Resid Conversion factory

Resid conversion (FLEXICOKING™)  

FLEXICOKING™ technology is a commercially proven, cost-effective, continuous fluidized bed process that thermally converts heavy feeds to lighter products and flexigas. FLEXICOKING technology, as an integrated process, offers great flexibility when upgrading residuum, as it provides high-value liquid products as well as clean flexigas that can be used as refinery fuel or for power generation.

Key benefits

  • dollar sign

    • Simple integrated steam/air gasification and carbon steel construction
    • Reduced plot space requirement

  • dollar sign

    • Continuous non-batch operation and closed coke handing system, resulting in low emissions

  • dollar sign

    • Handles a wide variety of feeds

resid conversion quiz

Test your knowledge

Resid conversion technology has been commercially proven for nearly 40 years, but how much do you know about what it could do for your business?

Take the quiz

How FLEXICOKING technology works  

The vacuum resid feed enters the scrubber for “direct-contact heat exchange” with the reactor overhead product vapors. The higher boiling-point hydrocarbons (~975°F+/525°C+) present in the reactor product vapors condense in the scrubber and return to the reactor, in mixture with the fresh feed. Lighter overhead product vapors in the scrubber go to conventional fractionation and light-ends recovery. The feed is thermally cracked in the reactor fluidized bed to a full range of gas and liquid products, and coke. Coke inventory is maintained by circulating the bed coke from the reactor to the heater via the cold coke transfer line.

In the heater, the coke is heated by the gasifier products and circulated back to the reactor via the hot coke transfer line to supply the heat that sustains the thermal cracking reaction. The excess coke in the heater is transferred to the gasifier, where it reacts with air and steam to produce flexigas. The gasifier products, consisting of flexigas and coke mixture, return to the heater to heat up the coke. The flexigas exits the heater overhead and goes to steam generation, to dry/wet particulate removal, and to desulfurization in the integrated FLEXSORB™ process. The clean flexigas is then ready for use as fuel in refinery boilers and furnaces and/or for steam and power generation.

Only a small amount of product (1% weight on Fresh Feed) is collected as fines from the flexigas and purged from the heater to extract feed metals.


Full range products slate  

FLEXICOKING technology produces a full range of products, from a C1+ reactor gas to C5/975°F (525°C) liquid products, the multi-purpose flexigas and a small stream of low-sulfur coke that is purged to extract feed metals.

FLEXICOKING technology services include:  

  • Initial consultations
  • Development of licensing proposal
  • Basic engineering package, including basic design specification and operating guide
  • Engineering support during FEED and EPC stages
  • Technology transfer, training and startup support

Featured resources

View highlighted news, events, technical papers and case studies below. To see our full collection of resources, browse our Library.
  • ExxonMobil Chemical Library icon

    FLEXICOKING™ – A visual view

    An infographic offering the advantages of FLEXICOKING™ resid upgrading technology compared to delayed coking.

    Learn more
  • ExxonMobil Chemical Library icon

    ExxonMobil awards FLEXICOKING™ technology license to Sinochem Hongrun Petrochemical Co. Ltd.

    Exxon Mobil and Sinochem Hongrun announce the sixth new FLEXICOKING™ unit licensed in seven years, targeted for startup in 2020.

    Learn more
  • ExxonMobil Chemical Library icon

    FLEXICOKING™ technology resid conversion solution for refinery energy optimization

    ExxonMobil’s FLEXICOKING™ resid upgrading technology process lowers emissions and produces clean flexigas that can help lower facility energy costs. Greek refiner Hellenic Petroleum achieved significant environmental and cost benefits by implementing the technology.

    Learn more
  • ExxonMobil Chemical Library icon

    Market insights on the crude-to-chemicals trend: Refining the product slate

    Based on a detailed analysis, this study results show FLEXICOKING™ technology can offer lower capital investment, lower operating cost and lower environmental emissions with a better economic fit to the chemicals run plan.

    Learn more
  • ExxonMobil Chemical Library icon

    Executive viewpoint: The need for change—Why the industry is looking at crude-to-chemicals

    This article is part 1 of a 2-part series. Contributed by the president of ExxonMobil catalysts and licensing LLC, this first article provides an overview of the drivers creating the shift in the Crude-to-Chemicals market. Read more

    Learn more
  • ExxonMobil Chemical Library icon

    Executive viewpoint: The opportunity for greater growth and value - considerations for crude-to-chemical projects

    This article is part 2 of a 2-part series. Contributed by Dan Moore, president of ExxonMobil catalysts and licensing LLC, the article provides an overview of the opportunities for greater growth in crude-to-chemical projects.

    Read more
  • ExxonMobil Chemical Library icon

    FLEXICOKING™ technology helps refiner substantially reduce energy costs and achieve environmental benefits

    A Greek refiner reduced dependence on fuel oil and reduced emissions by switching to ExxonMobil’s FLEXICOKING technology.

    Read more
Don’t see what you’re looking for? Check out Quick links to explore additional content.
Loading