Effects of Impurities in Fuel Oil

Q. Write brief notes on the adverse effects that a fuel containing high value of the following may cause: (a) Viscosity (b) Density (c) Sulphur (d) Corodson Carbon Residue (e) Asphaltene (f) Vanadium & Sodium (g) Ash (h) Water

Viscosity

High viscosity of fuel may cause the following effects being using high temperature heating

– Fouling of Oil heater

– Gassing of Fuel

– Thermal expansion to fuel pump and injector component leading to seizure or sticking

– Clogging of filter

Density

High density of fuel oil means high contents of impurities . It may effect to

– Filter clogging

– High temperature require for sedimentation & purification

– Upsetting to purifiers

– Being fuel pump is volume-measuring device , produce more heat when combustion .

Ash

Natural ash are usually Silicon , Aluminium , Calcium , Iron , Nickle , Vanadium and Sodium . If high ash content may effect the following

– High density

– Defects in filtration and purification

– Deposits may effect as abrasive wear to piston rings , liner , fuel pump components , T.C turbine blades

– Dangerous effect of Vanadium and Sodium may shorter exhaust valve life.

Water

More than 1 % of water content may cause

– Corrosion on fuel pump and injector component tend to seizure.

– Misfiring of engine and stop in extreme case

– Poor combustion , reduce out put and T.C surging

– Emulsification of fuel leading to sludge formation

– Fuel foaming in mixing column

– Promote microbial degradation

– Loss of energy content and quantity of fuel.

Sludge

It may cause

– Instability of fuel

– Blockage of filters

– Upsetting of purifier operation

Asphaltenes

It is a hydrocarbon compound of solid combustible substances which are insoluble in fuel oil. Asphaltenes may cause

– Clogging of filters ,Fouling of heaters and upsetting purifier operation

– Corrosion of fuel pump’s component and seizure

– Sticking of nozzles and tend to trumpet formation

– Prolong combustion time and its flame close to liner wall and overheat , burn cyl. L.O

– Due to poor combustion , unburned products tend to abrasive wear of Piston Rings & Liners , seizure & broken piston rings.

– Fouling of scavenge port and exhaust system

Sulphur

– Produce combustion products containing SO2 & SO3 to cause cold corrosion wear of

Piston rings, Liners ,Turbocharger water cooled casing , Exhaust valve cage….. ect.

– High temperature corrosion to exhaust valve.

– Adhesion of black lacquer on the liner inner surface

– Form L.O acidity condition.

Vanadium,Sodium

May cause hot corrosion during combustion . They are formed corrosive products as SODIUM VANADATE COMPOUND when combustion temperature 530 ‘C , stick to the metal and attack the protective coating of the surface , cause hot corrosion especially to Exhaust valve , Turbocharger turbine blades and nozzle ring.

Carbon residue Poor combustion with smoky exhaust and produce depositing product effect to ….

– Trumpet formation of nozzle

– Depositing Piston ring zone tend to seizure and broken

– Remove cylinder L.O film and act as abrasive to wear Piston rings and liners, – –

– Fouling of scavenge space and inlet / exhaust ports

– Depositing in Turbocharger and corrosion to nozzle ring and turbine blades

– Fouling at Economizer and uptake

Catalytic Fines.

These are very small size of 3 ~ 100 microns, hard and abrasive compound of Alumina and Silica.

Larger parts may increase wear in fuel pump and valve components

Smaller parts below 5 micron promote Piston rings & Liner wear.