Q & A > Question Details
How can I predict HETP for Sulzer's structured packings (BX, Mellapak 250.Y or EX) when reflux is not total, i.e., when some distillate is taken off (e.g., 10, 20, 50 or 75 %)? Does it depend on the mixture to distill or is it an inherent characteristic of the packing?
15/06/2011 A: Amit Shinde, Sulzer India Ltd, amit-shinde@sulzer.com
HETP of particular packing depends upon the column operating pressure along with the F-factor in the column. F- factor is nothing but the velocity of vapor in the column. HETP generally differs for certain application with the content of water in system. De-rating is done for system with water content.
24/07/2009 A: S Banik, Centre for High Technology, sbdr@rediffmail.com
HETP would vary with class of systems. For hydrocarbons it would be lower compared to alcohol-water. Accurate estimation of HETP for multicomponent system is difficult. Commercial designers would have their proprietary data bank. However for a given system variation of HETP for different packings of same type can be estimated if the value for one version is available. Again BX- made of wire mesh would have lower HETP than Mellapak made of thin sheet for the same surface area.
It is better to generate HETP data in a laboratory scale column with the same system as that of commercial and scale it up for commercial scale.