Page 16 - Distillation theory

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xiv Preface

Until recently, this theory had not advanced to a sufficient extent. Solutions
were only obtained for particular cases. For many years, the author and his col-
leagues, relying on the results obtained by other researchers, have been putting a
great deal of effort into elaborating general methods of the geometric theory to
answer the fundamental questions listed above. An analysis of thermodynamically
reversible distillation, the conception of “sharp” separation, the formulation of
conditions under which distillation trajectories can tear-off from the boundaries
of the concentration simplex, and the conditions of joining of column section
trajectories have been particularly important steps in constructing the geometric
theory of distillation. We have proposed a clear multidimensional geometric rep-
resentation of distillation, which is valid for all types of distillation columns and
complexes, for mixtures of any number of components and azeotropes, and for
all splits. This representation provided answers to all the fundamental questions,
which were previously enumerated. This success encouraged the author to write
the present book.
The optimal design of a distillation plant includes the optimization of the se-
quence of the most economic columns and complexes for separation for a given
mixture (flowsheet synthesis) and optimization of the operating and design pa-
rameters of these columns and complexes (optimal design calculations). Methods
of the general geometric theory of distillation, encoded in software, provide quick
and reliable solutions to both problems. The creation of this book necessitated
the development of DistillDesigner software that allowed us to refine, check, and
confirm the algorithms of optimal designing and also to provide for a significant
portion of illustrations and exercises. The problems are solved neither by conven-
tional “blind” methods nor by trial-and-error methods based on the designer’s
intuition. They are solved in a systematic way, and the solution has a geometric
image so the designer can see that it is really optimal. The creation of the software
product led, in its turn, to a revision of the general statements of the geometric
distillation theory.
Furthermore, the book considers problems that are beyond the framework
of the geometric theory of distillation but are still of importance from both the
theoretical and practical standpoints.
Among these problems is the problem of maximizing energy savings by op-
timizing the type of separation unit and by maximizing heat recovery and the
problem of the maximum yield of the most valuable products in the separation
of thermolabile mixtures (e.g., the maximum yield of the light product in oil re-
fining). Application of optimal design methods based on the general geometric
theory of distillation and use of new, most economic distillation units and separa-
tion sequences bring the practice of separation to a much higher level.
This book is intended for a wide variety of specialists in the design and operation
of separation units in the chemical, pharmaceutical, food, wood, petrochemical,
oil-refining, and natural gas industries, and for those engaged in creating software
for separation unit design. The circle of these specialists comprises software engi-
neers, process designers, and industrial engineers. The software engineer will find
new computational algorithms, the process designer will be provided with a useful