[pt] Uma preocupação significativa durante a produção de óleo e gás é a garantia de escoamento para evitar desperdício de tempo e dinheiro. Devido às mudanças nas condições durante a produção (como pressão e temperatura), principalmente na região do pré-sal brasileiro, a solubilidade dos componentes do petróleo bruto (óleo-gás-água) pode diminuir, resultando na formação de depósitos. A incrustação é geralmente causada por parafina, hidratos e sal inorgânico. Neste trabalho, foram desenvolvidos modelos utilizando estratégias de Aprendizado de Máquina para monitoramento da formação de incrustações inorgânicas e medição de parâmetros de processo associados com formas de remediação de obstruções de outras fontes. Primeiramente, foram criados modelos do processo de formação de incrustação de carbonato de cálcio na presença de monoetilenoglicol (inibidor de hidrato) usando a arquitetura de redes neurais feedfoward prever o pressão diferencial um e cinco instantes à frente, obtendo um R2 superior a 92,9 porcento para ambos os horizontes de predição. O segundo tópico explorado foi desenvolver modelos para determinação do pH em sistemas pressurizados (até 6,0 MPa) por meio de análise de imagens. Podendo ser aplicados no monitoramento de sistemas como Sistema Gerador de Nitrogênio, utilizado para remediar alguns problemas de incrustação, dado que sua cinética depende fortemente do pH do sistema. Foram criados modelos de classificação para o pH do sistema (2, 3, 4, 5, 6, 7, 8, 9, 10) usando Redes Neurais Convolucionais (CNN), Máquina de Vetor de Suporte e Árvores de Decisão. Além disso, modelos CNN foram construídos para predizer o pH na faixa de 2- 10. / [en] A significant concern during oil and gas production is flow assurance to avoid loss of time and money. Due to production conditions changes (such as pressure and temperature), especially in the Brazilian pre-salt region, the solubility of the components of the crude oil (oil-gas-water) can decrease, resulting in the formation of deposits. The fouling is usually caused by wax, gas hydrate, and inorganic salt (scale). In this work, models were developed using Machine Learning strategies for scale formation monitoring and measuring process parameters associated with remediation of obstruction from other sources. First, models for the calcium carbonate scaling formation process in the presence of monoethylene glycol (typical gas hydrate inhibitor) were created using feedforward neural network architecture to predict the differential pressure (deltaP) one and five steps ahead, obtaining an R2 higher than 92.9 percent for the training and test group for both the prediction horizon. The second approach explored was the development of models for determining the pH in atmospheric and pressurized systems (up to 6.0 MPa) using image analysis. These models could be applied to control and monitor the Nitrogen Generation System, which can be used for different flow assurance problems, and its kinetics strongly depend on the system s pH value. This step initially created classification models for the system pH (2, 3, 4, 5, 6, 7, 8, 9, 10) using the Convolution Neural Networks (CNN), Support Vector Machine, and decision tree architectures. Also, CNN models were built to predict the pH in the range of 2-10.

Shell and tube heat exchangers (STHEs) are the most common type of heat exchanger in preheat trains (PHT) of oil refineries and in chemical process plants. Most commercial design software tools for STHE assume uniform distribution over all tubes of a tube bundle. This leads to various challenges in the operation of the affected devices. Flow maldistribution reduces heat duty of STHE in many applications and supports fouling buildup in fluids that tend to particle, bio, and crystallization fouling (Verein Deutscher Ingenieure, ed., 2010, Heat Atlas, 2nd ed., VDI-Buch., Springer-Verlag). In this article, a fluid mechanics study about tube side flow distribution of crude oil and related hydrocarbons in two-pass PHT heat exchangers is described. It is shown that the amount of flow maldistribution varies significantly between the different STHE designs. Therefore, a parameter study was conducted to investigate reasons for maldistribution. For instance, the nozzles diameter, type, and orientation were identified as crucial parameters. In consequence, simple design suggestions for reducing tube side flow maldistribution are proposed.

Macromolecular biomaterials often require covalent crosslinking to achieve adequate stability and mechanical strength for their given application. However, the use of auxiliary chemicals may be associated with long-term toxicity in the body. Oppositely-charged polyelectrolytes (PEs) have the advantage that they can self-crosslink electrostatically and those derived from marine organisms are an inexpensive alternative to glycosaminoglycans present in the extracellular matrix of human tissues. A range of different combinations of PEs and preparation conditions have been reported in the literature. However, although there has been some work on complex formation between chitosan (CS) and carrageenan (CRG), much of the work undertaken has ignored the effect of pH on the consequent physicochemical properties of self-crosslinked polyelectrolyte complex (PEC) gels, films and scaffolds. Chitosan is a positively-charged polysaccharide with NH3+ side groups derived from shrimp shells and, carrageenan is a negatively-charged polysaccharide with OSO3- side groups derived from red seaweed. These abundant polysaccharides possess advantageous properties such as biodegradability and low toxicity. However, at present, there is no clear consensus on the cell binding properties of CS and CRG or CS-CRG PEC materials. The aim of this study was to explore the properties of crosslinker-free PEC gels, solvent-cast PEC films and freeze-dried PEC scaffolds based on CS and CRG precursors for medical applications. The objective was to characterise the effect of pH of the production conditions on the physicochemical and biological properties of CS-CRG PECs. Experimental work focused on the interaction between PEs, the composition of PECs, the rheological properties of PEC gels and the mechanical properties of PEC films and scaffolds. In addition, cell and protein attachment to the PEC films was assessed to determine their interactions in a biological environment. For biomedical applications, these materials should ideally be stable when produced such that they can be processed to form either a film or a scaffold and have mechanical properties comparable to those of collagenous soft tissues. FTIR was used to confirm PEC formation. Zeta potential measurements indicated that the PECs produced at pH 2-6 had a high strength of electrostatic interaction with the highest occurring at pH 4-5. This resulted in stronger intra-crosslinking in the PEC gels which led to the formation of higher yield, solid content, viscosity and fibre content in PEC gels. The weaker interaction at pH 7-12 resulted in higher levels of CS incorporated into the complex and the formation of inter-crosslinking through entanglements between PEC units. This resulted in the production of strong and stiff PEC films and scaffolds appropriate for soft tissue implants. The PECs prepared at pH 7.4 and 9 also exhibited low swelling and mass loss, which was thought to be due to the high CS content and entanglements. From the range of samples tested, the PECs produced at pH 7.4 appeared to show the optimum combination of yield, stability and homogeneity for soft tissue implants. Biological studies were performed on CS, CRG and PECs prepared at pH 3, 5, 7.4 and 9. All of the PE and PEC films were found to be non-cytotoxic. When the response of three different cell types and a high binding affinity protein (tropoelastin) was evaluated; it was found that the CS-CRG PEC films displayed anti-adhesive properties. Based on these experimental observations and previous studies, a mechanistic model of the anti-adhesive behaviour of PEC surfaces was proposed. It was therefore concluded that the CS-CRG PECs produced might be suitable for non-biofouling applications.

Modeling of heat transfer using Dymola. In this report a evaporator, economizer and superheater where modeled. The report describes how the models where modeled and what input was most suitable for a accurate model.

published_or_final_version / abstract / Environmental Management / Master / Master of Science in Environmental Management

A conventional membrane bioreactor (MBR) and two moving bed bioreactors coupled with ultrafiltration membrane filtration were operated for close to six months to investigate biological nutrient removal and potential fouling inducing parameter mitigation. Unique to one of the moving bed membrane bioreactors (MBMBR) was a newly designed media that incorporated a hydrodynamic exterior carrier with a highly porous interior packing. Preliminary investigation indicates that nitrogen compounds were superiorly removed in the two MBMBRs when compared with the MBR. This is a result of denitrification processes occurring in anoxic micro-zones found within the depths of the biofilm affixed to media. Fouling propensity was found to be increased by over four times in the MBMBR systems as compared to the MBR. Mixed liquor, permeate and filtrate analysis, membrane fibre examination and permeability tests indicated that colloidal organic carbon, as well as soluble microbial products were the dominant fouling inducing compounds. / Manuscript format / The Natural Sciences and Engineering Research Council of Canada

名古屋大学年代測定総合研究センターシンポジウム報告

The rapid increase in the demand on fresh water due the increase in the world population and scarcity of natural water puts more stress on the desalination industrial sector to install more desalination plants around the world. Among these desalination plants, multistage flash desalination process (MSF) is considered to be the most reliable technique of producing potable water from saline water. In recent years, however, the MSF process is confronting many problems to cut off the cost and increase its performance. Among these problems are the non-condensable gases (NCGs) and the accumulation of fouling which they work as heat insulation materials. As a result, the MSF pumps and the heat transfer equipment are overdesigned and consequently increase the capital cost and decrease the performance of the plants. Moreover, improved process control is a cost effective approach to energy conservation and increased process profitability. Thus, this study is motivated by the real absence of detailed kinetic fouling model and implementation of advance process control (APC). To accomplish the above tasks, commercial modelling tools can be utilized to model and simulate MSF process taking into account the NCGs and fouling effect, and optimum control strategy. In this research, gPROMS (general PROcess Modeling System) model builder has been used to develop the MSF process model. First, a dynamic mathematical model of MSF is developed based on the basic laws of mass balance, energy balance and heat transfer. Physical and thermodynamic properties of brine, distillate and water vapour are included to support the model. The model simulation results are validated against actual plant data published in the literature and good agreement with these data is obtained. Second, the design of venting system in MSF plant and the effect of NCGs on the overall heat transfer coefficient (OHTC) are studied. The release rate of NCGs is studied using Henry’s law and the locations of venting points are optimised. The results reveal that high concentration of NCGs heavily affects the OHTC. Furthermore, advance control strategy namely: generic model control (GMC) is designed and introduced to the MSF process to control and track the set points of the two most important variables in the MSF plant; namely the Top Brine Temperature (TBT) which is the output temperature of the brine heater and the Brine Level (BL) in the last stage. The results are compared to conventional Proportional Integral Derivative Controller (PID) and show that GMC controller provides better performance over conventional PID controller to handle a nonlinear system. In addition, a new control strategy called hybrid Fuzzy-GMC is developed and implemented to control the same aforementioned loops. Its results reveal that the new control outperforms the pure GMC in some areas. Finally, a dynamic fouling model is developed and incorporated into the MSF dynamic process model to predict fouling at high temperature and high velocity. The proposed dynamic model considers the attachment and removal mechanisms of calcium carbonate and magnesium hydroxide with more relaxation of the assumptions. Since the MSF plant stages work as a series of heat exchangers, there is a continuous change of temperature, heat flux and salinity of the seawater. The proposed model predicts the behaviour of fouling based on the physical and thermal conditions of every single stage of the plant.

Made available in DSpace on 2014-12-17T14:56:12Z (GMT). No. of bitstreams: 1 VictorLCMS_DISSERT.pdf: 2392559 bytes, checksum: f4276b98c00bcaaa7742d7ced860b2b7 (MD5) Previous issue date: 2013-04-19 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / A serious problem that affects an oil refinery s processing units is the deposition of solid particles or the fouling on the equipments. These residues are naturally present on the oil or are by-products of chemical reactions during its transport. A fouled heat exchanger loses its capacity to adequately heat the oil, needing to be shut down periodically for cleaning. Previous knowledge of the best period to shut down the exchanger may improve the energetic and production efficiency of the plant. In this work we develop a system to predict the fouling on a heat exchanger from the Potiguar Clara Camar?o Refinery, based on data collected in a partnership with Petrobras. Recurrent Neural Networks are used to predict the heat exchanger s flow in future time. This variable is the main indicator of fouling, because its value decreases gradually as the deposits on the tubes reduce their diameter. The prediction could be used to tell when the flow will have decreased under an acceptable value, indicating when the exchanger shutdown for cleaning will be needed / Um s?rio problema que afeta unidades de refino de petr?leo ? a deposi??o e incrusta??o de s?lidos nos equipamentos. Esses res?duos est?o naturalmente presentes no petr?leo ou s?o produtos de rea??es qu?micas durante o seu transporte. Um permutador de calor, quando sujo, perde sua capacidade de aquecer adequadamente o petr?leo, precisando, periodicamente, ser retirado de opera??o, para que possa ser realizada uma limpeza. Informa??es pr?vias do melhor per?odo para realizar as paradas podem melhorar a efici?ncia energ?tica e de produ??o da planta. Esse trabalho desenvolveu um sistema de predi??o da incrusta??o em um permutador da Refinaria Potiguar Clara Camar?o, com base em dados coletados em parceria com a Petrobras. Foram utilizadas redes neurais recorrentes que preveem a vaz?o no permutador em instantes futuros. Essa vari?vel ? o principal indicador da incrusta??o, pois seu valor diminui gradualmente ? medida que os dep?sitos nas paredes dos tubos reduzem seu di?metro. A predi??o pode ser usada para dizer quando a vaz?o ter? ca?do abaixo de um valor satisfat?rio, indicando quando ser? necess?rio retirar o equipamento de opera??o

Comme dans beaucoup de domaines, la sécurité dépend du développement de méthodes analytiques très sensibles et fiables pour pouvoir détecter des molécules dangereuses. C'est pourquoi il est important de développer des méthodes simples afin de diagnostiquer rapidement un composé dangereux dans notre environnement. Dans ce contexte, les techniques électrochimiques offrent une alternative intéressante puisqu'elles permettent d'atteindre de grandes sensibilités et une bonne sélectivité, elles sont peu coûteuses et facilement adaptables pour la création de dispositifs portables. Récemment, notre équipe a développé un nouveau concept basé sur de la voltammétrie par échantillonnage de courant sur un réseau d'électrodes (EASCV), lequel est compatible avec la miniaturisation. Ce système permet de renouveler la surface et la solution au voisinage de l'électrode pendant l'analyse. Le projet de cette thèse a été d'étendre l'application de cette technique à des méthodes électrochimiques utilisant une étape de préconcentration. Une première étude, appliquée à la détection du phénol, a permis de montrer que l'EASCV offre une solution intéressante pour diminuer les phénomènes de passivation ayant lieu pendant l'analyse. En effet, une étude expérimentale associée à une étude théorique a montré que si un temps d'échantillonnage court était appliqué, le phénomène de passivation pouvait être évité. Enfin, pour la première fois, il a été possible de coupler la voltammétrie par échantillonnage de courant à la redissolution anodique. Cette étude, appliquée à la détection du plomb, a permis de mettre en place une courbe d'étalonnage et d'obtenir une intensité élevée de courant, 300 fois plus importante qu'avec les techniques classiques de redissolution anodique. Les premiers essais pour adapter ce nouveau concept aux méthodes pulsés se sont également montrés très encourageants. Afin d'améliorer la sensibilité et la sélectivité du capteur, le réseau d'électrodes a été fonctionnalisé. La modification dépend de la nature de l'espèce cible. Ainsi des polymères à empreintes moléculaires (pour des molécules comme la mélamine) ou des ligands (pour des ions comme le plomb) ont été testés. Dans les deux cas, une méthode d'électrogreffage a été mise au point pour fonctionnaliser la surface. Les premiers résultats obtenus sont encourageants puisqu'une courbe courant-potentiel a pu être tracée montrant une sensibilité 10 fois plus grande pour le plomb que celle obtenue avec une préconcentration par électrodépôt. / As in many fields, safety is primarily based on the development of reliable and highly sensitive analytical methods to detect hazardous molecules. Therefore there is a need for developing simple methods for the diagnosis of harmful molecules in our environment. In this context, electrochemical detection systems seems very promising because they are highly sensitive, require short analysis time, are easy to implement and economic to fabricate. Moreover, our team has recently developed a new concept of device based on sampled-current voltammetry performed on an electrode array (EASCV) which is compatible with miniaturization and portability. The system allows the renewal of the electrode surface and of the analytical solution during the analysis. The present project addresses these issues and aims to extend it to methods involving a preconcentration step. A first study, for the detection of phenol, showed that EASCV offers a versatile solution to decrease fouling effect during the analysis. Indeed experimental and theoretical studies show that the renewable of electrode surface and of the solution in the vicinity of the electrode associated with the use of a short sampled time can avoid electrode fouling. For the first time, it was possible to combine sampled-current voltammetry with anodic stripping voltammetry. In this study, we were able to create a calibration curve, for the detection of lead, and we obtained current intensities 300 times higher than with usual linear stripping voltammetry.First attempts to adapt this new concept to pulse methods were promising.. To increase the sensitivity and selectivity of the sensor, the electrode array is chemically modified. The nature of this modification depends on the nature of the analyte. Thus, molecular imprinted polymer (for molecules) or macrocyclic ligands (for ions) are tested In both cases, an electrografting method is achieved to functionalize the surface. The first results are promising since a current-potential curve is obtained with a sensibility ten times higher than with a preconcentration by electrodeposition.