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        • 電動執行機構
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        首頁 > 技術文章 > 電動執行器流量特性不匹配將會如何

        電動執行器流量特性不匹配將會如何

        2018-10-04

        電動執行器流量特性不匹配將會如何 
        What happens to the mismatch of the valve electric device flow characteristics?


        電動執行器控制閥的流量特性用于補償被控對象的不同特性。如果選配的流量特性不合適,會使控制系統的控制品質變差。例如,在小流量和大流量時,控制系統的靈敏度不同。天蝶閥門專業故障分析如下
        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.

        (角行程羅托克電動執行器)

        1.被控對象具有飽和非線性特性(例如,溫度控制系統)小流量時,控制系統能夠正常運行,但大流量時控制系統呆滯?;蛐×髁繒r控制系統極靈敏,甚至出現振蕩和不穩定,但在大流量時,控制系統能夠正常運行。故障原因是選用了線性或快開流量特性控制閥。故障處理方法是更換控制閥的閥內件或控制閥,或安裝閥f刁定位器,使控制閥滿足等百分比或拋物線流量特性要求。
        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.

        (角行程伯納德電動執行器)

        2.被控對象具有線性特性(例如,流量隨動控制系統)o小流量時控制系統運行正常,大流量時控制系統出現振蕩或不穩定現象?;蛐×髁繒r控制系統呆滯,大流量時控制系統能夠正常運行。故障原因是選用了等百分比或拋物線流量特性控制閥。故障處理方法是更換控制閥的閥內件或控制閥,或安裝閥門定位器,使控制閥滿足線性流量特性要求。
        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.

        (角行程QT電動執行器)

        3.控制閥額定流量系數選擇不當。選用的額定流量系數過大或過小,使控制閥可調節的小或大流量變大或變小,不能滿足工藝生產過程的操作要求??刂崎y工作在小開度或大開度位置,控制品質變差。故障處理方法是重新核算控制閥流量系數,安裝符合要求的控制閥。例如,直接根據工藝管道直徑選配控制閥造成額定流量系數過大,由于生產規模擴大造成額定流量系數過小等。
        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.
        流路設計和安裝不當造成的故障
        Failures caused by improper design and installation of flow path
        電動執行器控制閥流路設計或安裝不當造成故障表現為噪聲增大,污物容易積聚在閥體內部,使控制閥關閉不嚴,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.雙座閥泄漏量增大。雙座閥未采用一體化設計,造成溫度變化時閥內件膨脹系數不同而使泄漏量增大。故障處理方法是選用一體化雙座閥,或選用具有平衡功能的套筒閥。
        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.
        2.三通閥用于合流時,由于合流的兩股流體溫度不同造成泄漏量增大。故障處理方法是將流體的合流改為分流控制,安裝三通閥在換熱器前,從而保證流體溫度一致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.流向不當造成噪聲增大。例如,流開控制閥用于流關場合,造成小流量時的噪聲增大。故障處理方法是檢查流向,重新安裝。
        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、下游切斷閥與電動執行器旁路閥安裝不當。造成污物、冷凝液或不凝性氣體不能排放。故障處理方法是排污閥安裝在控制閥組的低處,放空閥安裝在控制閥組的頂端。
        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.導向軸套安裝不當。造成中心未對準,使摩擦增大,閥桿卡死。故障處理方法是重新安裝導向軸套。
        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
        內泄漏造成可調比下降,嚴重時使控制系統不能滿足工藝操作和控制要求。外泄漏造成環境污染,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.因空化和汽蝕造成泄漏量增大。由于空化、閃蒸和汽蝕造成閥芯和閥座損壞,使控制閥的泄漏量增大時表現為氣體或液體動力學噪聲的增大。故障處理方法是檢查閥內件,更換或研磨閥芯、閥座、閥芯堆焊硬質合金,降低控制閥兩端壓降,消除噪聲聲源,采用低噪聲控制閥等。
        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.因被控流體含有雜物造成泄漏量增大。在開車階段常常因管道吹掃時未將控制閥拆下的不規范操作造成雜物進入控制閥,或在運行過程中,被控流體夾帶的雜物積聚在閥體內部,這些雜物造成閥芯與閥座密封面損傷,使泄漏量增大。故障處理方法是研磨閥芯和閥座,在管道吹掃時拆下控制閥,對含顆粒的被控流體,可在控制閥上游安裝過濾裝置,將控制閥組安裝在較高位置,并定期進行排污。
        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.電動執行器與電動調節閥構連接不合適。故障處理方法是重新安裝,進行泄漏量測試。
        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.填料安裝不當。由于填料安裝不當,造成摩擦力增大或使閥桿變形。故障處理方法是重新安裝填料,對變形的閥桿整形。
        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.法蘭安裝不當。造成受力不均引起外泄漏,故障處理方法是重新安裝連接法蘭和墊片,并均勻用力壓緊連接法蘭。
        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.流體流動對閥芯和閥座的磨損。故障處理方法是對閥芯和閥座進行研磨。
        6. Fluid flow wears on valve core and valve seat. The troubleshooting method is to grind the valve core and valve seat.
        7 .填料安裝不當造成摩擦增大,控制閥關不嚴造成外泄漏量增大。故障處理方法是重新安裝填料,減小摩擦。
        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.流向不當造成泄漏量增大。流向選擇不當使不平衡力增大,從而使泄漏量增大。故障處理方法是核對設計圖紙,重新安裝。
        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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