This branch of engineering is concerned with the design, construction, and management of factories in which the essential processes consist of chemical reactions. Because of the diversity of the materials dealt with, the practice, for more than 50 years, has been to analyze chemical engineering problems in terms of fundamental unit operations or unit processes such as the grinding or pulverizing of solids. It is the task of the chemical engineer to select and specify the design that will best meet the particular requirements of production and the most appropriate equipment for the new applications.
With the advance of technology, the number of unit operations increases, but of continuing importance are distillation, crystallization, dissolution, filtration, and extraction.
In each unit operation, engineers are concerned with four fundamentals:
(1) the conservation of matter;
(2) the conservation of energy;
(3) the principles of chemical equilibrium;
(4) the principles of chemical reactivity.
In addition, chemical engineers must organize the unit operations in their correct sequence, and they must consider the economic cost of the overall process. Because a continuous, or assembly-line, operation is more economical than a batch process, and is frequently amenable to automatic control, chemical engineers were among the first to incorporate automatic controls into their designs.