Page 76 - The engineering of chemical reactions

60 Reaction Rates, the Batch Reactor, and the Real World

PETROLEUM REFINING

Next, before we proceed to consider flow reactors, we will completely change topics and
discuss two examples: the refining of petroleum and the production of polyester. Our first
purpose is to describe these reactions and the reactors that are used in order to acquaint
students with these very important processes.
Our second purpose in discussing these processes is to indicate that the reactions
and reactors used for these processes have almost mind-boggling complexity. The chemical
engineer is in charge of designing and operating these processes, and we must be aware
of this complexity and see through-it to discover the principles by which these processes
operate (and to fix them if they are not operating satisfactorily).
The following sections will be purely descriptive with no equations except for the
chemical reactions, and even the chemical reactions listed will be highly simplified. As we
proceed through this course, the principles by which these reactors are operated will become
clearer, such that by the final chapter we will have considered most of these reactors and
the principles of their operation in more detail.

Energy sources

The processing of crude oil into gasoline, other fuels, and chemicals has always been the
bread-and-butter employer of chemical engineers. The discipline of chemical engineering
had its origins in producing fuels and chemicals, and these tasks remain the dominant topic
of the chemical engineer.
The energy sources we use are listed in Table 2-3.
The widespread use of coal started the Industrial Revolution, and in the nineteenth
century wood and then coal were the major energy and chemical sources, while whale oil
was our energy source for lighting as lamps replaced candles. Then in the late nineteenth
and early twentieth century petroleum replaced all of these. Now natural gas is becoming
very important, and coal may someday see a revival.
Renewable energy sources such as trees and plants have always had a niche market in
energy and chemicals. In fact, all energy except nuclear energy is ultimately derived from
solar energy in some form or other.

TABLE 2-3
Energy Sources and the Times When They Were Important

Energy source Years dominant
solar, wind, and water
wood always
animal fat <1900
whale oil 170cL1900
coal >1700
crude oil > 1880
natural gas > 1950
nuclear energy >1950
shale oil >1970
tar sands >1970