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example hydrogen seal oil presentation
- 1. Unit 4 HydrogenSeal Oil Stephen Ford Simulator / Training Instructor MEC
- 2. • Please lookaround 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 H2Seal 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.
- 5. • In accordancewith 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 accordancewith 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 accordancewith 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 accordancewith 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 H2gas 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 isHydrogen 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.
- 12. Oil comes fromBearing Lube Oil Header 13 About 24 Gallons per Inch of level in the Vacuum Tank
- 13. Level is controlledby 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 levellowers The float moved down Due to the location of the pivot point This opens the valve
- 15. Air and moistureare vented to atmosphere as these would effect H2 Purity 16
- 16. Continuous Moisture removalvia 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 siteglass and remove water via M40_1 18
- 18. • There ismoisture 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 VacuumTank through MSOP 20
- 20. MSOP 21 The Main SealOil 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 OilPump 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 105Psig at the discharge of the MSOP Excess oil is returned to the Vacuum Tank
- 23. • Which oneof 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 MaintainsSeal 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 Removessmall 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 VacuumPump 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 VacuumPump 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 FlowPath 29
- 29. ESOP 30 125V DC PP#4A Circuitbreaker 4A
- 30. Flow Path NOPumps ( Supplied only from Bearing Oil at Reduced Pressure) 32
- 31. • Normal flowpath 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 theseal. This flow also maintains an Oil Film between the shaft and the seal 34 Air Side Hydrogen Side Bearing Oil
- 33. • The oilflows 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 ahydrogen 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 Dividedinto 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 aseal 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) DetrainingSection 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 liquidscould 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 OpenH2 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 agroup 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 FloatTrap 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 FloatTrap (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 RSOPnormally 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 ofESOP 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 OpenVacuum 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 forStuck 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 ClosedVacuum 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 failsclosed • 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 failsopen • 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 hydrogenseal 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 spillarea 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 ( OilMist and Results) 58
- 57. Vented H2 toallow for securing H2 Seal Oil System 59
- 58. • With theleak 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 H2Seal 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 functionof 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 ofthe 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 Unitis 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 ofthe 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 Unitis 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 Unitis 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 HighestPressure 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 backto 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.
Editor's Notes
- #3Â H2 is used because it is lighter than air resulting in less windage losses and has a better thermal conductivity than air.
- #11Â H2 is used because it is lighter than air resulting in less windage losses and has a better thermal conductivity than air.
- #25Â Answer A is wrong because the spring for closing is compressed not tensioned upon opening of the safety. C is wrong because both can be ganged. D is wrong because blowdown can be set by adjusting the parameters of the valve