How kinetics ruins control, leads to undesirable outcomes, and makes chemical production look like a casino.
At some point in every chemical engineer's education, the term "unit operation" will start to pop up everywhere, and everyone sort of acts like they know what it means—it's those individual blocks on process flow diagrams, right? The "unit operations" idea really comes down to this: if you look at any industrial process with granularity, you'll find that many seemingly different processes in different sectors use the same unit of operation (e.g. a reactor, distillation column, heat exchanger, etc.). The taxonomy was pioneered by Arthur Dehon Little, an American chemical engineer who, in a speech given at MIT in 1916, said: "Any chemical process, on whatever scale conducted, may be resolved into a coordinate series of what may be termed "unit operations", as pulverising, dyeing, roasting, crystallising, filtering, evaporation, electrolysing and so on." But Little's terminology doesn't have to be confined to a chemical engineer's education. All we're really talking about here is the transformation of inputs into outputs at the equipment (aka unit) level instead of at the process level. The process level is usually easy to understand. And some processes, like assembly, are even obvious from an outsider's perspective: car parts go into a factory, and cars go out the factory. There's only one possible outcome, an assembled car, and so nobody is confused about what vehicle manufacturers do in their factories. Ultimately, this is all about the ability to control the outcomes of a given process. If you trace your way back from assembled car to the steel and plastic that it's made of, the operations we need to do shift from macro-level transformations to micro-level transformations. And as we shift in that direction, we simultaneously lose control. That's why chemical companies make so many by-products and co-products. It's like trying to assemble F-150s, but routinely ending up with Miatas. Dealing with unavoidable and undesirable outcomes is not uncommon in other…