Patent ID: 6308533
Filing Date: 2001-10-30
Classification: F25J

Abstract:
A process for the low-temperature fractionation of air, comprising:introduced feed air into a first rectification column;withdrawing a transfer fraction of density .rho. in the liquid state from a reservoir within the first rectification column, wherein a liquid level in the reservoir is at a first level h1 and is at a first pressure p1;expanding transfer fraction such that gas bubbles produced on expansion decrease the density of the transfer fraction to the extent that the pressure difference .DELTA.p is sufficient for feeding the transfer fraction to the further process step;feeding the expanded transfer fraction to the further process step at a second, higher level h2 (h2 >h1) and at a second, lower pressure (p2<p1), wherein the difference between the two pressures .DELTA.p=p1-p2 is less than the hydrostatic pressure (Phydr=.rho..multidot.g.multidot.(h2-h1) caused by a liquid column of the transfer fraction between the first level and the second level:.DELTA.p=p1-p2<.rho..multidot.g.multidot.[h2-h1](g: acceleration due to gravity).