Dow Water & Process Solutions

How to Design an Ion Exchange System

Step 3: Chemical Efficiencies for Different Resin Configurations

Steps:

Step 1: Regeneration System Selection
Step 2: Selection of Layout and Resin Types (Configuration)
Step 3: Chemical Efficiencies for Different Resin Configurations
Step 4: Atmospheric Degassifier
Step 5: Resin Operating Capacities and Regenerant Levels
Step 6: Vessel Sizing
Step 7: Number of Lines
Step 8: Mixed Bed Design Considerations

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Due to differences in the regenerability of strong and weak functionalized resins, the configurations described in "Selection of layout and resin types (configuration)" will have different chemical efficiencies. The chemical efficiency of regeneration (also known as stoichiometry) for an IX resin is defined as:

Chemical efficiency =	Amount regenerant chemical added (eq/l)	x 100%
	Resin operating capacity obtained (eq/l)

As the resin usage of the regenerant chemical is non-ideal, the chemical efficiency is always >100%. The efficiency therefore becomes worse as the value increases. The following table gives typical regeneration efficiencies for different resin types and combinations in co-current and counter-current regeneration systems.

Resin type/configuration	Regeneration system	Typical Regeneration Efficiency (%)
Strong Acid Cation	Co-current HCl	200-250
	Counter-current HCl	120-150
	Co-current H2SO4	250-300
	Counter-current H2SO4	150-200
Weak Acid Cation		105-115
Weak Acid + Strong Acid Cation		105-115
Strong Base Anion Type I	Co-current	250-300
	Counter-current	140-220
Strong Base Anion Type II	Co-current	150-200
	Counter-current	125-140
Weak Base Anion		120-150
Layered Bed Anion		120-130

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