Columns for Binary Separations

In one parametric study, six different designs (Fig. 22) were compared (Blakely, 1984). Design 1 was the single-column reference case. Design 2 consisted of a high-pressure and a low-pressure column. The feed was split and fed to both columns in parallel. Both columns performed the same sharp separation, producing pure products. The condenser of the high-pressure column was the reboiler of the low-pressure column. 

In Design 5, both columns were operated at the same pressure. However, the first column produced a pure low-boiler distillate but a mixed underflow, thus allowing the use of a less expensive utility. The mixed bottoms was then com- 

Sloppy First Bottom Split Sloppy First Bottom Split Sloppy First Bottom Split 

Second Column Pressurized Two Steam Pressures First Column Pressurized 

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