Dynamic Characteristics Analysis And Structural Optimization Design Of Decanter Centrifuge

The horizontal decanter centrifuge is a kind of centrifugal settling and separation equipment which is used in extensive areas.As a kind of rotary machine with dual-rotors,the inner rotor is the screw and the outer rotor is the bowl.The vibration problem is always an obstacle that baffles the development of decanter centrifuge.For a certain type of decanter centrifuge,numerical analysis and comprehensive vibration tests are conducted to study the main vibration faults and vibration characteristics of the decanter centrifuge which have certain significance for the structure design of the decanter centrifuge.Vibration tests under no-load conditions on the characteristics of the decanter centrifuge are carried,including the start-up process of vibration test and load condition of stable speed vibration testing and process of stopping vibration testing.Applying domain diagram,amplitude frequency spectrum,orbit and frequency spectrum diagram to analyze the vibration characteristics of the decanter centrifuge and the critical speed is 4833 r/min.Results show that the determination of secondary critical speed method to estimate the critical speed of the decanter centrifuge is safe and effective,also due to the drum and screw in differential speed,the vibration will be accompanied by “beat”,which makes the danger of decanter centrifuge vibration more high,failure can be more.The 3D finite element model of rotor system of decanter centrifuge is established by using finite element software method.The dynamic frequency,critical speed and the corresponding mode shapes of bowl,screw,and the rotor system under different condition are got in the modal analysis module.And the influence of material parameters on the critical speed of decanter centrifuge was discussed.The results show that the coupled rotor system of the first critical speed below the corresponding parts of the bowl and screw the order critical speed,the coupled rotor system vibration type and bowl and screw dynamic modes of frequency from high to low order of the corresponding one-to-one correspondence.The critical speed of the rotor system under no load condition is 4914.2r/min and the critical speed of the rotor system under no load condition is 4857.7r/min,the difference is 1.15%.On the basis of numerical simulation of the rotor system of the decanter centrifuge,simulating the whole machine for rotor system dynamic analysis under load condition in the mode analysis module harmonic response analysis module.The machine of the critical speed and the corresponding mode shape and unbalance response characteristics are obtained.And the influence of structural parameters for the seat of the critical speed of the decanter centrifuge is discussed.The results show that the different order modes of the horizontal screw centrifuge are in agreement with the corresponding vibration modes of the components.The lowest order critical speed of the rotor system is determined by the lowest part of the stiffness.After optimization,the vibration of the whole machine under normal conditions is reduced from the original 6.0mm/s to 3.4mm/s,a decline of 43%,the optimization effect is obvious.The results of the study have certain significance for the structure design,high speed dynamic balance and vibration diagnosis of the decanter centrifuge.