How to Design an Ion Exchange System

Step 4: Atmospheric Degassifier

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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The decision to install an atmospheric degassifier is principally economic. Removing carbon dioxide before it reaches the anion resins will reduce NaOH chemical consumption and this should be balanced against the cost of the degassifier. Generally the economical balance is not in favor of a degassifier for small plants (up to about 10 m³/h or 45 gpm). For larger plants, if the total CO₂ is greater than 50-100 mg/l (ppm), the pay-back time for a degassifier should be short.

Atmospheric degassifiers usually reduce residual CO₂ down to 5 mg/l. In order to have a safety margin for design, a residual value of 10 mg/l CO₂ is recommended.

For systems requiring very low levels of residual CO₂, a vacuum degassifier is used. This reduces the CO₂ to below 1 mg/L.

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