Process for obtaining nitrogen from air or nitrogen-containing gases by pressure swing adsorption on carbon molecular sieves

PCT No. PCT/EP90/02140 Sec. 371 Date Mar. 4, 1992 Sec. 102(e) Date Mar. 4, 1992 PCT Filed Dec. 10, 1990 PCT Pub. No. WO91/08823 PCT Pub. Date Jun. 27, 1991.Process for obtaining nitrogen from air or nitrogen-containing gases by pressure exchange adsorption and desorption on two alternately operated adsorbers filled with carbon molecular sieves, whereby air is passed through the adsorber so that the oxygen is adsorbed and enriched nitrogen is obtained, while at the same time the other adsorber is regenerated by pressure relief, whereby in a first carbon molecular sieve layer (on the air intake side) of the two adsorbers, making up 1/20 to 1/2 of the entire carbon molecular sieve layer, a carbon molecular sieve A is introduced which serves simultaneously for the adsorption of the residual humidity and gas separation, and that in a second (on the air-outlet side) carbon molecular sieve layer a carbon molecular sieve B is introduced serving exclusively for gas separation, and that the carbon molecular sieve A has a relative volume of 3.0 to 3.4 and the carbon molecular sieve B has a relative volume of 2.3 to 2.95.