Complete Oil Analysis

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

DIFFERENT TYPES OF OILS USED IN POWER PLANT • FUEL OIL • LUBRICATING OIL • FIRE RESISTANT FLUID • INSULATING OIL or TRANSFORMER OIL

FUEL OIL • FUEL OILS BEING USED AT POWER STATIONS - LDO - HSD - FO (FURNACE OIL)

- LSHS (LOW SULPHUR HEAVY STOCK)

LDO & HSD • • • • • • •

LOW VISCOSITY LOW FLASH POINT COSTLY NO NEED OF HEATING NO STEAM REQUIRED CV ~10720 KCAL/KG IDEAL FOR STARTING OF BOILER FROM COLD

FURNACE OIL • MUCH 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 oil • Standard: 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 Monitoring… • GCV: 10270 kcal/kg • Total Sulphur : 3.5-4.0-4.5% by weight

• Water Content • Ash content • Sediments

FUNCTIONS OF FO • Coal 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 CHECKED

• KINEMATIC 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 CHECKED • • • • • • •

Foaming Characteristics Copper strip corrosion Emulsion Characteristics Cloud and pour point Acidity Oxidation Characteristics Flash point

LIMIT OF DIFFERENT LUBE OIL S.No

Equipment

1

MOT/BFP/ ID/FD

2

Stage

Name of oil

Moisture (ppm)

MI (ppm)

Viscosity (cst)

I

SERVO PRIME-32

150

50

27.6-36.3

PA FAN

I

SP-68

150

50

60.8-79.2

3

CT FAN/ASPH

I

SERVO 200 SYSTEM-121

500

118-124

4

MILL GEAR HOUSING

I

SERVO MESH SP320

0.1%

320-350

1000

LIMIT OF DIFFERENT LUBE OIL S.N o

Equipment

Stage

Name of oil

Moisture (ppm)

MI (ppm)

Viscosity (cst)

1

TURBINE

II

DAPHANE SUPER TURBINE-46

100

50

41.4-50.6

2

PA FAN/SAPH

II

SERVO CYCLE-660

100

50

615-680

3

FD/ID

II

SERVO PM68

100

50

64-72

4

TDBFP BRG & COUPLING

II

SERVO PM46 T

300

50

43-48

5

MDBFP

II

SERVO SYSTEMHLP32

300

50

29-39

6

MAIN MILL LUBE UNIT

II

SERVO 500 SYSTEM-460

500

440-500

FIRE RESISTANT FLUID

FIRE RESISTANT FLUID • FRF is known as phosphate ester hydraulic fluids. • They are used in 500 MW turbine control system • They 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 Hydrolysis • Fluid Cleanliness/ Particle Count • Total Acid No-Hydrolysis that has occurred • Mineral oil content • Air release • Viscosity • Resistivity

FRF POLISHING UNIT • Mechanical 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 S.N Parameter

Test Method

Permissible Limit

1

Viscosity

ASTM D-445

30-50 cst

2

Acid Number

ASTM D-974

0.2 mg KOH/gm

3

Water Content

ASTM D-1744

1500 ppm

4

Sediments

AFNORE-48652

5 mg/100 ml

5

Particle Count

ASTMF-662/322

Class 16/13

INSULATING OIL

USE OF INSULATING OIL • Insulating 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 OPERATION • • • •

Increased temperature. Absorption of gases mainly oxygen. Absorption of water from atmosphere. Ageing through contacts with metal plates like copper and iron • High 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 OIL • Reconditioning 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 oil • Electrical 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 S.N

Phenomenon

Gases Generated

1

Partial discharge

H2 gas (mainly)

2

Little heating

CH4,H2

3

Low temp. hotspot

CH4

4

Moderately high temp hotspot Very high temp hotspot

C2H4,C2H6

5

C2H2 in significant amount.

Steps involved in D G Analysis • Sampling 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 Analysis • Analysis 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 FLUIDS • SOLUBLE 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 FLUID • BETTER 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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