Vibration reliability and endurance of a centrifuge for separating suspensions

Abstract

A model of a centrifuge is developed, critical centrifuge speeds are determined by the Dunkerley and Krylov method, and the expected endurance with centrifuge vibration is determined.In the design, manufacture, and operation of centrifugal equipment, evaluation of their vibration reliability is recommended in order to provide accident-free operation. Here, a knowledge of the range of critical velocities, expected life with vibration, makes it possible to optimize the construction parameters of a device so that during its operation resonance phenomena are avoided, that lead to total breakdown of the device, and also to reduce development costs due to a reduction in the number of full-scale tests [1][2][3][4].Vibration reliability theory describes common approaches to analytical study of vibratory systems with a finite number of degrees of freedom and linear systems with distribution parameters, and also for determining the form and values of natural frequency vibrations of a complex structure. Additional studies should be carried out for a specific device, mechanism or class of devices.Well-known methods for evaluating the vibration reliability of centrifugal devices [1-5] are common for a whole variety of rotary machines. However, these methods do not make it possible, for example, to construct a simple mathematical model for evaluating the range of most probable critical velocities and the number of outbursts in a unit of time specifically for a loaded centrifuge of the vertical type, intended for separating suspensions by centrifugal deposition [1,6,7]. This centrifuge is related to continuously operating machines with inertial discharge of deposit. It may be used in the chemical and petrochemical industries for extracting solid deposits and suspensions of liquid media, and separation of medium-and highly-concentrated suspensions [6][7][8][9][10][11].The aim of this work is a study of the parameters of vibration reliability (range of critical velocities and expected life with vibration) of a loaded centrifuge of the vertical type for separating suspensions, development of a simple model for calculating these parameters, implemented in a personal computer, and also checking this model for conformity with experimental data with full-scale tests.The terms and definitions used herein are provided in [1,3,4,[12][13][14][15][16]. Mathematical Model of CentrifugeThe shaft of a centrifuge is placed on two supports. At the free end of the shaft through a rod a collector is fastened, that is a hollow thin-walled cylinder with an open lower base for loading a suspension and four holes in a cylindrical shell for discharge of clarified liquid. The center of gravity of the collector does not coincide with the area of its fastening to the shaft.

Optimization of Highly-Structured Mechanical Systems with Abnormal Functioning through the Example of a Precipitation Centrifugation of Powder Precipitates

“…Based on the results of the examination of centrifugal vibration reliability [1][2][3], a mathematical model of precipitation centrifuging is plotted to determine the mass of collected precipitate Ф taking into account a practically observed decrease in the centrifuge performance due to the random deviation of the mass center from the rotation axis.…”

“…The Dunkerley method was used to plot the models and calculate the vibration reliability parameters [1][2]4]; the Оrnstein -Uhlenbесk process [5] as well as the minimax criterion were used to determine the optimal rotation frequency of the vertical submersing centrifuge shaft. The adequacy of the model was checked by comparing the data of the in-situ test and computational experiment as well as empirical distribution function based on the generated data.…”

“…The mathematical and simulation modeling [1][2][3] play an important role in the study of the performance, reliability and service life of centrifuges used for the precipitation processes.…”