To describe in one sentence what a Chemical Engineer
does is a sheer
impossibility, as it is one of the most diverse
However, the description in my Webster's
at least forms a
nice introduction to the traditional
field of Chemical
Engineering (Chem. Eng.):
The branch of engineering that deals with the manufacture of chemicals
on a large scale, esp. with the design and operation of the plan and
To clear up one misconception: chemical engineering is not
chemistry although it originated from this discipline. Also, chemical
engineering has an overlap with chemistry and other disciplines such as
mechanical engineering, materials science, and physics.
At the end of the nineteenth century, the industrial revolution was
in full swing in Europe. Germany was a major center for the production of chemicals, such as explosives,
dyes, drugs, and metals. Plants were operated by
mechanical engineers and industrial chemists.
Around that time, the United States only had a very limited
chemical industry, and relied mainly on the import of chemicals from
Europe. But in the years leading up to World War I, the US was cut off
almost completely from European imports, and this triggered the rise of
the chemical industry in the US. There were only few chemists in the
US, most of them working in academic laboratories. These chemists were
more comfortable with test-tubes, erlenmeyers,
and beakers and had no experience with large scale production
processes. On the other hand, American mechanical engineers did not have
the proper training in chemistry to take on a leading role in the
As a result, the fundamental skills for designing and operating
chemical plants were first formulated at MIT around 1910, and were further developed to what would
become known as chemical engineering. These early chemical
engineers postulated the concept of breaking down a chemical process
into physical operations that they called Unit operations, a
term that is used up to this day. Typical unit operations are
distillation, evaporation, filtration, heat transfer. As the
chemical industry and the chemical processes themselves became more
complex, a second classification for these type of operations was
suggested: the Unit processes. Typical unit processes are oxidation,
sulfonation, nitration, hydrogenation, chlorination, etc.
The chemical industry or Chemical Process Industries (CPI) as it
is commonly called have grown to an immensely diverse field, affecting
everyone's lives. Chemical engineers play a vital role in this field,
serving as designers, consultants and operators of chemical plants.
Chemical engineers also play major roles in research and development,
and on the business side of the industries: forecasting demands,
consulting on product use, and marketing. The chemical engineer is truly
a polymath in the world of the engineering sciences.
The diversity of the discipline is reflected in the variety of the
academic curriculum. Following are some of the courses that the
prospective chemical engineer will encounter:
- Mathematics: the swiss army knife of the chemical
engineer. One cannot study Chem. Eng. without a thorough knowledge of
mathematics. However, the focus is very much on applied
mathematics. For instance, differential
equations are essential for solving problems related to heat
transfer, mass transfer. Numerical analysis is important for
process design calculations. Statistical analysis is often used for
design of experiments and process failure analysis.
- Chemistry: so Chem. Eng. is not chemistry, but you
must have a solid basis in many branches of chemistry: general, analytical, physical, inorganic and organic
chemistry. My inorganic chemistry text book was one-thousand pages with
reaction mechanisms, nomenclature, and formulas; we finished it in one
semester. On top of that, the curriculum requires extensive practical
- Thermodynamics: not only the thermodynamics of gases, but
also that of liquids, since many chemical reactions yield liquid
products and side products.
- Separations: in this course, the student learns about multi-stage
operations, such as distillation, extraction, evaporation. These
processes play an essential role in the CPI.
- Heat Transfer: An essential course for the design of chemical process
equipment: reactors, heat exchangers,
and condensers. All forms of heat transfer (convection,
conduction, radiation) are studied.
- Mass Transfer: this course is another fundamental course,
because it plays an important role in chemical reactions, and the way
the reactions are executed (e.g. diffusion processes).
- Fluid Mechanics: flow through pipes, orifices, etc. The CPI
deals mainly with fluids (whether that being gases or liquids).
Fluid mechanics is a method to describe and quantify the flow of
- Reactor Design: say, we have a reaction of a -> b. Or a -
> d + u1 + u2 +..., where d is a desired product, and
u is an undesired sideproduct. What is the ideal size for a
chemical reactor for a certain flow rate, how much heat do we need to
add or remove to gain the best yield, conversion, and a minimal
amount of side products? A batch reactor or continuous? What happens
to a steady state when the temperature, pH, or concentration is
- Process Design: this course focuses on the design of entire
chemical plants, or process lines. All the required equipment is
evaluated based on performance and costs. For instance, a reaction could
be done at low temperature and low conversion, or at high temperature
and high conversion. The former would be cheaper, but requires
additional costs for separation of reactants and products.
Thus, the overall costs of the latter may be cheaper.
- Process Control: this course deals with maintaining process
parameters, such as temperature, pressure, pH, concentration etc.
Typically, these are feedback processes: we measure a temperature (an
output signal), and based on this, we add or remove heat to the reactor
(an input). Small deviations from the setpoint can have disastrous
effects, such as an explosion of the reactor.
- Many other courses: there is simply not enough space to list
all these courses in detail, but a few I have been exposed to include:
Technical drawing, biotechnology, plastics, environmental
engineering, computer programming, economics, mechanical
A typical chemical engineering job would be to take a discovery from
a chemical laboratory, and turn it into a commercial scale process.
Chemists work on small scales using test tubes, small batch reactors,
and erlenmeyers. The chemical engineer works with very large, expensive
equipment: their reactors can hold 1000 to 10000 gallons or more.
Translating a small scale process to these huge proportions is not a
trivial task. And the associated costs are tremendous: the capital
investment for one single process sometimes exceeds $100 million.
But chemical engineering has expanded to many non-traditional
fields. For instance, the Chem. Eng. department of my school does
research on aerosol droplet formation, catalysis and surface
science, imaging bacteria and biopolymers using atomic force
microscopy, nanostructured materials, and fuel cells.
Chemical engineers will continue to expand into fields that
traditionally belong to other engineering disciplines, as well as new
disciplines. But technology keeps getting more and more complex, and
many of today's challenges can only be solved by interdisciplinary teams
of scientists and engineers. With their diverse skill sets, chemical
engineers will maintain their leading role in the development of advanced technology.
Chemical Engineer's salaries are among the highest of all engineering
disciplines (but I'm deep in the red figures). Because of
the wide diversity of the field, there has been an increasing demand for
Chemical Engineers, although the market has also known its ups and
William L. Luyben and Leonard A. Wenzel, Chemical Process
Analysis - Mass and Energy Balances, Prentice-Hall, 1988.
George T. Austin, Shreve's Chemical Process Industries, McGraw-
The professional society for chemical engineers in the US is called American
Institute of Chemical Engineers (AIChE). Their webpage is at: