This is a multiple effects with recycling and use of a draw-off plate for the selective extraction by solvent of the hydrocarbon mixtures

摘要

Selective multiple-effect extraction process, with recycling, for mixtures of hydrocarbons (introduced via the conduit 4) using a solvent (introduced via the conduit 5) circulating countercurrentwise, comprising a main column 1 divided in two by a draw-off tray 3 and a refractionation column 2, in which columns the same solvent circulates, making it possible to separate the said mixture of hydrocarbons into raffinate (leaving via the conduit 10), pseudoraffinate (leaving via the conduit 14) and extract (leaving via the conduit 25), the solvent containing fresh extract and leaving the refractionation column 2 is, before being recycled into the main column 1, first freed from a large part of the extract by salting out at a lower temperature (in the separator 12) and then reheated (in the reheater 16). The process makes it possible to increase the quantity of solvent employed for the extraction, by recycling into the main column below and above the draw-off tray, the solvent employed, freed from most of the extract by salting out. IMAGE