Processes and systems for co-processing a hydrocarbon feed and a heavy feed containing a plastic material

A process for converting hydrocarbons by pyrolysis, comprising:

• heating a hydrocarbon feed within a convection section of a steam cracking furnace and combining the hydrocarbon feed with an aqueous fluid to produce a heated mixture comprising hydrocarbons and steam, wherein the heating is carried out before, during, and/or after the hydrocarbon feed is combined with the aqueous fluid, and wherein the heated mixture is a two-phase gas/liquid mixture;
• introducing the heated mixture and a heavy feed comprising a plastic material into a vessel;
• cracking a portion of the plastic material within the vessel under plastic pyrolysis conditions;
• obtaining a liquid phase effluent and a vapor phase effluent exiting the vessel;
• heating at least a portion of the liquid phase effluent to produce a heated fluid stream;
• recycling at least a portion of the heated fluid stream to the vessel;
• heating the vapor phase effluent within the convection section of the steam cracking furnace to produce a heated vapor phase effluent;
• and
• steam cracking the heated vapor phase effluent within a radiant section of the steam cracking furnace to produce a steam cracker effluent comprising olefins.