A. Fernández, A. MENA and C. RIVAS, bp Energía España Castellón refinery, Castellón, Spain; M. BESCANSA and R. GONZÁLEZ, W. R. Grace, Spain
Oil demand is expected to reach record highs this year1 after a sharp rebound following the COVID-19 pandemic. Reduced post-COVID refining capacity has contributed to further tightening of the supply/demand balance as the world is quickly returning to normality. On top of this, the Ukraine conflict that started in early 2022 has exacerbated this strained supply scenario, causing major curtailments in oil and gas trade, which, in turn, has prompted an unprecedented increase in energy prices across the globe. Through these complex times, the refining sector remains a critical part of the energy industry, acting as a crucial provider of liquid fuels and chemical precursors to secure the fulfillment of society’s demands.
When looking ahead to the near future, the current energy crisis triggers a reflection on whether governments will support a slowdown of the ongoing energy transition, or whether they will instead catalyze shifts toward a more decarbonized energy framework. Looking at the response from many governments around the world, several regulations and programs have been enacted, including the U.S. Inflation Reduction Act, the Fit for 55 package and REPowerEU in the European Union (EU), Japan’s Green Transformation program, and the ambitious clean energy targets in Korea, China and India. These suggest that a faster decarbonization of the energy mix will be the path chosen to bolster a more diversified and robust energy system, while reaching the carbon dioxide (CO2) emissions reduction commitment for a 1.5°C global warming by 2050 (FIG. 1).2
Refining integrated hubs for low-carbon energy supplies. Even though oil demand is expected to peak and then decline in the decades to come, the refining industry is expected to remain as a key supplier of low-carbon liquid fuels and petrochemicals through 2050 and beyond. In February 2020, bp set out a strategy to be a net-zero company by 2050 and to help the world reach net-zero. This strategy has three focus areas: resilient hydrocarbons, convenience and mobility, and low-carbon energy. Two years later, bp revised the progress of these strategic goals, including a more ambitious target to reduce Scope 1 and Scope 2 emissions from its operations by 50% by 2030, compared with the initial aim of 30%–35%, while also reducing to net-zero the lifecycle emissions for energy products sold by 2050—an increase from the initial aim of a 50% reduction vs. a 2019 emissions baseline.
To attain such ambitious goals, bp aims to convert its current refineries into integrated energy hubs. In such hubs, various hydrocarbons and low-carbon feedstocks are converted into valuable products, taking advantage of low-carbon energy to power the asset and surrounding industry. In essence, it is a refinery with expanded green operational elements adapted regionally, which may include biofuels, wind, solar or hydrogen, among others.
The key role of biofuels in the energy transition. The energy transition is broadly envisioned as a combination of multiple different elements that will result in an energy mix that will satisfy both the increasing global demand, as well as the sustainability targets. Among them, there is a significant opportunity for biofuels contribution, particularly in the transport sector.
Biofuels are obtained from low-carbon feedstocks to achieve a significant reduction of the CO2 emissions associated with both the manufacturing and use of refined products commonly used in transportation. According to recent studies on biomass deployment and availability in the EU, within the context of the EU’s strategic framework Vision 2050, the deployment of advanced biofuels for the EU transport sector could be effectively realized with no availability constraints, provided that the right framework conditions to leverage the full potential of the whole bioeconomy are put in place.3 Considering near- and mid-term practices, the co-processing of complex biogenic oils in petroleum refineries can play a significant role if technical hurdles are solved.
Indeed, there has been intense activity in the refining industry to introduce biogenic oils into the refinery diet and convert them into liquid fuels and chemicals. The different processing routes explored include the option of the fluid catalytic cracking unit (FCCU), which breaks heavy, low-value hydrocarbons into lighter, higher-valued molecules used as liquid fuels and chemical precursors. The FCCU is well known for being one of the most flexible assets in a refinery, as it can swiftly adjust both product slate and/or feed properties over a wide range. This positions the FCCU as a promising outlet for several new potential non-fossil feedstocks—either directly obtained or recycled residual oils from industrial processes—in line with refinery decarbonization targets. As shown in TABLE 1, several types of feedstocks have been considered, with a wide range of properties and contaminants.
The operating versatility and feed flexibility of the FCCU give it huge potential to crack a wide range of different feedstock types. The co-authors’ company has conducted extensive research and development work for the last several years at pilot plant scale to determine the potential impacts to yield structure and operations in commercial units.4 Pilot plant testing reduces risk and uncertainty by identifying the optimum feedstocks and process conditions on a small scale so that fuel and petrochemical manufacturers can maximize their profits on the large scale.
Minimizing risks in the pilot plant. As part of corporate decarbonization goals, the bp Castellón refinery started to explore ways to reduce the fossil fuel input in its FCCU by introducing alternative biogenic sources into the unit’s diet. For that goal, the refinery decided to partner with the co-authors’ company as the FCC catalyst technology supplier. The bp Castellón refinery is in northeast Spain and has a nameplate crude capacity of 110,000 bpd. It has a 30,000-bpd FCCU with an ExxonMobil Flexicracker design, operating in full burn mode. The FCCU’s feedstock is typically a blend of primarily vacuum gasoil (VGO) together with several other streams—such as heavy coker gasoil (HCGO), distillation overflash and atmospheric residue (flash tower bottoms)—and is sometimes complemented with imported VGO. After years of leading projects to minimize their environmental impact in reducing air emissions,6 the unit’s team embarked on a journey to defossilize the FCCU.
The initial approach was to scout potential first-generation biogenic oils and to analyze the impact that processing such feeds has on the yield structure, under the typical conditions of the commercial operation. First-generation biofuels are those that are produced from edible energy crops such as sugar-based crops (sugarcane, sugar beet, sorghum), starch-based crops (corn, wheat, barley) or oil-based crops (rapeseed, sunflower, canola), among others.7 First-generation biofuels make up most of the biofuels that are now is use.
Two different vegetable oils were selected (named Bio-1 and Bio-2): their main properties are summarized in TABLE 2. In general, observed properties in terms of density, sulfur or concarbon are within the usual ranges of a typical VGO. The Bio-2 sample showed a high content of Na (4 mg/kg), and small amounts of Ca and P in both oils. The simulated distillation data were shifted to higher boiling points for the two biofeeds compared to the VGO base, with an apex of ~610°C for Bio-1 and ~620°C for Bio-2, most likely reflecting the different triglycerides in these oils. Both biofeeds were easily miscible, with the base VGO employed at all concentration levels, and no particulates or deposits were observed.
In general, first-generation biogenic oils are relatively easy to crack under the conditions of an FCCU, yielding good levels of conversion. The primary operational challenges, though, may come from the handling of molecules containing oxygen, as well as unconventional metals present, sometimes at very high values. Four different blends were prepared using different biofeed contents and types, as shown in TABLE 3. The blends were cracked in a single receiver, short-contact-time microactivity (SR-SCT-MAT) pilot plant specially designed for the testing of biofeed samples, including a receiver to capture liquids (FIG. 2).8 In addition to hydrocarbon products, coke and hydrogen sulfide (H2S), the specially designed equipment allows a mass balance including the oxygen-containing compounds, carbon monoxide (CO), CO2, water (H2O) as a liquid and a gas, and oxygenated products in the gasoline to the light cycle oil (LCO) fraction of the syncrude. This way, the oxygen-containing compounds are included in the converted products. Unfortunately, CO was not determined in this study due to an unexpected technical defect on the gas chromatography (GC) that occurred during the tests. CO amounts are typically found in the same range as the CO2 yields for the first-generation biofuels.
A representative equilibrium catalyst (Ecat) sample from the FCC commercial unit was used for all the feedstocks, and the testing was performed considering typical operating conditions. The results indicated good crackability of the biogenic oils, as expected from the physical-chemical properties (FIG. 3), with slightly higher Grace Value Conversion (GVC). GVC is a redefinition of conversion for enhanced carbon monitoring (FIG. 4), as it enables a better alignment of FCCU CO2 emissions with the production of high-value products.9 The yield structure did not change significantly, as can be seen in TABLE 4, but some shifts were observed:
Oxygenate management is crucial for a smooth operation, so it is important to quantify the oxygen-containing compounds and their nature. As expected, higher oxygenate levels were observed when increasing the biofeed concentration (FIG. 5). Oxygenate distribution was provided to better understand the potential outlets of these molecules, and to plan the actions needed to prevent any operating issues (TABLE 5).
As legislation around biofuels evolves, the use of vegetable oils is being heavily debated—in particular, those that compete with food crops or that cause an undesirable environmental impact like deforestation or water stress. For that reason, many refiners are also considering the option of processing second-generation biofeeds and/or recycled waste oil streams, such as waste/used cooking oil (WCO/UCO). In general, second-generation biofuels are those obtained from pyrolysis of lignocellulosic feedstocks, which have the potential for co-processing in units like an FCCU but may require some pretreatment to minimize the significant impact in yield slate10 and/or require specific hardware to avoid plugging and/or corrosion issues.11
As a follow-up of the initial study, with the aim of expanding the scope of non-fossil fuel options for feeding the FCCU, the authors embarked on a second test of a WCO to evaluate its impact on the unit operation and yields. The WCO sample used for the study was easily mixed with VGO and did not result in any miscibility issue or deposits. Looking at the properties of the VGO-WCO blends (up to 10 wt%), the main shift observed was the increase of the concarbon with the WCO content. No unconventional metals were identified in significant amounts, while the spread of aromatics vs. paraffins and naphthenes suggested potentially good crackability.
The results in the pilot plant revealed that blends of up to 10 wt% showed no conversion loss (FIG. 6). The primary potential issue could be an increase in coke yield, consistent with the higher concarbon observed. Other observations included slightly higher dry gas and propylene, somewhat higher LPG at lower olefinicity, and lower bottoms yield upgraded to LCO and gasoline, which could reflect the better crackability of the WCO employed (TABLE 7). Like the previous study using vegetable oils, the oxygen in the feedstock mainly produced H2O, CO and CO2, as well as some oxygenates in syncrude (gasoline and heavier liquid products).
A real case in the biofeed co-processing journey. The encouraging results—based on the technical discussions held and the results of the pilot plant—compelled the bp Castellón refinery team to proceed with a commercial co-processing trial of a biofeed in their unit. Several prevention measures were put in place to avoid operational issues. The trial was conducted over a period of more than 10 d to ensure that reliable data would be obtained, employing different levels of biofeed stepwise up to the highest levels tested at the laboratory. No increase in emissions was observed. There were no signs of fouling in critical parts of the system during the length of the trial. The expected increased amounts of H2O, CO and CO2 were obtained and properly managed in the corresponding treatment units with no major issues.
Overall, as no severe operating issues or unit performance deterioration were detected, the trial was considered a success, and it consequently confirmed the feasibility of co-processing biogenic feeds in the FCCU at commercial scale.
Looking at the future. The authors’ organizations partnered to explore various options to defossilize the bp Castellón refinery’s FCCU by reducing the consumption of traditional oil-derived feedstock by blending biogenic and/or residual oils. The extensive laboratory testing work, coupled with technical support, was extremely valuable to determine potential operational risks and to also preview yield shifts and performance impacts—both helped the refinery team to better plan the trial and anticipate potential adjustments.
After this positive experience, the refinery is planning to further expand ways to decarbonize its FCC operations. This may include increasing biofeed content and/or exploring alternative second-generation biofeed types (e.g., pyrolysis oils). Through close collaboration between the bp Castellón refinery team and its catalyst supplier, the authors believe that the FCCU will continue to be a crucial conversion asset in sustainable refineries of the future. HP
LITERATURE CITED
Andrea Fernández is an FCC and Merox Process Engineer for bp. She joined bp in 2020 as a Process Engineer for the treatment units. Since mid-2021, she has been working as an FCC Process Engineer. In Spain, Fernández earned a chemical engineering degree from the University of Santiago de Compostela, along with a specialized MS degree in industrial chemical engineering from the University of Alicante.
Apolo Mena is a Production Engineer for bp. He works as a Production Engineer in the conversion area of the Castellón refinery. His career began in 2001 as a Field Operator, and he became a Conversion Supervisor 8 yr later. From 2019–2022, Mena was a Shift Superintendent.
Carlos Rivas is responsible for the renewable fuels business at bp’s Castellón refinery. He started his career at bp in 2010, and has held different roles in technical, operational and commercial areas. Since 2018, Rivas has focused on how to increase renewable fuels and circular feedstock footprints.
María Bescansa Leirós is a Technical Sales Manager for Grace FCC and ART Hydroprocessing, covering Spain, Portugal and parts of Romania within Grace’s Europe, Middle East and Africa region. She has 19 yr of experience in the refining industry, previously working at the Repsol La Coruña refinery in northwest Spain. Leirós has held various roles within Repsol, most recently in the FCC area, but always related to catalytic processes. She led the team that developed the first ISO 50001 awarded to a refinery. In Spain, she earned an MS degree in chemical engineering from the Universidad de Santiago de Compostela, along with an MBA degree from the Universidad Nacional de Educación a Distancia.
Rafael González Sánchez is the Regional Marketing Manager, Asia-Pacific and India, for Grace. A chemical engineer, he has more than 17 yr of multidisciplinary experience in catalyst design and development, technical services, account management and marketing. Dr. González joined Grace as a research and development researcher, leading new FCC catalyst and ZSM-5 additive developments. He then became a Regional Technical Sales Manager prior to joining the marketing team. Dr. González is a co-author of several publications in the FCC industry field. He earned a PhD in engineering and advanced technologies from Universitat de Barcelona, and an Executive MBA degree from the EAE Business School in Barcelona.