Roger Sargent: 1926-2018

We at PSEcommunity.org would like to honour the founder of PSE itself, Professor Roger Sargent, who passed away today. Sargent received BSc and PhDs at Imperial College London, with a PhD thesis in the area of distillation. After spending some time working at Air Liquide, he was recruited back to Imperial College and rose through the ranks as his accomplishments piled up until his retirement. Most famously, he is known as the Father of Process Systems Engineering, having coined the term himself along with Prof. Takamatsu in 1982, and proposing it as a new field of study in a landmark 1967 article entitled “Integrated Design and Optimization of Processes” published in Chemical Engineering Progress (Vol 63 no 9 pages 71-78, 1967).

His key idea was to move the field of process design away from a heuristics-based “ad hoc” strategy in which the expertise and experience of the designer was the key driver, to a more systematic approach in which formal methodologies based on rigorous calculations aided by computers were used. Sargent foresaw the importance of computational power in chemical process design and suggested an approach which in which mathematical models of various types that incorporated key thermodynamic phenomena, mass and energy balances, first principles, heuristics, and experimental results would be used to represent a chemical plant. These models could vary in rigour and be reduced “short cut” models as necessary according to the available computing power. The model could then be incorporated into an optimization framework which would consider appropriate constraints and factor in what made one chemical plant “better” than another. Sargent proposed using various numerical methods and techniques to help solve these problems by converging unit operation or flowsheet models, or moving toward optimal solutions of the larger design problem. Other areas of chemical engineering like process control and operations could also be integrated into the framework through appropriate models and logic. Ultimately, the task of the process systems engineer would be less about designing the chemical process itself, and more about describing the phenomena and characteristics of that chemical process explicitly and mathematically, thereby putting all of the designer’s knowledge into formulating a very well thought out and well-posed problem. Computers using ever-improving numerical methods would take over from there to actually solve it.

This technique is still the bread-and-butter of most PSE researchers today, which is his legacy. Many in our community were readily influenced by him one way or another, and many of us are descendants of his on his academic family tree (he is my academic Great-Grandfather on my post-doc side, so to speak).

We give our condolences to the families, friends, students, and colleagues of Roger Sargent.

For more information, you can find a tribute article from 2016 written by Mike Doherty (UC Santa Barbara), Ignacio Grossman (Carnegie Mellon), and Constantino Pantelides (Imperial College London) here: https://onlinelibrary.wiley.com/doi/abs/10.1002/aic.15425

Thomas A. Adams II

Associate Professor of Chemical Engineering at McMaster University