Packed bed ion exchange technology stops undue movement during upward flow
The benefits of counter flow regeneration have been established for many years and a number of engineering systems have been developed, including the use of ‘packed beds’ to stop undue movement during the upward flow of either influent water or regenerant chemicals and displacement rinses is well established.
The packed bed design probably offers the simplest solution to holding the bed in place during up flow operation. However, there are many hidden difficulties which may not be apparent to those who have not designed and operated this type of plant.
Packed bed design is still not fully understood despite being installed in many different applications and a two year pilot plant programme to fully explain this technology was embarked upon by Purolite, a ion exchange resin manufacturer with production sites in the USA, Europe and Asia. This study resulted in the development of an advanced packed bed system marketed under the Puropack name and range of resins.
The Puropack system goes beyond supplying the optimum resin for these designs and includes process sizing of service vessels, backwash towers etc, and providing full data covering resin performance (capacity/leakage), minimum compaction flow rates, regeneration conditions, prediction of resin pressure drop and also permitted solids loadings if down flow service is employed. Puropack is almost unique in allowing designs with either up flow service/down flow regeneration or down flow service with up flow regeneration.
Outline engineering drawings are available as well as basic flow diagrams and offer guidance on instrumentation/control requirements, etc, are offered as part of the complete program.
Pilot plant work has shown <0.4micro siemens quality can be routinely obtained over a wide range of operating conditions from a simple two stage Puropack Cation-Anion System.
The narrow and special Puropack grade of resin gives enhanced performance over standard grades and in particular offers, lower pressure drop, higher capacity and lower rinse volumes in many applications where this technology is appropriate.
The full design manual (more than 200pages) gives detailed graphical data across a complete range of Puropack products covering, weak and strong acid cation resins and weak and strong base anion resins including polystyrenic and acrylic resins.
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Purolite International Ltd is based in Llantrisant, Wales. www.purolite.com
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