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金沙国际登陆 > 技术文章 > 电动实行器流量特性不匹配将会如何

电动实行器流量特性不匹配将会如何

2018-10-04

电动实行器流量特性不匹配将会如何 
What happens to the mismatch of the valve electric device flow characteristics?


电动实行器控制阀的流量特性用于补偿被控对象的不同特性。如果选配的流量特性不合适,会使控制系统的控制品质变差。例如,在小流量和大流量时,控制系统的灵敏度不同。天蝶阀门专业故障分析如下
The flow characteristics of the control valve are used to compensate for the different characteristics of the controlled object. If the matching flow characteristics are not suitable, the control quality of the control system will be degraded. For example, the sensitivity of the control system is different at low flow rates and high flow rates. The failure analysis is as follows.

罗托克电动实行器

(角行程罗托克电动实行器)

1.被控对象具有饱和非线性特性(例如,温度控制系统)小流量时,控制系统能够正常运行,但大流量时控制系统呆滞。或小流量时控制系统极灵敏,甚至出现振荡和不稳定,但在大流量时,控制系统能够正常运行。故障原因是选用了线性或快开流量特性控制阀。故障处理方法是更换控制阀的阀内件或控制阀,或安装阀f刁定位器,使控制阀满足等百分比或抛物线流量特性要求。
1. The controlled object has a saturated nonlinear characteristic (for example, the temperature control system). At low flow rate, the control system can operate normally, but at high flow rate, the control system becomes sluggish. And at low flow rates, the control system is extremely sensitive and even occurs oscillation and instability. However, at high flow rates, the control system can operate normally. The cause of the failure is the use of a linear or fast opening flow characteristic control valve. The troubleshooting method is to replace the inner part of control valve or the control valve, or to install the valve f locator, so that the control valve meets the requirements of equal percentage or parabolic flow characteristics.

伯纳德电动实行器

(角行程伯纳德电动实行器)

2.被控对象具有线性特性(例如,流量随动控制系统)o小流量时控制系统运行正常,大流量时控制系统出现振荡或不稳定现象。或小流量时控制系统呆滞,大流量时控制系统能够正常运行。故障原因是选用了等百分比或抛物线流量特性控制阀。故障处理方法是更换控制阀的阀内件或控制阀,或安装阀门定位器,使控制阀满足线性流量特性要求。
2. The controlled object has a linear characteristic (for example, the flow servo control system). At low flow rate, the control system operates normally. At high flow rate, the control system occurs oscillation and instability. Or at low flow rate, the control system is sluggish, at high flow rate, the control system can operate normally. The cause of the failure is the use of an equal percentage or parabolic flow characteristic control valve. The troubleshooting method is to replace the inner part of control valve or the control valve, or to install the valve f locator, so that the control valve meets the requirements of linear flow characteristics.

QT电动实行器

(角行程QT电动实行器)

3.控制阀额定流量系数选择不当。选用的额定流量系数过大或过小,使控制阀可调节的小或大流量变大或变小,不能满足工艺生产过程的操作要求。控制阀工作在小开度或大开度位置,控制品质变差。故障处理方法是重新核算控制阀流量系数,安装符合要求的控制阀。例如,直接根据工艺管道直径选配控制阀造成额定流量系数过大,由于生产规模扩大造成额定流量系数过小等。
3. Improper selection of control valve rated flow coefficient. If the selected rated flow coefficient is too large or too small, the minimum or maximum flow rate that can be adjusted by the control valve becomes larger or smaller, which cannot meet the operational requirements of the process. The control valve operates at a small opening or a large opening, the control quality will become worse. The troubleshooting method is to recalculate the flow coefficient of the control valve and install a control valve that meets the requirements. For example, directly selecting the control valve according to the diameter of the process pipe will cause the rated flow coefficient to be too large. And as the scale of production increases, the rated flow coefficient will be too small.
流路设计和安装不当造成的故障
Failures caused by improper design and installation of flow path
电动实行器控制阀流路设计或安装不当造成故障表现为噪声增大,污物容易积聚在阀体内部,使控制阀关闭不严,泄漏量增大或卡死等。故障分析如下。
Due to the improper design or installation of the control valve flow path, the fault is manifested the increase of noise. Contaminants tend to accumulate in the valve body, causing the control valve to close loosely, increasing the leakage, or getting stuck. The failure analysis is as follows.
1.双座阀泄漏量增大。双座阀未采用一体化设计,造成温度变化时阀内件膨胀系数不同而使泄漏量增大。故障处理方法是选用一体化双座阀,或选用具有平衡功能的套筒阀。
1. Double seat valve leakage increases. The double seat valve does not use an integrated design, resulting in a different expansion coefficient of the valve inner part when the temperature is changed, so that the leakage amount increases. The fault treatment method is to use an integrated double seat valve or a sleeve valve with balanced functions.
2.三通阀用于合流时,由于合流的两股流体温度不同造成泄漏量增大。故障处理方法是将流体的合流改为分流控制,安装三通阀在换热器前,从而保证流体温度一致o
2. When the three-way valve is used for confluence, the amount of leakage increases due to the difference in the temperature of the two streams confluent. The fault treatment method is to change the confluence of fluids to split flow control and install the three-way valve in front of the heat exchanger so as to ensure the consistent fluid temperature.
3.流向不当造成噪声增大。例如,流开控制阀用于流关场合,造成小流量时的噪声增大。故障处理方法是检查流向,重新安装。
3. Improper flow direction will increase noise. For example, flow-through control valves are used in flow-off applications, resulting in increased noise at small flow rates. The troubleshooting method is to check the flow direction and reinstall it.
4.上、下游切断阀与电动实行器旁路阀安装不当。造成污物、冷凝液或不凝性气体不能排放。故障处理方法是排污阀安装在控制阀组的低处,放空阀安装在控制阀组的顶端。
4. The improper installation of the upstream and downstream shut-off valves and the bypass valve will cause the drains, condensate or non-condensable gases cannot be discharged. The troubleshooting method is that the drain valve is installed at the lowest position of the control valve group, and the blow-off valve is installed at the highest position of the control valve group.
5.导向轴套安装不当。造成中心未对准,使摩擦增大,阀杆卡死。故障处理方法是重新安装导向轴套。
5. The improper installation of the guide shaft sleeve will cause the misalignment of the center and make the friction increases and the stem stuck. The troubleshooting method is to reinstall the guide shaft sleeve.
泄漏量造成的故障
Failure caused by leakage
内泄漏造成可调比下降,严重时使控制系统不能满足工艺操作和控制要求。外泄漏造成环境污染,使成本提高。故障分析如下。
Internal leakage will cause a decrease in the adjustable ratio, which can make the control system unable to meet the process operation and control requirements. External leakage will cause environmental pollution and increase costs. The fault analysis is as follows.
1.因空化和汽蚀造成泄漏量增大。由于空化、闪蒸和汽蚀造成阀芯和阀座损坏,使控制阀的泄漏量增大时表现为气体或液体动力学噪声的增大。故障处理方法是检查阀内件,更换或研磨阀芯、阀座、阀芯堆焊硬质合金,降低控制阀两端压降,消除噪声声源,采用低噪声控制阀等。
1. Cavitation and cavitation will cause an increase in leakage. Due to cavitation, flash evaporation, and cavitation damage to the valve plug and valve seat, the increase in leakage of the control valve is manifested as an increase in gas or liquid dynamic noise. The troubleshooting method is to inspect the valve inner parts, replace or grind the valve core, valve seat, and valve core weld metal, reduce the pressure drop at both ends of the control valve, eliminate noise sources, and use low noise control valves.
2.因被控流体含有杂物造成泄漏量增大。在开车阶段常常因管道吹扫时未将控制阀拆下的不规范操作造成杂物进入控制阀,或在运行过程中,被控流体夹带的杂物积聚在阀体内部,这些杂物造成阀芯与阀座密封面损伤,使泄漏量增大。故障处理方法是研磨阀芯和阀座,在管道吹扫时拆下控制阀,对含颗粒的被控流体,可在控制阀上游安装过滤装置,将控制阀组安装在较高位置,并定期进行排污。
2. The controlled fluid contains impurities that increase the leakage. In the start-up phase, irregular operations that do not remove the control valve when the pipe is purged often cause debris to enter the control valve, or during operation, debris trapped by the controlled fluid accumulates inside the valve body. These debris damage to the valve core and valve seat sealing surface, so that increased leakage. The troubleshooting method is to grind the valve core and valve seat. When the pipeline is purged, the control valve is removed. For the controlled fluid containing particles, a filter device can be installed upstream of the control valve, and the control valve group is installed at a relatively high position and regular discharge must be carried out.
3.电动实行器与电动调节阀构连接不合适。故障处理方法是重新安装,进行泄漏量测试。
3. The electric actuator is not properly connected to the electric control valve. The troubleshooting method is to reinstall it and carry out the leak test.
4.填料安装不当。由于填料安装不当,造成摩擦力增大或使阀杆变形。故障处理方法是重新安装填料,对变形的阀杆整形。
4. Improper installation of the packing. Improper installation of the packing results in increased friction or deformation of the stem. The troubleshooting method is to reinstall the packing and shape the deformed stem.
5.法兰安装不当。造成受力不均引起外泄漏,故障处理方法是重新安装连接法兰和垫片,并均匀用力压紧连接法兰。
5. The flange is not properly installed will cause uneven force and external leakage, the troubleshooting method is to reinstall the connection flange and gasket, and evenly pressed the connection flange.
6.流体流动对阀芯和阀座的磨损。故障处理方法是对阀芯和阀座进行研磨。
6. Fluid flow wears on valve core and valve seat. The troubleshooting method is to grind the valve core and valve seat.
7 .填料安装不当造成摩擦增大,控制阀关不严造成外泄漏量增大。故障处理方法是重新安装填料,减小摩擦。
7. Improper installation of packing results in increased friction, and loose control valves cause increased leakage. The troubleshooting method is to reinstall the packing and reduce the friction.
8.流向不当造成泄漏量增大。流向选择不当使不平衡力增大,从而使泄漏量增大。故障处理方法是核对设计图纸,重新安装。
8. Improper flow direction result in increased leakage. Improper selection of flow direction increases the unbalanced force and increases the leakage. The troubleshooting method is to check the design drawings and reinstall them.

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