Hydrocarbon Processing - December 2022 - 21

Special Focus Catalysts
B.-Z. ZHAN, Advanced Refining Technologies (ART)/
Chevron Lummus Global (CLG), Richmond, California;
J. FRITZ, Chevron Lummus Global, Richmond, California;
and D. SOMERS, Advanced Refining Technologies,
The Hague, the Netherlands
Partners maximize profitability during the pandemic
The COVID-19 pandemic can be
viewed as one of the most challenging
periods in the history of the oil and
gas sector. Refineries worldwide faced
difficult times operating at their turndown
capacities or even temporarily
shut down units at the refinery. These
unforeseen circumstances have put significant
pressure on refinery volumes
and margins to survive in this challenging
market environment, forcing refiners
to improvise. Unprecedented quarantines
and lockdowns imposed due to
COVID-19 had a serious effect on fuel
demand and oil prices.
Since hydrocrackers are extremely
flexible, they play a vital role in optimizing
refinery economics. Hydrocrackers
convert the bottom of the barrel, upgrading
feedstocks into high-value fuels, lubricants
and chemicals, which boost the
value of refinery product slates. On top
of adapting to cyclical market demands
and the more stringent environment
IMO regulations in 2020, refiners needed
to act swiftly to remain competitive.
The recent decline in demand forced refineries
to run their hydrocrackers more
economically by changing to new operational
strategies to meet market demand.
Preemraff Lysekil case study. Preemraff
Lysekil is a conversion refinery
consisting of an atmospheric crude distillation
unit (CDU), a vacuum crude
distillation unit (VDU), a visbreaking
unit (VBU), a mild hydrocracking
unit (HCU), a fluid catalytic cracking
unit (FCCU), a hydrodesulfurization
unit (HDS), a catalytic reforming unit
(CRU), an isocracking unit (ISO),
and LPG units in addition to their hydrotreating
units (FIG. 1).
FIG. 1. Refining process at Preemraff Lysekil.
The product range varies from LPG to
heavy fuel oil. One diesel product is called
MK 1 Diesel, which is mainly applicable
to the Swedish market, and has a specification
on aromatics that must be < 5 vol%.
The Chevron Lummus Global
(CLG)-designed Preemraff single-stage
liquid recycle (SSREC) unit design
(FIG. 2) and the ART-designed catalyst
system enabled the Preemraff refinery
to adapt to changing market conditions
swiftly during the COVID-19 pandemic
to maximize profitability while continuing
to operate safely within design limitations.
This article will discuss how that
optimization of the SSREC hydrocracking
operation gives refiners opportunities
to improve performance in these
dynamic circumstances. With CLG as the
process licensor and ART as the technical
service provider and catalyst vendor,
the two companies' combined design and
catalyst expertise created an opportunity
to optimize the unit operation and maximize
profitability.
The CLG-designed ISO unita
was
designed in 2001 and built in 2004 to
FIG. 2. Simplified Preemraff ISO unita
configuration.
SSREC
tackle the new environmental legislation
in the EU, which set the maximum sulfur
content in gasoline and diesel to 10
ppm. The unit was originally designed
to process 385 m3
/hr of a mixture of
heavy atmospheric and vacuum gasoils
in a once-through configuration with
50 vol% conversion to make a range of
products, including full-range naphtha,
kerosene, diesel and unconverted oil
(UCO) for FCC feed. The unit design
also included an integrated 165-m3
/hr
distillate unitb
to make low aromatic content,
full boiling range diesel. Unit turndown
was targeted to achieve operation
at 60 vol% of the minimum design case
Hydrocarbon Processing | DECEMBER 2022 21
Hydrocarbon Processing - December 2022

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