1 Encotech Steam Path Audits Presentation

2 Overview What is a Steam Path Audit? Benefits Cost Chronology of a Steam Path Audit STPE Results

3 What is a Steam Path Audit? A detailed inspection of the stationary and rotating steam path components An accounting of performance losses on a stage- by-stage basis A presentation of losses in power and heat rate

4 Who Owner’s Personnel OEM Contractor Encotech

5 Where On site Via FAX Individual parts in contractor’s shop At the OEM’s facility

6 Benefits of a SPA Provides detailed inspection of steam path Repair/replacement decisions, early in outage Aid decisions for future repair

7 Benefits of a SPA (Con’t) Audit quality of repair work prior to re- installation Isolate expected performance on new parts Provides excellent record/history of equipment condition for future reference

8 Cost Dependent on Location OEM Capacity (MW) No. of Casings No. of Stages

9 The Outage Time-Line DisassemblyReassembly

10 Chronology of a Steam Path Audit

11 Computer Model Create turbine model at Encotech’s office using the Thermal Kit –Design heat balance (VWO) –Turbine cross section –Clearance and steam seal system diagram –First stage shell pressure curve

12 Coordinate Activities Coordinate activities with owner –Review safety procedures –Sign contract –Plan around grit blasting schedule

13 Coordinate Activities Coordinate with outage crew –Place upper half of casing w/ horizontal joint up or lay on ground w/ trailing edges up –Leave all packing (interstage & shaft end) in place until measured. This speeds SPA process significantly –All stages must be inspected prior to grit blasting

14 Sequence of Events (Casing Lifted) Inspect casing horizontal joint for leakage paths Measure blade geometry Measure packing teeth, interstage, tip, root, and & shaft end Create a photographic record of the steam path

15 SPA - Flow Path Damage Solid particle erosion (SPE)

16 SPA - Flow Path Damage Deposits

17 Flow Path Damage Foreign object damage (FOD)

18 Surface Roughness

19 Before Lifting Rotor Chart rotor for actual radial clearances –Interstage packings –Shaft end packings –Root spill strip clearances –Tip spill strip clearances

20 After Lifting Rotor Measure lower half tooth heights –Interstage packing and shaft end packing –Root and tip spill strips Inspect lower half diaphragms –Surface roughness –Solid particle erosion –Mechanical damage

21 Rotor Inspect rotating blades –Surface finish –Solid particle erosion –Mechanical damage –Cover deposits

22 Geometric Data Geometric data for the steam path must be obtained to properly model turbine –Blade heights and widths –Blade root diameters –Balance holes

23 Photographic Record Photographs of the steam path document condition –All packing teeth –Trailing edges of stationary and rotating blading –Specific damage associated with the steam path

24 Completion Enter audit data into STPE™ computer model Review results Present preliminary report to owner at site

25 STPE Steam Turbine Performance Evaluation

26 Results Quantification of losses measured in pre-outage test Quality check on maintenance performed during the outage Performance improvement resulting from individual maintenance actions Expected return-to-service performance

27 Opening Audit Power Loss

28 Closing Power Loss

29 Results by Category Encotech STPE - Fossil /11/ Turbine Audit Summary County Unit 1 Turbine Totals Open audit 05/08/2000 Change In Heat Rate Power Loss Heat Rate Loss Audit Section (KW) (BTU/KWH) (%) Interstage Packings End Packings Tip Spill Strips Miscellaneous Leakages Flow Path Damage Results Surface Roughness Cover Deposits Trailing Edge Thickness Hand Calculations Totals See Casing Totals For Flow Change Impact

30 Results by Stage Interstage Packing Root Spill Strip Change In Location Design Measured Design Measured Power Loss Heat Rate Descr. (IN.) (IN.) (IN.) (IN.) (KW) (BTU/KWH) Stage Stage Stage Stage Stage Stage Stage Total Power Loss (KW) Total Change In Heat Rate (BTU/KWH) Total Heat Rate Loss (%)

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