Hydrocarbon Processing - August 2021 - 43

Process Optimization
By this operating condition, the VR
will have sulfur at a 0.7 wt% maximum,
and the viscosity will be around 4,000
cSt-5,000 cSt at 50°C. Blending lowsulfur
ARD distillate and TGO from the
VR unit (sulfur limit of 0.15 wt%), the required
VLSFO production was achieved.
MAA refinery
issues while handling
imported materials. To adhere
to VLSFO bunker fuel requirements, a
cargo was imported with 0.46 wt% sulfur
in December 2019 into the MAA
refinery's bunker tanks. Prior to import,
both tanks were cleaned, and the associated
system was flushed thoroughly using
500-ppm gasoil. Upon completion of
import, both the tanks were certified as
per IMO specifications.
During this period, the MAB refinery
produced a batch of VLSFO as per Option
4; therefore, a vessel was arranged
to the MAA refinery. Upon loading, the
ship's composite sample at the MAB refinery
port met all specifications; however,
prior to discharge, there were concerns
on the compatibility of the remaining
BFO material at the MAA refinery with
the newly imported material. After quality
control clearance, the imported BFO
was discharged into the bunker tanks at
the end of January 2020. Upon receipt,
the fuel met the BFO IMO specifications
but tank sulfur result samples were
marginally at the specification limit
(0.5 wt%). However, the batch did not
have the sufficient sulfur limit margin to
be supplied to vessels and with no facility
for correcting the product, it was decided
to dispose of (export) the product.
Upon arranging a vessel to load the product,
the tank samples (TABLE 10) showed
that the sulfur content was 0.44 wt% and
0.46 wt%, respectively. However, samples
taken over the next several weeks showed
inconsistencies in mixtures. In addition,
the total sediment results after mixing
had presented inconsistencies. This solidified
the conclusion that asphaltene
(having the highest sulfur proportion to
the mixture) miscible in the mixture may
had precipitated due to compatibility issues
and affected the sulfur results.
From these results, it can be inferred
that it is imperative that all receipts of this
grade fuel oil should have a maximum
of 0.47 wt% (95% confidence level) and
shown to be tested for compatibility before
blending/mixing. This clarifies the
TABLE 9. BFO results of Option 5
Parameter
Aluminum and silicon, mg/kg
Ash, % mass
CCAI
Density at 15°C, kg/l
Flash point (PMCC), °C
H2S, mg/kg
Phosphorus, mg/kg
Pour point, °C
Relative density at 60°F
Sulfur (total), % mass
Total sediment potential, % mass
Vanadium, mg/kg
Viscosity, kinematic at 50°C, cSt
TABLE 10. MAA refinery bunker tank results
Parameter
Aluminum and silicon, mg/kg
Ash, % mass
Density at 15°C, kg/l
Flash point (PMCC), °C
H2S, mg/kg
Relative density at 60°F
Total sulfur, % mass
Total sediment potential, % mass
Vanadium, mg/kg
Kinematic viscosity at 50°C, cSt
CCAI
challenges that were met and the efforts
exerted to meet IMO requirements.
Takeaway. With the new IMO 2020
low-sulfur regulation, bunker production
must use low-sulfur blend components to
be compliant. Sludge issues can be avoided
by calculating the fuel's compatibility
and stability. The asphaltene content and
aromaticity of fuel oil are critical to its fitness
for use.
KNPC achieved the most economically
feasible way of producing VLSFO by using
distillate, VR and TGO streams originating
from its latest clean fuels project
units. This VLSFO met the IMO 0.5 BFO
specifications with a minimum viscosity
of 250 cSt, and was a stable product due
to the low asphaltene content of the VR.
These accomplishments enable KNPC
to be in position to adhere to the IMO
Result
0.1
0.02
800.1
0.9353
114
0.3
-3
0.9358
0.45
0.1
10
276
VLSFO 1
24.88
0.03
VLSFO 2
43.8
0.03
0.937
104
0.5
0.9376
0.44
0.04
3.8
345
800
0.9354
100
0.5
0.936
0.46
0.04
3.7
348
798
mandatory requirements of VLSFO IMO
BFO, with financial benefits. In addition,
these accomplishments will help the
MAA refinery to modify its production
slots based on the economics and market
demands.
ACKNOWLEDGMENTS
The authors would like to thank Rathina Sabapathi
Kanagasabai, Kishor Datta Purkayastha and Mayank
Garg for their help in preparing this article.
MOHAMMAD B. MATAR is a Chemical Engineer and
the Team Leader for Operational Planning at KNPC,
with experience in refinery operations, planning
and process engineering.
ALI AL MANE is a Chemical Engineer with more than
15 yr of experience. He works in operational planning
and has played a significant part in the MAA CFP
commissioning.
MUTHUSAMY RAJENDRAN is a Chemical Engineer
with 30 yr of experience in planning at KNPC and
has worked in various fields of planning/operations
and commissioning.
Hydrocarbon Processing | AUGUST 2021 43
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