Hydrocracking process and device with reduction of polynuclear aromatic compounds

A process for hydrocracking a feed, said feed comprising 20% to 100% by volume of compounds having a boiling temperature of more than 340° C., a sulphur content in the range 0.01% to 5% by weight, a nitrogen content of more than 500 ppm by weight, a cumulative nickel and vanadium content of less than 2 ppm by weight and an asphaltenes content of less than 3000 ppm by weight, said process consisting of:

• a) hydrocracking said feed, at a temperature of more than 200° C., a pressure of more than 1 MPa, a space velocity in the range 0.1 to 20 h−1 and a volume ratio, in litre of hydrogen/litre of feed, in the range 80 to 5000, obtaining a hydrocracked effluent,
• b) separating the effluent obtained from hydrocracking in a) carried out in a hot separation zone comprising a high pressure hot separator, said pressure being more than 0.5 MPa and less than the pressure employed in hydrocracking in a), and the temperature being in the range 200° C. to 450° C., and optionally a medium pressure hot separator at a pressure below 4.5 MPa and at a temperature in the range 200° C. to 450° C., obtaining a gaseous effluent from the head of the high pressure hot separator and a heavy effluent from the bottom of the high pressure hot separator,
• c) sending the gaseous effluent obtained from b) at the head of the high pressure hot separator directly to a cold separation zone comprising a high pressure cold separator at a temperature in the range 0° C. to 200° C., and at a pressure of more than 0.5 MPa and less than the pressure employed in b), and obtaining a gaseous effluent from the head of the high pressure cold separator and a heavy effluent from the bottom of the high pressure cold separator,
• d) separating the heavy effluent obtained from b), carried out in a separation column that is a stripper or a reboiler column, obtaining a gaseous effluent from the head of said column and a residue from the bottom of the column, and at least a portion of said residue, concentrated in HPNA, is eliminated by purge,
• e) fractionating the heavy effluent obtained from c) and of the gaseous effluent obtained in d) in a fractionation section, and obtaining at least one naphtha fraction, at least one gas oil fraction, and a residue and recycling said residue, in part or in its entirety, to hydrocracking in a).