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

A process for simultaneous conversion of lighter and heavier hydrocarbon feedstocks into improved yields of light olefins, liquid aromatics and other useful products by a continuous FCC operation in multiple reaction zones in different reactors operating under different regimes and conditions comprising the steps of:

• a) cracking the lighter hydrocarbon feedstock along with steam in the molar ratio of 1:60 to 60:1 in a bubbling or turbulent bed first reaction zone in the first reactor to get a first reactor effluent mixture;
• b) separating the first reactor effluent mixture of step (a) into a vapor rich phase and a solid rich phase;
• c) separating the vapor rich phase of step (b) in a product separator into C5− and C5+ fractions;
• d) recycling the C5+ fractions back to the first reaction zone and continuing the cracking operation until the aromatics concentration in C5+ fractions reaches more than 90 wt %;
• e) stripping a portion of the solid rich phase of step (b) containing coke laden catalyst using steam to remove entrapped hydrocarbons along with vapor rich phase entering the product separator:
• f) transferring the remaining portion of solid rich phase of step (b) containing coke laden catalyst of step (b) from the first reaction zone to a second reaction zone of a second reactor, cracking the heavier hydrocarbon feedstock therein at a relatively lesser temperature and pressure as compared with those in the first reaction zone to get a second reactor effluent mixture, wherein coke on the catalyst from the first reaction zone does not exceed 0.35 wt %;
• g) separating the effluent mixture of step (f) into a vapor rich phase and a solid rich phase containing coke laden spent catalyst;
• h) fractionating the vapor rich phase of step (g) to get different cracked products;
• i) stripping the solid rich phase of step (g) using steam to remove entrapped hydrocarbons along with vapor rich phase of step (g);
• and
• j) regenerating the coke laden stripped spent catalyst obtained from step (i) and step (e) in a common catalyst regenerator using air and/or an oxygen containing gas to produce an active regenerated catalyst for recirculating to the first reaction zone through regenerated catalyst standpipe and regenerated catalyst slide valve for the next cycle of operation.