EXTRACTION LIQUIDE/GAS
Liquid/gas extraction is based entirely on the relation between the partial pressure of a given gas at the surface of a liquid and the concentration of this same gas in the liquid. This relation is defined by HENRY ‘s Law :
PP = Hx
PP is the partial pressure of a gas on the water surface
H is the constant of HENRY’s law specific to the considered gas and depending on temperature
X is the concentration of gas in water.
HENRY’s law gives us a direct proportionality between the total quantity of gas dissolved in water and the partial pressure of gas. The gas that is in contact with water tends to dissolve in the water, until reaching a point of balance defined amongst other things by the partial pressure and the nature of the gas as well as the temperature. The breaking point of this balance of concentration involves a degasification of the solution or a dissolution of gas:
- If the partial pressure of the gas increases, the gas will tend to dissolve in water.
- If the partial pressure of the gas decreases, the liquid will tend to degas to restore concentration balance.
Due to the hydrophobic property of the PP membrane of the contactors the contactor comes to serve as an interface between two distinct mediums:
- The liquid phase which moves outside hollow fibers (shellside)
- The gas phase which is inside hollow fibers (lumenside)
Membrane prevents the mixing of these phases.
Balance of concentration is broken when depression and/or sweep gas is introduced in the gas phase. A driving force is created, constraining the dissolved gases of the liquid phase to migrate in the gas phase through the membrane (or vice versa).
LIQUI-CEL® membrane contactors have 3 different membranes, according to the implementation medium and the extraction type. None of these membranes show gas selectivity, but they are more or less adapted to various extraction modes:
X50
In water dissolved CO2 is not very stable and can be more easily extracted than other gases (such as oxygen for example). The X50 membrane has porosity from approximately 40% and a wall thickness of approximately 40 µm: a larger contact surface and a smaller membrane resistance results in a more important driving force.
Contact us for more information.
X40
Oxygen dissolves in water in lesser quantities than carbon dioxide, but is much more stable. Extraction conditions have to be increased compared to CO2, by applying a higher vacuum. The X40 membrane has less porosity (25%) and a higher wall thickness (50 µm), conferring a larger structural stability to the hollow fiber.
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XIND
This membrane has approximately the same characteristics and extraction capacities as the X50 membrane. Nevertheless, its resistance to temperature and pressure is less, limiting its field of application to the cold industrial standards not requiring a FDA approval.
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SuperPhobic
If the membranes above are adapted to an implementation in aqueous or similar mediums, it is not the same for the liquids with low surface tension. In fact, the latter will have a wetting effect on the membranes, making them inoperative. The SuperPhobic membrane answers these problems: it is a dense polyolefin with no apparent porosity. Degasification is done by a trans-membrane phenomenon of diffusion (dissolution of gas into the membrane and rejection into the gas phase).Contact us for more information.
our markets
- UPW production (O2 Removal) for electronics
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- Water production (CO2 Removal) prior to EDI
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- Extraction of dissolved gases in the electronics (UPW).
- Extraction of oxygen formed by the destruction of ozone.
- Dissolved nitrogen extraction in the storage tank.
- CO2 extraction to increase the lifespan of the ions exchanging columns.
- CO2 extraction in the EDI/CDI processes.
- Extraction of volatile organic compounds (VOC) from liquids.
- Gas humidification.
- Carbonation, decarbonation & nitrogenization in food industries.
- …
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