alternative fuel for marine engines

Seminar on “LNG- ALTERNATIVE FUEL FOR
MARINE ENGINES”
Guided by, Submitted by,
Mr. LIPPIN PAULY DELWINKURIYAKOSE
Asso. Prof. JYAMEME044
Dept. of Mechanical S8, ME-A
JECC 1

DEPARTMENT OF MECHANICAL
ENGINEERING
VISION
• To provide quality education of international standards in Mechanical Engineering
and promote professionalism with ethical values, to work in a team and to face
global challenges.
MISSION
• To provide an education that builds a solid foundation in Mechanical Engineering.
• To prepare graduates for employment, higher education and enable a lifelong
growth in their profession.
• To develop good communication, leadership and entrepreneurship skills to enable
good knowledge transfer .
• To inculcate world class research program in Mechanical Engineering. 2

CONTENTS
1. Introduction
2. Importance of LNG
3. Comparison based on emission.
4. Different compositions of LNG
5. Gas quality parameters based on compositions
6. Major findings based on quality of fuel
7. Risk analysis of LNG
8. Properties of LNG
9. Advantages
10. Disadvantages
11. Conclusion
12. References
3

INTRODUCTION
• From the viewpoints of low environmental pollution and the use of
alternate fuel, The International Maritime Organisation (IMO)
introduced regulations to reduce the Sulphur content in fuels to 0.10%
for all ships that pass through emissions control areas .
• At present mainly used marine fuels are Heavy Fuel Oil (HFO), Marine
Gas Oil (MGO), Marine Diesel Oil (MDO).
• From all alternative fuels, LNG as fuel is now a proven and available
reduced emission fuel even though it has some risk factors.
• It is extremely important to analyze and safety evaluate fire and
explosion risk of LNG ships. It is necessary for the proper functioning
of these machines. 4

• For many decades natural gas has been used as fuel for private cars. More
recently it is used in marine engines.
• Liquefied natural gas (LNG) is liquid fluid basically composed of methane,
containing traces of ethane, propane, nitrogen or other components usually
present in natural gas as well, the density of which is 447 kg /m3 .
• LNG is produced by purifying natural gas and super-cooling. . At
atmospheric pressure methane becomes liquid at -162°C. LNG therefore is a
cryogenic liquid. The process is known as liquefaction.
• Natural gas is cooled below its boiling point, removing most of the
compounds found in the fuel. the remaining natural gas is primarily methane
with small amounts of other hydrocarbons.
5

IMPORTANCE OF LNG
• LNG as a fuel shows a large energy to volume ratio.
• LNG combustion is characterized by low levels of production of CO2,
SOx, NOx and particulate matter in comparison to conventional fuels. To
reduce the emission of SOx into the atmosphere the sulphur content of
heavy fuel oils used for marine propulsion will be restricted in the near
future.
• Natural gas prices has been reduced the last few years due to the
introduction of shale gas in the US market. This is a reason that LNG has
improved its competitiveness to HFO, especially on ECA’s areas .
6

COMPARISON BASED ON EMISSION
7
Figure 1 lists the reduction of polluting products of a combustion
engine when using LNG instead of HFO. There is a reduction of 20% of CO2 ,90%
of Nox ,95% of Particulate matters, 95% of SOx emissions.
Fig:1

DIFFERENT COMPOSITIONS OF
LNG
8
Origin Nitrogen
[mol%]
Methane
[mol%]
Ethane
[mol%]
Propane
[mol%]
Butane
[mol%]
Algeria 0.71 88.92 8.41 1.59 0.37
Nigeria 0.03 91.70 5.52 2.17 0.58
Norway 0.46 92.03 5.75 1.31 0.45
Qatar 0.27 90.90 6.43 1.66 0.74
Trinidad and
Tobago
0.01 96.78 2.78 0.37 0.06
Table:1

GAS QUALITY PARAMETERS BASED ON
COMPOSITIONS
9
Origin GCV [MJ/m3] Wobbe number
[MJ/m3]
Methane number
Algeria 43.38 55.00 75
Nigeria 43.32 55.39 75
Norway 42.58 54.68 78
Qatar 43.34 55.18 75
Trinidad and
Tobago
40.94 53.99 89
Table:2

MAJOR FINDINGS BASED ON QUALITY
OF FUEL
• Algeria have a better composition of natural gas than other
countries it has greater heating power for complete combustion.
• Wobbe number varies with specific gravity, flow velocity and
heating value of composition.
• Algeria, Nigeria, Qatar has a composition of fuel which have greater
resistance to knock. Methane number refers to the knock resistance.
Methane number of pure methane is 100.
10

RISK ANALYSIS OF LNG
11
1. Fire risk
• LNG is highly flammable and explosive substance having rapid flame
propagation, large mass burning rate about 2 times more than gasoline.
• Liquefied natural gas in the ships are stored at low temperature ( -
162°C) and atmospheric pressure. Liquid cargo of ultra-low temperature
contacting with general hull, because local cooling produces excessive
thermal stress, will make the hull brittle fractures spontaneously, and
loses ductility, thereby endangering the entire ship's structure.
• .Breakage in the combination of working pipeline and loading and
unloading system, rupture in liquid hold, collision and other factors may
lead to leakage of liquefied gas, which will result in fire accidents when
encountering fire.

12
2. Risk of vapour cloud explosion
• The boiling point of LNG (taking methane into account) is 162°C ,
easy to be gasified. Volume of gasified LNG in unit will increase 625
times.
• Once spherical tanks of liquefied natural gas in LNG ship leaks, initial
flash vaporization of the leaking liquefied natural gas occurs in the air.
• It generates lots of steam instantaneously, mixing with surrounding air
and then diluted and heated to form flammable gas cloud with air, and
reaching explosive concentrations (5% to15%), which will lead to vapour
cloud explosion when encountering fire.

13
3. Boiling liquid expanding vapour explosion (BLEVE)
• When liquefied natural gas spherical tanks on the ship are heated or exposed to
external flame for a long time, the intensity of spherical tanks will gradually
decreases.
• When the intensity decreases to a certain extent, the sphere will suddenly burst,
resulting pressure suddenly reduces, and liquefied natural gas vaporizes and burn
rapidly, resulting in boiling liquid expanding vapour explosion (BLEVE)
accidents.
• The energy of steam explosion derives from two sides. On the one hand,
liquefied natural gas sphere itself is a high-pressure container. On the other hand,
intense burning of liquefied natural gas can release enormous heat, resulting in a
huge fireball and strong thermal radiation.

14
4. Rapid Phase Transitions (RPT)
• Rapid Phase Transitions occur when the temperature difference between
a hot liquid and a cold liquid is sufficient to drive the cold liquid rapidly to
its superheat limit, resulting in spontaneous and explosive boiling of the
cold liquid.
• When a cryogenic liquid such as LNG is suddenly heated by contacting
a warm liquid such as water, explosive boiling of the LNG can occur,
resulting in localized overpressure releases. Energy releases equivalent to
several kilograms of high explosive have been observed.
• The impacts of this phenomenon will be localized near the spill source
and should not cause extensive structural damage.

15
5. Asphyxiation
• Methane is considered a simple asphyxiant, but has low toxicity to
humans.
• If a spill occurs and the vapour does not ignite, it would build to higher
concentrations. At higher concentrations, the vaporized methane will cause
an asphyxiation hazard to anyone exposed.
• If a spill or leak followed by a vaporization event were to occur in or
near water, then water in contact with the spilled LNG can accelerate the
vaporization process and increase the concentration of vapour in the
immediate area.

16
6. Cryogenic Burns and Structural Damage
• If LNG liquid contacts the skin, it can cause cryogenic burns.
• Potential degradation of the structural integrity of an LNG ship could
occur, because LNG can have a very damaging impact on the integrity of
many steels and common ship structural connections, such as welds.
• Both the ship itself and other LNG cargo tanks could be damaged from
a large spill.
7. Combustion and Thermal Damage
• LNG spill can result in thermal and pressure loading.
• Thermal loads are very dependent on the rate of energy conversion .
• Pressure loads are very dependent on the power density.
• The heat release rate per unit volume. Thus, how combustion occurs is
as important to the consequences of a spill as is the energy available.

17
8. LNG Fireballs
• Two types of combustion modes might produce damaging pressure:
‘deflagration’ and ‘detonation’.
• Deflagration is a rapid combustion that progresses through an unburned
fuel-air mixture at subsonic velocities.
• Detonation is an extremely rapid combustion that progresses through an
unburned fuel-air mixture at supersonic velocities.
• Ignition of a vapour cloud will cause the vapour to burn back to the spill
source. This is generally referred to as a ‘fireball’, which, by its nature,
generates relatively low pressures.
• It has a low potential for pressure damage to structures.

First LNG fuelled ship
18
Fig :2

PROPERTIES OF LNG
19
• LNG is simply natural gas that has been cooled to its liquid state at atmospheric
pressure at 260°F (-162.2°C) .
• Currently, imported LNG is commonly 95% – 97% methane, with the remainder a
combination of ethane, propane, and other heavier gases.
• LNG is transported at ambient pressures.
• LNG vapour, which reduces the gas into a practical size for transportation and
storage, reduces the volume that the gas occupies more than 600 times.
• LNG is considered a flammable liquid.
• LNG vapour is colourless, odourless, and non-toxic.
• LNG vapour typically appears as a visible white cloud, because its cold
temperature condenses water vapour present in the atmosphere.

ADVANTAGES
• Most likely improved revenue
• Increased number of passenger and crew cabins
• Improved environmental footprint
• Energy efficiency may be increased by installing flow-improving
• Additional public space and retail capacity
• Additional open deck spaces
• Reduction of main engine maintenance hours
• Less engine crew required
• Cheaper lubricants
• Cleaner engine room
• No soot on decks – less cleaning and wash water needed
• No need for exhaust cleaning devices or catalytic reactors
• Slightly lower noise level in engine room
20

DISADVANTAGES
• Design & retrofit cost compared to switching to distillates
• Time required for ship to be taken out of service for the retrofit
operations
• Bunkering challenges
• Statutory challenges
• LNG fuel cost pricing challenges
• LNG infrastructure challenges
• More tank space required to accommodate enough LNG to cover all
the itineraries
• Onshore bunkering logistics are still under development
• Rules still under development
• More sophisticated fuel equipment is required
21

CONCLUSION
• The risks connected with the use of LNG depend very much on its
state at the moment of release. If ignition does not occur at the
moment of release. Immediate ignition results in pool fires. Large
storage facilities should be provided with retention walls.
• The better fit of LNG fuel to shorter transport routes that enable
frequent fuelling.
• With proper safety regulations, LNG fuels offer significant local
pollution emissions advantages in the marine transport sector over
traditional marine petroleum fuels.
22

REFERENCE
1. Kamal Soundararajana, Eulalia Han, 2014, “ Probabilistic analysis
of marine fuels in emission controlled areas”,” International
Conference on Applied Energy, ICAE2014 “ , 1-s2.0-
S1876610214027842 (Energy Procedia), Volume 61, Pages 735–
738
2. L. VANDEBROEK , J. BERGHMANS , 17 October 2012 “Safety
aspects of the use of LNG for marine propulsion”, “ International
Symposium on Safety, Science and Technology”, 1-s2.0-
S1877705812031268 (Energy Procedia), Volume 45, Pages 21–
26.
23

• Jianhua Li, Zhenghua Huang, 2012, “Fire and explosion risk
analysis and evaluation for LNG ships ”,“ International Symposium
on Safety Science and Technology” 1-s2.0-S1877705812031359
(Energy Procedia), Volume 45,, Pages 70–76
• Alexey Mozgovoy, Frank Burmeister, Rolf Albus , 2015
“Contribution of LNG use for the low calorific natural gas
network’s safe and sustainable operation”, “3rd Trondheim Gas
Technology Conference, TGTC-3” 1-s2.0-S1876610215000120
(Energy Procedia), Volume 64, Pages 83–90.
24

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