Revamps 2025 Issue

Renewable fuel demand vs available feedstock, Mtoe/yr, 2023-30

82 15%

Gap: 15 Mtoe/yr

67 25%

54 20%

30%

75%

55%

80%

70%

Esta b lished feedstock (oils & lipids)

Fuel demand

Estimated fuel demand

2020

2021

2022 2025 2028 2030

2023

2030

Used cooking oil & animal fat Sustainable aviation fuel demand

First - generation oil crops Renewa b le diesel demand

U.S.

Other North American

Europe

Asia

South America

Rest of the world

Additional global potential

Biodiesel demand

co-processing units must either install pretreatment units (PTUs), which are likely not capital-effective, or purchase pretreated renewable feedstocks. PTUs will typically comprise acid degumming and water washing, followed by drying and bleaching steps. It must be cautioned that feedstock quality assurance and assay can be questionable in some import/export cases. Both in the US and EU, UCO from China has been called into question for being fraudulently diluted with palm oil, an unwanted high CI component. The US EPA has investigated, and EU certification rigour is consequently increasing. Triglycerides have lower thermal and oxidative stabil- ity than fossil feedstocks, which may pose storage prob- lems, such as changes in density, viscosity, acidity, and an increase in polymer formation. The polymer formed during the storage of triglycerides can lead to gumming in heat exchanger tubes and transfer lines. Triglycerides also have corrosive properties attributable to carboxylic acids. Storage tanks should be made from compatible materials, such as stainless steel, aluminum, fluorinated polyethylene, and fibreglass, to prevent reac - tions that could degrade the fuel. Certain materials should be avoided, such as uncoated mild steel, copper, brass, lead, tin, and zinc, as they can react and cause contamina- tion. Storage times should be as short as feasible, looking to maximise tank turnover. Best practices recommend the nitrogen blanketing of renewable feed storage tanks. Figure 4 UCO supply scenarios 2025-2030 7 ( Source: LMC International Global Data, UCO Supply Outlook, Sep 2023 )

Figure 5 Demand vs available feedstocks for renewable fuels 8

Chemistry implications, H₂ consumption, heat release, catalyst systems For fossil fuel refiners, a direct entry into renewable diesel and SAF production is to take advantage of existing hydro- processing units, appropriately adapted, to co-process some fraction of renewable feedstocks with petroleum feedstocks. Co-processing in hydrocracking and distillate hydrotreating units is an option that has been actively employed in refining scenarios for more than a decade. Considering the chemistry of lipid feeds and required oxygen removal and olefin saturation, there are a number of new challenges in comparison to petroleum hydropro- cessing units. These units must have tailored guard cata- lysts and operating adjustments to assure the integrity of a catalyst load cycle and mitigate effects from contaminants, such as alkali and alkali earth metals, as noted previously, and high acid content, as well as the strong phosphorus poisoning effect derived from phospholipids. Catalysts selective for optimised hydrodeoxygenation (HDO) will likely be part of a new catalyst system. The unit could require some level of revamp expenditures to address the variance in feed acidity, higher product paraffin content, and the need for adequate hydrogen supply and tempera- ture control to handle the concurrent reaction exotherms arising from higher oxygen and olefin content. The increase in off-gases (propane, CO, CO₂) will drive higher gas recycle rates and hydrogen addition rates to address higher purge rates required to keep CO levels mod-

erated and hydrogen treat gas purity adequate. CO is not removed by the amine scrubber in the same way CO₂ is, and CO is a catalyst activity inhibitor. The combination of water and CO₂ produced can yield carbonic acid downstream and needs to be properly mitigated. At the same time, renewable feeds with high levels of free fatty acids pose corrosion issues in the feed systems analogous to high total acid number (TAN) fossil feeds.

Contaminant levels and specification range for HEFA processes

Raw feed

FFA, %

P, ppm Metals, ppm

Cl, ppm Polyethylene, ppm

Vegetable oils

<3 <6

5-250 15-30

100-300

- -

Palm oil

20-60

<15

UCOs

1-10 2-35

<20

<50

20-100 50-500

0-200

Animal fats

50-1,000 200-2,000

0-1,000

Technology provider specs

5-20

2-3

5-10

5-50

Table 2

Revamps 2025