Process for simultaneous cracking of lighter and heavier hydrocarbon feed and system for the same

Abstract

The invention provides for a process and apparatus for simultaneous conversion of lighter and heavier hydrocarbon feedstocks into improved yields of light olefins in the range of C2 to C4, liquid aromatics in the range C6 to C8 mainly benzene, toluene, xylene and ethyl benzene and other useful products employing at least two different reactors operated in series with respect to catalyst flow and parallel with respect to feed flow under different regimes and process conditions with same catalyst system.

1 . A FCC catalyst system for simultaneous cracking of lighter and heavier hydrocarbon feedstocks in multiple reactors to produce improved yields of light olefins and liquid aromatics and the like, comprising Y-zeolite in rare earth ultra-stabilized form with bottom cracking components consisting of peptized alumina, acidic silica alumina or gamma alumina, pentasil shape selective zeolites or a mixture thereof as the active components. 
     
     
         2 . The catalyst system as claimed in  claim 1 , wherein the catalyst comprises of solid micro-spherical acidic materials with average particle size of 60-80 microns and apparent bulk density of 0.7 to 1.0 gm/cc. 
     
     
         3 . The catalyst system as claimed in  claim 1 , wherein the active catalyst components are supported on relatively inactive materials such as silica/alumina or silica-alumina compounds, including kaolinites or with active matrix components like pseudobomite alumina. 
     
     
         4 . A process for preparing a catalyst system for simultaneous cracking of lighter and heavier hydrocarbon feedstocks in multiple reactors to produce improved yields of light olefins and liquid aromatics and the like, wherein Y-zeolite in rare earth ultra-stabilized form and a bottom cracking component selected from peptized alumina, acidic silica alumina or gamma alumina, pentasil shape selective zeolites or a mixture thereof are mixed together or separately bound, supported on relatively inactive materials and spray-dried to get micro-spheres, washed, rare earth exchanged and flash dried to produce the finished catalyst system. 
     
     
         5 . The process as claimed in  claim 4 , wherein the active catalyst components as finished micro-spheres in separate particles are physically blended in the desired composition. 
     
     
         6 . A multi-reactor fluidized bed catalytic cracking apparatus for the production of light olefins and liquid aromatics and the like, through simultaneous cracking of lighter and heavier hydrocarbon feedstocks in separate reaction zones comprising at least a first reaction zone in a first reactor, a second reaction zone in a second reactor and a catalyst regenerator. 
     
     
         7 . The apparatus as claimed in  claim 6 , wherein the first reactor being connected at the bottom with a distributor inlet for entry of preheated lighter hydrocarbon feed/recycled feed along with process steam via a conduit, has an inlet for entry of hot regenerated catalyst through a distributor via a slide valve from the catalyst regenerator, a separation device for separation of coke laden catalyst from the cracked products, a stripper means for stripping coked catalyst from the cracked product vapor, an outlet for the product vapor to reach to a main fractionator via a plenum chamber; an outlet at the bottom for circulation of partially coked catalyst to the bottom of the second reactor through a slide valve; an outlet for removing coke laden spent catalyst to the regenerator; the second reactor, preferably a riser, having an inlet for hot fresh heavy feedstock with dispersion steam near the bottom through a single or multiple feed nozzle, an inlet each for recycle feed and dilution steam near the bottom at different elevations of the riser and at the bottom for the regenerated catalyst through slide valve stated above and for the lift/stabilization steam; a termination device with separator for the separation of spent catalyst and product vapor mixture, a stripper means for stripping coke laden catalyst from the cracked hydrocarbons, an outlet for the spent catalyst to the regenerator, an outlet for the product vapor to the main fractionator via a plenum chamber; the catalyst regenerator has an inlet for the source of coke laden spent catalyst distributed through a distributor, an inlet at the bottom for the source of air or an oxygen containing gas, an outlet for the regenerated catalyst linked to the first reactor, a separation device for separating flue gas from the regenerated catalyst, an outlet for the flue gas and an outlet for the regenerated catalyst linked to the first reactor. 
     
     
         8 . The apparatus as claimed in  claim 6 , wherein the catalyst regenerator is a single stage or multistage regenerator. 
     
     
         9 . The apparatus as claimed in  claim 6 , wherein the distributor is selected from manifold type, concentric ring type, perforated plate type and the like.