Process for the preparation of olefins, involving de-asphalting, hydroconversion, hydrocracking and steam cracking

A process for producing olefins from a hydrocarbon feedstock (1) with a sulfur content of at least 0.1 weight %, an initial boiling point of at least 180° C. and a final boiling point of at least 600° C., said process comprising the following steps:

• a) a deasphalting step a) by extraction of said heavy hydrocarbon feedstock (1) using a solvent (2) or a mixture of solvents, enabling the production of an asphalt-comprising fraction (4) and of a deasphalted oil fraction (3),
• b) a step b) of hydroconversion performed in an ebullated-bed reactor, in which the asphalt fraction (4) is contacted, in the presence of hydrogen, with a hydroconversion catalyst, said step enabling the production of an effluent (5),
• c) a step c) of separation of the effluent (5) obtained from the hydroconversion step b) into a gaseous fraction (6), a fraction (7) comprising compounds with a boiling point of between 180 and 540° C., and a fraction (8) comprising compounds with a boiling point of less than 180° C.,
• d) a step d) of extraction of the aromatics from at least part of the deasphalted oil fraction (3) obtained from the deasphalting step a), and from at least part of the fraction (7) obtained from the separation step c), using a polar solvent (11), enabling the production of an extract fraction (9) and of a raffinate fraction (10),
• e) a step e) of fixed-bed hydrocracking of at least part of the extract fraction (9) obtained from the extraction step d) in the presence of hydrogen (12) and of a hydrocracking catalyst, enabling the production of an effluent (13),
• f) a step f) of separation of the effluent (13) obtained from the fixed-bed hydrocracking step e) into at least one gaseous fraction (15) and at least one liquid fraction (14) comprising compounds with a boiling point of less than or equal to 350° C.,
• g) a step g) of steam cracking of the raffinate fraction (10) obtained from the extraction step d), of the fraction (8) obtained from the separation step c) and of the liquid fraction (14) obtained from the separation step f), enabling the production of an effluent (16),
• h) a step h) of separation of the effluent (16) obtained from the steam cracking step g), enabling the production of at least one hydrogen-comprising fraction (17), of an ethylene-comprising fraction (18), of a propylene-comprising fraction (19) and of a fraction (20) comprising pyrolysis oil.