Operations & Management – Business – Osprey Energy Center

Active performance monitoring of HRSGs

Osprey Energy Center
Calpine Corp 

Challenge. As plants age, small performance losses can be missed or accepted.

Solution. Through routine monitoring and spot checks of HRSG and steam-piping condition, users can locate issues and “nip them in the bud.” On a routine basis plant personnel review thermal and ultrasonic data to stay abreast of performance-related issues and remediate at the most opportune times.

   Thermal imaging of the HRSG on a panel-by-panel basis helps locate hot spots or increases in temperature profiles (Fig 2). This, combined with a periodic individual check of HRSG upper and lower penetration seals, allows for early identification of insulation losses and/or seal clamping effectiveness.

   Adjustments of penetration seals can reduce the likelihood of early failures and decrease operating costs. Site personnel have been trained in adjusting penetration seals by the OEM and installer, increasing the level of ownership and participation.

   Select areas of boiler feedwater piping have had inspection ports added to allow ultrasonic testing (UT) of wall thickness to monitor for FAC (Fig 3). During outages, HRSG tube bends are surveyed. Early FAC detection is key for piping replacements to be scheduled and planned in an effective manner or, ideally, prevented altogether. Thickness testing is one of the ASME B31.1 Chapter VII recommendations for condition assessment of covered piping systems.

   Resistance temperature detectors (RTDs) were installed on the downstream side of HRSG drain-valve outlet piping to monitor valve seating effectiveness (Fig 4). Questionable valve leaks by can be verified using ultrasonic emission testing. This monitoring program of the drain valves allows for early detection and improved pre-outage planning.

Results. By keeping tight control of heat within the system, the facility keeps its heat rate low and marketability high. By way of comparison, 2011 heat rate bested the 2005 heat rate with a lower forced-outage rate.