Patent ID: 7427381

Claim:
An apparatus for cracking a hydrocarbon feedstock containing resid, comprising: (a) a heating zone for heating said hydrocarbon feedstock to provide heated hydrocarbon feedstock; (b) a mixing zone for mixing a primary dilution steam stream with said heated hydrocarbon feedstock to provide a heated two-phase stratified open channel flow mixture stream; (c) a vapor/liquid separation zone for treating vapor/liquid mixtures of hydrocarbons and steam, said separation zone comprising: (i) a substantially cylindrical vertical drum having an upper cap section, a middle section comprising a circular wall, and a lower cap section; (ii) an overhead vapor outlet attached to said upper cap section; (iii) at least one substantially tangentially positioned inlet in the wall of said middle section for introducing said flow along said wall; (iv) an annular structure located in the middle section, comprising A) an annular ceiling section extending from the circular wall and B) an internal vertical side wall to which said ceiling section extends, said side wall being positioned substantially concentrically to, but away from, said circular wall, said annular structure blocking the upward passage of said vapor/liquid mixtures along the circular wall beyond said ceiling section, and said annular structure circumscribing an open core having sufficient cross-sectional area to permit vapor velocity low enough to avoid significant entrainment of liquid; and (v) a substantially concentrically positioned, substantially cylindrical boot of less diameter than said middle section, said boot communicating with said lower cap section, and further comprising an inlet for quench oil and a liquid outlet at its lower end; (d) a pyrolysis furnace comprising a convection section, and a radiant section for cracking the vapor phase from the overhead vapor outlet to produce an effluent comprising olefins; (e) a means for quenching the effluent; and (f) a recovery train for recovering cracked product from the quenched effluent.