Membrane gas separation
As gas separation, the technique is referred to, to separate different gases, for example by means of membranes or by virtue of their physical properties (boiling point / earth).
Linde process
In the Linde process, a gas mixture is pressurized, cooled and relaxed, and this until the individual fractions liquefy sorted according to their boiling point. The Linde process for gas liquefaction requires a positive Joule -Thomson coefficient. Gases such as He must be pre-cooled below the inversion temperature.
Membrane processes
These gases are separated through membranes due to their size and / or their affinity. The achievable purity for oxygen / nitrogen separation by membranes does not reach the extremely high cryogenic Linde process. Is a lower purity or even just the enrichment of a component - such as oxygen in the air - enough, is the membrane process an energy-and cost -saving alternative dar. So a purity of 99.5 % for nitrogen is often sufficient, and there are currently an estimated 30% of the nitrogen requirements covered by the membrane technique. Another application of find membranes in the separation of carbon dioxide and nitrogen / hydrogen. Membranes from multiblock copolymers consisting of polyethylene glycol ( PEG) and polyamide ( PA), are for carbon dioxide quickly and easily permeable, while they have only a very low permeability to nitrogen and hydrogen. These membranes recently developed could be used in so-called " zero-emission power plant ."
Gas centrifuge
Gas centrifuges separate gases using the centripetal force due to their mass differences.
Gas chromatograph
Gases in a gas chromatograph of a sample is separated by absorption / desorption on a flow-through substrate to be analyzed at the end of the column sequentially.
Pressure swing adsorption
Pressure swing adsorption ( PSA English - pressure swing adsoption ) is used in a pair of pressure vessel with granular molecular sieve as adsorbent for air separation about.
Areas of application
- Fuel cell
- Hydrogen separation for energy
- Purification of biogas, landfill gas and natural gas ( removal of CO2, H2S and silanes )
- Nitrogen oxide reduction by nitrogen enrichment ( RWTH Aachen )
- Membrane processes: nitrogen generators, such as those used by way of example for HPLC -MS coupling, operate according to this principle.