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调节阀振动原因分析及方式

来源: //www.rabieb.com/日期:2024-01-22 发布人:创始人

一、振动原因分析:

1、 Vibration cause analysis:

调节阀的振动与噪声根据其诱发因素不同,大致可分为机械振动、气蚀振动和流体动力学振动等原因。

The vibration and noise of regulating valves can be roughly divided into mechanical vibration, cavitation vibration, and fluid dynamics vibration based on their triggering factors.

机械振动:

Mechanical vibration:

机械振动根据其表现形式可以分为两种状态。一种状态是调节阀的整体振动,即整个调节阀在管道或基座上频繁颤动,其原因是由于管道或基座剧烈振动,引起整个调节阀振动。此外还与频率有关,即当外部的频率与系统的固有频率相等或接近时受迫振动的能量达到大值、产生共振。另一种状态是调节阀阀瓣的振动,其原因主要是由于介质流速的急剧增加,使调节阀前后差压急剧变化,引起整个调节阀产生严重振荡。

Mechanical vibration can be divided into two states based on its manifestation. One state is the overall vibration of the regulating valve, that is, the entire regulating valve frequently vibrates on the pipeline or base, due to severe vibration of the pipeline or base, causing the entire regulating valve to vibrate. In addition, it is also related to frequency, that is, when the external frequency is equal to or close to the natural frequency of the system, the energy of forced vibration reaches a maximum value and resonance occurs. Another state is the vibration of the regulating valve disc, which is mainly caused by the sharp increase in medium flow rate, causing a sharp change in the differential pressure before and after the regulating valve, causing serious oscillation of the entire regulating valve.

气蚀振动:

Cavitation vibration:

气蚀振动大多发生在液态介质的调节阀内。气蚀产生的根本原因在于调节阀内流体缩流加速和静压下降引起液体汽化。调节阀开度越小,其前后的压差越大,流体加速并产生气蚀的可能性就越大,与之对应的阻塞流压降也就越小。

Cavitation vibration mostly occurs inside the regulating valve of liquid media. The fundamental cause of cavitation is the acceleration of fluid contraction and the decrease in static pressure inside the regulating valve, which causes liquid vaporization. The smaller the opening of the regulating valve, the greater the pressure difference before and after it, the greater the possibility of fluid acceleration and cavitation, and the corresponding blockage flow pressure drop.

流体动力学振动:

Fluid dynamics vibration:

介质在阀内的节流过程也是其受摩擦、受阻力和扰动的过程。湍流体通过不良绕流体的调节阀时形成旋涡,旋涡会随着流体的继续流动的尾流而脱落。这种旋涡脱落频率的形成及影响因素十分复杂,并有很大的随机性,定量计算十分困难,而客观却存在一个主导脱落频率。当这一主导脱落频率(亦包括高次谐波)在与调节阀及其附属装置的结构频率接近或一致时,发生了共振,调节阀就产生了振动,并伴随着噪声。振动的强弱随主导脱落频率的强弱和高次谐波波动方向一致性的程度而定。

The throttling process of the medium inside the valve is also a process of friction, resistance, and disturbance. When turbulent fluid passes through a regulating valve with poor flow around the fluid, it forms a vortex, which will detach as the fluid continues to flow through the wake. The formation and influencing factors of this vortex shedding frequency are very complex and have great randomness, making quantitative calculation very difficult. However, objectively, there exists a dominant shedding frequency. When the dominant shedding frequency (including high-order harmonics) is close to or consistent with the structural frequency of the regulating valve and its accessories, resonance occurs, and the regulating valve produces vibration accompanied by noise. The strength of vibration depends on the strength of the dominant shedding frequency and the degree of consistency in the direction of high-order harmonic fluctuations.

二、方案:

2、 Solution:

从调节阀的使用和理论分析可以证明,诱发调节阀振动和噪声的因素有很多,这些因素又相互影响,很多都是同时发生的,这就使调节阀的减震降噪更加困难,需要结合阀门材质、结构和流体动力学等方面综合考虑。

From the use and theoretical analysis of regulating valves, it can be proven that there are many factors that induce vibration and noise in regulating valves, and these factors affect each other, many of which occur simultaneously. This makes it more difficult to reduce vibration and noise in regulating valves, and requires comprehensive consideration of valve material, structure, and fluid dynamics.

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(1)增加刚度法 :

(1) Increasing stiffness method:

对振荡和轻微振动,可增大刚度来或减弱,如选用大刚度的弹簧,改用活塞执行机构等办法都是可行的。

For oscillations and slight vibrations, increasing stiffness can be used to eliminate or weaken them. Methods such as using high stiffness springs or switching to piston actuators are feasible.

增加阻尼法 :

Increase damping method:

增加阻尼即增加对振动的摩擦,如套筒阀的阀塞可采用“O”形圈密封,采用具有较大摩擦力的石墨填料等,这对或减弱轻微的振动还是有一定作用的。

Increasing damping means increasing friction against vibration. For example, the valve plug of a sleeve valve can be sealed with an "O" ring, and graphite packing with high friction can be used. This can still have a certain effect on eliminating or weakening slight vibrations.

(3)增大导向尺寸,减小配合间隙法 :

(3) Increase the guiding dimension and reduce the fit clearance method:

轴塞形阀一般导向尺寸都较小,所有阀配合间隙一般都较大,有0.4~lmm,这对产生机械振动是有帮助。因此,在发生轻微的机械振动时,可通过增大导向尺寸,减小配合间隙来削弱振动。

Axial plug valves generally have smaller guiding dimensions, and all valve clearances are generally larger, ranging from 0.4 to 1mm, which is helpful for generating mechanical vibration. Therefore, when slight mechanical vibration occurs, the vibration can be weakened by increasing the guide size and reducing the fit clearance.

(4)改变节流件形状,共振法 :

(4) Change the shape of the throttle element and eliminate resonance method:

因调节阀的所谓振源发生在高速流动、压力急剧变化的节流口,改变节流件的形状即可改变振源频率,在共振不强烈时比较容易。具体办法是将在振动开度范围内阀芯曲面车削0.5~1.0mm。如某厂家属区附近安装了一台自力式压力调节阀,因共振产生啸叫影响职工休息,我们将阀芯曲面车掉0.5mm后,共振啸叫声消失。

The so-called vibration source of the regulating valve occurs at the throttling port with high-speed flow and rapid pressure changes. Changing the shape of the throttling component can change the frequency of the vibration source, which is relatively easy to solve when the resonance is not strong. The specific method is to turn the curved surface of the valve core within the range of vibration opening by 0.5-1.0mm. A self operated pressure regulating valve was installed near the residential area of a certain factory, and due to resonance, it caused a whistling sound that affected the rest of employees. After we lowered the curved surface of the valve core by 0.5mm, the resonance whistling sound disappeared.

(5)更换节流件共振法 :

(5) Replacing throttle components to eliminate resonance method:

①更换流量特性,对数改线性,线性改对数

① Change flow characteristics, logarithmic to linear, linear to logarithmic

②更换阀芯形式。

② Replace the valve core form.

如将轴塞形改为“V”形槽阀芯,将双座阀轴塞型改成套筒型;将开窗口的套筒改为打小孔的套筒等。

If the plug type is changed to a "V" groove valve core, and the double seat valve plug type is changed to a sleeve type; Change the sleeve for opening windows to a sleeve for punching small holes, etc.

(6)更换调节阀类型以共振:

(6) Change the type of regulating valve to eliminate resonance:

不同结构形式的调节阀,其固有频率自然不同,更换调节阀类型是从根本上共振的有效的方法。一台阀在使用中共振十分厉害———强烈地振动(严重时可将阀破坏),强烈地旋转(甚阀杆被振断、扭断),而且产生强烈的噪音(高达100多分贝)的阀,只要把它更换成一台结构差异较大的阀,立刻见效,强烈共振奇迹般地消失。如某维尼纶厂新扩建工程选用一台DN200套筒阀,上述三种现象都存在,DN300的管道随之跳动,阀塞旋转,噪音100多分贝,共振开度20~70%,考虑共振开度大,改用一台双座阀后,共振消失,投运正常。

Different structural forms of regulating valves naturally have different natural frequencies. Changing the type of regulating valve is an effective method to fundamentally eliminate resonance. A valve resonates severely during use - it vibrates strongly (can be damaged in severe cases), rotates strongly (even the valve stem is broken or twisted), and produces strong noise (up to over 100 decibels). As long as it is replaced with a valve with a significant structural difference, it immediately takes effect, and the strong resonance miraculously disappears. If a new expansion project of a certain Vinylon factory uses a DN200 sleeve valve, all three phenomena mentioned above exist. The DN300 pipeline jumps, the valve plug rotates, the noise is over 100 decibels, and the resonance opening is 20-70%. Considering the large resonance opening, after switching to a double seat valve, the resonance disappears and is put into normal operation.

减小汽蚀振动法 :

Reducing cavitation vibration method:

对因空化汽泡破裂而产生的汽蚀振动,自然应在减小空化上想办法。①让气泡破裂产生的冲击能量不作用在固体表面上,特别是阀芯上,而是让液体吸收。套筒阀就具有这个特点,因此可以将轴塞型阀芯改成套筒型。②采取减小空化的一切办法,如增加节流阻力,增大缩流口压力,分级或串联减压等。

For the cavitation vibration caused by the rupture of cavitation bubbles, it is natural to find ways to reduce cavitation The impact energy generated by bursting bubbles does not act on the solid surface, especially on the valve core, but is absorbed by the liquid. The sleeve valve has this characteristic, so the plug type valve core can be changed to a sleeve type Take all measures to reduce cavitation, such as increasing throttling resistance, increasing the pressure at the constriction port, grading or series pressure reduction, etc.

避开振源波击法 :

Avoiding source wave impact method:

外来振源波击引起阀振动,这显然是调节阀正常工作时所应避开的,如果产生这种振动,应当采取相应的措施。

External vibration sources can cause valve vibration, which should be avoided during normal operation of the regulating valve. If such vibration occurs, corresponding measures should be taken.

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