ANALYSIS & TESTING OF FUEL OIL LUB OIL INSULATING OIL & HYDRAULIC FLUIDS

DIFFERENT TYPES OF OILS USED IN POWER PLANTFUEL OIL

LUBRICATING OIL

FIRE RESISTANT FLUID

INSULATING OIL or TRANSFORMER OIL

FUEL OILFUEL OILS BEING USED AT POWER STATIONS

LDO

HSD

FO (FURNACE OIL)

LSHS (LOW SULPHUR HEAVY STOCK)

LDO & HSDLOW VISCOSITYLOW FLASH POINTCOSTLYNO NEED OF HEATINGNO STEAM REQUIREDCV ~10720 KCAL/KGIDEAL FOR STARTING OF BOILER FROM COLD

FURNACE OILMUCH HIGHER VISCOSITY THAN LDO OR HSD

REQUIRES HEATING AT THE TIME OF UNLOADING & PUMPING

PREHEATING UPTO 110 DEGC FOR USE

BETTER ATOMISED WITH STEAM

COMPARATIVELY CHEAPER THAN LDO & HSD

CV ~ 10270 KCAL/KG

**LSHS- HIGHLY VISCOUS, CHEAPER THAN FO

Parameters Monitored of Fuel oilStandard: IS 1593/1971, Grades: LV-MV-HV

API gravity: 12 sp. 0.986 at 15 degc

Viscosity- 80-120-370 cst at 50 degc

Flash point- 66 degC (min)

Pour point

FO MonitoringGCV: 10270 kcal/kg

Total Sulphur : 3.5-4.0-4.5% by weight

Water Content

Ash content Sediments

FUNCTIONS OF FOCoal fired units contains oil burners having capacity of 15-20%

Ignition energy to light off coal burners

Stabilization of coal flame at low loads

Safe and reliable heat input source during light up of boiler

PROPERTIES OF LUB OIL TO BE CHECKEDKINEMATIC VISCOSITY: The Redwood viscometer determines the time usually expressed in sec required for a standard volume of oil to flow through a standard orifice at specified pr. & temp.

Kinematic viscosity= const. x time

Moisture content: By Crackle test or by Karl Fischer titration method

Mechanical Impurities: A fixed volume of oil is dissolved in a solvent like Toluene or Pet. Ether and passed through pre weighed 45 micron filter paper. MI is determined from difference in weight

PROPERTIES OF LUBRICATING OIL TO BE CHECKEDFoaming CharacteristicsCopper strip corrosionEmulsion CharacteristicsCloud and pour pointAcidityOxidation Characteristics Flash point

LIMIT OF DIFFERENT LUBE OIL

LIMIT OF DIFFERENT LUBE OIL

FIRE RESISTANT FLUID

FIRE RESISTANT FLUIDFRF is known as phosphate ester hydraulic fluids.They are used in 500 MW turbine control systemThey are fire resistant, exhibit good resistance to oxidation hydrolysis, adequate air release and low foaming properties when compared to petroleum oil.

PARAMETERS OF FRF MONITORED Water Content-Potential for HydrolysisFluid Cleanliness/ Particle CountTotal Acid No-Hydrolysis that has occurredMineral oil contentAir releaseViscosityResistivity

FRF POLISHING UNITMechanical filter and strainers removes mechanical impurities

Fuller earth and activated alumina treatment to remove acidic ions. They acts as ion exchangers.

Air drier or desiccant breather to remove moisture-moisture filter.

LIMIT OF DIFFERENT PARAMETERS

INSULATING OIL

USE OF INSULATING OILInsulating oils are derived from mineral oil.Insulating oils are used in transformers, reactors switchgear and cables.It quenches arcs when switching.Prevents glow discharge.Act as a cooling agent.

AGEING OF OIL DURING OPERATIONIncreased temperature.Absorption of gases mainly oxygen.Absorption of water from atmosphere.Ageing through contacts with metal plates like copper and ironHigh temperature decomposition.

PARAMETERS OF INSULATING OIL MONITORED Dielectric breakdown test.

Dielectric dissipation factor or tan-d.

Specific resistances.

Water content test.

Acidity Test.

RECONDITIONING OF INSULATING OILReconditioning of oil means removal of water and solid particles from oil.This is done by using several available type of filters, centrifuge and vacuum dehydrators.Filter removes mechanical impurities.The centrifuge is used when there is large amount of water or other contamination present.Vacuum dehydrator removes water and dissolved gases.

Condition Monitoring of HV Transformers and Reactors by DGA technique

Degradation of insulating oilElectrical discharges or thermal stresses in the oil or solid insulator of an oil filled transformer produces gases.The most significant gases produced are hydrogen, methane, ethane, ethylene and actylene.The relative quantity of various gases depends on the energy available.

GASES GENERATED UNDER DIFFERENT CONDITION

Steps involved in D G AnalysisSampling of oil - Stainless steel oil sampling containers of capacity up to 1000 ml with needle valves and tube adaptors at both ends can be used for sampling.Gas Extraction from oil Dissolved gases are extracted by degassing flask attached with a vacuum pump assembly. The extracted gas is then compressed to atmospheric pressure and volume of the gas is measured.

Steps involved in D G AnalysisAnalysis of gas extracted- The gas extracted can be analyzed by a Gas Chromatograph fitted with a thermal conductivity cell detector. The carrier gas is helium. The column used is poropak N and Molecular sieve 5A.The gases determined are Hydrogen, oxygen, nitrogen, methane, ethane, ethylene, acetylene, propane, propylene, CO, CO2 etc.

HYDRAULIC FLUIDS

MINERAL OIL HYD FLUIDSSOLUBLE IN WATER, FORMING EMULSIONS

USED WHERE NOT MANY MOVING PARTS ARE INVOLVED

CHEAP

IF LEAK OCCURS, PRESENT A DEFINITE FIRE HAZARD AT ELEVATED TEMP

WATER/GLYCOL HYD FLUIDBETTER OILLINESS THAN MINERAL OIL HF

ARE REASONABLY FIRE RESISTANT

FLUID BECOMES THICKER & STICKY AT HIGH TEMP

WATER CAN BE ADDED TO RESTORE ITS ORIGINAL CONSISTENCY

MORE EXPENSIVE THAN THE SOLUBLE MINERAL OIL HF

SYNTHETIC HYDRAULIC FLUID MAN-MADE PRODUCT

CHEMICAL NAMES SUCH AS CHLORINATED HC & PHOSPHATE ESTERS

HIGH RESISTANCE TO FIRE

USED IN BOILER DAMPERS & OTHER SYSTEMS WHERE HIGH TEMP ARE ENCOUNTERED

COSTS ABOUT 8 TIMES AS MUCH AS MOHF

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