Introduce the valve in the regulator vibration analysis and solution

by：J&T     2020-07-01
One, the regulator of the vibration and noise according to the induced factors, can be roughly divided into mechanical vibration, cavitation and fluid dynamics vibration and other reasons. 1, fluid dynamics, vibration: medium inside the valve throttling process as well as the process of the friction, the resistance and disturbance. Turbulence body formed by bad fluid around the regulator with spiral, spiral will fall off with the drafting of the continued flow of fluid. The formation of the vortex shedding frequency and the influence factors are complicated, and there is a lot of randomness, quantitative calculation is very difficult, and fall off objective has a dominant frequency. When the dominant loss frequency ( Also includes higher harmonic) And its affiliated with the regulator device close to the structure of the frequency or consistent, resonance happens, the vibration of the regulating valve is accompanied by noise. The strength of the vibration strength falls off with the dominant frequency and higher harmonic wave direction and the degree of consistency. 2, mechanical vibration, according to its form of expression can be divided into two states. A state is a regulator of the overall vibration, namely the regulator in the pipe or fibrillation frequently, the reason is because the pipeline or base violent vibration, vibration caused the regulator. Also related to the frequency, that is, when the frequency of the external and the system is equal or close to the natural frequency of the energy of the forced vibration achieve greater value, resonate. Another state is the vibration of the regulator valve, the main reason is due to the rapid increase of medium velocity, the regulating valve before and after the differential change sharply, cause the regulator to produce severe oscillation. 3, cavitation inside the regulator of vibration occurs mostly in liquid medium. The fundamental cause of cavitation is contracted flow regulator within the fluid acceleration and static pressure drop of liquid. Before and after the valve opening is smaller, the pressure difference, the greater the flow speed and the greater the likelihood of cavitation, and the matching block the flow and the smaller the pressure drop. Second, the solution 1, increase guide size, reduce the tolerance clearance method; Shaft to the small size plug valve general orientation, all valve fitting clearance are generally bigger, have 0. 4 ~ LMM, which is helpful to produce mechanical vibration. Therefore, in the event of a minor mechanical vibration, can guide by increasing size, reduce the tolerance clearance to weaken vibration. The shape of the 2, change the throttling, dissolve the resonance method; Because of the so-called source of the regulating valve in high speed flow, rapid pressure changes of the throttle opening, change the shape of the throttling parts can change the source of vibration frequency, are easy to solve resonance is not strong. Specific measures will be in the opening of the vibration is within the scope of the valve core surface turning 0. 5 ~ 1. 0mm。 3, increase the stiffness method; Of oscillation and slight vibration, can increase the stiffness to eliminate or reduced, if choose takong degrees of spring, to switch to the way such as piston actuators are feasible. 4, replacement valve type to eliminate resonance; Different structural forms of the regulator, and its natural frequency, natural replacement valve type fundamentally eliminate the resonance of the effective methods. A valve in the use of resonance is powerful & ndash; — — Strongly vibration ( Serious when valve damage) can be , strongly rotation ( Even stem by strikes, twist off) And a strong noise ( As high as 100 decibels) The valve, as long as to change it into a structural differences in the larger valve, effective immediately, strong resonance miraculously disappeared. As a vinylon plant a DN200 sleeve valve is used in the new expansion project, the above three kinds of phenomena exist, 12 pipeline, then rotate the plug, more than 100 db noise, resonant opening 20 ~ 70%, considering the resonance opening, after using a two-seater valve, resonance, put into operation normally. 5, reducing cavitation vibration method; For cavitation bubble burst and the cavitation vibration, nature should be to find a way to reduce cavitation. (1) the effects of the impact energy is not allow bubble burst in the solid surface, especially on the valve core, but let the fluid absorption. Sleeve valve has the features, so can change type shaft plug valve core to sleeve type. (2) all the way to reduce cavitation, such as increased thermal resistance, increase LiuKou pressure, classification or series reduced pressure, etc. 6, to avoid the vibration source wave method; Wave blow valve vibration caused by the external source, it's clearly a regulating valve during normal work should be avoided, if the vibration of the corresponding measures should be taken. 7, increasing the damping method; The increase of vibration friction, such as sleeve valve plug can be used & other O” Ring seal, with larger friction graphite packing, etc. , to eliminate or weaken the slight vibration or have certain effect. 8, replacing throttling eliminate resonance method (1) change the flow characteristic, logarithm change linear, linear change log; (2) replacement of valve core. If changes will shaft plug & other; V” Trough the valve core, the two-seater type valve shaft plug into a socket; Will open a window of the sleeve to play holes of sleeve, etc.
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