Hollow Fibre Membranes
Air separation by means of hollow fibre membranes is a continuous process driven by the principle of selective permeation across the membrane wall. The rate of permeation of each gas present in the feed air is determined by its solubility in the membrane material and the rate of diffusion through the molecular free volume in the membrane wall. These variable permeation rates allow “fast” gases, such as water vapour and oxygen to be separated from “slow” gases such as nitrogen.
The hollow polymer fibres are packed together in a functional unit, called membrane module, which consists of a bundle of several thousand hollow fibres inside a casing made of carbon / stainless steel, aluminium or FRP. Each end of the fibre bundle is embedded in a resin body covering the internal cross-sectional area of the casing so that the feed air is forced into the fibres openings at module inlet and the produced nitrogen is collected at the module outlet. The oxygen enriched permeate will be released at a pressure close to ambient pressure through a radial outlet located on the casing between the two resin bodies. Normally membrane modules are installed in a parallel configuration, so that each module output contributes proportionately to the capacity of the system.
NOXERIOR can offer you a wide range of membrane module sizes in order to offer the most efficient solution at competitive pricing in relation to the nitrogen application and the plant size. The membrane module casings from NOXERIOR can be supplied according to any required pressure vessel design standard.
The compressed feed air will have to be conditioned before entering the membrane module. An adequate air filtration is necessary for a reduction of moisture, particulates, oil and eventual other hydrocarbons present in the supplied compressed air in order to avoid “plugging” of the porous membrane wall.