Process for recovering volatile organic liquids

Energy saving process for substantially quantitatively removing and recovering a volatile, organic, water-immiscible wetting liquid from a solid material which is wet therewith, which process comprises:

• a. contacting the wet solid material with superheated vapor of a volatile, organic, water immiscible stripping liquid to vaporize the wetting liquid and produce a mixture comprising superheated stripping liquid vapor and wetting liquid vapor, said stripping liquid having a specific heat less than about 0.6 calorie/gram/.degree. C. at about 250.degree. C. and a latent heat of vaporization less than about 100 calories/gram, said stripping liquid vapor being at a temperature above the boiling point of the wetting liquid and said contacting being carried out in the absence of a substantial amount of gas which cannot be condensed in (d);
• and thereafter
• b. contacting the wet solid material with the vapor mixture produced in (a), while maintaining constant in the system the amount of superheated vapor of stripping liquid, until the solid material is substantially free of wetting liquid and contains organic vapor on its surfaces and/or occluded in its interstices, said maintaining of the amount of superheated vapor of stripping liquid being effected by removing organic vapor in an amount equivalent to the organic liquid vaporized from the wet solid material in (a) and in this step;
• c. displacing the solid-containing organic vapor of (b) with dry steam, which is at a temperature sufficient to avoid substantial condensation thereof on the solid material, to produce a mixture of organic vapor and steam;
• d. condensing the mixture of organic vapor and steam from (c) to produce a liquid, organic water-immiscible phase and a liquid water phase, and thereafter separating the two phases;
• and
• e. recovering solid material which is substantially free of wetting liquid, stripping liquid and vapor of wetting liquid and stripping liquid.