Bead Settling During Cation and Anion Resin Separation

Abstract

The production of ultrapure water by ion exchange requires thorough mixing of cationic and anionic resins. In many cases the resins are regenerated requiring bead-type separation prior to chemical treatment with the respective acid or base. Resin separation is predictable based upon backwash conditions, resin properties, and system geometry. An important factor in an accurate model is the drag coefficient relationship. There are numerous models available and the choice can result in significant prediction differences. This article presents data for resin bead fall within a full-depth column and discusses which drag coefficient model is most applicable. The expression by Massey showed the best agreement for this application.

Keywords:

• Ion exchange
• resin separation
• modeling

ACKNOWLEDGMENTS

The authors are grateful to OSU Chemical Engineering Juniors, Tamara Asher, Tyler Osterhaus, Ann Walta, and Ian Adams for providing valuable input and laboratory assistance. The equipment for experimentation was provided by Aquatech, Inc.