Patent ID: 8685232
Filing Date: 2014-04-01
Classification: C10G

Abstract:
1. A fluid catalytic cracking (FCC) process for manufacturing propylene and ethylene in increased yield, comprising cracking an olefinic naphtha stream and main hydrocarbon stock in combination with an olefinic C 4 hydrocarbon stream on a mixed FCC catalyst in an FCC unit having one or more risers, wherein each FCC riser comprises an acceleration zone at the lower portion thereof, a lift stream feed nozzle at the bottom of the acceleration zone, a main hydrocarbon stock feed nozzle above the acceleration zone and an olefinic naphtha feed nozzle at a location along the acceleration zone between the lift stream feed nozzle and main hydrocarbon stock feed nozzle, and wherein the catalyst comprises pentasil zeolite of 7 to 15 percent by weight and Y zeolite of 20 to 30 percent by weight and wherein the catalyst is injected at the bottom of each FCC riser, the olefinic naphtha is injected through the olefinic feed nozzle of each FCC riser, the main hydrocarbon stock is injected through the main hydrocarbon stock feed nozzle of each FCC riser and the lift stream is injected through the lift stream feed nozzle at the bottom of the acceleration zone of each riser, and wherein the lift stream comprises the olefinic C 4 hydrocarbon stream with or without steam and/or a fuel gas and wherein the olefinic C 4 hydrocarbon steam and olefinic naphtha stream and the main hydrocarbon stock are cracked in different zones of each FCC riser, the olefinic C 4 hydrocarbon stream and olefinic naphtha stream being cocracked in the acceleration zone of the riser and the main hydrocarbon stock being cracked above the acceleration zone at 600 to 800° C. and pressure of 0.8 to 5 kg/cm 2 (gauge) and weight hourly space velocity (WHSV) of 0.2 to 100 hr −1 and vapour residence time of 0.2 to 5 seconds.