Thermal/acid catalised water removal Partial deoxygenation results in aldehyde and ketone formation Reduces H/C ratio of products
High coke and low biogenic carbon recovery
Dehydration Water + coke (biogenic)
Biogenic coke formation
Rejects biogenic carbon and hydrogen f ro m system
Oxygen rejection as CO and H O Reduces H/C ratio of products
Decarbonylation Water + CO (biogenic)
Coke formation
O
Higher slurry and coke production from bio-oil and conventional feed
R + CO + H O
HO
R
Highest biogenic carbon retention in products Increased coke from conventional feeds
Oxygen rejection as H O Hydrogen donation from conventional feeds
Hydrodeoxygenation Water + coke (oil)
Max biogenic carbon recovery
O
R + 2H O
HO
R
Minimises hydrogen loss from products with minimal coke Biogenic carbon rejection as CO
Oxygen removal as CO Retains H/C ratio of products
Decarboxylation CO (biogenic)
Max products
O
R + CO
HO
R
Minimise products with minimal impact on product slate? OR Maximise biogenic carbon in products?
The Inherent Con ict:
Figure 3 Major deoxygenation pathways influencing coprocessing of oxygenated feeds
H₂ consumption, so the first limitation to increase the bio - feed intake is set by the MUG compressor capacity. The second operational aspect to evaluate is the maximum delta T allowed. This is generally set by the reactor design. However, this limit can be managed up to a certain extent (by recycling the product and diluting the feed, for example). Additional flexibility is also provided by the quench, with more impact on subsequent beds than the top bed but also on overall T profile. There are also some hardware limita - tions that might require revamp and modifications. The first one is related to the high acidity of the biofeed that can lead to corrosion problems upstream and within the reactor. In general, there are some minor preventative actions available to mitigate this (such as pretreatment of the biofeed and N₂ blanketing in the biofeed tank). In more severe cases, chang - ing metallurgy upstream might be the only option. A second hardware limitation can be the formation of salt downstream caused by the presence of Cl in the biofeed. In this case, wash water injection can be applied to mitigate this complication. The last aspect to consider is the formation of certain byproducts upon biofeed coprocessing. It is recommended to confirm that the high-pressure separator has sufficient capacity to deal with the amounts of propane and water formed. On the gas-make side, a series of components will be formed (methane, CO, and CO₂) that will impact the recy - cle gas purity. For this reason, it is recommended to increase the purge rate compared to a conventional operation. Q What process and operational areas have refiners demonstrated a positive ROI in the application of artificial intelligence and machine learning strategies? A Heather Gilligan, Senior Hydroprocessing Engineer, heather.gilligan@imubit.com, Imubit Artificial intelligence (AI) and machine learning strategies
are being applied across all process and operational areas in many different business applications. Some have been in place for many years, such as machine learning to find anomalies in the operation of rotating equipment as part of predictive maintenance. However, it was only recently that AI and machine learning strategies moved from an advisory capacity to closed loop, where an action is automatically executed as a result of the AI model calculation. In this newer world of closed-loop AI optimisation, Imubit is seeing refiners capture the highest value when applying the technology to complex and nonlinear pro - cesses. Some notable applications include conversion units, such as FCCs and hydrocrackers, and multi-unit feed and multi-unit product optimisation. One example of the latter involves balancing T90s across multiple units to push the diesel pool to the T90 limit and upgrade molecules from gasoil. Some of the quantified benefits that have been reported publicly by customers using closed-loop AI optimisation include: • 0.5°F improvement in average ULSD T90 vs baseline (reported by Delek US at 2024 AFPM Summit) • 2% FCC debutaniser tower throughput capacity increase, removing bottleneck and allowing them to push FCC con - version (reported by Big West Oil in June 2024 Imubit webinar) • FCC liquid volume yield improvement of 0.6% (reported by Big West Oil in June 2024 Imubit webinar). • Reduced conservatism in diesel flash target by 2°F, enabling increased, on-spec, diesel throughput (reported by Big West Oil in June 2024 Imubit webinar). • 25% reduction in sub-optimal coke drum cycles sig - nificantly reducing coker giveaway (reported by Marathon Petroleum Corporation Garyville Refinery at AFPM Summit 2024).
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PTQ Q1 2025
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