(72u) Optimized Control Strategy of Distillation Column Under Startup and Shutdown

The startup and shutdown operations of a distillation column involve complex heat and mass transfer phenomena in different transient time periods.  Dynamic simulation can be used to study and analyze these dynamic behaviors.  Based on dynamic simulations, column operating procedures and control strategies can be improved to guarantee the operations flexible and reliable. And operation time and energy savings have an appreciable economic significance.

In this study, rigorous dynamic simulations are employed to investigate the startup and shutdown of C2 splitter in an ethylene plant.  First, in the base case, the dynamic model for the column is built with normal control strategy. All the operating procedures are programmed and automated in one rigorous simulation model.  Based on the results in the base case, the control strategy is improved in the optimized case.  Second, dynamic model for C2 splitter is built with optimized control strategy.  Split range control and low select control are applied in this optimized control strategy.  The automation for start-up and shutdown operation is enhanced.  In summary, dynamic simulations performed in this study will help identify operating procedures and control strategies to start up or shut down a distillation column quickly and safely, so as to save plant raw material and energy, reduce operational risks, and thus enhance the industrial sustainability.