- 10 August 2006-

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How is the technology different?

IONEX uses a single, multi-port distribution valve, creating a process system for continuous, countercurrent ion exchange. The patented valve distributes different flow streams to several resin cells and determines whether the resin is in an adsorption, a regeneration or a rinsing cycle.

The technology is different from other continuous, countercurrent ion exchange systems that are available in the marketplace. Instead of using a turntable, or carousel, to move the cells around a central valve manifold, the process disc within the IONEX valve rotates around a central axis (figure 1) and distributes the different flow streams to the cells containing ion exchange resin or other adsorption materials. During a full rotation each cell is subjected to an entire sorption cycle.

Adsorptive and ion exchange separation generally comprises a two phase mass-transfer - an adsorption cycle and a desorption cycle - separated by washing or rinsing of the solid phase between these mass transfer steps. The use of shorter and smaller resin beds allow for maximum resin usage.

The mass-transfer zone in a standard ion exchange plant is typically a small section of the actual operating bed length. This small production section, where mass transfer takes place, passes as a transfer zone throughout the bed - from a saturated resin to an unsaturated resin.

To avoid frequent bed regeneration, the content of a vessel is saturated before regeneration takes place. Each regeneration follows a batch sequence. Countercurrent contacting on a continuous basis does not suffer these limitations, because it is not a batch process.

What are the benefits of this approach?

PuriTech's design offers a number of advantages:

. Rigid pipes can be used between the valve and ion exchange vessels, and sealing is greatly simplified, which means only O-rings and gaskets are required
. A simple control unit can be employed because the system does not use a carousel
. A number of user functions can be carried out simultaneously under continuous operating conditions
. Easy access to the valve - the system's only moving part -and the ion exchange vessels, simplifies maintenance procedure
. It is possible to build compact systems based on the technology. The ion exchange cells can be positioned in any desired pattern, providing maximum installation flexibility. IONEX also can be retrofitted to an existing ion exchange system, regardless of where the ion exchange cells are located
. Compared with traditional fixed-bed systems, and depending on the application, IONEX can consume up to 75% less water, while the volume of ion exchange resin required can be reduced by up to 50%, offering significant savings
. Countercurrent fluid flow and recycling, together with uninterrupted process streams, guarantee high levels of recovery. Plants based on IONEX technology could displace some fixed-bed units, (and even some other countercurrent systems currently in use), because they are more cost-effective and require a smaller investment
. In some applications the capital investment on specific projects can be reduced by 20%-40%; this illustrates a like-for-like comparison of a typical carousel system and an IONEX unit - both rated at 40 m3/h
. Further market opportunities for IONEX include replacing 'old' generation multi-port valves
. Various valve configurations and materials are available for specific applications. For example, for a non-corrosive processing environment it is possible to use a standard stainless steel valve head with a polytetrafluoroethylene (PTFE) process disc, while one that is corrosive would require the system to be configured with a polyvinyl chloride (PVC) or polyvinylidenefluoride (PVDF) valve head and an adapted process disc. Hasteloy and Inconel are available for specialist applications.

Conclusion

IONEX could be used in a variety of industries. In the wastewater sector it can treat industrial effluents, removing small traces of toxic substances such as heavy metals and solvents. It also can be used to produce potable and ultrapure water. Other common uses are nitrate, arsenic and perchlorate removal. Other areas in which it may be applied include the electroplating, food processing, pharmaceutical and biotechnology, and petrochemical and chemical industries.

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