Binary Isothermal Distillation Chris Dekmezian Ilyssa Evans Zach

Binary Isothermal Distillation Chris Dekmezian Ilyssa Evans Zach Levine CBE 162 Process Control Spring 2016 Final Project

Process Description General • A mixture of A & B enter an eight stage isothermal distillation column • Valve VL controls the amount of liquid re-entering the column • Valve VS controls the amount of steam heating the reboiler Disturbances • Feed composition, z. F • Feed flow rate, F Control Objectives • Ensuring x. D ≥ 0. 98 & x. B ≤ 0. 05 by controlling S and L

Flow Control – Characterizing dynamics for VL and VS Step Test for VL to L Step Test for VS to S

Flow Control – PI Controller Output (Tyreus-Luyben Tuned) Controlled Response of L Controlled Response of S

Quality Control – PID Controller Design (Ziegler-Nichols Tuned) Step Test for FC 1 to Top Quality

Quality Control – PID Controller Design (Ziegler-Nichols Tuned) Process Transfer Function (GP, QT 1) Controller Transfer Function (QC 1)

Quality Control – PID Controller Design (Ziegler-Nichols Tuned) Controller Output for Small Setpoint Change Controlled Response of x. D

Quality Control – PID Controller Design (Ziegler-Nichols Tuned) Controller Output for F Controlled Response of x. D

Feed-Forward Controlled Bottoms Composition Feed-Forward Transfer Function

Conclusions • Tyreus-Luyben tuning method was used to design flow controllers, VL to L and VS to S • Higher margins make it more robust than Ziegler-Nichols • PID controller implemented to meet control objective of x. D ≥ 0. 98 • Ziegler-Nichols PID tuning used to ensure better performance • Lead-lag feed forward controller implemented for disturbance rejection • Controller used to mitigate effects of most demanding disturbance, inlet flow rate F • Helps meets control objective x. B ≤ 0. 05

References 1. Mesbah, A. ; Braun, E. ; Nichols, J. CBE 162 Spring 2016 - Final Project. UC Berkeley, 2016. 2. Bequette, B. W. Process Control: Modeling, Design, and Simulation. Upper Saddle River, NJ: Prentice-Hall, 2003.

Appendix A – Simulink Model

Quality Control – PID Controller Design (Ziegler-Nichols Tuned) Controller Output for z. F Controlled Response of x. D