| Title | Wayang Windu Power Station Turbine Rotor Repair Review |
|---|---|
| Authors | Alan C. Robinson, Scott G. Baigent & H. Brett Houston |
| Year | 2013 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Geothermal, Turbine, Rotor, Repair, Star Energy, ProGen |
| Abstract | This paper reports the findings of a review of the repair options for the rotor removed in 2012 from the Star Energy Wayang Windu Geothermal Power Station 110MW Unit 1 Turbine. The rotor was replaced as a result of an assessment by the Fuji, – the Original Equipment Manufacturer (OEM), of the erosion damage found in the 2009 overhaul. A new rotor was installed and the original rotor was set aside as an emergency spare. ProGen Ltd. conducted an independent technical review1 of the spare turbine rotor in March 2013 to assess the current condition of the rotor, confirm those findings of the previous inspections2,3, highlight any further issues, explore possible repair options and undertake an economic analysis of those viable repair options. Each side of the central body of the rotor (stages 1-5 and stages 6-10) was found to have severe damage to the interstage sealing zones which could impact on the axial support for the rotating blades. It was concluded that the rotor could be refurbished to provide a fully serviceable spare for the remaining operational units. Several repair methods including submerged arc welding, laser cladding and a machined bush ring were investigated for the restoration of the rotor. The results of the discounted cash flow (DCF) analysis showed that all three of the viable repair options provide a more economical solution when compared to a new replacement rotor. In addition, the analysis showed the benefit of applying high velocity oxyfuel (HVOF) coating spray at each overhaul. The next stage of the repair options review is to develop and issue a request for tender (RFT) document to service workshop providers. This will allow further exploration of the feasibility and costs of the various options and also open the market for further potential options. |