Damodar Valley Corporation, Chandrapura Unit 2 Thermal Power Station Residual Life Assessment Summary report

摘要

The BHEL/NTPC/PFC/TVA teams assembled at the DVC's Chadrapura station on July 19, 1994, to assess the remaining life of Unit 2. The workscope was expanded to include major plant systems that impact the unit's ability to sustain generation at 140 MW (Units 1-3 have operated at average rating of about 90 MW). Assessment was completed Aug. 19, 1994. Boiler pressure parts are in excellent condition except for damage to primary superheater header/stub tubes and economizer inlet header stub tubes. The turbine steam path is in good condition except for damage to LP blading; the spar rotor steam path is in better condition and is recommended for Unit 2. Nozzle box struts are severely cracked from the flame outs; the cracks should not be repaired. HP/IP rotor has surface cracks at several places along the steam seal areas; these cracks are shallow and should be machined out. Detailed component damage assessments for above damaged components have been done. The turbine auxiliary systems have been evaluated; cooling tower fouling/blockage is the root cause for the high turbine back pressure. The fuel processing system is one of the primary root causes for limiting unit capacity. The main steam and hot reheat piping systems were conservatively designed and have at least 30 years left;deficiencies needing resolution include restoration of insulation, replacement of 6 deformed hanger clamp/bolts, and adjustment of a few hanger settings. The cold reheat piping system is generally in good condition; some areas should be re-insulated and the rigid support clamps/bolts should be examined. The turbine extraction piping system supports all appeared to be functioning normally.