Hydrocarbon Processing - June 2022 - GP-24

LNG
TABLE 1. Comparison of retrofit and new-build CO2
LNG liquefaction plant
Gas turbine arrangement
Natural gas feed vs. base case, %
Net-in-tank production vs base case, %
H2 produced, MMft3
d
Liquefaction specific power vs base case, %
Auto-consumption vs. base case, %
Total CO2 captured, tph
% emissions reduction vs. base case
The " full H2
gas to the H2
" case sends all the flash
production facility, generating
a fuel stream of predominantly H2
(with N2
or steam as diluents). Although
some industrial gas turbines are capable of
handling such a fuel stream, these turbines
may require a conversion of the combustion
system and fuel delivery system modifications
to do so.
In both options, additional gas turbine
generators are required to supplement the
existing electric power. These can be located
at the H2
production facility.
New-build case. The new-build case examines
a potential new LNG liquefaction
facility. This hypothetical plant utilizes
three aeroderivative gas turbines in combined-cycle
for power generation, as well
as one or more small gas turbine generators
to supplement the available power. Electric
motors driving the liquefaction compressors
use most of the generated power. The
remaining power is used for the balance of
plant. Liquefaction compressor power has
been fixed at the value used for the base
case for ease of comparison.
For all three cases, the following additional
technology selections were made:
* High-conversion POX process
for H2
production
* Air separation unit (ASU) to provide
low-purity gaseous oxygen for POX
* AGRU designed to recover CO2
and compress to pipeline pressure
* Amine unit integrated into the H2
production facility to separate
CO2
from the H2
in TABLE 1.
Takeaways. In the retrofit cases, the
higher flash gas demand improved the
liquefaction specific power-the liquefac24
MAY/JUNE 2022 | GasProcessingNews.com
product.
The results for each case are shown
emissions to generic baseload
Retrofit: Partial H2
Industrial GT,
simple-cycle
100.7%
100.4%
18
99.6%
103.3%
75.4
32.6%
Retrofit: Full H2
Industrial GT,
simple-cycle
107.5%
102.4%
299
98%
150.7%
297.6
96.6%
New-build
Aero GT,
combined-cycle
99.1%
99.5%
176
100.5%
96.8%
197.8
98%
tion compression power required to produce
1 metric t of LNG-allowing more
LNG to be produced for the liquefaction
power. The partial H2
case achieved 0.4%
higher production, whereas the full H2
case achieved 2.4% higher production.
For the new-build case, a more efficient
gas turbine selection reduced the flash
gas requirement and slightly reduced the
LNG production.
However, the new-build case's efficiency
provides significantly better autoconsumption-the
percentage of feed
consumed as fuel-than the retrofit cases.
The new-build case also requires a significantly
smaller H2
significantly lower for the new-build case
compared to the full H2
reduces the required size of the CO2
3
4
cant changes to the gas turbines to accommodate
high-H2
fuels. Both cases
show how the pre-combustion capture
technologya
NOTES
a Air Products' AP-Blue™ LNG
b
Air Products' AP-C3MR™
LITERATURE CITED
1
Mallapragada, D. S., E. Reyes-Bastida, F. Roberto,
E. M. McElroy, D. Veskovic and I. Laurenzi, " Life
cycle greenhouse gas emissions and freshwater consumption
of liquefied Marcellus shale gas used for
international power generation, " Journal of Cleaner
Production, 2018.
2
Ott, C. M., J. D. Bukowski, R. Shnitser and J. Dunn,
" Efficiency, low CAPEX nitrogen removal for natural
gas liquefaction, " Gastech 2021, Dubai, September
21, 2021.
Saunderson, R. P., " End-flash is totally cool, "
Hydrocarbon Engineering, May 2021.
Folger, P., " Carbon capture technology assessment:
In brief, " U.S. Congressional Research Service,
R43300, November 5, 2013.
5
Dewing, R., V. White and J. Hicks, " Hydrogen plants
with CO2
capture: Retro-fit options and practical
considerations, " 15th International Conference on
Greenhouse Gas Control Technologies (GHGT-15)
Abu Dhabi, UAE, October 5-8, 2020.
production facility for a
similar liquefaction plant to achieve 97%
emissions reduction. The overall CO2
generated during H2
production is also
retrofit, which
compression
system.
Both retrofit and new-build cases are
capable of a high degree of overall CO2
capture by capturing CO2
generated in the H2
production
facility.
The partial H2
from the natural
gas feed and by pre-combustion capture
of the CO2
retrofit case achieved
a CO2 emissions reduction of 32.6%, an
improvement over capturing CO2 from
the AGRU alone. Due to the modest H2
requirement for this case, one H2
plant
can serve multiple LNG trains. The primary
advantage of this case is its compatibility
with existing gas turbines with only
minor upgrades.
The full H2
cases achieved CO2
retrofit and new-build
emissions reductions
of 96.6% and 98%, respectively. These
cases show how existing and new plants
may achieve a high degree of emissions
reduction, though both require signifiMARK
ROBERTS joined Air Products in 1996 and has
more than 30 yr of experience developing cryogenic
cycles for gas separation and liquefaction in the
air separation, hydrocarbon processing and LNG
industries. He has more than 40 U.S. and international
patents issued in his name, including the patents for
the AP-X™ liquefaction process used for the six megatrains
in Qatar, the patent for the AP-N™ liquefaction
process deployed in the first offshore project, Petronas
FLNG Satu, and the patents for the AP-DMR™ dualmixed
refrigerant liquefaction process used on the
Coral South FLNG vessel under construction.
DAVE GRAHAM is a Research Engineer at Air Products
and Chemicals. He has worked in the areas of H2
production, air separation, LNG and carbon capture
during his 22-yr career. Dr. Graham earned a BSE
degree from the University of Michigan, and MS
and PhD degrees from the University of Illinois.
DEJAN VESKOVIC joined Air Products in 2011 as
part of the Air Products HyCO business, supporting
process safety and plant operations. He now works
as a Principal Process Engineer in the LNG Process
group, where he has designed and developed LNG
plants with a range of liquefaction technologies, as
well as supported the startup and performance testing
of those plants. He received his BS and MS degrees
in chemical engineering from Pennsylvania State
University and Villanova University, respectively.
JEREMY D. BEARD is a Lead Machinery Engineer in the
Process Gases Group at Air Products and Chemicals
Inc., supporting both the development and execution
of new projects related to the production of blue
H2
through carbon capture, utilization and storage.
Mr. Beard has also provided machinery support to
other groups within Air Products in the development
of projects and process technology in LNG, syngas
and other products. He received his BS degree in
mechanical engineering from Louisiana State University.
provides a pathway to eliminating
the carbon footprint of natural
gas liquefaction. GP
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