Hydrocarbon Processing - August 2021 - GP-18

SPECIAL FOCUS: SMALL-SCALE LNG
TABLE 1. Case study examples for small-scale pressurized and atmospheric solutions
Peak
Case
1
2
3
Nominal power
generation
25 MW
100 MW
150 MW
consumption
27.8 MW
111.1 MW
166.7 MW
LNG required,
MMtpy
0.034
0.135
0.203
Average LNG
requirement, Nm3/d
145,160
580,640
870,960
*VI bullets = Vacuum-insulated bullets; FC S/C = Full containment, steel/concrete tanks
delivery time to enable the commencement
of commercial operations and an
optimized return on investment.
FIG. 2. In addition to supplying fuel directly to a power station, LNG can be supplied to
other customers, such as other LNG satellite stations, LNG fueling stations, other mini-power
generation sites or marine operations.
The delivery times of these project
vary depending on several factors, including
delivery times for the power units.
However, when the project requires larger-size
storage tanks, then the tank construction
dominates the critical path.
The storage capacity is based on a
FIG. 3. ISO container on trailer used to store
LNG at mini-scale power facilities.
distribution, local industrial consumers
and vehicle refueling stations.
The high-level concept for SSLNGto-power
remains virtually the same for
varying power generation levels required;
however, when optimizing the concept
for a particular site or project, all applicable
parameters must be considered.
Case studies for SSLNG-to-power.
A number of case studies have been
developed for varying levels of power
generation of 25 MW, 100 MW and
150 MW. Power generation is based on
simple-cycle engines with a thermal efficiency
of 48%, using a typical LNG
heating value, with one LNG cargo delivery
every 4 wk and a delivery power of
8,000 hr/yr. TABLE 1 compares examples
for the small-scale pressurized and atmospheric
solutions.
18 JULY/AUGUST 2021 | GasProcessingNews.com
4-wk delivery term, but this will be subject
to the availability of LNG in the specific
market and the size of the LNG carrier
available. Additional small LNGCs
are coming into operation as the demand
for smaller cargoes increases, which will
provide a benefit to small-scale terminals.
Another option may be to receive a portion
of a cargo from a larger LNGC.
Modular design concept. Depending
on the individual project, the construction
concept can be optimized based on
location and the type of equipment to be
installed. Given the nature of the overall
SSLNG-to-power concept, it can be
assumed that the location is more than
likely to be remote, with potentially low
levels of infrastructure and construction
labor availability.
The remote location will benefit from
a minimum of in-situ construction and
from equipment and plant sections being
provided as modularized units. At least
partial adherence to these targets will reduce
construction costs by maximizing
prefabrication. The modularized design
approach brings clear advantages in plant
expandability while fast-tracking project
Mini-scale power production. At
< 50 MW, these small-sized power
plants usually serve the power demand
of a smaller island without significant
industrial power demand. The LNG
can be transported via ISO containers
on LNG trucks (FIG. 3) or by rail (often
referred to as a " virtual pipeline " ),
with each holding approximately 43 m3
of product. They can be lifted from the
trailer assembly or left in-situ on the
trailer for distribution in the plant.
Although the
storage
is modular,
and
these ISO containers provide an option
for storage solutions up to 500 m3
produce low levels of power generation.
A significant advantage of using ISO
containers is that the facility does not
need to be in a marine location, but can
be situated inland at more convenient
sites. At the power plant, the LNG is
stored in small, pressurized vessels.
Small-scale power production. As
power generation requirements increase
up to 50 MW, so does the size of the storage.
The storage concept changes to utilize
vacuum-insulated bullets, each with
a typical capacity of 1,000 m3
Economic designs up to 10,000 m3
(FIG. 4).
can be
achieved, with the remainder of the plant
being fully modularized, which means
that the overall schedule can be reduced
to approximately 16 mos-18 mos.
This concept does not incorporate a
boil-off gas handling system; instead, the
LNG is allowed to warm up within the
storage, as the system can operate with
zero sendout for up to 2 mos without any
venting requirements
Star-fin ambient air vaporizers are a simple
vaporization solution in this concept.
They are a suitable technology for most climates;
however, some additional heating
may be required for colder climates.
Delivery max.
prefabrication, mos
18
24
24
Delivery
stickbuilt, mos
20
26
26
Storage
capacity
Tank
concept*
6,000 m3 VI bullets
25,000 m3 FC S/C
38,000 m3 FC S/C

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Hydrocarbon Processing - August 2021

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