Patent ID: 7138047

Claim:
A process for cracking a heavy hydrocarbon feedstock in a furnace having at least a convection section and a radiant section; said process comprising: (a) heating said heavy hydrocarbon feedstock in said convection section to form a heated feedstock; (b) introducing a fluid and steam to said heated feedstock to form a mixture; (c) heating said mixture in said convection section to form a heated mixture; said heated mixture having a vapor phase and a liquid phase; (d) substantially separating said vapor phase and said liquid phase; (e) feeding the separated vapor phase to said radiant section to crack at least a portion of hydrocarbons in said separated vapor phase; (f) varying the rate of introduction of said fluid and the rate of introduction of said steam in response to changes in at least one operating parameter of said process to maintain the ratio of said separated vapor phase to the separated liquid phase substantially constant.