Page 28 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

Section 1

Conceptualization and Analysis of Chemical

Processes

The purpose of this section of the book is to introduce the tools necessary to understand, interpret,
synthesize, and create chemical processes. The basis of interpreting chemical processes lies with
understanding the principal diagrams that are routinely used to describe chemical processes, most
important of which is the process flow diagram (PFD). Although PFDs are unique for each chemical
product, they possess many of the same characteristics and attributes. Moreover, the conditions (pressure,
temperature, and concentration) at which different equipment operate are unique to the chemical product
and processing route chosen. In order for process engineers to understand a given process or to be able to
synthesize and optimize a new process, they must be able to apply the principles outlined in this section.
Chapter 1: Diagrams for Understanding Chemical Processes

The technical diagrams commonly used by chemical engineers are presented. These diagrams
include the block flow diagram (BFD), the process flow diagram (PFD), and the piping and
instrumentation diagram (P&ID). A standard method for presenting a PFD is given and illustrated
using a process to produce benzene via the catalytic hydrodealkylation of toluene. The 3-D topology
of chemical processes is introduced, and some basic information on the spacing and elevation of
equipment is presented. These concepts are further illustrated in the Virtual Plant Tour AVI file on
the CD accompanying the textbook.
Chapter 2: The Structure and Synthesis of Process Flow Diagrams
The evolutionary process of design is investigated. This evolution begins with the process concept
diagram that shows the input/output structure of all processes. From this simple starting point, the
engineer can estimate the gross profit margins of competing processes and of processes that use
different chemical synthesis routes to produce the same product. In this chapter, it is shown that all
processes have a similar input/output structure whereby raw materials enter a process and are
reacted to form products and by-products. These products are separated from unreacted feed, which
is usually recycled. The product streams are then purified to yield products that are acceptable to the
market place. All equipment in a process can be categorized into one of the six elements of the

generic block flow process diagram. The process of process design continues by building
preliminary flowsheets from these basic functional elements that are common to all processes.
Chapter 3: Batch Processing
In this chapter, key issues relating to the production of chemical products using batch processes are
explored. The major difference between continuous and batch processes is that unsteady state
operations are normal to batch plants whereas steady state is the norm for continuous processes. The
chapter starts with an example illustrating typical calculations required to design a sequence of batch
operations to produce a given product. The remainder of the chapter is devoted to how best to
sequence the different operations required to produce multiple chemical products using a fixed
amount of equipment. The concepts of Gantt charts, cycle times, batch campaigning, intermediate and
final product storage, and parallel operations are covered.
Chapter 4: Chemical Product Design
Chemical product design is defined to include application of chemical engineering principles to the