Patent ID: 8173854

Claim:
A process for cracking an undesalted hydrocarbon feedstock containing salt and particulate matter, said process performed in sequence comprising: a. heating said undesalted hydrocarbon feedstock containing salt and particulate matter to provide a heated hydrocarbon feedstock containing salt and particulate matter to a temperature between about 100° C. and about 340° C. in a first convection section tube bank of a pyrolysis furnace; b. partially desalting by a centrifugal separator said heated hydrocarbon feedstock containing salt and particulate matter to an extent sufficient to avoid accumulation of salt and particulate matter in said liquid phase at levels which interfere with the subsequent intended use of said liquid phase; and further wherein said centrifugal separator is a cyclone separator consisting essentially of a tangential inlet, an upper outlet for removing a partially desalted hydrocarbon stream and a lower outlet for removing bottoms containing water, salt, and/or particulate matter, bottoms and wherein said partially desalted hydrocarbon feedstock contains particulate matter, non-volatiles and about 0.01 wt % to about 0.8 wt % salt; c. adding to said partially desalted hydrocarbon feedstock (i) steam and optionally water and (ii) a heavy hydrocarbon having a T 50 boiling point greater than that of the partially desalted hydrocarbon feedstock to produce a hydrocarbon blend having a T 98 boiling point that is at least about 28° C. greater than that of the undesalted hydrocarbon feedstock, the heavy hydrocarbon being about 10.0 wt % to about 50.0 wt % of the weight of the hydrocarbon blend; d. feeding the hydrocarbon blend to a flash/separation vessel, about 5 wt %, to about 30 wt % of the hydrocarbon blend being liquid at the flash/separation vessel's inlet; e. separating the hydrocarbon blend into a vapor phase and a liquid phase in the flash/separation vessel, wherein vapor liquid split is controlled by i) varying the amount of added steam and/or water added to the partially desalted hydrocarbon feedstock, and/or ii) the amount of heavy hydrocarbon fluid combined with the partially desalted hydrocarbon feedstock, such that the vapor phase is less than 98% by weight of the hydrocarbon blend, said liquid phase comprising a sufficient portion of the hydrocarbon blend to maintain salt and particulate matter in suspension; f. removing the vapor phase from the flash/separation vessel; and g. cracking the vapor phase to produce an effluent comprising olefins.