Main Turbine & MTLO Flashcards
Flow path from MSS to condenser
- equalized steam header - through 1 of 4 stop valves, 1 of 4 control valves - enters HP turbine (center) each lead has own quadrant nozzle (partial arc admission) - exits HP turbine –> MSR’s (1 of 6) - Removes moisture and super heats (~120 deg) - through reheat stop valves, intercept valves - enters LP turbines (1 of 3) - exits main condensor
How do you isolate the Trip pilot valve on the stop valve? What is purpose of valve? How do you prevent leakage from CV and stop cooldown via Trip pilot valve?
You latch the turbine, EH fluid closes pilot valve to condenser - steam leakage along shaft builds up pressure in void - forces assembly to side sealing any further leakage To seal shaft of stop valve (prevent leakage) Don’t let SV open when latch turbine, shut “turbine SV bypass valve air supply” before latching turbine=> won’t bypass around stop valve, stop valve can’t open against full d/p
1st stage impulse pressure instruments What is normal 1st stage Press @ 100% pwr?
PT-505, 505A, 506, 506A & PT-8 543 psig
What valves reposition when you latch the turbine?
Stop valves open Intercept valves open Reheat stop valves open Control valves stay shut
What valves will shut (then reopen) on a load rejection? What valves shut on a turbine Trip?
Intercept valves Control valves CV, SV, IV, RSV……..all
What bearings have lift oil supplied to them? What is pressure supplied?
3-8, 3-7 from bearing lift oil pump 8 has its own dedicated lift oil pump 1500 psig
Describe LP shaft seals
Vacuum inside turbine casing, atm outside - gland sealing steam (8#)-> labyrinth seals - atm side has suction to GSC (15” vac), sucks steam and air => no air in - casing side, 8# steam flows in => no steam out
What is difference between LP and HP gland sealing steam?
HP GSS has additional steam inlet to labyrinth Seals. Between 8# GSS and casing is cylinder heating steam supply that is maintained 5# > HP turbine exhaust At high powers(ie high Press cylinder heating steam) steam will actually flow backwards through GSS from cylinder heating steam
What will happen when turbine reaches 0 rpm and turning gear is in automatic? Why is this important?
Turning gear will automatically engage and start The turbine rotor can bow due to its own enormous weight or due to uneven heating
Main turbine AC bearing oil pump:
P.S.
Auto start signals
Indication
- 1G
- Low hdr Press < 11.5 psig (PS-106)
- Red light turns on Pdisch > 26 psig (PS-358)
Main turbine DC emergency oil pump:
P.S.
Auto starts
Indications
250 vdc mcc, 121
- Low hdr Press < 10 psig (PS-33)(turn gr suct)
- Low hdr Press < 10 psig (PS-327)(Trip block)
- bus G UV & both MG output bkrs open
Red light on when Pdisch > 26 psig
Main turbine HP seal oil b/u pump P.S. Auto starts
15E Low hdr Press < 13 psig (PS-105)
Main turbine lube oil Bearing lift oil pump auto start / auto stop Bearing #8 lift oil pump auto start
8…when BLOP starts & Psuct > 3 psig (PS-601)
Start
- Turbine speed < 600 rpm &
- Oil Press @ turn gear > 4.5 psig (PS-31)
Stop
- Turbine speed > 600 rpm Or
- Oil press @ turn gear < 3 psig
Where various stages of extraction steam go?
HP - 3rd stage-> first stage reheat MSR - 7th stage-> #2 fw heater LP (9th=2nd LP stage) - 9th stage-> #3 fw heater - 11th stage-> #4 fw heater - 12th stage-> #5 fw heater - 13th stage-> #6 fw heater
What does main oil pump provide oil to?
LP H2 seal oil b/u MOP suction HP H2 seal oil b/u HP oil to thrust bearing wear/Trip Auto stop oil Turbine bearings Lift oil pumps
