By Billy Thinnes
DALLAS -- Pemex hired KBC Advanced Technologies to help it
improve the profitability and reliability of its national refining
system. A major focus for this project was an upgrade to the
linear program (LP) model for Pemex's refining system, and the quest to
improve production planning work processes.
The LP upgrade project involved upgrading the process unit
LP representations in all six Pemex refineries, which
constitute the backbone of the company's 1.3-MMbpd refining system. It took place from
December 2010 to July 2012.
Pemex's Ihali Crespo led off a presentation at the AFPM
Q&A and Technology Forum by confirming the
six refineries that received attention: Madero, Salina Cruz,
Cadereyta, Tula, Minatitlán and Samanca.
Michael Tucker, one of the KBC leads on the project, followed Ms. Crespo and
noted that each phase at each refinery had an onsite review of LP
system parameters, structures, stream routings, process limits
and blending options. Process unit table updates were mainly
based on KBC's PetroSIM flowsheet base-case simulation.
Mr. Tucker and his team also debugged the model using LP
system validation diagnostics, meaning that they tested all
modeled features including crude oil options, product options
and cutpoints. When all was said and done, the modeling
indicated a minimal deviation on gasoline, diesel and fuel oil
within the system.
Ms. Crespo noted that the objective of the project was to maximize profit.
However, she readily acknowledged the constraints facing the
team, including capacities, product qualities and environmental
regulations. She also shared the product demand and
distribution landscape for Pemex within the LP: demand is
associated with 77 markets, passing through 85 transference
nodes that are connected by barge, pipeline, truck and rail
modes of transport. Ms. Crespo also informed audience members
that there are six gasoline types in Mexico.
Mr. Tucker then explained that one of KBC's objectives was
to tune up the process unit area. By utilizing the PetroSIM
system, his team was able to offer a new crude assay yield;
updated crude unit cutpoints; upgraded property index formulas;
and upgraded mass balances, blending options and stream
Benefits and lessons learned. Mr. Tucker
said improvements were made to the accuracy of the model by
tuning up the yields and adding more swing cuts to the crude
tower. This was a significant change, he said, as the team
eventually added five swing cuts to the model. Other upgrade
activities of note were corrected steam routings, mass balance
equalization and other error reductions in decision-making.
According to Mr. Tucker, the project execution efficiency
benefited from previous KBC/Pemex projects and relationships.
"We've been working together on various configuration projects for over 10 years," Mr.
He noted that there were some interesting problems with the
data. "We had to go through a lot of reconciliation to get
these simulators calibrated," Mr. Tucker said.
Mr. Tucker summarized his presentation by saying that the
Pemex global LP is an ideal application for the optimization of
a large domestic crude supply, refining and product distribution
system. It now allows for optimized crude supply and
distribution, inter-refinery transfers, product
distribution and imports/exports.
To clarify, Petro-SIM is KBC's refinery-wide process
simulation software, complete with multiple process unit
simulation models for each location. Petro-SIM allows process
engineers to model all of their refinery assets, enabling them
to optimize, analyze and evaluate complex refinery interactions. Petro-SIM can
be used to determine the impact of different feedstocks and operating targets,
monitor process performance, conduct investment studies or
update an LP model.
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