Abstract: Bundles of hollow filament membranes suitable for use in fluid separation, such as in the separation of air into gases more concentrated in oxygen and nitrogen are made in a cylindrical form and annular cross-section with multiple filaments of each layer lying in generally parallel helical paths at a common angle to the axis of symmetry of the bundle. Continuous lengths of filaments are laid down on the core while same is rotated first in a "forward" sense and the filament lay-down point is traversed from a first end of the core to the second, and then in a "reverse" sense while the filament lay-down point is traversed from the second end to the first. Reversing of the direction of core rotation and filament end-to-end traversal is repeated with said reversing controlled in such a manner that the path of the filament returning from either end to the other is displaced incrementally from that of the filament portion laid down in the immediately preceding traversal.

Abstract: The invention is a process for selectively adsorbing nitrogen from a gas mixture which comprises contacting the gas mixture with an adsorbent that has a moderate nitrogen capacity and a high selectivity for nitrogen over the other components in the mixture. With respect to air separation, improved adsorbents have low O.sub.2 capacity with N.sub.2 capacity at roughly the same level as current adsorbents such as CaA. O.sub.2 VSA computer process simulations have shown the unexpected result that for materials with the same binary isothermal working selectivity, those with lower isothermal nitrogen working capacity are superior O.sub.2 VSA adsorbents, provided that they have a nitrogen working capacity of at least about 0.3 mmol/g.

Abstract: The present invention is directed to adsorptive separation of nitrogen with active adsorbent phases with high N.sub.2 capacity and high heats of adsorption when diluted with inert material at levels ranging from 5% to 80%. The presence of diluent reduces the temperature swings in the adsorbent bed, which increases the utilizable effective N.sub.2 working capacity and decreases the relative amount of O.sub.2 left unrecovered on the active adsorbent phase. The net result is equal or better process performance allowing utilization of a lower amount of active adsorbent phase. Use of a diluent having a higher heat capacity than that of the active adsorbent phase increases these benefits, but dilution effects are beneficial even for diluents with heat capacities equal to or lower than that of the active adsorbent phase.