A METHOD AND A CYCLIC APPARATUS FOR OBTAINING ENRICHED OXYGEN EFFLUENT PRODUCT BY SELECTIVE ADSORPTION OF NITROGEN FROM AN AMBIENT AIR FEEDSTREAM

摘要

In a cyclic VSA system for air fractionation by selective adsorption of nitrogen from the feed air during an on-stream adsorption period in said cycle in which period an oxygen-enriched primary effluent discharged from the adsorption column is collected in a surge vessel, the duration of the on stream adsorption step is automatically controlled by a sensing device monitoring inventory of gas collected in said surge vessel. In an alternative embodiment the adsorbed nitrogen is withdrawn by vacuum desorption of the column and collected in a second surge vessel, from which second vessel a portion of the nitrogen is subsequently withdrawn for use in rinsing the nitrogen laden column, said second surge vessel being likewise equipped with inventory monitoring means operative for automatically controlling the extent of the rinsing step. Alternately, when nitrogen is collected in a second surge vessel, the system may be operated by inventory monitoring of both surge vessels or only one surge vessel wherein another technique is used to control the other surge vessel.