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HYDROCARBON
ENGINEERING
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solving, and the virtual with the reality, is vital. It is for this
reason that the future value of process simulation will be based
on three fundamental pillars: the science that underpins it;
people’s ability to use it; and the use of digital technologies to
increase its value.
The science
The focus of getting the science right is to deliver rigorous
engineering accuracy and fidelity so that users never have to
compromise on result quality. However, getting this right means
securing a common language, in the form of thermodynamics
and physical properties for a high-fidelity digital twin. They are
the most important building blocks for a data-meets-simulation
approach to engineering design and optimisation.
Natively combining physical property modelling capabilities
with advanced electrolyte thermodynamics allows simulation
to accurately support and validate recommendations. This
allows for a wider range of effects in different and new
operating envelopes.
For example, engineers now have readily available stream
properties for managing corrosion and fouling. This is possible
by a sitewide flowsheet which natively incorporates fluid
characterisation/PVT models fromMultiflash, and the
electrolyte chemistry modelling capabilities from the
OLI Engine. It includes absolute, as well as pseudo stream
components, covering ionic and non-ionic systems. The tool
delivers model fidelity and engineering efficiency for holistic
measurement, prediction, and mitigation of corrosion, scaling,
and fouling in aqueous environments.
Case study 1
A gasoil hydrocracker producing light and heavy naphtha,
kerosene, and diesel had effluent that included H
2
S and
ammonia concentrations of 3.95 and 0.46 mass percent. Cooling,
washing, and stripping the effluent is desirable to achieve a
product with less than 15 ppmwt of H
2
S. The wash water flow is
set at 93 tph in order to control the precipitation of solid
NH
4
HS. Too little washing will cause corrosion due to the
presence of NH
4
HS. Excessive washing will cause a financial
penalty, but sour water processing may also limit the effects.
To save wash water, two possible changes in the operation
were investigated using Petro-SIM
®
, powered by the OLI Engine,
to prove the effect of the amount and quality of the wash
water in corrosion control:
n
Reduce the flow rate of wash water by 20%.
n
Recycle sour water to make up 50% of wash water.
The predisposition of NH
4
HS and NH
4
Cl to precipitate as a
solid was calculated and reported as scale tendency. The
interpretation of scaling tendency, for the purpose of corrosion
analysis, is to avoid a scale tendency of greater than 1. In each
case, the scaling tendencies of NH
4
HS in the main suspect
streams were 0.0009 to 0.0013 and 0.0028, respectively. The
advanced analytics indicated a significant increase in the scaling
tendency but was significantly below where scaling is expected
to form.
The use of Petro-SIMwas able to confirm the operating
integrity window for the gasoil hydrocracker. This allowed for
planning and executing more robust operating strategies.
The people
Unfortunately, science by itself does not translate directly into
results. Greater empowerment of people is necessary to
deliver better outcomes. However, too often technology
usability barriers and day-to-day tasks make embracing the
science a challenge. Technology usability for different types of
users is critical. There must be a strong focus on ease of use,
making the complex simple, and allowing multiple disciplines
to look at the same model, input their own data, and interpret
the results together.
Engineers live and breathe spreadsheets. After all, they are
the linchpin of bills of material, engineering formulas and
calculations, as well as product costs. But the spreadsheets
themselves need engineer manipulation to be effective, which
takes time.
Deep and highly functional integration between
spreadsheet and simulator is a requirement.
User-driven-methods are necessary to get the right information
into and out of the process simulator. New dataset analysis
utility tools can also help users better understand and manage
their data in a process model, thereby driving increased
engineer productivity.
On the topic of human productivity, even the smallest
repetitive tasks are a major waste of time and cost when
engineering at scale. However, workflow-enabled simulation
technology enables faster engineering within a set of
acceptable boundaries and standards. In-built simulation
workflow engines can help manage risk and enhance speed and
efficiency through programmable execution of repetitive
engineering tasks and pre-designed templates.
Case study 2
Baker Hughes partnered with KBC to develop a highly intuitive
continuous process management (CPM)
solution for mitigating refinery preheat
train fouling.
1
Preheat trains play a
critical role in reducing energy
consumption. However, they often
experience performance degradation,
thereby impairing their heat exchange
capabilities. Although fouling severity
varies from one refinery to another, a
typical 100 000 bpd facility can lose
more than US$5 million/yr as a result
of this issue.
Before CPM, refinery engineers
typically predict fouling using
Figure 1.
Cleaned the wrong bundle too late (left). Right bundle cleaned at
the right time (right).