Yes / Three equations of state with a group contribution model for binary interaction parameters were employed to calculate the vapor-liquid equilibria of synthetic and real natural gas mixtures with heavy fractions. In order to estimate the binary interaction parameters, critical temperatures, critical pressures and acentric factors of binary constituents of the mixture are required. The binary interaction parameter model also accounts for temperature. To perform phase equilibrium calculations, the heavy fractions were first discretized into 12 Single Carbon Numbers (SCN) using generalized molecular weights. Then, using the generalized molecular weights and specific gravities, the SCN were characterized. Afterwards, phase equilibrium calculations were performed employing a set of (nc + 1) equations where nc stands for the number of known components plus 12 SCN. The equations were solved iteratively using Newton's method. Predictions indicate that the use of binary interaction parameters for highly sour natural gas mixtures is quite important and must not be avoided. For sweet natural gas mixtures, the use of binary interaction parameters is less remarkable, however.

Miscible gas flooding is a common method for enhanced oil recovery. Reliable design of miscible gas flooding requires compositional reservoir simulation that can accurately predict the fluid properties resulting from mass transfer between reservoir oil and injection gas. Drawbacks of compositional simulation are the efficiency and robustness of phase equilibrium calculations consisting of flash calculations and phase stability analysis. Simulation of multicontact miscible gas flooding involves a large number of phase equilibrium calculations in a near-critical region, where the calculations are time-consuming and difficult. Also, mixtures of reservoir oil and solvent such as CO₂ and rich gas can exhibit complex phase behavior at temperatures typically below 120°F, where three hydrocarbon-phases can coexist. However, most compositional simulators do not attempt to solve for three hydrocarbon-phases because three-phase equilibrium calculations are more complicated, difficult, and time-consuming than traditional two-phase equilibrium calculations. Due to the lack of robust algorithms for three-phase equilibrium calculations, the effect of a third hydrocarbon-phase on low-temperature oil displacement is little known. We develop robust and efficient algorithms for phase equilibrium calculations for two and three phases. The algorithms are implemented in a compositional reservoir simulator. Simulation case studies show that our algorithms can significantly decrease the computational time without loss of accuracy. Speed-up of 40% is achieved for a reservoir simulation using 20 components, compared to standard algorithms. Speed-up occurs not only because of improved computational efficiency but also because of increased robustness resulting in longer time-step sizes. We demonstrate the importance of three-phase equilibrium calculations, where simulations with two-phase equilibrium approximations proposed in the literature can result in complete failure or erroneous simulation results. Using the robust phase equilibrium algorithms developed, the mechanism is investigated for high efficiency of low-temperature oil displacements by CO₂ involving three hydrocarbon-phases. Results show that high displacement efficiency can be achieved when the composition path goes near the critical endpoint where the gaseous and CO₂-rich liquid phases merge in the presence of the oleic phase. Complete miscibility may not be developed for three-phase flow without considering the existence of a tricritical point. / text

Sulphate-rich wastewater is an increasing concern for industries as LKAB. The water chemistry of the LKAB Kiruna water system is characterized by high alkalinity, high pH (pH 7.5-9.0) and high concentrations of chemical species and soluble minerals. The sulphate content in the water system of Kiruna is associated with the dissolution of calcium sulphate as anhydrite (CaSO4) and gypsum (CaSO4 2H2O). However, the high concentrations of sulphate in the effluents from the LKAB Kiruna operation are unique for iron ore mining.    The aim of the thesis was to study and evaluate the behavior of sulphate in the process water system of the Kiruna concentrator plants. This was done by laboratory grinding (leaching tests), equilibrium calculations with the HSC software and mass balancing of the concentrator KA3 in Kiruna. The highest concentrations of sulphate have been detected in the process water of KA3, hence the focus has been on KA3 regarding sampling, evaluation and comparison. Water treatment technologies for sulphate and the effect of process water on ore processing have not been included in this project.   The laboratory grinding was done using process water and ore from the concentrator KA3. During the experimental work with laboratory grinding the parameters pH, temperature and operating times for primary- and secondary grinding, respectively, were varied. The observations from the experimental work were further confirmed by equilibrium calculations and mass balancing. The following conclusions were drawn.     Anhydrite/gypsum is not leached from the ore during ore processing with process water having concentrations of sulphate already close to the saturation point at approximately 1800 mg/L. If the process water is diluted with water with lower sulphate content, e.g. mine water or a diluted return water from the pond system (e.g. during spring flood), anhydrite/gypsum in ore will be dissolved until the sulphate concentration reaches the saturation point. The ionic strength of the process water controls the saturation point and thus the sulphate concentration. Leaching of anhydrite/gypsum in saturated process water, with respect to sulphate, is not affected by grinding time or adjusted conditions in the process water, such as temperature or pH value.    For further work, it is recommended to investigate the behavior of sulphate in the tailings pond system to increase knowledge of the overall behavior in the water system. In addition, a similar investigation of the behavior of uranium in the process water is recommended in order to face future environmental standards.

This thesis investigates sustainability measures for quicklime and cement clinker production. It is the aim of this thesis to contribute to the effort of creating a more sustainable modus of industrial production. The methods used comprises process simulations through multicomponent chemical equilibrium calculations, fuel characterization and raw materials characterization through dynamic rate thermogravimetry. The investigated measures relate to alternative fuels, co-combustion, oxygen enrichment, oxyfuel combustion, mineral carbonation and optimizing raw material mixes based on thermal decomposition characteristics. The predictive multicomponent chemical equilibrium simulation tool developed has been used to investigate new process designs and combustion concepts. The results show that fuel selection and oxygen enrichment influence energy efficiency, and that oxyfuel combustion and mineral carbonation could allow for considerable emission reductions at low energy penalty, as compared to conventional post-combustion carbon dioxide capture technologies. Dynamic rate thermogravimetry, applied to kiln feed limestone, allows for improved feed analysis with a deeper understanding of how mixing of different feed materials will affect the production processes. The predictive simulation tool has proven to be of practical value when planning and executing production and full scale campaigns, reducing costs related to trial and error. The main conclusion of this work is that several measures are available to increase the sustainability of the industry.

Military aircraft that require high maneuverability, durability, ballistic protection, reparability, and energy efficiency require structural alloys with low density, high toughness, and high strength. Also, repairs to these aircraft demand a production process that has the flexibility to be relatively in-situ with the same high-performance output. Materials produced by the cold spray process, a thermo-mechanical powder consolidation technique, meet many of the requirements. In accordance with President Obama’s 2011 Materials Genome Initiative, the focus of this effort is to design customized aluminum alloy powders which exploit the unique behavior and properties of the materials created by the cold spray process. Analytical and computational models are used to customize microchemistry, thermal conditioning, and solidification behavior of the powders by predicting equilibrium and non-equilibrium microstructure and resulting materials properties and performance. Thermodynamic, kinetic, and solidification models are used, including commercial software packages Thermo-Calc, Pandat™, and JMatPro®, and TC-PRISMA. Predicted powder properties can be used as input into a cold spray process impact model to determine the consolidated materials’ properties. Mechanical properties of powder particles are predicted as a function of powder particle diameter and are compared to experimental results.

Les calculs d'équilibres à triphasiques et quadriphasiques sont au cœur des simulations de réservoirs impliquant des processus de récupérations tertiaires. Dans les procédés d'injection de gaz ou de vapeur, le système huile-gaz est enrichi d'une nouvelle phase qui joue un rôle important dans la récupération de l'huile en place. Les calculs d'équilibres représentent la majeure partie des temps de calculs dans les simulations de réservoir compositionnelles où les routines thermodynamiques sont appelées un nombre conséquent de fois. Il est donc important de concevoir des algorithmes qui soient fiables, robustes et rapides. Dans la littérature peu de simulateurs basés sur des équations d'état sont applicables aux procédés de récupération thermique. A notre connaissance, il n'existe pas de simulation thermique complètement compositionnelle de ces procédés pour des cas d'applications aux huiles lourdes. Ces simulations apparaissent essentielles et pourraient offrir des outils améliorés pour l’étude prédictive de certains champs. Dans cette thèse, des algorithmes robustes et efficaces de calculs d’équilibre multiphasiques sont proposés permettant de surmonter les difficultés rencontrés durant les simulations d'injection de vapeur pour des huiles lourdes. La plupart des algorithmes d'équilibre de phases sont basés sur la méthode de Newton et utilisent les variables conventionnelles comme variables indépendantes. Dans un premier temps, des améliorations de ces algorithmes sont proposées. Les variables réduites permettent de réduire la dimensionnalité du système de nc (nombre de composants) dans le cas des variables conventionnelles, à M (M<<nc), et sont déjà utilisées dans certains simulateurs de réservoirs commerciaux. La méthode de réduction proposée par Nichita and Graciaa (Fluid Phase Equil. 302 (2011) 226-233) est étendue à l'analyse de stabilité et aux calculs d'équilibres multiphasiques. A l'inverse des précédentes méthodes de réduction, les variables ne sont pas bornées. La méthode de Newton nécessite une Hessienne définie positive pour pouvoir être utilisée. D'autres méthodes de minimisations sont testées permettant de s'affranchir de cette contrainte; les méthodes Quasi-Newton et Trust-Region qui garantissent une direction de descente à chaque itération. Ces dernières présentent un grand intérêt puisqu'elles permettent de réaliser des pas supra-linéaires (même lorsque la Hessienne n'est pas définie positive) et quadratiques (Trust-Region) ou proches de quadratiques (Quasi-Newton) dans le cas contraire. Un nouveau vecteur de variables indépendantes est proposé (construit afin d'obtenir une meilleure mise échelle du problème) et utilisé au sein d'un algorithme BFGS modifié. De même, une méthode de Trust-Region est développée pour les problèmes de tests de stabilités et d'équilibres multiphasiques. Ensuite, considérant le fluide comme semi-continu, une méthodologie basée sur une procédure de quadrature Gaussienne est proposée pour calculer mathématiquement les pseudo-composants capables de représenter le comportement du fluide. La méthodologie peut être vue comme une procédure de groupement/dégroupement, applicable pour tout nombre de points de quadratures et toute composition de mélange. Dans une dernière partie, un algorithme général pour le calcul d’équilibre multiphasique est présenté incluant tous les algorithmes développés. Ce dernier est testé et validé contre des données expérimentales et de la littérature. Des simulations triphasiques et quadriphasiques d'injection de CO2 démontrent la capacité du programme à traiter un nombre arbitraire de phases. Des simulations de balayages par la vapeur sont réalisées pour des réservoirs montrant d'importantes hétérogénéités. Finalement, une simulation complètement compositionnelle du processus de Steam Assisted Gravity Drainage est réalisée. A notre connaissance, il s'agit de la première simulation de la sorte pour des cas d'applications d'huiles lourdes. / Three to four phase equilibrium calculations are in the heart of tertiary recovery simulations. In gas/steam injection processes, additional phases emerging from the oil-gas system are added to the set and have a significant impact on the oil recovery. The most important computational effort in many chemical process simulators and in petroleum compositional reservoir simulations is required by phase equilibrium and thermodynamic property calculations. In field scale reservoir simulations, a huge number of phase equilibrium calculations is required. For all these reasons, the algorithms must be robust and time-saving. In the literature, few simulators based on equations of state (EoS) are applicable to thermal recovery processes such as steam injection. To the best of our knowledge, no fully compositional thermal simulation of the steam injection process has been proposed with extra-heavy oils; these simulations are essential and will offer improved tools for predictive studies of the heavy oil fields. Thus, in this thesis different algorithms of improved efficiency and robustness for multiphase equilibrium calculations are proposed, able to handle conditions encountered during the simulation of steam injection for heavy oil mixtures. Most of the phase equilibrium calculations are based on the Newton method and use conventional independent variables. These algorithms are first investigated and different improvements are proposed. Michelsen’s (Fluid Phase Equil. 9 (1982) 21-40) method for multiphase-split problems is modified to take full advantage of symmetry (in the construction of the Jacobian matrix and the resolution of the linear system). The reduction methods enable to reduce the space of study from nc (number of components) for conventional variables to M (M<<nc) and are already used in some commercial reservoir simulators. The reduction method proposed by Nichita and Graciaa (Fluid Phase Equil. 302 (2011) 226-233) is extended to phase stability analysis and multiphase-split calculations. Unlike previous reduction methods, the set of variables is unbounded and the convergence path is the same as in conventional methods using the logarithm of equilibrium constants as variables. The Newton method requires a positive definite Hessian for convergence. Other kinds of minimization methods are investigated which overcome this constraint; the Quasi-Newton and Trust-region methods always guarantee a descent direction. These methods represent an interesting alternative since they can reach supra-linear steps even when the Hessian is non-positive definite, and can reach quadratic steps (Trust-Region) or nearly quadratic steps (Quasi-Newton) otherwise. A new set of independent variables is proposed (designed to ensure a better scaling of the problem) for a modified BFGS (which ensures the positive definiteness of the approximation of the Hessian matrix) algorithm and a Trust-Region method is also proposed for the stability-testing and phase-split problems. Subsequently, by assuming the fluid composition as semi-continuous, a methodology based on a Gaussian quadrature is proposed to mathematically compute a set of pseudo-components capable of representing the fluid behavior. The methodology can be seen as a lumping-delumping procedure, applicable to any number of quadrature points and to any feed distribution. In a last part, a general multiphase flash procedure implementing all the developed algorithms is presented, and tested against experimental and literature data. Three- and four phase CO2 injection simulations demonstrate the capability of the program to handle any number of phases. Simulations of steam flooding are performed for highly heterogeneous reservoirs. Finally, a fully compositional simulation of the steam assisted gravity drainage process is realized. To the best of our knowledge, this is the first simulation of the kind for heavy oil mixtures.