Method and system for producing olefins by steam cracking of a heavier hydrocarbon

A system for producing olefins by the steam cracking of a heavier hydrocarbon, comprising:

• a first vapour-liquid separator (8) configured to perform a first separation (such as flash) of the heavier hydrocarbon, to obtain a first vapour stream and a first liquid stream,
• a separator, such as a separation column (7), configured to partially condense (e.g. by fractional distillation, referred to as a second separation) the first vapour stream to obtain a condensate (referred to as a third heavier fraction, preferably having an initial boiling temperature of 165° C. or higher, more preferably having a distillation range of 180-380° C.),
• a introduction means configured to introduce at least a portion (such as 50 wt % or higher or 80 wt % or higher of its total weight) of the third heavier fraction into the first liquid stream to obtain a first modified liquid stream,
• a second vapour-liquid separator (9) configured to perform a third separation (such as flash) of the first modified liquid stream to obtain a second vapour stream and a second liquid stream, a steam cracker configured to steam-crack the second vapour stream to obtain a cracked gas effluent comprising olefins.