The document discusses the hydrogen seal oil system on a generator. It describes the purpose of the system as preventing hydrogen gas from escaping along the generator shaft by forming an oil film between the shaft and seal ring. It outlines the normal flow path of oil through the main seal oil pump and other components like the vacuum tank, emergency seal oil pump, and detraining tanks. It also discusses potential failures of components like pumps and the float trap, and the appropriate operator actions to take in response.

1. Unit 4 Hydrogen Seal Oil
Stephen Ford
Simulator / Training Instructor
MEC

2. • Please look around the room and verify there
are no hazards present
• Please place cell phones on vibrate or off
• Please keep snacking and drink areas
presentable
• Please refrain from side bar conversations so
we can all learn from questions
Training 2 Minute Drill
3

3. • Generator H2 Seal Oil is vital to plant operation
• Loss of H2 Seal Oil can result in an explosive
atmosphere in the plant
• Prompt operator action on component failures
can minimize equipment damage and
personnel safety
• The following is an example of damage caused
Introduction
4

4. Springfield Hydrogen Explosion
5

5. • In accordance with 04-GOS-SD STATE or
SUMMARIZE the following to an accuracy of
80% on a multiple choice examination.
– Purpose of the Generator H2 Seal Oil System
– The Flow Path of the following:
• MSOP (Main Seal Oil Pump)
• ESOP (Emergency Seal Oil Pump)
• Bearing Oil (All Pumps Off)
• Hydrogen Detraining Tank and Aux Detraining Tank
• Bearing Header
Objectives
6

6. • In accordance with 04-GOS-SD STATE or
SUMMARIZE the following
– Function of components
• MSOP
• SOVP (Seal Oil Vacuum Pump)
• Separator Tank
• ESOP
• RSOP
• Relief Valve
Objectives
7

7. • In accordance with 04-GOS-SD STATE or
SUMMARIZE the following
– Function of components
• Pressure Regulating Valve
• Strainers
• Seals
• Aux and Hydrogen Detraining tanks
• Liquid Detector
• Float Trap H-58
Objectives
8

8. • In accordance with 04-GOS-SD STATE or
SUMMARIZE the following
– Abnormal actions
• Vacuum Tank float fails open / closed
• Loss of MSOP
• Loss of MSOP and ESOP
• Bypassing the Float Trap
• Hi Liquid Detector Level
– Discuss the Unit 3 SER on H2 Seal Oil Cuno Failure
causing a large oil leak and how operator actions helped
Objectives
9

9. • Prevents H2 gas from escaping along the
Generator Shaft
• Forms a film between the Generator Shaft and
the Seal Ring
• Keeps Hydrogen in and Air out
• The Hydrogen is used to cool the generator
components
Function
10

10. • Why is Hydrogen used to cool the Generator
instead of air?
– Thermal Conductivity 7-10 times better than air
– Less Dense than air
– Therefore a Hydrogen Cooled Generator is smaller and
less expensive than an Air Cooled Generator
• Why not use Helium as it is an inert gas?
– Helium is so expensive the cost prevented it’s use even
Question
11

11. Hydrogen Seal Oil
12

12. Oil comes from Bearing Lube Oil Header
13
About 24 Gallons per Inch of level in the Vacuum Tank

13. Level is controlled by a float valve
14
Oil comes in via H41_1 as controlled by H10_1 float
If level in the vacuum tank lowers the float adjusts to allow more flow into the tank

14. Float Valve
15
As level lowers
The float moved down
Due to the location of the
pivot point
This opens the valve

15. Air and moisture are vented to
atmosphere as these would effect H2
Purity
16

16. Continuous Moisture removal via Gravity
Drain
17
The separator tank is
baffled to aid in moisture
removal
The water flows to the
bottom as it is heavier
than the oil to the Floor
Drain
This is also checked by
the EO on rounds and
drained manually if
needed via H40_1
This oil should be
changed monthly

17. Monitor via site glass and remove water
via M40_1
18

18. • There is moisture in the effluent going to the vent
• On a very cold day at a past power plant
• The moisture on the vent on the roof froze
• Preventing flow from the separator tank
• Evidenced by extra pressure when you drain the water from
the separator tank or pressure in the oil addition line
• Long term H2 purity could be effected
Operational Experience Lesson
19

19. Flow via Vacuum Tank through MSOP
20

20. MSOP
21
The Main Seal Oil Pump
(MSOP)
Takes a suction from the
Vacuum Tank
Goes through the PRV
Onward to the Generator
Shaft Seals
Powered from MCC-4K2

21. Recirculation Seal Oil Pump
22
Recirculates oil from
Vacuum tank through the
Spray Header
Powered from MCC-4A1
Aids in removal of air
The Recirculation Sprays
atomize the oil thereby
aiding in the removal of
air and moisture

22. Relief Valve
23
Maintains 105 Psig at the
discharge of the MSOP
Excess oil is returned to
the Vacuum Tank

23. • Which one of the following is a difference between a typical
relief valve and a typical safety valve?
A. The actuator closing spring on a relief valve is in a compressed state
whereas the actuator closing spring on a safety valve acts in tension.
B. A relief valve gradually opens as pressure increases above the setpoint
pressure whereas a safety valve pops open at the setpoint pressure.
C. Relief valves are capable of being gagged whereas safety valves are
not.
D. The blowdown of a relief valve is greater than the blowdown of a safety
valve.
Fundamentals Review Question
24

24. Pressure Regulating Valve
25
Maintains Seal Oil
Pressure
Approximately 8 Psig
GREATER than the
Hydrogen in the
Generator
The top of the actuator is
Generator H2 Pressure
the lower tap is Seal Oil
Pressure

25. Strainer / Filter
26
Removes small
particulate matter
One in service
One in standby
Upon high DP place the
standby filter in service
And clean the dirty filter

26. Seal Oil Vacuum Pump
27
Maintains approximately
0.5 PSIA in the Vacuum
Tank
The separator tank is on
top of the pump
This tank is baffled to aid
in removing oil and
moisture from the gases
discharged from the
pump

27. Seal Oil Vacuum Pump Separator Tank
28
There is a site glass
There is a manual drain
to drain accumulated
moisture
Oil can also be added

28. Emergency Pump Flow Path
29

29. ESOP
30
125V DC PP#4A
Circuit breaker 4A

30. Flow Path NO Pumps ( Supplied only
from Bearing Oil at Reduced Pressure)
32

31. • Normal flow path through the MSOP from the Vacuum Tank
through the Seals
• If the MSOP loses power the Emergency Seal Oil Pump
Bypasses the MSOP and Vacuum Tank and still goes to the
seals
• If the MSOP and ESOP are lost Bearing Oil simply bypasses
both of those pumps are supplies seals at a reduced pressure
(25 Psig at Turbine Centerline plus the Pressure due to the
difference in height from Turbine to Seal Oil skid)
• Will have to vent H2 to stay below this pressure
Here is how I like to think about this
33

32. Flow through the seal. This flow also maintains an Oil Film
between the shaft and the seal
34
Air Side Hydrogen Side
Bearing Oil

33. • The oil flows into the segmented seal rings.
• Part of the oil flows into the “hydrogen side” of the
generator, the other part flows to the “air side” of the
generator.
• The oil between the seal ring and the rotating shaft
lubricates the seal rings, and provides a barrier to
stop hydrogen from leaking from the generator
through the seal.
Seal
35

34. There is a hydrogen side and an air side.
36
The Hydrogen side (RED)
drains to the Hydrogen
Detraining Tank
The Air side (YELLOW)
drains to the Aux
Detraining Tank
Bearing Oil (Blue Circle)
Most of the H2 released
from the H2 detraining
section goes back to the
generator
The H2 released from the
Aux (air) detraining
section is lost to
atmosphere via the vent

35. Hydrogen Detraining Section
37
Divided into two equal
sections connected by a
loop seal
Provides circulation due
to slight differences in fan
pressures at each end of
the rotor
The larger surface area
provides for Hydrogen
bubbles to be released
It also permits oil to drain
without the oil mist being
recirculated in the
generator

36. Float Trap
38
Maintains a seal between
the Hydrogen in the
Generator and the Oil
returning to the Bearing
Oil Drain
When level is LOW the
float valve is CLOSED
preventing Hydrogen from
passing through the
system
As the oil passes to the
Aux Detraining section
the dissolved H2 is
vented via the
enlargement in the
bearing drain line

37. Aux (Air) Detraining Section
39
H2 Seal oil from the Air
side of the generator
seals is routed to the Aux
Detraining Section (Air)
This is why the Vapor
Extractor on the Turbine
Lube Oil Reservoir is so
important
Any H2 not removed via
the Drain Enlargements is
removed via the Vapor
Extractor

38. Liquid Detector
40
Four liquids could be found in the liquid detector
Stator Cooling, Hydrogen Cooling, Seal Oil and Bearing Oil
Hydrogen Pressure should normally be greater than Stator or Hydrogen Cooling

39. • Stuck Open H2 Float Trap
• As a group discuss the consequences of the
H2 Float Trap sticking open
– Generator H2 Pressure lowers quickly
– Must bypass the float trap and maintain in manual
– Check Generator Capability Curve
– Reduce Load as needed
Failures and actions
41

40. • As a group determine Human Performance
Tools that could be used while Bypassing the
Float Trap.
– Procedure Adherence
– Circle slash placekeeping
– STAR ( verifying the response )
– First Check from EO in the field ( Correct Unit etc.)
– Peer Check in the field if available
– Proper narrative log entry
– Proper notifications
–
Human Performance Review
42

41. • H2 Float Trap Stuck Closed
• As a group discuss the consequences of the
H2 Float Trap sticking closed
– Oil backs up into the detraining section
– Once it reaches the overflow it goes to the liquid detector
– Bypass the H2 Float Trap
Failures and actions
43

42. Bypassing the Float Trap
(Procedure 04-GOS-OI)
If the Float Trap must be
bypassed
Isolate the Float Trap
Throttle open the Bypass
H05_1
Then the site glass must
be valved in so you can
see level
Maintain level in middle of
site glass

43. • MSOP failure
• As a group discuss the consequences on a
loss of the MSOP
– Emergency Seal Oil Pump Auto Starts
– The Vacuum Tank is bypassed
– H2 Purity will lower
– Feed and Bleed H2
Failures and actions
45

44. • RSOP failure
• As a group discuss the consequences on a
loss of the RSOP
– This is kind of interesting because the relief valve for the
MSOP has now lost the backpressure that it had while the
RSOP was on and therefore relieves at a lower pressure
– This will likely be low enough to start the ESOP
– In this case you will see the MSOP and ESOP on with the
RSOP off (Feed and Bleed for purity)
Failures and actions
46

45. Relief Valve
47
The RSOP normally
maintains a backpressure
on the relief valve
Without the RSOP the
MSOP will overcome the
relief valve pressure at a
lower setpoint
This will likely drop
pressure enough that the
ESOP will start thus
bypassing the vacuum
tank
Long term purity is
maintained by feed and
bleed

46. • Failure of ESOP and MSOP
• As a group discuss the consequences on a
loss of the ESOP and MSOP
– The Bearing Oil Header supplies Seal Oil at a
substantially reduced pressure
– Vent H2 to below Seal Oil Pressure
– Lower Load to stay below Generator Capability Curve
Failures and actions
48

47. • Stuck Open Vacuum Tank Float Valve
• As a group discuss the consequences of the
Vacuum Tank Float Valve Sticking Open
– The Vacuum Tank Level rises
– Vacuum degrades in the Vacuum Tank
– Shut off the SOVP to prevent damage
– Shut valve H09-1 to stop flow to the Vacuum Tank
– Start the ESOP
• There was a plant that actually had oil coming out of the vent
Failures and actions
49

48. Lesson Learned for Stuck Open Float
Valve
50
The float valve stuck open and H09-1 was never shut
Oil eventually filled the Vacuum Tank and about 40 Gallons went through the vent
to the roof

49. • Stuck Closed Vacuum Tank Float Valve
• As a group discuss the consequences of the
Vacuum Tank Float Valve Sticking Closed
– MSOP trips
– ESOP starts
– Vacuum Tank is Bypassed
– Feed and Bleed to maintain purity
Failures and actions
51

50. • PRV fails closed
• As a group discuss the consequences of the
PRV sticking closed
– Seal oil pressure drops
– Open PRV bypass to establish 8 Psid
Failures and actions
52

51. • PRV fails open
• As a group discuss the consequences of the
PRV failing open
– Seal oil pressure rises
– One could throttle the PRV inlet or outlet to maintain
approximately 8 Psid
– Or fully valve out the PRV and control on the bypass
Failures and actions
53

52. • Strainer plugging
• As a group discuss the consequences of the
Strainer plugging
– High DP noted on strainer
– PRV will have to open more to maintain D/P
– Place online the clean strainer
– Clean the dirty strainer
Failures and actions
54

53. • On Friday, October 26, 2012 at approximately 1440, a
Neal 3 equipment operator was performing routine
filter cleaning of the hydrogen seal oil Cuno filter by
turning the spindle handle located on top of the filter
canister.
• While turning the handle, the spindle’s retainer came
loose and the spindle came out the top of the filter.
• Since the filter internals were pressurized with oil, a
large flow of seal oil sprayed out the top of the filter.
SER
55

54. • The hydrogen seal pumps were left in service while the
generator hydrogen pressure was being manually vented.
• Because of the large amount of oil spray, (See pictures at end
of report) turbine oil had to be transferred from the batch tank
to the turbine lube oil tank to maintain adequate oil flow to the
turbine bearings.
• Once the hydrogen was at an acceptable pressure, the
hydrogen seal oil system was removed from service and the
Cuno filter was valve out to stop the oil leak.
SER ( Had to Vent H2)
56

55. • The spill area was cleaned sufficiently to allow repairs to be
made to the Cuno filter.
• When the Cuno filter was opened, it was discovered that the
internal components had been previously removed.
• Since the hydrogen seal oil system has parallel cartridge filters
located downstream of the Cuno filter, the Cuno filter was
returned to service without internal components. Pipe plugs
were installed in place of the spindles.
SER
57

56. SER ( Oil Mist and Results)
58

57. Vented H2 to allow for securing H2 Seal
Oil System
59

58. • With the leak from the system H2 Seal Oil could no longer
maintain seal pressure without causing a large oil leak
• By venting H2 the pressure is reduced so it does not blow by
the seals and into the atmosphere which would create an
explosive condition
• Have shift supervisors discuss the event with their crews.
Emphasize how actions taken by the on-duty crew prevented
events from occurring, which could have been much more
severe
• The operators performed very well during this event
SER
60

59. • Generator H2 Seal Oil maintains the Hydrogen
in the Generator
• Any malfunction which lowers Seal Oil
Pressure below the Hydrogen Pressure must
be quickly addressed
• Normally by venting hydrogen and reducing
load
Summary
61

60. • The function of the Generator Seal Oil System
is to maintain (_____) in the generator and an
Oil (_____) between the Shaft and the Seal
Ring.
A. CO2, Mist
B. Nitrogen, Spray
C. Air, Blanket
D. Hydrogen, Film
Review Questions
62

61. • Which of the following is a correct order
components for the normal Generator Seal
flow path?
A. PRV, Seals, Strainer, MSOP
B. Seals, Strainer, PRV, MSOP
C. MSOP, PRV, Strainer, Seals
D. Strainer, PRV, MSOP, Seals
Review Questions
63

62. • The Unit is at 100% power when a trip of the
MSOP occurs with a failure of the ESOP to
start automatically or manually. The Unit
Operator should direct (Venting / Adding)
Hydrogen and (Raise / Reduce) Load?
A. Venting / Raise
B. Venting / Reduce
C. Adding / Raise
D. Adding / Reduce
Review Questions
64

63. • Which of the following conditions could result
in a liquid detector high level alarm?
A. Stuck open Vacuum Tank float valve
B. Failure of the MSOP
C. H2 Float Trap stuck closed
D. Plugged strainers
Review Questions
65

64. • The Unit is at 100% power. The H2 Seal Oil
PRV has failed closed. The Unit Operator will
give the following direction to the Equipment
Operator.
A. Bypass the strainers
B. Add Hydrogen
C. Start the ESOP
D. Bypass the PRV
Review Questions
66

65. • The Unit is at 100% power when the MSOP
trips. All automatic actions have actuated
properly. What is the next concern for the Unit
as it pertains to the Generator and the
associated Seal Oil system
A. Reduced pressure to the Seals
B. Degrading H2 Purity
C. Overheating the ESOP
D. Strainer plugging
Review Questions
67

66. • From Highest Pressure to Lowest list the
following in the proper order. ( Generator Gas,
Stator Cooling, H2 Seal Oil).
1.Hydrogen Seal Oil
2.Generator Gas
3.Stator Cooling
Review Questions
68

67. • Go back to the beginning and review the
Knowledge Objectives
• After the review ask for any questions
• Follow up with any questions not answered
during class promptly
Knowledge Objective Review
69

68. 70