Phase Equilibria In Chemical Engineering

Phase Equilibria in Chemical Engineering covers the practical aspects and the thermodynamic basis of equilibria between gases, liquids, and solids. The importance of, and and interest in these topics over decades has resulted in the development of many different correlations and methods of comparable worth. The author draws upon his many years of experience in evaluating and comparing these alternatives. Professor Walas details the historical background, but focuses on current knowledge for the evaluation of equilibria between gaseous, liquid, and solid phases, and on the chemical engineering processes that involve such phenomena. Knowledge of the amounts and composition of phases that result when processes of transformation stabilize is essential for proper equipment design. To this end, emphasis is placed on finding the numerical results necessary for the design of equipment handling several phases, or the interpretation of such equipment's performance. Therefore, most important points are illustrated through solved numerical examples, as well as problems designed for solution by the reader. And, in addition to numerous computer programs written in BASIC, there are over 800 references to literature, which facilitate pursuit of any topic in further detail. Covers the practical aspects and thermodynamic equilibria between the phases. Compares the different correlations and methods in the field today. Contains numerous examples, illustrations, and references.

Phase Equilibria in Chemical Engineering is devoted to the thermodynamic basis and practical aspects of the calculation of equilibrium conditions of multiple phases that are pertinent to chemical engineering processes. Efforts have been made throughout the book to provide guidance to adequate theory and practice. The book begins with a long chapter on equations of state, since it is intimately bound up with the development of thermodynamics. Following material on basic thermodynamics and nonidealities in terms of fugacities and activities, individual chapters are devoted to equilibria primarily between pairs of phases. A few topics that do not fit into these categories and for which the state of the art is not yet developed quantitatively have been relegated to a separate chapter. The chapter on chemical equilibria is pertinent since many processes involve simultaneous chemical and phase equilibria. Also included are chapters on the evaluation of enthalpy and entropy changes of nonideal substances and mixtures, and on experimental methods. This book is intended as a reference and self-study as well as a textbook either for full courses in phase equilibria or as a supplement to related courses in the chemical engineering curriculum. Practicing engineers concerned with separation technology and process design also may find the book useful.

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

Phase Equilibrium in Mixtures deals with phase equilibrium and the methods of correlating, checking, and predicting phase data. Topics covered range from latent heat and vapor pressure to dilute solutions, ideal and near-ideal solutions, and consistency tests. Molecular considerations and their use for the prediction and correlation of data are also discussed. Comprised of nine chapters, this volume begins with an introduction to the role of thermodynamics and the criteria for equilibrium between phases, along with fugacity and the thermodynamic functions of mixing. The discussion then turns to some of the phase phenomena which may be encountered in chemical engineering practice; methods of correlating and extending vapor pressure data and practical techniques for calculating latent heats from these data; the behavior of dilute solutions both at low and high pressures for reacting and non-reacting systems; and the behavior of ideal and near-ideal solutions. The remaining chapters explore non-ideal solutions at normal pressures; practical methods for testing the thermodynamic consistency of phase data; and the extent to which the broad aspects of phase behavior may be interpreted in the light of simple molecular considerations. This book is intended primarily for graduate chemical engineers but should also be of interest to those graduates in physics or chemistry who need to use phase equilibrium data.

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.

Computational tools allow material scientists to model and analyze increasingly complicated systems to appreciate material behavior. Accurate use and interpretation however, requires a strong understanding of the thermodynamic principles that underpin phase equilibrium, transformation and state. This fully revised and updated edition covers the fundamentals of thermodynamics, with a view to modern computer applications. The theoretical basis of chemical equilibria and chemical changes is covered with an emphasis on the properties of phase diagrams. Starting with the basic principles, discussion moves to systems involving multiple phases. New chapters cover irreversible thermodynamics, extremum principles, and the thermodynamics of surfaces and interfaces. Theoretical descriptions of equilibrium conditions, the state of systems at equilibrium and the changes as equilibrium is reached, are all demonstrated graphically. With illustrative examples - many computer calculated - and worked examples, this textbook is an valuable resource for advanced undergraduates and graduate students in materials science and engineering.

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.

This volume on phase equilibrium engineering (PEE) aims to fill the gap between the books on reactors and separation process design and the textbooks on chemical engineering thermodynamics. The goal is to change the focus from the use of thermodynamic relationships to compute phase equilibria to the design and control of the phase conditions that a process needs. In this way, phase equilibrium thermodynamics is put to work. The main goal of PEE is the design of the system conditions to achieve the desired phase equilibrium scenario that the process at hand requires. In this chapter, the philosophy of phase equilibrium thermodynamic modeling is discussed in the context of process development and chemical plant operation. Typical phase scenarios that are encountered in separation, materials, and chemical process are presented as well as the problem of phase design and the PEE tools.