AN END-USER’S GUIDE TO CENTRIFUGAL PUMP ROTORDYNAMICS

摘要

This tutorial outlines the basics of pumprnrotordynamics in a form that is intended to bernMachinery End User friendly. Key concepts will berndefined in understandable terms, and analysis andrntesting options will be presented in summary form.rnThe presentation will explain the reasoning behind thernAPI-610 rotor and structural vibration evaluationrnrequirements, and will summarize key portions ofrnAPI-684 “API Standard Paragraphs CoveringrnRotordynamics” as it applies to centrifugal pumps.rnPump rotordynamic problems, including the bearingrnand seal failure problems that they may cause, arernresponsible for a significant amount of thernmaintenance budget and lost-opportunity cost at manyrnrefineries and electric utilities. This tutorial discussesrnthe typical types of pump rotordynamic problems, andrnhow they can be avoided in most cases by applyingrnthe right kinds of vibration analysis and evaluationrncriteria during the pump design and selection/rnapplication process. Although End Users seldom arerndirectly involved in designing a pump, it is becomingrnmore typical that the reliability-conscious End User orrnhis consultant will audit whether or not the OEM hasrnperformed due diligence in the course of his pumprndesign. In the case of rotordynamics, important issuesrninclude where the pump is operating on its curvern(preferably close to BEP), how close the pump rotorrncritical speeds and rotor-support structural naturalrnfrequencies are to running speed or other forcingrnfrequencies, how much vibration will occur atrnbearings or within close running clearances forrnexpected worst case imbalance and misalignment, andrnwhether or not the rotor system is likely to behave in arnstable, predictable manner.rnWhen and why rotordynamics analysis or finiternelement analysis might be performed will berndiscussed, as well as what kinds of information thesernanalyses can provide to an end user that could berncritical to reliable and trouble-free operation. Arnspecific case history will be presented in the context ofrntypical or particularly problematic situations thatrnplants have faced, and what types of solutions wererneffective at inexpensively providing a permanent fix.