COAL MILL PINION MAIN REDUCER GEARBOX BEARING DAMAGE DETECTION USING CO- ORDINATED CONDITION MONITORING AT DTPS

摘要

This paper shares a success story out of the Implementation of co-ordinated Condition Monitoring techniques at DTPS, wherein imminent Pinion & Main Reducer Gearbox bearings damage of HT auxiliary Coal Mill - 1CD was diagnosed. On 08.12.2011 Offline Pinion DE & NDE axial vibration reading deviated from 5.5 to 6.0 and 8.5 to 9.5 mm/sec (RMS) respectively At same time Online vibration of Pinion NDE axial started fluctuating to alarm level i.e. 11.2 mm/sec and alarm appeared in SOE of PCR - 01 Similarly Acceleration value of Main Reducer Input & Intermediate bearing deviated from 2.5 to 3.5g and 2.0 to 2.4g (Peak) respectively Also Noise level increased from 98.3 to 99.8 dB and Ultrasonic monitoring level from 7 to 9 LEDs of Main Reducer Gearbox Temperature compared with other running mill & found that there was rise in 9°C (approx.) of Coal Mill 1CD Main Reducer. In view of Steep increasing trend of all parameters, it was decided to stop Coal Mill for replacement of Pinion bearings & Main Reducer Gearbox jointly. During maintenance pinion bearing clearances observed on higher side. Main Reducer Input & Intermediate bearings rollers found damaged. Thorough Inspection of Main Reducer GB was carried out in presence of OEM expert. The condition of all gear teethes & shaft found OK. Vibration Analysis, Noise & Ultrasonic Monitoring helped in diagnosing the exact root cause of abnormity in advance thus avoided the catastrophic failure which could have caused total cost of ￡ 122,614.