Calculations for Single-Stage Membrane Separations

Nevertheless, as an example, if the membrane permeabihty to a gaseous component were 

For a gas with a viscosity of 0.01 centipoise, the permeability coefficient K for component i would become 

This is extremely low, since a typical permeable petroleum reservoir formation or rock may have a permeability on the order of as much as 1 darcy or 1000 millidarcies, or as little as, say, 10 darcies or 10 millidarcies, or conceivably even 10 darcies or 1 millidarcy, but which is still many orders of magnitude greater than membrane permeabilities or mobilities. 

The gaseous diffusion coefficient or diffusivity Z), is measured in distance /time (commonly cm /sec), and can be related to, or made equal to, the permeabihty when the units are cleared and made consistent (Hoffman, 2003, p. 37). The exercise is included within the derivations of Example 19.4. 

DERIVATIONS AND CALCULATIONS FOR SINGLE-STAGE MEMBRANE SEPARATIONS 

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