modifications that can be required in FCC units to increase the co-processing of renewable feedstock are dedicated feed injection nozzles, bio-oil storage and feed lines, and equipment materials upgrading. Dedicated feed injection nozzles, specifically for injecting fast pyrolysis bio-oil into the FCC riser, ensure refiners can co-process bio-oils while minimising potential plugging or corrosion due to mixtures of fossil and renewable feeds that might result in blending issues. The latter is due to the presence of many oxygen-containing molecules that result in a polar phase immiscible with fossil feedstock. Bio-oil storage and feed lines should be built with mate- rial resistant to corrosion over long-duration exposure to bio-oils feeds. For renewable feedstock, organic acid (RCOOH, which is measured by total acid number [TAN]) and chlorides are the main impurities that could cause cor- rosion issues. The long-chain organic acids usually pres- ent in these feedstock are weak acids that slightly acidify free water in contact with the feedstock, such as in storage systems. Equipment materials upgrading of the reaction sec- tion and main fractionation overhead section should be evaluated due to corrosion risks associated with chloride- containing compounds. Against this backdrop, the Axens technological solutions provide support in co-processing matters, offering feedstock characterisation, pilot plant tests, catalyst evaluation, and corrosion and revamp stud- ies to deal with the co-processing challenges related to the incorporation of renewable feedstock in commercial units. A Mark Schmalfeld, Global Marketing Manager, mark. schmalfeld@basf.com, Hernando Salgado, Technical Service Manager IMEA, hernando.salgado@basf.com, and Alvin Chen, Ph.D., Global Technology Application Manager, alvin.u.chen@basf.com , BASF Refinery Catalysts To increase the coprocessing of renewable feedstocks in FCC units and hydrotreaters, specific modifications are necessary to enhance compatibility, efficiency, and yield. Each modification must be tailored to the type of alter- native feedstock being processed, such as vegetable oils, animal fats, or other bio-based materials. The following discussion focuses on suggested modifications, their rel- evance to various feedstocks, and recommended pretreat- ment changes. FCC modifications Catalyst selection Modification: Use catalysts specifically designed for renew- able feedstocks, such as those that are more effective in cracking triglycerides found in vegetable oils. Relevance: Different feedstocks have varying molecular structures. For instance, vegetable oils require catalysts that promote the cracking of larger hydrocarbon chains into lighter fractions. Reactor design enhancements Modification: Implement dual riser reactors or modify exist- ing risers to allow for better mixing and residence time for alternative feeds.
Relevance: Lighter renewable feedstocks may require different flow dynamics compared to heavier petroleum feedstocks. Feed injection Modification: Install dedicated feed nozzles for renewable feedstocks. Relevance: Renewable feedstocks may not be stable at typical FCC feed conditions and may have to be handled differently (thermal stability, fouling, solution compatibility) to ensure reliable operation. Operating conditions adjustment Modification: Adjust temperature and pressure settings to optimise the processing of renewable feeds. Relevance: Each type of feedstock may have an optimal temperature and pressure range for effective cracking. For example, animal fats typically require slightly different con- ditions than vegetable oils. Relevance: Processing high concentrations of renewables (particularly bio-derived oils) can produce significant water, CO, and CO₂ yields in the riser. Hydrotreater modifications Hydrogen supply and management Downstream hardware modifications Modification: Increase sour water handling capacity. Modification: Upgrade hydrogen supply systems to ensure consistent and adequate hydrogen availability for the hydroprocessing of renewable feeds. Relevance: Many renewable feedstocks have higher oxy- gen content and thus require more hydrogen for effective hydrotreatment. Catalyst adaptation Modification: Utilise catalysts that are optimised for renew- able feedstocks, particularly those that can effectively remove oxygen and sulphur. Relevance: Different feeds, like palm oil vs used cooking oil, may require unique catalyst properties to achieve desired saturation and hydrodesulphurisation outcomes. Reactor configuration Modification: Modify existing reactors to accommodate higher flow rates and pressures, which can enhance the processing of lighter biofeedstocks. Relevance: Different feedstocks can have varying viscosi- ties; heavier oils might necessitate different reactor designs compared to lighter, more fluid alternatives. Pretreatment modifications De-oxygenation Modification: Implement de-oxygenation processes such as hydrotreatment or thermal treatment before feeding into the FCC, hydrotreater, or downstream equipment. Relevance: Reducing oxygen content can enhance yield and performance by minimising the formation of undesir- able byproducts during processing.
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PTQ Q1 2025
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