Page 37 - The engineering of chemical reactions

Chapter 2

! - REACTION RATES, THE

I - BATCH REACTOR, AND

THE -REAL WORLD

n the previous chapter we discussed some topics that chemical engineers need to know
about chemical reactions and chemical reactors. In this chapter we will begin to define
I quantities, formulate and solve mass-balance equations, and consider some examples.
We will then completely change topics and summarize some of the major reactors in the
petroleum and chemical industries.
We will consider only the batch reactor in this chapter. This is a type of reactor that does
not scale up well at all, and continuous reactors dominate the chemical industry. However,
students are usually introduced to reactions and kinetics in physical chemistry courses
through the batch reactor (one might conclude from chemistry courses that the batch reactor
is the only one possible); so we will quickly summarize it here. As we will see in the next
chapter, the equations and their solutions for the batch reactor are in fact identical to the plug
flow tubular reactor, which is one of our favorite continuous reactors; so we will not need
to repeat all these definitions and derivations in the section on the plug flow tubular reactor.
In parallel with these definitions and equations and their solutions, we will describe
in this chapter some examples of important processes in the chemical engineering industry.
This material will initially be completely disconnected from the equations, but eventually
(by Chapter 12) we hope students will be able to relate the complexities of industrial practice
to the simplicity of these basic equations.
Much of this chapter will be a review for those who have had courses in chemical
kinetics. In this chapter we will also review some aspects of thermodynamics that are
important in considering chemical reactors. For students who have not had courses in
kinetics and in the thermodynamics of chemical reactions, this chapter will serve as an
introduction to those topics. This chapter will also introduce the notation we will use
throughout the book.

CHEMICAL REACTIONS

We first describe our representation of chemical reactions. Consider the isomerization
reaction of cyclopropane to propylene,
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