Process for the recovery of nitrogen-rich gases from gases containing at least oxygen as other component

Claim 1

In a process for the recovery of nitrogen by passing a feed gas containing in addition to the nitrogen, oxygen and trace pollutants through one of two adsorbers, each adsorber containing a carbonaceous molecular sieve for adsorbing the oxygen and trace pollutants, adsorbing the oxygen and trace pollutants from said gas, discharging the treated gas and desorbing the molecular sieve of oxygen and trace pollutants, the improvement for obtaining substantially pure nitrogen gas in a single stage comprising utilizing two alternatingly charged adsorbers, said adsorption and desorption steps being effected by the adsorbers to the same repeated pressure cycle including a pressure continuously increasing up to about 3-10 bar by the feed gas which is charged in an amount of 0.04 to 0.07 Nm 3 /m 3 molecular sieve per second for the adsorption step while simultaneously discharging substantially pure nitrogen from the outlet end of the adsorber and a pressure reduced to about atmospheric or less for the desorption step while the feed gas flow into this adsorber is stopped during the desorption time, the shutting off of said adsorption step from said desorption step being effected when the oxygen content in the nitrogen gas being discharged amounts to 0.1-1.0% by volume whereupon the adsorber is then subjected to the decreased pressure to effect a regeneration of the adsorbent by desorption of the oxygen and trace pollutants therefrom, wherein the adsorption step is being carried out in one of said adsorbers while the desorption step is being carried out in said other adsorber.