What is Chemical Engineering?

Recently, one of my nephews asked me what Chemical Engineering was.  I told him the usual story that Chemical Engineer was the profession that made the stuff that runs the modern world.  While that may be true in that we are in most of the remaining major heavy industries (think refining – including biorefining – as well as oil/gas and chemicals) in America, there is something more fundamental that got me to thinking about Chemical Engineering education.

Something tends to get lost in the academic world.  Academic work lays the foundation as to the things that Chemical Engineers do, but almost entirely focuses on the theoretical.  We have educated a whole generation of engineers who believe that one can calculate anything, and the math is reality.  What a shock it must be to the new grad during his (or her) first job that not everything can be broken down into equations, and many simplifying assumptions must be made.

Theory is important – it is important to know why things are supposed to work, but it is equally (if not more) important to be able to reduce the theory to practice.  Sadly, these are things that are generally taught in schools, one must learn them in the actual practice of one’s chosen profession.

But, back to the main topic – What is Chemical Engineering?  After much thought and pondering, I would propose a simple definition:

Chemical Engineering is the manipulation of matter by managing energy.

 While the above statement may appear to put Chemical Engineers above other engineering disciplines, that is not my intent.  Other types of engineers tend to focus on the energy side with matter being used as a means to their ends.  For example, a Mechanical Engineer may be an expert in heat transfer equipment, but he uses materials of construction and heat transfer media to effectively manage that energy.  However, the matter is not changed, except perhaps by phase change from vapor to liquid or vice-versa.  Other examples will become apparent with some thoughtful consideration.

 The proposed definition looks at both matter and energy.  During the undergraduate career, the first two years are mainly used to fill the toolbox – basic physics, chemistry, and mathematics are the typical grind.  There are a few courses that begin to get in to the specifics of the chosen major, but those generally do not happen until typically late sophomore year.  Physics, Chemistry, and Mathematics are the foundation of all that is to follow.  These courses teach the fundamental rules of how the engineer’s universe operates.  Physics is about energy, Chemistry is about matter; Mathematics ties the two together.

 Chemical Engineers usually take a course we refer to as “Heat and Mass Balances 101”; a first attempt to tie Physics and Energy together.  It is typically not taught that way.  The course reinforces the concept of the laws of energy and mass conservation in terms of black boxes.  Make the balances work, and you get an “A”.

 The transport trilogy – Fluid Mechanics, Heat Transfer, and Mass Transfer – are tools to assist you in moving bulk matter from point A to B, managing energy transport, and moving mass on the molecular level between streams or phases.  These courses are the basis for equipment design – pumps and compressors, heat exchangers, and separations equipment.  Machines for manipulating matter by managing energy.

 Thermodynamics, the basic course all engineers take is an extension of the chapter out of the physics book.  Carnot cycles, heat pumps, enthalpy and entropy are poorly explained in dry detail by professors who really could not care less about the subject (I remember one professor who wanted to do such a bad job of teaching the course he would not be saddled with it again).  But Thermo is the first true energy management course one encounters.

 Similarly, Organic Chemistry was the first matter manipulation course a Chemical Engineer is exposed to.  Unfortunately, the course is taught by a Chemistry professor generally to Chemistry students, and unless you are really lucky, is simply a course of rote memorization, remembering reaction names and obscure reaction mechanisms but never with a larger goal in mind.  After you learn it, you quickly forget most of it if you are not majoring in Chemistry.

 Chemical Engineering (Equilibrium) Thermodynamics gets to the raison d’être of Chemical Engineering.  It even has “Chemical Engineering” in its name.  This subject is all about how to manipulate matter by managing energy.  Granted, the matter manipulation is manipulating the state of matter (liquid to vapor and vice-versa) and its composition, by managing the application of energy sources.

 Physical Chemistry is another melding of Physics and Chemistry, but the focus is more on matter manipulation – it is the first true exposure to reaction rates and further builds on equilibrium thermodynamics.  Here, we learn the molecular mechanisms of how matter is transformed through chemical reaction and what role energy plays in the transformation.

 Process Control as is currently taught is an anachronism.  Using Laplace transforms to model a system and using theory to tune controllers is something I have not seen done in 25 years of professional practice.  Students would be far better served by learning about the basics of sensor technology and how control valves work, not to mention how typical control loops are designed in the real world.

 Probably the best example of synthesis of the definition is the course involving Chemical Reactor Design.  In this field, you need to meld Chemical Engineering Thermodynamics, Physical Chemistry, Fluid Mechanics, Heat Transfer, and Mass Transfer.  In addition, you are introduced to Residence time Distribution (Mixing) theory and forced to integrate all of these disciplines into one unified whole.

 It is the ultimate embodiment of the phrase “Chemical Engineering is the manipulation of matter by managing energy”.