Dry Gas Seal Presentation


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Dry Gas Seal Presentation

  1. 1. John Crane Gas SealsGas seals and their application for maximum reliability
  2. 2. John Crane Turbomachinery Products & Operation
  3. 3. DGS Application RangeJohn Crane DGSOperating Range Temp: -140 to +315°C Pressure: to 450 Barg Speed: to 200m/s Shaft: to 330mm
  4. 4. Type 28AT Seal Design FeaturesCompliant stationary face design providing• maximum flexibility• Optimum slow roll capability Logarithmic spiral or bi-directional design. Tungsten carbide or silicon carbide rotating seat
  5. 5. Type 28 AT for duties to 82 bar Carbon seal faces Elastomeric ‘O’ Ring Secondary seal
  6. 6. Type 28 XP for duties to 200 bar Carbon seal faces Keyed Balance dia. polymer
  7. 7. Type 28 EXP for duties to 350 bar Cranite seal faces ADC Balance dia. polymer
  8. 8. John Crane Range of Standard gas seals 350 John Crane T28 300 Gas Seal Standard Application EnvelopeMax Pressure (barg) - Static or Dynamic 250 Re-injection Duties Type 28 EXP 200 150 100 Core business 50 Type 28 XP 0 High Speed LNG type Duties 50 100 150 200 250 300 Shaft Diameter (mm) Type 28 ATJohn Crane dominate High Technology Market sectors
  9. 9. Type 82 Barrier seal Benefits Proven / reliable design >15 years field experience on a wide range of applications Excellent protection against Oil ingress into DGS limited N2 Consumption No explosive mixture risk No process gas to bearing housing Environmentally Friendly
  10. 10. Control Panels & SEPro SystemsComplex Gas Seal control panel SEPro system for BP& booster for BP Horn Mountain
  11. 11. Gas seal performance progress 450 400 em u ad nd PQ Ta & 350 X C nit e P EX A D ra 300 )Pressure (Bar) (C e ipl Tr 250 XP 200 em T and XP 150 ple Tr i AT 100 m nde 50 Ta AT 0 1985 1990 1995 2000 2005
  12. 12. John Crane Turbomachinery Seal design for maximum reliability
  13. 13. John Crane Turbomachinery System design for maximum reliability80% of seals fail prematurely because of contamination
  14. 14. Ensure the gas is clean and dryEXTERNAL GAS  For extended reliability FILTER Filtered Process Gas clean / dry seal gas is the MODULE MOST importantPROCESS GAS • Gas should be filtered FI FI to around 1 micron • Coalescing filters can be used to dry the gas • Heaters can be used to provide superheat • Heat tracing should be used to prevent heat loss • SEPro type systems can be used to provide Process Gas static gas flow
  15. 15. Phase Diagrams 180  Check adiabatic expansion 160 AF 15256 Gas Composition  Check hydrate formation 140 120Pressure (bar) 100 80 60 40 20 0 -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 Temperature (C) dew line bubble line Adiabatic Expansion Hydrate Curve (1% H2O)
  16. 16. Using a thermocouple to measure sealtemp Specify a Thermocouple to monitor seal temp OEM will need to provide exit gland •End User in Alaska •325 bar working pressure •5.687” Seal on Suction End •350 bar max pressure •6.929” seal On Discharge •11753 rpm •Reinjection duty with H2S •Operating since August 2000
  17. 17. Field Gas Analysis- Plot operating conditions 180 160 AF 15254 -59°C Dew Point 140 120 Pressure (bar) 100 80 60 40 20 0 -200 -150 -100 -50 0 50 100 150 Temperature (C) dew line bubble line Adiabatic Expansion Hydrate Curve Gas from Skid Seal Gas DE Seal Gas NDE
  18. 18. Field Gas Analysis- Plot operating conditions 180 Predicted worst case expansion line 160 AF 15254 -59°C Dew Point 140 Measured operating points from Data capture system 120 Pressure (bar) 100 Actual worst case 80 expansion line passing through liquid region 60 40 20 0 -200 -150 -100 -50 0 50 100 150 Temperature (C) dew line bubble line Adiabatic Expansion Hydrate Curve Gas from Skid Seal Gas DE Seal Gas NDE
  19. 19. Review gas properties Element Wt% CK 09.62 OK 09.40White deposits found across IB seal facesCaused seat and face to stick together AlK 00.11 SiK 00.32 SK 80.55 Area analysed White deposits identified as deposition of elemental sulphur Clear evidence of liquid contamination
  20. 20. John Crane Turbomachinery- Create a clean environment for the seal under all conditions
  21. 21. Clean seal gas injection– Normal operation EXTERNAL GAS Flow path of Filtered Process Gas FILTER MODULE seal gas under PROCESS normal dynamic GAS FI FI operating conditions Process Gas
  22. 22. No seal gas flow at settle out conditions Filter No differential pressure = no flow FI FI Seal contaminated Settle- out Conditions by process gas (Pressurised standstill) Can Lead to Seal hang up on start-up
  23. 23. Seal environment solutions from SEPro - Heated filtered seal gas on demand during shutdown and periods of low differential pressure ensure the seal is constantly maintained in optimum condition and readiness for re-start.  When the unit is statically pressurised there is no seal gas flow  JT expansion causes cooling  Any liquids or heavy ends are deposited inSEPro - Superior by design the seal• Application developed gas circulator  This results in serious contamination and• Inbuilt safety and monitoring features• Plug and play operating philosophy premature seal failure• Auto start / stop functions  The SEPro system provides flow to keep• Onboard logic and control the seals clean and dry  Provides major increase in seal life
  25. 25. Seal environment solutions from Experience has proven that process contamination is the biggest single contributor to premature gas seal failure Maintain optimum seal condition Increase compressor availability Prevent liquid contamination at seal faces Prevent process debris contamination Increase dry gas seal MTBF NACE material compatibility ATEX and PED optionsSEPro - More than just another filtered gas package
  26. 26. John Crane Turbomachinery Ensure the OB seal is adequately alarmed
  27. 27. Ensure the OB seal is adequately alarmedEXTERNAL Filtered N2 Secondary Gas N2 SECONDARY GAS FILTER MODULE PCV FILTER Filtered Process Gas MODULEPROCESS GAS  Ensure OB seal is alarmed FI FI FI FI • LP in PV = OB seal failure • HP in PV = IB seal failure Process + N2 Gas to Flare PI PI FO FO FI FI FLARE Process Gas
  28. 28. John Crane TurbomachineryEnsure adequate separation from bearing oil
  29. 29. Type 82 Barrier Seal - Function
  30. 30. Ensure adequate Barrier Seal SupplyEXTERNAL Filtered N2 Secondary Gas N2 SECONDARY GAS FILTER MODULE PCV FILTER Filtered Process Gas MODULE  Ensure Barrier gasPROCESS GAS supply pressure is PI FI FI FI FI PI adequately controlled • Should be controlled to 0.3 to 0.5 bar Barrier seal pressure controlled with PCV’s • Barrier Seal leakage Process + N2 with time changes •Gas to Flare Interlock with bearing oil PI PI FO FO FI FI FLARE VENT Process Gas N2 to Atmosphere
  31. 31. Improved Product - Type 83 Barrier Seal Type 82 Bushing Upgrade - the Type 83 Barrier SealWave SpringGarter Spring Carbon Segments
  32. 32. New Development - Type 83 Barrier SealType 83 Barrier Seal Dry Oil Gas side Seal side
  33. 33. Type 83 Barrier Seal
  34. 34. John Crane Turbomachinery Ensure The OEM’s test with job seal system
  35. 35. Ensure the compressor is tested withjob panel  The OEM’s often provide a temporary seal system for the compressor testing. • Complex systems are left untested • SD conditions left unchecked • Lead to ‘prototype’ trials on site  If there is a problem with the seal it is often not picked up • Catastrophic failureComplex Gas Seal control panel • Impossible to diagnose& booster for BP Horn Mountain
  36. 36. Specification for maximum reliability- Summary Use polymer seals in place of O rings • Even at low pressures XP seal show benefits Ensure the gas is clean and dry • Use coalescing filters to remove liquids • Ensure adequate draining • Heat trace lines + insulate • Use SEPro system to provide seal gas under shutdown • Protects the seal from process gas when the machine is shutdown • Use heaters to increase margin over liquid formation • Use a thermocouple within the seal to monitor temp
  37. 37. Specification for maximum reliability- Summary Ensure adequate OB seal failure sensing Confirm test conditions reflect duty • Axial movements • Transient movement Vacuum testing • Temperature transients • Confirm seal vendor test conditions reflect duty Leakage monitoring • Ensure flowmetres are correctly sized • Check shutdown flow rates Barrier seal gas system • Ensure adequate barrier seals are provided • Adequate pressure control (0.3 to 0.5 bar) • Confirm failure sensing • Provide bearing oil interlock • Consider explosive mixtures / including failure condition
  38. 38. John Crane Gas Seals Offer:- Experience • More experience than the other gas seal vendors put together Global service • Local experience and support • Local repair service • All to a guaranteed global standard Technology • Proven high performance products specially selected for specific requirements
  39. 39. John Crane – World leaders in Dry Gas Seal Technology