Refrigeration (Kylteknik)

course # 424519.0 v. 2018

5. Low temperatures, liquefied gases, Stirling engines, LNG, dry ice

Ron Zevenhoven Åbo Akademi University Thermal and Flow Engineering Laboratory / Värme- och strömningsteknik tel. 3223 ; [email protected]

ÅA 424519 Refrigeration / Kylteknik

5.1 Gas refrigeration and liquefaction

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 2/90 Gas liquefaction options . Liquefied gases can be produced by cooling a gas until it partially forms a liquid, and removing this liquid product, by gas-liquid separation. . The necessary cooling effect can be achieved by expansion cooling – Using a turbine or other expansion machine (allows for very limited liquid formation): reversed Brayton cycle, reversed Stirling cycle – Using a throttling device, making use of the Joule-Thomson effect . For pre-cooling, a vapour - compression process can be 2017) (Feb. http://www.linde-gas.com/en/index.html Pictures: used

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5.2 Stirling cycles

See also A11: chapter 13.10 and TV08 A09: chapter 11.6

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 4/90 Carnot, Stirling, Ericsson cycles

. Process steps 1-2, 2-3, 3-4, 4-1: . Carnot cycle: reversible – Heat addition at constant T – Adiabatic expansion T,s and p,v – Heat rejection at constant T diagrams for – Adiabatic compression Carnot → . Stirling cycle: reversible and – Heat addition at constant T – Heat rejection at constant v Stirling ↓ – Heat rejection at constant T power – Heat addition at constant v cycles . Ericsson cycle: reversible – Heat addition at constant T – Heat rejection at constant p – Heat rejection at constant T – Heat addition at constant p

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Stirling cycle, Stirling engine See for principle also https://www.stirlingshop.de/working-principle-stirling-engine (Nov. 2018)

. Heat is temporarily stored in the regenerator, going from temperature

TH to TL during step 2-3 (and vice versa when returning to state 1) Picture: ÇB98 Picture: T06

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A09 §11.6

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Stirling cycle in reverse: refrigeration /2

A09 §11.6

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 8 Stirling cycle in reverse: refrigeration /3

A09 §11.6

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Stirling cycle in reverse: refrigeration /4

A09 §11.6

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 10 Stirling refrigeration working gas

A09 §11.6

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Stirling engine refrigeration

. The working gas in the cycle is hydrogen or helium (high thermal conductivity!) . The Stirling cycle is difficult to achieve in practice since heat transfer requires temperature differences → regenerator has efficiency < 100%, and pressure drop . Nonetheless of interest due to efficiency potential and (for engines) emissions control (Ford, GM, Philips) Stirling gas refrigerator (Philips) Picture: S90

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TL

TH “The cooler consists essentially of only two moving parts - a piston and a displacer. The displacer shuttles the working gas (helium) between the compression and expansion spaces. The phasing between the piston and displacer is such that when the most of the gas is in the ambient compression space, the piston compresses the gas while rejecting heat to the ambient. The displacer then displaces the gas through the regenerator to the cold expansion space. After this, both displacer and piston allow the gas to expand in this space while absorbing heat at a low temperature.” Picture and source: http://www.ohio.edu/mechanical/thermo/Intro/Chapt.1_6/Chapter3b.html (Nov 2017)

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Stirling refrigeration vs. alternatives . Stirling refigeration devices (”cryogenerators”) allow for cooling down to -250°C at up to several MW cooling power

. Efficiency: COP ~ 0.5· COPcarnot Evaporation . Compact, simple, low noise Stirling . Temperature-range flexible Claude Joule-Thomson

With repeated strokes, lower and lower temperatures can be See (Feb 2017) http://www.stirlingcryogenics.com/ also: reached

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5.3 Joule-Thomson effect (see also 3.3)

See also A11: chapter 2.30

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Gas expansion: Joule-Thomson effect /1 . Throttling (= isenthalpic pressure  T  reduction of gases)  T     0 can have a    0   p  p h temperature effect as a result of  h  T  deviations from ideal gas    0  p h behaviour:  h  h  h(p,T) and     for non  ideal gas Liquid-vapour   dome  p T  T   p   h  using dh   or           p h  h T  T p  T     h     µ     with Joule Thomson coefficient µ  p  JT  p   h  c  p  JT  h     p  T  h T  T p . For the states (for example in a T,s diagram) where

(∂T/∂p)h > 0, reducing pressure will give a lower temperature: the Joule-Thomson effect Picture: S90

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 16/90 Gas expansion: Joule-Thomson effect /2 . At the inversion temperature

of a gas, µJT = 0 . Application: cooling and liquefaction of gases

. Some tabelised data:

Air at 1 atm:

µJT ~ 2K/MPa at ~ 20°C µJT ~ 4K/MPa at ~ -100°C Picture & table: A83

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Gas expansion: Joule-Thomson effect /3

Picture A09

19.11.2018 Åbo Akademi Univ - Thermal and Flow Engineering 18/90 Piispankatu 8, 20500 Turku Using the Joule-Thomson effect . The main application of the J -T effect is the Linde-Hampson process, later also the Claude process, still later also natural gas processing: gases with relatively high vapour pressure . Initially used mainly for liquefaction of air, followed by

distillation to separate air into N2 + O2

. Water and CO2 can be removed at ~ -50°C and -80°C, resp. . Note: during vaporisation of Picture: Ö96 liquid air, more N2 than O2 is vaporised, enriching the

remaining liquid in O2, which can lead to ignition of oil, therefore cooling with liquid nitrogen

(by-product from O2 production!)

is much safer T,x diagram for O2 + N2 at 1 atm

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5.4 Linde-Hampson process (for liquefaction of gases)

See also A11: chapter 13.11 and MMW14: chapter 4.2.5

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 20/90 Linde-Hampson process – ideal /1

1-2 Compression at T = Tin 2-3 Heat exchange 3-4 Throttling 4-6 Liquid removal 4-5 Gas removal 5-7 Heat exchange heat Liquefied gas exchange

Note: massin = massliq @ 6 + massgas @ 5

1 and 7 can be open for air (and p2 for cold gas = 1 bar); Picture: S90 closed loop for other gases

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Data for several gases

Critical Temperatures, Critical Pressures, Boiling Points o o Gas Tc( C) Pc (atm) BP at 1 atm ( C) He -267.96 2.261 -268.94

H2 -240.17 12.77 -252.76 Ne -228.71 26.86 -246.1

N2 -146.89 33.54 -195.81 CO -140.23 34.53 -191.49

Air -140 39 see data N2, O2, … Ar -122.44 48.00 -185.87

O2 -118.38 50.14 -182.96

CH4 -82.60 45.44 -161.49

C2H6 32.27 48.16 -88.6

CO2 31.04 72.85 -78.44

C3H8 96.67 41.93 -42.02

NH3 132.4 111.3 -33.42

Cl2 144.0 78.1 -34.03

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Mass balance: Note: ΔT23 < ΔT57

min = m4 = m6 + m5 Energy balance I:

h3= h4 = x· h5+(1-x)· h6 II

fraction of mass heat liquefied = γ = 1-x Liquefied gas exchange Energy balance II:

m2· h2 = m6· h6+m7· h7

h2 = γ· h6 + (1-γ)· h7 gives I Picture: S90 γ = (h2-h7)/(h6-h7)

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Linde-Hampson process – ideal /3

. For example (see p,h 4 diagram on next page) 3’’ air 290 K, 1 bar → 200 bar 2 1 hair in = 290 kJ/kg = h4 3 Compressor h1 = 255 kJ/kg Cooler after compressor 3’ h = - 40 kJ/kg = h Heat exhanger 2 3 Throttling and liquid removal h3’ = -130 kJ/kg Picture: Ö96 air mass fraction liquefied, γ, from energy balance Some data for air: γ γ min· h1= · min· h3’+ (1- )· min· h4 cp kJ/kg· K 1 bar 300 bar gives γ = (h1-h4)/(h3’-h4) = 0°C 1.006 1.409 0.083 kg / kg -100°C 1.011 1.761

T2 = 120 K, T3’ = 80 K (see also Ö96 – example 6.4)

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 24/90 Linde-Hampson process: p,h diagram tri.org.tw/Refprop/air.gif Source: http://refrigerant.i

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Linde-Hampson process – real states ”*”

1-2* Compression with intercooling 2*-3* Heat exchange with pressure drop 3*-4* Throttling 4*-6* Liquid removal 4*-5* Gas removal 5*-7* Heat exchange Liquefied gas

4* instead of 4: much less liquid product ! Cooling inlet compression with water can give 1-2 With air, if 7 ≠ 7* then cold Picture: S90 air is rejected.

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. Linde process with external pre- cooling process and high pressure to ~50 bar to ~200 bar circulation (for air) Pictures: Ö96

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Linde-Hampson initial cascade process

Compressor . Until 1895 the most Condenser important process, Evaporator used only for Condenser liquefaction of air Evaporator . Uses 4 cooling cycles Condenser in series Evaporator . Relatively small Condenser pressure & temperature ranges per stage Linde’s 4-stage cascade process (here for N2) . Medium is liquefied in 4th stage Picture: Ö96

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5.5 Claude process (for liquefaction of gases)

See also MMW14: chapter 4.2.6

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Claude process - ideal

Similar to Linde process Heat exchange except for: I 2-3 heat exchange I II and then partially: III 3-4 expansion turbine; + 3-5 heat exchange II + III 5-6 throttling Lique- fied 6-8 liquid product gas 6-7 gas product turbine A mix of a Linde process (all flow to throttle) and a gas expansion process (no flow to throttle) Picture: S90 If 4 = 7 then heat exchange III is not needed

19.11.2018 Åbo Akademi Univ - Thermal and Flow Engineering 30/90 Piispankatu 8, 20500 Turku Claude process – real states ”*” 1-2* Compression with intercooling 2*-3* Heat exchange I with pressure drop 3*-4* Expansion with losses$ 3*-5* Heat exchange II with pressure drop Lique- 5*-6* Throttling fied 6*-8* Liquid removal gas 6*-7* Gas removal 7*-9* Heat exchange with pressure drop

6* instead of 6: much less liquid product !

Cooling inlet compression Picture: S90 with water can give 2=2* $ depends on expansion device

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Linde-Hampson vs. Claude process . For the Claude process the optimisation of the mass streams and heat exchange is very important . The Claude process is more complicated, requires less 7) energy input as a result of the expansion machine, nonetheless efficiencies can be as low as ~ 4-6 %. . For liquid air the production is ~ 0.05 - 0.07 kg/kg input air, can be improved to 0.1 - 0.2 kg/kg input air when using pre-cooling to -30 ~ -50°C . The temperature after the compression is very important for overall efficiency . The choice between a Linde or Claude

process depends on size and costs 201 (Feb. http://en.wikipedia.org/wiki/Liquid_oxygen Picture:

. For air, pre-cooling to ~ -50°C for H2O removal, to ~ -80°C for CO2 removal Liquid O2 19.11.2018 Åbo Akademi Univ - Thermal and Flow Engineering 32/90 Piispankatu 8, 20500 Turku Process energy use . The energy input can be Heat Power evaluated from an energy balance Q P for liquid product .. γ· m· h + P = Q + γ· m· h 0 0 . 3’ !!! with fresh gas feed. γ· m at enthalpy h0 and m = mass flow to be compressed. . Power input per kg product: . . P/(γ· m) = Q/(γ· m) + h3’ –h0 Table and picture after Ö96 Energy input for producing liquefied air at 80 Theoretical In practice K at 290 K ambient temperature kWh / kg kWh / kg Linde cascade process (4 stages) 0.32 0.54 Simple Linde process 1.21 2.1 Linde process + pre-cooling 0.70 1.2 Linde process + high pressure circulation 0.45 0.63 Claude process 0.35 0.85

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5.6 Liquefied hydrocarbons

(LNG / methane, LPG) and CO2

See also MMW14: chapter 4..2.4

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 34/90 LNG processing /1 . Liquefied natural gas (LNG) is becoming increasing important, as a substitute for oil and other fossil fuels; liquefaction facilitates long-distance transport (Oct. 2012)

. Methane (CH4) with higher C:H molar ratio than other hydrocarbon fuels, gives less CO2 /kWh power . Typical composition:

CH4 87 - 91 mole-%; C2H6 4 - 11 mole-%; C3H8 < 3 mole-%;

C4H10 < 1.5 mole-%; C5H12 < 0.05 mole-% . The gas is delivered for processing at ~ 90 bar and after removal of

H2S / CO2, H2O, Hg (!), and heavy components (C5+), it is completely liquefied at ~ - 160°C, pressures between 1 and 60 bar . LNG can be used to produce CNG See:: http://www.khi.co.jp/english/rd/tech/154/ne154ts00a.html See:: http://www.khi.co.jp/english/rd/tech/154/ne154ts00a.html (compressed natural gas, 100-250 bar)

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LNG processing /2

LNG processing

Typical ”train” unit size up to 8 MTPA (million tons per annum)

LNG composition More detail: MMVW14 Chapter 2 Often, ethane and/or propane/butane are (partly) removed Source: WE09

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p,h diagram methane CH4 (R-50) ndex.html Source: http://christophe.lauverjat.pagesperso-orange.fr/mava/i

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LPG . Liquefied petroleum gas (LPG) is a liquefied mixture of mainly (>95%) propane plus some similar boiling point hydrocarbons,

mainly butanes. (Oct 2012) . LPG is produced during processing of natural gas and in crude oil refining Propane Production . The atmospheric boiling point & Distribution System of propane is ~ -42°C; LPG can be liquefied by compression and cooling to ~ 12 bar at low ures/propane05/propane.htm temperatures, and can be stored at ~ 15 bar, 40°C Picture ftp://ftp.eia.doe.gov/broch

19.11.2018 Åbo Akademi Univ - Thermal and Flow Engineering 38/90 Piispankatu 8, 20500 Turku Wobbe index

https://en.wikipedia.org/wiki/Wobbe_index (Feb. 2017)

For NG: 35 ... 55 MJ/Nm3 , for pure methane 50.7 MJ/Nm3

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Acetylene, ethylene, CO2, .... Similar to LNG and methane, Picture: D03 a cascade of compression / heat exchange / expansion processes can be used for liquefication of other hydrocarbons with high vapour pressure (ethane, ethylene, ....) and CO2, using hydrocarbons, ammonia, CO2, ...... as refrigerants

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5.7 LNG supply chain and processing

See also MMWV14: chapter 1

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Natural /LNG gas supply chain

Depending on transport distance and amount, transport of NG by pipeline, as LNG or after conversion (Fisher Tropsch GTL fuels, MeOH, DME)

~70% NG transport by pipeline, ~30% as LNG (2014) Picture: Small LNG terminals: 0.01 – 0.3 Mt/a (MTPA), large > 1.5 Mt/a. MMVW14 Qatar > 7 Mt/a, Australia ~15 Mt/a, Nigeria ~24 Mt/a, Russia ~ 10 Mt/a Norway ~ 4 Mt/a Global LNG trade end 2017 ~ 293 Mt/a

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 42 LNG processing before transport

. Pre-chilling and removal of heavy fractions (C2-C5, C6+), bringing CH4 content from ~90% to ~98-99%

. Liquid LNG from flash (to ambinient pressure) to storage ing-doha-2009/fscommand/d01.pdf tanks, flash gas + BOG from storage and ship is compressed and sold e.g. as fuel BOG = . Gas turbines Boil-Off Gas replaced steam turbines for LNG

refrigeration, oge/prost/proceedings/gas-process  less attactive to use flash gas (recompression needed) Picture: http://www.nt.ntnu.no/users/sk (Nov. 2014)

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LNG production from raw NG

N2 removal: 1.quality 2. boiling point 3. roll-over

Picture: MMVW14

. LNG: atm. boiling point ~ -162°C, 87-99% methane, density 430 ~ 470 kg/m3, NG flammibility limits in air LFL ~ 5%-vol, UFL ~15%-vol

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 44 LNG processing: special features rs/ (Nov. 2014) (Nov. rs/

. Gas composition, purification needs: water, Hg, CO2, N2, ”heavy hydrocarbons”, H2S

. Water removal: glycols (DEG or TEG), or adsorbents that also remove ctrica-lp/sideba

CO2 and H2S, using molecular sieves, or alkanol amines (MEA, DEA, ....) . Storage of LNG at ~ -160°C, 1 atm, at 1/600th of the NTP volume requires, of course, insulation, and removing boil-off . Pre-stressed concrete, Al and 9%Ni steel are suitable . A serious challenge is stratification, caused by free convective flow of heated liquid along the walls, towards the upper, m/4q-2012/plant-reports-ecoele liquid-vapour interface. Roll-over can then give sudden and rapid flashing. . ”Aging” and varying LNG input increase the risk

. More detail / source: F05 (e.g. Section 6.4) Picture: http://www.ccj-online.co

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5.8 Liquefied gas, LNG transport

See also MMWV14: chapter 3

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. Liquefied gases can be transported while being refrigerated on ships, trains and trucks (and in principle also on aeroplanes) (Oct.2012) 55007_008_18_l.jpg . One option is to use part of the boil-off as fuel for the vehicle (and to drive the compressor for the refrigerator) . Traffic and public safety may be an issue

. See also http://liquefiedgascarrier.com/ (Nov. 2018) Picture:http://www.kommersant.com/photo/300/DAILY/2005/237/KP_ Picture: http://www.vpsr.cz/lpg-road-tankers (oct. 2012) (oct. http://www.vpsr.cz/lpg-road-tankers Picture:

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LNG transport by ship

Pictures: MMVW14

. Typically 30 000 – 300 000 m3, mostly ~ 130 000 m3 ~ 65 000 tons. T = approx. -169 °C, p = 1.3 ~ 1.7 bar, BOG = 0.05 ~ 0.15 %/day

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 48 Pictures: LNG transport by ship MMVW14

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LNG receiving terminal : model

Picture: MMVW14

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 50 LNG receiving terminal: processing

Picture: MMVW14

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5.9 Natural gas liquefaction

See also MMWV14: chapter 3 and WE09: chapter 6

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Pictures: http://scialert.net/fulltext/?doi=jas.2011.3541.3546&org=11 from article: http://scialert.net/qredirect.php?doi=jas.2011.3541.3546&linkid=pdf and https://www.researchgate.net/figure/289496479_fig1_Fig-1-Pure-and-MR-cooling-curve-in- comparison-to-natural-gas-Helgestad-2009

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LNG liquefaction /1 -35 °C -161°C ~ 0.07 bar gauge (1.07 bar abs) . LNG liquefaction is based on succesive compression, heat exchange and expansion . Currently the propane pre-cooled mixed refrigerant (PPMR / C3MR) process* → covers ~75% of the market needs since the late1970s . A mixed refrigerant (MR) is used for minimal irreversibility losses; the PPMR process uses a mixture of nitrogen, methane, ethane and propane → ldoil.com/Magazine/ . The first steps cool to ~ -35°C to remove heavy components (natural gas liquids, NGL), followed by Joule- Thomson cooling to ~ -160°C Picture: http://www.wor MAGAZINE_DETAIL.asp?ART_ID=2808&MONTH_YEAR=Feb-2006 * APCI (Air Products & Chemicals Int)

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Methane circuit

An important alternative process for LNG liquefaction is the optimised cascade LNG process (OCLP)* based on three refrigerants: propane, ethylene circuits and methane (flash) circuit. Picture: http://www.worldoil.com/Magazine/ MAGAZINE_DETAIL.asp?ART_ID=2808&MONTH_YEAR=Feb-2006 * Phillips Petroleum Co.

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LNG liquefaction /3 ldoil.com/Magazine/

Another important, more recent alternative, process for LNG liquefaction is the the more recent dual mixed refrigerant process (DMR)* based on pre-cooling to -50°C in the (P)PMR cycle (refrigerant propane) and

further cooling and liquefaction in the MR cycle (refrigerant mainly ethane Picture: http://www.wor MAGAZINE_DETAIL.asp?ART_ID=2808&MONTH_YEAR=Feb-2006 + propane). Advantages: high efficiency, lowest specific costs. * Shell

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Single mixed refrigerant (SMR) loop process Liquefin™ process Mixed fluid cascade process Source: WE09

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NG liquefaction power consumption

Table: MMVW14

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5.10 Liquefied gas, LNG storage

See also MMVW14: chapter 1.4.6

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Liquefied gas storage spheres Liquid level . Storage of liquefied gases can be accomplished at pressures near

1 atm using a spherical tank with a Power free liquid surface STORAGE . Isolation materials minimise the Throttle ”boil-off” gas, BOG typically

~ 0.05 % per day Condenser . The tank can be considered to be the evaporator of a vapour- compression cycle: the boil-off is extracted, compressed, condensed and throttled to the tank pressure . The two-phase mixture returned to the tank gives a cooling effect that exactly compensates for heat leaking in during steady-state operation . For very low-temperature boiling gases like methane, a cascade refrigeration process can be used with propane, freons, water, ..

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. Many liquefied gases can be

stored in gas storage spheres 2012) (Oct. gram.gif at atmospheric pressures, for 26631_pancevo_300_ak.jpg 2012) (Oct. example air, O2, N2 at ~ -190°C

. CO2 is stored at ~ -20°C at 20 bar (triple point at 5.1 bar; if de-pressurised below that it will give a solid : dry ice! ) . Ammonia can stored at uk/media/images/38726000/jpg/_387 atmospheric pressure at -33°C . Alternatively, gases can be

stored without refrigeration in http://scifun.chem.wisc.edu/chemweek/CO2/CO2_phase_diaPicture: pressurised gas bottles. Picture:http://newsimg.bbc.co. 19.11.2018 Åbo Akademi Univ - Thermal and Flow Engineering 61/90 Piispankatu 8, 20500 Turku

LNG storage tanks, roll-over

. Heat transfer inside LNG storage tank, roll-over Pictures: MMVW14

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 62 ÅA 424519 Refrigeration / Kylteknik

5.11 LNG off-loading, regasification

See also MMW14: chapter 1.4.6

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LNG regasification /1

. At the destination, LNG must be returned to the gaseous state for transport and distribution, gradual warming from -163°C to > 0°C at 60 ~ 100 bar or more. . Also, to recover energy: ~ 8% of LNG energy is used for liquefaction! . If possible, sea-water trickle-type heat exchangers (made of wood, or Ti-based metal) are used; if needed some of the gas is burned to produce heat. . In some cases, contents of

N2 and/or C2+ are adjusted. . See: http://www.saggas.com/en/proceso-de-regasificacion/

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Port of Sagunto ,

(East coast of Spain) n/proceso-de-regasificacion/ Installed capacity 1.150.000 Nm3/h Vaporisers (4x seawater, 1x submerged combustor) . Status Finland (Nov. 2018): – Rauma, Hamina: building permission 2018 ? – Tornio Manga summer 2018 (Nov. 2017) (storage capacity 0.05 Mm3) Pictures: http://www.saggas.com/e – Pori: autumn 2016 (storage capacity 0.015 Mt, 0.03 Mm3) . – Porvoo: LNG production 2010 (0.02 Mt/a, 3x700 m3 storage)

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 65

Off-loading: LP compression, BOG condensation, HP compression /1

. LP sendout pumps: ~ 1.3  ~ 9 bar

typical

Pictures: MMVW14

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 66 Off-loading: LP compression, BOG condensation, HP compression /2

.  After LP pump 1.3 9 bar, BOG recondenser Picture: at ~ 9 bar, followed by HP pump  120 bar MMVW14

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 67

Off-loading: LP compression, BOG condensation, HP compression /3

. LP sendout pumps: ~ 9  ~ 120 bar

typical

Pictures: MMVW14

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Pictures: . Open Rack Vaporisation (ORV) : ~ 70% MMVW14

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Regasification / vaporisation /2

water

. Submerged Combustion Vaporizer (SCV): ~20% Pictures: MMVW14

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 70 Regasification / vaporisation /3

. Intermediate fluid . Shell-and-tube Pictures: vaporiser vaporiser process MMVW14

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Regasification / vaporisation /4

. Hydrocarbon heat transfer fluid process Pictures: MMVW14

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 72 Regasification / vaporisation /5

. Ambient air Pictures: vaporizer MMVW14

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Regasification / vaporisation /6

As for yet another option for recovery of LNG cold energy: Stirling engines !

. Use of cold with organic Rankine cycle (ORC) Pictures: closed (left) or open (right) MMVW14

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5.12 FPSO: floating production, storage and off-loading for LNG

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FPSO floating production, storage and offloading

. For example, the Lithuanian nal- floating storage and regasification unit (FSRU), built for Lithuania’s liquefied natural gas (LNG) terminal

at Klaipéda; storage ia/energy/floating-lng-termi 3 (27.10.2014)

capacity 170 000 m . klaipeda.d?id=66226156 . Compared to on-shore equipment, besides energy efficiency extra attention to compactness and safety . Mixed refrigerant (MR) processes independence-sails-into- Picture: http://en.delfi.lt/lithuan need less equipment, while pure refrigerant cycles need more stages Single Mixed Refrigerant (SMR) . https://en.wikipedia.org/wiki/Klaip%C4%97da_LNG_FSRU Process (see L11)

Åbo Akademi Univ - Thermal and Flow Engineering Piispankatu 8, 20500 Turku 19.11.2018 76 NG liquefaction for FPSO

. LNG liquefaction processes for FPSO studied by Lee et al. (2011)

See also: . http://www.mustangeng.com/NewsandIndustryEvents/Publications/Publications/ midstream_LNG_Journal_Feb08.pdf (2008) . http://www.airproducts.com/~/media/Files/PDF/industries/lng/en-lean-gas-article.pdf (2013)

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ÅA 424519 Refrigeration / Kylteknik

5.13 Hydrogen

See also http://www.hydrogen.energy.gov (Nov 2018)

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. Hydrogen is (was?) seen, especially by politicians, as a ”solution” to the ”energy production” and greenhouse effect problems

. However, hydrogen is not a fuel that can be extracted from 2012) (Oct. rogen_new.jpg a natural resource but must be produced . Options for hydrogen production are – From natural gas or bio-gas by reforming with steam and/or oxygen – From coal (or peat or wood or .....) by gasification – By electrolysis of water, using electricity from nuclear power or a

renewable source (wind, solar, ...) com/images/The_Auto_Blog/BMW_hyd – Fermentative and other micro-organism systems

. Separation of H2 from syngas (CO/H2/...) or other gas mixture can be accomplished with for example pressure swing absorption (PSA) methods or membranes

. Often concentrated CO2 is a by-product → CO2 sequestration http://www.partstrain. Picture:

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Hydrogen liquefaction /1

. The energy content per volume of gaseous hydrogen is low; er/slide6.html (Oct. 2012) er/slide6.html

even in liquefied form it is less (Oct. 2012) 2 than that of for example gasoline

. Compression of H2 is very energy consuming; for example compression to 20 bar can cost

10% of the heating value energy ~jlandstr/planets/webfigs/matt . Liquefaction requires temperatures below 33 K

(Tcrit), for atmospheric pressure 20 K. . For the Joule-Thomson effect a temperature < 200 K is needed Picture: http://www.astro.uwo.ca/ Source & picture: http://www.oilcrash.com/articles/h2_eco.htm#5.

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. Cooling of H2 is accomplished by . Current energy requirements for prn.pdf (Oct. 2012) prn.pdf multi-stage compression and H2 liquefaction are in the order of expansion coupled with counter- 30-60 MJ (8-17 kWh)/kg liquid H2 flow heat exchange and energy (theory : 14.1 MJ/kg) for a plant recovery by expansion turbines, producing > 100 kg/h based on the Claude process: . I. Compression to ~ 50 bar, removal of compression heat . II. Pre-cooling with liquid nitrogen TCD/Publications/PDF/te_1085_ to ~ 80 K / ~ - 196°C . III. Expanding and further cooling of the H2 (80 → 30 K) . IV. Expanding in a throttling valve → 20 K

. Liquid H2 is then stored at low pressure and T ~ 20 K

(sources: BET04, IAEA99 ) Picture: http://www-pub.iaea.org/M

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Hydrogen liquefaction /3 . Work in the US under the DOE hydrogen program aims at himko.pdf (Oct. 2012) himko.pdf liquefied H2 production at 13-18 MJ/kg, corresponding to ~ 0.5 US$/kg.

. The process is based on the ess05/v_e_1_s hydrogen Claude process, and is referred to as the Combined

Reverse-Brayton Joule- y.gov/pdfs/progr Thomson (CRBJT) expansion Simplified CRBJT cycle cycle K-101 & E-100: compression and cooling . The efficiency of the hydrogen LNG-101 and LNG-102: heat exchange Claude process may be improved TEE-100: flow divider by using He, He/Ne or Ne instead Q-102: turbo-expander of H2 in the gas compression / VLV-100: throttling valve expansion cycle (He-Brayton; MIX-100: mixes gas from turbo-expander

Ne-Brayton cycle) and from flash separator Picture: http://www.hydrogen.energ

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Note: temperatures up to 100 K only Source: http://refrigerant.itri.or

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H2 transport and storage /1

. Hydrogen can be stored as a compressed gas, in liquefied form or as solid hydrides. For large amounts, underground storage in aquifers and depleted oil/gas reservoirs can be considered. nces-in-hydrogen-storage (Oct. 2012) nces-in-hydrogen-storage (Oct. . Metal hydride (MH) storage devices (as High pressure H2 transport developed by Ovonics) can store up to three times as much hydrogen in the same volume as can be stored using high pressure methods edu/naftc_enews/2005/08/07/adva Liquefied H2 transport

H storage as metal hydrides (≈ 340 bar) 2 http://naftcenews.wvu. Pictures:

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. Liquefied hydrogen pipeline .html (Oct. 2012) .html .html (Oct. 2012) .html (a few 100 m) at Cape Canaveral (FL);

several 1000 km of pressurised H2 pipeline exist worldwide dex_apollo_saturn2 ennstoffzelle.de/e/h2/haupt3e photos.com/in

An LH2 vessel Pictures: http://www.innovation-br

LH2 storage at NASA Picture http://www.apollomission

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ÅA 424519 Refrigeration / Kylteknik

5.14 Dry ice

See also A11: chapter 6.8

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Throttling rYg/$_32.JPG?set_id=880000500F of a saturated liquid: A  B

below

triple sublimation s/NTY2WDg0OQ==/z/nuMAAOSwcnpTq point line at 1 atm only at –78.5 °C gas + solid Picture: A11 Picture: http://i.ebayimg.com/00/

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Dry ice (solid CO2) production /2

Here, heat rejection in condenser

at 25°C to an NH3 v-c cycle

Picture: A11

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. A83: P.W. Atkins ”Physical chemistry”, 2nd ed., Oxford Univ. Press (1983) . A11: R. C. Arora ”Refrigeration and air conditioning”, 2nd. Ed. PHI Learning Private Limited, New Delhi (2011) Chapter 2.30, 6.8, 13.10-11, . A09: Refrigeration and air conditioning”, 3rd Ed. Tata McGraw-Hill, New Delhi (2009) . BET04: U Bossel, B. Eliasson, G. Taylor ”The future of the hydrogen economy: bright or bleak?” (2003, 2004) http://www.oilcrash.com/articles/h2_eco.htm#nota_01 . D03: İ. Dinçer “Refrigeration systems and applications” Wiley (2003) . F05: T.M. Flynn “Cryogenic engineering” 2nd Ed. Marcel Dekker (2005) . IAEA99: “Hydrogen as an energy carrier and its production by nuclear power” IAEA-TECDOC--1085 IAEA, Vienna (Austria) (1999) . L11: S Lee et al., “The study on a new liquefaction cycle development for LNG plant” Int. Gas Union Res. Conf. 2011 (15 p.) http://members.igu.org/IGU%20Events/igrc/igrc2011/igrc-2011- proceedings-and-presentations/poster-papers-session-4/P4-22_Sanggyu%20Lee.pdf/@@download/file/P4- 22_Sanggyu%20Lee.pdf

For some p,h diagrams: https://www.chemours.com/Refrigerants/en_US/products/index.html (accessed Nov. 2018) http://christophe.lauverjat.pagesperso-orange.fr/mava/index.html (accessed Nov. 2018) 19.11.2018 Åbo Akademi Univ - Thermal and Flow Engineering 89/90 Piispankatu 8, 20500 Turku 7) Sources #5 /2

. ME06: S. Mokhatab, M.J. Economides, World Oil Magazine 227(2) (Feb 2006) http://www.worldoil.com/February-2006-Process-selection-is-critical-to-onshore-LNG-economics.html . MMVW14: S. Mokhatab, J.Y. Mak, J.V. Valappil, D.A. Wood, Handbook of Liquefied

Natural Gas, Elsevier / Gulf Profess. Publ. (2014) Chapter 1,(2),3,4 (Feb. 201 /gifs/Kol24lg.JPG see https://abo.finna.fi/Record/alma.1238231 incl. E-book . WE09: X. Wang, M. Economides, ”Advanced natural gas engineering,” Gulf Publ. Co. (2009) . S90: A.L. Stolk ”Koudetechniek A1”, Delft Univ. of Technol. (1990) . TV08: D,G. Thombare, S.K. Verma. ”Technological developments in the Stirling cycle engines”, Renew. Sustain, Energy Rev. 12 (2008) 1-38 . Ö96: G. Öhman ”Kylteknik”, Åbo Akademi Univ. (1996)

http://users.abo.fi/rzevenho/Kylteknik%20_Ohman%2019962000.pdf Picture http://www.eq.uc.pt/~abel

. See also: Martinez, I. ”Lectures on Thermodynamics” – lecture 18 (English or Spanish) http://webserver.dmt.upm.es/~isidoro/bk3/index.html updated and based on “Termodinámica básica y aplicada", Ed. Dossat, Madrid (1992) ISBN 84-237-0810-1 Kamerlingh Onnes Lab Leiden (1924) 19.11.2018 Åbo Akademi Univ - Thermal and Flow Engineering 90/90 Piispankatu 8, 20500 Turku