Two stage fluid catalytic cracking process and apparatus

An apparatus for two stage fluid catalytic cracking (FCC) of hydrocarbon feedstocks boiling above 200° C. for simultaneous maximization of light olefins such as ethylene and propylene and middle distillate range hydrocarbons with flexibility in operation for the maximization of gasoline with separate regenerators for regenerating different spent catalysts used therein comprising the following units:

• i) a first flow reactor having an inlet for injecting hydrocarbon feed and steam together, another inlet above the feed inlet for entry of regenerated catalyst at the beginning of the reactor, a gas solid separator-stripper at the other end of the reactor,
• ii) a gas solid separator preferably cyclone separators with stripper having multistage steam stripping means connected to the first flow reactor said unit (i), separator to separate spent catalyst from the reactor effluent vapors obtained from the first flow reactor and an outlet at the top of the stripper for exit of the hydrocarbon vapors and stripper to strip out the entrapped hydrocarbons from the spent catalyst, an outlet at the at the bottom of the stripper for exit of the spent catalyst,
• iii) a first fractionator connected to the top of the gas solid separator-stripper of unit (ii) for separating the reactor effluent vapors exiting therefrom into three product streams comprising, hydrocarbons boiling below 150° C., liquid hydrocarbons with boiling range 150-370° C. and unconverted bottoms (370° C.+);
• having means for collecting the fractionated products and outlets with transport means for transporting the hydrocarbons boiling below 150° C. to a second product separation section and unconverted bottoms as a feedstock to second flow reactor and liquid hydrocarbons with boiling range 150-370° C. is directly blended with the similar cuts obtained from second product separation section,
• iv) a second flow reactor having a first inlet for entry of C4 hydrocarbons/steam from second product separation section of said unit (iii) and a second inlet for entry of regenerated catalyst from the catalyst regenerator of the second stage, and a third inlet for naphtha range hydrocarbons from the second product separation section and a fourth inlet for entry of fresh feed and a fifth inlet for entry of unconverted hydrocarbons from first fractionator, and at the other end connected to a separation device with stripper for separating the spent catalyst and the cracked vapors therefrom,
• v) a separation device preferably cyclone separators with stripper having a multistage steam stripping means for separating the spent catalyst from the reactor effluent vapors coming out of the second flow reactor to the second product separation section for fractionating and separating out the desired hydrocarbon products,
• vi) a second product separation section comprising of a main fractionator and a gas concentration section, for fractionating the reactor effluent vapors from the second flow reactor of unit (iv) and hydrocarbons boiling below 150° C. from the first flow reactor, into different hydrocarbon products according to the desired cut ranges,
• vii) an upflow catalyst regenerator for regeneration of spent catalyst from the of first flow reactor having an inlet connected to the bottom of the stripper of said unit (ii) for entry of the spent catalyst therein near the bottom, entry of air/oxygen containing gas at the bottom and other elevations therein, and connected at the top with a cyclone containing vessel with closed couple cyclone separator system to remove the entrained regenerated catalyst particles from the flue gas and to collect the regenerated catalyst at the bottom of the vessel, and an outlet for exit of the flue gas therefrom, and
• viii) a dense or fast fluidized bed catalyst regenerator, for regenerating the spent catalyst collected from the separation device with stripper of unit (v).