Page 16 - Chemical process engineering design and economics

Processes and Process Engineering 3

other uses (20%) [2]. The number of chemicals that are classified as intermediates
is considerable.
Examples of energy processes are the production of fuels from petroleum or
electricity in a steam power plant. A steam power plant is not ordinarily consid-
ered a process, but, nevertheless, it is a special case of a process. The plant con-
tains a combustion reactor, the furnace; pumps; fans; heat exchangers; a water
treatment facility, consisting of separation and purification steps; and most likely
flue gas treatment to remove particulates and sulfur dioxide. Because of the me-
chanical and electrical equipment used, mainly mechanical and electrical engi-
neers operate power plants. However, all chemical plants contain more or less
mechanical and electrical equipment. For example, the methanol-synthesis proc-
ess, discussed later, contains steam turbines for energy recovery. Chemical engi-
neers have the necessary background to work in power plants as well, comple-
menting the skills of both mechanical and electrical engineers.
Bread making, an example of a food process, is almost entirely mechanical,
but it also contains fermentation steps where flour is converted into bread by yeast
[3]. Thus, this process can also be classified as a biochemical process. Another
well known biochemical process that removes organic matter in both municipal
and industrial wastewater streams is the activated sludge process. In this process,
microorganisms feed on organic pollutants, converting them into carbon dioxide,
water, and new microorganisms. The microorganisms are then separated from
most of the water. Some of the microorganisms are recycled to sustain the proc-
ess, and the rest is disposed of.
Aspirin, one of the oldest pharmceutical products, has been produced for
over a hundred of years [4]. A chemist, Felix Hoffmann, who worked for the
Bayer Co. in Elberfeld, Germany, discovered aspirin. He was searching for a
medication for pain relief for his father who suffered from the pain of rheumatism.
Besides pain relief, physicians have recently found that aspirin helps prevent heart
attacks and strokes.
Vitamin C, classified as either a pharmaceutical [5] or a food additive [6],
has annual sales of 325 million dollars, the largest of all pharmaceuticals produced
[7]. Pharmaceuticals, in general, lead in profitability for all industries [6]. Al-
though vitamin C can be extracted from natural sources, it is primarily synthe-
sized. In fact, it was the first vitamin to be produced in commercial quantities [6].
Jaffe [8] outlines the synthesis. Starting with D-glucose, vitamin C is produced in
five chemical steps, one of which is a biochemical oxidation using the bacterium
Acetobacter suboxydans. D-glucose is obtained from cornstarch in a process,
which will be described later.
The personal products industries, which also includes toiletries, is a large
industry, accounting for $10.6 billion in sales in the United States in 1983 [9].
The operation required for manufacturing cosmetics is mainly the mixing of vari-
ous ingredients such as emollients (softening and smoothing agents), surfactants,
solvents, thickeners, humectants (moistening agents), preservatives, perfumes,
colors, flavors and other special additives.

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