STRUCTURE PACKING SYSTEM FOR REDUCED DISTILLATION COLUMN HEIGHT

摘要

Feed air is passed into a higher pressure column(50) wherein it is separated by cryogenic rectification into nitrogen-enriched vapor and oxygen-enriched liquid. Nitrogen-enriched vapor is passed as stream(54) into a main condenser(55) wherein it is condensed by indirect heat exchange with a lower pressure column(51) bottom liquid. Resulting nitrogen-enriched liquid(56) is passed into the higher pressure column as reflux liquid(57) and into the lower pressure column as reflux liquid(58). Oxygen-enriched liquid is passed in stream(59) into an argon condenser(60) wherein it is at least partially vaporized and then passed into the lower pressure column as shown by stream(61). Within the lower pressure column the various feeds are separated by cryogenic rectification into product nitrogen, which is recovered in stream(62), and into product oxygen which is recovered in stream(63). A side stream(64), comprising from about 7 to 20 mole percent argon with the rest primarily oxygen, is passed from the lower pressure column into a superstaged argon column(52) wherein it is separated into argon-richer fluid and oxygen-richer fluid. The oxygen-richer fluid is withdrawn from the lower portion of the argon column in stream(70), passed through a liquid pump(71) and then passed into the lower pressure column in stream(65). The argon-richer fluid, after being processed in whole or in part in the condenser, is recovered as high purity argon in stream(66) having an argon concentration of at least 98 mole percent and containing less than 5 ppm oxygen. Generally superstaged argon column will have no more than 180 equilibrium stages, and typically will have from 150 to 180 equilibrium stages.