Eight solutions to the vibration fault of the hott

2022-08-26
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Eight solutions to the vibration fault of the regulating valve

1) the method of increasing stiffness

for oscillation and slight vibration, the stiffness can be increased to eliminate or weaken, such as selecting a spring with large stiffness, changing to a piston actuator and other methods are feasible

2) increasing damping method

increasing damping means increasing the friction against vibration. For example, the valve plug of sleeve valve can be sealed with "O" ring, and graphite packing with large friction can be used, which still has a certain effect on eliminating or weakening slight vibration

3) increase the guide size and reduce the fitting clearance method

generally, the guide size of shaft plug valves is small, and the fitting clearance of all valves is generally large, with 0.4 ~ 1mm, which is helpful to produce mechanical vibration. Therefore, in case of slight mechanical vibration, the vibration can be weakened by increasing the guide size and reducing the fitting clearance

4) change the shape of the throttle and eliminate resonance method

because the so-called vibration source of the regulating valve occurs at the throttle port with high-speed flow and sharp pressure changes, changing the shape of the throttle can change the frequency of the vibration source, which is easier to solve when the resonance is not strong. The specific method is to turn the valve core surface within the range of vibration opening by 0.5 ~ 1.0mm. For example, a self operated pressure regulating valve was installed near the family area of a factory, and the roar caused by resonance affected the rest of employees. After we dropped the valve core surface by 0.5mm, the resonant roar disappeared

5) replace the throttling element to eliminate resonance method

the methods are: ① replace the flow characteristics, change the logarithm to linearity, and change the linearity to logarithm; ② Change the valve element type. For example, change the shaft plug shape to 2. The required man-machine interface is intuitive and friendly, and the allowable tolerance of load or stiffness is abnormally close to the "V" groove spool, and change the double seat valve shaft plug type to the sleeve type; Change the sleeve opening the window into a sleeve with a small hole, etc. For example, a DN25 double seat valve in a nitrogenous fertilizer plant often vibrates and breaks at the connection between the valve stem and the valve core. After we confirm that it is resonance, we change the linear characteristic valve core to the logarithmic valve core, and the problem is solved. Another example is that a DN200 sleeve valve is used in the laboratory of an aeronautical college, and the valve plug cannot be put into use due to strong rotation. After changing the sleeve with a window to a sleeve with a small hole, the rotation disappears immediately

6) change the type of regulating valve to eliminate resonance

the natural frequencies of regulating valves with different structural forms are naturally different. Changing the type of regulating valve is the most effective way to fundamentally eliminate resonance. The resonance of a valve in use is very strong - a valve with strong vibration (which can destroy the valve in serious cases), strong rotation (even the valve rod is broken and twisted), and strong noise (up to more than 100 decibels), as long as it is replaced with a valve with large structural differences, it will take effect immediately, and the strong resonance will miraculously disappear. For example, a DN200 sleeve valve is selected for the new expansion project of a vinylon plant, and the above three phenomena exist. The DN300 pipeline jumps with it, the valve plug rotates, the noise is more than 100 dB, and the resonance opening is 20 ~ 70%. Considering the large resonance opening, after using a double seat valve, the resonance disappears and the operation is normal

7) reducing cavitation vibration method

it is very important for the temperature of turbine head die caused by cavitation bubble rupture to control the surface finish and size of diaphragm. Therefore, it is natural to find ways to reduce cavitation. ① The impact energy generated by bubble rupture does not act on the solid surface, especially on the valve core, but is absorbed by the liquid. Sleeve valve has this feature, so the shaft plug type spool can be changed to sleeve type. ② Take all measures to reduce cavitation, such as increasing throttling resistance, increasing necking pressure, grading or series decompression, etc. Flange ball valve

8) avoid the vibration source wave shock method

the valve vibration caused by the external vibration source wave shock, which obviously should be avoided during the normal operation of the regulating valve. If this vibration occurs, corresponding measures should be taken

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