PROCESS FOR CRACKING TO LIGHT OLEFINS

A process for catalytic production of olefins comprises contacting a first hydrocarbon stream and a first stream of fluid catalyst in a first riser to produce a first cracked product stream and a spent catalyst stream. The first cracked product stream is separated in a main column. An overhead stream from the main column is separated into a second hydrocarbon stream. The second hydrocarbon stream is contacted with a second stream of fluid catalyst in a second riser to produce a second cracked product stream and a first stream of cool catalyst. A third hydrocarbon stream is obtained from the overhead stream and/or from the second cracked product stream. The third hydrocarbon stream is contacted with a third stream of fluid catalyst in a third riser to produce a third cracked product stream and a second stream of cool catalyst.