How do you approach designing a separation train for a multicomponent industrial stream?

Design methodology: identify all components and target purities, construct residue curve map to identify feasible sequences, evaluate direct/indirect/distributed sequences using heuristics (remove corrosive/hazardous first, most abundant next, difficult separations last). Consider heat integration opportunities (stacked columns, side reboilers). Evaluate hybrid separations for azeotropes or close-boiling systems. Perform economic optimization balancing capital (column size, stages) and operating costs (energy). Use process simulators for rigorous design with sensitivity analysis on key parameters.