University of Technology Gothenburg SHIPPING AND MARINE TECHNOLOGY MARTIME ENVIRONMENT AND ENERGY SYSTEMS. Cecilia Gabrielii Lecturer, PhD

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1 University of Technology Gothenburg SHIPPING AND MARINE TECHNOLOGY MARTIME ENVIRONMENT AND ENERGY SYSTEMS Cecilia Gabrielii Lecturer, PhD

2 Agenda LNG - what is it? Why LNG as a marine fuel? Production, storage, transport Properties, characteristics and behavior Hazards

3 What is LNG? Natural gas that is converted to liquid for ease of storage/transport LNG takes up about 1/600th of the volume of natural gas. Natural gas becomes a liquid (LNG) at approximately -162 C Transported and stored at around -162 LNG s extremely low temperature makes it a cryogenic liquid. LNG constitutes mostly of methane

4 LNG produced for transportation purposes Gas market is often far from the natural gas source LNG offers greater flexibility than pipeline gas There are challenges with storing / transporting LNG

5 Outside of storage tanks LNG quickly warms back into natural gas Volume expansion 600

6 Inside storage tanks LNG eventually warms back into natural gas so called Boil Off Gas BOG Volume expansion 600 Tank pressure increases 20 C -162 C

7 LNG as a marine fuel A way to reduce air pollution

8 Emissions from ships running on fuel oil SOx - sulphur oxides NOx - nitrogen oxides SOx NOx PM - particles PM CO 2 CO 2 - carbon dioxide Negativ impact on the environment and/or health

9 SOx (sulphur oxides) emissions

10 Regulations on SOx emissions from ships GLOBAL SECA

11 Sulphur emissions control areas (SECAS) 2015: max 0.1% sulphur content in the fuel

12 Different ways to comply with SECA 2015 Continue running on high-sulphur fuel oil and install exhaust gas cleaning equipment - scrubbers Run on low-sulphur fuel oil with 0,1% sulphur New types of fuel, LNG or Methanol (no sulphur)

13 What about the other emissions? CO 2 : Demand for reduction of Green House Gases EEDI (energy efficiency design index) for new ships PM: Expecting new regulations NOX: SOx NOx PM CO 2

14 Regulations on NOx emissions from new ships 2011: 20% reduction - global 2016: 80% reduction only in ECA

15 Emission controlled areas (today) Expected future ECA for NOx

16 Governing factors for selecting future marine fuels Max 0.1% sulphur fuel in SECA - from 2015 Max 0.5% sulphur fuel globally - from 2020/ % reduction in NOx emissions (from 1 Jan 2016, new ships, ECA) Demand for reduction of Green House Gases lowest possible EEDI Expecting new special limits for PM

17 Emissions from LNG fuelled ships - compared to MDO SOx practically zero NOx % reduction PM negligible CO % reduction Net reduction of Green House Gases: 15-20%

18 Green house gases (GHG) Methane is a 25 times stronger green house gas than CO 2 Due to a small amount of unburned methane in the engine the net reduction of GHG emissions is only 15-20%

19 From gas field to users

20 Exploration/production

21 Natural gas reservoirs Conventional gas - porous reservoir with sufficient permeability to allow gas to flow to producing well Unconventional gas - Deposits in relatively impermeable rock formations artificial pathways have to be created

22 What is natural gas? Crude oil and natural gas constitute of hydrocarbons Gas from different sources have different chemical composition Methane is by far the major component, over 80%

23 Typical natural gas composition And impurities such as hydrogen sulphide, water and mercury

24 From the natural gas production/exploration plant Natural gas is transported in pipelines to the processing and liquefaction plant

25 Processing and liquefaction plant Composition before Composition after

26 Processing and liquefaction plant -162 C

27 Processing before liquefaction Removing of impurities hydrogen sulphide (H 2 S) and mercury Removing components which would freeze at the liquefaction water vapour and carbon dioxide Removing heavier hydrocarbons raw materials to industry or used as fuel at the plant

28 Liquefaction The gas is cooled down in stages until it is liquefied, at -162 C Nitrogen removal Nitrogen decreases the energy content in LNG Nitrogen

29 Typical LNG composition Others: Ethane < 4% Propane < 1% Butane < 0.5% Nitrogen < 0.5%

30 LNG can now be transported wherever needed

31 Transport of LNG By truck very short distances specialised, double-skinned tank trucks By ships long distances in a special purpose LNG carrier good insulation and a double hull design

32 LNG Carriers 50 years ago Methane Princess - the first ship built purposely for transport of LNG Capacity of m 3

33 LNG Carriers - today 350 carriers - average capacity of m 3 Specifically designed to contain LNG at or near atmospheric pressure at a cryogenic temperature of approximately -162 C

34 How to keep LNG in its liquid form? Tank insulation will not keep the LNG cold enough to remain as a liquid by itself Auto-refrigeration LNG stays at near constant temperature if kept at constant pressure. Achieved if the LNG vapour boil off (BOG) leaves the storage tank -162 C 20 C

35 How to handle the boil-off? Use it as fuel in the propulsion machinery Steam turbine propulsion Dual fuel engines Re-liquefy and send back to the LNG tanks Disposal of boil-off gas to atmosphere Only in an emergency situation

36 LNG Carriers two different tank systems Spherical Membrane

37 Spherical - self-supporting - tank Tank shell: 30 mm aluminium or 9% nickel steel Insulation: 220 mm of e.g. polystyrene foam Spherical; high degree of safety against fracture or failure

38 Membrane tanks not self-supporting - the inner hull forms the load bearing structure very thin primary barrier to 1.5 mm stainless steel or nickel alloy utilize the hull shape more efficiently larger cargo capacity must always be provided with a secondary barrier

39 Secondary barrier temporary containment of a leakage of LNG through the primary barrier, and prevent a too low temperature of the ships structure

40 Which type is the best? Spherical Membrane Simple construction Independent from the ship's hull Can be partially pressurised Larger cargo capacity Less tank weight Lower windage area

41 LNG has arrived at the import terminal! Onshore terminal or floating (FSRU)

42 Feeder vessel to intermediate terminal Feeder vessel Regional distribution of LNG Typical cargo capacity: m 3

43 At the receiving terminal (import / intermediate) LNG is either re-gasified into natural gas delivered to the gas grid or LNG is delivered to a truck or bunker vessel which deliver it to a LNG fuelled vessel LNG is re-gasified just before entering the engine

44 Components at the terminal Unloading arms Cryogenic pipelines Storage tanks Boil-Off Gas (BOG) compressors and re-condensers Pumps Vaporisers (re-gasifiers)

45 Onshore terminal storage tanks Flat bottomed tanks (FBT) - stores LNG under atmospheric pressure Semi-pressurised tanks - stores LNG under pressure (approx. 10 bar) withstand cryogenic temperatures maintain the liquid at low temperature minimize the amount of evaporation (BOG)

46 Example of LNG bunkering terminal From the atmospheric FBT : High pressure pump Regasification To the natural gas grid From the semi-pressurised tanks: To truck or bunker vessel

47 Storage tanks how to prevent leakage of LNG? LNG tanks have more than one means of containment. Primary the tank which holds the LNG, with insulation Secondary dikes, impoundment dams around storage tanks, or: second tank around the primary storage tank

48 Atmospheric pressure tanks (FBT tanks) Large tanks (> m 3 ) Built on site on flat-base concrete foundations A system for BOG is needed Different types Double containment Full containment

49 Double containment tank In case of failure/leakage: LNG is contained by a concrete bund wall But uncontrolled release of LNG vapour to the ambient

50 Full containment tank In case of a failure / leakage The outer tank - concrete wall - is capable of containing both LNG and LNG vapour (controlled venting of the vapour)

51 Handling of the Boil-off Gas (BOG) % of the total tank content per day -162 C This gas is captured and sent to the pipeline (gas grid), or re-injected into the LNG carrier during the unloading of the ship, or re-condensed and sent back to the storage tank, or sent to the flare - only in abnormal or accidental situations

52 Handling of the Boil-off Gas (BOG) BOG

53 Regasification LNG is warmed back to natural gas and delivered by pipeline to consumer.

54 Regasification The atmospheric storage tanks are equipped with submerged pumps that transfer the LNG towards high-pressure pumps.

55 Regasification The pressurised LNG is then turned back into a gaseous state in vaporizers (warmed by seawater).

56 Example of LNG bunkering terminal From the semi-pressurised tanks: To truck or bunker/vessel

57 Pressurised tanks Small scale tanks - typically 1000 m 3 Cylindrical tanks designed to resist pressures of up to approx. 10 bar. The BOG can remain in the tank Simple tank arrangement Two types Double integry Full integry

58 Double integry pressure tank In case of a failure/leakage a pool / collection basin directing any spillages away in a safe location.

59 Full integrity pressure tank In case of a failure/leakage Both the inner and the outer containment are constructed from cryogenic steel being able to hold the LNG.

60 Example of LNG bunkering terminal From the semi-pressurised tanks: To truck or bunker/vessel

61 Bunker vessel Smaller and more manoeuvrable compared to an LNG feeder vessel Typical cargo capacity: m 3 Bunker vessel bunkering LNG-fuelled ship

62 Floating LNG Terminal (FSRU)

63 FSRU - Floating Storage and Regasification Unit m 3 membrane tanks

64 FRSU

65 Bunker vessel loading at FSRU

66 Chemical and physical properties fundamental for understanding and predicting LNG behaviour distinguish between the properties as a liquid and as a gas/vapour the properties which make LNG a good source of energy can also make it hazardous if not adequately contained properties, characteristics and behaviour of LNG differ significantly from conventional marine fuels

67 Chemical and physical properties Chemical composition Boiling point - cryogenic Density volume expansion Flammability Others

68 LNG s principal hazards result from its Cryogenic temperature Flammability characteristics Vapor dispersion characteristics If an LNG release occurs, there is an immediate potential for a range of different outcomes and types of consequences.

69 Typical chemical composition of LNG others: Ethane 4% Propane <1% Butane < 0.5% Nitrogen < 0.5%

70 Hydrocarbons in LNG Name of the hydrocarbon Number of carbons Boiling point atm. pressure Methane C Ethane 2-89 C Propane 3-42 C Butane 4 0 C Nitrogen: -196 C

71 Boiling point at atmospheric pressure water 100 C LNG -162 C Outside of storage tanks LNG quickly warms back into natural gas

72 Higher pressure higher boiling point LIQUID LNG is always stored at its boiling point! GAS Temperature [ C)]

73 Density A liquid has a higher density than a gas/vapour! Liquid Gas

74 Volumetric expansion 1 m 3 LNG corresponds to around 600 m 3 natural gas The reason why natural gas is stored and transported as LNG A small leakage of LNG results in a large (flammable) gas cloud

75 Density LNG (liquid) Lower density than water, i.e. LNG floats on water But becomes a vapour pretty soon LNG: 450 kg/m 3 Water: 1000 kg/m 3

76 Density LNG vapour (natural gas) At temperature below -110 C: LNG vapour is heavier than air LNG vapour blankets the ground, the cloud travels with the wind At temperature above -110 C: LNG vapour is lighter than air LNG vapour will rise when sufficiently warmed by ambient air

77 How to recognize LNG (natural gas)? colourless and odourless The white clouds that form at a leakage of LNG is not LNG/natural gas Cold LNG vapours will make the moisture in the air condense causing the formation of a white cloud (fog)

78 This is not a leakage of LNG The cold LNG pipe will make the air moisture to condense

79 What about flammability? Yes, natural gas burns - this is why it can serve as a fuel! LNG (liquid form) does NOT burn But, LNG begins vaporising immediately upon its release Flammability properties Flashpoint Flammability range Auto ignition temperature Minimum ignition energy

80 The fire triangle Fuel (flammable vapor) Air (oxygen) Heat - source of ignition e.g. spark, open flame, high temperature surface

81 Flash point flammable vapour The lowest temperature at which a liquid gives off sufficient vapour to form a flammable mixture with air above the liquid surface. LNG MDO & HFO Flash point -187 C >60 C Ships using fuels with flashpoint < 60 C must comply with a new international regulation - IGF Code

82 Flashpoint LNG: -187 C -43 C 20 C >60 C

83 Flammability range - mixture with air Flammability range Vol% in air LNG 5-15% 1-7% MDO, HFO and gasoline

84 LNG flammability range: 5-15% Above UFL (above 15%): not flammable In a closed storage tank, the percentage of methan is almost 100% Below LFL (below 5%): not flammable A small leakage of LNG from a tank in a well-ventilated area is likely to rapidly mix and quickly dissipate to lower than 5% in air.

85 The fire hazards differs from other fuels due to its vaporisation and dispersion behaviour. A leakage of LNG evaporates to an elongated gas cloud that spreads by the wind until it warms and becomes buoyant and rises A small leakage of LNG will disappear rather quickly The visible fog is a reasonable indication of the boundaries of the flammable mixture.

86 Engine room fire oil fuelled ships 80% of all fires in the engine room start with fuel coming in contact with hot surface as a result of pipe failure LNG fuelled ships: the risk for engine room fire is SMALLER, why??

87 Auto ignition temperature ignition without flame/spark The lowest temperature at which the gas will be ignited by a hot surface LNG HFO, MDO Auto ignition temperature 540 C C LNG has a higher auto-ignition temperature than conventional marine fuels. not easily ignited by hot surfaces And, smaller risks for fuel leakage from pipes Double pipes

88 Minimum ignition energy - ignition by a flame or spark The minimum ignition energy for LNG is 100 times lower than for HFO LNG HFO/MDO Minimum ignition energy in air 0.27 mj 20 mj LNG releases are not easily ignited by hot surfaces but low energy sparks represents a higher risk Electrical spark, static electricity

89 Flammability properites - summary ( ) ( ) LNG MDO/HFO Flammability range (in air) 5-15% 1-7.5% Flashpoint -187 C >60 C Auto ignition temperature 537 C C Minimum ignition energy in air 0.27 mj 20 mj

90 LNG s principal hazards result from its Cryogenic temperature Flammability characteristics Vapor dispersion characteristics If an LNG release occurs, there is an immediate potential for a range of different outcomes and types of consequences.

91 LNG spills consequences depends on: Leakage on ground or sea Atmospheric or pressurised tanks (pipe) Ignition source or not Confined or unconfined Small or large leakage

92 LNG spills on ground or sea LNG spill Sea Ground Quick evaporation Slower evaporation LNG vaporises five times more quickly on water than on land

93 Quick evaporation- Rapid Phase Transition A spill of a large quantity of LNG in a hot fluid like the sea Sudden phase change from liquid to gas Can result in a damaging physical explosion (pressure pulses) Like the small explosions when heating cooking oil with small amounts of water inside

94 LNG spill - from atmospheric or pressure tanks LNG spill From atmospheric tank From pressurised tank Evaporation rate depends on water / ground Instantaneous evaporation and larger vapour release LNG vaporises instantaneously from pressurised tanks

95 LNG spill - ignition source or not LNG spill Flammable LNG vapour Ignition source: Fire No igntion source: Evaporates and rises until the pool is gone

96 Different types of fire after ignition Flash fire (vapour cloud fire) Jet fire Pool fire BLEVE ( fire ball ) The type of fire depends on Early or delayed ignition Atmospheric or pressurised leakage

97 Pool fire - early ignition of atmospheric LNG spill A leakage forming a liquid pool on water surface or on ground Some of the liquid will evaporate quickly if flammable vapour finds an ignition source there will be a pool fire High radiant heat The fire burns until the fuel is consumed

98 Flash fire - delayed ignition of the vapour cloud No ignition source at the place of LNG release Before the vapours reach -110 C they disperse along the ground Vapour clouds may ignite at the edge if they meet an ignition source the smallest spark capable of igniting is not visible in daylight

99 Pool fire after vapour cloud fire (flash fire) The ignited dispersed cloud may burn backward to the release point Ignites the vapour above the pool and generate a pool fire

100 Summary - Pool fire and vapour cloud fire (flash fire)

101 Some words about fire fighting Remove the fuel source (i.e. stopping the leak) Do not extuingish with water may cause the fire to flare up and intensify The fires are very hot Water can be used to cool surfaces around the fire divert the vapours away from possible ignition sources

102 Ignition atmospheric or pressurised LNG spill Flammable LNG vapour Delayed ignition Flash Fire (Vapour cloud fire) Early ignition Pool fire Jet Fire Fire Ball High pressure leakage Pool fire

103 Jet fire - direct ignition, pressurised leakage burning jets as the results of gas or liquid release from pressurised systems (pipes, hoses, tanks) that are directly ignited High velocity and very hot Local effect For LNG stored at low pressures as a liquid this type of fire is unlikely. could occur during unloading or transfer operations when pressures are increased by pumping

104 LNG trapped in piping (bunker lines) LNG is not, unlike HFO och MDO, a static liquid, which can be stored (remain) in pipes and flanges LNG trapped in the piping : heat ingress will cause a pressure build-up (volume expansion 600) can cause a pipe burst Example 70 bar pressure after one hour

105 Ignition atmospheric or pressurised LNG spill Flammable LNG vapour Delayed ignition Flash Fire (Vapour cloud fire) Early ignition Pool fire Jet Fire Fire Ball High pressure leakage Pool fire

106 BLEVE ( Fire Ball ) - fire outside pressurized tank BLEVE: Boiling Liquid Expanding Vapour Explosions A fire close by heats the pressurized tank LNG will evaporate and raise pressure on the inside. In the event of a tank rupture: the boiling liquid simultaneously expands and ignites

107 LNG spills consequences depends on: Leakage on ground or in water Atmospheric or pressurised tanks (pipe) Ignition source or not Confined or unconfined

108 Confined or unconfined LNG spill Ignition Flammable LNG vapour No ignition Confined Fire Unconfined Evaporates and rise until the pool is gone Explosion - Flash fire or pool fire - continue to as a pool fire until the pool is gone. LNG vapours are NOT explosive in open air the radiant heat of LNG fires is considered the primary hazard

109 Environmental consequenses of a spill Spill LNG MDO/HFO Ocean Negligible Significant impact Atmosphere Significant impact as greenhouse gas Volatile organic compound Methane is a 25 times stronger green house gas than CO 2 Venting LNG (natural gas) to the atmosphere shall always be avoided!

110 LNG (spill) - Cryogenic hazards Material- brittle fracture Human cold burns

111 Cryogenic brittle fracture If LNG spilled on unprotected carbon steel

112 Cryogenic burns LNG in contact with skin will cause cold burns Treating a cold burn on the skin: Warm with the hand or wollen material. Place in warm water, at about +42 C for minutes. Or, wrap in blankets and let circulation reestablish naturally.

113 Non-toxic Non-carcinogenic Other health aspects Asphyxiate -suffocating LNG HFO/MGO On your hands Causes frost bites Can be carcinogenic Toxic No Yes Carcinogenic No Yes Asphyxiate Yes, in closed spaces No

114 Oxygen deficiency - asphyxiation If oxygen is displaced from a space by LNG vapours or inert gases

115 Summary: Characteristics that make LNG safer than conventional marine fuels: Non-toxic Vapours are lighter than air (>-110 C) Storage tanks are thick, double walled Double pipes Not explosive in open air Less flammable High auto-ignition temperature