Main Turbine Lube Oil Flashcards
State the purpose of the main turbine lube oil system.
1) Provide lube oil to the main turbine and generator bearings
2) provide lube oil to the bearing lift oil pumps
3) supply oil to the generator seal oil system
How is the main shaft oil pump driven?
It’s mounted on and powered by the main turbine shaft.
Which pump is normally used to supply oil to the suction of the main shaft oil pump?
the booster oil pump that is located in the lube oil reservoir.
What drives the booster oil pump?
Oil from the discharge of the main shaft oil pump.
What do the booster nozzle and baffler valves do?
Reduce the main shaft oil pump discharge pressure down from 235psig to 190 psig to drive the oil driven turbine that turns the booster oil pump shaft.
What does the motor suction pump do?
it supplies oil to the suction of the main shaft oil pump until the turbine shaft reaches 90% of rated speed at which time the main shaft oil pump discharge pressure is high enough to run the booster oil pump turbine.
What pressure does the oil header relief valve maintain at turbine centerline?
25psig regardless of system dips or surges
What supplies cooling water to the main turbine lube oil coolers?
TC
What is the power supply for the emergency lube oil pump?
NK
When is the turning gear oil pump used?
it provides bearing oil to the turbine’s bearings while the turbine is on the turning gear or when it’s coming up to speed
What will cause the turning gear oil pump to start when it’s in Auto?
Main shaft oil discharge pressure low at 190psig or bearing oil pressure low at 15 psig
Where can the test of the auto start function for the turning gear oil pump be performed from?
Two buttons in the control room
Two buttons at the main lube oil reservoir
What pump would be used to supply oil to the turbine if there were a turbine trip and a loss of off site power?
The emergency lube oil pump that is powered by NK would be used.
What causes the emergency lube oil pump to start if it’s in AUTO?
Main shaft lube oil pressure low at 180psig in CONJUNCTION with Turning gear oil pump low discharge pressure at 15 psig.
Low voltage on the power supply to the turning gear oil pump will also auto start the emergency lube oil pump.
Where are the main lube oil coolers?
they are mounted vertically inside the lube oil reservoir with a portion sticking out of the reservoir.
How is main lube oil temperature maintained in band?
automatically by a valve on the cooler TC water outlet throttling flow.
How can an operator tell if a lube oil cooler is full of oil prior to placing it in service?
By opening the cooler inlet bypass valve for the cooler you want to place on service and observing oil flow from a constant vent on the cooler that can be seen by lifting a hatch on the reservoir.
What does the vapor extractor do?
pulls air, oil vapor, hydrogen, and moisture from the main lube oil reservoir through a mist eliminator. This causes some flow of cool air to move through the shaft bearing oil deflectors and prevents the accumulation and carbonization of oil between the deflector teeth and on the turbine shaft.
What does the mist eliminator do?
it uses fiberglass filters and a pressure blower to remove oil from the vapor and returns the oil to the OW system.
Where is the vapor extractor operated from?
the handswitch at the vapor extractor outside of the turbine building 176’
Why are the bearing lift oil pumps used?
to reduce torque requirements of the turning gear motor.
How many lift oil pumps are there and where are they located?
8 and they are located by the bearings that they supply oil to.
How much does the oil lift pump lift the rotor?
2-5 mils
When will the oil lift pumps start in Auto?
when the turning gear oil pump discharge pressure is at least 10psig
Which lift oil pumps are interlocked to shut off if the turning gear motor is running and rotor speed < 2 RPM?
7 and #10 to provide sufficient load to stop the turning gear from disengaging.
Describe the supply header piping that is located in the vicinity of hot turbine parts.
The supply header piping is enclosed in the drain header piping in case there is a rupture, the oil will spray into the drain piping and back to the sump.
In regards to main turbine lube oil, what will cause a turbine trip?
main shaft oil pump discharge pressure less than 100 psig OR bearing header oil pressure less than 12 psig.
What are the temperature limits for the journal bearings? the thrust bearing?
journal bearings- NTE 240F
Thrust bearing- NTE 190F
What should you do with the turning gear if the lube oil temperature exceeds 110F?
ensure the turning gear is in the “pull to lock” position.
What should be done is lube oil is < 102F?
place the turbine on the turning gear.
