CALPINE

Fuel Variability and Dry Low NOx Gas Turbines

Maritimes & Northeast Pipeline Technical ConferenceJuly 15th, 2008

Peter SoCalpine Turbine Maintenance Group

Calpine Corporation 1

CALPINE

7/16/2008

Peter So’s Background

BS of Mechanical EngineeringState of California Professional Engineer, Mechanical Engineering14 years of industry experienceEx-GE Field Engineer, startup engineer, Dry Low NOx tunerInvolved with early DLN 2.0 / DLN 2.6 startup activitiesManage a group responsible for controls and tuning support of Calpine’s GE 7FA fleet, total group experience just short of 50 yearsSteering committee member of GE 7F Users Group and past co-chairperson

Calpine Corporation 2

CALPINE

7/16/2008

Topics for Discussion

Calpine OverviewDLN Compare to Conventional NOxDLN Systems – Key IssuesDLN Systems – Combustion Tuning BasicsGE DLN System at WestbrookCalpine’s ExperienceGE Wide Wobbe System – Many Unanswered QuestionsSummaryList of Issues

Calpine Corporation 3

CALPINE

7/16/2008

Calpine Overview

Calpine is the largest natural gas consumer in the United States and has substantial experience with operating F/G DLN technology gas turbines

82 power plants - 24,000 MWs

91 F/G technology gas turbines with DLN combustion systems:47 GE 7FAs – 1,319,772 operating hours40 Siemens 501Fs – 1,543,789 operating hours4 Siemens 501Gs – 103,289 operating hours

Calpine Corporation 4

CALPINE

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Calpine Overview – TMG

Calpine Turbine Maintenance Group formed in 1992

Self perform Combustion Inspections, Hot Gas Path, Majors amongst other maintenance activities

Staff of close to 60 and growing

Self perform combustion tuning activities since early 2000

Calpine Corporation 5

CALPINE

7/16/2008

DLN Compare to Conventional NOx

Dry Low NOx - lower exhaust NOx levels (as low as 5 ppm vs25 ppm)Benefits of DLN:

Lower emissionsLess maintenance effect on combustion and hot gas path partsLower operating cost of water/steam

Challenges of DLN:System more sensitive to variables (i.e. fuel quality, ambient temperature)Narrower operating range due to emissions limitationsSystem more complex, experienced O&M staff required -Troubleshooting is difficult

Calpine Corporation 6

CALPINE

7/16/2008

DLN Systems – Key Issues

Importance of Fuel Specifications:Gas turbine design based on historical fuel qualityOEM specifies limits to range of operationOutside of these specifications - reduced reliability and parts damage

Wobbe Index (WI) rangeOne of several interrelated gas quality parametersEven within OEM range - limited adjustability to changesOutside of historical fuel range – fuel impacts unknown and may require equipment changesOutside of OEM/historical range – additional cost, downtime WILL occur

Rate of change:As important as WI rangeHistorically not much variation in gas quality - rate of change has not been a concernGas turbines designed in anticipation of a limited rate of changeSiemens – has always specified rate of change criteriaGE – not initially, but does now with Wide Wobbe OpFlex system

Calpine Corporation 7

CALPINE

7/16/2008

DLN Systems – Combustion Tuning Basics

Four criteria:Combustion dynamicsEmissions – permit requirementsLean blow out – stability concernsPerformance – Depending on circumstance –need to optimize for MWs, BTUs and/or turndown

Tuning for fuel quality:Need to experience actual gas quality to properly tuneTuning in anticipation of gas is “hit or miss”

Calpine Corporation 8

CALPINE

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GE DLN System at Westbrook

Westbrook Energy Center – 537 MW power plant located just outside of Portland, MEInterconnected with M&N @ Joint Facilities2 GE 7FA+e Gas Turbines with DLN 2.6 system -designed for 9 ppm NOxStack NOx permit with SCR is 2.5 ppmDLN 2.6 fuel system includes 5 control valves, 14 combustion cans, 64 individual fuel nozzles, hundreds of individual injection points

Calpine Corporation 9

CALPINE

7/16/2008

GE DLN System at Westbrook (cont.)

Diagrams/Pictures Courtesy of GE - GER-3568G

Calpine Corporation 10

CALPINE

7/16/2008

GE DLN System at Westbrook (cont.)

Diagrams/Pictures Courtesy of GE - GER-3568G

Calpine Corporation 11

CALPINE

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GE DLN System at Westbrook (cont.)

DLN 2.6 System is highly sensitiveGreat precision and fine tuning required at all timesDetermining the exact adjustment needed takes substantial amounts of time and requires information on multiple variables (i.e. fuel quality, ambient temperature)Typical tune adjusts schedule by 0.5-3% which equates to 0.005 to 0.034 inches change in actual PM3 valve movement as an example

Calpine Corporation 12

CALPINE

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GE DLN System at Westbrook (cont.)

Tuning at Westbrook and most Calpine sitesRemote tuning capable with onsite personnel -provides quicker reaction to combustion issues

Continuous Dynamics Monitoring System (CDMS) – monitors and records combustion dynamicsIn-house tuning expertiseComputer infrastructureReflects a substantial capital investment at Westbrook and across Calpine

Calpine Corporation 13

CALPINE

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Calpine’s Experience

Small changes in WI can have substantial adverse impact on combustion dynamics:Recent Experience

WI variation of +/- 1.3%Combustion dynamic amplitudes increased 167% to 260%Resulted in undesirable combustion conditions

Calpine Corporation 14

CALPINE

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Calpine’s Experience (cont.)

6-11-2008

0

0.5

1

1.5

2

2.5

3

3.5

1330 1335 1340 1345 1350 1355 1360 1365 1370 1375

Wobbe Index

Dyn

amic

s (p

si)

GT1 Dynamics GT2 Dynamics

Calpine Corporation 15

CALPINE

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Calpine’s Experience (cont.)

Lean blow out events at Westbrook

12/1/2007, 12/2/2007, 12/5/2007Unexpected gas supplier changeBTU levels were lower than historical

Calpine Corporation 16

CALPINE

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Calpine’s Experience (cont.)

Use of third party componentsHistory of hardware issues with OEM partsNon-OEM parts meet or exceed OEM specificationsUse of non-OEM parts resolves hardware issues and enhances turbine performanceMultiple supplier options - enhances parts availability

Calpine Corporation 17

CALPINE

7/16/2008

GE Wide Wobbe System – Many Unanswered Questions

GE Simulation and Field test is insufficient proof of system performance:

Simulation Testing – not real world experienceField Testing – changing GE’s Modified Wobbe Index by fuel temperature does not reflect true WI change

Not much history – only 12 units with system. Fleet leader has less than 8000 operating hours and has experienced a WI range of only +/- 1.7% to dateEven with Wide Wobbe OpFlex, GE does not guarantee unit stability/operation outside of its current fuel specification and imposes a +/- 4% per minute rate of change

Calpine Corporation 18

CALPINE

7/16/2008

GE Wide Wobbe System (cont.)

GE “reluctant” to guarantee system operability with third-party design componentsGE proprietary software reduces operator’s troubleshooting capabilityEach model system has to be individually tuned at each hardware maintenance cycle7 Lean Blow Out Events of Wide Wobbe OpFlexcontrol system on February 14, 2008

Calpine Corporation 19

CALPINE

7/16/2008

Summary

GE’s DLN system is very sensitiveGE’s Wide Wobbe system is still in development and not a proven solution to fuel variabilityLimiting fuel quality variations to match OEM specification is critical to reliable turbine operationsWobbe Index range is just one parameter of gas qualityWI rate of change is an equally important parameter

Calpine Corporation 20

CALPINE

7/16/2008

List of Issues

WI range needs to be set consistent with OEM specificationsA WI rate of change is required consistent with OEM specificationsAn adequate gas quality posting system needs to be developed that addresses generator needs with respect to data quality, timing and longevity