Discussion on the application technology and fault maintenance of electro-hydraulic slide valves
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Currently, in China, there are three companies that produce electro-hydraulic actuators: Jiujiang Global, Jiujiang Instrument Factory, and Lanlian. Each of them is different, yet they share similar characteristics. All instrument technicians working in refineries are aware of the complex structure of electro-hydraulic actuators (sliding valves, plug valves, butterfly valves) and their importance to production. Every malfunction represents a challenge for us, and we welcome everyone to share their maintenance experiences here in order to improve together.
The failures we have encountered recently include issues with the power supply modules, which are supplied by external manufacturers. The prices of different power supply modules vary greatly, and it is difficult to assess their performance. The same is true for other accessories. Furthermore, there are many failures with the valve position sensors. Here, I would also like to ask everyone: how are the special valves and interlock safety signals connected in your systems? 1. Release oil pressure directly upon receiving signal from solenoid valve ； Or 2: connected to the control board contacts, with the opening degree ultimately adjusted by a servo valve (proportional valve).
Valve position transmitters come in LVDT types as well as those with a 4-20mA output; the self-protection signals are connected directly to the self-protection terminals on the terminal block, rather than directly to the solenoid valve
When I reach the third year, I’ll share some information on slide valves with everyone so we can study them together
Not many people are discussing it; it seems like everyone here are experts who disdain discussing such trivial matters O(∩_∩)O Haha~
Common faults: 1. Failure of the position sensor, resulting in inability to control the valve position； Replace the position sensor. 2. Power board failure, distorted display on the panel ； The filter capacitor on the power supply board has failed; replace it with a capacitor (35V/50V, 2200 microfarads)
I went to Lanlian for training before, and I also created some course materials on electro-hydraulic slide valve mechanisms which were posted on Haichuan. However, not many people responded. It’s not because they’re too superficial and I disdain discussing such trivial matters, but rather because few people have come into contact with them. It is generally used in the petrochemical industry, especially in catalytic cracking units, where there are many control and interlock points. If you understand the entire electro-hydraulic system for slide valves, your knowledge of instrumentation and automatic control will reach a new level. I can try to find the course materials I shared before; I hope they will be helpful to you. http://bbs.hcbbs.com/viewthread.php?tid=202684&page=1#pid880216
I think there are generally no issues with the slide valve circuit; the problems mainly occur in the oil circuit, and it is therefore necessary to ensure high quality and cleanliness of the oil. High-octane gasoline such as aviation fuel can be used on a regular basis to clean the oil circuit and the throttle components.
A flash file related to the servo valve has been uploaded; it’s available in the on-site instrument data sharing area, and those who are interested can take a look
Oil leaks are minor issues; the main problem is that some of the circuit boards inside are prone to damage, as well as the motors