Fortunately, process design, and more generally, process systems engineering, has undergone a dramatic change over the last 20 years. During this period many new fundamental and significant advances have taken place. The more or less ad hoc analysis of flowsheets has been replaced by systematic numerical solution techniques that are now widely implemented in computer modeling systems and simulation packages for both preliminary and detailed design. The largely arbitrary selection of parameters in process flowsheets has been replaced by the use of modern optimization strategies. The intuitive development of structures of process flowsheets has been largely replaced by systematic synthesis methods, both in the form of conceptual insights and in the form of advanced discrete optimization techniques.

It is from the perspective of the above advances in process design that this textbook has been written: to teach modern and systematic approaches to design. The emphasis is on the application of strategies for preliminary design, on the systematic development of representations for process synthesis, and on the development of mathematical models for simulation and optimization for their use in computer-based solution techniques. The main aim in learning these techniques is to be able to synthesize and design process flow sheets, understanding the decisions involved in the reaction, separation, and heat integration subsystems, as well as their interactions and economic implications. The applications deal mostly with large-scale continuous processes, although some introduction to multiproduct batch processes is given. Also, while economics is used as the main measure for evaluation, a brief exposure to operability and discussion on multiple criteria (safety, environmental impact) is covered.

The book consists of 22 chapters, organized into four major parts: I: Preliminary Analysis and Evaluation of Processes, 11: Analysis with Rigorous Process Models, III: Basic Concepts in Process Synthesis, IV: Optimization Approaches to Process Synthesis and Design. An introductory chapter is also presented to give a broader view of process design. The textbook is aimed at senior undergraduate and graduate students in chemical engineering. At the undergraduate level it is intended to be a textbook for the senior design course. Chapters 1 to 11 (except 9) could be typically covered in such a course. Chapters 9 and 15 to 17 of Part IV can be used as part of an undergraduate optimization course. At the graduate level, Chapters 9 to 22 and Appendix A can be used as a basis for an advanced process systems engineering course. Chapters 10 to 22 (Parts III and IV) are aimed specifically at a graduate course in process synthesis. Each chapter contains a set of exercises and references to representative publications. Design practitioners who wish to learn about modern design techniques should find this book useful as a reference text.

It is important to note that this book is not meant to be a research monograph. All the material presented here has been developed and taught extensively in courses at Carnegie Mellon University. For instance, a portion of Part I was first developed by Art Westerberg in 1978, and has gradually evolved since then into lecture notes that are currently used in the Senior Undergraduate Design course. Part II was developed first in the early 1980s for a graduate course taught by Art Westerberg on Advanced Process Engineering. Its current form reflects the lecture notes used by Larry Biegler for an advanced undergraduate/graduate level course on computational design methods. Part III corresponds to lecture notes used by Art Westerberg in a current graduate course on Process Systems Engineering. A portion of Part IV was first developed by Ignacio Grossmann in a course on Special Topics on Advanced Process Enginneering course in 1985. In its present form it is being used in the graduate course on Process Systems Engineering. Also note that all the chapters include exercises. Some of these require the use of spreadsheets and modeling systems for optimization (see Appendix A).

The authors would like to acknowledge the many individuals that made this book possible. We express our gratitude to Professor John Anderson for having encour-aged us to undertake the task of writing this textbook. Larry Biegler is grateful to the Department of Chemical Engineering for releasing him of teaching duties for one semester to write this book. Ignacio Grossmann is grateful to the School of Chemical Engineering at Cornell University and to the Centre for Process Systems Engineering at Imperial College for having provided time and financial support for his sabbatical leaves in 1986-1987, and 1993-1994, respectively, in which most of the chapters on Part IV were written. Art Westerberg is grateful to the University of Edinburgh for the time and support he received to prepare portions of this book. The three authors are indebted to the following individuals who have provided us extensive feedback on the book: Dr. Alberto Bandoni, Dr. Mark Daichendt, Professor Truls Gundersen, Dr. Zdravko Kravanja, Dr. Antonis Kokossis, Dr. Guillermo Rotstein, and Professor Ross Swaney. We are also grateful to all our current graduate students at Carnegie Mellon who helped us in the proofreading of the manuscript. Finally, we are most grateful to Dolores Dlugokecki and Laura Shaheen for their help and patience in typing and correcting many of the versions of our manuscript.