A Digital-Twin Approach to Distillation Control Education

Process control education often fails to teach students the practical lessons of distillation control. Digital-twin-based training simulations may hold the key to more robust process control education.

Aside from the control of complex reactions, the robust and on-specification control of distillation columns is one of the most challenging aspects of operating modern-day chemical and petrochemical production facilities. Many distillation columns are operated at tighter product specifications and at higher product recovery rates than in previous decades, while stricter environmental regulations mean bottom and side stream specifications must also be tightly managed (1).

Distillation columns can often have challenging operational specifications (2) and/or complex arrangements (3), which makes control, not to mention optimization, of these processes a great challenge; and, with the drive for improved energy efficiencies, they are getting increasingly more complicated (4). As a result, even experienced process operators and engineers need to think about the complex interactions between thermodynamics, internal hydraulics, mass and energy balance limitations, and controller configuration when making operational changes. Considering these shifts and the inevitable loss of experienced operators and engineers, continuing education and competence building are needed in the domain of distillation process control.

However, as many students, as well as practicing engineers, will attest, the way in which process control is taught in many chemical engineering curricula, as well as many industrial continuing education courses, is highly abstract. As a result, students and practitioners have a limited grasp of the influence of process dynamics, as well as steady-state behavior, on the real-time performance of an operating plant. That is, they are unable to apply the theory as it is taught in the traditional way to the real world as they find it (1). Furthermore, those that seem to have mastered the craft of process control can also exacerbate the issue by being unable to effectively communicate with both engineers and operators how the controls affect the process, in both steady state and dynamic aspects. Thus, process control is often perceived and treated as a “black art,” mastery of which is reserved to those who speak a language and describe concepts indiscernible by others!

This article discusses the development of a digital-twin-based approach to continuing education of real-time control of distillation processes. This approach is accessible to engineers in industry, operators, and even managers.

Challenges of process control education...