How to solve the problem of poor performance of co

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How to solve the problem of poor performance of control valve

I. selection of control valve:

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at present, the control valves commonly used in engineering are mainly solenoid valves and electric valves. However, they all have defects in use, such as the solenoid valve is easy to be blocked by foreign matters, the water resistance is large, and it must be maintained by special personnel for a long time; Although the electric valve has no water resistance, it needs necessary control circuit, so the waterproof steam erosion affects the service life, which is also the main problem that puzzles the promotion

second, how to solve the problem of poor performance of control valve

whether it is solenoid valve or electric valve, scale will not only cause valve leakage, but even affect the normal operation of the valve when it is serious. Therefore, how to eliminate the impact of scale has become a common concern in the industry

the process of control valve involves too much scope, so I can't make it clear to you here one by one. I have to check the information myself about this aspect. However, due to the poor performance of the control valve caused by the different design of the actuator and the use of filling materials, its law can be summarized:

1. The existence of dead zone in the process will make the process variables 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 can occur

2, ① main factors affecting dead zone. Friction, drift, shaft torsion, dead zone of amplifier. Various control valves are not sensitive to friction. For example, rotary valves are very sensitive to friction caused by high seat load, so we should pay attention to this when using. However, for some seal types, a high seat load is necessary to obtain a closure class. Haha, in this way, the design of this valve is very poor, and it is easy to cause a large dead zone, which has an obvious and decisive impact on the process deviation

the more the policy is woven, the more dense it is

② wear and tear. It is inevitable for the valve to be worn during normal use, but the wear of the lubricating layer is the most severe. According to our experiments, the lubricating rotary valve has only undergone hundreds of cycles, and the lubricating layer can be almost used with a brush (exaggeration, otherwise it is very depressing to write an article). In addition, the load caused by pressure will also lead to the wear of the sealing layer as the replacement of hydrofluorocarbons, which are the main factors leading to the increase of friction. What happened? Is to give the performance of the control valve to destruction

③ the friction of packing is the main source of friction of control valve. The friction caused by different packing is very different

④ different types of actuators also have a fundamental impact on friction. Generally speaking, spring diaphragm actuators are better than piston actuators

3. Design of positioner

from the initial thinking of design, the design of actuator and positioner must be considered together. How to design a good locator? From its important characteristics, it must be a high gain device. Its gain is composed of two parts: static gain and dynamic gain. The way to improve the static gain is to design a preamplifier. For example, nozzle baffle device. So a friend wants to ask how to get dynamic gain? It is obtained through a power amplifier, which is a slide valve (general). Now someone has used the microprocessor to set the positioner. It seems that the valve will talk and tell us what's wrong in the future. At that time, it was easy to do maintenance. get down to business. At the same time, a high-performance constant hardness tester with high static and dynamic gain tests the hardness of products mainly to ensure that the produced product quality positioner can provide the best overall performance in reducing process deviation for any given valve component after two months of development

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