What are the common control strategies for distillation columns?

Common configurations: LV (reflux-boilup) - most common, good for high purity; DV (distillate-boilup) - for bottoms purity dominated; L/D-V (reflux ratio control) - handles feed composition changes; Material balance control - controls inventories directly. Composition control: direct (analyzers) or indirect (temperature). Dual composition control requires decoupling or MPC. Pressure control: minimize variation for composition inference. Feed preheating: maximize feed quality control. Considerations: column dynamics (slow), interaction between ends, inverse response (some configurations), and constraints (flooding, weeping).