EtaPRO™ Performance & Condition Monitoring
Combined Cycle Power Plant Case Study
The case studies described below are based on actual events.
Malfunctioning Gas Turbine Combustor
At the Stony Brook Energy Center, EtaPRO’s Gas Turbine Can-Alyzer resulted in increased availability during a return from a maintenance outage. On start-up, a cold combustor on a GE Frame 7 gas turbine was detected by EtaPRO and the unit was shut down for inspection. Maintenance personnel went immediately to the combustor suspected by the Can-Alyzer and found a problem in the fuel supply line. Having advance knowledge of the location of the problem combustor allowed the unit to be returned to service in one-third the time, thereby improving availability.
Failed Fuel Gas Meter
At the Siemens V84.2-based Flynn Power Plant, EtaPRO was deployed for overall plant heat rate and capacity acceptance testing. In the days preceding the acceptance tests, the input/output plant heat rate was observed to be 8% higher than design, which had the potential to delay commercial operation. The EtaPRO system was used to diagnose inaccurate fuel gas metering as the cause of the high indicated heat rate. While the meter’s self-diagnosis indicated normal operation, an internal inspection revealed improper installation, the meter was repaired and all tests completed per the original schedule.
Increasing Performance Awareness at the Operating Level
At Conectiv’s Hay Road Power Complex, EtaPRO provides key heat rate and capacity indicators to the distributed control system (DCS), where they are alarmed for operator action. The plant operators are aware of items within their control that have a dramatic impact on heat rate and capacity. For example, through an energy balance on the heat recovery steam generator (HRSG), EtaPRO alerts the operator when the bypass damper is out of position or leaking excessively. Bypassing the HRSG with only 5% of the gas turbine exhaust decreases efficiency of a typical combined cycle power plant by as much as 1%.
Optimizing Gas Turbine Wash Frequency
Maintaining maximum gas turbine capacity requires routine on-line and off-line water washes to restore capacity lost due to compressor fouling. Many plants schedule washes at a set frequency, rather than applying economic principles to maximize profitability. EtaPRO’s Gas Turbine Wash Advisor uses the observed rate of degradation to predict base load capacity and compares it to the expected load forecast. The time in the future at which the gross profit per period hour is a maximum determines the optimum wash date and time. If a wash is scheduled too early or too late, the gross profit per period hour declines. For example, washing a day early on a 170 MW based loaded engine results in a decrease in gross profit of $2,000 per wash cycle or $50,000 annually.
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