Membrane technology

Modern gas separation membraneThe pivot of the membrane technology is the membrane responsible for the gas separation process. The modern gas separation membrane no longer represents a flat plate or film, but is shaped as hollow fibers.

Membrane separation technologies currently use a hollow-fiber membrane consisting of porous polymer fibers coated with a separation layer. A porous fiber has a complex asymmetric structure, with the polymer density increasing towards the fiber external surface. The application of porous support layers with asymmetric structure allows separating gases under high pressures (up to 6.5 MPa). The thickness of the fiber gas separation layer does not exceed 0.1 µ, ensuring a high relative permeability of gases across the polymer membrane. The existing level of the technological development makes possible the production of polymers with a high selectivity for various gases, and, consequently, capable of deliveringhigh-purity gaseous products. A modern membrane module used for the membrane gas separation technology comprises a removable membrane cartridge and a body. The density of fibers packaging in the cartridge is estimated at some 500–700 square meters per the cartridge cubic meter, which helps to minimize the dimensions of gas separation plants.

Schematic Drawing of Gas Separation Cartridge

Schematic Drawing of Gas Separation Cartridge

The module body has one inlet pipe for feed gas mixture intake, and two outlet pipes for delivery of separated components.

The membrane technology based gas mixture separation utilizes the difference in partial pressures on the external and internal surfaces of a hollow-fiber membrane. Highly permeating gases (e.g. H2, CO2, O2, water vapors, higher hydrocarbons) penetrate the fibers and exit the membrane cartridge through one of the pipes. Less permeating gases (e.g. CO, N2, CH4) exit the membrane modules through the other outlet pipe.

Gas Penetration Rate through Membrane Material
Fast gasesSlow gases
Gas Penetration Rate through Membrane Material
H2OHeH2NH3CO2O2COArN2CH4C2H6C3H8
Membrane Based Gas Separation Process
Schematic presentation of the membrane cartridge operationSchematic presentation of the membrane cartridge operation
Membrane module capacityDependence of the membrane module capacity on the nitrogen purity at various pressures
Diagram of the nitrogen purityDependence of the nitrogen purity on the membrane module inlet and outlet streams ratio at various pressures
Flow Diagram of Membrane Plants Operation
Membrane nitrogen plantMembrane nitrogen plant
Membrane oxygen plantMembrane oxygen plant
Economic Expediency of Membrane Technology Application
Economic expediency of the membrane technology application for nitrogen productionEconomic expediency of the membrane technology application for nitrogen production (N2)
Economic expediency of the membrane technology application for oxygen productionEconomic expediency of the membrane technology application for oxygen production (O2)
Economic expediency of the membrane technology application for hydrogen productionEconomic expediency of the membrane technology application for hydrogen production (H2)
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