Chemical process engineering is the practice of studying, designing and/or analyzing the means by which materials are produced through the control of chemical reactions. Materials such as beer, gasoline, paint, detergents, pharmaceuticals and glass are all made using chemical process engineering under controlled conditions to create consistent, high quality products. The means by which these materials are made consist of several individual steps, each called a process. During each process, reactants combine, disassociate, separate or otherwise change to form products, the desired result, and byproducts that might or might not be useful. A chemical process engineer must control the conditions of each step to limit non-useful reactions and promote desired reactions.
Facilities such as petrochemical facilities, waste-water treatment plants, commercial bakeries, nuclear power plants and toothpaste factories were designed by a team of chemical process engineers. These people utilize skills gained through college and graduate-level courses in heat transfer, mass transfer, fluid dynamics, process control, reaction engineering and engineering economics, among many others, to design a plant that will produce a material that can be sold in order to yield a return to the investors. Chemical process engineering has the goal of designing a plant that makes a good product as well as a good profit.
Every chemical factory is individually designed and is a unique creation, even if the process is well understood. Local variations in things such as water quality supply, allowed discharges and transportation costs can influence the design of a plant that was built previously in another location. The individual process steps might be known to differing degrees. In scaling up the process from a laboratory scale or a pilot plant, small variations in concentration or temperature or other operating parameters that weren’t even observed on the small scale can cause unforeseen and unwanted reactions on the larger scale that must be mitigated.
Chemical process engineering typically offers two choices for each process step. The first is batch processing in a tank of some kind, and the second is plug-flow processing in which the reactant flows through tubes of some nature and reacts along the length of the reactor. Each has its advantages and disadvantages, and most processes use a combination of the two.
During their education, chemical engineers are exposed to a number of standard reactions and processes. In general, a chemical process will consist of preparatory steps of the individual reactants; the reactions' steps, which might include the introduction of a catalyst, the bringing together of the reactants or a change in the conditions of the reactants; the separation and purification steps to create material of a certain quality; and finally, the treatment and discharge of waste streams and energy to environmental standards. Biochemical process engineering is the latest specialty of this field in which living biological systems — often bacteria — are utilized to make products. Although this process certainly is not new, as breweries and cheese factories demonstrate, gains in genetic engineering and microbiology have created new avenues for chemical process engineers to pursue.