Hydrocarbon Processing - October 2021 - GP-19

SPECIAL FOCUS: LNG TECHNOLOGY
including Curtis Island LNG, Papua New
Guinea LNG, Wheatstone LNG (with an
LM6000PF turbine) and, recently, the
Arctic LNG 2 project, which is still under
construction, with an LM9000 turbine.
For offshore applications, the
PGT25+G4 gas turbine from Baker
Hughes/General Electric's LM2500 family
has been applied at the Coral South FLNG
(FIG. 8), which operates on a dual mixedrefrigerant
process. The PGT25+G4 has
been also applied at Petronas' PFLNG
Satu, which operates on an AP-N process,
as well as several other FLNG facilities,
such as Golar FLNG vessels and the
Gorskaya FLNG. An LM6000PF, another
aeroderivative gas turbine, has been applied
at Petronas' Rotan FLNG to deliver
roughly 30% more output power compared
to a PGT25+G4 gas turbine.
Shaftline power enhancement.
Aeroderivative gas turbines are more
sensitive to daily and/or seasonal fluctuations
in air temperature than heavy-duty
gas turbines. To compensate for periods
of high ambient temperature, inlet air
chilling can be used to mitigate the slight
adverse impact on output power. When
the power shortage is high at hot ambient,
a helper motor is applied to supplement
the power shortage from a heavyduty
gas turbine.
Waste heat recovery unit. A waste heat
recovery unit (WHRU) can be fitted at
the exhaust stack of the gas turbines for
the main refrigerant compressors when
the power margin between gas turbine
output power vs. driven compressors absorbed
power allows. Roughly speaking,
adding a WHRU could lead to an approximate
0.4% drop in output power of the
gas turbine, depending on the operating
conditions and the design of the WHRU.
Maintenance considerations. Maintenance
intervention is more frequent but
less time-intensive for aeroderivative gas
turbines compared to that required for
heavy-duty gas turbines. Dual-shaft gas
turbines, in general, are much easier to
maintain. General Electric's Frame-5 is an
example of a heavy-duty gas turbine with
a dual-shaft arrangement.
A new generation of large, dual-shaft,
heavy-duty gas turbines has been initiated
with the introduction of the MHPS H-100
for use in LNG plants. This turbine offers
shorter shutdowns for maintenance. In
addition, the dual-shaft design eliminates
the need for a large starter motor.
Novelty management. The adoption
of new, unproven technologies should be
avoided wherever possible. However, the
increase in LNG train size and the interest
in scale as a way of reducing CAPEX
sometimes leads to gas turbines being
selected while still in the development
phase, and with risks that are still under assessment
by the gas turbine manufacturer.
An example of a new development is
Baker Hughes/General Electric's LM9000
aeroderivative gas turbine, which is based
on the GE-90 aircraft engine. As a twoshaft
machine with ISO shaft power reaching
approximately 70 MW, it is capable
of revolutionizing upcoming LNG plant
designs. The adoption of the LM9000 on
the Arctic LNG 2 project implied a qualification
program and additional studies,
simulations and tests during the engineering
phase of the project.
A " technology qualification " process
consists of an in-depth analysis of the
design, development and integration of
new or borrowed technologies to identify
risks and implement mitigations. The
process follows a structured procedure to
identify and screen novelty designs within
a new product and assess the readiness
level of each novelty. This qualification
program is normally led by the owneroperator
and is based on the owner's internal
processes and field experience.
A first step in such a qualification process
is the identification, component by
component, of all novelties within the
gas turbine design. Examples include a
new material or coating, a new production
process, new operating conditions
or a combination of these items. Once
identified, and after technical validation
is performed, a risk mitigation plan must
be established. This will often result in
demanding tests such as a full-speed,
full-load string test or an endurance test,
which must be taken into account in the
overall schedule of the project.
Takeaway. Turbomachinery selection
for LNG plants encompasses several
steps of screening to reach the optimum
driver and compressor configuration
choice. This broad choice is impacted by
the unique aspects for each LNG plant,
including the production capacity, train
size, CO2 emissions and other environmental
targets, site location (particularly
when not onshore), site ambient conditions
and variations, demand for utilities,
availability of electrical power from the
grid and the need for waste heat recovery.
A successful selection process is a
joint effort between the owner and a
specialized LNG engineering contractor.
The optimum selection of driver and
compressor configuration is achieved
through a comprehensive assessment by
an interdisciplinary team of engineers
and estimators. GP
ACKNOWLEDGMENT
The authors of this paper thank the TechnipEnergies
LNG product line and the Paris Engineering and
Process Department management for sponsoring
this paper for the GPA Europe Annual Meeting and
Technical Meeting in 2020.
NOTES
a
b
This article was originally presented at GPA Europe's
Annual Meeting and Technical Meeting in 2020.
X-axis and y-axis values are not shown due to copyright
reasons.
MOUNIR MOSSOLLY is Technical
Advisor and Lead Engineer at
TechnipEnergies and the Honorary
Chairman of IMechE Groupe France.
He is a Chartered Engineer and a
Certified Manager of Quality and
Organizational Excellence by ASQ.
In the context of his expertise in turbomachinery,
Dr. Mossolly has been involved with some of the
largest, most complex and most challenging LNG
projects worldwide, such as the pioneering Prelude
FLNG, Yamal LNG and Coral FLNG. At present, he is
working on the Qatar North Field Expansion EPC-1
LNG project. Dr. Mossolly holds a PhD in project and
program management and an MS degree in
mechanical engineering.
CELINE BELBOL is Head of the
Rotating Equipment Department
at TechnipEnergies Paris, and has
more than 17 yr of experience in the
energy industry. She started her
career with Technip as a Rotating
Engineer and progressed to the
position of Team Leader Engineer before being
appointed Head of the Rotating Equipment Department.
She gained her technical experience through
involvement in various onshore and offshore oil and gas
projects and through team management of complex
mega-LNG projects, such as Yamal LNG and Coral FLNG.
VINCENT TIRILLY is a Principal
Process Engineer in the Process
and Technologies Division of
TechnipEnergies' LNG Department.
He is also a Member of the Expert
Network from TechnipEnergies
with more than 25 yr of experience
in onshore and offshore LNG projects. Mr. Tirilly
has been involved in all stages of LNG project
development, from early conceptual stage to FEED
and EPC, including for the Coral FLNG and Qatar's
North Field East and North Field South projects.
Gas Processing & LNG | SEPTEMBER/OCTOBER 2021 19
Hydrocarbon Processing - October 2021

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