Stripping operation water deaeration

Although considerable studies on the use of centrifugal fields in chemical processing have been reported for lab- and pilot-scale operations, little information is public on scale-up criteria for either performance parameters or equipment design. Three examples of commercial use of centrifugal fields are available for review. These include liquid-liquid extraction, water deaeration, and reactive stripping for hypochlorous acid production. 

Prior to deaeration of water in a vacuum column, the dissolved carbon dioxide can be removed using an air stripping operation. Of course, only free CO2 can be stripped, so that CO2 combined in the form of carbonates or bicarbonates must be disassociated by acidification of the water using a nonvolatile acid. 

The steam and cold deaerator makeup water mix in the small stripping section shown in Fig. 22.6. Most of the steam condenses (typically 90 percent) to heat the cold water (120°F) to its boiling point temperature (250°F) at the deaearator operating pressure of 15 psig. The rest is vented to the atmosphere. This vented steam is being used to strip out the residual in the cold-water feed. 

In view of the susceptibility of vegetable oils to oxidation at deodorizer temperatures, the stripping steam must be dry and free of oxygen. This is achieved by deaerating the feed water and generating superheated steam to ensure the availability of dry stream at the deodorizer. The latter requirement is less critical for semicontinuous and continuous operations than for batch ones, where it may have a cooling effect on the oil. Because most boiler systems generate water solids, it is essential that the carryover of these solids into the steam be prevented if mineral contamination of the oil is to be avoided. 

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