Supercritical water heavy oil upgrading, which has the potential for high distillate liquid yields with lower coke formation, is a complex process involving coupled reactions, phase equilibrium and two-phase mixing phenomena. This thesis presents the development of a range of models and tools to simulate such processes at different scales with varying levels of fidelity in describing the underlying physical phenomena. Over the past decade, a number of experiments have been performed in batch reactors to study the upgrading of various heavy oils and crude oil vacuum residua through both oil-phase pyrolysis and reaction in the presence of supercritical water (SCW). While these studies indicate that the presence of SCW can significantly affect the outcomes of the upgrading process, there remains a lack of clarity on whether thermolytic processing in the presence of SCW is indeed significantly beneficial as opposed to pure oil phase pyrolysis and if so, at what operating conditions. In addition, modeling tools coupling the reaction kinetics and phase equilibrium, which can provide deeper insight into the process and the underlying phenomena have been lacking. The first part of this thesis describes the development and application of a two-phase stirred reactor (TPSR) model which couples sub-models for the phase-specific reaction kinetics and multi-component hydrocarbon-water phase equilibrium. Using this model, separate lumped kinetics rate parameters for the oil and SCW phases were inferred that best fit batch reactor experimental data. Analysis of the obtained kinetics parameters reveal the following crucial insights on the chemical pathways involved in the SCW upgrading process (i) the primary coke precursor formation pathway is not suppressed in the SCW phase and (ii) only the secondary pathway towards coke precursors from product distillate species is suppressed in the SCW phase, especially at higher operating temperatures. The TPSR model was then applied to evaluate the performance of heavy oil upgrading using SCW in an oil-water co-flow (visbreaking) Next, an extractive upgrading reactor design was hypothesized to improve high-value distillate liquid product yields and reduce undesirable extrinsic coke formation by removing the distillate products safely out of the reactor in a SCW up-flow thereby preventing their further participation in secondary retrograde combination reactions towards more aromatic coke precursors and low-value gas. The TPSR model was used to evaluate the performance of the SCW extractive upgrading process in terms of distillate liquid yields and coke formation rates for heavy oil vacuum residue over a range of operating temperatures and water flow rates. The predictions demonstrate the significant potential of the extractive upgrading process to achieve the aforementioned objectives. The effect of the extraction rate governed by the interphase mixing time-scale on the product yields and oil-inflow rate for steady-state operation was then quantified. The second part of the thesis describes the development of a computational fluid dynamics (CFD) framework and modeling tool for simulating the coupled two-phase flow and multi-component interphase mass transfer at near-critical/supercritical conditions in applications like SCW heavy oil upgrading. The CFD tool accounts for interface tracking in 2-D/3-D, intra-phase species diffusion, phase-equilibrium limited interphase species transfer and non-ideal thermodynamics. In this tool, the interface is tracked with a conservative sharp interface capturing Volume of Fluid (VoF) scheme using (i) a Piece-wise Linear Interface Reconstruction (PLIC) algorithm (ii) an unsplit geometrical advective flux calculation and (iii) a flux-polyhedron correction. The intra-phase species diffusion is handled using a corrected face-normal gradient calculation accounting for the arbitrary shape and size of phase-specific sub-cells. The interphase mass transfer is computed as a source term consistent with the local phase equilibrium and transport flux constraints at the interface. Finally, the phase-volume change is rigorously accounted for in the discrete pressure equation. The tool was implemented on an open-source CFD platform ensuring compatibility with unstructured mesh information and parallel processing constraints. Finally, the developed CFD tool was applied to determine the two-phase mixing rates in an extractive upgrading configuration for water flow rates of interest. The predictions suggest that the earlier assumption of instantaneous phase-equilibration with respect to the time-scale of reactions relevant in the SCW heavy-oil upgrading process is a reasonable approximation for centimeter-scale reactors. Furthermore, the scaling of the total oil-water interfacial area in the reactor and the average Sherwood number with the water inlet velocity and oil-water interfacial tension were established, providing insight into ways to manipulate the two-phase mixing rate to enable control of the extractive upgrading process at higher operating temperatures.

This book collects the slides prepared for the course of Advanced Engineering Thermodynamics (Master of Science in Mechanical Engineering) and those for the course of Multiscale Modelling and Simulation of Molecular and Mesoscopic Dynamics (PhD Program in Energetics), taught in English at Turin Polytechnic. Here, we provide a broad overview on the different topics taught in our classes. Even though not all topics are presented in the same class, students should be able to more easily reconstruct the connections among different phenomena (and scales), build their own mind map and, eventually, find their own way of deepening the subjects they are more interested in. Several engineering applications have been included. This helps in stressing that very different phenomena are described by transport theory and obey the same underlying fundamental laws of engineering thermodynamics. Detailed tutorials are reported, based on open-source codes for the laboratories (Gromacs, Palabos, OpenFoam and Cantera).

In this chapter, the basic methodologies of phase equilibrium engineering are introduced through the systematic analysis of several case studies. Some of the thermodynamic tools that have been presented in the previous chapters are applied to illustrate how the phase and conceptual process design of complex engineering problems can be tackled from a phase equilibrium engineering approach. In all the case studies, the first step is to consider in great detail the properties of the process feed, the components, their physical properties, concentrations, and molecular interactions. This information is then used for the selection of thermodynamic models, a suitable technology, pressure, temperature, and compositional operating boundaries. It is shown how the mixture composition and the process goals and specifications determine the process scheme and the unit thermodynamic sensitivity. In addition, the importance of the mixture composition is highlighted in combination with the energy and material balance in the case study for the selection of the desirable natural gas cryogenic technologies. The use of a pressure versus temperature drawing board is used to plot the process trajectory and the mixture phase envelopes from the initial conditions to the key phase engineering design problem. Moreover, the phase design provides also a sound basis for the process initial specification and computer simulation. As another example of phase equilibrium engineering, the heat integration in a complex process is solved by the application of the Gibbs phase rule to the LLV equilibria of a ternary mixture.

Traditionally, the teaching of phase equilibria emphasizes the relationships between the thermodynamic variables of each phase in equilibrium rather than its engineering applications. This book changes the focus from the use of thermodynamics relationships to compute phase equilibria to the design and control of the phase conditions that a process needs. Phase Equilibrium Engineering presents a systematic study and application of phase equilibrium tools to the development of chemical processes. The thermodynamic modeling of mixtures for process development, synthesis, simulation, design and optimization is analyzed. The relation between the mixture molecular properties, the selection of the thermodynamic model and the process technology that could be applied are discussed. A classification of mixtures, separation process, thermodynamic models and technologies is presented to guide the engineer in the world of separation processes. The phase condition required for a given reacting system is studied at subcritical and supercritical conditions. The four cardinal points of phase equilibrium engineering are: the chemical plant or process, the laboratory, the modeling of phase equilibria and the simulator. The harmonization of all these components to obtain a better design or operation is the ultimate goal of phase equilibrium engineering. - Methodologies are discussed using relevant industrial examples - The molecular nature and composition of the process mixture is given a key role in process decisions - Phase equilibrium diagrams are used as a drawing board for process implementation

In previous chapters, we have seen the fundamental criteria for phase equilibria and how the phenomenological phase behavior and separation technology of real mixtures are determined by their constituent molecular interactions. Our purpose in this chapter is to present the properties of fluids and the models for the prediction of thermodynamic properties and phase equilibria. These models are classified as predictive models using only pure component properties and semiempirical models based on a molecular thermodynamic approach. Finally, the chapter highlights the importance of the class of mixture and molecular interactions of its components in the selection of thermodynamic models for phase equilibrium calculations.

This work provides coverage of experimental and theoretical procedures for vapour-liquid equilibria (VLE). A survey of the different models and approaches in recent literature enables the reader to choose the appropriate action.

Faculties, publications and doctoral theses in departments or divisions of chemistry, chemical engineering, biochemistry and pharmaceutical and/or medicinal chemistry at universities in the United States and Canada.