Turbine Lube oil system operation

1. STANDARD OPERATING PROCEDURE
LUBRICATING OIL SYSTEM
THERMAL POWER LIMITED

2. The purpose of the SOP of Lube Oil System is to train and guide operating personnel
for optimum performance of the system.
RESPONSIBILITY
Shift In-charge (Main plant) is responsible for implementation of this SOP so as to ensure safe
and efficient operation of the system.
GENERAL INTRODUCTION
The Purpose of Lube Oil System is to lubricate the Bearings of Turbo-generator unit,
supply sealing oil to Generator Hydrogen seal and Supply oil to Jacking oil pump.
The Oil supply of turbine lubricating oil system is in MOP-BOP mode. MOP is directly driven
by turbine main shaft & discharge HP oil to drive BOP to run.
The Specification of system oil is ISO-VG32 turbine oil.
The lubricating oil system performs three basic functions:
i. It reduces friction between rotating and fixed elements of the turbine and generator such as
occur in the journal bearings and thrust bearings. This reduces wear, reduces heat and improves
efficiency.
ii. It removes heat from the bearings. This heat may either be generated by friction within the
bearing or by conduction along the shaft from the turbines.
iii. In mechanical hydraulic governing systems, it is used as a hydraulic pressure fluid. In
these governing systems, lubricating oil is used for both the pilot oil and power oil
systems.
TECHNICAL SPECIFICATION
Main Oil Tank
No. of Tank 1
Highest Oil Level +100m
m
Operating Oil Temp. 35°
C
Shutdown Oil level -
150m
Lowest Oil level -
100m
Max. Operation Capacity 50.5
m3
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3. Normal Operation Capacity 34.9
m3
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4. Oil Cooler
No. of Cooler 2 (1W+ 1S)
Cooling Area 610
m3
Cooling Oil Flow 290m3
/h
Cooling Water Flow 500m3
/h
Inlet/ Outlet Oil Temp. 65°C/45°C
Cooling Water Temp. 38°
C
Oil Fume Separator
No. of Separator 1
Power 60k
W
Operating Pressure 1 MPa (10 kg/cm2
)
Operating Temp. < 80
°C
Electric Heater
No. of Heater 6
Supply A
C
Heat the oil up to 35°
C
Heating surface not higher than 150°
C
Heating surface not Lower than 100°
C
Main Oil Pump
Design Head
Motor Power
Rated Flow
Working Speed
Rated Voltage AC
415V
Main Suction Pump
Design Head 22.4
m
Motor Power 45k
W
Rated Flow 6300 ltr/min.
Working Speed 1450 r/min.
Rated Voltage AC415
V
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5. Turbine Oil Pump
Design Head 35.8
m
Motor Power 55k
W
Rated Flow 4685 ltr/min.
Rated Voltage AC415
V
Emergency Oil Pump
Design Head 31.4
m
Motor Power 40k
W
Rated Flow 3820 ltr./min.
Working Speed
Rated Voltage DC220
V
Jacking Oil Pump
Design Head
Motor Power
Rated Flow 34.3 kg/cm2 ~ 180
kg/cm2
Rated Voltage
Booster Oil Pump
Design Head
Motor Power
Rated Flow
Rated Voltage
Quality Requirements for Turbine Oil
a) Excellent thermal and oxidation
stability.
b) Good Viscosity-temperature characteristics and proper
viscosity. c) Good low temperature operating performance.
d) Excellent
demulsibility.
e) Excellent defoaming performance.
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6. f) Good rust and corrosion
resistance. g) Good air release
property.
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7. Lube oil system- Start-up Checks before Operation
1. Any PTW is not pending for Turbine Lubrication System equipment such as MOP, TOP, MSP,
EOP, JOP, BOP, Oil Fume Separator, Exhauster, Oil Cooler etc and related equipments.
2. Lube oil in the main oil tank must be clean and free from debris.
3. Lube oil tank level > 100 mm.
4. Check that oil temperature in the tank must be 35°C.
5. Check and confirm that the vacuum of the main oil tank is satisfactory.
6. The power supply of all the electric accessories is correct.
7. The instrument air system has been put into operation and the supply air pressure to the
instrument and control system is normal.
8. The entire local indication instrument (Pressure Gauge, Temperature gauge, Differential
pressure gauge) are calibrated & functioning properly.
9. All isolation valves of pressure gauges, temperature gauges and temp. switches are open.
10. Check from the observation hole that the oil flow at the oil cooler shell side is normal.
11. Check and confirm that the lube oil system does not leak oil.
12. Valve Checks -
a) Check and confirm that all the drain valves close.
b) Operate the oil cooler changeover valve to select the operating oil
cooler. c) Close the oil cooler water chamber oil drain valve.
d) Open the water chamber vent valve.
e) Open the cooling water inlet/outlet valves.
f) When water overflows from the water chamber, close the water chamber vent valve.
13. Oil Cooler Changeover valve test -
a) Open the isolating valve on the oil cooler oil filling pipe.
b) Check from the observation hole that the oil flow at the two shell sides of the oil
cooler. c) Use the oil cooler changeover valve to change over the oil cooler.
d) Restore the oil cooler changeover valve to the original state.
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8. Initial Startup
1. Prior to start up; confirm that all the system start up checks are completed.
2. Start the main oil tank fume extractor & exhaust fan.
3. When the oil temperature in the oil tank is lower than 20O
C, turn off the cooling water of oil
cooler heat the oil to 35O
C.
4. When the Oil Temperature is 35°C (Maintained by Electric Heater in MOT) then Start Turbine
Oil pumps (TOP), & Operate the Oil system for circulation.
5. Due to oil circulation in the pipe line temperature of the oil will increase & when it is up to 38
°C, then put the oil cooler in service.
6. When the suction Pressure of Jacking Oil Pump is adequate i.e. … .then start the JOP & observe
the Discharge pressure. When the discharge pressure of JOP is adequate i.e. 18 MPa (180
kg/cm2
) then pressurized oil will lift up the journals of each bearing to the design height at least
0.02 mm min. & 0.1 mm max at each bearing.
7. Now, the turning gear can be operated, and the unit oil system is ready for start.
{The turning motor is not allowed to start until the bearing oil supply pressure exceeds 0.137 MPa
(1.37 kg/cm2) and jacking oil pump oil pressure exceeds 7 MPa (70 kg/cm2)}.
8. Start the MSP (Main Suction Pump), when the impulse starting speed of the unit is 2000 rpm,
stop the JOP.
9. During the unit speed up, MSP and TOP should operate normally to supply lubricating oil to
the unit.
10. When the Turbine speed is 2850 rpm then MOP will be in operation and observe the MOP
suction oil pressure before the turbine front bearing housing should be approx. 0.1 MPa (1
kg/cm2
).
11. With the rising of turbine main shaft speed MOP starts to deliver oil. The oil supply pump
will operate according to the oil flow of MOP so that the output oil pressure is low. This low
pressure will last till the Booster oil Pump (BOP) supplies oil together with the oil supply pump
and finally take the place of it.
12. The operation of the pumps should be monitored during the turbine main shaft rotating speed
rises to the rated speed till the final adjustment of the system is completed.
13. When the unit speed is 3000 rpm and the system oil pressure are stabilized
i.e a) MOP Suction pressure - 0.1 - 0.15 MPa (1 kg/cm2
1.5
kg/cm2
)
b) MOP discharge pressure - 1.205 MPa. (12.05 kg/cm
2
)
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9. c) Bearing Inlet pressure - 0.14 - 0.18 MPa. (1.4 kg/cm2
-1.8
kg/cm2
) Then first stop the MSP & after that stop the TOP.
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10. 14. When the MOP is in service & Lube Oil system pressure is stabilized. Then put the system in
AUTO MODE.(i.e. Turn control switch to AUTO for TOP, EOP & MSP)
Normal Operation (AUTO MODE)
1. When the turbine Speed is 3000 rpm, MOP (Discharge pressure-1.205Mpa) will supply the
lube oil to all the bearings. (Inlet bearing pressure is 0.14 - 0.18 MPa.).
2. In case of any abnormality following valves on the oil turbine should be adjusted and be
locked after adjustment.
• Power oil throttle valve.
• Bypass valve.
• Over flow valve
The above valves should be adjusted according to the following procedure at the rated turbine
speed before the TOP & Start up pump (MSP) are stopped.
a) Adjust the power throttle valve so that the main oil pump suction reaches the design value at
the front bearing housing of the steam turbine.
b) Check the bearing oil supply manifold and through overflow valve overflow amount.
c) At the same time adjust bypass valve and power oil throttle valve so that the bearing oil
supply manifold and overflow valve release amount reach the required value.
3. If the oil pressure drop to 0.115 Mpa or the outlet pressure of MOP is lower than 1.205 MPa,
it gives alarm & start TOP (Meanwhile Check for the cause of oil pressure drop)
4. When the Oil pressure still drops after TOP has started, EOP should start when Oil pressure
drops to 0.105MPa.
5. When the Suction pressure of MOP or Oil pressure drop is lower than 0.07MPa, the MSP
starts and Shutdown the Unit.
Checks during Operation
1. Check from the observation hole that all bearing oil drains are satisfactory.
2. Check and confirm that the bearing lube oil temperature is in the allowable range.
3. When the oil temperature in the Oil tank below 20°C, turn off the cooling water of Oil cooler &
heat the oil to 35°C by Electric heater.
(When the surface temp. is higher than 150°C, stop heating and if Temperature is decreased to
100°C, Restart heating)
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11. 4. Oil level at tank level should between the highest level (+100 mm) & lowest level (-100 mm).
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12. 5. Unit bearings requires inlet oil temperature of 40-45°C and normal return oil temperature of
less than 75°C. (Normally the water flow through the oil coolers should be adjusted according
to the oil temperature in the lube oil header to ensure bearing inlet oil temperature is in
accordance with requirement.)
Shutdown Condition
1. In case of normal or emergency shutdown (hand trip or unit trip), the auxiliary oil pump (TOP) &
startup oil pump (MSP) must start automatically before the turbine decelerates to 2850 rpm.
2. Shaft Jacking device (JOP) starts when the turbine decelerates to 2000 rpm.
3. In case of Auxiliary pump failure, EOP should be interlocked to ensure safe shutdown.
4. Stop the Jacking oil pump (JOP) and TOP oil pump only after the turning gear stops.
5. After check, stop the turning gear and then stop the jacking oil pump and finally stop the
TOP Pump.
6. Confirm that emergency oil pump can start automatically.
7. Stop the emergency oil pump.
8. Close the oil cooler cooling water inlet and outlet valves.
9. Stop the turbine oil purifier.
10. If necessary, stop the oil tank fume extractor.
Procedure identification
Procedure Title: Standard Operating Procedure of Turbine Lube Oil system
Prepared by: Ajit Kumar
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