Possible and actual process layouts

Lines of constant enthalpy tH) Lines of constant pressure 

8 Advantages of the use of near-critical solvents future prospects 

Near-critical extraction can provide an interesting and useful extension to existing extraction techniques in some situations. Very briefly, the advantages in using this technique (not all of which are exploited in existing commercial processes) are as follows  

By control of pressure, a range of selectivities and dissolving powers can be obtained with a given solvent at given temperature. As pointed out by Stahl et aL in 1984 [25], commercial-scale fractionation operations based on this effect are possible future developments. Pilot plant units already exist [1]. 

Because of the diffusivity and viscosity behaviour of near-critical solvents it is to be anticipated that they should give better penetration into pores and matrices and hence faster and more efficient extraction in extractant-film controlled processes than do normal liquid solvents. 

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