By: Scott Sayles, Matthew Caserta, Stephen DeLude and Al Keller
Comprehensive review of corrosion operating concerns when co-processing renewables and bio-oils through existing hydrotreaters, FCC units, amine units, and other assets.
Below is an excerpt from an article recently published in PTQ Q3 2022 Issue (digitalrefining.com)
Renewable feedstocks: Processing Steps
The processing of renewable feedstocks in a refinery requires the following stages/steps:
• Feed selection
Each step has aspects unique to the feed being considered. An overview of production requirements indicates that biofuel production must consider the balance between food source utilization and managing climate change. Feedstock selection is also a policy decision between private and public sectors. The use of non-food sources is the preferred path towards renewable fuels. Renewable feed supply and availability are equally challenging.
Renewable feed requires oxygen removal and olefins saturation to produce fully fungible fuel components. As a result, hydrogen and hydroprocessing capacity must increase to accommodate additional demand. The economic incentive to produce renewable feeds depends on uncertain feed and product markets. Biofeed processing and co-processing may provide significant sustainability and economic benefits for fuels producers but may not be competitive without subsidies.
Biofeeds are not all the same. Specifications and quality control need to be established consistent with the chosen processing scheme. For example, if not stored properly, biofeeds can degrade quickly (bio-action). Biofeeds are successfully co-processed in refinery units but only up to unique constraints for each specific unit.
As biofeed concentration increases, increasing hydrogen demand, corrosion issues, and water/amine systems should be assessed based on selected processing options. These changes are predictable and can be effectively implemented with a proper engineering overview. The final renewable diesel or jet require blend recipes and/or additive requirements that will change (quality). The final blends must meet all product quality requirements.