At present, the control valves commonly used in engineering are mainly: solenoid valves and electric valves. However, they all have defects in use. For example, the solenoid valve is easily blocked by foreign matter, the water resistance is large, and it must be maintained by a long-term person. However, although the electric valve has no water resistance, it has the necessary control circuit, so the effect of waterproof steam erosion Service life is also a major problem that plagues promotion.
Locator design problem
From the initial thinking of the design, the actuator and locator design must be considered together. How to design a good locator? From his important characteristics, it must be a high gain device. The gain is made up of two parts: static gain and dynamic gain. The way to increase the static gain is to design a preamplifier. For example, the nozzle - the baffle device. So a friend asks how to get the dynamic gain? It is obtained through a power amplifier, which is a slide valve (generally). Now someone has used a microprocessor to set up the locator. It seems that the regulator will talk later and tell us where he is broken. At that time, it was simple to do maintenance. Closer to home. High performance positioners with high static and high dynamic gain simultaneously provide the best overall performance for any given regulator valve assembly with reduced process variation.
How to maximize the impact of scale on the use of regulating valves
Whether it is a solenoid valve or an electric valve, scale will not only cause leakage of the regulating valve, but even affect the normal operation of the regulating valve in serious cases. Therefore, how to eliminate the influence of scale is a common concern of the industry.
The scope of the control valve process is too wide, and you can't tell you clearly here. I hope that the content of this aspect is also personally checked the information. However, due to the poor performance of the control valve due to the difference between the design actuator and the use of filler materials, the regularity of the control valve can be summarized: 1. The presence of a dead zone during the process will cause the process variable to deviate from the original set point. Therefore, the output of the controller must be increased enough to overcome the dead zone, and only this corrective action will occur. 2, 1 The main factors affecting the dead zone. Friction, migration, valve shaft torsion, dead zone of the amplifier. Various control valves are not sensitive to friction. For example, rotary valves are very sensitive to friction caused by high seat loads, so note this when using them. However, for some seal types, a high seat load is necessary to achieve a shutdown rating. Haha, in this way, the design of this valve is very poor, and it is easy to cause a large dead zone. The influence of the process deviation is obvious and it is decisive. 2 wear. It is inevitable that the control valve will wear out during normal use, but the wear of the lubricating layer is the most powerful. According to our experiments, the lubrication rotary valve only passes through several hundred cycles, and the lubricating layer can be used almost as a brush (exaggeration) Point, or write an article is very depressed). In addition, the load caused by the pressure can also cause the wear of the sealing layer, which is the main factor that causes the friction to increase. The result is that the performance of the control valve is devastating! 3, the friction of the packing is the main source of the friction of the control valve, and the friction used is different. 4, the type of actuator also has a fundamental impact on friction, in general, the spring film actuator is better than the piston actuator.
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