Hydrogen Seal Oil

Question 1

What do the following valves do in the HSS?

PCV-107
PCV-108
PCV-109
PCV-28

Answer 1

107-maintains air side seal oil Press>H2 Press by 12 psid
108-maintains b/u air side seal oil Press>H2 Press by 8 psid
109/28-maintains H2 side seal oil equal to air side seal oil

Question 2

What is the minimum oil pressure required to seal H2 in the Generator ?

Answer 2

3 psig > H2 pressure

Question 3

Why is the air side seal oil supplied to two different locations on the seal?

Answer 3

Seal- to seal air out
Side of floating seal-ensures H2 side seal oil doesn’t mix with air side on back of seal (minimize H2 consumption and maintain purity)

Question 4

What will start the air side seal oil back up pump?

Answer 4

Pressure switch senses that seal oil pressure lowers to 5 psig > H2 pressure

Take control switch to test (bleeds Press switch)

Question 5

How will the following valves respond if:

Air side seal oil Press to low (PCV-107)

Air side seal oil Press to low (PCV-108)

H2 side seal oil Press > air side (PCV-109)

H2 side seal oil Press < air side (PCV-28)

Answer 5

107- close => less recirc flow, more pressure

108- open => more flow, more pressure

109- close => less H2 side flow, less pressure

28- open => more H2 side flow, more pressure

Question 6

Why does HSS have two tanks that receive volume from deforming tanks instead of one?

Answer 6

Receiver tank- receives inventory so splashing doesn’t occur on float valves and provides NPSH to H2 side seal oil pump

Drain reg tank- maintains inventory control by float valves

Question 7

Precautions and limitations for HSS

Answer 7

Generator gas pressure determined by available HSS press, if next available is LP bearing oil, generator Press must be reduced to 2 psig

If HSS is S/d, generator shall be at rest