The future of the refining industry will depend on supplying cheap, high driveability and clean fuels with the lowest CO2/km and operating with the best profitable manner. Our approach is to combine the present conversion process in the refineries, adapting the hardware available on site, and transform it in an economic way for hydrogen production with combined CO2 sequestration for Enhanced Oil Recovery (EOR).
This paper focuses on the Brazilian situation, discussing the steps required to transform the Fluid Catalytic Cracking process into clean fuels makers and CO2 generator for EOR. The FCC will be the route to process very heavy feedstock operating in partial or total combustion mode. For partial combustion mode, the first step is to transform the coke produced in these conversion units into CO stream; second step is to convert this CO stream into hydrogen by water gas-shift reactions. The partial or total combustion mode will be promoted with pure oxygen plus CO2 to obtain high CO2 concentration on the fuel gases. The advantage is that the flue gases are not diluted with nitrogen as when air is used for combustion, and therefore can be disposed of with minimal further downstream processing. Energy integration and process flexibility are key factors to achieve those goals. The present paper clarifies this vision of future and the R&D efforts devoted to achieve these challenges.
The Fluid Catalytic Cracking process (FCC) is presently the main conversion route in which the current refining scheme of Petroleo Brasileiro S.A. (PETROBRAS) is based (Fig.1). About 1.8 MM bpd of crude oil are processed in the distillation units generating approximately 0.52 MM bpd of vacuum gasoil which are converted in the FCC units into lighter products. Although the FCC capacity have been increasing, the quality of the processed feed is deteriorating, presenting lower API and high levels of contaminant metals (Ni and V) [1].
(Figure in full paper)
In terms of CO2 emissions, the FCC process is the second most important source in the refining scheme, process furnaces being the primary source as depicted in figure 2. In line with the corporate strategy of being an integrated energy company engaged with sustainable development, Petrobras has decided to study the feasibility of improving its operations and hardware to mitigate CO2 emissions. In parallel, studies are being performed in order to get carbon credits in the form of Clean Development Mechanism (CDM) projects as agreed in the Kyoto Protocol.
The present paper discusses alternatives to modify the FCC operation and hardware in order to produce a CO2-rich (>95% vol.) flue-gas stream from the FCC regenerator, which can be used in a different application and partially entrapped, reducing the global emission of this important greenhouse gas.
The most practical and economically attractive use for this CO2-rich stream is to inject it in depleted oil sources as an important agent for the enhanced oil recovery (EOR). In this way it is possible to considerably extend the lifetime of an oil field.
