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Considering the growing interest in maximising renewable and biomass feeds (including Fischer-Tropsch liquids) through the FCC, what are the most noticeable options you see refiners adopting beyond 2030? To what extent can renewable feed pretreatment be simplified (if at all)?

Mar-2023

Answers

Dharmesh Mahajan, Becht, dmahajan@becht.com

Various R&P Technology licensors are working deeply to develop and commercialize technology packages capable of converting low value agri-residues and surplus forest biomass into high value biocrudes these days through pyrolysis (catalytic/fast/slow) and hydrothermal liquefaction (continuous/sequential, etc.). Biocrudes produced through these pathways are energy dense liquid biomass molecules, which are easy and less expensive to transport to the refinery gate for processing.
Generally, transporting biomass beyond 100 Km radius of where it is produced in the fields, farms or forests make the conversion processes unsustainable on GHG reduction metrics, and unviable on commercial aspects. Consequently, these energy dense liquid biomass molecules offer plenty of opportunities to existing refineries for conversion of the waste resources and their intermediates to sustainable biofuels and reduce carbon footprint of refineries as well as that of end-users (cars, trucks, and fleet owners).

Such biomass-based biofuels has significant potential to reduce life cycle GHG emissions between 60% - 90% compared to fossil fuels. These highly valuable Low C.I. (carbon intensity) sustainable biofuel options help refineries meet or reduce their compliance liabilities.

These biocrudes are virtually carbon-neutral as the carbon available is in the carbon cycle through the nature’s process of recapturing CO2 through photosynthesis in plants. These biocrudes can be co-processed in conventional FCC units with proper pretreatment of these feedstocks and with certain modifications to produce drop-in partially sustainable fuels.

On pretreatment as well as FCC coprocessing front, multiple refinery owners and licensors have been working diligently in the last 2 decades, doing FCC coprocessing trials at commercial scale with varying percentage of biocrude being injected in FCC units. They have been trying to assess concerns related to integrating such pretreatment and processing scenarios into existing refining and downstream blocks.

These biocrudes pose significant challenges for processing due to their high moisture and oxygen content, severe pH levels and presence of contaminants such as chloride posing metallurgy and corrosion hurdles. Contaminant levels, especially metals observed in these biogenic feeds have different profile and percentages that are far different than what has been observed in fossil streams processed in these processing units. Certain properties such as viscosity of these biocrudes also become a challenge at lower ambient temperatures in winter.

Proper pretreatment methods are being developed, tested, and scaled up from lab to pilot plants to demo units and eventually to commercial FCC coprocessing trials through catalytic pyrolysis, sequential hydrothermal liquefaction, Solvent washing of the impurities to name a few. Many commercial trials and their achievements are also being announced with lot of efforts on different approaches to make it techno-commercially attractive besides being low carbon option.

Rewards associated with all such endeavors to make FCC co-processing of biocrudes techno-commercially attractive generally surpass the risks significantly, by offering:
1-   Compliance solution with significant edge to the refineries:
a. By production of sustainable/ partially sustainable renewable gasoline & diesel streams
b. Reducing overall carbon footprint of the company and its production sites
c. By achieving compliance targets through biofuel blending at refinery premises itself, with a pathway to generate and satisfy the EU RED / US LCFS requirements
d. By offering protection from market fluctuations and enabling energy security through utilization of domestic biogenic carbon molecules available through locally produced and sourced biomass, fats & vegetable oils; eventually reducing FOREX burden on the country and the company concerned due to reduction in fossil crude imports
e. By eliminating “blend wall” hurdles posed by oxygenated biofuels such as bioethanol and FAME biodiesel
f.   By production of Cellulosic RINs in the refinery complex itself (applicable to US based
     refineries).

2-   Compliance solution through low-cost revamps of existing refinery assets:
a.    Comparatively faster, better, cheaper alternative due to significantly lower cost revamps in existing FCC units
b.    By utilizing existing infrastructure available within refinery for production of fully fungible Biofuel blends

Overall, we acknowledge that there are valid strategic reasons for ever growing interest in maximizing renewable and biomass feeds through the FCC and hydrotreating assets available at existing refinery sites. With a limitation on availability of other biological feedstocks such as vegetable oil, used cooking oil and animal fats, and genuine concerns due to scenarios such as “Food vs. Fuel” BECHT strongly believe that agri-waste and surplus forest biomass offers best feedstock synergies for future ready bio-refineries producing sustainable renewable fuels at scale beyond 2030, if not before.

Mar-2023
Mel Larson, Becht, mlarson@becht.com

The value or use of bio mass synthetic feed to FCC is dependent upon the region and market credits. The type of bio synthetic processing has limitation that are defined by the contaminants and thus subsequent impact in the FCC yield. Organic chlorides will increase ammonium salt formation, some bios will create new forms of corrosion components and surfactants making treating more challenging downstream. There is not a one size fits all answer. Reliable availability, logistics of bringing bio mass to the plant, segregation, where to inject in the riser at what temperature are just a few of the questions to answer. As far as adaption, if the percentage of bio mass in feed can be tracked to the bio aspect of olefins to gain value as PC feed stock it may gain more value.

Mar-2023
Charles Brandl, Honeywell UOP, charles.brandl@honeywell.com

The most noticeable option for refiners adapting and maximising renewable and biomass feeds would be the increased availability of these feeds. As innovative technologies such as hydrothermal liquefaction (HTL), Fischer-Tropsch, and other pyrolysis oil technologies are developed and commercialised, these feeds will become more economically available. As refiners continue to drive for net zero targets, they can take advantage of the FCC unit as an ideal existing asset and a robust process to effectively co-process these non-fossil-based feeds at an increasingly higher amount, much beyond the typical 5 vol%. In FCC, pretreating the renewables feeds such that the physical properties (viscosity and temperature) are ideal for effective atomisation of the feeds within the riser is critical for complete conversion.

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

As always, it will depend on what products we want to obtain in 2030 from the FCC and the kind of biofeed to the unit. Although we use renewables as feed, it will have the same principle as fossil fuels, the carbon/hydrogen ratio of the feed vs C/H of the product that will be obtained.

So, if we want to obtain olefins, biofeed to the FCC should be hydrotreated to be able to convert it unless the biofeed is composed of paraffins, which so far does not happen. Most of the compounds obtained from the biofeed have a high content of aromatics or compounds with a carbon greater than 75% in their composition. These compounds generate a lot of coke in FCC or aromatics even more complex, and again the FCC feed will be hydrotreated before entering FCC units. Moreover, do not forget that CO2 emissions should be captured and/or transformed into other products.

Mar-2023
Theo Maesen, Chevron Lummus Global, tmaesen@chevron.com

An FCC will convert biomass into renewable naphtha, for which there are policy incentives in some parts of the world. Due to feedstock volume limitations, the size of an FCC typically limits renewable gasoline production to co-processing. In most parts of the world, stand-alone operations are more policy-enabled than the co-processing of biomass and fossil-derived feedstocks. Since the feedstock volumes suffice to hydroprocess biomass into renewable diesel and jet in a stand-alone operation, hydroprocessing is usually preferred over FCC.

Renewable feed pretreatment typically consists of multiple unit operations to make RBD (refine, bleach and degum) grade biomass. An alternate approach is a hydrothermal water wash to hydrolyse most of the gums. How effective this simpler approach is will depend on the feedstock portfolio.

Mar-2023