The Public Service Commission of Wisconsin on Aug. 22 approved Wisconsin Power and Light (WP&L) for a $19.5m inspection and refurbishment project at the gas-fired Riverside power plant that the utility acquired at the beginning of this year from Calpine (NYSE: CPN).
WP&L plans to undertake a hot gas path inspection and associated refurbishment at Riverside Energy Center Units 1 and 2, located in the town of Beloit, Rock County, Wisc.
Riverside consists of two combustion turbines, two heat recovery steam generators and one steam turbine, with a total generating capacity of approximately 600 MW combined cycle. Riverside was placed in service and became operational in June 2004. Rock River Energy LLC, an affiliate of Calpine, owned and operated the energy center until December 2012.
In April 2012, the commission approved the purchase of Riverside by WP&L. In the process of performing the due diligence for the purchase, WP&L and its consultant, Stanley Consultants, identified the need to conduct the hot gas path inspection in compliance with the turbine original equipment manufacturer, General Electric.
Since its initial operation in 2004, each unit has had one hot gas path inspection and there is a need for a second inspection at this time, the PSC noted. The timing of these inspections is generally planned based on the unit’s operating pattern of either hours of operation or number of starts, which is generally 24,000 hours or 900 starts. The last hot gas path inspection performed on Unit 1 was in April 2008 and on Unit 2 in May 2007. By November 2013, Unit 2 is expected to have experienced 1,109 accumulated starts since its last inspection and, by June 2014, Unit 1 will have experienced about 1,040 starts. Using the starts-based inspection cycle recommendations, the proposed maintenance is needed to minimize the risk to the units from thermal and mechanical fatigue.
WP&L is proposing to complete this task in three stages and plans to perform scheduled outages in the fall of 2013 and spring of 2014 to minimize operational impact.
- Unit 2 Outage, Fall 2013: A new set of combustion and hot gas parts and hardware will be purchased, and Unit 2 will be removed from service for three weeks in the fall of 2013. With the new hardware installed in Unit 2, the next hot gas path inspection would not be performed until the unit reaches the recommended 900 starts. In addition to the accumulated 900 starts, other factors like stresses to the hardware will be taken into account. The removed parts from Unit 2 will be refurbished and restored to minimum acceptance standards. The refurbishment process restores the parts to a condition allowing for another combustion cycle of 24,000 hours or 900 starts.
- Unit 1 Outage, Spring 2014: The refurbished parts from Unit 2 will then be installed in Unit 1 during the scheduled inspection in the spring of 2014. The parts removed from Unit 1 during its outage will also be refurbished and placed in inventory for future use.