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  • How can the FCC unit be upgraded to benefit petrochemical integration?

    Feb-2025

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  • Mark Schmalfeld, BASF Refinery Catalysts, mark.schmalfeld@basf.com

    Upgrading the FCC unit can significantly enhance the integration of petrochemical processes within refineries. The unit primarily converts heavy petroleum feedstocks into lighter, more valuable products like gasoline and diesel. However, by implementing specific upgrades, refineries can optimise the FCC unit to produce higher yields of petrochemical feedstocks, thus improving overall operational efficiency and profitability.

    Choosing advanced catalysts that are more selective towards lighter olefins, such as propylene and ethylene, can significantly increase the output of petrochemical precursors. Some modern catalysts also have enhanced stability and longer lifetimes, reducing the frequency of catalyst replacement and downtime.

    Modifying the FCC unit’s riser section allows for better catalyst distribution and contact time with the feedstock. A design that promotes turbulent flow can enhance catalyst effectiveness by improving the distribution of catalyst within the unit. Special bed riser terminations can also increase residence time to increase reaction severity. The implementation of a secondary or dedicated riser to crack recycled light naphtha also can play a fundamental role in maximising light olefins yield, especially in the range of ethylene and propylene under severe reaction conditions. Additionally, upgrading to advanced catalyst injection systems ensures uniform dispersion and optimal contact between feed and catalyst. Upgrades to injection systems can also be beneficial when using new advanced catalysts.

    Adjusting operating conditions such as temperature, pressure, and feedstock composition can help in maximising desired olefins production. Increasing the severity of the cracking process can lead to higher yields of lighter products but requires careful balancing to avoid excessive coke formation and catalyst deactivation. High-temperature equipment such as reactors and advanced separators may need to be changed to handle the desired operational conditions. One particular feature that allows high light olefins yield is the reduction of the hydrocarbons partial pressure by increasing steam streams to the reaction environment. This facilitates the equilibrium conditions to increase the conversion of heavy hydrocarbons to light olefin molecules. In this regard, some units maximising light olefins operate within the range of 10-20% steam-to-feed ratio.

    Installing high-temperature reactors or modifying existing reactors to handle elevated temperatures safely can improve the cracking of heavier feedstocks. Utilising high-efficiency separators can better recover lighter products, minimising the loss of valuable olefins.
    Petrochemical integration

    Refineries can install downstream units such as olefin conversion units (OCUs), fractionators or propane dehydrogenation (PDH) units that utilise the lighter products generated from the FCC. Another interesting integration is with steam cracking units (SCU) since ethylene produced by FCC can be recovered, while ethane can be further converted to ethylene in the SCU. Modifications to piping and the addition of heat exchangers may also be necessary to connect these units effectively to the existing FCC unit. This integration allows for a more seamless transition from refining to petrochemical production, effectively creating a more versatile and adaptable processing facility.

    Coprocessing biofeedstocks or lighter hydrocarbons alongside conventional feeds in the FCC unit can diversify the product slate. This method not only helps in meeting regulatory requirements for renewable content but also allows for the production of unique petrochemical intermediates. Alternative feeds often require dedicated storage systems. Additional equipment modifications could include enhancing feedstock pretreatment systems to accommodate biofeedstocks or lighter hydrocarbons. This might involve upgrading pumps and heat exchangers to handle different viscosities and properties of the new feedstocks. Additionally, FCC licensors have unique equipment modifications they can recommend for co-processing, particularly around how the alternative feedstocks are injected into the FCC.

    Implementing advanced process control systems can optimise the FCC unit’s performance in real-time. These systems can adjust parameters dynamically based on feedstock variations and desired product specifications, maximising yield and minimising waste. Many advance control systems are already available today in most refiners, such as real-time monitoring tools and automated control systems. This includes the installation of advanced sensors for temperature, pressure, and composition analysis to enable real-time adjustments and optimisation of the cracking process.

    Upgrades
    Advanced distributed control systems (DCS) upgrades can dynamically adjust operational parameters based on feedstock characteristics and desired product yields, while upgrading heat exchangers and integrating heat recovery systems can improve FCC unit energy efficiency. By capturing and reusing heat generated during the cracking process, refineries can reduce overall energy consumption and enhance the economic viability of producing petrochemical products.

    Continuous investment in R&D can lead to the discovery of new catalysts, processes, and technologies that can further enhance FCC performance and its integration with petrochemical production. Investments in new pilot plant equipment, testing equipment or modifications to existing designs are often needed to support new R&D innovations.

    By focusing on these upgrade strategies, refineries cannot only boost their FCC unit’s efficiency but also enhance their capability to produce a broader range of valuable petrochemical products, aligning with market demands and economic trends.

     

    Jan-2025


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