Hydrocracking process

A plant for hydrocracking a petroleum feedstock comprising at least 10% by volume of compounds that boil above 340° C., said plant successively comprising:

• (a) at least one section (2) for hydrocracking the feedstock (1) in order to obtain a hydrocracked effluent,
• (b) at least one section (4) for liquid/gas separation of the hydrocracked effluent in order to obtain a gaseous effluent (5) and a liquid effluent (9),
• (c) a section for fractionating said liquid effluent, comprising at least one column (12), at a pressure P1 at the bottom of the column, to produce at least a first distillate (13, 14) and a first residue (15),
• (d) a line for recycling a first portion (18) of said first residue (15) to one of the at least one hydrocracking section (2),
• (e) a section for rectifying a second portion (20) of the first residue (15) obtained in the fractionating zone, comprising at least one column (21), at a pressure P2 at the top thereof which is at least 0.05 MPa lower than the pressure P1, to obtain at least a secondary distillate (23), a secondary residue (16) and a vapor stream (22),
• (f) a section for purging at least one portion, or all, of the secondary residue (16), and
• (g) a line for recycling all or part of said secondary distillate (23) to the hydrocracking section (2) or at least one of the hydrocracking sections, after an optional gas separation section,
• wherein said plant is free of a line for recycling all or part of the of the overhead vapor stream (22) resulting from the rectifying step (e).