Oxy-combustion Technology Development for Fluid Catalytic Crackers (FCC) – Large Pilot Scale Demonstration

Abstract

The Fluid Catalytic Cracking (FCC) process may represent as much as 30% of the total CO2 emissions from a refinery. Oxy-combustion technology is a promising option to reduce these emissions and as part of the CO2 Capture Project-Phase 3 (CCP3), Petrobras has retrofitted its large pilot scale FCC unit to demonstrate the technical viability of operating the unit in oxy-combustion conditions. The startup of the unit has shown that the transition from air to oxy is fast, however there must be a close monitoring of the excess O2 in the flue gas as it may reach low levels, taking the unit to a partial burn mode. Two extreme conditions were tested and these were called the same heat balance condition and secondly the same flow rate condition. For the same heat balance, the O2 content in the recycled gas mixture is higher and there is minimum impact on unit operational conditions and product yields. For the same flow rate, a higher overall feed conversion is observed due to a larger catalyst circulation. The oxy-combustion operation in this last condition allowed an increase of feed processing with very low changes in product slate. In all oxy tests, the CO2 content in the flue gas showed values close to 95%vol. Overall, the tests have demonstrated that it is technically viable to operate an FCC unit in the oxy-combustion mode.