. / O craqueamento catalítico fluidizado é um processo amplamente utilizado no campo do refino de petróleo. Na unidade de craqueamento, frações pesadas são transformadas em outras mais leves e com maior valor de mercado (gasolina, diesel, naftas). Após o craqueamento, o catalisador é regenerado e retorna ao reator. A temperatura do catalisador é um parâmetro que possui forte influência sobre o processo. O resfriamento de catalisador é feito em unidades externas a fim de controlar a temperatura de entrada do catalisador no reator. O funcionamento deste sistema ainda foi pouco explorado e o objetivo deste trabalho foi o de simular o escoamento gás-sólido em geometrias características de colunas para resfriamento de catalisador com diferentes condições de operação, assim tentando contribuir com o conhecimento sobre este processo. Técnicas de Fluidodinâmica Computacional foram usadas para a simulação de diferentes geometrias com o programa comercial FLUENT do pacote ANSYS v14.5. As distribuições fração volumétrica dos sólidos e de velocidades do gás e fase particulada foram analisados como parâmetros de interesse hidrodinâmico. Os resultados foram comparados em termos de escoamento gás-sólido em diferentes geometrias e mostraram uma explicação hidrodinâmica diferente da atualmente utilizada pelos autores para justificar a intensificação de troca térmica em este tipo de equipamentos. Em suma, maior contato sólido-parede seria o principal responsável pela transferência eficiente de calor.

Orientador: Milton Mori / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-10T23:15:40Z (GMT). No. of bitstreams: 1 Rosa_LeonardoMachadoda_D.pdf: 1367270 bytes, checksum: 1819e68c66a949c1c8fae024725df552 (MD5) Previous issue date: 2008 / Resumo: A aplicação de Fluidodinâmica Computacional (CFD) em operações industriais vem aumentando sensivelmente, em razão desta auxiliar no projeto de novos equipamentos, bem como a otimização dos já existentes. O presente trabalho apresenta uma série de simulações tridimensionais, bifásicas e adiabáticas, utilizando-se o modelo de dois-fluidos para o cálculo do escoamento gás-sólido em risers de diferentes tamanhos ¿ um com as dimensões de 10m de altura e 76mm de diâmetro interno, e outro com 18m de altura e 50mm de diâmetro interno. Utilizou-se o modelo k-epsilon para tratar a fase gasosa como turbulenta. Foram considerados os modelos cinéticos de 4 lumps e 10 lumps para o cálculo das taxas de craqueamento catalítico presentes no reator. Dados experimentais para comparação do escoamento foram obtidos em literatura, e os resultados obtidos mostram que, para a correta predição dos fenômenos presentes no interior de um riser, deve-se levar em consideração também as reações de craqueamento, visto que a alteração da composição química da fase gasosa interfere diretamente no comportamento dinâmico do escoamento / Abstract: The application of Computational Fluid Dynamics (CFD) in industrial operations has been increased not only in the project of new equipments but also in the optimization of the existing ones. The present work shows a set of tridimensional two-phase and adiabatic conditions, using the two-fluids model for the calculation of gas-solids flow in a high-flux risers of two different geometries, one with 10m of height and 76mm of internal diameter, and the second with 18m of height and 50mm of internal diameter. The k-epsilon model was applied to consider the influence of turbulence over the gas phase. The four-lump and ten-lump schemes kinetic models were used to predict the catalytic cracking reactions in the two different reactors. The riser with 10m of height and 76 mm of internal diameter had two entrances, one for particles inlet and one for the organic materials. The size of mesh for this case was 584.000 control volumes. The second riser studied with geometry of 18m of height and 50mm of internal iameter had one entrance for vapor, one for organic materials, and a third for particles inlet. The mesh generated over this geometry was considered 650.000 control volumes. The numerical results of gas-solids dispersion flow in a high-flux were compared with the xperimental data from the work of P¨arssinen and Zhu (2001), the four lump scheme for he mass concentration of chemical species was compared with the work of (ALI et al., 997), and the ten lump scheme was compares with the work of NAYAK et al. (2005). The catalytic cracking reactions models show an important role in the prediction of all henomena present in the reactor. The simulated results show that the kinetics models are important not only because of the variation of the gas phase and the temperature profiles inside the reactor but also because these parameters interfere directly in the dynamic behavior of the gas-solid flows / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Orientador: Milton Mori / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-26T06:44:29Z (GMT). No. of bitstreams: 1 AlvarezCastro_HelverCrispiniano_D.pdf: 5280150 bytes, checksum: 96fb29e2849d11c06890186cb8af2f51 (MD5) Previous issue date: 2014 / Resumo: Conversão de matéria-prima e rendimento são estudados através de um modelo 3D que simula o principal reator do processo de craqueamento catalítico fluidizado (FCC). Fluidodinâmica computacional (CFD) é usada como técnica com abordagem Euleriana-Euleriana para prever o comportamento do riser da FCC. O modelo considera 12 grupos com desativação do catalisador dada por coque e envenenamento por nitritos alcalinas e adsorção aromático policíclico para estimar o comportamento cinético, o qual partindo de uma determinada matéria prima, se craquea a diversos produtos. Composições diferentes para matérias-primas foram consideradas. Para validação o modelo foi comparado com dados experimentais em condições de operação industrial. O modelo é capaz de representar com precisão a geração de produtos para as diferentes condições de operação consideradas. Todas as condições consideradas foram resolvidos usando o solver Ansys CFX 14.0. As diferentes variáveis do processo de operação e efeitos hidrodinâmicos do riser industrial de craqueamento catalítico fluidizado (FCC) foram avaliadas. As previsões do modelo são apresentados e comparadas; conversão e produtos são apresentados. Recomendações para criar condições para obter maior rendimento do produto no processo industrial foram dadas / Abstract: Feedstock conversion and yield products are studied through a 3D model simulating the main reactor of the fluid catalytic cracking (FCC) process. Computational Fluid Dynamic (CFD) is used with Eulerian-Eulerian approach to predict the fluid catalytic cracking behavior. The model considers 12 lumps with catalyst deactivation by coke and poisoning by alkaline nitrides and polycyclic aromatic adsorption to estimate the kinetic behavior which, starting from a given feedstock, produces several cracking products. Different feedstock compositions are considered. The model is compared with sampling data at industrial operation conditions. The simulation model is able to represent accurately the products behavior for the different operating conditions considered. All the conditions considered were solved using a solver Ansys CFX 14.0. The different operation process variables and hydrodynamic effects of the industrial riser of a fluid catalytic cracking (FCC) are evaluated. Predictions from the model are shown and comparison with experimental conversion and yields products are presented; recommendations are drawn to establish the conditions to obtain higher product yields in the industrial process / Doutorado / Engenharia de Processos / Doutor em Engenharia Química

Orientador: Milton Mori / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T06:39:27Z (GMT). No. of bitstreams: 1 GonzalezSilva_German_D.pdf: 4427269 bytes, checksum: bb45c122c3faad0613f060ad4cbd3b61 (MD5) Previous issue date: 2012 / Resumo: O objetivo principal desta tese é propor uma metodologia para aplicar simulação de grandes escalas (LES) em uma unidade de craqueamento catalítico industrial. Para atingir este objetivo, iniciou-se propondo uma metodologia para a construção da malha, sendo uma malha quase-uniforme. As malhas propostas foram implementadas para minimizar o esforço computacional e procedimento para a refinação uniforme no domínio do sistema. Inicialmente, foi estudada a fluidodinâmica de um leito fluidizado gás-sólido na escala de laboratório sem reação química, utilizando Simulação de Grandes Escalas. Com base nos resultados numéricos obtidos a partir de resultados da escala de laboratório foi aplicado o modelo cinético de 4 lump em uma simulação CFD tridimensional para um reator industrial FCC, utilizando LES para a fase gasosa, e considerando o catalisador como uma fase contínua (Euleriana). Os pacotes de simulação utilizados foram Ansys ICEM versão 13 para a construção da malha e Ansys CFX versão 13 para o pós-processamento dos resultados. No pós-processamento dos resultados foi proposta uma metodologia para determinar as médias azimutais das variáveis em planos perpendiculares ao escoamento e finalmente foram validadas as simulações com dados reportados na literatura. As principais conclusões do trabalho foram que foi possível diminuir o tamanho da malha e o tempo de processamento. Notou-se também que, ao usar malhas com discretização quase-uniforme não foi necessário fazer um refinamento de malha elevado, nem refinar perto da parede para o sistema gás-sólido / Abstract: The main objective of this thesis is to propose a methodology in how to apply Large Eddy Simulation (LES) on a unit of catalytic cracking. In order to achieve this, it was proposed an alternative way of constructing the computational mesh, by using quasi-uniform meshes. The proposed meshes were implemented to minimize the computational effort and procedure for refining them in the entire domain of the system. Initially it was studied the fluid dynamics of a lab scale gas-solid system without chemical reaction, using Large Eddy Simulation. Based on the numerical results obtained from lab scale results it was implemented the 4 lump kinetic model in a three dimensional CFD simulation of an FCC industrial reactor, using LES for the gas phase and considering the catalyst as a continuous phase (Eulerian). The simulation packages used were Ansys ICEM, version 13 for mesh construction and Ansys CFX 13 for computation and post-processing of the results. In the data post-processing it was proposed a methodology for calculating average values of fluctuating variables between two circular sections in the azimuthal direction. The results were compared with data reported in literature. The main conclusions of the results showed that it was possible to decrease the mesh size and the computational time. It was also noticed that by using quasi-uniform discretization it was not necessary to make a high mesh refinement near the wall for a gas-solid system / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Orientadores: Rubens Maciel Filho, Delba Nisi Cosme Melo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T11:54:20Z (GMT). No. of bitstreams: 1 CuadrosBohorquez_JoseFernando_D.pdf: 6686167 bytes, checksum: 1899259fbe648f651c06a5f9ca3e2c29 (MD5) Previous issue date: 2012 / Resumo: Esta pesquisa teve por finalidade o desenvolvimento de uma metodologia de otimização em duas camadas. A otimização preliminar foi baseada na técnica de planejamento de experimentos junto com a metodologia por superfície de resposta com a finalidade de identificar uma possível região de busca do ponto de operação ótimo, o qual foi obtido através da implementação de métodos híbridos de otimização desenvolvidos mediante associação do modelo determinístico de otimização por programação quadrática sucessiva (SQP) com a técnica dos algoritmos genéticos (GA) no modelo do processo de craqueamento catalítico fluidizado- FCC. Este processo é caracterizado por ser um sistema heterogêneo e não isotérmico, cuja modelagem detalhada engloba as equações de balanço de massa e energia das partículas do catalisador, como também para a fase líquida e gasosa, sendo um dos casos de estudo para a aplicação da metodologia de otimização desenvolvida. Como caso de estudo principal foi considerado o modelo do conversor do processo de FCC desenvolvido por Moro e Odloak (1995). Mediante a metodologia de otimização do processo baseado no uso do modelo determinístico da planta, foram definidas estratégias e políticas operacionais para a operação da unidade de FCC em estudo. Procurou-se alto nível de desempenho e segurança operacional, através da integração das etapas de operação, otimização e controle no contexto de otimização em tempo real do processo. As otimizações foram divididas em quatro etapas: 1) Análises preliminares dos fatores e das variáveis de resposta do modelo do conversor foram realizadas usando a técnica de planejamento de experimentos, com o objetivo de compreender a interação entre elas, assim como obter modelos simplificados das variáveis de resposta. A geração dos modelos simplificados é devido à necessidade de ganho no tempo computacional permitindo o conhecimento prévio da região de otimização já que em casos industriais pode não ser possível representar adequadamente o processo por modelos determinísticos; 2) Otimização usando algoritmos genéticos implementados no modelo simplificado da conversão, e no modelo determinístico com e sem restrições; 3) Otimização considerando o método de otimização SQP implementado no modelo simplificado da conversão e no modelo determinístico com restrições; e 4) otimização multi-objetivo do conversor usando x a técnica dos algoritmos genéticos, com o objetivo de maximizar a conversão, assim como a minimização da vazão dos gases de combustão, especificamente o monóxido de carbono (CO). Das otimizações foram obtidos ganhos em torno de 8% na conversão quando comparado com os valores de conversão sem otimização. Finalmente, foi realizada a integração do modelo do processo, com a otimização e o controle, dando como resultado a otimização em tempo real do conversor de FCC. A variável de otimização foi a conversão e, através da implementação do controle por matriz dinâmica com restrições (QDMC), aplicando a metodologia de controle inferencial. As variáveis escolhidas como variável controlada foi a temperatura de reação e como variável manipulada foi a temperatura da alimentação, com perturbações na vazão de alimentação do ar de regeneração. Valores de conversão da ordem de 88% foram atingidos para o esquema de otimização em tempo real, o método de otimização por algoritmo genético apresentou um desempenho satisfatório, com tempos e cargas computacionais razoáveis para implementação desta metodologia, em nível industrial / Abstract: The purpose of this research was the develop of an optimization methodology. Experimental design technique along with a hybrid optimization methodology obtained by association of sequential quadratic programming (SQP) with genetic algorithms (GA), were implemented in the model of a Fluid Catalytic Cracking process (FCC) developed by Moro and Odloak (1995). This process is described for a heterogeneous, non isothermal system, in which a detailed modeling comprises mass and energy balance equations for catalyst particles, liquid and gaseous phases that makes this process model, a case study for implementing the optimization methodology developed. The process optimization methodology developed; along with the deterministic model of the plant were applied to define operational strategies and policies for the operation of the FCC unit studied aiming to obtain high performance and operational safety, through the integration of control, operation and optimization stages in the context of real-time optimization (RTO) process. Optimizations were divided into four stages: 1) Preliminary analysis of factors and response variables of converter modeling were performed using experimental design technique aiming to understand the factors and response variables interaction, as well as to obtain response variables simplified models to be used as objective function in optimization stages, 2) a optimization using genetic algorithms was implemented in the simplified conversion model, in the deterministic modeling and the deterministic model considering factors restrictions, 3) a optimization considering a local search methodology like sequential quadratic programming (SPQ) was implemented in the simplified model of process conversion and also it was consided the deterministic model with restrictions. As initial estimative, the optimum factor values obtained with genetic algorithms were considered as well as two random points in the search space, and 4) a multi objective optimization considering genetic algorithms technique in order to maximize conversion and minimize combustion gases emissions, specifically carbon monoxide was developed. Applying this optimization methodology was obtained increments of around 8% in the feed conversion when compared with conversion values without optimization. xii Finally, it was developed the integration of optimization, control and process modeling giving as result the real time optimization (RTO) of FCC converter. The variable maximized by genetic algorithms was the feed conversion and the control technique implemented was based on the matrix named (QDMC) in conjunction with inferential control methodology. It was considered as controlled variable the reaction temperature adjusting the feed temperature (manipulated variable), for disturbances in the feed flow of the regeneration air. Feed conversion in the order of 88% were achieved for the real time optimization scheme considered, in which, the genetic algorithm showed an excellent performance in reasonable computational times and computational loads for implementation at industrial level / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química