Nmlc ef1 module 4

EXCELLENCE AND COMPETENCY TRAINING CENTER INC.
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NMLC-EF1-Module 4
Function 1:
Marine Engineering at the
Management Level
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NMLC-EF1-Module 4
COVERAGES:
Module 1 – Manage the operation of propulsion plant
machinery
Module 2 – Plan and schedule operations
Module 3 – Operation surveillance, performance
assessment and maintaining safety of propulsion plant
and auxiliary machinery
Module 4 – Manage fuel, lubrication and
ballast operations
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NMLC-EF1-Module 4
Function 1: Marine Engineering at the
Management Level
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Residual Fuels for the Marine Market
PROPERTIES OF MARINE FUELS
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Three types of Marine Fuels:
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❖ Distillate fuel – is composed of petroleum fractions of
crude oil that are separated in refinery by a boiling
process, called distillation.
❖ Residual fuel or residuum – is the fraction that did not
boil, sometimes referred to as “tar or Petroleum pitch”.
❖ Intermediate – is a mixture of these two basic type,
distillate and residual.
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DIESEL FUEL TYPES FOR MARINE USE
FUEL TYPE FUEL GRADES COMMON
INDUSTRY NAME
DISTILLATE DMX, DMA, DMB,
DMC
GAS OIL or MARINE
GAS OIL
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INTERMEDIATE
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IFO 180 - 380
MARINE DIESEL or
INTERMEDIATE FUEL
OIL ( IFO )
RESIDUAL RMA - RML FUEL OIL or
RESIDUAL FUEL OIL
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What is fuel oil testing (analysis)?
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• Fuel oil analysis is a series of tests used to determine the quality
of the marine fuel.
• The tests conducted determines the characteristics of the fuel
and is compared to the ISO 8217:1996 specification for marine
fuels.
• Results show whether the quality of a supplied fuel meets the
international standard of quality for the particular fuel
concerned.
• Test data can be analyzed and recommendations for onboard
treatment and fuel optimization can be made.
• Additional tests are also conducted to determine contaminants
or other substances have been added to the fuel.
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Why do we need fuel oil testing?
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➢ The main reason would be to provide invaluable information to
prevent engine damage or breakdowns caused by inferior quality
fuel.
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➢ Besides the possibility of poor maintenance, one of the major
reasons for engine breakdown is poor quality fuel.
➢ The fuel received by the ship may be of poor quality or even
contaminated fuel supplied through genuine mistakes or b y
rogue suppliers.
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Bad quality fuel is caused by:
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• dirt and sediments
• impurities in the fuel
• bacterial infestation
• presence of water
• presence of unknown additives
• presence of residual fuels
• unknown blending of various grades of fuels
• presence of contaminants
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Characteristics of Fuel
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Density and API Grade
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We need to know the density of the fuel for 2 Main Purposes:
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➢ First, we need the density figure to select the correct size of
gravity disc for use in the purifier and to determine the N e t
Specific Energy of the fuel.
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➢ Second, to know if we have paid for more fuel for more than
quality received. Fuel oil is brought and sold by weight (in metric
tons) we measure the quantity received in ships in tank received
by the supplier in terms in volume.
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Example, a bunker surveyor determines the quantity
received in a ship tank by the volume of the tank filled with fuel.
To obtain the weight of the fuel, we need the density to get the
weight of the fuel (volume X density = weight). This density figure
is usually declared by the supplier.
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Now, what if the actual density figured (by the lab test) is
lower than the declared value by the supplier? Theoretically, the
ship would have received less fuel given the volumetric
measurements being the same.
In such cases, you have paid for more fuel than was actually
delivered and operationally, your ship may not have enough fuel to
reach the next port.
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Viscosity
➢ The resistant of fluid to flow and is expressed by using a
kinematics viscosity at 50 oC with unit of (centistokes) cSt.
➢ The unit of redwood (No.10) second at 37.8 oC may be
used in some cases.
➢ We need to know the viscosity of the fuel to verify if we
have got the correct grade of fuel on board the ship. Did
we get a grade above ISO specification limits or paid for a
lower grade fuel but actually got a higher grade?
➢ We also need to know the viscosity value to determine
preheating and injection temperatures for our engine
settings.
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If the viscosity of heavy oil is used for Diesel engines is too high
or low, the following problems may occur:
1. Excessive Viscosity
- Suction of the pump worsens.
- Impurities are hard to separate.
- Without increasing an injection pressure, atomization worsens and
incomplete combustion takes place.
2. Inadequate Viscosity
- Fuel consumption rate increase due to the increased intakes from
various parts.
- Seizure or extra ordinary wear takes place due to the decrease in
lubricating action in an injection valve or the lapping section of a
fuel pump.
Even, if atomizing conditions are good during injection, penetration is
poor, which causes poor distribution and incomplete combustion.
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Water Content
1. Fuel with a high content of water will burn less efficiently.
This can lead to combustion problems and damaging fuel
injection equipment, cause corrosion and failure to exhaust
valves and turbochargers.
2. The net specific energy of the fuel is also affected by a high
water content in the fuel.
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Flash Point
➢ The temperature which indicates a probable danger of
inflammability.
➢ A flash point is defined to minimize fire risk during normal
storage and handling. We need to determine this figure to
meet safety and legal requirements.
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Sulphur
1. A common impurity, particularly in heavy fuels but also to an
increasing degree in heavy distillates from the cracking process.
2. Normally, the sulphur content in heavy fuels is in the range of
2.0% ~ 4.0% by weight.
3. Sulphur cannot be removed from the fuel by pretreatment and as
a consequence, will accompany the fuel into the cylinder and take
part in the combustion.
Sulphur has a number of negative effects on diesel engines:
▪ High sulphur content in the fuel will equate to a loss of fuel
efficiency.
▪ A danger for low temperature corrosion.
▪ A reduction in the fuel oils calorific value.
▪ A danger that it may act as a catalyst for fouling and high
temperature corrosion.
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Micro Carbon Residue
1. From (MCR) results, we can make predictions of incomplete
combustion and the possibility of carbon deposits forming.
2. The results enable us to take appropriate action to prevent the
possibility of injector nozzles becoming fouled.
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Total Sediment, Potential
➢ gives an indication of the cleanliness and stability of the fuel and
its tendency to form sludge which can result in clogging of fuel
lines and centrifuges.
➢ this test is performed to determine the potential of sediments
forming in the fuel.
➢ This test, we are able to take appropriate action to prevent fine
sediment particles entering the engine causing serious damage.
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Ash
1. level of ash content in the fuel enables us to detect possible
waste oil in the fuel.
2. steps preventing corrosion, deposits and excessive wear in
the engine by appropriate treatment with fuel additives.
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Aluminum and Silicon
➢ commonly known as Catalyst Fines, this test results indicate the
particles of spent aluminum and silicon catalyst in the fuel that
arises from catalytic cracking refinery process.
➢ By identifying its presence, we can prevent damage to the
engine fuel pumps, injectors, piston rings and cylinder liners.
➢ High Silicon content may also give us an indication of possible
sand or dirt in the fuel.
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Pour Point
1. determined to find out the lowest temperature at which the fuel
can be handled without excessive amounts of wax crystals forming
blocking the filters.
2. From the pour point result, storage and handling instructions can
be determined.
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Calorific Value (Specific Energy)
➢ is the amount of heat produced by unit quantity of oil when its
completely burned. This normally expressed in mJ/kg (BTU/lb).
Where: BTU/lb X 0.00232 = mJ/kg
➢ The calorific value of oil fuel is high being about 1 ½ times the
value of good coal or coke.
➢ When the calorific value of oil is determined the gross value is
obtained, representing the entire heat output of the combustion
but net values may be encountered in calculations.
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Characteristics of Fuel (Other Elements)
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Vanadium
➢ metal present in all crude oils in an oil-soluble form.
➢ also found in ash and has a corrosive effect.
➢ Vanadium in the presence of sodium will form various
corrosive ash complexes at varying stiction temperatures.
➢ This can result in high temperature corrosion on exhaust
components, turbocharger nozzles, super heaters and
economizer tubes.
➢ Avoid exhaust temperature in excess of 500 oC if possible.
➢ The use of magnesium- based ash modifier additives that
raise the stiction temperature considerably will help to
reduce long term accumulated corrosive ash damages.
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Characteristics of Fuel (Other Elements)
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Sodium
1. High Sodium presence is often a tell tale sign of sea water
presence in the fuel.
2. A high level of sodium will give rise to post-combustion deposits in
the turbocharger.
3. By determining the sodium level in the fuel, we can apply
appropriate treatment such as water washing to reduce its
harmful effects.
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Lead, Magnesium, Calcium and Zinc
➢ Lead, Magnesium, Calcium and Zinc contents in the fuel, detects
for the possibility of waste lube oils in the fuel.
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Iron and Nickel
➢ Testing for iron and nickel enables the detection of possible
catalysts in the fuel.
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Distillation Range
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Petroleum Products are any oil-based products which can be
obtained by distillation and are normally used outside the refining
industry.
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The exceptions to this are those finished products shows gross
refinery output for each product which is classified as refinery
feed stocks above.
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Distillation Range
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Aviation Gasoline
1. motor spirit prepared especially for aviation piston engines
2. octane number suited to the engine.
3. a freezing point of – 60 o C.
4. distillation range usually within the limits of 30 oC to 180 oC.
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Gas Diesel Oil (Distillate Fuel Oil)
➢ is obtained from the lowest fraction from atmospheric
distillation of crude oil, while heavy gas oil are obtained by
vacuum re-distillation of the residual from atmospheric
distillation.
➢ Gas / diesel oil distils between 180 oC and 380 oC.
➢ Several grades are available depending on uses; DO for
diesel compression ignition (cars, trucks, marine, etc.) light
heating oil for industrial and commercial uses,
➢ other gas oil including heavy gas oils which distil between
380 oC and 540 oC and which are used as petrochemical feed
stocks.
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Distillation Range
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Heavy Fuel Oil Residual
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1. this oils that make up the distillation residue.
2. comprises all residual fuel oils (including those obtained by
blending) its kinematics viscosity is above 10 cSt at 80 oC.
3. the flash point is always above 50 oC and the density is
always more than 900 kg/l.
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Kerosene
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➢ Comprises refined petroleum distillate intermediate in
volatility between gasoline and gas/diesel oil.
➢ It is medium oil distilling between 150 oC and 300 oC.
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Distillation Range
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Jet Fuel
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This category comprises both gasoline and kerosene type jet fuels
meeting specification for use in aviation turbine power units.
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1. Gasoline type jet fuel
➢ this include all light hydrocarbons oil for use in aviation
turbine power units.
➢ they distil between 100 oC and 250 oC.
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2. Kerosene type jet fuel
➢ this medium distillate used for aviation turbine power units.
➢ it has the same distillation characteristics and flash point as
kerosene (between 150 oC and 300 oC but not generally
above 250 oC).
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Distillation Range
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Liquefied Petroleum Gas (LPG)
1. these are the light hydrocarbons fraction of the paraffin series,
derived from refinery process, crude oil stabilization plants and
natural gas processing plants.
2. comprising propane (C3H8) and Butane (C4H10) or a
combination of the two.
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Motor Gasoline
➢ This light hydrocarbon oil for use in internal combustion
engines such as motor vehicles, excluding aircraft.
➢ Motor gasoline is distilled between 35 o C and 215 oC.
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Naphtha
➢ A feed stock destined for the petrochemical industry (e.g.
Ethylene manufacture or aromatics production).
➢ Naphtha comprises material in the 30 oC and 210 oC distillation
range or part of this range.
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Distillation Range
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Other petroleum products
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1. Industrial Spirit (SBP)
➢ light oils distilling between 30 oC and 200 oC, with a temperature
difference between 5% volume and 90% volume distillation point
losses of not more than 60 oC.
2. White Spirit
➢ Industrial spirit with a flash point above 30 oC.
➢ The distillation range of white spirit is 135 oC to 200 oC.
3. Lubricants
➢ are hydrocarbons produced from distillate or residue.
➢ they are mainly used to reduce friction between bearing surfaces.
4. Bitumen
➢ is often referred to as asphalt and is primary used for surfacing of
roads and for roofing materials.
➢ This category includes fluidized and cut back bitumen.
5. Paraffin waxes
➢ their main characteristics are as follows they are colorless,
odorless and translucent with a melting point above 45 oC.
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Distillation Range
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Other petroleum products
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Petroleum Coke
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1. Define as a black solid residue, obtained mainly by cracking
and carbonizing of residue feed stocks, tar and pitches in
processes such as delayed coking or fluid coking.
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Refinery Gas
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➢ Defined as non-condensable gas obtained during distillation
of crude oil or treatment oil products (e.g. cracking) in
refineries.
➢ It consists mainly of hydrogen, methane, ethane and
olefins.
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Cetane Number
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➢ is a measure of the ignition quality of a diesel fuel.
➢ is often mistaken as a measure of fuel quality.
➢ is actually a measure of a fuel’s ignition delay. This is the
time period between the start of injection and start of
combustion (ignition) of the fuel.
➢ In a particular engine, higher cetane fuels will have shorter
ignition delay periods than lower cetane fuels.
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❑ The performance of the diesel engine, whether it is burning a
distillate or residual, is dependent to ignition quality of the fuel.
❑ Optimization is achieved if ignition takes place at the top dead
center followed by smooth and rapid combustion which converts
the fuel into combustion products.
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Specification of Marine Fuel
British Standard BS MA 100
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1. applied to the fuel oil market and will contribute to a better
control of fuel quality obtained from the suppliers,
➢ offer security to the end user,
➢ has several limitations:
▪ It does not provide any advice about the important
heavy fuel properties such compatibility and sludge,
ignition properties and particle content.
▪ This means that these grades with extremely poor
ignition quality, a property not covered by the standard.
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Designation ISO-F-
Characteristics Test Method Limit DMX DMA DMB DMC
Density at 15°C, kg/m3 ISO 3675 or
ISO 12185
max. - 890 900 920
Kinematic Viscosity at 40°C, mm2/s (2) ISO 3104 min.
max.
1.40
5.50
1.50
6.00
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11.0
- 
14.0
Flash Point, °C ISO 2719 min. 43 60 60 60
Pour Point (Upper) (3) °C Winter
°C Summer
ISO 3016 max
max.
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-6
0
0
6
0
6
Cloud Point, °C ISO 3015 max. -16 (4) - - -
Sulphur, % (m/m) ISO 8754 max. 1.0 1.5 2.0 2.0
Cetane Number ISO 5165 min. 45 40 35 -
Carbon Residue (micro method 10% (V/V)
distillation bottoms) % (m/m)
Carbon Residue (micro method) % (m/m)
ISO 10370
 
ISO 10370
max
 
max
0.30
 
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0.30
 
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0.30
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2.50
Ash, % (m/m) ISO 6245 max. 0.01 0.01 0.01 0.05
Sediment, % (m/m) ISO 3735 max. - - 0.07 -
Total Existent Sediment, % (m/m) ISO 10307-1 max - - - 0.10
Water, % (v/v) ISO 3733 max. - - 0.3 0.3
Vanadium, mg/kg ISO 14597 max - - - 100
Aluminum plus Silicon, mg/kg ISO 10478 max. - - - 25
British Standard BS MA 100
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ISO 8217 “PETROLEUM PRODUCTS – FUEL (CLASS F)
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➢ This standard is based upon and has many similarities with
BS MA 100.
➢ It also has the same limitations as BS MA 100.
➢ The most important part of the standard is summarized into
levels giving limits for variety of fuel oil parameters for
distillates and heavy fuels.
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The main difference between the standards may be summed up as
follows:
ISO 8217 gives four distillates (DMX, DMA, DMB and DMC) where:
- DMX is for use in emergency generators,
- DMA is a gas oil
- DMB and DMC are Marine diesel oil.
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ISO 8217 “PETROLEUM PRODUCTS – FUEL (CLASS F)
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In connection with the specification of heavy fuel, it is important to
remember that the viscosity for oils currently on the market can
have four different reference temperatures and two different
measurement and two different measurement units, namely:
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1. seconds Redwood ( sRI ) at 100 oF
2. cSt at 50 oC
3. cSt at 80 oC ( after BS MA 100 )
4. cSt at 100 oC ( after ISO 8217 )
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It is very important when bunkering to obtain both the
measurement units and the reference temperature used to define
the viscosity of the supplied oil.
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CIMAC Requirements 1990 for Distillate Fuels for Diesel Engines
Characteristics Limit CIMAC DX CIMAC DA CIMAC DB CIMAC DC
Related to ISO 8217 Specification ISO-F DMX ISO-F DMA ISO-F DMB ISO-F DMC
Residual Inclusion None None Some Trace Allowed
Density at 15°C, kg/m³ Max. - 890 900 920
Kinematic Viscosity at 40°C, cSt (1) Max.
Min.
5.5
1.4
6.0
1.5
11
2.5
14
Flash Point, °C Min. 43 60 60 60
Pour Point °C Winter (5)
°C Summer
Max.
Max.
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-6
0
0
6
0
6
Cloud Point, °C Max. -16 - - -
Carbon Residue Ramsbottom on 10% res, % m/m
Microcarbon % m/m
Max.
Max.
0.20 0.20  
0.25
 
0.25
Ash, % (m/m) Max. 0.01 0.01 0.01 0.03
Sediment by Extraction, % (m/m) Max. - - 0.02 -
Total Sediment, % (m/m) Max. - - - 0.05
Water, % (v/v) Max. - - 0.30 0.30
Cetane Number (4) Min. 45 40 35 35
Visual Inspection Clear (3) Clear (3) May be Black May be Black
Sulphur, % (m/m) Max. 1.0 1.5 2.0 2.0
Vanadium, mg/kg Max. - - - 100
Aluminium plus Silicon, mg/kg Max. - - - 25
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CIMAC Requirements 1990 for Residual Fuels for Diesel Engines
CIMAC
Characteristics Limi
t
A 10 B 10 C 10 D 15 E 25 F 25 G 35 H 35 K 35 H 45 K 45 H 55 K 55
Related to ISO 8217:
1996
RMA
10
RMB
10
RMC
10
RMD
15
RME
25
RMF
25
RMG
35
RMH
35
RMK
35
RMH
45
RMK
45
RMH
55
-
Density at 15°C, kg/m³ Max 950 975 975 980 991 991 991 991 1010 991 1010 991 1010
Kinematic Viscosity at
100°C, cSt (1)
Max
m i n
(3)
10.0
6.0
10.0 10.0 15.0 25.0
15.0
25.0 35.0 35.0 35.0 45.0 45.0 55.0 55.0
Flash Point, °C min 60 60 60 60 60 60 60 60 60 60 60 60 60
Pour Point, °C
- Winter Quality
- Summer Quality
 
M a x
 
0
 
0
 
24
 
30
 
30
 
30
 
30
 
30
 
30
 
30
 
30
 
30
 
30
Carbon Residue, % m/m Max 12 12 14 14 15 20 18 22 22 22 22 22 22
Ash, % (m/m) Max 0.10 0.10 0.10 0.10 0.10 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15
Total Sediment After
Ageing, % (m/m)
Max 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
Water, % (v/v) Max 0.50 0.50 0.50 0.80 1.0 1.0 1.0 1.0 1..0 1.0 1.0 1.0 1.0
Sulphur, % (m/m) Max 3.5 3.5 3.5 4.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0
Vanadium, mg/kg Max 150 150 300 350 200 500 300 600 600 600 600 600 600
Aluminium plus Silicon,
mg/kg
                           Ignition Properties
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Storage and Heating Requirements of Fuel Oil
Settling Tanks - Water and other heavier impurities will precipitate
and can be drained away.
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Pre-treatment
General precaution for pre-treatment of heavy fuel oil, as to the
matter of details; refer to the handling manual of each equipment
and chemical additives provided in the ship.
➢ When purifying heavy fuel oil of high viscosity and high specific
gravity with the purifier, the passing fluid flow shall be properly
determined corresponding to respective properties of that oil.
➢ The oil of which the specific gravity is over 0.99 (15 °C/4 °C) is
hardly separable with the ordinary purifier. Therefore, the
enough cares shall be taken for treating the heavy fuel oil with
specific gravity near 0.991 (15 °C/4 °C).
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Pre-treatment
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➢ For better separating efficiency and the safety treatment of the
heavy fuel oil of high specific gravity and containing much
impurity, it is recommended to perform the two stage cleaning
with purifier and clarifier connected in series.
➢ The diesel oil is also to be purified.
➢ The additives for heavy fuel oil are sludge dispersive, oil
separator, and combustion accelerator the proper quantity of
additive to be used.
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Pre-treatment
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➢ If the sea water enters in the fuel oil, the emulsion will be
produced and oil/water separation becomes hard. Therefore,
the sea water should not be put in the fuel tank (double
bottom) as ballast. If the sea water is mixed with the fuel by
error, and emulsion breaker and separate water form fuel by the
purifier.
➢ The fuel oil strainer (with steam jacket) is to frequently cleaned
at the time of maiden voyage or just after the ship is out of the
dock.
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Purifier
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➢ It is used to separate two liquids and it provides with two
outlets the process liquid (oil/water mixture) flows through the
distributors to the space between conical discs.
➢ The water and solids particles move towards the periphery of
the bowl, where the solid particles are deposited on the inner
wall.
➢ The water leaves the bowl through the outlet.
➢ The oil moves the center of the bowl and the flow out through
the outlet.
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Separation Effect of the Centrifugal Purifier
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➢ For adjusting the plates in the centrifugal oil purifier, that
specified by the purifier manufacturers should be used in
accordance with specific gravity of the lube oil.
➢ The lubricating oils should be heated to 80 ~ 85 oC and sent to
the centrifugal oil purifier.
➢ Oil sent to the centrifugal oil purifier should be restricted to
about ½ its nominal capacity. And if the lubricating oil is
Heavy diesel, the water flushing should not be carried out
according to the oil standard, water flushing can be made but
the non-watering should be made at the final stage
!
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Storage General Recommendations and Legal Requirements
!
All industrial and commercial fuel oil listed have flash points
above 37.8 °C and are therefore not subject as regards storage
and handling to the Provisions of the Petroleum (Consolidation)
Act, 1928, which applies only to petroleum products such as
motor spirit which have flash points below 22.8 °C.
!
Fire insurance companies, the Fire Offices’ Committee and
some local authorities issue certain recommendations on storage
and handling of oil fuels for those using oil-burning equipment.
!
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!
Pipe Work
For pipe work operating at pressures up to 10.3 bar the following
materials should be used:
❖ Mild steel tubes and tubular fittings (non-galvanized): BS 1387.
❖ Malleable cast-iron pipe fittings: BS 143 and 1256.
❖ Wrought-iron pipe fittings: BS 1740
!
Materials
❖ The following materials should not be used where they may be
in contact with oil fuels:
❖ Yellow brass, including low-grade alloys of copper and zinc.
❖ Lead and zinc
❖ Galvanized metals, Natural rubber
!
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!
Storage Tanks Types
!
There are four main types of storage tank available:
❖ Mild steel welded,
❖ Mild steel sectional,
❖ Cast-iron sectional, and
❖ Reinforced concrete.
!
Of these four the mild steel welded tank is the most popular.
The majority of storage tanks are of the horizontal type, either
cylindrical or rectangular.
!
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!
Storage Tanks Capacities
!
❖ Each tank should have a separate filling pipe unless they are
situated next to each other, when a common filling point may
be used if both tanks take the same grade of fuel.
❖ Isolating valves should be incorporated to allow each tank to be
filled separately.
❖ Corresponding valves and tanks should be numbered for
identification.
❖ Where different grades of fuel are stored separately, individual
filling pipes must be fitted for each grade.
❖ Each filling pipe must carry a grade label at the filling point
clearly stating the grade of oil fuel for which it is intended.
!
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!
Storage Tanks Painting
!
❖ Storage tanks usually have all external surfaces painted with a
rust-inhibiting primer. These may be finished with a good
quality paint to suit the surrounding conditions.
❖ Internal surfaces do not require any further protection, except
larger vertical storage tanks with large areas of un-wetted
surface which may be given an oil resistant protective paint
coating.
!
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!
Storage Tank Fittings
!
Oil level indicators
!
❖ A brass dipstick is recommended as a cheap and reliable means
to determine the contents of a storage tank. A dipstick, when
required, is usually provided ready calibrated by the tank
manufacturer before the installation of the tank.
❖ In multi-tank installations, dipsticks should be identified with
the tank for which they have been calibrated. When a dipstick
is used in a tank storing residual oil fuels, care should be taken
to wipe the dipstick carefully before taking a reading.
!
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!
!
Draw-off Connection
❖ To isolate tank contents, a screw-down gate valve should be
fitted adjacent to the draw-off connection.
❖ Since stresses may be applied to valves during any tank
settlement or movement of pipe work, cast-Iron valves should
not be used for this purpose.
!
Drain Valve
❖ A screw-down gate valve of the same bore as the draw-off
connection should be fitted to every storage tank at its lowest
point to permit complete draining.
!
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!
!
Manhole
!
❖ Every storage tank must have a manhole in an accessible
position.
❖ It may be circular, oval or rectangular, and not less than 460
mm diameter if circular or 460 mm long and 410 mm wide if
oval or rectangular.
❖ The man lid must be securely fixed by bolts, studs or set-
screws, and have a liquid and vapor-tight joint. Close-woven
proofed asbestos, graphite on both sides, is a suitable jointing
compound.
!
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!
Heating
!
❖ The fuel oil shall be heated before supplied to the engine so that its
viscosity becomes in range of 13 ~ 18 cSt (60 ~ 80 sec. RW No.1)
at the inlet of the fuel injection pump. The heating temperature is
to be determined in accordance with 043-01 “Viscosity-Temp
Diagram of Fuel Oil ’’. However, the properties may differ by each
oil, so the heating is recommended to be effectuated in accordance
with the actually measured viscosity in the ship.
❖ Some of the heavy fuel oil produced sludge or other inconvenient
materials when heated long time at the temp. over 135 °C,
therefore, special cares shall be taken for the heater, filter, etc. in
which the fluid is easily staying on the way, when the high
temperature heating is required.
!
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❖ Low Grade of Fuel Oil
!
➢ If low grade of fuel oil are mixed, they are extremely difficult to
burn and injurious to the engine.
➢ This low grade fuel oil is difficult to identify as such from the
report on oil properties or specifications submitted by the
supplier at the time of bunkering.
➢ Most trouble some, hence deserving of specially careful
attention.
➢ Fuel oil produce using the fluid–catalytic–cracked residual as
stock because minute particles of silica alumina used as
catalyst in the fluid catalytic cracking persist to remain in the
oil and cause abnormal wear of the fuel injection pump, fuel
injection valve, cylinder liner, piston rings, etc.
!
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On Board Blending
!
When different fuel oils are mixed, the oil may produced much
sludge, especially, if the low grade fuel oil named as cracked oil is
mixed with other oil, it may cause more problems.
!
So, in case where the fuel oil mixed with different oil is used or
the tanks are used in common, the compatibility of fuel shall be
tested before use by heating oil up to the using zone.
!
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❖ General Precautions on Fuel Blending ratio
!
Blending Ratio should be set in reference to the results of
investigation of the following factors and the measures having
taken therefore.
➢ Whether or not there are engine constituent parts or their
related requiring replacement or modification when fuel is
changed from diesel oil to blended oil.
➢ Property of lubricating oil is used and method of handling.
➢ Load factor of engine and maintenance and servicing plan.
➢ Use of auxiliary fuel.
➢ Property of heavy fuel and diesel oil.
➢ Blended oil feed line must be equipped with heavy oil heaters so
that the viscosity of heavy oil at the inlet of the engine may be
adjusted properly.
!
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❖ Setting of Blending Ratio
!
➢ Blending ratio of the fuel oil should be set in reference to the
factors mentioned above.
➢ But the initial period of operation, it is recommended to
maximize the ratio of diesel as possible (lighter oil content
should be about 70% in the case of equipment of standard
specification ) and are having sufficient information on the
characteristics list of performance, increase the rate of heavier
oil gradually.
!
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❖ Necessary Factors to Determine the Blending Ratio
!
➢ Viscosity of heavy oil and diesel oil at the standard temp.
(normally 100° F ).
➢ Maximum tolerable temperature at engine inlet.
➢ Optimum viscosity blended oil to be supplied at engine inlet.
!
Method of Setting Blending Ratio
Conditions (assumption)
Viscosity of heavy oil : 1,500 sec. ( RW No.1, 100 F )
Viscosity of diesel oil : 40 sec. ( RW No.1, 100 F )
Max. Tolerance temp. at engine inlet : 80 oC
Optimum viscosity at engine inlet : 60 sec. (RW No.1)
!
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❖ Governing Law and Settlement of Disputes
!
Code of Practice for Bunkering by Barges/Tankers
!
This code was develop for the benefit of ship bunkering industry
comprising ship owners, operators, charterer's, bunker suppliers,
bunker tanker operators and surveyors.
!
With out proper documentation and verification during bunker
operation, disputes may arise. By carrying out bunker delivery
process systematically and carefully in accordance with the
requirements contained in this code, the likelihood of bunkering
disputes should be minimized. If however, a dispute should arise. This
Code should provide the technical basis for the resolution of the
disputes through negotiation, conciliation or arbitration.
!
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❖ Governing Law and Settlement of Disputes
!
Code of Practice for Bunkering by Barges/Tankers
!
In cases where arbitration is sought, Singapore International
Arbitration Center (SIAC), Maritime and Port Authority of
Singapore (MPA) and Singapore National Shipping Association
(SNSA) have drawn up a Bunkering deliveries. Ship/Owners/
buyers and bunker supplier are encouraged to incorporate an
arbitration clause into their contract for the supply of bunker in
order to facilitate the settlement of any disputes arising from
bunker deliveries.
It is however important to note this Code does not alter the
contractual obligations of ship owners/buyers and bunker
suppliers. In Singapore, MPA is the implementing authority of this
Code.
!
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❖ Selection of Fuel Grades
!
Bunker Specifications
!
➢ Bunker supplier shall, unless otherwise agreed by the buyer,
supply bunker of a quality which conform to or are better than
the specifications set by the International Organization for
Standardization (ISO) for “Petroleum Products – Fuels (Class F)
– Specification of Marine Fuels (ISO 8217 – latest edition).
!
➢ Ship owners/ buyers are advised to enter into agreed detailed
specifications in their contract with bunker suppliers. Ship
owners / buyers are reminded that if no detailed specification
are agreed, this may jeopardize any subsequent claims in the
event of dispute.
!
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❖ Bunker Requisition Form
➢ If more than one grade of bunker are to be supplied, the cargo officer
shall indicate on the form the order in which the grades are to be
supplied. To avoid contamination of product, normally a lighter grade
should be supplied first followed by a heavier grade, unless otherwise.
➢ The cargo officer shall confirm with the chief engineer the final
requirements of the vessel including the quantity, grade of bunker and
pumping rate required.
➢ All items in this form shall be completed.
➢ This completed form shall be signed by the cargo officer and the CE
with their names clearly printed. This form shall be endorsed with the
vessel‘s stamp and the bunker tanker’s stamp.
➢ Any cancellation or amendment on this form shall be signed by the
cargo officer and the Chief Engineer.
➢ At least two copies of this form are to be completed and signed. The
original shall retained by the bunker tanker and the duplicate shall be
given to the CE.
!
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❖ Tank Measurement/ Calculation Form
!
1. The Tank Measurement/Calculation Form is to record tank
gauging (or meter reading) and cargo temperature readings as
witnessed by the Chief Engineer.
2. This form shall contain the information as set out in Appendix C.
3. The cargo officer shall invite the chief engineer to witness the
opening gauge (or meter reading) and the taking of cargo
temperature of all cargo tanks of the bunker tanker.
4. If the chief engineer decline the invitation, the cargo officer shall
record this on the form and this shall be endorsed by the CE.
5. The tank gauging procedure shall be as set out in Appendix E.
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❖ Tank Measurement/ Calculation Form
!
6. If a flow meter is used instead of tank gauging, the flow meter
must be certified. The bunker Tanker shall carry a certificate of
verification issued by the Weight & Measures Office, Singapore.
The flow meter shall be calibrated at least once in every 12
months. The seal of the flow meter by the Weight & Measures
Office shall be intact.
7. All items in this form shall be completed
8. This completed form shall be signed by the cargo officer and the
CE with their Names, date and time of signing clearly printed.
This form shall be endorsed with the vessel‘s stamp and the
bunker’s stamp.
!
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Fuel Management Guidelines
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Sampling Requirements
!
1. All bunker tankers shall comply with the sampling requirements
as set out in Appendix F.
!
2. If the sampling requirements provided by the bunker tanker
differ from those as set in Appendix F, the Chief Engineer shall
make his comments in the Tank Measurement/Calculation form.
!
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Sampling Procedures
!
Request to Witness Sampling Procedures
!
➢ Invite the supplier’s representative to witness the sampling
procedures.
➢ If the supplier declines to attend the witnessing of sampling.
➢ It is important that you make an entry in the vessel’s log book
to record the refusal and events of the sampling and bunkering
procedures.
➢ In a litigation case, records made on a contemporaneous basis
(on the spot at time of occurrence) are very important.
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Sampling Procedures
!
How to take a Representative Sample
!
➢ To obtain a representative sample you should use a proper
sampling device and the sample should be taken by allowing a
continuous drip of the bunker to be collected through the whole
bunkering period.
➢ The sample should be taken in a clean and sealed container.
➢ The sample must be collected in a clean disposable container
such as cubitainer.
➢ Use a new cubitainer each time when you bunker to avoid
contamination of the sample from previous bunkers.
Contamination from cargo dust such as Bauxite dust or rain
water can occur if you see an open container.
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Sampling Procedures
!
Use a Continuous Drip Sampling Method
➢ The sampling should be through-out the whole duration of the
bunkering process, from start to finish.
➢ The needle valve on the samplers can be sealed with the
stainless steel cap provided to prevent tampering of drip flow
rates.
➢ It is too essential to have a crew member watch over the
sampling process, to prevent the sampling valve from being
tampered or shut off.
DO NOT take spot sample by just opening the sampling valve for a
short period in order to fill each sample bottle one at a time. This will
NOT be a valid sample and the test results will not reflect the quality of
bunker that was supplied to your ship.
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Responsibilities and Instructions
!
The CE or his representatives for bunkering procedures and the
bunkers on board. He must ensure the following:
!
➢ QUANTITY – Bunker tanks are sounded after arrival in port,
before and after special events (collision, grounding, etc.) for
standard reporting.
➢ BARGE – should be checked by gauges readings or if gauges
do not exist, by means of dips.
➢ SHORE Tanks - should be checked by gauges readings- or if
gauges readings or if gauges do not exist by means of dips.
➢ METERS – should be checked both before and after bunker
delivery.
!
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Governing Law and Settlement of Disputes
!
➢ This Contract shall be governed by and construed in accordance with
the United States Code and the Maritime Law of the United States,
and in accordance with the laws applicable. The proceedings shall be
conducted in accordance with the rules of the Society of Maritime
Arbitrators, Inc.
➢ These general terms and conditions' contain the entire agreement of
the parties with respect to the subject matter hereof and there are no
other promises, representations or warranties affecting it and shall not
be modified or amended in any way except in writing by the parties.
➢ For disputes where the total amount claimed by either party does not
exceed USD 20,000, the arbitration shall be conducted in accordance
with the shortened arbitration procedure of the Society of Maritime
Arbitrators, Inc.
!
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Guidelines for Accepting or Rejecting a Fuel Delivery
!
➢ ISO 4259:1992 provides for the systematic evaluation of the
validity of a given result and assumes that the sample being
analyzed is a ‘’representative’’ sample of the product
delivered/received.
➢ Clause 9 of ISO 4259:1992 further establishes a means for the
technical & statistical interpretation of ISO test method results.
➢ First, some ISO 4259 terminology. ISO 8217: 1996 tables 1 and
2 specify maximum and minimum limits to the true value of a
given property.
!
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4.Fuel Management Guidelines
Guidelines for Accepting or Rejecting a Fuel Delivery
!
Compatibility
Describes the tendency for precipitation to occur when one fuel oil is
mixed (blended) with another type of oil. Even though the original
fuel oil may be stable, it is still possible or precipitation to occur
when it is mixed with other oils. Heavy precipitation can lead to
overloading of pre-treatment system and in serious cases to the
blocking of the fuel supply to the engine.
!
Stability
Describes a fuel oil’s ability to keep heavy hydrocarbons in suspension
in the oil. Fuel oils with poor stability will produce sludge when
molecules coagulate and precipitate. High temperatures and
continues temperature variations increase tendency for sludge
formation. Heavy fuels that are applied for bunkers must be stable.
!
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Theory of Stability
Fuel Stability Testing
!
❖ The P-Value or Petpization Value test allows buyers and sellers of
residual fuel oil to determine the stability reserve of a finished fuel
product as well as help traders determine whether their product is
straight-run residue' or derived from cracked fuel oil.
❖ Two values are needed for this: P value and P0/ Frmax
 
The P-value of an oil provides information on: Stability and stability
reserve required for refinery process (thermal cracking) control
purposes. P0/Frmax value is required to predict whether the oil sample
can be blended with other products without stability problems.
 
This can be summarized as below:
P0 > Frmax : Fuel is stable
P0 < Frmax : Fuel is unstable
P0 = Frmax : Fuel is borderline
!
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Theory of Stability
Fuel Oil Test Definitions:
P-Value: Peptization of asphaltenes in asphaltene containing oil systems.
The critical cetane dilution is the number of millilitres of cetane
with which one gram of the sample can be diluted until it just
does not flocculate the asphaltenes.
P0: Defined as the peptizing power of the oil phase, or solubility
number of maltenes. It is expressed in units of Flocculation
Ratio (FR).
Frmax: Frmax expresses the maximum flocculation ratio obtainable at a
theoretical indefinite dilution. In simple words: it denotes the
minimal required peptizing power, needed by asphaltenes, to
just stay peptized.
!
P0/Frmax ratio: The ratio of P0 and Frmax is expressed as the P-ratio,
which in theory is equivalent to the P-value.
!
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Theory of Stability
Physical Structure of Fuel Oils
!
❖ Ignition Quality
The performance of a Diesel engine, whether it is burning a distillate
or residual fuel, is dependent on the ignition quality of the fuel.
Optimization is achieved if ignition takes place at top dead center
followed by smooth and rapid combustion which converts the fuel
into gaseous combustion products.
!
❖ Cetane Number
It is a measure of the ignition quality of a diesel fuel. It is often
mistaken as a measure of fuel quality. Cetane number is actually a
measure of a fuel’s ignition delay. This is the time period between
the start of combustion (ignition) of the fuel. In a particular diesel
engine, higher cetane fuels will have shorter ignition delay periods
than lower cetane fuels.
!
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Theory of Stability
!
How does Cetane Number Affect Engine Operation?
!
There is no benefit to using a higher Cetane Number fuel than is
specified by the engine’s manufacturer. The ASTM Standard
Specification for Diesel Fuels (D-975) states that the Cetane no.
requirements depend on:
- Engine design
- Engine size
- Nature of speed
- Load variations
- Starting and atmospheric conditions.
Increase in cetane number over values actually required does
not materially improve engine performance.
!
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Theory of Stability
!
Diesel Fuel with Cetane number lower than the minimum
requirements can cause:
!
1. rough engine performance.
2. more difficult to start, especially in cold weather or at high
altitudes.
3. accelerate lube oil sludge formation.
4. increase engine deposits resulting in more smoke.
5. increased exhaust emissions. greater engine wear.
!
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Theory of Stability
!
Diesel Fuel which meet Cetane number engine operating
requirements:
!
1. will improved engine cold starting
2. reduce smoke during stat-up
3. improve fuel economy
4. reduce exhaust emissions
5. improve engine durability
6. reduce noise and vibration
!
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Theory of Stability
!
1. Total Base Number (TBN)
1. It is the measure of the alkaline reserve, or the ability of
the oil to neutralize acids from combustion.
2. Severe depletion of the TBN results in acid corrosion and
fouling within the engine.
3. Maintaining a correct alkaline reserve is critical in
preventing unnecessary corrosion of the upper piston,
piston rings and top end bearing. Additionally, Low TBN is
indicative of reduced oil detergency.
Low TBN will cause:
➢ corrosion of combustion space and bearings
➢ fouling within the engine
!
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Theory of Stability
!
The exact composition of petroleum products varies depending:
➢ sources of crude oil (crude oil is derived from underground
reservoirs which vary greatly in the chemical composition).
➢ the refining practices used to produce the product.
!
Asphaltenes
➢ The color of resid/bunker fuel is always black, dark brown
or at least very dark.
➢ This color arises from the asphaltenes in the crude oil.
➢ They are very large molecules containing carbon, hydrogen,
oxygen, sulfur and some nitrogen.
➢ They are completely insoluble in oil. However, they are
stabilized in the oil by molecules called maltenes.
!
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Theory of Stability
!
Maltenes
!
1. The maltenes are attached to the asphaltenes though
various bonding mechanisms.
2. When crude oil is pumped from the ground, there is delicate
balance between the asphaltenes and maltenes.
3. This balance causes the asphaltenes to appear stable and
soluble in the oil.
4. As various process are carried out on petroleum to transport
it, refine it and store it, this balance is often changed causing
asphaltenes to no longer stabilized by the maltenes.
5. This change in stability can cause the asphaltenes to
precipitate and coagulate from the fuels.
!
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Theory of Stability
!
➢ Because asphaltenes and maltenes are very large, complex
molecules, they have high boiling points and carry into therein.
➢ Since most asphaltenes end up in the “ heavy oil”, these oils
are very often intensely black and similarly, since the
asphaltenes don’t distill into other petroleum fractions,
distillates are normally light in color.
➢ Asphaltenes when separated from fuels are shiny black solids
and are very hard.
➢ The common definition of asphaltene it is insoluble in aliphatic
solvents, but very soluble in aromatic solvents.
➢ The common test for asphaltenes, IP 148, takes advantage of
this property to determine asphaltenes in petroleum fractions.
!
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Theory of Stability
Causes and Mechanisms of Instability
!
Improved Stability of Hydrocarbons Containing Asphaltenes
➢ Field of Invention: The stability of heavy fuel oils obtained from
thermally cracked residual oils is a well known problem with significant
economic ramifications.
➢ Residual fuel oil consists predominantly of an oil phase, the
composition of which is almost entirely related to the crude oil from
which it originates.
➢ In this oil phase are dispersed relatively large hydrocarbon molecules
called asphaltenes. It is the nature of asphaltenes to be attracted to
one another, and it is this tendency, along with size and concentration
of the asphaltene molecules, that are consequences of both the crude
oil type and the thermal cracking manufacturing process. The
compositions of the various thermally cracked residual fuel oils can
thus vary widely.
!
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Theory of Stability
Causes and Mechanisms of Instability
!
➢ The stability of a residual fuel oil can be defined as its ability to
resist the formation of carbonaceous sludge during storage and
handling.
➢ The effects of sludge formation in a residual fuel oil in systems
where that fuel oil is used to power an engine can result in
choked centrifuges, filter blocking, heater fouling, and
ultimately, engine shut down and damage.
➢ The simple formation of sediment over time in the bottom of
storage tanks causes problems because these sludge layers are
difficult to remove. These sediments are due to the aggregation
of the unstable, high molecular weight polynuclear aromatic
asphaltenes.
!
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Theory of Stability
The traditional approaches of trying to stabilize thermally cracked
fuel oils:
!
➢ is to blend them with valuable refinery stocks or add any one of
a variety of different chemicals to the fuel oils stored in tanks.
➢ However, these techniques have the disadvantage of having to
be customized for each particular fuel oil.
➢ Moreover blending of fuel oil with other refinery cutter stocks
requires the availability of aromatic heavy boiling cuts from Fluid
Catalytic Cracking plants.
➢ If such streams are not available, any attempt to blend unstable
cracked fuel with atmospheric or vacuum gas-oil will result in a
de-stabilization of asphaltenes. Addition of chemicals in storage
tanks also requires good mixing, which is seldom available.
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Theory of Stability
Manufacturing Consideration
Refining Process on various chemical elements and their
corresponding percentages.
!
Refining of Petroleum
➢ Petroleum is a complex mixture of organic liquids called crude oil
and natural gas, which occurs naturally in the ground and was
formed millions of years ago.
➢ Crude oil varies from oilfield to oilfield in color and composition,
from a pale yellow low viscosity liquid to heavy black 'treacle'
consistencies.
➢ Crude oil and natural gas are extracted from the ground, on land
or under the oceans, by sinking an oil well and are then
transported by pipeline and/or ship to refineries where their
components are processed into refined products.

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Theory of Stability
Refining of Petroleum
➢ Crude oil and natural gas are of little use in their raw state; their
value lies in what is created from them: fuels, lubricating oils,
waxes, asphalt, petrochemicals and pipeline quality natural gas.
➢ As crude oil comes from the well it contains a mixture of
hydrocarbon compounds and relatively small quantities of other
materials such as oxygen, nitrogen, sulphur, salt and water.
➢ In the refinery, most of these non-hydrocarbon substances are
removed and the oil is broken down into its various components,
and blended into useful products.
➢ Natural gas from the well, while principally methane, contains
quantities of other hydrocarbons - ethane, propane, butane,
pentane and also carbon dioxide and water. These components
are separated from the methane at a gas fractionation plant.
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Theory of Stability
Petroleum Consists of Three Main Hydrocarbon Groups:
!
❖ Paraffin
!
➢ These consist of straight or branched carbon rings saturated
with hydrogen atoms, the simplest of which is methane (CH4)
the main ingredient of natural gas.
➢ In this group includes ethane (C2H6), and propane (C3H8).
!
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Theory of Stability
Petroleum Consists of Three Main Hydrocarbon Groups:
!
❖ Hydrocarbons
!
➢ With very few carbon atoms (C1 to C4) are light in density and
are gases under normal atmospheric pressure. Chemically
paraffin are very stable compounds.
!
❖ Naphthene
!
➢ Naphthenes consist of carbon rings, sometimes with side chains,
saturated with hydrogen atoms.
➢ Naphthenes are chemically stable, they occur naturally in crude
oil and have properties similar to paraffin.
!
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Theory of Stability
Aromatics
➢ Aromatic hydrocarbons are compounds that contain a ring of six
carbon atoms with alternating double and single bonds and six
attached hydrogen atoms.
➢ This type of structure is known as a benzene ring.
➢ They occur naturally in crude oil, and can also be created by the
refining process.
➢ The more carbon atoms a hydrocarbon molecule has, the
"heavier" it is (the higher is its molecular weight) and the
higher is its the boiling point.
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Theory of Stability
The Refining Process
➢ Every refinery begins with the separation of crude oil into
different fractions by distillation.
➢ The fractions are further treated to convert them into mixtures
of more useful products by various methods such as cracking,
reforming, alkylation, polymerization and isomerisation.
➢ These mixtures of new compounds are then separated using
methods such as fractionation and solvent extraction.
Impurities are removed by various methods, e.g. Dehydration,
desalting, sulphur removal and hydro treating.
➢ Refinery processes have developed in response to changing
market demands for certain products. With the advent of the
internal combustion engine the main task of refineries became
the production of petrol.
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Theory of Stability
The Refining Process
!
➢ The quantities of petrol available from distillation alone was
insufficient to satisfy consumer demand.
➢ Refineries began to look for ways to produce more and better
quality petrol.
!
Two types of processes have been developed:
- Breaking down large, heavy hydrocarbon molecules
- Reshaping or rebuilding hydrocarbon molecules.
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Theory of Stability
Distillation (Fractionation)
Because crude oil is a mixture of hydrocarbons with different
boiling temperatures, it can be separated by distillation into groups of
hydrocarbons that boil between two specified boiling points.
Two types of distillation are performed: atmospheric and vacuum.
!
❖ Atmospheric Distillation
➢ Takes place in a distilling column at or near atmospheric pressure.
➢ The crude oil is heated to 350 – 400 oC and the vapor and liquid
are piped into the distilling column.
➢ The liquid falls to the bottom and the vapor rises, passing through
a series of perforated trays (Sieve Trays).
➢ Heavier hydrocarbons condense more quickly and settle on lower
trays and lighter hydrocarbons remain as a vapor longer and
condense on higher trays.
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Theory of Stability
➢ To recover additional heavy distillates from this residue, it may
be piped to a second distillation column where the process is
repeated under vacuum, called Vacuum Distillation.
➢ This allows heavy hydrocarbons with boiling points of 450 oC
and higher to be separated without them partly cracking into
unwanted products such as coke and gas.
➢ The heavy distillates recovered by vacuum distillation can be
converted into lubricating oils by a variety of processes.
➢ The most common of these is called Solvent Extraction.
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Theory of Stability
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Theory of Stability
Reforming
!
➢ Process which uses heat, pressure and a catalyst (usually
containing platinum) to bring about chemical reactions which
upgrade naphtha into high octane petrol and petrochemical
feedstock.
➢ The naphtha are hydrocarbon mixtures containing many paraffin
and naphthenes. In Australia, this naphtha feedstock comes from
the crude oil distillation or catalytic cracking processes, but
overseas it also comes from thermal cracking and hydro-cracking
processes.
➢ Reforming converts a portion of these compounds to isoparaffins
and aromatics, which are used to blend higher octane petrol.
Paraffin are converted to isoparaffins
Paraffin are converted to naphthenes
Naphthenes are converted to aromatics
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Theory of Stability
Cracking
Cracking processes break down heavier hydrocarbon molecules (high
boiling point oils) into lighter products such as petrol and diesel. These
processes include catalytic cracking, thermal cracking and hydro-
cracking.
!
❖ Catalytic Cracking
➢ used to convert heavy hydrocarbon fractions obtained by vacuum
distillation into a mixture of more useful products such as petrol
and light fuel oil.
➢ In this process, the feedstock undergoes a chemical breakdown,
under controlled heat (450 - 500o C) and pressure, in the presence
of a catalyst - a substance which promotes the reaction without
itself being chemically changed. Small pellets of silica - alumina or
silica - magnesia have proved to be the most effective catalysts.
!
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Theory of Stability
Fluid Catalytic Cracking
!
➢ uses a catalyst in the form of a very fine powder which flows
like a liquid when agitated by steam, air or vapor.
➢ the catalyst is usually a mixture of aluminum oxide and silica.
➢ the introduction of synthetic zeolite catalysts has allowed much
shorter reaction times and improved yields and octane numbers
of the cracked gasoline's.
!
Thermal Cracking
!
➢ uses heat to break down the residue from vacuum distillation.
➢ the lighter elements produced from this process can be made
into distillate fuels and petrol.
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Theory of Stability
Hydro-cracking
!
➢ can increase the yield of petrol components, as well as being
used to produce light distillates.
➢ it produces no residues, only light oils.
➢ is catalytic cracking in the presence of hydrogen.
➢ the extra hydrogen saturates, or hydrogenates, the chemical
bonds of the cracked hydrocarbons and creates isomers with
the desired characteristics.
➢ is also a treating process, because the hydrogen combines with
contaminants such as sulphur and nitrogen, allowing them to
be removed.
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Theory of Stability
Alkylation's
➢ Alkylation refers to the chemical bonding of these light
molecules with isobutene to form larger branched-chain
molecules (isoparaffins) that make high octane petrol.
!
Isomerisation
➢ refers to chemical rearrangement of straight-chain hydrocarbons
(paraffin), so that they contain branches attached to the main
chain (isoparaffins).
➢ This is done for two reasons:
- They create extra isobutene feed for alkylation.
- They improve the octane of straight run pentanes and
hexanes and hence make them into better petrol
blending components.
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Theory of Stability
Polymerization
!
➢ Under pressure and temperature, over an acidic catalyst, light
unsaturated hydrocarbon molecules react and combine with
each other to form larger hydrocarbon molecules.
➢ Such process can be used to react butanes (olefin molecules
with four carbon atoms) with iso-butane (branched paraffin
molecules, or isoparaffins, with four carbon atoms) to obtain a
high octane olefinic petrol blending component called polymer
gasoline.
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Theory of Stability
Hydro treating
➢ Hydro treating is one way of removing many of the
contaminants from many of the intermediate or final products.
➢ In the process, the entering feedstock is mixed with hydrogen
and heated to 300 – 380 oC.
➢ The oil combined with the hydrogen then enters a reactor
loaded with a catalyst which promotes several reactions:
1. Hydrogen combines with sulphur to form hydrogen sulphide
(H2S).
▪ Nitrogen compounds are converted to ammonia.
▪ Any metals contained in the oil are deposited on the catalyst.
▪ Some of the olefins, aromatics or naphthenes become
saturated with hydrogen to become paraffin's and some
cracking takes place, causing the creation of some methane,
ethane, propane and butanes.
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Theory of Stability
Sulphur Recovery Plants
!
The hydrogen sulphide created from hydro treating is a toxic gas
that needs further treatment.
!
The usual process involves two steps:
1. The removal of the hydrogen sulphide gas from the
hydrocarbon stream.
2. The conversion of hydrogen sulphide to elemental sulphur, a
non-toxic and useful chemical.
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Theory of Stability
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Theory of Stability
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Theory of Stability
Storage Stability
!
Effective on board fuel management is critical in maintaining adequate
quality.
➢The primary concerns are particulates, water, and microbiological
contamination. Particulate contamination can be caused by dirt, rust
flakes, catalyst fines, or other foreign matter introduced into the
fuel. It can be introduced from a fuel source, or from the ship’s own
storage tanks and piping. Particulates generally settle out of solution
and accumulate at the bottom of storage tanks.
➢ However biological contamination and storage stability problems
also generate particulates that can stay in suspension. Particulate
contamination will clog fuel oil filters, and can potentially damage
fuel injection equipment. Timely and periodic tank stripping is the
best means to keep particulate contamination manageable.
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Theory of Stability
Thermal Stability
!
➢ A measure of fuel degradation, unstable fuels will turn dark,
produce gum residue and result in plugged filters and poor
performance.
➢ It would appear that deposit formation occurring primary as
result of thermal instability of the fuel with storage instability
also entering into this problem.
➢ Fuel tested using ASTM D6468 (Test Method for High Temp.
Stability of Distillate Fuels).
➢ Additives/Inhibitors contains stabilizer that help maintain or
improve the stability of the fuels and help to prevent deposit
formation.
!
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4.3 Theory of Stability
Storage Resulting from Wax Separation
!
➢ Long-term storage of crude oils, essential to maintain
adequate supplies in the event of future shortages, results
in deterioration of the crude oil caused by air oxidation,
photo oxidation, and condensation.
➢ Deterioration forms polymeric polar substances that stay
solid at room temperature.
➢ The substances precipitate from the main body of the crude
oil with other components to form sludge’s which are
difficult to transfer from storage. As a result, a significant
amount of valuable resource can be lost during storage.
!
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Theory of Stability
Effect of Temperature Cycles
!
Sulphur Oxides (Sox)
1. Sulphur from the fuel is oxidized to sulphur dioxide then to
sulphur trioxide, with the presence of water vapor in the flue
gas, sulphuric acid is formed.
➢ Sulphur content in bunker received considerable public
attention because of environmental concerns such as acid rain.
➢ In 1997, IMO members signed a treaty limiting the sulphur
content in residual fuel to 4.5%m/m.
➢ Annex VI of Marpol 73/78 will be enforced on 19 May 2005.
➢ In regional emission control areas is further limited to
1.5%m/m.
➢ High level of sulphur combined with reduced load, low
temperature and moist scavenge air, can cause severe
corrosion of engine parts.
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Theory of Stability
!
❖ Nitrogen Oxides (NOx)
!
➢ Several air polluting gasses composed of Nitrogen and
oxygen which play an important role in the formation of
photochemical smog.
➢ Nitrogen Oxides are collectively referred to as “NOx” where
“x” represents a changing proportion of oxygen to nitrogen.
Internal combustion engines are significant contributors to
the worldwide nitrogen oxide (NO) and the reddish- brown,
very toxic and reactive nitrogen oxides (NO2).
➢ Other nitrogen oxides, such as Nitrous oxide N2O
(anesthetic “laughing gas”) are not regulated emissions.
!
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Theory of Stability
!
❖ Cold End Corrosion
!
➢ The temperature at which Sulphuric first condenses occurs
from (116-166 °C) or higher depending on sulphur trioxide
concentrations in the flue gases.
➢ The dew point is dependent on the concentration of sulphur
trioxide and water vapor in the flue gases and will vary with
the concentration of the SO3.
➢ Cold end corrosion will occur wherever the temperature of
the metal surface drops below the sulphuric acid dew point
and the acid settles on the metal surface.
!
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Compatibility
Asphaltenes
➢ It is based on the solution properties of petroleum residua in
various solvents.
➢ This generalized concept has been extended to fractions
derived from other carbonaceous sources, such as coal and oil
shale.
➢ With this extension, there has been much effort to define
Asphaltenes in terms of chemical structure and elemental
analysis as well as by the carbonaceous source.
➢ There are petroleum Asphaltenes, coal tar Asphaltenes, shale
oil Asphaltenes, tar sands bitumen Asphaltenes, and so on.
➢ The concept of Asphaltenes is rooted in the solubility behavior
of high boiling hydro-carbonaceous materials in benzene and
low molecular weight n-paraffin hydrocarbons.
➢ This behavior is a result of physical chemistry effects which are
due to a spectrum of chemical properties.
!
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Compatibility
Maltenes
➢ Derived from Utah bitumen were separated by gel
permeation chromatography (GPC) into fractions having
number average molecular weights (MW) in the range from
300 to 11985.
➢ The fractions were examined by vapor pressure osmometry,
absorption spectrometry in the visible region as well as
proton and carbon-13 NMR.
➢ The results are reported in comparison with those for the
corresponding fractions separated from Athabasc maltenes.
Utah fractions appeared to be more aliphatic with longer
average aliphatic chains lengths.
➢ Branched and alicyclic types were more abundant in Utah
samples, especially those with low MW.
!
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Compatibility
Residual Fuel Compatibility
1. In recent years there has been an increased use of low quality
crude in refinery feedstock's.
2. This results from several factors including the:
- depletion of light,
- sweet domestic crude oils, and
- the growing dependence upon heavy, sour crude’s
from both domestic and foreign sources.
Refiners have found it necessary to increase the
conversion of residue to distillate fuels which has
resulted in increased problems in product quality.
!
3. Experience has shown that conventional fuel oil analyses are
inadequate to allow prevention or prediction of handling
problems resulting from fuel instability or incompatibility of fuel
mixtures.
!
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Compatibility
Residual Fuel Compatibility
!
➢ A number of `problem’ and `non-problem’ fuels supplied by
utilities were analyzed in an attempt to understand the
reasons for the reported problems.
➢ These fuels were carefully characterized by the
determination of chemical and physical properties.
➢ It was apparent, however, that a baseline or reference test
was needed to categorize the fuels as `problem’ and `non-
problem’.
➢ Supplemental samples were obtained through the
cooperation of participating utilities, and these and initial
samples were subjected to baseline tests for determining
stability and compatibility characteristics.
!
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Compatibility
➢ These baseline tests were the basis for the evaluation of
rapid tests which might be useful for the prediction of
potential problems.
➢ Some of the simple techniques which were evaluated for
usefulness in predicting instability or incompatibility potential
included:
- determination of sediment by hot filtration (existent dry
sludge),
- determination of potential dry sludge (Shell accelerated
stability test),
- determination of coke content,
- a modified spot test and
- prediction of incompatibility between fuels through the
use of the Bureau of Mines correlation Index and toluene
equivalence.
!
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Compatibility
Formation of Sludge from Wax Separation
!
Long-term storage of crude oils, essential to maintain
adequate supplies in the event of future shortages, results in
deterioration of the crude oil caused by air oxidation, photo
oxidation, and condensation. Deterioration forms polymeric
polar substances that stay solid at room temperature.
!
The substances precipitate from the main body of the crude
oil with other components to form sludge’s which are difficult
to transfer from storage. As a result, a significant amount of
valuable resource can be lost during storage.
!
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Compatibility
Formation of Sludge from Wax Separation
!
Some of the mechanisms that form sludge have been
previously reported, and are summarized as:
• Separation and precipitation of the Asphaltenes fraction;
• Separation and precipitation of the wax fraction;
• Oxidative polymerization and precipitation of heteroatom
(oxygen, sulfur, and nitrogen) containing compounds;
• Agglomeration and precipitation of inorganic contaminants.
!
Studies were conducted on several crude oils to determine the
organic components in various sludge’s, and the chemical
structure of the components. The solubility decrease of crude
oil components caused by micelle formation (an oriented
arrangement of a number of molecules where there are few or
no unshared electron pairs).
!
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Compatibility
Water Shredding
1. Fuel expenditures now a days have risen to make up more
than a third of a vessel’s operating costs.
2. Optimizing fuel combustion and thereby reducing fuel
consumption has therefore become main issue.
➢ To achieve this aim, fuel conditioning must take place.
!
Shredding the fuel especially the large aspalthene clusters into
micro-sized particles (Approx.5 microns of size) bring two major
advantages:
- Reducing sludge output
- Improving combustion
FUEL SHREDDER helps saving significant cost, both in maintenance
as well as in operation. Furthermore, it allows homogenization with
injected fresh water which in the ends leads to lower nitrous oxide
(NOx) emissions.
!
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Compatibility
Fuel Blending
➢ A stable fuel emulsion comprising water, coal and an oil
component comprising a distillate oil and residual oil
stabilizing ingredient.
➢ The stable fuel is produced by:
- forming water/coal slurry,
- blending the distillate oil and
- stabilizing residual oil together, combining the
slurry and oil blend and agitating the mixture.
➢ A stable fuel emulsion comprising essentially only water and
oil wherein the oil is comprised of a distillate oil component
and a residual oil stabilizing ingredient.
➢ The stable fuel is produced by blending the distillate oil and
the stabilizing residual oil together, combining the resulting
blend with water and agitating the mixture
!
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Compatibility
Fuel Blending
!
Useful Rules of Thumb in Mixing Heavy Fuel Oil
!
➢ When different fuel oils are mixed, the oil may produce much
sludge, especially, if the low grade of fuel oil named as
cracked oil is mixed with other oil it may causes more
problems.
!
➢ So in case where the fuel oil mixed with different oil is used
or the tanks are used in common, the compatibility of the
fuel shall be tested before use by heating oil up to the using
zone.
!
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Density/Volume/Weight Relationship
➢ Bunker is sold by Weight, but delivered by Volume. The
Density is used to calculate the weight of bunkers delivered.
➢ The potential financial loss to a ship owner from an over
declared bunker receipt can be very substantial.
!
Example: Volume X Density = Weight
!
A ship owner purchases 3,000MT of 180 cSt fuel at a price of
USD 158/MT. The bunker receipt showed a Density of 0.9888
gm/ml. Maritec tested density was 0.9576 gm /ml. This would
have resulted in an overpayment of USD 15,010.00 if the
density had not been tested.
!
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We need to know the density of the fuel for 2 Main purposes:
1. To select the correct size of gravity disc for use in purifier and to
determine the Net Specific Energy of the fuel.
➢ To know if we have paid for more fuel than actually received in a
ship’s tank by the volume of the tank filled with fuel. The ship
would received less fuel given the volumetric measurements
being the same. In such cases, you have paid more fuel than
was actually delivered and operationally, your ship may not have
enough fuel to reach to the next port.
VOLUME (m3) DENSITY @ 15°C WEIGHT (MT)
Bunker Receipt Data 3,034 m3 0.9888 3,000 MT
Maritec Lab. Result 3,034 m3 0.9576 2,905 MT
Short Delivered Weight (MT) - 95 MT
Loss in USD with Bunker Price @ 158/MT - 15,010 $
!
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Petroleum Measurement Tables
!
Use of Volume Correction Coefficient
➢ Due to Thermal expansion and contraction of petroleum
products, are all purchased and sold based on a volume at
60 °F.
➢ Therefore, all petroleum products are corrected to this
temperature by using a correction factor.
➢ This factor converts quantities of oil at different temperature
at a comparable volume at a standard temperature.
!
When Mechanical flow meters or differential pressure type flow
elements are used for invoicing or efficiency calculations, the
reading must be temperature compensated to provide an accurate
reading.
!
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!
Use of Volume Correction Coefficient
➢ To convert gross gallons at the loading and unloading
temperature to net gallons at 60°F, the temperature, the
API Gravity of the oil and the coefficient of expansion
factor must be known.
➢ A rough approximation of net gallons can be obtained from
the equation provided.
➢ For a more precise conversion consult the factory or the
Manual of Petroleum Measurement Standards jointly
issued by the American Society for Testing and Materials,
the American Petroleum Institute and the Institute of
Petroleum.
!
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!
Rough Approximation Method
Correction Factor = 1 – ( ΔT X Multiplier)
Oil API Multiplier
0 to 14.9 0.00035
15 to 34.9 0.0004
35 to 50.9 0.0005
Example:
Oil having 17 API is clocked through a positive displacement meter
at 565 GPH. The oil is 190 °F at the meter. Find the corrected (i.e.
60 °F) volumetric flow.
= 190 – 60 = 130 T
Correction Factor = 1 – (130 X 0.0004) = 0.9480
Corrected Volumetric Flow = 565 X 0.9480 = 535.62 GPH
!
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!
Energy required to Heat #6 Oil
Electric:
Watts = 1.25 X GPH X ΔΤ (F)
Amps (single phase) = watts/volts
Amps (three phase) = watts/(volts X 1.73)
Example: To heat 600 GPH of #6 oil from 90 °F (32 °C) to 150 °F
(65.5 °C)
ΔΤ = 60°F (15.5°C)
Watts = 1.25 X 600 X 60 = 45,000 watts
KW = 45
Amps at 460/3/60 = 56.5
!
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!
Steam
!
Lbs/hr steam = (lbs/hr oil X ΔT) / 1920 (#6 oil & 5 psi steam
Lbs/hr steam = (gph X lb/gal X ΔΤ) / 1920
!
Example: To heat 600 GPH of #6 oil from 90 °F (32 °C) to 150 °F
(65.5 °C)
!
Lbs / hr steam = (600 X 8 X 60) / 1920 = 150
!
!
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!
!
NMLC-EF1-Module 4
126
Combustion of Fuel
Different Stages of Combustion
!
❖ Volatile release
!
➢ After injection, fractional distillation occurs as the fuel
droplets are heated in hot air or oxidizing atmosphere.
➢ Gases cause the ejection of tiny droplets away from the
droplet surface, although sometimes boiling may become
violent enough to cause the total disruption of the original
droplet.
➢ Evaporation of the low boiling point components carries on
with swelling until the onset of ignition.
!
!
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!
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127
Combustion of Fuel
!
❖ Ignition
➢ Vapor from the droplets and the hot air mix, causing an
increase in the mixture temperature.
➢ Ignition occurs when the mixture reaches its flammability limits.
➢ The time taken for ignition is named Pre-ignition Delay (ti),
which has been frequently related to an Arrhenius-type
expression like the following (Malik (1986):
➢ The onset of combustion causes slight thermal decomposition.
➢ The heat released produces further fuel evaporation from the
fuel droplet.
➢ Then the viscosity of the residue increases as large paraffin’s
are broken down, side chains are stripped from Asphaltenes
and similar molecules, undergoing condensation to form
carbon-like structures.
!
!
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!
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128
Combustion of Fuel
!
❖ Coke Formation
➢ The evolution of the volatile matter ends abruptly and the
droplet collapses forming a rigid carbonaceous residue,
known as cenosphere.
➢ Oils with higher Asphaltenes content show the least
contraction and form large thin-walled coke shells
approximately the size of the original droplet.
➢ Experimental observations indicate that these materials
become rigid while still evolving decomposition vapor,
because their aromatic structures are very suitable for rapid
carbon formation.
➢ The final amount of oil mass remaining in the solid residue
represents between 0.5 and 10 % of the original drop mass.
!
!
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!
!
NMLC-EF1-Module 4
129
Combustion of Fuel
!
❖ Coke structure and burn-out
!
➢ Coke particles thus formed are spherical and hollow.
➢ The carbonaceous residue then undergoes slow
heterogeneous combustion at a rate of one-tenth of that of
the initial droplet, representing as much as 50 % of the total
burning time of the droplet.
➢ In large particles at high temperature, diffusion of oxidant
species control the reaction rate, whereas in small particles
at low temperature the surface reactions control the reaction
rate.
!
!
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!
NMLC-EF1-Module 4
130
Combustion of Fuel
Different Combustion Stages
The pre-ignition delay period
➢ This is the time elapsing
between the insertion of the
droplet in the furnace and the
time when an envelope flame
establishes around the droplet.
➢ The most important process
taking place involves the
evaporation of volatiles from
the droplet.
!
!
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!
!
NMLC-EF1-Module 4
131
Combustion of Fuel
The flame period
➢ Ignition is marked by a sharp
increase in the temperature and
light emitted by the burning
specimen.
➢ The temp. rises as smaller amounts
of volatiles are evaporated.
➢ Cracking turns out to be the
source of more volatiles.
➢ A solid residue is left, which
collapses onto the thermocouple
when the flame disappears.
!
!
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!
NMLC-EF1-Module 4
132
Combustion of Fuel
The coke-ignition period
➢ Hot gases reach the particle
surface and heterogeneous
reactions take place between
oxygen and carbon, in a highly
exothermic process that
increases the particle temp.
while a red glow is emitted.
➢ Quenching occurs when heat
losses exceed heat generation.
The coke-ignition delay period
Soot residue left after combustion
!
!
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!
NMLC-EF1-Module 4
133
Combustion of Fuel
Fuel Viscosity and Droplet Size and Ignition Delay
!
Several techniques have been evolved to reproduce the very
demanding conditions occurring in combustion chambers.
!
Single Suspended Droplet Technique
!
The single suspended droplet technique consists of placing a
droplet of chosen, but variable, size on a fiber or metal wire and
subjecting it to the effects of energy emission in the form of
gas-flame ignition, immersion in a furnace or radiation from a
lamp.
!
!
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!
NMLC-EF1-Module 4
134
Combustion of Fuel
Fuel Viscosity and Droplet Size and Ignition Delay
!
Criticism of the Suspended Droplet technique stems from
various facts:
1. Droplet sizes used are generally several times larger than
those in real furnace operation, thus not truly
representative of spray combustion.
1. Heating rates may be comparable to those in large
furnaces, but convective streams affect the natural
shape of the flame.
1. If a radioactive source of heat is employed, the heating
rate is influenced by the different infrared absorbance of
the sample components.
!
!
NMLC-EF1-Module 4

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