Corrosivity and Thermal Stability of Biocrude Oil for Co-Processing in FCC Feedlines: An Investigation and Risk Assessment

• Author / Creator

  Pedraza, Henry B

• Fast pyrolysis bio-oil is a promising renewable energy source derived from biomass. However, its high corrosivity and poor thermal stability have limited its widespread use as a drop-in fuel. One promising method for transforming low-quality biocrudes into drop-in fuels is co-processing with petroleum intermediates in existing fluid catalytic cracking (FCC) units. Co-processing BO with petroleum intermediates in FCC units requires careful consideration of the corrosion resistance from the feed injection system and the BO thermal stability, particularly since feedstocks are usually preheated to 100–300 °C before injection. In this study, we investigated the corrosion resistance of several structural materials commonly used in FCC units, including carbon steel (CS), chromoly steel (P91), stainless steels (SS) 304L and 316L, and a nickel-based alloy (HX), and the aging risk of BO at a temperature range of 80–220 °C. Our results showed that CS performed poorly at each testing temperature, exhibiting severe corrosion. In contrast, P91 showed a lower corrosion rate of 3.497 mm/y at 80 °C for 24 hours, but its corrosion rate increased as the temperature increased. In the immersion experiment at 220 °C, the corrosion rate of P91 surpassed that of CS, reaching a value of 73.32 mm/y. SS 304L and 316L exhibited an acceptable corrosion rate of 0.29 mm/y and 0.06 mm/y at 80 °C, but their corrosion rate increased dramatically as the temperature increased. HX was not affected at any of the studied temperatures. As to the thermal stability, we observed the occurrence of phase separation, with BO separating into liquid and solid phases at all three temperatures. As the temperature increased, we noticed a significant change in the physicochemical properties of the phases. Furthermore, one critical finding from our study was the identification of a temperature threshold of 80 °C. At this temperature, we observed both active corrosion of steels in BO and fast aging of the BO.

• Subjects / Keywords

  • Corrosion
  • Co-processing
  • Bio-oil
  • FCC unit
  • Materials Engineering

• Graduation date

  Spring 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-nzvn-kb36

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.