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Technologies for hydrogen liquefactionDavid Berstad, SINTEF Energi AS
Gasskonferansen, Trondheim, 11. april
Presentation outline
• Properties of hydrogen
• Brief history of hydrogen liquefaction
•Hydrogen liquefiers, current use and capacities
•Description of state-of-the-art liquefaction technology
•Outlook – potential for short- and long-term
improvements for hydrogen liquefaction processes
2
Hydrogen (H2) properties
• Molar mass: 2.016 kg/kmol
• Normal boiling point: ≈ 20.3 K (≈ -253 °C)
• Critial pressure: ≈ 13 bar
• Critical temperature: ≈ 33 K (≈ -240 °C)
• Normal liquid density: ≈ 71 kg/m3
• Lower heating value: 120 MJ/kg (33.3 kWh/kg)
• Higher heating value: 142 MJ/kg (39.4 kWh/kg)
3
Some liquid-hydrogen-related historic events
• 1898: First successful liquefaction by J. Dewar (UK)
• 1952: 0.6 t/d liquefier built (NBS-AEC Cryogenic Engineering Laboratory,
Boulder, Colorado)
• Mid/late 1950s: Liquid hydrogen demand for space rocket propulsion
• 0.8 t/d + 3.4 t/d + 27 t/d (Built by Air Products in West Palm Beach, Florida)
• 1987: Europe's largest hydrogen liquefaction plant built
• 10 t/d (Build by Air Liquide in Waziers, France)
• Liquid hydrogen needed for development of the Ariane 5 space launch vehicle
4
Current applications for liquid hydrogen
• Aerospace industry
• Chemical industries
• Electronic/semiconductor industry
• Health care industries
• Metallurgical industries
• Fuel cell manufacturers
• Glass production
• Food and beverage industry5
LH2
LH2
Purpose of liquefaction
• Enabling high-density storage and transport at low pressure
• Transport and storage economics analogous to LNG vs. CNG
7
1
10
100
1000
0 50 100 150 200 250 300 350
Den
sity
rat
io:
Lqiu
id a
t 1
atm
/ C
om
pre
sse
d g
as
Pressure of compressed gas [bar]
Hydrogen
Methane
Importance of high hydrogen liquefier efficiency
Ratio between liquefaction power (electric) and energy
content (heating value) of the liquefied gas
8
0%
5%
10%
15%
20%
25%
30%
35%
25% 30% 35% 40% 45% 50% 55% 60%
Liq
uef
acti
on
po
wer
/ E
ner
gy c
on
ten
t
Exergy efficiency of liquefaction process
Hydrogen, LHV
Hydrogen, HHV
Methane, LHV
Methane, HHV
State of the art (5–10 ton per day)
Snøhvit LNG (15 000 ton per day)
Large potential for improving hydrogen liquefier efficiency by
scaling up train capacity!
Methane
Current liquid hydrogen storage capacity
9
Image source:• https://www.nasa.gov/content/liquid-hydrogen-
the-fuel-of-choice-for-space-exploration• Kawasaki Heavy Industries
≈ 12 m≈ 20 m
NASA, USA3 800 m3
270 t
JAXA, Japan540 m3
38 t
LH2 truck< 50 m3
< 3.5 t
Large-scale liquid hydrogen storage
10
≈ 45 m
≈ 12 m≈ 20 m
NASA, USA3 800 m3
270 t
JAXA, Japan540 m3
38 t
40 000 m3
2 800 t50 000 m3
3 500 t
LH2 truck< 50 m3
< 3.5 t
Existing
Image source: Kawasaki Heavy Industries
Hydrogen liquefier feed and product conditions
• Hydrogen feed pressure: typically 15–20 bar (critical pressure is
approximately 13 bar)
• Hydrogen purity requirement: Generally 10–100 ppm, depending on
impurity composition
• Internal adsorbers at low temperature in the liquefier reduces the
impurities concentration to < 1 ppm before final liquefaction stages
• Final liquid hydrogen state:
• Typically saturated or subcooled liquid at 1.2–1.5 bar
• Para-hydrogen content > 95 %11
State of the art for hydrogen liquefaction
• Current "large-scale" plants
• Capacity of typically 5–15 ton per day
• Hydrogen Claude cycles using liquid nitrogen for precooling
• Typically 10–12 kWh/kg specific liquefaction power
• Smaller plants
• Capacity typically below 2–3 ton per day
• Helium Brayton cycles with liquid nitrogen precooling gives the best overall
economy
• Lower capacities can also be delivered, down to approximately 0.15 ton per day
• Small capacities are more sensitive to CAPEX and less to OPEX12
13
H2 fe
ed
-193°C
-180°C
30°C
LN2
-242°C
-243°C –
-251°C
-252°C
20 bar
1.2–1.5 bar
20–25
bar
3–5 bar
1.2–
1.3 bar
State of the art for hydrogen liquefaction
• Hydrogen Claude cycle
• Liquid nitrogen pre-cooling to ≈ 80 K
• Hydrogen purification in adsorbers after
LN2 pre-cooling
• Adiabatic ortho-para conversion after
LN2 pre-cooling
• Further continuous ortho-para
conversion internally in heat exchangers
• Final liquefaction by expansion through
an ejector, also recompressing boiloff
gas from storage
Hydrogen Claude refrigeration cycle
LN2 precooling cycle
Hyd
rogen
14
H2 fe
ed
-193°C
-180°C
30°C
LN2
-242°C
-243°C –
-251°C
-252°C
20 bar
1.2–1.5 bar
20–25
bar
3–5 bar
1.2–
1.3 bar
State of the art for hydrogen liquefaction
Oil-free hydrogen piston compressors
• 2-stage low-pressure compressor
• 2-stage high-pressure compressor
Plate-fin heat exchangers filled with catalyst
grains on the hydrogen feed side for ortho-
para conversion
Open liquid nitrogen pre-cooling process
• Supplied from adjacent air separation
unit or other source
Capacity control: Smooth load control
between roughly 40 % and 100 % load
Hydrogen Claude refrigeration cycle
LN2 precooling cycle
Hyd
rogen
15
H2 fe
ed
-193°C
-180°C
30°C
LN2
-242°C
-243°C –
-251°C
-252°C
20 bar
1.2–1.5 bar
20–25
bar
3–5 bar
1.2–
1.3 bar
State of the art for hydrogen liquefaction
Cryogenic expanders
• Radial hydrogen turboexpanders
• Oil or gas bearings (or magnetic)
• Dynamic gas bearings are most
reliable and the current frontier.
Installed in all recent liquefiers in
Japan
• Typically 10–50 kW, up to > 85%
isentropic efficiency
• Oil or gas brakes to dissipate shaft
power
Hydrogen Claude refrigeration cycle
LN2 precooling cycle
Hyd
rogen
Courtesy of Linde Kryotechnik AG.S. Bischoff, L. Decker. First operating results of a dynamic gas bearingTurbine in an industrial hydrogen liquefier. AIP Conference Proceedings 1218, 887 (2010)
• High-efficiency hydrocarbon-based mixed refrigerant pre-cooling processes
• PRICO-type, Kleemenko-type, or cascade-type processes are possible
• Higher degree of process integration Lower losses in heat exchangers
• Larger and more efficient compression and expansion machinery
• Possibility of power recovery from cryogenic expanders instead of dissipating
the shaft power with brakes
• Lower relative boil-off rate from liquid hydrogen storage
• Long-term: Possibly new refrigerant mixtures, e.g. He/Ne or H2/Ne to enable
the use of turbocompressors instead of piston compressors16
Scaling up liquefier train capacity enables…
0
1
2
3
4
-260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160
Re
lati
ve e
xerg
y lo
ss
kW e
xerg
y /
kW h
eat
tra
nsf
err
ed
]
Hot side temperature {°C]
ΔT between hot and cold side [°C]
ΔT 5 °C
ΔT 4 °C
ΔT 3 °C
ΔT 2 °C
ΔT 1 °C
Very tigh heat integration needed to curb thermodynamic losses
17
QΔT
Hot side
Cold side
18
Composite Curves for a block with 100 ton hydrogen per day capacity
Very tigh heat integration needed to curb thermodynamic losses
020406080
100120140160180200220240260280300
0 5 10 15 20 25 30 35 40 45
Tem
per
atu
re [
K]
Duty [MW]
19
Composite Curves for a block with 100 ton hydrogen per day capacity
Very tigh heat integration needed to curb thermodynamic losses
0
1
2
3
4
5
6
7
8
9
020406080
100120140160180200220240260280300
0 5 10 15 20 25 30 35 40 45
Tem
per
atu
re d
iffe
ren
ce [
K]
Tem
per
atu
re [
K]
Duty [MW]
Targeted liquefier efficiency improvement
Up to 50 % reduction of power requirement has been identified by several projects1,2
20
10%
15%
20%
25%
30%
35%
25% 30% 35% 40% 45% 50% 55% 60%
Liq
uef
acti
on
po
wer
/ E
ner
gy c
on
ten
t
Exergy efficiency of liquefaction process
Hydrogen, LHV
Hydrogen, HHV
Target for scaled-up process (> 50 ton per day)
State of the art (5–10 ton per day)10–12 kWh/kg
1 www.idealhy.eu2 Cardella U., Decker L., Klein H. Large-Scale Hydrogen Liquefaction. Economic viability. ICEC 26 - ICMC 2016 conference
21Courtesy of Linde Kryotechnik AG.Cardella U., Decker L., Klein H. Large-Scale Hydrogen Liquefaction. Economic viability. ICEC 26 - ICMC 2016 conference
Targeted liquefier efficiency improvement
Targeted specific cost improvement
22
Courtesy of Linde Kryotechnik AG.U. Cardella, L. Decker, H. Klein. Roadmap to economically viable hydrogen liquefaction, International Journal of Hydrogen Energy, Volume 42, Issue 19, 2017, Pages 13329-13338.
More than 50 % specific
liquefaction cost is targeted
from scaling-up, which enables
reductions in both specific
CAPEX and specific OPEX.
23
Acknowledgements
This publication is based on results from the research project Hyper,
performed under the ENERGIX programme. The authors acknowledge
the following parties for financial support: Statoil, Shell, Kawasaki Heavy
Industries, Linde Kryotechnik, Mitsubishi Corporation, Nel Hydrogen and
the Research Council of Norway (255107/E20).
Conversion of ortho-H2 to para-H2
• Hydrogen exists in two different spin isomers and thus energy levels
• At ambient temperature, an equilibrium hydrogen mixture consists of:
• 75 % ortho-hydrogen – higher energy level, parallel spin
• 25 % para-hydrogen – lower energy level, antiparallel spin
• In liquid state, the equilibrium composition is close to 100 % para-H2
• Without conversion during liquefaction, almost 20 % of the liquid would
evaporate within the first 24 hours of storage, due to spontaneous conversion
• The heat of spontaneous conversion is higher than the heat of
evaporation at liquid storage conditions25
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