What steps are involved in sizing a distillation column?

Distillation column sizing involves: (1) Thermodynamic modeling - select VLE model, validate against data. (2) Stage calculation - determine minimum stages (Fenske), minimum reflux (Underwood), actual stages (rule: 1.2-1.5 x minimum at 1.2-1.5 x minimum reflux). (3) Feed location - optimize for energy. (4) Hydraulic design - column diameter from flooding correlation (Fair or similar), tray or packing selection based on system. (5) Internals design - tray spacing (typically 24 inch), downcomers, weirs for trays; HETP and bed depth for packing. (6) Condenser and reboiler sizing. (7) Control scheme development. Simulation provides heat duties and profiles; vendor finalizes mechanical details.