Process and apparatus for the low-temperature fractionation of air

Abstract

The process and the apparatus serve for the low-temperature fractionation of air. Feed air (1) is introduced into a first rectification column (3). A transfer fraction (6, 7) of density ρ is withdrawn in the liquid state from a reservoir (24, 16) within the first rectification column (3), expanded (14, 14a, 18) and fed to a further process step (5, 23). The liquid level in the reservoir (24, 16) is in this case at a first level h1 and is at a first pressure p1. The expanded transfer fraction is fed to the further process step (5, 23) at a second, higher level h2 (h2 >h1) and at a second, lower pressure (p2 <p1). The difference between the two pressures Δp=p1−p2 is less than the hydrostatic pressure (Phydr=ρ·g·[h2−h1]) caused by a liquid column of the transfer fraction between the first level and the second level: Δp=p1−p2<ρ·g·[h2−h1] (g: acceleration due to gravity). The expansion (14, 14a, 18) is carried out in such a manner that the gas bubbles produced on expansion decrease the density of the transfer fraction to the extent that the pressure difference Δp is sufficient for feeding the transfer fraction to the further process step (5, 23).

Dependencies are inferred from the claim text.