Marine Fuel Oil. Combustion ► The rapid chemical combination of oxygen with the combustible...

Marine Fuel OilMarine Fuel Oil

CombustionCombustion

►The rapid chemical combination of The rapid chemical combination of oxygen with the combustible elements oxygen with the combustible elements of a fuel resulting in the production of of a fuel resulting in the production of heat and light.heat and light.

FuelFuel

► A fuel may be defined as any A fuel may be defined as any combustible material which when combustible material which when burned gives off heat.burned gives off heat. Fuel OilFuel Oil CoalCoal WoodWood

Crude OilCrude Oil

►Crude oil and the products derived Crude oil and the products derived from the raw material are considered from the raw material are considered petroleum products.petroleum products.

►Crude oil is a mixture of a wide range Crude oil is a mixture of a wide range of long chain hydrocarbon molecules.of long chain hydrocarbon molecules.

►A hydrocarbon molecule is essentially A hydrocarbon molecule is essentially one or more hydrogen atoms linked one or more hydrogen atoms linked with one or more carbon atoms.with one or more carbon atoms.

Source: Tanker Operations 4th Edition by M. Huber

Crude OilCrude Oil►The composition of crude oil varies The composition of crude oil varies

widely depending on its geographic widely depending on its geographic source.source.

►Crude oil can be described as either Crude oil can be described as either “Heavy” or “Light” based on its “Heavy” or “Light” based on its specific gravity (S.G.).specific gravity (S.G.).

►The number of carbon atoms in the The number of carbon atoms in the hydrocarbon molecule influences the hydrocarbon molecule influences the specific gravity of a crude oil.specific gravity of a crude oil.


Crude OilCrude Oil

►The greater the number of carbon The greater the number of carbon atoms in the molecule, the heavier atoms in the molecule, the heavier the molecule will be.the molecule will be.

►Crude oil vary from very sweet to Crude oil vary from very sweet to sour in hydrogen sulfide content.sour in hydrogen sulfide content.

►From heavy to light in weightFrom heavy to light in weight►From yellow to black in colorFrom yellow to black in color


Crude OilCrude Oil

►Crude oils generally fall into three Crude oils generally fall into three classifications:classifications:

►Asphalt based crudes contain little Asphalt based crudes contain little paraffin and are often high in sulfur, paraffin and are often high in sulfur, nitrogen and oxygen. These are used nitrogen and oxygen. These are used for making gasoline and asphalt.for making gasoline and asphalt.

►Paraffin-based crudes are high in Paraffin-based crudes are high in paraffin wax and can be refined into paraffin wax and can be refined into motor fuels, lube oils and kerosene.motor fuels, lube oils and kerosene.


Crude OilCrude Oil

► Mixed-base crudes have some Mixed-base crudes have some amounts of both paraffin wax and amounts of both paraffin wax and asphalt in them and can be refined asphalt in them and can be refined into virtually all products, but of into virtually all products, but of course in lesser amounts.course in lesser amounts.


RefiningRefining►The first step in the manufacture of The first step in the manufacture of

petroleum products is he separation of petroleum products is he separation of crude oil into its main fractions using crude oil into its main fractions using atmospheric distillation.atmospheric distillation.

►When the crude oil is heated the When the crude oil is heated the lightest and most volatile lightest and most volatile hydrocarbons boil off as followed by hydrocarbons boil off as followed by the heaviest and least volatile the heaviest and least volatile hydrocarbons.hydrocarbons.

►The vapors are then cooled and The vapors are then cooled and condensed back into liquidscondensed back into liquids

Source: A Practical Guide to Marine Fuel Oil Handling by Leigh-Jones

RefiningRefining► The atmospheric The atmospheric

distillation process distillation process is carried out in a is carried out in a fractionating fractionating column which is column which is divided into a series divided into a series of chambers by of chambers by perforated trays the perforated trays the condense vapors at condense vapors at each stage to allow each stage to allow the liquids to flow the liquids to flow into storage tanks.into storage tanks.


RefiningRefining

►The residue from atmospheric distillation The residue from atmospheric distillation is sometimes referred to as “long is sometimes referred to as “long residue”.residue”.

►Further distillation is carried out at a Further distillation is carried out at a reduced pressure and high temperature reduced pressure and high temperature to recover more distillate product.to recover more distillate product.

►This distillation is known as “vacuum This distillation is known as “vacuum distillation”.distillation”.

►The residue from vacuum distillation is The residue from vacuum distillation is sometimes called “short residue”.sometimes called “short residue”.


RefiningRefining

►Residue or “feedstock” from the Residue or “feedstock” from the atmospheric or vacuum distillation atmospheric or vacuum distillation units or a mixture of the two in most units or a mixture of the two in most cases then undergoes further cases then undergoes further distillation thru a thermal cracking distillation thru a thermal cracking processprocess

►There are three types of thermal There are three types of thermal cracking visbreaking, a thermal gas oil cracking visbreaking, a thermal gas oil unit and coking.unit and coking.


Refining Refining

►Visbreaking is a mild form of thermal Visbreaking is a mild form of thermal cracking often used to reduce the cracking often used to reduce the viscosity of straight run residual fuels.viscosity of straight run residual fuels.

► In most cases these fuels are highly In most cases these fuels are highly viscous and if required for sale as viscous and if required for sale as heavy fuel oil must be blended with heavy fuel oil must be blended with relatively high value distillate to meet relatively high value distillate to meet the finished product specification.the finished product specification.


RefiningRefining

► Visbreaking reduces Visbreaking reduces the quantity of the quantity of distillate required to distillate required to dilute or “cutter stock”.dilute or “cutter stock”.

► A thermal gas unit is A thermal gas unit is used to produce and used to produce and recover maximum recover maximum amount of gas oil.amount of gas oil.

► In extreme cases the In extreme cases the viscosity of the residue viscosity of the residue may be higher then may be higher then that of the feed stock.that of the feed stock.


RefiningRefining

►Coking is a relatively severe form of Coking is a relatively severe form of thermal cracking designed to convert thermal cracking designed to convert straight run residues into more straight run residues into more valuable products such as naphtha valuable products such as naphtha and diesel oil.and diesel oil.

►Gas oil and coke are also produced, Gas oil and coke are also produced, therefore, coking does not feature in therefore, coking does not feature in the manufacture of residual fuel oils.the manufacture of residual fuel oils.


RefiningRefining

►Catalytic cracking is carried out in a Catalytic cracking is carried out in a large processing plant, employing a large processing plant, employing a fluidized catalyst, usually a silica fluidized catalyst, usually a silica based material in direct contact with based material in direct contact with the feedstock.the feedstock.

►A catalyst is a substance which aids A catalyst is a substance which aids and accelerates a chemical reaction, and accelerates a chemical reaction, but which itself undergoes no but which itself undergoes no permanent change in composition.permanent change in composition.


RefiningRefining

►The very fine powdered fine catalyst The very fine powdered fine catalyst flows like a fluid when kept in constant flows like a fluid when kept in constant agitation and circulated by steam, air or agitation and circulated by steam, air or vapor. vapor.

► In the plant, as the preheated heavy gas In the plant, as the preheated heavy gas oil feedstock enters the reactor, it is met oil feedstock enters the reactor, it is met by a stream of hot regenerated catalyst.by a stream of hot regenerated catalyst.

►This vaporizes the feedstock, which in This vaporizes the feedstock, which in turn “fluidizes” the catalyst.turn “fluidizes” the catalyst.


RefiningRefining► Cracking occurs in the Cracking occurs in the

reactor and the reactor and the cracked oil vapors, cracked oil vapors, composed of new, composed of new, smaller molecules are smaller molecules are separated into gases, separated into gases, high quality gasoline high quality gasoline components, light gas components, light gas oil used as heating oil oil used as heating oil and a heavy gas oil and a heavy gas oil known as “cycle oil”.known as “cycle oil”.

Source: Marine Engineering by Harrington

RefiningRefining

Source: Modern Marine Engineers Manual Volume I, 3rd Edition by Hunt

Marine Fuel Oil Marine Fuel Oil CharacteristicsCharacteristics

►Various grades of fuel are referred to Various grades of fuel are referred to by different names depending on the by different names depending on the terminology of the supplier.terminology of the supplier.

►Gas oil is used in some smaller vessels Gas oil is used in some smaller vessels and the auxiliary engines of larger and the auxiliary engines of larger vessels.vessels.

►This grade of fuel is marketed under This grade of fuel is marketed under various names including bunker gas oil various names including bunker gas oil and marine gas oil.and marine gas oil.


► Such fuel is a light distillate with a clear, Such fuel is a light distillate with a clear, bright appearance and is a clean fuel in that bright appearance and is a clean fuel in that it does not contain any residual components.it does not contain any residual components.

► In contrast diesel fuel may contain a small In contrast diesel fuel may contain a small amount of residual fuel and be dark or black amount of residual fuel and be dark or black in color. in color.

► It is know by various names including light It is know by various names including light diesel and marine distillate.diesel and marine distillate.

► Blended diesel oil does contain some residue Blended diesel oil does contain some residue and is frequently called marine diesel oil.and is frequently called marine diesel oil.

Marine Fuel Oil CharacteristicsMarine Fuel Oil CharacteristicsBPBP CHEVROCHEVRO

NNESSOESSO MOBILMOBIL SHELLSHELL TEXACOTEXACO

Marine Marine

Fuel OilFuel Oil

(MFO)(MFO)

IntermediateIntermediate

Bunker FuelBunker Fuel

(IBF*)(IBF*)

BunkerBunker

Fuel OilFuel Oil

(BFO)(BFO)

MotorshipMotorship

Fuel OilFuel OilMarine FuelMarine Fuel

Oil (MFO*)Oil (MFO*)InterfuelInterfuel

(IF*)(IF*)

InterfuelInterfuel

(IF)(IF)

IntermediateIntermediate

Bunker FuelBunker Fuel

(IBF*)(IBF*)

IntermediaIntermediatete

FuelFuel

(IF*)(IF*)

Light Marine Light Marine

Fuel OilFuel Oil

(LMFO)(LMFO)

Marine FuelMarine Fuel

Oil (MFO*)Oil (MFO*)IF*IF*

Marine Marine Diesel OilDiesel Oil

(MDO)(MDO)

Marine Marine DieselDiesel

OilOil

(MDO)(MDO)

MarineMarine

Diesel OilDiesel Oil

(MDO)(MDO)

MarineMarine


(MDO)(MDO)

MarineMarine


(MDO)(MDO)

MarineMarine


(MDO)(MDO)

LightLight


(LDO)(LDO)

LightLight

DieselDiesel

LightLight


(LDO)(LDO)

DistillateDistillate

MarineMarine


MarineMarine

Diesel Fuel Diesel Fuel or Gas Oilor Gas Oil

MarineMarine

DistillateDistillate

Marine Marine

Gas OilGas Oil

(MGO)(MGO)

Gas OilGas Oil

(GO)(GO)Marine GasMarine Gas

Oil (MGO)Oil (MGO)Marine GasMarine Gas

Oil (MGO)Oil (MGO)Gas OilGas Oil

(GO)(GO)Gas OilGas Oil

(GO)(GO)

* Denotes a specific grade, usually shown by viscosity of the grade in cSt at 50 * Denotes a specific grade, usually shown by viscosity of the grade in cSt at 50 °F°F

Flash Flash PointPoint

°C (°F)°C (°F)

Pour Pour PointPoint

°C (°F)°C (°F)

Water Water andand

SedimeSedimentnt

%%

CarbonCarbon

ResidueResidue

%%

AshAsh

WeightWeight

%%

S.G.S.G.

60/6060/60°F°F

Deg APIDeg API

SulfurSulfur

%%

Grade of Fuel OilGrade of Fuel Oil MinMin MaxMax MaxMax MaxMax MaxMax MaxMax MaxMax

No. 1 Distillate oil No. 1 Distillate oil intended for intended for vaporizing burnersvaporizing burners

38 38 (100)(100) -18 (0)-18 (0) 0.050.05 0.150.15

0.84990.8499

(35 min)(35 min)0.5 or0.5 or

legallegal

No. 2 Distillate oil for No. 2 Distillate oil for general purpose general purpose heating heating

38 38 (100)(100) -6 (20)-6 (20) 0.050.05 0.350.35

0.84990.8499

(35 min)(35 min)

0.5 or0.5 or

legallegal

No. 4 Preheating not No. 4 Preheating not usually required for usually required for handlinghandling

55 55 (130)(130) -6 (20)-6 (20) 0.500.50 0.100.10 legallegal

No. 5 (Light) No. 5 (Light) Preheating may be Preheating may be required depending required depending on climateon climate

55 55 (130)(130) 1.001.00 0.100.10 legallegal

No.5 (Heavy) No.5 (Heavy) Preheating may be Preheating may be for burning and in for burning and in cold climates be cold climates be required for handlingrequired for handling

55 55 (130)(130) 1.001.00 0.100.10 legallegal

No. 6 Preheating No. 6 Preheating required for burning required for burning and handlingand handling

6060

(140)(140)2.002.00 legallegal

Saybolt Viscosity Saybolt Viscosity Universal at 38Universal at 38°C Furol at 50 °C Furol at 50 °C°C

Kinematic Viscosity cStKinematic Viscosity cStAt 38 At 38 °C (100 °F) At 50 °C (122 °C (100 °F) At 50 °C (122 °F)°F)

Grade of Fuel Grade of Fuel OilOil MinMin MaxMax MinMin MaxMax MinMin MaxMax MinMin MaxMax

No. 1 Distillate oil No. 1 Distillate oil intended for intended for vaporizing burnersvaporizing burners

1.41.4 2.22.2

No. 2 Distillate oil No. 2 Distillate oil for general purpose for general purpose heating heating

(32.6)(32.6) (37.9)(37.9) 2.02.0 3.63.6

No. 4 Preheating No. 4 Preheating not usually required not usually required for handlingfor handling

(45)(45) (125)(125) 5.85.8 26.426.4

No. 5 (Light) No. 5 (Light) Preheating may be Preheating may be required depending required depending on climateon climate

(>125)(>125) (300)(300) 26.426.4 6565

No.5 (Heavy) No.5 (Heavy) Preheating may be Preheating may be for burning and in for burning and in cold climates be cold climates be required for required for handlinghandling

(>300)(>300) (900)(900) (23)(23) (40)(40) >65>65 194194 (42)(42) (81)(81)

No. 6 Preheating No. 6 Preheating required for burning required for burning and handlingand handling

(>900)(>900) (9000(9000))

(>45(>45))

(300)(300) >92>92 638638 50 50 °C°C (122 (122 °F°F))


►DensityDensity►ViscosityViscosity►Flash PointFlash Point►Fire PointFire Point►Pour PointPour Point►Carbon ResidueCarbon Residue►AshAsh


►WaterWater►SulfurSulfur►Vanadium and SodiumVanadium and Sodium►Aluminum and SiliconAluminum and Silicon►Sediment and StabilitySediment and Stability►CompatibilityCompatibility►Specific EnergySpecific Energy► Ignition QualityIgnition Quality

DensityDensity

►Density is the absolute relationship Density is the absolute relationship between mass and volume at a stated between mass and volume at a stated temperature.temperature.

►The SI unit is kg/mThe SI unit is kg/m33 and the standard and the standard temperature is 15 temperature is 15 °C is used for the density °C is used for the density calculation of petroleum and its products.calculation of petroleum and its products.

►The density is required for quantity The density is required for quantity calculations and to select the optimum size calculations and to select the optimum size of gravity disc for the centrifuge.of gravity disc for the centrifuge.

DensityDensity

►The Specific Gravity (S.G.) of a substance The Specific Gravity (S.G.) of a substance is the ratio of the mass of a given volume is the ratio of the mass of a given volume to the mass of an equal volume of water to the mass of an equal volume of water at the same temperature.at the same temperature.

►The relative density of a substance is the The relative density of a substance is the ratio of the mass of a given volume at a ratio of the mass of a given volume at a temperature ttemperature t11 to the mass of a given to the mass of a given volume of pure water at temperature tvolume of pure water at temperature t22..

DensityDensity

► In the United States and some other In the United States and some other countries, the density of petroleum countries, the density of petroleum products is defined in terms of API products is defined in terms of API gravity.gravity.

►This is an arbitrary scale adopted by This is an arbitrary scale adopted by the American Petroleum Institute to the American Petroleum Institute to express relative density of oils.express relative density of oils.

►API gravity (degrees) = (141.5 / API gravity (degrees) = (141.5 / Relative density @ 60 / 60Relative density @ 60 / 60° F) – 131.5° F) – 131.5

ViscosityViscosity

►Dynamic viscosity is a property of the Dynamic viscosity is a property of the internal resistance of a fluid that internal resistance of a fluid that opposes the motion of adjacent layers.opposes the motion of adjacent layers.

►The unit of measure of this resistance The unit of measure of this resistance in SI units is a Pascal.in SI units is a Pascal.

►Frequently the unit Poise is used Frequently the unit Poise is used where 1 Pascal =10 Poise.where 1 Pascal =10 Poise.

►Dynamic viscosity can also be referred Dynamic viscosity can also be referred to as absolute viscosity.to as absolute viscosity.

ViscosityViscosity

►Marine fuel viscosity is usually Marine fuel viscosity is usually expressed in kinematic viscosity which expressed in kinematic viscosity which is measured in Stokes.is measured in Stokes.

►Kinematic viscosity is the quotient of Kinematic viscosity is the quotient of the dynamic viscosity or absolute the dynamic viscosity or absolute viscosity divided by density with both viscosity divided by density with both expressed at the same temperature.expressed at the same temperature.

ViscosityViscosity

► Since one Stoke is a large unit, kinematic Since one Stoke is a large unit, kinematic viscosity is usually measured in centistokes viscosity is usually measured in centistokes (cSt), one cSt = 1 mm(cSt), one cSt = 1 mm22 / sec. / sec.

► Viscosity can also be quoted in Saybolt, Viscosity can also be quoted in Saybolt, Engler or Redwood.Engler or Redwood.

► Typical maximum fuel viscosity for transfer Typical maximum fuel viscosity for transfer is 800 – 1000 cSt.is 800 – 1000 cSt.

► For a boiler the atomization viscosity For a boiler the atomization viscosity depends on the burner and can be in a depends on the burner and can be in a range of 15 – 65 cSt.range of 15 – 65 cSt.

ViscosityViscosity

►For a diesel engine the injection For a diesel engine the injection viscosity can be in the range of 8 – 27 viscosity can be in the range of 8 – 27 cSt with the range usually 13 -17 cSt.cSt with the range usually 13 -17 cSt.

►Generally if the actual viscosity is Generally if the actual viscosity is greater than that ordered, the greater than that ordered, the viscosity can be achieved by the fuel viscosity can be achieved by the fuel oil heaters but the performance of the oil heaters but the performance of the centrifuge can fall below design centrifuge can fall below design conditions.conditions.

Flash PointFlash Point

►The Flash Point of a fuel oil is defined The Flash Point of a fuel oil is defined as the lowest temperature at which as the lowest temperature at which the oil gives off vapors in sufficient the oil gives off vapors in sufficient quantity to combust when mixed with quantity to combust when mixed with air in the presence of a ignition source.air in the presence of a ignition source.

► If the combustion source is removed If the combustion source is removed combustion will stop.combustion will stop.

►The flash point of fuel oil generally The flash point of fuel oil generally should not be lower than 150 should not be lower than 150 °F.°F.

Fire PointFire Point

►The Fire Point is defined as the lowest The Fire Point is defined as the lowest temperature at which a fuel oil gives temperature at which a fuel oil gives off vapors in sufficient quantity to burn off vapors in sufficient quantity to burn continuously when a flame is applied.continuously when a flame is applied.

►The Fire Point is generally 10 The Fire Point is generally 10 °F to 15 °F to 15 °F higher than the Flash Point.°F higher than the Flash Point.

Pour PointPour Point

►The Pour Point is the lowest The Pour Point is the lowest temperature at which a fuel oil will temperature at which a fuel oil will solidify.solidify.

Carbon ResidueCarbon Residue

►The Carbon Residue of a fuel is the The Carbon Residue of a fuel is the tendency of carbon deposits to form tendency of carbon deposits to form under high temperature conditions in under high temperature conditions in an inert atmosphere.an inert atmosphere.

► It can be expressed as Ramsbottom It can be expressed as Ramsbottom Carbon Residue (RCR), Conradson Carbon Residue (RCR), Conradson Carbon Residue (CCR) or Micro Carbon Carbon Residue (CCR) or Micro Carbon Residue (MCR).Residue (MCR).

Carbon ResidueCarbon Residue

►Carbon Residue is considered to be an Carbon Residue is considered to be an indication of the combustibility and indication of the combustibility and deposit forming tendency of a fuel.deposit forming tendency of a fuel.

►The Carbon Residue of a fuel depends The Carbon Residue of a fuel depends on the refining process employed in on the refining process employed in the fuels manufacture.the fuels manufacture.

AshAsh

►The Ash value is related to the The Ash value is related to the inorganic material in the fuel oil.inorganic material in the fuel oil.

►The actual value depends on three The actual value depends on three factors, first the inorganic material factors, first the inorganic material naturally present in the crude oil, naturally present in the crude oil, secondly the refining processes secondly the refining processes employed and finally subsequent employed and finally subsequent contamination due to sand, dirt and contamination due to sand, dirt and rust scale.rust scale.

AshAsh

►Ash levels in distillate fuels are Ash levels in distillate fuels are negligible.negligible.

►Residual fuels have more ash forming Residual fuels have more ash forming constituents as they are concentrated constituents as they are concentrated from the residue of crude oil.from the residue of crude oil.

WaterWater

►Usually the level of water in fuel is very Usually the level of water in fuel is very low, typically 0.1 – 0.2 % by volume.low, typically 0.1 – 0.2 % by volume.

►Water can be introduced from a number Water can be introduced from a number of sources including tank condensation, of sources including tank condensation, tank leakage, leaking heating coils and tank leakage, leaking heating coils and from the purifier if the wrong gravity from the purifier if the wrong gravity disk is used.disk is used.

►Large water contamination can be Large water contamination can be removed by settling tanks and the removed by settling tanks and the remaining removed by centrifuge.remaining removed by centrifuge.

SulfurSulfur

►Sulfur is a naturally occurring element Sulfur is a naturally occurring element in crude oil, concentrated in the in crude oil, concentrated in the residual components in the crude oil residual components in the crude oil distillation process.distillation process.

►The amount of sulfur in fuel oil depends The amount of sulfur in fuel oil depends mainly on the source of the crude oil mainly on the source of the crude oil and to a lesser extent on the refining and to a lesser extent on the refining process.process.

►The sulfur amount usually varies The sulfur amount usually varies between 2 – 4 %.between 2 – 4 %.

SulfurSulfur

►The level of sulfur in the fuel has a The level of sulfur in the fuel has a marginal effect on the Heating Value of marginal effect on the Heating Value of the fuel.the fuel.

►During the combustion process in both a During the combustion process in both a diesel engine and boiler the presence of diesel engine and boiler the presence of sulfur in the fuel can cause corrosion .sulfur in the fuel can cause corrosion .

► In a diesel engine can cause corrosion In a diesel engine can cause corrosion on the cylinder liners. This can be offset on the cylinder liners. This can be offset with the use of a high alkaline lubricant.with the use of a high alkaline lubricant.

SulfurSulfur

► In a boiler the sulfur can cause In a boiler the sulfur can cause corrosive attack on the economizers.corrosive attack on the economizers.

Vanadium and SodiumVanadium and Sodium

►Vanadium is a metal present in all Vanadium is a metal present in all crude oils in a soluble form.crude oils in a soluble form.

►The levels found in residual fuels The levels found in residual fuels depends mainly on the crude oil source, depends mainly on the crude oil source, with those from Venezuela and Mexico with those from Venezuela and Mexico having the highest level.having the highest level.

►The actual level is also related to the The actual level is also related to the concentrating effect on the refinery concentrating effect on the refinery process used in the production of process used in the production of residual fuel.residual fuel.


►Fuel generally contains a small amount Fuel generally contains a small amount of sodium typically below 50 mg/kg.of sodium typically below 50 mg/kg.

►The presence of sea water increases The presence of sea water increases this value by approximately 100 mg/kg this value by approximately 100 mg/kg for each percent of sea water.for each percent of sea water.

► If not removed in the fuel treatment If not removed in the fuel treatment process a high level of sodium will give process a high level of sodium will give rise to an increase to post combustion rise to an increase to post combustion deposits in the turbocharger.deposits in the turbocharger.


►High temperature corrosion and High temperature corrosion and fouling can mainly be attributed to fouling can mainly be attributed to vanadium and sodium in the fuel.vanadium and sodium in the fuel.

►During combustion these elements During combustion these elements oxidise and form semiliquid and low oxidise and form semiliquid and low melting salts which adhere to exhaust melting salts which adhere to exhaust valves, turbochargers and boiler valves, turbochargers and boiler furnace walls.furnace walls.

Aluminum and SiliconAluminum and Silicon

► It is generally accepted that an indication of It is generally accepted that an indication of aluminum represents the potential presence aluminum represents the potential presence of catalyst fines.of catalyst fines.

► These fines are particles of spent catalyst These fines are particles of spent catalyst the arises from the catalytic cracking the arises from the catalytic cracking process in the refinery.process in the refinery.

► The fines will vary in size and hardness and The fines will vary in size and hardness and if not reduced by fuel treatment the if not reduced by fuel treatment the abrasive nature of the fines will damage the abrasive nature of the fines will damage the fuel pumps, injectors, piston rings, liner and fuel pumps, injectors, piston rings, liner and burner tips.burner tips.

Sediment and StabilitySediment and Stability

►Sediment is defined as insoluble Sediment is defined as insoluble residues that are not derived from the residues that are not derived from the fuel such as sand, dirt and rust scale.fuel such as sand, dirt and rust scale.

►The stability of a residual fuel is The stability of a residual fuel is defined as the ability of the fuel to defined as the ability of the fuel to remain in an unchanged condition, remain in an unchanged condition, despite circumstances which tend to despite circumstances which tend to cause change, or the resistance of the cause change, or the resistance of the oil to breakdown.oil to breakdown.

CompatibilityCompatibility

►While a fuel is manufactured to be While a fuel is manufactured to be stable within itself (that is, not having stable within itself (that is, not having a tendency to produce asphaltenic a tendency to produce asphaltenic sludge), it does not necessarily follow sludge), it does not necessarily follow that two stable fuels will be compatible that two stable fuels will be compatible when blended or mixed together.when blended or mixed together.

►Problems of incompatibility fuels are Problems of incompatibility fuels are rare but when they happen the results rare but when they happen the results are severe.are severe.

CompatibilityCompatibility

►Typical problems of the are sludging, Typical problems of the are sludging, and blockage of the bunker and and blockage of the bunker and service tanks, piping, filters and service tanks, piping, filters and centrifuge bowls.centrifuge bowls.

► In extreme circumstances the only In extreme circumstances the only remedy is to manually remove sludge remedy is to manually remove sludge buildup.buildup.

Heating ValueHeating Value

►The Heating Value or Specific Energy of a The Heating Value or Specific Energy of a fuel is usually expressed in BTU/lbm or fuel is usually expressed in BTU/lbm or MJ/kg depending on the fuel composition.MJ/kg depending on the fuel composition.

►For marine fuels the main components For marine fuels the main components carbon and hydrogen both release carbon and hydrogen both release energy during the combustion process.energy during the combustion process.

►The sulfur content in the fuel also The sulfur content in the fuel also releases energy during combustion, but releases energy during combustion, but to a lesser extent then the carbon and to a lesser extent then the carbon and hydrogen.hydrogen.

Heating ValueHeating Value

►The density is mainly proportional to The density is mainly proportional to the ratio of carbon and hydrogen the ratio of carbon and hydrogen atoms in the fuel.atoms in the fuel.

►The Heating Value can be calculated The Heating Value can be calculated from empirical equations.from empirical equations.

Ignition QualityIgnition Quality

►The Ignition Quality of a fuel is a measure The Ignition Quality of a fuel is a measure of the relative ease by which a fuel will of the relative ease by which a fuel will ignite.ignite.

►For distillate fuels this is measured by the For distillate fuels this is measured by the Cetane Number, which is determined by Cetane Number, which is determined by testing the fuel in a special engine that testing the fuel in a special engine that has a variable compression ratio.has a variable compression ratio.

►The higher the Cetane Number the easier The higher the Cetane Number the easier it is for the fuel to ignite in the engine.it is for the fuel to ignite in the engine.


►For residual fuel there are two For residual fuel there are two acceptable empirical equations, both acceptable empirical equations, both based on the density and viscosity of based on the density and viscosity of the fuel.the fuel.

►These are the Calculated Carbon These are the Calculated Carbon Aromaticity Index (CCAI) and the Aromaticity Index (CCAI) and the Calculated Ignition Index (CII).Calculated Ignition Index (CII).

►The CCAI gives numbers in the range The CCAI gives numbers in the range 800 – 870, while the CII gives values in 800 – 870, while the CII gives values in the same order as the Cetane Index.the same order as the Cetane Index.


►CCAI = d-81-141 log [log(VK + 0.85)]CCAI = d-81-141 log [log(VK + 0.85)]►d = density in Kg/md = density in Kg/m33 @ 15 @ 15 °C°C►VK = viscosity in mmVK = viscosity in mm22/sec @ 50 °C/sec @ 50 °C► In general CII values of less than 30 In general CII values of less than 30

and CCAI values of greater than 870 and CCAI values of greater than 870 are considered problematic.are considered problematic.

Marine Fuel Oil. Combustion ► The rapid chemical combination of oxygen with the combustible...

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Transcript of Marine Fuel Oil. Combustion ► The rapid chemical combination of oxygen with the combustible...