Dual riser catalytic cracker for increased light olefin yield

A process for improving the yield of ethylene and propylene from a light naphtha feedstock, comprising:

• obtaining light naphtha feedstock from a primary cracking zone comprising a cracking catalyst;
• contacting the light naphtha feedstock with an olefin catalyst in an olefin producing zone to produce an ethylene- and propylene-rich stream;
• separating the olefin catalyst from the ethylene- and propylene-rich stream in a separator zone;
• regenerating at least a portion of the olefin catalyst by combusting coke deposited on a surface of the olefin catalyst in an oxygen-containing environment;
• directly heating at least a portion of the olefin catalyst with a stream of hot combustion gas;
• and
• returning the olefin catalyst to the olefin producing zone.

An apparatus for processing light naphtha from a catalytic cracking zone to produce ethylene and propylene, the apparatus comprising:

• a catalytic cracking zone comprising a cracking catalyst;
• a first separator zone at the exit of the catalytic cracking zone for separation of the catalytic cracking zone effluent from the cracking catalyst;
• a regenerator for the cracking catalyst, wherein coke deposited on the cracking catalyst is removed by combustion, the regenerator for the cracking catalyst in fluid communication with the first separator zone, and the regenerator for the cracking catalyst in communication with the entrance of the catalytic cracking zone;
• an olefin cracking zone comprising an olefin catalyst;
• a second separator at the exit of the olefin cracking zone for separation of the olefin cracking zone effluent from the olefin catalyst;
• a regenerator for the olefin catalyst, wherein coke deposited on the olefin catalyst is removed by combustion, the regenerator for the olefin catalyst in fluid communication with the second separator zone, and the regenerator for the olefin catalyst in fluid communication with the entrance of the olefin cracking zone;
• and
• a heater in fluid communication with a source of hot combustion gases to heat at least a portion of the olefin catalyst prior to addition to the olefin cracking zone.