Assessment of co-processing hydrodeoxygenated fast pyrolysis oil and vacuum gas oil in a fluid catalytic cracking unit

• Author / Creator

  Alizadeh, Ali

• The production of liquid biofuels from lignocellulosic biomass feedstock (e.g. forest biomass) has received special attention because these biofuels are carbon neutral, have flexible production and upgrading processes, and can be produced from feedstock that is widely available. The major challenge in the direct substitution of bio-crude or bio-oil for petroleum fuels is their physical properties and compatibilities with existing infrastructure. The potential to use them is limited due to their high water and oxygen contents, thermal instability, and high corrosiveness and viscosity. To improve the quality and physical properties of biomass-based oil, hydroprocessing and hydrocracking into liquid fuels is an option, but these processes require a large capital investment to build standalone units. One way to resolve the challenges in the upgrading of bio-oil is to co-process it with crude oil in a petroleum refinery and take advantage of existing facilities. Suitable biomass-based oil can be mixed with conventional crude oil and processed at the same facility. This offers several advantages, including reducing capital costs (i.e., compared to building a standalone bio-refinery) and blending at a several co-processing ratios, depending on the refinery unit’s ability to handle the bio-oil and the physical properties of the bio-oil.In this study, processing hydrodeoxygenetaed bio-oil from biomass fast pyrolysis with vacuum gas oil in a refinery’s fluidized catalytic cracking (FCC) unit was considered as the co-processing pathway. There have been many studies on the technical feasibility of this co-processing method, and the physical properties of hydrodeoxygenated bio-oil (HDO) show promising results for co-processing operations. A conceptual framework was developed to understand the associated costs of co-processing bio-oil with conventional crude and its effect on the FCC unit economics. A rigorous simulation model was developed to analyze the effects of adding new feedstocks to the refinery’s FCC units. The refinery operating conditions before and after co-processing operations were based on the developed simulation model and was used to analyze the cost effects of co-processing in a refinery operation.The simulation results show that by mixing 10 wt.% hydrodeoxygenated pyrolysis oil with vacuum gas oil, overall FCC unit CO2 emissions can be reduced by 4% with almost the same gasoline yield. The developed cost model shows that as a result of co-processing, gasoline and diesel production costs will increase by 6.8 ¢/litre and 2.7 ¢/litre, respectively, while almost the same amounts of these products are produced. Co-processing HDO with vacuum gas oil (VGO) is technically feasible based on earlier experimental studies and will introduce renewable content to refinery transportation fuels at the time of production. The information developed in this study could be used as a preliminary assessment of co-processing of bio-oil with conventional crudes.

• Subjects / Keywords

  • Co-processing; bio-oil; FCC unit; biofuels; renewable feedstock

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-ttxf-1s12

• License

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