V. Pangarkar – Design of Multiphase Reactors (2015)

Автор: V. Pangarkar
Название книги: Design of Multiphase Reactors (2015)
Формат: PDF
Жанр: Химия
Страницы: 535
Качество: Изначально компьютерное, E-book

Details simple design methods for multiphase reactors in the chemical process industries

Includes basic aspects of transport in multiphase reactors and the importance of relatively reliable and simple procedures for predicting mass transfer parameters
Details of design and scale up aspects of several important types of multiphase reactors
Examples illustrated through design methodologies presenting different reactors for reactions that are industrially important

A practicing chemical engineer invariably comes across one or the other type of a
multiphase reactor. The preponderance of multiphase reactors in the chemical process
industry has given rise to widespread research directed toward understanding
their behavior particularly with a view to develop reliable design and scale-up procedures.
The literature is replete with information on various types of multiphase reactors.
Additional information is being regularly generated on various aspects of
multiphase reactors. The efforts in this direction are using increasingly sophisticated
tools like Laser Doppler Anemometry/Velocimetry, computational fluid dynamics,
etc. It will be long before the last word is written on design of multiphase reactors.
Although this fresh information is welcome, the time and money required for it is
disproportionately high, and hence there is a need for simpler, yet theoretically
sound, methods to be applied.
Engineering is the bridge that spans the distance between Art and Science.
Engineering can convert a seemingly intractable problem into a technically approachable
one. Danckwerts (1961) pointed out that the tendency to go more scientific calls
for some caution and that “we ought to produce more powerful teaching methods for
developing both insight and the qualitative analysis of the problem.” The fine balance
between Science and Engineering in any text must be maintained since as another
doyen of chemical engineering, Thomas Sherwood (1961) noted “if perspective is lost
through enthusiasm for scientific and mathematical analyses, an engineer will be less
effective in industry.” The profound statements of these all-time great chemical engineers
are extremely relevant to the present state-of-the art methods for design of multiphase
reactors. Astarita (1997) while agreeing with Danckwerts and Sherwood
argued that the enthusiasm for computational analyses must be separated from simple creative arguments. This book is an attempt to practice what Albert Einstein suggested
Everything should be made as simple as possible, but not simpler.
A number of excellent texts dealing with design of multiphase reactors have been
published (Shah 1979; Ramachandran and Chaudhari 1983; Doraiswamy and Sharma
1984; Trambouze et al. 1988; Westerterp et al. 1988; Harriott 2003). This book
attempts to provide process design procedures for a variety of industrially important
multiphase reactors. The basis of the procedures developed is that whereas the
intrinsic kinetics of any multiphase reaction do not vary with the type of the reactor
used and its scale, the transport parameters (in particular the gas–liquid/solid–liquid
mass transfer coefficients) depend on both the type of reactor and its size. The
intrinsic kinetics can be determined on small scale under appropriate conditions, but
the transport properties need to be specific to the type and size of the reactor. This
book therefore focuses on the development of credible correlations for predicting the
mass transfer coefficients. It relies extensively on the findings of my research group
at the University Department of Chemical Technology (UDCT), Mumbai, in developing
these simple procedures. The tradition of industrial consulting at UDCT, an
institute established by the very desire of the chemical industry, enabled me to understand
the industrial world and its problems. Industrial consulting is a rich source of
valuable research tips. It leads to quality research of industrial relevance combined
with academic punch. This consulting experience over the last 40 years starting with
Late Mr. Chandrakant Khagram (Evergreen Pvt. Ltd., Mumbai) provided me with a
perspective that no classroom learning could have substituted. The concepts of “turbulence
similarity,” “relative suspension,” and “relative dispersion” used in Chapters
6, 7A, and 7B have their roots in this industrial interaction. Theory without practice
is generally considered “dry.” However, experience convinced me that practice
without theory can be disastrous.
This book should be of special interest to process design engineers in the chemical,
fine chemicals, and allied industries. Chapter 7A uses the concepts of relative
suspension/dispersion mentioned earlier for a simple spreadsheet-based design
procedure for the highly complex stirred reactor. Chapter 8 is the first comprehensive
chemical engineering–based treatment of the venturi loop reactor. This reactor has no
serious competition in the fine chemicals industry. Unfortunately, most of the
information pertaining to it is proprietary. The spreadsheet-based design provided in
Chapter 8 should be of special interest to the fine chemicals sector. Chapter 7B is also
probably a similar, first of its type treatment of stirred reactors for cell culture technology,
a frontier area in healthcare. As explained in Chapter 3, specific reactor types
are best suited to specific applications in the chemical industry. The treatment of
various reactors has been arranged into chapters, more or less, in a self-contained
manner. There is, however, some inevitable repetition among chapters, which I hope,
would only serve to reinforce understanding in the respective context. The commonality
in terms of basic design features has, however, not been ignored as evinced, for
instance, in Chapters 7A and 7B.
The chemical and allied industry is continuously evolving. Newer molecules/
processes are being developed. In most cases, the time span between discovery and
commercial exploitation tends to be very short. Therefore, the process designer has to either quickly do a reliable design of a suitable multiphase reactor or use an available
one. Either way, the simplified spreadsheet-based design procedures for the stirred and
venturi loop reactor should find favor with the process design engineering fraternity.
The author is grateful to his students: Aditi Deshpande, Bhushan Toley, Biswa
Das, Dhananjay Bhatkhande, Keshavan Niranjan, Manoj Kandakure, Niteen
Deshmukh, Prasad Pangarkar, Prashant Mandare, Rajendra Prasad, Randheer Yadav,
Sameer Bhongade, Sanjay Kamble, Satish Bhutada, Sri Sivakumar, Venkatesh
Shirure, Yogesh Borole and colleague Professor Sudhir Sawant for help in literature
details, checking of the spreadsheets and overall comments on the flow of information
and readability of the book. Professor Sawant’s support on a personal level at crucial
stages is also gratefully acknowledged. Special thanks are due to Vishwanath Dalvi
and Arun Upadhyaya for regressions of published data. The author gratefully
acknowledges help from Mr. Manoj Modi (Reliance Industries Ltd., Mumbai, India)
during the initial stages of the project on venturi loop reactor. The diligence of Rahul
Bagul and timely corrections by Ajay Urgunde in the artwork is highly appreciated.
Finally, my family, who walked the path and endured my long working hours over
the past 7 years, deserve all thanks.
The author sincerely hopes that the information given in this text will make the
life of the process design engineer easier. The reductionist approach adopted should
appeal to students who wish to unravel the complexities of chemical process equipments
through simple arguments.