Abstract: A system for providing nitrogen enriched air (NEA) from ambient air uses at least two gas separation membranes that are selectively gas permeable for oxygen and nitrogen. The oxygen/nitrogen selectivity and oxygen permeance of two of the membranes are different such that (1) the selectivity of first membrane is less than the second membrane and the oxygen permeance of first membrane is greater than the second membrane, or (2) the selectivity of first membrane is greater than the second membrane and the oxygen permeance of first membrane is less than the second membrane. The system is very compact, is energy efficient, and highly effective for generating NEA. It is ideally suited for mobile, remote and specialized end use applications, such as automotive vehicles, marine vessels, off-shore platform fuel storage and especially for supplying NEA to blanket ullage of onboard aircraft fuel storage tanks.

Abstract: A system for providing nitrogen enriched air (NEA) from ambient air uses at least two gas separation membranes that are selectively gas permeable for oxygen and nitrogen. The oxygen/nitrogen selectivity and oxygen permeance of two of the membranes are different such that (1) the selectivity of first membrane is less than the second membrane and the oxygen permeance of first membrane is greater than the second membrane, or (2) the selectivity of first membrane is greater than the second membrane and the oxygen permeance of first membrane is less than the second membrane. The system is very compact, is energy efficient, and highly effective for generating NEA. It is ideally suited for mobile, remote and specialized end use applications, such as automotive vehicles, marine vessels, off-shore platform fuel storage and especially for supplying NEA to blanket ullage of onboard aircraft fuel storage tanks.

Abstract: Glassy polymeric gas separation membranes are chemically modified throughout the thickness thereof. Such membranes manifest selectivity for a pair of gases which is greater than the intrinsic selectivity of the glassy polymeric material and which is greater than the equilibrium intrinsic selectivity of the chemically modified glassy polymeric material.

Abstract: Fluid separation membranes and modules containing the separation membranes are disclosed wherein the membranes have preselected portions having lower selectivity to the feed fluid mixture; thus permitting the fluid feed mixtures to permeate the membranes in controlled amounts for purposes of sweeping selected permeate fluid away from the non-feed membrane surface.

Abstract: A fluid separation module made up of a cylindrical shell having an outlet end and an enlarged inlet end. A bundle of hollow fiber membranes positioned in the shell extend through a cast tube sheet positioned in the enlarged inlet end of the shell. A flexible, imperforate sleeve is positioned in the shell surrounding the bundle of hollow fiber membranes, with one end of the sleeve being secured to the fiber bundle adjacent to the tube sheet and the other end of the sleeve being secured to the inner surface of the cylindrical shell at the enlarged end at the end thereof to leave a retroflexed, intermediate portion of the sleeve extending down the shell between the shell and the bundle of hollow fiber membranes. A fluid entering the inlet end of the shell inflates the flexible sleeve to occupy all free space between the fiber bundle and the shell and thereby force all of the fluid to pass through the bundle of hollow fiber membranes.

Abstract: The method of recovering unreacted mono-olefinic monomers from an acrylonitrile polymerization slurry containing 30 to 50 weight percent of polymer solids and 70 to 50 weight percent of unreacted monomers wherein the slurry is first diluted with a solvent for the polymer and then fed in series through first and second treatment zones, with each of the treatment zones having a first stage for mixing the slurry with a solvent in vapor form to vaporize some of the unreacted monomers from the slurry and form a polymer solution and a second stage for separating monomer vapors from the liquid polymer solution. Fresh solvent, in vapor form and at an elevated temperature is supplied to the mixing stage of the second treatment zone and the vaporized solvent and unreacted monomers from the separation stage of the second treatment zone are fed to the mixing stage of the first treatment zone. The preferred ratio of solvent to slurry being fed to the mixing stages is 0.8 to 1.2.