Process and equipment for the treatment and recovery of solvent vapors by recycling on active charcoal

Claim 1

A process for the treatment and recovery of solvent vapors contained in air or in another gaseous fluid, wherein the air or the gaseous fluid containing the solvent vapors is treated in an equipment comprising: (A) one or more adsorption-desorption assemblies or casings (3) containing active charcoal in fiber form in the form of a bed (5) made up of superposed layers of active charcoal fibers, said bed being arranged between two metal grids held by a metal frame, forming a support-frame (4a) containing said active charcoal fibers, one or more of said support-frame(s) being arranged in a square or rectangular drawer (4) formed by a frame-work supporting the support-frames containing said bed of layers of active charcoal fibers, said support-frames being provided with removable electrical resistors (6) the ends of which are fastened onto one of the sides of the framework; and (B) a system for recovering the solvents comprising: (a) means for converting the adsorbed solvents into vapor form; (b) means for condensing the solvent vapors and, if present, water vapor; (c) means for separating the condensed solvents from the water originating from the water vapor present in the gaseous discharge to be treated; and (d) means comprising conduits, air shutters and valves so as to permit circulation of the fluid in a closed circuit through assembly (A) and system (B), said process comprising three stages, (1) in a first adsorption stage, passing air or the gaseous fluid containing the solvent vapors at ambient temperature through the adsorber (3) containing superposed layers of active charcoal fibers (5) forming a bed, in a support-frame (4a) arranged in a removable drawer (4) above removable electrical resistors (6); adsorbing said solvent vapors onto said active charcoal fibers and discharging the air or the gaseous fluid freed of solvent; (2) in a second desorption stage recycling the gaseous regeneration fluid by means of a turbine (8) in a closed circuit, through the layers of solvent-impregnated active charcoal fibers (5), the said active charcoal fibers being heated by heating elements (6) placed below the layers of active charcoal fibers, said regeneration fluid being heated by a heater (14), the solvent adsorbed onto the active charcoal fibers being vaporized by heat and then being liquefied in a cryocondensation device cooled by a refrigeration unit (9),while any water vapor present in the regeneration fluid is separated off in the form of ice crystals; and (3) in a third purging stage, switching off the heating of resistors (6) and heater (14) and cooling the active charcoal (5) by purging with air or with the fresh neutral gas which follows the same path as during the desorption stage.