| abstract |
A unit capable of simultaneously producing nitrogen of ultra high puritynand liquid oxygen of ultra high purity, is provided. n The inside of a first rectification column 6 includes an upper rectifyingnpart 12, an upper-stage middle rectifying part 13, a lower-stage middlenrectifying part 14 and a lower rectifying part 15. To the upper part 11 above thenupper rectifying part 12 is connected a nitrogen condenser 8. A secondnrectification column 7 includes an upper rectifying part 22 and a lower rectifyingnpart 23, and has a reboiler 25 provided under its lower rectifying part 22. Ultranhigh purity liquid nitrogen is recovered from between the upper rectifying partn12 and upper-stage middle rectifying part 13 of the first rectification column 6,nand ultra high purity liquid oxygen is recovered from below the lower rectifyingnpart 23 of the second rectification column 7. |