Processes and systems for steam cracking hydrocarbon feeds

A system for steam cracking hydrocarbons, comprising:

• a steam cracker comprising a convection section and a radiant section, wherein:
• a first convection line is disposed within the convection section and configured to flow a hydrocarbon feed therethrough to produce a preheated hydrocarbon feed,
• a mixing device is in fluid communication with the first convection line and configured to receive the preheated hydrocarbon feed and a liquid water feed produce a mixture,
• a second convection line is disposed within the convection section and configured to receive and flow the mixture therethrough to produce a heated mixture, and
• a radiant line is disposed within the radiant section and configured to receive and flow at least a portion of the heated mixture therethrough to produce a steam cracker effluent;
• a first separation stage configured to separate a process gas comprising molecular hydrogen and C1-C4 hydrocarbons, a steam cracker naphtha, a condensed process water, and one or more heavy steam cracker products from the steam cracker effluent, wherein the condensed process water comprises entrained hydrocarbons;
• a second separation stage configured to separate at least a portion of the entrained hydrocarbons from the condensed process water to produce a purified process water;
• a dilution steam generator configured to heat at least a portion of the purified process water to produce dilution steam;
• and
• at least one of:
• a first recycle line configured to convey a portion of the condensed process water from the first separation stage to the mixing device to provide at least a portion of the liquid water received by the mixing device;
• a second recycle line configured to convey a portion of the purified process water from the second separation stage to the mixing device to provide at least a portion of the liquid water received by the mixing device;
• and
• a third recycle line configured to convey a condensed dilution steam from an optional dilution steam condenser to the mixing device to provide at least a portion of the liquid water received by the mixing device.

A process for steam cracking hydrocarbons, comprising:

• heating a hydrocarbon feed to produce a preheated hydrocarbon feed;
• combining liquid water with the preheated hydrocarbon feed to produce a mixture;
• heating the mixture within a convection section of a steam cracker furnace to produce a heated mixture;
• steam cracking at least a portion of the heated mixture within a radiant section of the steam cracker furnace to produce a steam cracker effluent;
• separating a process gas comprising molecular hydrogen and C1-C4 hydrocarbons, a steam cracker naphtha, a condensed process water, and one or more heavy steam cracker products from the steam cracker effluent, wherein the condensed process water comprises entrained hydrocarbons;
• separating at least a portion of the entrained hydrocarbons from the condensed process water to produce a purified process water;
• and
• heating at least a portion of the purified process water to produce dilution steam,
• wherein the liquid water combined with the preheated hydrocarbon feed comprises at least a portion of the purified process water.