Cracking hydrocarbon feedstock containing resid utilizing partial condensation of vapor phase from vapor/liquid separation to mitigate fouling in a flash/separation vessel

A process for cracking a hydrocarbon feedstock containing resid, said process comprising:

• (a) heating said hydrocarbon feedstock;
• (b) mixing the heated hydrocarbon feedstock with steam to form a mixture stream;
• (c) introducing the mixture stream in a flash/separation vessel through an inlet to form i) a vapor phase at its dew point which contains a lesser portion of coke precursors, and ii) a liquid phase which contains a greater portion of coke precursors;
• (d) partially condensing said vapor phase within said flash/separation vessel by contacting said vapor phase with a condenser, which condenses at least some of said lesser portion of coke precursors, which adds to said liquid phase, said condensing providing a vapor phase above the condenser of reduced coke precursors content;
• (e) removing the vapor phase of reduced coke precursors content as overhead through an overhead outlet, and said liquid phase as bottoms, from said flash/separation vessel;
• (f) heating the vapor phase;
• (g) cracking the heated vapor phase in a radiant section of a pyrolysis furnace to produce an effluent comprising olefins, said pyrolysis furnace comprising a radiant section and a convection section;
• and
• (h) quenching the effluent and recovering cracked product therefrom.