Efficient Shaft Sealing Solutions for Small Steam Turbines

1. Bearing Housing/Pedestal Bearing Steam Leakage In Small Steam Turbines Turbine Case Oil Carbon Seals

2. Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals

3. Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals 230 degrees f. 230 degrees f. Temperature

4. Bearing Housing/Pedestal Bearing Steam Turbine Case Oil Carbon Seals 230 degrees f. 230 degrees f. Temperature

5. Condensate Magnet Bearing Housing/Pedestal Bearing Seal Failure Steam Turbine Case Oil Carbon Seals 230 degrees f. 230 degrees f. Temperature

6. Bearing Housing/Pedestal Bearing Steam Path Turbine Case Oil Carbon Seals Steam moves out of the case, down the shaft and past the carbon seals to atmosphere.

7. Condensate Magnet Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals 230 degrees f. 230 degrees f. Temperature

8. Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals Some steam dissipates into the atmosphere. In some instances (such as in cold climates), this could cause a visibility hazard.

9. Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals It could also cause a slipping hazard as condensate collects on the ground, or can cause severe burns if contacted near the exhaust path.

10. $$$$$$$$$$ Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals $$$$$$$$$$ Lost steam is also money thrown into the wind.

11. Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals Yet another consideration – if water enters your bearing housing, the integrity of your oil (lubrication system) will be compromised.

12. Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals This could lead to bearing failure and ultimately, equipment failure.

13. Condensate Magnet Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals When shaft seals fail, your only barrier against oil contamination are your bearing case seals.

14. Condensate Magnet Bearing Housing/Pedestal Bearing Turbine Case Oil Carbon Seals These seals can be standard OEM “H” seals, or “upgrades” such as modified “H” seals (Disrupter Seals) or aftermarket Barrier Seals.

15. Solutions #1 Try to reduce or eliminate steam leakage at the source.

16. Solutions #2 Protect your oil from contamination.

17. Carbon Seals The standard shaft seals on most small steam turbines are carbon rings.

18. Carbon Seals If installed correctly, they provide a good seal. However they do deteriorate rapidly.

19. Effective Clearance Over Time

20. Carbon Rings Advantages • Inexpensive • Easy to install • Perform well when properly sized and installed • Lightweight Disadvantages • Easily cracked/ chipped • If not properly sized, can either seize on shaft or leak too much • Short life, resulting in high leakage after short time

21. Mechanical Seals

22. Mechanical Seals Advantages • Best sealing performance • Longer life than standard carbon seals Disadvantages • Expensive initial investment • Difficult to install, requires entire rotor to be removed for installation/ maintenance • Can require permanent case modifications • Finite life-span before a costly overhaul is required.

23. Brush Seals

24. Brush Seals Advantages • Moderately priced • More durable than carbon seals • Extremely long life Disadvantages • Must be installed in shop • Not stocked for all size turbines • Relatively new technology for steam applications • Heavy “floating” seals can gravitate downward on turbines that cycle, thus decreasing efficiency

25. Brush Seals Current Applications • Utility Turbines • Mechanical Drive Turbines • Gas Turbines – Aircraft & Industrial • Single Stage Turbines • Elliott – All YR sizes • Dresser Rand • General Electric • Westinghouse

26. Rotation Shaft Brush Seals Brush Pack

27. Holder Holder is SS Fence Flow Brush Pack Brushes are a Haynes 25 material

28. Brush Seals • Little or no case modifications beyond original design specifications. • Lower sustained leakage than carbon rings. • Indefinite life span eliminating periodic replacement.

29. Brush Seals Installation Considerations

30. Sealing faces and ID of carbon box are machined to assure a good seal fit. Compressor & Turbine Services. LLC

31. Internal Alignment is Important On Fixed (non-floating) Brush Seals Compressor & Turbine Services. LLC

32. Suggested Shaft Coatings – None – Base Metal Chromium Carbide Tungsten Carbide (preferred) Compressor & Turbine Services. LLC

33. Leakage Data Compressor & Turbine Services. LLC

34. Leakage Data From SST Test • Test comparing brush seals with cold (new) carbon seals • Brush seals installed with “zero” clearance • Carbon seals installed with 2.5 mil radial clearance • Carbon seals exhibit equivalent clearance of 4.3 mils B = Brush Seal C = Carbon Seal

35. Brush Seals vs. Carbon Rings Effective Clearance over Time Compressor & Turbine Services. LLC

36. Effective Clearance over Time Carbon seals will degrade almost immediately. Brush seal performance will always stay the same. Compressor & Turbine Services. LLC

37. Brush Seals Two Approaches * Stand Alone Application * Brush/Carbon Combo Compressor & Turbine Services. LLC

38. Brush Seals for Steam Turbines May be used as a replacement for Carbon Rings Or May be used in conjunction with Carbon Rings

39. Brush Seals Stand-Alone Application Compressor & Turbine Services. LLC

40. Application: Brush Seals to Replace Carbon Rings Non Floating Seals COST: Around $10k Per SST Compressor & Turbine Services. LLC

41. Application: Brush Seals to Replace Carbon Rings More Risky Than Brush/Carbon Combination Since Brush Seals DO NOT Have a History for this Application. Only recommended for turbines that are in continuous service. (floating seals) Compressor & Turbine Services. LLC

42. Application Requirements:Brush Seals as Replacement for carbon rings Drain • Minimum radial space between shaft and packing box ID of 1.0 inch typically • Maximum pressure drop across one seal is 150 psid • Packing box must be reasonably aligned with bearings • Best used on turbines that are in continuous operation Brush Seals

43. Split line Brushes Anti-rotation pin Sealing face Application: Brush Seals to Replace Carbon Rings Non Floating Seals Compressor & Turbine Services. LLC

44. Elliott BYRHH Compressor & Turbine Services. LLC

45. Flow No.1 Drain Pipe No.2 No.3 Compressor & Turbine Services. LLC

46. Brush Seals - Used With Carbon Rings Compressor & Turbine Services. LLC

47. A More Conservative Approach Estimated around 100 turbines in operation with Brush Seals in this configuration. Compressor & Turbine Services. LLC

48. Brush Seals/Carbon Rings - A Winning Combination • No case modifications beyond original design specifications. • Lower sustained leakage than stand-alone carbon rings. • Indefinite life span eliminating periodic replacement. • Protects carbon rings from contamination • Reduces pressure on carbon rings Compressor & Turbine Services. LLC

49. Leakage Data From SST Test • Test comparing brush seals with cold (new) carbon seals • Brush seals installed with “zero” clearance • Brush seals exhibit equivalent clearance of 3.4 mils radial • Carbon seals installed with 2.5 mil radial clearance • Carbon seals exhibit equivalent clearance of 4.3 mils B = Brush Seal C = Carbon Seal

50. COST: Around $ 3k – 6k Solid Ring Design Compressor & Turbine Services. LLC