1

Encotech Steam Path Audits

Presentation

2

Overview

• What is a Steam Path Audit?

• Benefits

• Cost

• Chronology of a Steam Path Audit

• STPE Results

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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

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Where

• On site

• Via FAX

• Individual parts in contractor’s shop

• At the OEM’s facility

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Benefits of a SPA

• Provides detailed inspection of steam path

• Repair/replacement decisions, early in outage

• Aid decisions for future repair

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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

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Cost

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

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The Outage Time-Line

TURBINE OUTAGE

Shutdown Startup

Pre-Outage Test Opening SteamPath Audit

Closing SteamPath Audit

Upgrade andMaintenance

Post-OutageTest

Disassembly Reassembly

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Chronology

of a Steam

Path Audit

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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

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Coordinate Activities

• Coordinate activities with owner

– Review safety procedures

– Sign contract

– Plan around grit blasting schedule

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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

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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

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

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SPA - Flow Path Damage• Deposits

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Flow Path Damage• Foreign object damage (FOD)

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Surface Roughness

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Before Lifting Rotor

• Chart rotor for actual radial clearances

– Interstage packings

– Shaft end packings

– Root spill strip clearances

– Tip spill strip clearances

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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

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Rotor

• Inspect rotating blades

– Surface finish

– Solid particle erosion

– Mechanical damage

– Cover deposits

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Geometric Data

• Geometric data for the steam path must be obtained to properly model turbine

– Blade heights and widths

– Blade root diameters

– Balance holes

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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

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Completion

• Enter audit data into STPE™ computer model

• Review results

• Present preliminary report to owner at site

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STPE

Steam Turbine Performance Evaluation

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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

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Opening Audit Power Loss

0

200

400

600

800

1000

1200

1400

1600

1800

Inte

rsta

ge

Pa

ckin

gs

En

d P

ack

ing

s

Tip

Sp

ill S

trip

s

Mis

cella

ne

ou

sL

ea

kag

es

Flo

w P

ath

Da

ma

ge

Su

rfa

ceR

ou

gh

ne

ss

Co

ver

De

po

sits

Tra

ilin

g E

dg

eT

hic

kne

ss

Po

we

r L

os

s (

kW

)

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Closing Power Loss

-200

200

600

1000

1400

1800

2200

2600

3000

Inte

rsta

ge

Packi

ngs

End P

acki

ngs

Tip

Spill S

trip

s

Mis

cella

neous

Leaka

ges

Flo

w P

ath

Dam

age

Surf

ace

Roughness

Cover

Deposits

Tra

iling E

dge

Thic

kness

Recovery

Po

we

r L

os

s (

kW

)

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Results by CategoryEncotech STPE - Fossil 5.2....05/11/2000..................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 152.9 118.20 1.10

End Packings 282.4 220.37 2.05

Tip Spill Strips 329.3 257.87 2.40

Miscellaneous Leakages 8.7 6.62 0.06

Flow Path Damage Results 109.5 20.42 0.19

Surface Roughness 122.7 94.70 0.88

Cover Deposits 0.0 0.00 0.00

Trailing Edge Thickness 0.0 0.00 0.00

Hand Calculations 0.0 0.00 0.00

--------------------------- ---------- --------- ---------

Totals 1005 759.8 7.07

See Casing Totals For Flow Change Impact

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Results by Stage

Interstage Packing Root Spill Strip

<---Clearance----> <--Clearance---> Change In

Location Design Measured Design Measured Power Loss Heat Rate

Descr. (IN.) (IN.) (IN.) (IN.) (KW) (BTU/KWH)

-------- ------ -------- ------ -------- ----------- ---------

Stage 2 0.010 0.075 0.000 0.000 56.7 43.52

Stage 3 0.010 0.024 0.000 0.000 14.9 11.42

Stage 4 0.010 0.019 0.000 0.000 16.6 12.71

Stage 5 0.010 0.014 0.000 0.000 8.8 6.76

Stage 6 0.010 0.021 0.000 0.000 17.4 13.29

Stage 7 0.010 0.010 0.000 0.000 3.4 2.57

Stage 8 0.010 0.014 0.000 0.000 8.4 6.43

Total Power Loss (KW)........................ 153

Total Change In Heat Rate (BTU/KWH).......... 118.2

Total Heat Rate Loss (%)..................... 1.1

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