Hydrocarbon Processing - April 2021 - 41

Special Focus

Clean Fuels
B. KLUSSMANN, Rigby Refining LLC,
Houston, Texas

A solution to the IMO 2020 MARPOL
Annex VI requirement
On January 1, 2020, a new requirement
limiting the sulfur content of marine fuel
to a maximum of 0.5 wt% went into effect.
The International Maritime Organization's
(IMO's) 2020 MARPOL Annex VI rule
globally prohibits ships from operating
while using a fuel with more than 0.5 wt%
sulfur without an exhaust gas scrubber.
Most ship engines in service were designed to operate with ISO 8217-compliant high-sulfur, heavy residual fuel oil. Historically, ISO 8217-compliant fuel oil is
generated by combining various high-sulfur refinery residues with varying percentages of cutters, vacuum gasoil (VGO) and
gasoil until the fuel specification is met.
From the perspective of marine engine
design firms and shipowners, the most
desirable way to comply with the new regulation would be to use a heavy residual
fuel oil that meets the ISO 8217 fuel specification and has a sulfur content of less
than 0.5 wt% sulfur. An early recognition
for such a fuel oil led to the development
of a proprietary upgrading processa several years before the IMO 2020 rule took
effect. Since the patented very-low-sulfur
fuel oilb (VLSFOb), which was made using this proprietary process, maintains
ISO 8217 bulk properties, it reduces the
risk of engine performance problems related to fuel oil blending.
Due to the COVID-19 pandemic, the
decline in demand of transportation fuel
resulted in an excess of distillate materials-and in the refinery streams used to
produce those same distillate materials.
The excess of distillate and intermediate refinery products drove the industry
toward blending distillate fuel oils or
blending distillate materials with residual
materials to adhere to the IMO marine
fuels regulation. A wide range of problems related to such VLSFO blends avail-

able in the market are being reported in
literature.1,2,3 From sludge formation,
engine damage, safety concerns and
pollution to increased soot and dumping of sludge, the new VLSFO formulations are creating significant safety and
performance concerns for the shipping
industry. Distillate blends may cause
wear and tear to ships' engine systems,
as their bulk properties can be adversely
affected when distillates are mixed with
residual materials. Because the proprietary VLSFO is created solely through
hydroprocessing, the resultant product is
compliant and homogenous.
While installation of scrubbers on
ships is an alternative to using VLSFO,
scrubbers present significant issues, including complex operation, costly maintenance, emissions violations, bans on
open-loop scrubbers in some ports, and
disposal issues for toxic byproducts and
sludge.4,5,6,7,8,9
The patented upgrading process.
Refining processes have historically focused on breaking down and upgrading
residual material to create higher-value
distillate products. Counter to traditional
residue upgrading technologies, the proprietary upgrading process intentionally
maintains the bulk properties of residual
fuel that make it the preferred fuel of the
shipping industry. The patented technology is rooted in commercially proven
refining processes, utilizing an alternate
approach counter to traditional refinery
residual material upgrading processes
such as hydrocracking, deasphalting and
coking. Because the proprietary upgrading process does not focus on cracking,
hydrogen consumption is significantly
lower than hydrocracking, and no lowvalue residual products remain to be pro-

cessed further or sold into the high-sulfur
fuel oil (HSFO) market.
The proprietary upgrading process
was designed with a focus on three primary principles. These include:
1. Feeding the process an ISO
8217-compliant heavy marine
HSFO and removing the
sulfur and other environmental
contaminants, while maintaining
the energy density and other
bulk properties of residual
fuel oils for which most ships'
main engines are designed.
2. Addressing the overabundance
of HSFO and high-sulfur residual
components in the market by
developing a straightforward,
robust process to produce 0.5
wt% sulfur ISO 8217 residual
fuel oil with a minimal yield of
byproducts. Using 1 mass unit
of HSFO feed, the proprietary
upgrading process produces
approximately 0.96 mass units of
ISO 8217-compliant VLSFO,
with the balance being about
0.025 mass units of sulfur
and minor amounts of wild
naphtha and light ends
(less than 0.015 mass units).
3. Positioning the process to be
installed on a compact footprint
within a refinery or near/adjacent
to points of aggregation (i.e.,
fuel oil terminals). A preferred
location will have excess
hydrogen or pipeline hydrogen
available and will utilize existing
systems (e.g., tanks and utilities)
of the current logistics flow in
the existing HSFO supply chain.
The addition of the proprietary
upgrading process unit should
Hydrocarbon Processing | APRIL 2021

Hydrocarbon Processing - April 2021

Table of Contents for the Digital Edition of Hydrocarbon Processing - April 2021