Dissertations / Theses on the topic 'Gas/Oil Separation'

Two main topics are treated in this doctoral thesis from a theoretical and computational point of view: the gas capture and separation from post-combustion flue gases, and the enhanced oil recovery from oil reservoirs. The first topic evaluates the separation of CO2 using three different materials. First, several zeolites from the Faujasite family are studied with a combination of Density Functional Theory (DFT) and Monte Carlo methods. The former is employed to understand the driving mechanisms of adsorption, whereas the latter served to assess the separation of CO2 from a flue gas formed by a ternary mixture of CO2, N2 and O2. Second, the adsorption of CO2, N2 and SO2 into Mg-MOF-74 obtained through DFT calculations is presented to determine the most fundamental gas/MOF interactions. The results are then coupled to a Langmuir isotherm model to derive the macroscopic adsorption isotherms of the three gases in Mg-MOF-74. Finally, the absorption of CO2 and SO2 into three different phosphonium-based Ionic Liquids (ILs) is addressed by using the soft-SAFT equation of state and the COSMO-RS model. From the calculated adsorption/absorption isotherms several properties are obtained, such as the purity in the recovered gas, the working capacity of the materials and their selectivity to capture CO2 in the presence of other contaminant species. The main results obtained from this part of the thesis reveal that the cations of microporous materials are very strong sites of absorption for polar gases (i.e., the Na+ cations in Faujasites or the Mg2+ cations in Mg-MOF-74). This feature makes them very good candidates for CO2 capture, but they can be easily poisoned by other polar gases such as SO2. For this reason, it is highly recommended to desulphurize the flue gas before using any of these adsorbents. Similarly, ILs have higher affinity for SO2 than for CO2. However, the gas/IL interactions are significantly weaker, so they do not become poisoned by SO2. This fact implies that SO2 can be captured and separated from the flue gas by using a phosphonium-based IL. The second topic describes via Molecular Dynamics simulations the interactions of several model oils with different rocks and brines. The obtained insight can be applied in better understanding the interactions of the species present at oil reservoirs, with direct application in enhanced oil recovery processes. To that end, two wettability indicators are monitored to determine the potential recovery of the model oils. First, the oil/water interfacial tension (IFT) under different conditions of temperature, pressure and salinity (i.e., from pure water to 2.0 mol/kg of NaCl or CaCl2). And second, the oil/water/rock contact angle (CA) on calcite (10-14) and kaolinite (001) also as a function of salinity (i.e., from pure water to 2.0 mol/kg of NaCl or CaCl2). The different model oils are built with molecules of different chemical nature representing the Saturate/Aromatic/Resin/Asphaltene (SARA) fractionation model. In a final stage of the doctoral thesis the effect of non-ionic surfactants at the oil/brine IFT is also included. The main results obtained show that the most polar components of oil migrate to the oil/water interface and reduce the IFT. However, the same compounds feel attracted to the rock, who increase the CA and hamper the oil recovery. Some of these interactions are affected by the presence of salt. Specifically, if a water layer is formed between the oil and the rock in a reservoir, electrolytes can diffuse into it and attract the polar components of oil, ultimately increasing the CA. Finally, cations can be attracted to the oil/water interface due to salt/surfactant interactions. Both species interact synergistically to modify their orientation/distribution at the interface and reduce the oil/water IFT.
En aquesta tesi doctoral s’han tractat dos temes principals des d’una perspectiva teòrica i computacional: la captura i separació de gasos de post-combustió, i la recuperació millorada de petroli. El primer tema avalua la separació de CO2 utilitzant tres materials diferents. Primer, s’han estudiat diverses zeolites de la família de les Faujasites amb una combinació de teoria del funcional de la densitat (TFD) i mètodes Monte Carlo per entendre els mecanismes d’adsorció separació de CO2 d’una mescla ternària que conté CO2, N2 i O2. Seguidament, s’ha presentat un estudi TFD d’adsorció de CO2, N2 i SO2 en Mg-MOF-74 per determinar les interaccions fonamentals del MOF amb cada gas. Aquesta informació s’ha acoblat a un model d’isoterma de Langmuir per tal de derivar les isotermes d’adsorció macroscòpiques dels tres gasos en Mg-MOF-74. Finalment, s’ha analitzat l’absorció de CO2 i SO2 en tres Líquids Iònics (LIs) basats en fosfoni mitjançant l’equació d’estat soft-SAFT i el model COSMO-RS. D’altra banda, el segon tema descriu les interaccions de diferents models de petroli amb roques i salmorres, via simulacions de Dinàmica Molecular. El coneixement adquirit en aquesta part de la tesi doctoral es pot aplicar directament a la recuperació millorada de petroli i per entendre millor les interaccions de les espècies presents als pous. Amb aquesta finalitat, s’han controlat dos indicadors de la mullabilitat per determinar la recuperació potencial d’aquests models de petroli. Primer la tensió interfacial (TIF) oli/aigua sota diferents condicions de temperatura, pressió i salinitat (des d’aigua pura a 2.0 mol/kg de NaCl o CaCl2). I segon, l’angle de contacte oli/aigua/roca en calcita (10-14) i caolinita (001) en funció de la salinitat (des d’aigua pura a 2.0 mol/kg de NaCl o CaCl2). Els diferents models de petroli s’han construït amb molècules de diferent naturalesa química representant el model de fraccionament Saturat/Aromàtic/Resina/Asfaltè (SARA). En una etapa final de la tesi doctoral s’ha inclòs l’efecte en la TIF induïda pels surfactants no-iònics a la interfase oli/salmorra.

As reserves of conventional crude oil are depleted, there is a growing need to develop unconventional oils such as heavy oil and bitumen from oil sands. In terms of recoverable oil, Canadian oil sands are considered to be the second largest oil reserves in the world. However, the upgrading of bitumen from oil sands to synthetic crude oil (SCO) requires nearly ten times more hydrogen (H₂) than the conventional crude oils. The current H₂ demand for oil sands operations is met mostly by steam reforming of natural gas. With the future expansion of oil sands operations, the demand of H₂ for oil sand operations is likely to quadruple in the next decade. As natural gas reforming involves significant carbon dioxide (CO₂) emissions, this sector is likely to be one of the largest emitters of CO₂ in Canada.

In the current H₂ plants, CO₂ emissions originate from two sources, the combustion flue gases from the steam reformer furnace and the off-gas from the process (steam reforming and water-gas shift) reactions. The objective of this study is to develop a process that captures CO₂ at minimum energy penalty in typical H₂ plants.

The approach is to look at the best operating conditions when considering the H₂ and steam production, CO₂ production and external fuel requirements. The simulation in this study incorporates the kinetics of the steam methane reforming (SMR) and the water gas shift (WGS) reactions. It also includes the integration of CO₂ capture technologies to typical H₂ plants using pressure swing adsorption (PSA) to purify the H₂ product. These typical H₂ plants are the world standard of producing H₂ and are then considered as the base case for this study. The base case is modified to account for the implementation of CO₂ capture technologies. Two capture schemes are tested in this study. The first process scheme is the integration of a monoethanolamine (MEA) CO₂ scrubbing process. The other scheme is the introduction of a cardo polyimide hollow fibre membrane capture process. Both schemes are designed to capture 80% of the CO₂ from the H₂ process at a purity of 98%.

The simulation results show that the H₂ plant with the integration of CO₂ capture has to be operated at the lowest steam to carbon (S/C) ratio, highest inlet temperature of the SMR and lowest inlet temperatures for the WGS converters to attain lowest energy penalty. H₂ plant with membrane separation technology requires higher electricity requirement. However, it produces better quality of steam than the H₂ plant with MEA-CO₂ capture process which is used to supply the electricity requirement of the process. Fuel (highvale coal) is burned to supply the additional electricity requirement. The membrane based H₂ plant requires higher additional electricity requirement for most of the operating conditions tested. However, it requires comparable energy penalty than the H₂ plant with MEA-CO₂ capture process when operated at the lowest energy operating conditions at 80% CO₂ recovery.

This thesis also investigates the sensitivity of the energy penalty as function of the percent CO₂ recovery. The break-even point is determined at a certain amount of CO₂ recovery where the amount of energy produced is equal to the amount of energy required. This point, where no additional energy is required, is approximately 73% CO₂ recovery for the MEA based capture plant and 57% CO₂ recovery for the membrane based capture plant.

The amount of CO₂ emissions at various CO₂ recoveries using the best operating conditions is also presented. The results show that MEA plant has comparable CO₂ emissions to that of the membrane plant at 80% CO₂ recovery. MEA plant is more attractive than membrane plant at lower CO₂ recoveries.

Serious games and its related fields have lately received a lot of interest due to their potential for training and education. Serious games can be defined as (digital) games that are used for reasons other than entertainment. Gamification can be related to serious games and can be defined as the process of game-thinking and game mechanics to engage users and solve problems.The initiator of this project was ABB. ABB delivers a process control system used to control the processes of an oil production facility. One of these processes is separating oil and gas from water. A simulator of this separation process was developed and then implemented into HawkEye, a prototype of the existing process control system. We have worked with ABB to gamify the implemented separation process using different game mechanics to discover whether gamification can be used to improve a process operator's skills, understanding, and motivation. In a process control system, the process at hand has the highest priority due to its severity, which means that the gamified elements have to be subtle.The implemented separation process was tested on two groups consisting of ten people each, most of them students. The two groups carried out the separation process twice, one time without the gamified elements and one time with the gamified elements. The difference between the two groups was in which order they did the separation process.After the experiment, data was gathered from the implemented system, and also from a survey, a quiz and interviews that we conducted. These data were analysed to determine if the gamified separation process yielded better results than the non-gamified separation process. Results from the experiments showed that there was no improvement in the participants' skill or understanding because of gamification, but that the gamified elements had a positive effect on both groups' motivation.

The increase in greenhouse gas (GHG) concentrations in the atmosphere, as well as the high rate of depletion of hydrocarbon-based resources have become a global concern. A major source of emissions of hydrocarbon vapours occur during loading and offloading operations in crude oil shuttle tanker transportation. The emitted gases have a typical composition of 60 % N2, 10 % CO2, 5% O2, 5 % C3H8, 10% CH4, 5% C2H6 and 5 % higher hydrocarbons. As a result, various methods aimed to add value to GHG to produce valuable fuels and chemical feedstock are being developed. This work incorporates the use of silica, polyurethane/zeolite and y-type zeolite membrane on an alumina support to selectively permeate methane and carbon dioxide from inert gases and higher hydrocarbons. The recovered gas is upgraded by dry reforming reactions employing rhodium/alumina membrane incorporated into a shell and tube reactor. Mixed gas permeation tests have been carried out with the permeate and feed gases sent to the online gas chromatograph (GC) equipped with a mass spectrometry (MS) detector and an automated 6-port gas sampling valve with a 30 mm HP- Plot Q column. The question is what mesoporous membrane can be highly selective for the separation of methane and carbon dioxide from inert gases and higher hydrocarbons, and what is the effect of temperature and feed gas pressure on the conversion of separated gases? Characterisation of the modified membranes was carried out using nitrogen physisorption measurements and showed the hysteresis isotherms corresponding to type IV and V, which is indicative of a mesoporous membrane. The surface area and the pore size were determined using the Barrett, Joyner, Halenda (BJH) desorption method, which showed the silica membrane had a larger surface area (10.69 m2 g-1) compared to zeolite (0.11 m2 g-1) and polyurethane/zeolite membrane (0.31 m2 g-1). Fourier Transform Infrared spectroscopy, Scanning Electron Microscope and Energy Dispersive X-ray Analysis confirmed the asymmetric deposition of silica, polyurethane, rhodium and zeolite crystals in the matrix of the alumina support. Single gas permeation tests showed that the synthesised y-type zeolite membrane at 293 K had a CH4/C3H8 selectivity of 3.11, which is higher than the theoretical value of 1.65. The permeating CH4 and C3H8 flux at 373 K and a pressure of 1 x 105 Pa was 0.31 and 0.11 mol s-1 m-2 respectively proving that zeolite has molecular sieving mechanism for separation of methane and propane. The silica membrane exhibited higher effectiveness for the separation of CO2 than the other membranes. For methane dry reforming using a supported rhodium membrane, an increase of the reaction temperature from 973 K to 1173 K showed an increase in conversion rate of CO2 and CH4 from less than 20% to over 90% while increasing the gas hourly space velocity (GHSV) did not have a noticeable effect. The study revealed the high potential of the zeolite and rhodium membrane for gas separation and dry reforming reactions concept in creating value-added carbon-based products from CO2 and CH4.

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Capes
Os separadores são equipamentos utilizados no processamento primário da indústria do petróleo com o objetivo de separar a mistura multifásica proveniente dos poços produtores. O trabalho avaliou o efeito dos dispositivos internos do vaso separador sobre a dinâmica do escoamento no processo de separação gás/óleo. Foi definido uma modelagem matemática com base na dinâmica de fluidos computacional (CFD) do separador horizontal bifásico. Adotou-se a abordagem Euleriana-Euleriana, considerando o modelo de mistura, disponibilizado no software Ansys CFX 15.0. O domínio consiste em um separador horizontal cilíndrico constituído de uma placa porosa que o divide em duas regiões: a região de separação primária, contendo três dispositivos internos (um defletor e duas chicanas) e a região de decantação. Foi gerada uma malha numérica empregando elementos tetraédricos, para a discretização das equações de conservação de massa, momento linear e de turbulência k padrão usando o método dos volumes finitos. Assumiu-se o escoamento em regimes permanente e transiente, isotérmico, com propriedades dos fluidos constantes e das forças interfaciais foram consideradas apenas as forças de arraste. Os resultados dos campos vetoriais de velocidade, assim como a fração volumétrica das fases indicam que a dinâmica do escoamento é fortemente dependente dos dispositivos internos. Na região de separação primária observou-se um alto nível de mistura causada pela turbulência gerada pelo impacto dos fluidos sobre a placa defletora posicionada imediatamente após a seção de entrada. A placa porosa possibilitou uma redução da turbulência dos fluidos, causada pela resistência do meio poroso ao escoamento.
The separators are equipments used in the primary processing of the petroleum industry to separate the multiphase mixture from the producing wells. The work evaluated the effect of the internal devices of the separator vessel on the flow dynamics in the gas/oil separation process. A mathematical model was defined based on computational fluid dynamics (CFD) of the horizontal two-phase separator. The Eulerian-Eulerian approach was adopted, considering the mixture model, available in Ansys CFX 15.0 software. The domain consists of a horizontal cylindrical separator consisting of a porous plate that divides it in to two regions: the primary separation, containing three internal devices (one deflector plate and two baffles) and the settling region. A numerical grid was generated employing tetrahedral elements, for the discretization of the mass conservation, linear momentum and k standard turbulence equations using the finite volume method. Isothermal flow with constant fluid properties in both steady state and transient regimes were assumed, and, from the interfacial forces, only the drag forces were considered. The velocity vector field results as well as the volumetric fraction of the phases indicate that the flow dynamics are strongly dependent on the internal devices. In the primary separation region, a high-level of mixing was observed due to the turbulence generated by the impact of the fluids on a deflector plate positioned immediately after the inlet section. The porous plate allowed a reduction of the turbulence of the fluids, caused by the resistance of the porous medium to the flow.

A system able to simultaneously separate and pump a gas-liquid mixture was developed.

It works efficiently and can be used in many applications (nuclear power plants,

pulp and paper processing, petroleum extraction, etc.). However, this pump and separator

system (PASS) was especially designed to handle air-oil mixture generated in

aero-engine lubrication systems. The PASS combines three important functions of the

scavenge part of the lubrication system: the deaeration and deoiling of the air-oil mixture

generated in the bearing and gearbox sumps and the pumping of the oil towards

the tank. These are critical functions for the engine. Indeed, a poor deoiling efficiency

leads to a high oil consumption. This reduces the flight endurance, increases the size

and weight of the oil tank and has a negative impact on the environment. Poor deaeration

and pumping characteristics lead to problems in the cooling and the lubrication of

the engine bearings.

Integrating a PASS into the lubrication system allows considerable improvements

(and simplification) to the lubrication system architecture. An important number of

components are suppressed: the vent lines, the deoiler, the cyclone deaerator and the

scavenge pumps. This reduces the size and the weight of the lubrication system and

increases its reliability. Furthermore, an important part of this PhD thesis focuses on

reducing the oil consumption in the PASS. This improves the flight endurance, reduces

engine maintenance and working costs and is profitable to the environment.

In addition to the development of an advanced PASS design system, the objective of

this thesis was to obtain a good understanding of the separation processes occurring in

the PASS and to develop theoretical models able to predict the separation performance

for every working condition encountered in a typical aircraft flight. To achieve this

goal, three main tasks were performed: the development of different two-phase measurement

systems, the experimental tests of four different PASS architectures and the

theoretical development (after an extensive literature review) of correlations predicting

the performance of the PASS in function of the working conditions. Five specific aspects

of the PASS were studied: the inlet flow, the deoiling efficiency, the deaeration efficiency,

the pumping efficiency and the pressure drop. Finally, the models that have been developed

with the help of the measurement systems and of the experiments have been

integrated in a complete model of the lubrication system (under the EcosimPro modelling

environment). This helps to predict real in flight PASS working conditions and

performance. Indeed, the PASS is very sensitive to the engine working conditions and

an optimisation of the prototype size and performance is only feasible with an accurate

knowledge of these working conditions and a complete lubrication system model.

Finally, with the results of this PhD thesis, a new PASS design, optimised for different

aero-engine lubrication systems, is presented.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Analyse et dosage des composes soufres presents dans une coupe lourde du petrole aramco 90 par chromatographie gazeuse avec detection soit par photometrie de flamme soit par spectrometrie de masse haute resolution. Etude comparative des methodes d'analyse. Etude des composes soufres dans des echantillons de petrole de rozel point et de schiste bitumineux de timahdit grace a l'identification par synthese de nouvelles familles d'alkylbenzo (b) thiophenes

This thesis is a study of naturally occurring radioactive materials (NORM) activity concentration, gamma dose rate and radon (222Rn) exhalation from the waste streams of large-scale onshore petroleum operations. Types of activities covered included; sludge recovery from separation tanks, sludge farming, NORM storage, scaling in oil tubulars, scaling in gas production and sedimentation in produced water evaporation ponds. Field work was conducted in the arid desert terrain of an operational oil exploration and production region in the Sultanate of Oman. The main radionuclides found were 226Ra and 210Pb (238U - series), 228Ra and 228Th (232Th - series), and 227Ac (235U - series), along with 40K. All activity concentrations were higher than the ambient soil level and varied over several orders of magnitude. The range of gamma dose rates at a 1 m height above ground for the farm treated sludge had a range of 0.06 0.43 µSv h 1, and an average close to the ambient soil mean of 0.086 ± 0.014 µSv h 1, whereas the untreated sludge gamma dose rates had a range of 0.07 1.78 µSv h 1, and a mean of 0.456 ± 0.303 µSv h 1. The geometric mean of ambient soil 222Rn exhalation rate for area surrounding the sludge was mBq m 2 s 1. Radon exhalation rates reported in oil waste products were all higher than the ambient soil value and varied over three orders of magnitude. This study resulted in some unique findings including: (i) detection of radiotoxic 227Ac in the oil scales and sludge, (ii) need of a new empirical relation between petroleum sludge activity concentrations and gamma dose rates, and (iii) assessment of exhalation of 222Rn from oil sludge. Additionally the study investigated a method to determine oil scale and sludge age by the use of inherent behaviour of radionuclides as 228Ra:226Ra and 228Th:228Ra activity ratios.

Lo scopo di questo elaborato è quello di illustrare l'analisi fluidodinamica che segue la progettazione di un separatore compatto tipo ILS (In-Line Separator), utilizzato nel campo dell'Oil & Gas. L'attività di tesi è stata svolta analizzando i flussi bifase sia con tecniche sperimentali che numeriche, con l'ausilio di un circuito di test e del software commerciale AnsysFluent. Lo studio sperimentale è stato svolto nei laboratori del di fluidodinamica applicata e miscelazione presso il DICAM, Università di Bologna. Lo studio ha avuto come punto di partenza la mappatura della regione di funzionamento del dispositivo. Successivamente, tramite un sistema PIV (Particle Image Velocimetry) ed alla tecnica di indagine a retroilluminazione, sono state effettuate campagne di acquisizione dati monofase e bifase, gas-liquido. I dati sperimentali così ottenuti sono stati utilizzati come benchmark per valutare i modelli e i metodi di soluzione numerica utilizzati per le seguenti simulazioni CFD (Computational FluidDynamics ). Infine è stato effettuato un confronto sia qualitativo che quantitativo tra i risultati ottenuti tramite i due diversi approcci di progettazione.

Thesis (Ph. D.)--University of Florida, 2001.
Title from first page of PDF file. Document formatted into pages; contains viii, 118 p.; also contains graphics. Vita. Includes bibliographical references (p. 115-117).

This dissertation presents the results from an experimental study of three-dimensional turbulent tip gap flow in a linear cascade wind tunnel with 3.3% chord tip clearance with and without moving endwall simulation. Experimental measurements have been completed in Virginia Tech low speed linear cascade wind tunnel. A 24" access laser-Doppler velocimeter (LDV) system was developed to make simultaneous three-velocity-component measurements. The overall size of the probe is 24"à 37"à 24"and measurement spatial resolution is about 100 μm. With 24" optical access distance, the LDV probe allows measurements to be taken from the side of the linear cascade tunnel instead of through the bottom of the tunnel floor. The probe has been tested in a zero-pressure gradient two-dimensional turbulent boundary layer. Experimental measurements (oil flow visualization, pressure measurement, and LDV measurement) for the stationary wall captured the major flow structures of the tip leakage flow in the linear compressor cascade, such as tip leakage vortex, tip leakage vortex separation and tip separation vortex. Large velocity gradients in the tip leakage vortex separation, tip leakage vortex, and tip separation vortex regions generate large production of the Reynolds stresses and turbulent kinetic energy. One of the most interesting features of the tip leakage flow is the bimodal velocity probability histograms of the v component due to the unsteady motion of the flow in the interaction region between the tip leakage vortex and tip leakage jet. The tip separation vortex, tip leakage vortex separation, and tip leakage vortex contain most of turbulent kinetic energy and generate the highest dissipation rate. Relative motion of the endwall significantly affects the tip gap flow structures, especially in the near wall region. Compared to the stationary wall case, velocity gradients in the near wall region for the moving wall case are much smaller and lower velocity gradients in the near wall region cause the low production of Reynolds stresses and turbulent kinetic energy. Similar to the stationary wall case, high Reynolds stresses and turbulent kinetic energy values are mainly located in the vicinity of the tip leakage vortex and tip separation vortex region. The bimodal velocity probability histograms of the v component are also found at the same locations. The tip separation vortex with most of the turbulent kinetic energy generates the highest dissipation rate. The dissipation rate in the tip leakage vortex region is reduced with the decrease of turbulent kinetic energy under the moving wall effect.
Ph. D.

Les exploitant aériens cherchent à réduire toujours davantage le coût d'utilisation et d'opération de maintenance des hélicoptères ainsi qu'à limiter leur impact environnemental. Par conséquent, les motoristes tels que Safran Helicopter Engines doivent constamment améliorer les performances de leurs moteurs. Cette amélioration passe notamment par la réduction des consommations de carburants et d'huile de lubrification. La consommation d'huile est liée en grande partie à la formation d'un brouillard diphasique air-huile au sein des paliers de roulements des arbres du moteur. L'air est continûment évacué en transportant des inclusions d'huile vers l'extérieur. Pour limiter ces rejets d'huile, un séparateur en rotation est utilisé pour récupérer l'huile et évacuer l'air. Afin de prédire avec davantage de précision la consommation d'huile et les pertes de charges induites par le séparateur, la présente thèse développe une stratégie d'analyse des écoulements diphasiques au sein des séparateurs. Cette stratégie s'appuie en premier lieu sur des simulations numériques du brouillard d'huile basées sur une approche Euler-Lagrange. Ces simulations permettent d'une part d'analyser l'écoulement d'air et les pertes de charges du séparateur et d'autre part d'appréhender les mécanismes de la séparation de l'huile et d'analyser la consommation en fonction des conditions de fonctionnement. Parallèlement, grâce au financement du projet européen E-Break, un banc d'essais dégazeur a été conçu dans le cadre de cette thèse et réalisé à l'Université Libre de Bruxelles. Des analyses croisées entre essais et simulations permettent de valider la méthodologie de simulation. Cependant, si les pertes de charges sont correctement prédites par le calcul, des efforts supplémentaires sont nécessaires, aussi bien sur la précision des mesures que sur la modélisation de l'écoulement diphasique, pour assurer une prédiction satisfaisante de la consommation d'huile
Air operators try to reduce ever more operation and maintenance costs of helicopters as well as to limit their environmental impact. Consequently, engine manufacturers such as Safran Helicopter Engines must constantly improve the performance level of the engines they develop. To achieve such an improvement, oil and kerosene consumption must be reduced. Oil consumption is mostly due the formation of an oil mist inside bearing chambers. As the air is continuously scavenged, it carries along oil droplets out of the engines. In order to limit the oil wastes, a separator is used which recovers oil drops carried by the owing air that is vented out. In order to predict with a better level of accuracy the oil consumption and the pressure losses induced by the separator, the present thesis develops a strategy to analyse the two-phase flow within the separator. This strategy relies in the first place on Euler-Lagrange numerical simulation of the oil mist which allow on the one hand to compute the turbulent air flow and the pressure drop induced by the separator and on the other hand to better understand the separation mechanisms and to predict the oil consumption for various operating conditions. Besides, thanks to the funding of the E-Break European project, a test bench has been designed in the framework of this PhD and set up at the Université Libre de Bruxelles. Cross comparisons between measurements and simulations allow validating the numerical methodology. However, even though pressure drops are correctly predicted by the simulation, improvements are still needed, regarding both the measurement accuracy and the two-phase numerical modelling, in order to provide a satisfactory prediction of the oil consumption

Petróleo Brasileiro S.A.
O presente trabalho aborda o comportamento da planta de processamento primário com alimentação por fluxo em padrão de golfadas. O fluxo no sistema de tubulações é descrito por um modelo de parâmetros concentrados, fornecendo as características principais necessárias para o controle da planta, e a resposta dinâmica desta pode então ser analisada. Usando a estratégia de controle tradicional verifica-se que as oscilações de fluxo são transmitidas para as vazões de saída de líquido e gás, para obter uma vazão de saída mais estável é permitida a flutuação de carga no separador dentro de uma tolerância, isto é possível reduzindo a atuação do controlador e estabelecendo um controle adicional diretamente na válvula de entrada.
The present work addresses the behavior of a primary processing plant subjected to slug flow pattern at its entrance. The flow in a pipeline system is described by a simplified concentrated parameter model, which preserves the main physical features that are important to control the plant. The dynamic response of the plant is then analyzed. Using a standard control strategy for the gas liquid separator, it is seen that the flow oscillations are transmitted to the liquid and gas outlets. In order to obtain a more stable outlet flow, the liquid level in the separator is then allowed to fluctuate within a given range, by reducing the effect of the controller constants, and establishing an additional control directly on the inlet entrance valve.