Solutions To Control Valve Vibration--II

Solutions To Control Valve Vibration--II

05 Replacing the throttle to eliminate resonance method

The methods are: change the flow characteristics, change the logarithm to linear, and change the linear to logarithm; change the spool form. For example, change the shape of the shaft plug to a "V"-shaped groove valve core, change the shaft plug type of the double seat valve to a sleeve type; change the sleeve with a window to a sleeve with a small hole, etc.

For example, a DN25 double-seat valve in a nitrogen fertilizer plant often vibrated at the connection between the stem and the valve core. After we confirmed the resonance, the linear characteristic valve core was changed to a logarithmic valve core, and the problem was solved. Another example is the use of a DN200 sleeve valve in the laboratory of an aviation college. The valve plug rotates strongly and cannot be used. After the sleeve with the window is changed to the sleeve with small holes, the rotation disappears immediately.

06 Change the control valve type to eliminate resonance

Regulating valves of different structures have different natural frequencies. Changing the type of regulating valve is the most effective way to fundamentally eliminate resonance.

A valve resonates very badly in use-it vibrates strongly (the valve can be destroyed in severe cases), rotates strongly (even the valve stem is broken or twisted), and produces strong noise (up to more than 100 decibels) As long as you replace it with a valve with a large difference in structure, it will take effect immediately, and the strong resonance will miraculously disappear.

For example, if a DN200 sleeve valve is selected for a new expansion project of a vinylon plant, the above three phenomena exist, the DN300 pipeline will jump, the valve plug will rotate, the noise will be more than 100 decibels, and the resonance opening will be 20-70%. Consider the resonance opening. After switching to a double-seat valve, the resonance disappeared and the operation was normal.

07 Reduce cavitation vibration method

For the cavitation vibration caused by the rupture of the cavitation bubble, it is natural to find a way to reduce the cavitation. The impact energy generated by the bubble burst does not act on the solid surface, especially the valve core, but is absorbed by the liquid. Sleeve valve has this feature, so the plug type spool can be changed to a sleeve type. Take all measures to reduce cavitation, such as increasing the throttling resistance, increasing the pressure at the orifice, grading or series decompression, etc.

08 Avoid vibration source wave strike method

The shock of the external vibration source causes the valve to vibrate, which obviously should be avoided during the normal operation of the regulating valve. If such vibration occurs, corresponding measures should be taken.