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Details of a Steam Path Audit

Details of a Steam Path Audit. Paul Roediger Encotech, Inc. Overview of Presentation:. Audit Overview Benefits Chronology Measurements Calculations Results / Report Conclusion. Audit Overview :. Inspection of the steam path (Comparison to new & clean conditions)

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Details of a Steam Path Audit

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  1. Details of aSteam Path Audit Paul Roediger Encotech, Inc.

  2. Overview of Presentation: • Audit Overview • Benefits • Chronology • Measurements • Calculations • Results / Report • Conclusion

  3. Audit Overview : • Inspection of the steam path (Comparison to new & clean conditions) • Results: clear priority for maintenance decisions • Benefit: maintenance dollars used with the highest return • Verification of maintenance

  4. Overview: What: Inspection of the steam path (determined by VWO heat balance conditions) When: Immediately after steam path is exposed and again after maintenance has been performed

  5. Benefits OPENING AUDIT • Identification of degradation • Cost-effective maintenance actions CLOSING AUDIT • Quality check on maintenance performed during the outage • Performance improvement resulting from individual maintenance actions • Expected return-to-service performance

  6. Required Resources • Computer • Loss Calculation Software • One or Two Auditors • Measurement Tools • Radial Packing Gauge • 6” Digital Caliper • Tape measure • Ball Gauges • Surface Roughness Comparator

  7. Maintenance Action Itemsfor B/C > 3.5

  8. Maintenance Action Itemsfor B/C < 3.5

  9. Chronology • Model • On Site • Analysis / Report

  10. Model Create model using the Thermal Kit • Design heat balance (VWO) • Turbine cross section • Clearance and steam seal diagram • First stage shell pressure curve

  11. SPA On-Site Time-Line Disassembly Reassembly

  12. Measurements • Geometry • Clearances • Surface roughness • Damage • Solid Particle Erosion • Throat Openings • Steam Path Length

  13. Clearance Measurements

  14. What Tooth Throttles Steam?

  15. Slant Tooth Packing

  16. Honeycomb Packing

  17. Mechanical Damage

  18. Solid Particle Erosion

  19. Throat Opening Measurements

  20. Ball Gauge Measurement

  21. Surface Roughness Measurement

  22. Miscellaneous Leakage Measurements

  23. Cover Deposits

  24. Nozzle Repair

  25. On Site - Day 1 After Top is Lifted • Inspect horizontal joint • Measure Stationary Blade Geometry • Measure top half tooth heights • Measure packing clearances • Inspect shell sealing surfaces

  26. On Site - Day 2 Rotor Removed • Measure solid particle erosion damage • Measure deposit thickness • Measure stationary and rotating blading surface roughness • Inspect for mechanical damage

  27. On Site - Day 3 • Measure bottom half tooth heights • Measure trailing edge thickness • Measure turbine geometry • Inspect snout rings

  28. Analysis / Preliminary Report • Input data & analysis • Print Steam Path Audit reports • Give preliminary presentation on site

  29. Calculations • Martin’s Formula • General Flow Equation • Dollar Value of Heat Rate • Annual Fuel Cost Savings • Cost of Lost Capacity

  30. Martin’s Formula Calculation

  31. General Flow Equation W = Flow (lb/h) K = Packing type constant C = Rubbed coefficient A = Area (sq in.) P1 = Upstream Pressure (psia) v1 = Upstream specific volume (ft 3/lb) P2 = Downstream Pressure (psia) k = Isentropic exponent (1.3 typical) 2406.5 = Unit conversion constant

  32. Common Tooth Types

  33. Tip spill Strip Clearance Ken Cotton Chart – Reference Table [449] kW loss per mil excess clearance per stage: 7+ ((591.9 – 500) / (500 – 100)) x (7.0 -2.5) = 8.03 kW/mil

  34. Dollar Value of Heat Rate Degradation (Based on G.T.H.R.) FC = Cost of fuel $/million BTU’s GR = Rating of turbine in KW CF = Turbine capacity factor in % 8760 = Hours in a Year BE = Boiler Efficiency = $8,012.20 / year

  35. Annual Fuel Savings - $ Year R - Rating of turbine in KW CF - Turbine capacity factor in % F - Cost of fuel $/million BTU’s HR - Change in heat rate in % SHR - Station heat rate BTU’s/KW HR Example: = $650,430/year

  36. Cost of Lost Capacity Where: L = lost revenue $/year K = percentage of year at max. capacity (%) M = average wholesale price of power ($/(MWh)) R = unit capacity (kW) D = degradation in performance (%) For: K = 50% M = 45 $/(MWh) R = 600,000 kW D = 1% L = 1,182,600 $/year

  37. Results OPENING AUDIT • Quantification of losses measured in pre-outage test • Listed cost-effective maintenance actions CLOSING AUDIT • Quality check on maintenance performed during the outage • Performance improvement resulting from individual maintenance actions • Expected return-to-service performance

  38. Opening Audit LossHeat Rate Loss by Category

  39. Opening Audit LossHeat Rate Loss by Casing

  40. Opening Audit: Summary

  41. HP Casing - Loss Summary

  42. HP Casing – Tip Spill StripsOpening Audit

  43. HP Casing – Tip Spill StripsClosing Audit

  44. Tip Spill Strips - Opening Audit

  45. Tip Spill Strips - Opening Audit

  46. Tip Spill Strips - Closing Audit

  47. Tip Spill Strips - Opening Audit

  48. HP - Repair or Replacement Cost

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