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.