Technologies for hydrogen liquefaction David 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 (H 2 ) 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/m 3 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 5 Aerospace industry Chemical industries Electronic/semiconductor industry Health care industries Metallurgical industries Fuel cell manufacturers Glass production Food and beverage industry LH 2 LH 2
Rough liquefier capacities in selected regions America: < 300 t/d Europe: 20 t/d Japan: 30 t/d 6
Density ratio: Lqiuid at 1 atm / Compressed gas Purpose of liquefaction Enabling high-density storage and transport at low pressure Transport and storage economics analogous to LNG vs. CNG 1000 100 10 Hydrogen 7 1 0 50 100 150 200 250 300 350 Pressure of compressed gas [bar] Methane
Liquefaction power / Energy content Importance of high hydrogen liquefier efficiency Ratio between liquefaction power (electric) and energy content (heating value) of the liquefied gas 35% 30% 25% State of the art (5 10 ton per day) Large potential for improving hydrogen liquefier efficiency by scaling up train capacity! 20% 15% 10% Hydrogen, LHV Hydrogen, HHV Methane, LHV Methane, HHV 5% Methane Snøhvit LNG (15 000 ton per day) 8 0% 25% 30% 35% 40% 45% 50% 55% 60% Exergy efficiency of liquefaction process
Current liquid hydrogen storage capacity Image source: https://www.nasa.gov/content/liquid-hydrogenthe-fuel-of-choice-for-space-exploration Kawasaki Heavy Industries 9 NASA, USA 3 800 m 3 270 t 20 m JAXA, Japan 540 m 3 38 t 12 m LH 2 truck < 50 m 3 < 3.5 t
Large-scale liquid hydrogen storage Image source: Kawasaki Heavy Industries Existing 50 000 m 3 3 500 t 40 000 m 3 2 800 t JAXA, Japan 540 m 3 38 t NASA, USA 3 800 m 3 270 t 45 m 12 m 20 m LH 2 truck < 50 m 3 < 3.5 t 10
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 11 Final liquid hydrogen state: Typically saturated or subcooled liquid at 1.2 1.5 bar Para-hydrogen content > 95 %
State of the art for hydrogen liquefaction 12 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 OPEX
State of the art for hydrogen liquefaction Hydrogen Claude cycle Liquid nitrogen pre-cooling to 80 K 20 bar H2 feed 20 25 bar LN 2 precooling cycle LN 2 30 C -180 C Hydrogen purification in adsorbers after LN 2 pre-cooling -193 C Adiabatic ortho-para conversion after LN 2 pre-cooling Hydrogen Further continuous ortho-para conversion internally in heat exchangers Final liquefaction by expansion through an ejector, also recompressing boiloff gas from storage 1.2 1.5 bar 3 5 bar Hydrogen Claude refrigeration cycle -242 C -243 C -251 C -252 C 13 1.2 1.3 bar
State of the art for hydrogen liquefaction Oil-free hydrogen piston compressors 2-stage low-pressure compressor 20 bar H2 feed 20 25 bar LN 2 precooling cycle LN 2 30 C -180 C 2-stage high-pressure compressor -193 C Plate-fin heat exchangers filled with catalyst grains on the hydrogen feed side for orthopara conversion Hydrogen 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 1.2 1.5 bar 3 5 bar Hydrogen Claude refrigeration cycle -242 C -243 C -251 C -252 C 14 1.2 1.3 bar
State of the art for hydrogen liquefaction Cryogenic expanders Radial hydrogen turboexpanders 20 bar H2 feed 20 25 bar LN 2 precooling cycle LN 2 30 C -180 C Oil or gas bearings (or magnetic) Dynamic gas bearings are most reliable and the current frontier. Installed in all recent liquefiers in Japan Courtesy of Linde Kryotechnik AG. S. Bischoff, L. Decker. First operating results of a dynamic gas bearing Turbine in an industrial hydrogen liquefier. AIP Conference Proceedings 1218, 887 (2010) Hydrogen -193 C Typically 10 50 kw, up to > 85% isentropic efficiency Oil or gas brakes to dissipate shaft power 1.2 1.5 bar 3 5 bar Hydrogen Claude refrigeration cycle -242 C -243 C -251 C -252 C 15 1.2 1.3 bar
Scaling up liquefier train capacity enables 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 H 2 /Ne to enable 16 the use of turbocompressors instead of piston compressors
Relative exergy loss kw exergy / kw heat transferred] Very tigh heat integration needed to curb thermodynamic losses 4 ΔT between hot and cold side [ C] Cold side ΔT 5 C 3 2 ΔT 4 C ΔT 3 C ΔT Q 1 ΔT 2 C 17 ΔT 1 C 0-260 -250-240 -230-220 -210-200 -190-180 -170-160 Hot side temperature { C] Hot side
Temperature [K] Very tigh heat integration needed to curb thermodynamic losses Composite Curves for a block with 100 ton hydrogen per day capacity 18 300 280 260 240 220 200 180 160 140 120 100 80 60 40 20 0 0 5 10 15 20 25 30 35 40 45 Duty [MW]
Temperature [K] Temperature difference [K] Very tigh heat integration needed to curb thermodynamic losses Composite Curves for a block with 100 ton hydrogen per day capacity 19 300 280 260 240 220 200 180 160 140 120 100 80 60 40 20 0 0 5 10 15 20 25 30 35 40 45 Duty [MW] 9 8 7 6 5 4 3 2 1 0
Liquefaction power / Energy content Targeted liquefier efficiency improvement Up to 50 % reduction of power requirement has been identified by several projects 1,2 35% 30% State of the art (5 10 ton per day) 10 12 kwh/kg 25% 20% Target for scaled-up process (> 50 ton per day) 15% Hydrogen, LHV 10% 25% 30% 35% 40% 45% 50% 55% 60% Exergy efficiency of liquefaction process Hydrogen, HHV 20 1 www.idealhy.eu 2 Cardella U., Decker L., Klein H. Large-Scale Hydrogen Liquefaction. Economic viability. ICEC 26 - ICMC 2016 conference
Targeted liquefier efficiency improvement 21 Courtesy of Linde Kryotechnik AG. Cardella U., Decker L., Klein H. Large-Scale Hydrogen Liquefaction. Economic viability. ICEC 26 - ICMC 2016 conference
Targeted specific cost improvement More than 50 % specific liquefaction cost is targeted from scaling-up, which enables reductions in both specific CAPEX and specific OPEX. 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.
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). 23
Teknologi for et bedre samfunn
Conversion of ortho-h 2 to para-h 2 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-h 2 Without conversion during liquefaction, almost 20 % of the liquid would evaporate within the first 24 hours of storage, due to spontaneous conversion 25 The heat of spontaneous conversion is higher than the heat of evaporation at liquid storage conditions
Density ratio: Compressed gas / Lqiuid at 1 atm Purpose of liquefaction Enabling high-density storage and transport at low pressure Transport and storage economics analogous to LNG vs. CNG 70% 60% 50% 40% 30% Methane Hydrogen 26 20% 10% 0% 0 50 100 150 200 250 300 350 Pressure of compressed gas [bar]