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Considering market shifts favouring petrochemicals (for example, chemical-grade propylene), what are the optimal unit configurations and combinations, such as FCC/hydrocracking, for increasing high-margin products while reducing low-value streams, such as high sulphur fuel oil (HSFO) and low sulphur fuel oil (LSFO)?

Mar-2023

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Charles Brandl, Honeywell UOP, charles.brandl@honeywell.com

Optimal unit configurations for reducing or even eliminating low-value refinery streams like HSFO and LSFO are determined on a case-by-case basis, as this mainly depends on the existing assets/refinery configuration, feed sources, total investment, bankability, and price sets. That said, several optimal configurations can be considered, all of which can be classified into two categories: hydrogen addition and carbon rejection-based configurations.

Conventionally, carbon rejection configurations (SDA + (R)FCC or DCU + (R)FCC)) were typically deemed more economically viable in regions with high hydrogen prices and/or large gasoline markets.

However, considering the, energy transition, which involves the switch from fuels to maximum petrochemicals, decarbonisation and the hydrogen economy, hydrogen addition configurations typically are the preferred choice. This does not mean carbon rejection schemes can no longer be the right solution. For example, when hydrotreating the FCC feed, adding UOP’s latest generation high-propylene FCC (referred to as Flexible Propylene FCC) in addition to extracting aromatics from the heavy naphtha, and reducing the FCC carbon footprint, a lot of the investment criteria in today’s environment can still be met.

For hydrogen addition refinery configurations, several hydrogen addition schemes have been developed. The ones with the highest economic performance expressed as IRR and NPV are typically a combination of SDA or Uniflex (UOP’s slurry hydrocracking technology) + hydrocracking + integrated olefins suite (IOS) + steam cracker and Oleflex (UOP’s propane dehydrogenation [PDH] technology). UOP’s proprietary IOS is a collection of technologies to efficiently integrate and optimise performance of petrochemical complexes in three ways:
- Improve feed quality to steam crackers and catalytic reforming units to maximise the yield of high-value products
- Process propane in a PDH unit instead of a steam cracker to significantly boost olefin yields
- Increase, decrease, or eliminate most by-products to match the operator’s business strategies.

Mar-2023
Nieves Álvarez, MERYT Catalysts & Innovation, nalverez@meryt-chemical.com

The optimal reduction of HSFO and LSFO streams goes through more units than simply hydrocracking and FCC. These include completing the conversion section with coker units and possibly recycling the streams from this unit back to hydrotreatment and FCC.

Additional options include high-pressure hydrotreatment of heavy fractions (upgraders), such as HDH, Husky, and slurry beds, but they are also more expensive processes in terms of Opex and Capex.

Several technology companies in the market offer other processes, such as deasphalting with solvents, solvent extraction, and solvent dewashing, if refineries can process the solids generated.

In the future, it seems that the use of hydrocracking, residue fluid catalytic cracking (RFCC), and coker could be advantageous if FCC CO2 emissions can be captured and converted with biohydrogen, green hydrogen towards e-fuels, olefins, and aromatics. Of course, each of these alternatives will depend on the crude oil processed in the refinery, its product market and, most importantly, the capital investment the refinery is willing to make.

Mar-2023
Arun Arora, Chevron Lummus Global, arun.arora@lummustech.com

The optimum configuration depends on global, regional, and local economics. While finalising the optimal configuration, it is critical to consider optimum use of H2 (avoid product giveaways) and integration of similar pressure level units. The integration offers Capex and, more importantly, energy efficiency, which is critical going forward. The availability of online training simulators and other digital solutions (where licensor input can be integrated) is also key for large, integrated complexes to realise maximum value from the investment.

A few selected optimum configurations are depicted below. The configuration for each refiner and objective is not limited to the following. The available technologies can be rearranged to meet the desired objectives. The key is to have experts in these technologies working together to offer optimum solutions and access to hundreds of proprietary technologies:
For maximising chemicals as objectives – either as a standalone or ‘bolt-on’ project for an existing refinery (see Figure 1)
- For existing refineries with a large coker making ‘petcoke’, the resid upgrader can help to upgrade coke to higher value green or anode coke (see Figure 2)
- Needle coke for graphite electrodes – adding a new coker to make needle coke can offer attractive returns, especially if the right feed such as FCC slurry oil and/or coal tar is available
- LC-Fining with integrated HCR or HDT – a commercially proven configuration
- LC-Max with integrated HDT or HCR for maximum conversion
- RDS + FCC can be another configuration if the objective is to maximise very low sulphur fuel oil (VLSFO), but this configuration is crude slate dependent.

There are alternate new schemes for the objective available if plot space is limited and/or catalyst life is desired
- Single Regenerator Dual Catalyst (SRDC).

Mar-2023