Improve The Reliability Of Your Process Models: A Holistic Approach For Chemical Engineers

By Dr. Frank Westad, Chief Scientific Officer, CAMO Software

Chemical engineering is a discipline that to a certain degree relies on deterministic or first principle models. These models may describe flow rates, mass balance, energy and other principal properties of a system. But to quote the famous chemist/statistician George Box: “All models are wrong but some are useful”.

Many of the models or formula found in the literature have certain parameters (or constants) in them, some derived from theory and confirmed by experiments, others estimated from empirical data. One example of the former is the Venturi equation based on Bernoulli’s equation and conservation of energy. As a young student in chemistry where chemical engineering was one subject in the mandatory curriculum, these equations were at that time considered the “truth”. However as one got into the details of a particular subject it was clear that the basic equation did not tell the whole story: there were always assumptions behind those (simple) equations.

In retrospect one realizes that the constants in e.g. fluid mechanics had arisen more from an empirical origin than constants given by laws of nature. Other equations may be valid in a system given a specific operational window, but not in general.