Chemical process engineering is the study, design, and/or analysis of the methods for producing materials through the control of chemical reactions. Chemical process engineering is used to create consistent, high-quality materials such as beer, gasoline, paint, detergents, pharmaceuticals, and glass under controlled conditions. The methods for producing these materials are divided into several steps, each of which is referred to as a process. Reactants combine, dissociate, separate, or otherwise change during each process to produce products, the desired result, and byproducts that may or may not be useful. To limit non-useful reactions and promote desired reactions, a chemical process engineer must control the conditions of each step.
A group of chemical process engineers designed petrochemical plants, waste-water treatment plants, commercial bakeries, nuclear power plants, and toothpaste factories. These individuals apply knowledge gained from college and graduate-level courses in heat transfer, mass transfer, fluid dynamics, process control, reaction engineering, and engineering economics, among other subjects, to design a plant that will produce a material that can be sold to generate a profit for investors. Chemical process engineering aims to design a plant that produces a good product while also making a profit.
Even if the process is well understood, each chemical factory is designed individually and is a one-of-a-kind creation. Local differences in water quality, permitted discharges, and transportation costs can all affect the design of a plant that was previously built in another location. Individual process steps may or may not be well understood. Small variations in concentration, temperature, or other operating parameters that were not even noticed on the small scale can cause unforeseen and unwanted reactions on the larger scale, which must be mitigated when scaling up the process from a laboratory scale or a pilot plant.
For each process step, chemical process engineering typically provides two options. The first is batch processing in a tank, and the second is plug-flow processing, which involves the reactant flowing through tubes and reacting along the length of the reactor. Each has its own set of benefits and drawbacks, and most processes combine the two.
Chemical engineers are exposed to a variety of standard reactions and processes during their education. In general, a chemical process will include preparatory steps for the individual reactants; reaction steps, which may include the introduction of a catalyst, the bringing together of the reactants, or a change in the conditions of the reactants; separation and purification steps to produce material of a certain quality; and, finally, waste stream and energy treatment and discharge to environmental standards. Biochemical process engineering is the most recent branch of this field, which involves the use of living biological systems, most commonly bacteria, to create products. Despite the fact that this process is not new, as breweries and cheese factories demonstrate, advances in genetic engineering and microbiology have opened up new possibilities for chemical process engineers.