Process for extracting aromatic hydrocarbons from hydrocarbon mixtures containing same

Claim 1

A PROCESS FOR OBTAINING AROMATIC HYDROCARBONS FROM MIXTURES OF AROMATIC HYDROCARBOINS AND NON-AROMATIC HYDROCARBONS BY EXTRACTION WITH A SOLVENT, CHARACTERIZED IN THAT IT COMPRISES THE STEPS OF: INTRODUCING THE HYDROCARBONACEOUS MIXTURE IN AN INTERMEDIATE POINT OF A COUNTERFLOW EXTRACTION SYSTEM AND INTRODUCING AT ONE END OF SAID EXTRACTION SYSTEM A SOLVENT ESSENTIALLY CONSISTING OF FORMYLMORPHOLINE AND, FROM THE OPPOSITE END, A REFLUXING AGENT ESSENTIALLY CONSISTING OF A LIGHT PARAFFIN FRACTION HAVING A BOILING POINT SUBSTANTIALLY LOWER THAN THAT OF THE HYDROCARBONS CONTAINED IN THE HYDROCARBONACEOUS MIXTURE, WHILE MAINTAINING THE PHASES IN MUTUAL CONTACT AT A TEMPERATURE BETWEEN 20*C. AND 90*C., DISCHARGING A REFINED STOCK SUBSTANTIALLY DEVOID OF AROMATIC HYDROCARBONS AND OF SOLVENT FROM THE SAME END OF THE SYSTEM WHEREIN THE SOLVENT IS INTRODUCED, DISCHARGING AN EXTRACT FORMED BY THE SOLVENT, THE AROMATIC HYDROCARBONS AND A PORTION OF THE REFLUXING AGENT AND SUBSTANTIALLY FREE AND A PORTION OF THE REFLUXING AGENT AND SUBSTANTIALLY FREE OF THE NON-AROMATIC HYDROCARBONS FED-IN WITH THE HYDROCARBONACEOUS MIXTURE, SUBJECTING THE EXTRACT THUS OBTAINED TO WASHING WITHIN A COUNTERFLOW CONTACT SYSTEM WITH A LIGHT PARAFFIN FRACTION HAVING A BOILING POINT DEFINITELY LOWER THAN THAT OF THE AROMATIC HYDROCARBONS PRESENT IN THE EXTRACT, DISCHARGING FROM THE CONTACT SYSTEM IN WHICH THE WASHING IS CARRIED OUT A HEAVIER PHASE CONSISTING OF ALL THE SOLVENT AND SUBSTANTIALLY FREE OF HYDROCARBONS, AND DISCHARGING FROM THE OPPOSITE END OF A HYDROCARBONACEOUS PHASE CONSISTING OF THE SOLVENT-FREED AROMATIC HYDROCARBONS EXTRACTED FROM THE HYDROCARBONACEOUS MIXTURE AND LIGHT PARAFFIN HYDROCARBONS HAVING A BOILING POINT SUBSTANTIALLY LOWER THAN THAT OF THE MORE VOLATILE AROMATIC HYDROCARBON PRESENT IN THE SYSTEM, SEPARATING THE EXTRACTED AROMATIC HYDROCARBONS AND LIGHT PARAFFIN HYDROCARBONS HAVING A BOILING POINT SUBSTANTIALLY LOWER THAN THAT OF THE MORE VOLATILE AROMATIC HYDROCARBON PRESENT IN THE SYSTEM FROM THE SOLVENT-FREED EXTRACT BY EVAPORATION UNDER SUCH CONDITIONS AS TO EVOLVE THEREFROM A MAJOR ALIQUOT OF THE LOWBOILING LIGHT PARAFFIN FRACTION WHICH IS UTILIZED AS A REFLUXING AGENT AGAIN AND AS A WASHING AGENT, SEPARATING THEREAFTER FROM THE RESIDUAL EXTRACT THE REMAINDER OF THE LIGHT PARAFFIN FRACTION ALONG WITH A PORTION OF THE MORE VOLATILE AROMATIC HYDROCARBON AS A STREAM, MIXING SAID STREAM OBTAINED WITH THE FEED TO THE EXTRACTION SYSTEM AND NOT AS A REFLUX, AND OBTAINING AS A BOTTOM PRODUCT A HYDROCARBONACEOUS FRACTION CONSISTING OF SUBSTANTIALLY PURE AROMATIC HYDROCARBONS THE TEMPERATURE BEING MAINTAINED BETWEEN 20*C. AND 90*C. THROUGHOUT THE WHOLE PROCESS.