H2 Seal Oil

Question 1

What is the Purpose of the Hydrogen Seal Oil System?

Answer 1

To seal the generator shaft against H2 Leakage

Question 2

What is the Recirc Seal Oil Pump purpose and flow patch?

Answer 2

It takes suction off the vacuum tank and returns to spargers in same time. Helps to remove entrained H2 gas

Question 3

What normally provides oil to the vacuum tanke?

Answer 3

Turbine Bearing Oil Header

Question 4

What is the normal Operational Flow Path for the H2 Seal Oil?

Answer 4

Main Seal Oil Pump takes suction off Vacuum Tank. Pumps ~60gpm to PCV then generator bearings to perform sealing
DP control valve maintains oil pressure ~8-9psig above H2 pressure

Question 5

Where do the inboard Generator Seal H2 Oil drain to?

Answer 5

H2 Seal Drain Enlargement Tank - This drains to float trap then to Air Detraining Tank and back to Turbine Lube Oil Reservoir

Question 6

Where does the outboard Generator Seal H2 Oil drain to?

Answer 6

To the air detraining tank then Turbine Bearing Return Header

Question 7

Where does the Generator MSOP send oil?

Answer 7

To the PCV then to the Generator Seal. A small amount of excess flow goes back to vacuum tank RSOP discharge

Question 8

What is the purpose of the H2 Seal Vacuum Pump and flow path?

Answer 8

Takes suction from vacuum tank to maintain vacuum near 28”Hg vacuum. Discharges to oil separator tank where water drains out and H2 vents to roof

Question 9

What are the power supplies for the H2 Pumps:
Vacuum Pump?
MSOP?
RSOP?
ESOP?

Answer 9

Vacuum Pump: MCC 28-2
MSOP - MCC 28-2
RSOP - MCC 28-2 (same motor as MSOP)
ESOP - 250vdc TB MCC 2

Question 10

What is the purpose of the ESOP?

Answer 10

Takes suction directly from breaing header oil header (inlet to vacuum tank) and discharges to DP control valve if MSOP unable to do so.

Question 11

When does the ESOP start?

Answer 11

Will start on an 80# discharge pressure of MSOP (normally ~100#) - this is when MSOP trips
Also has auto start P/B test ESOP auto start feature w/out tripping MSOP

Question 12

When does the MSOP trip?

Answer 12

80# discharge pressure

Question 13

What is the purpose of the DP Control Valve? What is it’s setpoitn?

Answer 13

Ensures seal oil pressure is greater than Generator Gas Pressure by ~8-9psig to minimize leakage.

Doesn’t use instrument air or control power - is a diaphragm with oil from different points on either side to maintain the DP

Question 14

What happens if the Float Trap Fails?

Answer 14

If fails closed, oil backs up in Drain Enlargement Tank and spills into LIQUID DETECTOR - alarm on liquid detector.

Question 15

What kind of pump is the MSOP?

Answer 15

Positive Displacement

Question 16

What is the purpose of the Hydrogen Seal Drain Enlargment Tank?

Answer 16

Takes oil from inboard Generator Seals - used to separate entrained hydrogen from the oil.

Question 17

What exists between the enlargement tank and Float Trip to prevent Hydrogen from flowing back to turbine oil system?

Answer 17

Loop Seals

Question 18

What is the Float Trap?

Answer 18

Used to provide a seal to prevent escape of H2 - separates the region which is at Generator Pressure from region at atmospheric

Question 19

What is the Air Detrainment Section?

Answer 19

Used to detrain air from il before returnign to turbine oil tank

Question 20

What happens on a loss of the MSOP?

Answer 20

ESOP starts at ~80psig.
H2 purity decreases since no recirc through deaeration process in vacuum tank
Vacuum tank inlet isolation valve is shut to prevent vacuum tank flooding

Question 21

What happens on loss of all Seal Oil Pumps?

Answer 21

Bearing Header bypasses seal oil pumps via check vlv and seal oil pressure drops to bearing oil header (~30psig).
H2 blows past seals until generator pressure drops to ~23psig
Vacuum tank inlet isolation vlv and MSOP discharge check vlv shut to avoid flooding vacuum tank
Bypass vlv around DP control vlv and filter opened to minimize pressure drop.
H2 SHOULD BE Isolated as an explosive mixture will exist outboard of the seals