CASE STUDY ANALYSIS OF PROCESS FAN FAILURE AND BEARING HOUSING/SHAFT DESIGN

摘要

An Air Movement and Control Association (AMCA) Arrangement 8 fan handling hot process gas experienced several bearing failures and ultimately a catastrophic failure requiring shutdown of the plant's production. The investigation found that the 1st critical of the fan rotor was too close to the operating speed resulting in excessive bearing loads and short bearing life. Rotor dynamic modeling was used to evaluate a new shaft design. A new shaft and one-piece bearing housing were designed, fabricated and installed, successfully moving the critical speed several hundred RPM above running speed. The new design also provided improved maintainability over commercially available designs, as well as lowering vibration and significantly improving reliability. This article discusses the analysis process, rotor modeling, bearing housing design process, vibration data comparison before and after the new shaft and bearing housing were installed.