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        • 電動執行機構
        • 閘閥、蝶閥
        首頁 > 技術文章 > 調節閥安全運行的因素分析以及電動執行器出廠檢測的注意事項

        調節閥安全運行的因素分析以及電動執行器出廠檢測的注意事項

        2018-09-14

        調節閥安全運行的因素分析以及電動執行器出廠檢測的注意事項
        Analysis of factors affecting the safety operation of regulating valves and precautions for factory inspection of electric actuators

        電站閥門、化工閥門、冶金閥門、高溫高壓閥門、電動執行器以及其他閥門在自動化程度較高的化工控制系統中,調節閥作為自動調節系統的終端執行裝置,接受控制信號實現對化工流程的調節,要求各異,對電磁閥滲漏要求應按有關規定執行。它的動作靈敏度直接關系著調節系統的質量。據現場實際統計有70%左右的故障出自調節閥。因此在日常維護中總結分析影響調節閥安全運行的因素。
         Power station valves, chemical valves, metallurgical valves, high-temperature ,electric atuators and high-pressure valves and other valves are in the chemical control system with high automation, regulating valves are used as terminal actuators for automatic regulating systems to accept control signals to adjust chemical processes. Electromagnetic valve leakage requirements should be implemented in accordance with relevant regulations. Its motion sensitivity is directly related to the quality of the regulating system. According to the actual statistics on the site, about 70% of the faults come from the regulating valve. Therefore, the factors affecting the safe operation of the regulating valve should be summarized and analyzed during routine maintenance.

        1、卡堵
        1. Jamming
        調節閥經常出現的問題是卡堵,常出現在新投運系統和大修投運初期,由于管道內焊渣、鐵銹等在節流口、導向部位造成堵塞使介質流通不暢,或調節閥檢修中填料過緊,造成摩擦力增大,導致小信號不動作大信號動作過頭的現象。
         The regular problem of regulating valves is jamming, which often occurs in the new delivery system and the early stage of overhaul and transportation. Because the welding slag and rust in the pipeline cause blockage at the throttling orifice and guiding part, which makes the flow of the medium not smooth, or the filler is too tight in the repair of the regulating valve, which results in the increase of the friction force, and then causes the phenomenon that the small signal does not act and the big signal moves too far.
        處理建議:可迅速開、關副線或調節閥,讓臟物從副線或球閥處被介質沖跑。另一辦法用管鉗夾緊閥桿,在外加信號壓力情況下,正反用力旋動閥桿,讓閥芯閃過卡處。若不能則增加氣源壓力增加驅動功率反復上下移動幾次,即可解決問題。如若仍不動作,則需解體處理。
         Handling advice: Quickly open or close the secondary line or regulating valve to make the dirt run from the secondary line or the ball valve by the medium. Another method is to clamp the valve stem with a pipe wrench. When the signal pressure is applied, the valve stem is forced to rotate forward and backward so that the spool flashes past the jamming part. If not, increase the air pressure and increase the drive power by moving it up and down several times, and through this, can solve the problem. If it still does not work, it needs to be dismantled.
        2、泄漏
        2. Leakage
        2.1閥內漏:閥桿長短不適。閥桿太長,閥桿向上的(或向下)的距離不夠,造成閥芯和蝶閥閥座之間有空隙,不能充分接觸,導致關不嚴而內漏。閥桿太短,導致閥芯和閥座之間有空隙,不能充分接觸,導致關不嚴而內漏。
        2.1 Valve inner leakage: The length of the stem is not suitable. The valve stem is too long, and the upward (or downward) distance of the valve stem is not enough, resulting in a gap between the valve plug and the butterfly valve seat, which cannot be fully contacted, resulting in loose shut-off and internal leakage. The valve stem is too short, resulting in a gap between the valve plug and the valve seat that cannot be fully contacted, resulting in loose shut-off and internal leakage. 
        處理建議:應縮短(或延長)調節閥閥桿使調節閥長度合適,使其不再內漏。
         Handling advice: The valve stem should be shortened (or lengthened), make the length of the regulating valve is appropriate so that it is no longer with inner leakage.
        2.2填料泄漏:填料裝入填料函以后,經壓蓋對其施加軸向壓力。由于填料的塑性,使其產生徑向力,并與閥桿緊密接觸,但這種接觸是并不是非常均勻的。有些部位接觸的松,有些部位接觸的緊,甚至有些部位沒有接觸上。閘閥在使用過程中,閥桿同填料之間存在著相對運動,這個運動叫軸向運動。在使用過程中,隨著高溫、高壓和滲透性強的流體介質的影響,調節閥填料函也是發生泄漏現象較多的部位。造成填料泄漏的主要原因是界面泄漏,對于紡織填料還會出現滲漏(壓力介質沿著填料纖維之間的微小縫隙向外泄漏)。閥桿與填料間的界面泄漏是由于填料接觸壓力的逐漸衰減,填料自身老化等原因引起的,這時壓力介質就會沿著填料與閥桿之間的接觸間隙向外泄漏。
        2.2 Packing Leakage: After the packing is packed into the stuffing box, axial pressure is applied to the plug by the cover. Due to the plasticity of the packing, it generates a radial force and is in close contact with the valve stem, but this contact is not very uniform. Some parts of the loose contact, some parts of the contact tight, and even some parts of no contact. During the use of the gate valve, there is relative motion between the valve stem and the packing, this movement is called axial movement. In the process of use, with the influence of high temperature, high pressure and fluid medium with strong permeability, the valve packing box is also the site where more leakage occurs. The main reason of the leakage of the filler is the interface leakage, and leakage occurs to the textile filler (the pressure medium leaks outward along the tiny gap between the filler fibers). The interface leakage between the valve stem and the packing is caused by the gradual attenuation of the packing contact pressure and the aging of the packing itself. At this time, the pressure medium leaks outward along the contact gap between the packing and the valve stem. 
        處理建議:為使填料裝入方便,在填料函頂端倒角,在填料函底部放置耐沖蝕的間隙較小的金屬保護環(截止閥與填料的接觸面不能為斜面),以防止填料被介質壓力推出。填料函各部與填料接觸部分的金屬表面要精加工,以提高表面光潔度,減少填料磨損。填料選用柔性石墨,因其具有氣密性好,摩擦力小,長期使用后變化小,磨損的燒損小,維修容易,壓蓋螺栓重新擰緊后摩擦力不發生變化,耐壓性和耐熱性良好,不受內部介質的侵蝕,與閥桿和填料函內部接觸的金屬不發生點蝕或腐蝕。這樣,有效地保護了減壓閥閥桿填料函的密封,保證了填料的密封的可靠性和長期性。
         Handling advice: In order to make packing convenient, chamfering at the top of the stuffing box. Place a metal protection ring (the contact surface between the cut-off valve and the packing can’t be inclined) with less erosion resistance at the bottom of the stuffing box to prevent the packing from being pushed out by the medium pressure. The metal surface of each part of the stuffing box and the contact part of the packing should be fined to improve the surface finish and reduce the wear of the packing. Filler is made of flexible graphite, because of its good airtightness, low friction, small changes after long-term use, small wear loss, easy maintenance, no change in friction force after the retightening of the cap bolt, good pressure resistance and heat resistance, no erosion of the internal medium, no corrosive pitting or corrosion of the metal in contact with the stem and stuffing box. In this way, the seal of the pressure-relief valve stem packing box effectively protected, the reliability and long-term stability of the packing seal is ensured.
        2.3閥芯、閥座變形泄漏:芯、閥座泄漏的主要原因是由于調節閥生產過程中的鑄造或鍛造缺陷可導致腐蝕的加強。而腐蝕介質的通過,流體介質的沖刷也可造成調節閥的泄漏。腐蝕主要以侵蝕或氣蝕的形式存在。當腐蝕性介質在通過調節閥時,便會產生對閥芯、閥座材料的侵蝕和沖擊使船用閥門閥芯、閥座成橢圓形或其他形狀,隨著時間的推移,導致閥芯、閥座不配套,存在間隙,關不嚴發生泄漏。
         2.3 The deformation leakage of spool and valve seat: spool, valve seat leakage is mainly due to the production of the valve in the process of casting or forging defects have resulted in the reinforcement of the corrosion. The passage of corrosive medium, the flushing of the fluid medium can also cause leakage of the regulating valve. Corrosion mainly occurs in the form of erosion or cavitation. When the corrosive medium passes through the regulating valve, it will produce the erosion and impact on the valve core and the seat material, so that the valve plug and the valve seat of the marine valve are formed into an elliptical shape or other shapes. Over time, the valve core and seat are not matched, with gap and resulting in loose shut-off and leakage
        處理建議:關鍵把好閥芯、閥座的材質的選型關、質量關。選擇耐腐蝕材料,對麻點、沙眼等缺陷的產品堅決剔除。若閥芯、閥座變形不太嚴重,可經過細砂紙研磨,消除痕跡,提高密封光潔度,以提高密封性能。若損壞嚴重,則應重新更換新閥。
         Handling suggestions: The key is to select suitable material and quality of the valve core and valve seat. Choose corrosion-resistant materials and strongly reject defective products such as pits and trachoma. If the valve core and the valve seat are not deformed seriously, they can be ground with fine sandpaper to eliminate the marks and improve the sealing finish to improve the sealing performance. If the damage is serious, the new valve should be replaced.
        3、振蕩
         3. Oscillations
        調節閥的彈簧剛度不足,調節閥輸出信號不穩定而急劇襯氟襯膠閥變動易引起調節閥振蕩。還有說選閥的頻率與系統頻率相同或管道、基座劇烈振動,使調節閥隨之振動。選型不當,調節閥工作在小開度存在著急劇的流阻、流速、壓力的變化,當超過閥剛度,穩定性變差,嚴重時產生振蕩。
         The spring stiffness of the regulating valve is insufficient, the output signal of the regulating valve is unstable, and the sudden change of the fluorine-lined rubber valve can easily cause oscillation of the regulating valve. It is also said that the frequency of the selection valve is the same as the frequency of the system or the severe vibration of the pipe and base makes the valve vibrate accordingly. Improper selection, there is a sharp flow resistance, flow velocity, and pressure changes in the valve operating at a small opening. When the valve stiffness is exceeded, the stability becomes worse, and the oscillation occurs when it is severe.
        處理建議:由于產生振蕩的原因是多方面的,因此具體問題具體分析。對振動輕微的振動,可增加剛度來消除。陶瓷閥如選用大剛度彈簧,改用活塞執行結構。管道、基座劇烈震動通過增加支撐消除振動干擾;選閥的頻率與系統頻率相同,則更換不同結構的閥;工作在小開度造成的振蕩,則是選型不當流通能力C值選大,必須重新選型流通能力C值較小的或采用分程控制或子母閥以克服調節閥工作在小開度。
         Handling advice: due to the causes of the oscillations are various, specific problems should with specific analysis. For slight vibration, stiffness can be increased to eliminate it. Ceramic valves use large stiffness springs, and with piston actuating structure. The violent vibration of pipelines and bases eliminates the vibration interference by increasing the support; if the frequency of the valve selection is the same as the system frequency, the valves of different structures are replaced; if the oscillation caused by operating in the small opening, it is due to the improper selection of flow capacity of relatively large C value, flow capacity must be reselect the small C value or use split control or mother valve to overcome the operation of regulating valve in the small opening.

        為了更好的避免電動調節閥或電動執行器門在現場管線上出現故障,出廠前,應該盡可能的在檢測線上全面檢測,一般檢測的遵循事例如下:
         In order to better avoid failure of the electric regulating valve or electric actuators in the field pipeline, before leaving the factory, it should be fully tested as far as possible on the test line. The following are examples of general inspections:
        (1)一般情況下,閥門不作強度試驗,但修補過后閥體和閥蓋或腐蝕損傷的閥體和閥蓋應作強度試驗。對于安全閥,其定壓和回座壓力及其他試驗應符合視鏡視盅閥其說明書和有關規程的規定。
         (1) Under normal circumstances, the valve shall not be subjected to strength tests. However, after the repair, the valve body and valve cover or corroded valve body and valve cover shall have a strength test. For safety valves, their constant pressure, return pressure and other tests shall comply with the specifications and regulations of the visual mirror cup valve.
        (2)閥門安裝之彰應作強度和密封性試驗。低壓閥門抽查20%,如不合格應100%的檢查;中、高壓閥門應100%的檢查。
         (2) Strength and tightness tests shall be made prior to valve installation. Low-pressure valve checks 20%, if unqualified, all should be in inspection; medium and high pressure valves should be inspection.
        (3)試驗時,閥門安裝位置應在容易進行檢查的方向。
         (3) During the test, the valve installation position should be in a place where it is easy to check.
        (4)焊接連接形式的閥門,用肓板試壓不行時可采用錐形密封或O型圈密封進行試壓。
         (4) Valves in the form of welded joints may be tested by taper seals or O-shaped sealing ring when the pressure test is not suitable with a sampan plate.
        (5)液壓試驗時就將閥門空氣盡量排除。
         (5) The valve air should be eliminated as much as possible during the hydraulic test.
        (6)試驗時壓衛生級閥門力要逐漸增高,不允許急劇、突然地增壓。
         (6) The pressure of the sanitary valve in the test should be gradually increased, and it is not allowed to pressurize abruptly and suddenly.
        (7)強度試驗和密封性式驗持續時間一般為2-3min,重要的和特殊的閥門應持續5min。小口徑閥門試驗時間可相應短一些,大口徑閥門試驗時間可相應長一些。在試驗過程中,如有疑問可延長試驗時間。強度試驗時,不允許閥體和閥蓋出現冒汗或滲漏現象。密封性試驗,轉子泵一般閥門只進行一次,安全閥、高壓閥等生要閥門需進行兩次。試驗時,對低壓、大口徑的不重要閥門以及有規定允許滲漏的閥門,允許有微量的滲漏現象;由于電站用閥、化工閥門、冶金閥門、高溫高壓閥門以及其他閥門要求各異,對電磁閥滲漏要求應按有關規定執行。
        (7) The duration of strength test and sealability test is generally 2-3 minutes, and important and special valves should be tested last 5 minutes. Small-diameter valve test time can be correspondingly shorter, large-diameter valve test time can be longer. During the test, the test time can be extended if in doubt. In the strength test, the valve body and valve cover are not allowed to sweat or leak. In the sealing test, the general valve of the rotor pump only be tested once, safety valve, high pressure valve and other important valves need to be tested twice. During the test, for the low-pressure, large-diameter, non-essential valves and the valves that are allowed to leak, a slight leakage is allowed; due to the requirements of power station valves, chemical valves, metallurgical valves, high-temperature and high-pressure valves and other valves are various. Solenoid valve leakage requirements should be implemented in accordance with relevant regulations.

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