Desalination is a technique of producing fresh water from the saline water. Industrial desalination of sea water is becoming an essential part in providing sustainable source of fresh water for a large number of countries around the world. Thermal process being the oldest and most dominating for large scale production of freshwater in today¿s world. Multi-Stage Flash (MSF) distillation process has been used for many years and is now the largest sector in the desalination industry. In this work, a steady state mathematical model of Multistage Flash (MSF) desalination process is developed and validated against the results reported in the literature using gPROMS software. The model is then used for further investigation. First, a steady state calcium carbonate fouling resistance model has been developed and implemented in the full MSF mathematical model developed above using gPROMS modeling tool. This model takes into consideration the effect of stage temperature on the calcium carbonate fouling resistance in the flashing chambers in the heat recovery section, heat rejection section, and brine heaters of MSF desalination plants. The effect of seasonal variation of seawater temperature and top brine temperature on the calcium carbonate fouling resistance has been studied throughout the flashing stage. In addition, the total annual operating cost of the MSF process is selected to minimise, while optimising the operating parameters such as seawater rejected flow rate, brine recycle flow rate and steam temperature at different seawater temperature and fouling resistance. Secondly, an intermediate storage between the plant and the client is considered to provide additional flexibility in design and operation of the MSF process throughout the day. A simple polynomial based dynamic seawater temperature and different freshwater demand correlations are developed based on actual data. For different number of flash stages, operating parameters such as seawater rejected flow rate and brine recycle flow rate are optimised, while the total annual operating cost of the MSF process is selected to minimise.The results clearly show that the advantage of using the intermediate storage tank adds flexible scheduling in the MSF plant design and operation parameters to meet the variation in freshwater demand with varying seawater temperatures without interrupting or fully shutting down the plant at any time during the day by adjusting the number of stages. Furthermore, the effect of non-condensable gases (NCG) on the steady state mathematical model of MSF process is developed and implemented in the MSF model developed earlier. Then the model is used to study effect of NCG on the overall heat transfer coefficient. The simulation results showed a decrease in the overall heat transfer coefficient values as NCG concentrations increased. The model is then used to study the effect of NCG on the design and operation parameters of MSF process for fixed water demand. For a given plant configuration (fixed design) and at different seawater and steam temperatures, a 0.015 wt. % of NCG results in significantly different plant operations when compared with those obtained without the presence of NCG. Finally, for fixed water demand and in the presence of 0.015 wt. % NCGs, the performance is evaluated for different plant configurations and seawater temperature and compared with those obtained without the presence of NCG.

Yes / In this paper, a dynamic model of fouling is presented to predict the crystallization of calcium carbonate and magnesium hydroxide inside the condenser tubes of Once-Through Multistage Flash (MSF-OT) desalination process. The model considers the combination of kinetic and mass diffusion rates taking into account the effect of temperature, velocity and salinity of the seawater. The equations for seawater carbonate system are used to calculate the concentration of the seawater species. The effects of salinity and temperature on the solubility of calcium carbonate and magnesium hydroxide are also considered. The results reveal an increase in the fouling inside the tubes caused by crystallization of CaCO3 and Mg(OH)2 with increase in the stage temperature. The intake seawater temperature and the Top Brine Temperature (TBT) are varied to investigate their impact on the fouling process. The results show that the (TBT) has greater impact than the seawater temperature on increasing the fouling.

Middle Mississippian ramp carbonates in Kentucky (Fort Payne to Salem interval) form a large scale depositional supersequence (0 to 500 feet thick, approximately 8 m. y. duration). It formed on and in front of the abandoned Early Mississippian Borden deltaic marine paleoshelf, which had up to 100 m of relief above the adjacent starved basin. Major facies consist of marine quartz sandstone and shale; peritidal carbonates; high-energy ramp margin, crinoidal-bryozoan grainstones; deeper ramp mounds, skeletal grainstone/packstone sheets and channel-fills interlayered with shale or calcisiltite; and slope deposits of siliceous calcisiltite. Regional slopes on the paleoshelf edge and ramp margin are 0.5 to 2.5 mIkm (less than 0.25 degrees), although clinoforms of 2 to 10 degrees occur locally associated with mounds and depositional lobes. The supersequence LST is dominated by mounds interlayered with green shaly, deeper ramp facies. The mounded units are located in a fairway that is normal to the Borden margin but parallel to the Appalachian Grainger deltaic shelf. No TST is evident, except for a glauconite horizon capping the Borden paleoshelf. The supersequence HST consists of at least eight third-order sequences (each approximately 1 m.y. duration), the older ones downlapping onto the shelf 20 to 30 m deep, the younger ones downlapping into the deeper basin (over 150 m water depth). Sequences show marked toplap with the upper sequence boundary. The third-order sequences locally have lowstand sands, some of which may be associated with a paleodrainage system off the Borden paleo shelf. They lack recognizable TSTs, but have well-developed prograding HST units of nearshore shale and peritidal dolomite, skeletal packstone/grainstone banks, and siliceous calcisiltite slope facies. The supersequence correlates with a global sea level cycle in the lower Visean terminating in a major sea-level fall. The highly clinofonned toplapping supersequence reflects this long term, sea-level fall which prevented space from being created on the old delta top. The third-order sequences, although mappable between the sections, are not easily correlated with global third order cycles. / Master of Science

[pt] A caracterização das zonas de dano no entorno das falhas geológicas é importante para a indústria de óleo e gás pois as estruturas geológicas presentes podem afetar tanto os processos de fluxo nos reservatórios quanto o comportamento geomecânico dos campos. Como aproximação inicial, a espessura das zonas de dano tem sido correlacionada diretamente com os rejeitos de falha. No entanto, a dispersão dos dados levantados em campo indica que outras variáveis, além do rejeito, também podem afetar à espessura da zona de dano, particularmente em rochas carbonáticas. Neste sentido, o objetivo desta dissertação é a avaliação do impacto das propriedades geomecânicas dos carbonatos na previsão da espessura da zona de dano em falhas geológicas dos campos do pré-sal Brasileiro. Em função das incertezas na definição das propriedades geomecânicas, estas foram inferidas a partir de correlações empíricas que foram estabelecidas com a porosidade. Em seguida, fazendo uso de modelagem numérica, se realizou um planejamento de experimentos, obtendo-se a espessura da zona de dano a partir de diferentes combinações de parâmetros geomecânicos. Logo, empregando o método da superfície de resposta, foram definidos modelos de regressão que preveem a espessura da zona de dano a partir do rejeito e da porosidade das rochas carbonáticas avaliadas. Os resultados indicam que os modelos de regressão propostos permitem estimar espessuras de zonas de dano consistentes com as observações em campo, e, portanto, podem ser utilizadas para uma caracterização preliminar das zonas de dano nos processos exploratórios da indústria de óleo e gás. / [en] The characterization of damage zones surrounding geological faults is important for the oil and gas industry, as the geological structures present can affect both the fluid flow in reservoirs and the geomechanical behavior of fields. As an initial approximation, the width of damage zones has been directly correlated with fault throw. However, the dispersion of data collected in the field indicates that other variables, besides fault throw, can also affect the width of the damage zone, particularly in carbonate rocks. In this sense, the objective of this dissertation is to evaluate the impact of geomechanical properties of carbonates on the prediction of the thickness of the damage zone in geological faults in the Brazilian pre-salt fields. Due to uncertainties in defining geomechanical properties, they were inferred from empirical correlations that were established with porosity. Then, using numerical modeling, a design of experiments was carried out, obtaining the width of the damage zone from different combinations of geomechanical parameters. Next, employing the response surface method, regression models were defined that predict the width of the damage zone from fault throw and porosity of the evaluated carbonate rocks. The results indicate that the proposed regression models allow for the estimation of damage zone widths consistent with field observations and therefore can be used for preliminary characterization of damage zones in exploration processes in the oil and gas industry.

I takt med att behovet av att minska utsläppen av växthusgasen ökar, ökar även intresset för negativa utsläpp. En lovande teknik för att uppnå negativa utsläpp är koldioxidlagring från biomassa, även kallad BECCS (Bio-Energy Carbon Capture and Storage). Trots teknologins mognad är de stora energibehoven vid lösningsmedelsregenerering ett hinder för storskalig implementering. I den här studien utforskas den relativt okända kinetiken för lösningsmedelsregenerering av kaliumkarbonat i ett steg för att optimera processen. Dessutom undersöks möjligheten att använda vanadin(V)oxid som katalysator för att förbättra desorptionshastigheten. Experimentella analyser utfördes i en sats-reaktor och gick ut på att undersöka förändringen av lösningsmedlets loading över tid genom regelbundna titreringar. Utöver detta undersöks den påverkan som temperatur och omrörning har på desorptionshastigheten. Experimenten utförs vid atmosfärstryck och temperaturer från 80°C till 100°C. Resultaten visade på god repeterbarhet trots svårigheter med temperaturöverskridningar. Desorptionshastigheten var lägre vid 80°C och 90°C än vid 100°C, men de logaritmiska hastighetskonstanterna följde inte en linjär relation mot temperaturinverserna vilket antyder att reaktionen är begränsad av massöverföring. Vidare påverkade inte användandet av en katalysator desorptionskinetiken märkbart, vilket än en gång antyder ett massöverföringsberoende. Slutligen visades ingen märkbar skillnad i desorptionshastighet trots olika omrörningshastigheter. Detta beror troligen på den redan höga massöverföringen som sker vid kokpunkten. Sammanfattningsvis bidrar denna studie med insikter för att förbättra effektiviteten hos regenereringen av lösningsmedel vid BECCS, vilket är avgörande för att motverka utsläppen och möta utmaningarna med klimatförändringarna.

Cores, quarry exposures, and exploratory wells in the Paleogene Albemarle Basin, North Carolina sample the transition between the southern carbonate and northern siliciclastic provinces of the eastern U.S. continental shelf succession. The study area includes the relatively positive Cape Fear Arch on the Onslow Block to the south, and the slowly subsiding (1.5 cm/ky) Albemarle Block to the north. The Paleogene supersequence set boundary is a hardground on Cretaceous shoreface/shallow-shelf mollusk facies. It is overlain by a thin Paleocene sequence of deeper offshore, glauconitic fine sands to deep marine silt-shale. Five regionally mappable, vertically stacked Eocene sequences are 0 to 30 m thick and contain coastal sands, shoreface sandy-mollusk rudstones, offshore bryozoan grainstone-packstones and subwave base fine wackestone-packstone and marl. The Eocene sequences commonly are bounded by hardgrounds, overlain by thin local lowstand sands and consist of a thin transgressive unit (commonly absent), overlain by an upward shallowing highstand marine succession. On the arch, lowstand and transgressive units may be condensed into lags. The Lower Oligocene succession on the arch has a single marl to fine foram sand dominated sequence whereas downdip, two to three sequences are developed, capped by nearshore sandy molluscan facies. The Upper Oligocene is dominated by possibly three sequences composed of basal, thin sands up into variably sandy mollusk rudstone. Sequence development was influenced by differential movement of the basement blocks, coupled with increasing 3rd order eustatic sea level changes during global cooling. This was coupled with swell-wave and current sweeping of the shelf that effectively decreased available accommodation by 20 to 30 m, and generated the distinctive hardgrounds on sequence boundaries, and variable development of lowstand and transgressive system tracts. The well developed highstands reflect maximum accommodation allowing deposition of an upward shallowing succession that terminated at the depth of wave abrasion on the open shelf. The sequence stratigraphic development contrasts markedly with that from tropical shelves. / Master of Science

Des films cellulaires pour usage piézoélectrique ont été développés par étirage bi-axial suivi d’un gonflement contrôlé à partir de films composites en polypropylène (PP) chargés de particules minérales: carbonate de calcium (CaCO3) et talc. Afin d’atteindre des propriétés piézoélectriques convenables, la morphologie cellulaire des films a été basée sur une revue de littérature pour l’épaisseur (b) des cellules, leur aspect (a/b) défini par le rapport entre leur longueur (a) et leur épaisseur (b), ainsi que l’épaisseur (t) de leurs parois. De façon à évaluer l’impact de la taille des particules, de leur concentration, de leur forme et de la température d’étirement sur la morphologie cellulaire de films, des échantillons ont été produits en extrudant des feuilles de 0,9 mm de PP/CaCO3 (12 μm, sphérique), PP/CaCO3 (6 μm, sphérique), PP/CaCO3 (3 μm, sphérique) et PP/talc (10 μm, plat). Ces feuilles ont été ensuite étirées bi-axialement à des températures de 152, 155, 158 et 160°C à un taux d’étirement de 2,4 m/min. Suite à l’étirement bi-axial, des épaisseurs de films variant entre 40 et 120 μm ont été obtenues. Les films ont ensuite subi un traitement d’expansion (diffusion d’azote à 130°C) afin de gonfler les cellules. L’analyse d’images obtenues par microscopie électronique à balayage (MEB) a servi à quantifier la morphologie cellulaire. Les résultats obtenus ont montré que les films de PP/CaCO3 (3 μm) n’ont pas donné de cellule, alors que ceux de PP/CaCO3 (12 μm) étirés à 152°C ont donné les meilleures morphologies cellulaires à des concentrations massiques de 35%. Ces «meilleures» morphologies correspondent à t = 3,6 μm, a/b = 5,6 et b = 13,6 μm. La valeur de la contrainte ultime lors de l’étirement s’est avérée proportionnelle à la quantité et à la qualité des cellules produites. Finalement, le ratio d’étirement, auquel la contrainte ultime est atteinte, est constant à environ 3,3, peu importe la taille des particules, leur concentration ou la température d’étirement. Ceci suggère que la matrice et la vitesse d’étirement sont responsables de la modulation du ratio d’étirement auquel la délamination matrice-particules se produit. Les travaux ont démontré que la concentration et la taille des particules sont inversement proportionnelles à l’épaisseur des parois cellulaires proportionnelles, au nombre de cellules observées et à la hauteur de ces cellules. L’abaissement de la température d’étirement a pour effet d’amplifier les effets respectifs associés à la taille et à la concentration des particules. / Piezoelectric cellular films have been developed, by bi-axial stretching followed by controlled cell inflation, from composite polypropylene (PP) films filled with mineral particles of calcium carbonate (CaCO3) and talc. An exhaustive literature review was done to identify the optimum values for the parameters describing the cellular structure promoting piezoelectricity. The most important morphological parameters associated with the structural stiffness of the films, which is inversely proportional to the piezoelectric coefficient, are: cell aspect ratio (a/b), cell thickness (b) and cell wall thickness (t). To optimize the cellular structure created during the bi-axial stretching step, PP films filled with CaCO3 and talc particles of different sizes and shapes were stretched at different temperatures and then underwent a gas diffusion expansion to improve the cell morphology. Initially, 0.9 mm sheets of PP/CaCO3 (12 μm, spherical), PP/CaCO3 (6 μm, spherical), PP/CaCO3 (3 μm, spherical) and PP/talc (10 μm, platy) were extruded before being bi-axially stretched at 152, 155, 158 and 160°C under a stretching rate of 2.4 m/min in both directions. The gas diffusion expansion treatment of the resulting films was done with nitrogen at 130°C. The cell morphology analysis was done from scanning electron microscopy (SEM) images to quantify a/b, b and t. It was observed that films made of PP/CaCO3 (3 μm) did not yield any cells. However, those made from PP/CaCO3 (12 μm) and stretched at 152°C had the best cellular structure when the CaCO3 concentration was 35% wt. The best morphology (t = 3.6 μm, a/b = 5.6 and b = 13.6 μm) was achieved within the targeted values to optimize piezoelectric properties. It was found that the ultimate stress during stretching depends on the cellular quality of the resulting film and that, independent of the size of CaCO3 or talc particles, their concentration or the stretching temperature. It was also observed that the stretching ratio at which the ultimate stress was obtained was always around 3.5. This suggested that both the stretching speed and the polymer matrix were responsible for the stretching ratio at which delamination occurs. As expected, particle concentration and their size were shown to be inversely proportional to cell wall thickness, but proportional to the number of cells observed and to their height. Decreasing the stretching temperature amplified the respective effects of the cell morphology associated with particles size and concentration.

La signature du Protocole de Kyoto par le Canada en décembre 2002 et les nouvelles normes environnementales qui en découleront nous forcent déjà à trouver des solutions pour réduire de façon significative les émissions de gaz à effet de serre, et en particulier le CO₂. Une des façons de réduire de telles émissions consiste à séquestrer le CO2 par la carbonatation minérale en utilisant des silicates de magnésium. Ces minéraux sont abondants dans les rejets des mines d'amiante du sud du Québec. La présente étude propose donc une revue des procédés de capture de CO2 et une étude approfondie sur la carbonatation gaz-solide à basse pression dans des environnements secs et humides. La structure évolutive du chrysotile et sa réactivité en fonction de la température, l'humidité, la variation du pourcentage de CO₂ dans le mélange gazeux, le pré-conditionnement thermique et le dopage alcalin ont été analysés et caractérisés par.un système couplé TG-DTA-MS, par XPS et par la DRX. Le résultat le plus important de cette étude est que le chrysotile dopé 10% Cs, dans un environnement gazeux humide, permet d'augmenter le taux de carbonatation par un facteur 2.5 par rapport au chrysotile vierge.

La symbiose mycorhizienne joue un rôle significatif en agriculture, notamment en facilitant la nutrition des plantes et l'amélioration de leur résistance envers les stress biotiques et abiotiques. Cette étude visait à évaluer cinq souches de champignons mycorhiziens arbusculaires pour leur capacité à s'adapter aux sols alcalins d'Haïti. L'expérience a été réalisée en serre pour examiner l'effet combiné du champignon Rhizophagus irregularis et du carbonate de calcium sur la biomasse aérienne, la colonisation mycorhizienne et la composition minérale du poireau. Les résultats ont montré une amélioration significative de la biomasse aérienne des plantes sous l'effet de l'inoculation mycorhizienne, cette amélioration persistant à tous les niveaux de carbonate de calcium. Par ailleurs, les plantes inoculées avec trois des cinq souches de champignon (DAOM 241558, DAOM 197198(AAC) et DAOM 197198(PT)) ont généré un rendement en biomasse supérieur à celui du témoin non inoculé, avec des accroissements de l'ordre de 87%. En ce qui concerne le taux de colonisation, les plantules inoculées ont montré un niveau de colonisation mycorhizienne variant de 45% à 61% selon les souches de champignon, qui diminue avec l'augmentation de la concentration de carbonate de calcium. Les résultats révèlent une corrélation positive entre la biomasse aérienne et le taux de colonisation mycorhizienne. En effet, plus la colonisation est élevée, plus le rendement en biomasse aérienne augmente. Cette observation s'applique à toutes les souches, à l'exception de la souche DAOM 234181 qui, malgré un taux de colonisation élevé, génère un faible rendement en biomasse chez la plante inoculée. Enfin, une teneur plus importante des plantes en phosphore, en potassium et en zinc a été observée lorsque celles-ci ont été inoculées avec l'une de ces trois souches, soit DAOM 241558, DAOM 197198(AAC) et DAOM 197198(PT), et ceci même à des concentrations élevées de carbonate de calcium.

La formation de carbonates de magnésium et/ou calcium à l’aide du CO₂ atmosphérique (carbonatation minérale) permet la séquestration permanente du CO₂. Puisque la réaction se produit naturellement dans certains résidus miniers, il est possible d’utiliser ces derniers dans un esprit de développement durable. Le but de cette recherche est d’optimiser la carbonatation minérale de résidus miniers par des manipulations physico-chimiques et par l’ajout de sels organiques neutres. Cet ajout devrait permettre de faciliter la mise en solution des ions magnésium contenus dans le résidu minier et ainsi faciliter la précipitation de carbonates de magnésium. Des tests en eudiomètre ont été réalisés en variant différents paramètres tels que la concentration de CO₂ dans la phase gazeuse, la teneur en eau des résidus, le type de résidus utilisé et en ajoutant divers sels organiques tels que citrate, oxalate et EDTA de sodium en différentes concentrations afin de favoriser la carbonatation minérale. Les essais ont été réalisés sur différents résidus miniers riches en silicates/oxydes/hydroxydes de magnésium provenant des mines de Black Lake, Asbestos, Dumont, Raglan et Renard. Les résultats indiquent que le résidu plus réactif est de loin Dumont, suivi par Asbestos et Black Lake. Raglan et Renard sont très peu réactifs. La teneur en eau des résidus pour obtenir une réaction optimale varie de 20% à 60%. L’eau interstitielle est un solvant nécessaire pour la mise en solution des ions Mg, mais trop d’eau nuit à la diffusion du CO₂. Une relation linéaire entre la concentration en CO₂ dans la phase gazeuse et le taux d’absorption a été observée. En remplaçant l’eau par des solutions de chélates, l’absorption de CO₂ a pu être augmentée de 24% avec une solution d’EDTA d’un pH de 8,35 concentrée à 0,19M. Cependant, la meilleure solution varie en nature autant qu'en concentration d'un résidu minier à l'autre. Ces données montrent qu’il est possible de favoriser la séquestration naturelle de CO₂ de manière significative.