PRODUCTION OF ULTRAHIGH-PURITY OXYGEN - A DISTILLATION METHOD FOR THECOPRODUCTION OF THE HEAVY KEY COMPONENT STREAM FREE OF HEAVIER IMPURITIES

Use of a side stripper for the coproduction of the heavy key component stream free of undesirable heavier impurities has been suggested. A s ide stream containing the heavy key component is withdrawn from a colu mn at a location that is sufficiently above the feed such that it is e ssentially free of the undesired impurities. This side stream is then distilled in a side stripper to remove lighter components. From a give n feed, this method is capable of coproducing a significant fraction o f the heavy key component with extremely high purities and with minima l additional energy usage. Coproduction of ultrahigh-purity oxygen, co ntaining only ppb level impurities, along with standard-grade oxygen ( 99.5%) is presented. In comparison with earlier techniques, this metho d of distillation is simpler and more efficient and uses less equipmen t while maintaining a high recovery of oxygen from air.