KWG12 ROTOR 1ST STAGE REPAIR: STATIC BALANCING, SIMULATION AND RE-BLADING

Olkaria Wellheads has grappled with premature fracture of 1st stage blades on C50 geothermal steam turbines. On December, 29th 2018, KWG12 failed to progress beyond critical speed owing to high turbine vibrations after the turbine suffered two fractured 1st stage blades. The rotor needed re-blading and balancing. It was considered cost-effective to do in-house repairs using 1st stage blades recovered from a grounded C50 rotor. Repairs entailed static balancing of all 1st stage blade masses, simulation and re-blading. Success was epitomized by timely availing of the plant after 15 days outage, at 5000kW rated capacity and normal vibrations of 30µm. The initiative has kept the plant operational as new blades are procured, besides cushioning the plant from incurring downtime losses arising from long procurement lead time. Whereas the 15 days repairs incurred KShs. 16.9 million in direct and indirect costs, the plant accrues over KShs. 17.4 million monthly in revenue.