Process for converting whole crude to ethylene

A process for converting whole crudes and other heavy hydrocarbon streams to produce ethylene, the process comprising:

• separating a whole crude into at least a light boiling fraction, a medium boiling fraction, and a high boiling residue fraction;
• processing the medium boiling fraction, the high boiling fraction, or both, in one or more hydroprocessing steps to produce a hydroprocessed medium boiling fraction, a hydroprocessed residue fraction, or both;
• feeding the hydroprocessed medium boiling fraction, hydroprocessed residue fraction, or both, and the light boiling fraction to a steam cracker;
• recovering a light fraction comprising C1-C4 hydrocarbons and a pyrolysis oil;
• feeding the light fraction to a first separator and recovering a C1-C3 stream and a mixed C4 and C4+ stream, comprising isoolefins, olefins, and dienes;
• feeding the mixed C4 and C4+ stream, comprising isoolefins, olefins, and dienes to a second separator and recovering a mixed C4 stream comprising isoolefins, olefins, and a C4+ stream;
• dimerizing the mixed C4 stream in a dimerization unit to produce a dimerized product stream;
• hydrogenating the dimerized product stream in a total hydrogenation system, producing a hydrogenated dimer product stream;
• and
• cracking the hydrogenated dimer product stream in a thermal cracking reactor system comprising one or more thermal cracking reactors, producing one or more of hydrogen, methane, ethylene, propylene, n-butenes, and isobutene.