(113c) The DO’S and DON’TS of Distillation Control — The Practitioner’s Perspective

Product separation using Distillation is still relevant today. Distillation control does not appear to be an issue anymore, judging by the number of recent publications in the field. However, problems with distillation proper operation and control are still latent in the chemical processing industry, a statement that cannot, unfortunately, be supported by any statistics or study, as no production facility would be willing to disclose any information to the public on deficiencies or problems with their operation.
With several distillation columns being operated in manual or with a single composition control, and most of the nowadays efforts in the area of industrial automation being focused on the tools of the fourth Industrial Revolution (4IR), process control appears to have been moved to the back seat; whilst the process control professionals on the ground are not able to get much support as the experts retire or abandon the field, a topic that is outside the scope of this writing.
Given the benefit of its contribution to the practitioner, this paper offers hands-on recommendations on what should and what should not be done, when it comes to distillation control. Recommendations that are based on the author’s years of applied experience on successful delivery of distillation control strategies.
Some of the recommendations included in the paper are: Is there a one-fits-all configuration? When is material balance control the most indicated? What temperature should be used as a composition surrogate? Does Pressure Compensated Temperature always work? Is Model Predictive Control the best approach to Distillation Control?