Distillation under High Pressure: A Behavioral Study of Packings



The present study deals with the pressure effect (1 to 10 · 105 Pa) on the hydrodynamics and efficiency within packed column distillation. Three kinds of packings are used: Raschig rings and Berl saddles as random packing, and Sulzer Mellapak 250 Y as structured ones. The hydrodynamic study concerns pressure drops, maximum column capacity, and the efficiency, which is characterized by the study of HETP (Heigh Equivalent to one Theoretical Plate). The results obtained show that pressure has a great effect, not only on flooding but also on efficiency. Indeed, when the pressure increases, the operation range increases for the three packings and the HEPT is also decreased. The Marangoni effect was also studied while using for the same packing, three different binary mixtures (positive, neutral, and negative according to Marangoni). The observations made on these three systems, for pressure drops and efficiency, remain valid when the pressure increases up to 10 · 105 Pa.