Oxy-firing has been confirmed by CCP as a viable technology from a technical and economic standpoint for capturing CO2 from the main emitting component of refinery operations, the Fluid Catalytic Cracking (FCC) unit. This comes as a result of the completion of CCP’s first capture field demonstration, which took place at a Petrobras research facility in Paraná state, Brazil.
The successful test has brought closer a more cost-effective technology capable of capturing up to 95% of FCC CO2 emissions, potentially equating to some 20-30% of emissions from a typical refinery. The project tested start-up and shut-down procedures and different operational conditions and process configurations – allowing the CCP partners to gain reliable data for scale-up.
The refinery is a challenging environment for capturing CO2, with many different operations producing emissions, said the CCP. The FCC unit converts heavy, lower-value hydrocarbon feedstock into lighter, more valuable products and is often the largest single source of CO2 emissions. Traditionally, air is used to regenerate the catalyst, by burning the coke deposited on the surface. In the oxy-combustion mode, air is replaced by pure oxygen, which is diluted with recycled CO2 to maintain thermal balance and catalyst fluidization.
Nigel Jenvey, CCP Chairman said: “This is a significant moment for CCP and the advancement of CCS. Our first demonstration project has successfully met its objectives and proved that oxy-firing is a viable way of reducing CO2 emissions from oil refineries. This project has shown the real value of collaboration by those within the oil and gas industry in order to discover insights and develop technologies that can help cut our own emissions footprint.”
The main results from the demonstration are:
-
Technical viability was proved with different feed qualities (VGO, ATR) and in two extreme operating conditions (Same Heat Balance, Same Inert Volumetric Flow Rate), with the same or higher product yields
-
The purity of captured CO2 reached the target 93-95% under oxy-firing conditions
-
Smooth and fast switch between air and oxy-firing through effective monitoring of excess CO2 in the flue gas
-
A significant gain in operational flexibility was achieved, meaning the cost of CO2 capture can be somewhat mitigated. This flexibility allows either higher carbon throughput (10% higher flowrate with same conversion) or the processing of lower cost heavier feedstock with the same results
-
Catalyst entrainment rates compared to combustion in air varied from lower (Same Heat Balance) to higher (Same Inert Volumetric Flow Rate). An interim condition – Same Solid Entrainment – was also tested delivering the same entrainment as in air operation
-
Increase in oxygen partial pressure did not lead to increased catalyst deactivation, thus indicating there will be no need to increase catalyst make-up in full-scale operating conditions. However greater catalyst replacement rate may be needed where higher entrainment rates lead to higher cyclone loading and catalyst loss (most notably when the CO2 recycling rate is above that of the Same Solid Entrainment condition)
-
Potential corrosion issues were identified early in the testing due to the presence of NOx and SOx impurities in the flue gas. These are fully understood and are manageable through proper design.