In the modern industrial automation control system, the regulating valve is an indispensable link. Therefore, the normal operation of the regulating valve is related to the guarantee of the quality and output of the industrial products. Therefore, the instrumentation in the factory must master the basic regulating valve. Market and daily life problems and solutions, the following Xinke regulating valve manufacturers take you to understand, let's take a look ~~
First, the development direction of the regulating valve:
The development direction of the regulating valve is mainly intelligent, standardized, refined, rotated and safe.
1. Intelligentization and standardization: The intelligentization and standardization of regulating valves have been mentioned on the agenda, and the intelligentization mainly uses intelligent valve positioners. The intelligent valve positioner has self-diagnosis and remote communication functions, which makes the management of the regulating valve convenient and easy to diagnose. The intelligent valve positioner can not only easily change the flow characteristics of the regulating valve, but also provide the control quality of the control system. Therefore, the requirements for the flow characteristics of the regulating valve can be simplified and standardized. In addition, the intelligent valve positioner is based on the HART communication protocol, enabling control functions to be implemented at the field level, distracting the hazard and making the control more timely and faster. The main function of the regulating valve is that the various components are modularized, so that when the regulating valve needs to be repaired and replaced, it is only necessary to replace some of the fittings, which greatly saves maintenance cost and time.
2. Minimalization: The miniaturization is mainly embodied in: using a small and small actuator to reduce the volume and weight of the valve; changing the flow path structure to change the linear displacement to an angular displacement.
3. Rotation: Since rotary control valves such as ball valves and butterfly valves have the advantages of small relative volume, small flow resistance, large adjustable ratio, good sealing performance and large circulation capacity, the proportion of rotary valves in new varieties of regulating valves In the increase, especially in large-diameter pipelines, ball valves and butterfly valves are commonly used for adjustment.
4. Safety: The safety of the instrument control system has been paid attention to by all aspects. The safety instrument system (SIS) has higher and higher requirements for the regulating valve. The main performance is as follows: the requirements for the diagnosis and treatment of the regulating valve fault information are improved; For regulating valves used in emergency parking systems or safety interlock systems, timely, reliable and safe action requirements are required to ensure that these regulating valves are responsive and accurate; for regulating valves used in hazardous locations, the certification procedure should be simplified; The safety of other on-site instruments is similar. For the safety of the regulating valve, flameproof technology, fireproof technology, increased safety technology, intrinsic safety technology, non-sparking technology, etc. can be used.
5, energy saving: reducing energy consumption, improving energy efficiency is a development direction of the regulating valve, the main way: the use of low pressure drop ratio regulating valve; using self-operated regulating valve; using electric regulating valve; using piezoelectric locator; The valve core structure with balanced structure reduces the thrust or torque of the actuator; it is replaced by frequency conversion technology.
6. Protecting the environment: Environmental pollution has become a public hazard. The pollution of the regulating valve to the environment mainly includes the noise and leakage of the regulating valve, among which the noise pollution is more serious.
Second, the importance of the regulating valve:
The regulating valve is used to regulate the flow of the operating variable and is therefore referred to as a regulating valve. From the perspective of the control system as a whole, if a control system is well controlled, it must be realized by adjusting the valve. The regulating valve becomes very important for the following reasons.
1. The regulating valve is a throttling device, which belongs to the moving component. Compared with the detecting component, the transmitter and the controller, in the control process, the regulating valve needs to constantly change the flow area of ​​the throttle member, so that the manipulated variable changes to adapt to the load. Change or change in operating conditions. Therefore, higher requirements are placed on the sealing, pressure resistance, corrosion, etc. of the regulating valve valve assembly. For example, the seal will increase the friction of the regulating valve, and the dead zone of the regulating valve will increase, resulting in poor control quality of the control system.
2. The moving parts of the regulating valve are the main cause of running, running, dripping and leaking. It not only causes waste of resources or materials, but also pollutes the environment and causes accidents.
The contact medium of the regulating valve material may be different from the contact medium of the detecting element, so higher requirements are imposed on the corrosion resistance, strength and rigidity of the regulating valve.
3. The throttling of the regulating valve causes the energy to be consumed inside the valve. Therefore, it is necessary to rationally select and balance between reducing energy consumption, reducing the pressure loss of the regulating valve, and ensuring better control quality.
4. The regulating valve also throttles the fluid and also causes noise. For example, when the outlet pressure of the regulating valve is lower than the vapor pressure of the liquid, it causes flashing; when the pressure downstream of the regulating valve is higher than the vapor pressure of the liquid, causing cavitation . The noise caused by the regulating valve is related to the design of the regulating valve flow path, the operating pressure, and the characteristics of the controlled medium. Therefore, reducing noise, reducing pressure loss, etc. puts higher demands on the regulating valve.
5. The adaptability of the regulating valve is strong. It is installed in various production processes. The operating conditions such as high temperature, low temperature, high pressure, large flow rate, and small flow rate require various functions of the regulating valve. The regulating valve can adapt to the requirements of different applications.
6. The detection components, transmitters, controllers, etc. are developing fast, and the human and material resources invested are relatively high. Relatively speaking, it is generally considered that the structure of the regulating valve is simple, so the manpower and material resources for research and development of the regulating valve input are relatively insufficient.
The above is to introduce the development direction and importance of the regulating valve. After understanding these, there are many dealers who want to do the regulating valve. I hope to help you. Xinke Valve is a professional pneumatic regulating valve, steam pressure reducing valve and self-regulating. Valves, temperature control valves and other products, the company has always adhered to the "integrity management, the pursuit of first-class" purposes, with a large number of engineering applications in petrochemical, urban heating, heating pipe network and various industries, can provide professional and reliable for the majority of users The fast and flexible full-process engineering service enables users to relieve their worries and optimize their return on investment. Xiaobian also recommended for everyone that "the commonly used methods in the daily use of regulating valves" can be understood in many ways.
Third, the maintenance method commonly used in the use of regulating valves:
The regulating valve is divided into an electric regulating valve and a pneumatic regulating valve, and a few occasions also have a hydraulic regulating valve. There are two types of regulator valve repairs:
1. It is preventive maintenance, mainly refers to the preventive maintenance measures taken in order to ensure the reliable operation of the regulating valve, in the absence of faults, including a series of preventive measures taken by the regulating valve when it is installed and used in the field.
2. It is faulty maintenance, that is, a series of maintenance work carried out when the regulating valve can not meet the operation requirements under the fault condition. Under normal circumstances, it is completed in the production workshop, and in special cases, it may be directly repaired on the pipeline.
1. Preventive maintenance: Preventive maintenance is planned maintenance before the failure of the regulating valve. It can be understood as routine maintenance, usually including the following tasks.
1.1 Elimination of stress; pipelines may generate various forces due to improper combination or installation, such as thermal stress generated by high temperature medium, stress caused by unbalanced tightening force during installation, some caused by artificial collision with regulating valve and its pipeline Stress, etc. These stresses can easily affect the performance of the regulating valve on the regulating valve and its pipeline. In severe cases, it will affect the regulating valve system itself, causing the stem and the guide to deform and not centered with the valve seat; for the split valve The body's regulating valve may cause the valve body flange to disengage; the stress may also cause the valve seat to leak. Therefore, it is necessary to ensure that stress is avoided or eliminated at any time, and the stress is directed away from the regulating valve.
1.2 Check the support; the optimal position for installing the regulating valve is to make the stroke direction of the valve stem and the actuator above the valve body in a vertical plane. If the regulator valve must be installed in a position where the valve stem moves horizontally or if the direction of movement of the valve stem is at an angle to the horizontal plane, the actuator should be supported so that the various components of the regulator valve are in a natural state. If the support is not added or the support is improperly installed, the valve stem and the valve seat may be distracted, which may lead to the difference or the leakage of the packing. Even if the regulating valve has fixing and supporting measures, it must be checked regularly. Check it in ~3 months.
1.3 Clear or annoy the foreign matter to enter. Always check the connection of the regulating valve to the pipeline for rust, welding slag, dirt, etc., and promptly remove it after discovery. If it is easy to accumulate foreign matter in the regulating valve and the pipe, it is necessary to install a simple filtering device on the side of the regulating valve. Where it is easy to penetrate hard materials in the process medium, it is necessary to install a permanent filter device. Because the regulating valve is closed, a small piece of rust or welding slag is enough to damage the well-polished sealing surface, and these dirt also cause wear on the regulating valve spool and the valve seat, affecting its normal operation.
1.4 Regularly check the gas source and power supply; the gas source is one of the key energy sources for driving the regulating valve. Although the membrane chamber that drives the regulating valve does not consume air, if the gas source system contains impurities such as moisture and oil, the valve positioner, the relay, and the like are blocked and malfunction. Therefore, the gas source and power source must be inspected regularly to ensure that the gas source is clean and dry, and the power supply is reliable.
1.5 Regular maintenance and refueling; filling and oiling need to be re-adjusted after short-term use. In the case of dust, the packing box and the guiding part should be protected by a plastic sleeve or a rubber sleeve around the valve stem. When there is corrosive gas or liquid droplets, special protective measures should be adopted. Generally, the control valve is wrapped with an anti-corrosion bag, but Note that it does not affect its operation. In the case of fire resistance requirements, special refractory coatings, fireproof bags, etc. may be used. The material of the fireproof bag contains multiple layers of ceramic fibers or glass fibers.
1.6 Transportation and storage; after assembling and painting the control valve and attaching the actuator, handwheel, positioner and other accessories as required, in order to prevent foreign matter from entering the regulating valve, all air ports connecting the regulating valve should be blocked. Blue is equipped with a protective cover, pay attention to the various connection parts, such as the position of the valve positioner intake pipe and the execution interface. Any protruding accessories such as oilers and potentiometers that are easily damaged should be removed from the joint, packaged separately and transported together with the regulator. The adjustment valve is fixed by a special bracket to prevent looseness and the overall vertical position or horizontal position. If transported remotely, it is best to ship in a solid wooden case. When storing the regulating valve, do not support the regulating valve in sensitive parts such as valve positioners, valve stems, etc. Environmental conditions for transportation and storage should meet the requirements of the product specification. It is best not to carry out other work in the storage area. When it is unavoidable, care must be taken not to touch the regulating valve. The site should also be protected from harsh conditions such as sand, dust, rain, etc. If there is no suitable place, the regulator valve must be placed in a moisture-proof bag or placed in a container before storage.
1.7 Inspection of safe operation; check valves and related accessories used in explosive hazardous areas should be checked for safe operation, for example, whether the sealing cover is tightened, the operation of the safety barrier, the power supply, etc., to ensure that the regulating valve and related accessories can safe operation.
2, faulty maintenance:
If the regulating valve cannot be operated or the operating requirements cannot be met, it indicates that there is a fault and the fault must be repaired. In the case where the cause of the failure cannot be confirmed, the following steps can generally be performed.
2.1 Cleaning; After removing the faulty regulating valve from the pipeline, the first step of the repair is to thoroughly clean the regulating valve. The regulating valve is easily contaminated by the process fluid. If the process medium is corrosive, explosive, or radioactive, it is harmful to the human body, and the parts soaked by the process must be cleaned by special methods. The cleaning method varies with the medium properties of the process. Under normal circumstances, as long as water or steam can be blown, for some pollution, such as alkaline medium, pickling method, heavy metal pollution should be treated at high temperature and long time. Avoid repeated contamination during cleaning and do so in a safe place. All cleaning tool containers, heating equipment, steam hoses, washing equipment, etc. must be prepared in advance.
2.2 Disassemble the regulating valve; when disassembling the regulating valve, indicate the connection position of the actuator corresponding to the valve body, separate the actuator from the upper bonnet, separate the upper bonnet cover from the valve body, and disassemble the upper bonnet and stuffing box components. After that, the valve core, valve stem and other components can be removed from the valve body. All disassembled parts and components must be carefully inspected to determine the need to repair and replace parts. Usually, after the disassembly of the regulating valve, pay attention to the following parts during the inspection:
1) The inner wall of the valve. Check its pressure and corrosion resistance;
2) Seat. Due to the infiltration of the medium, the threaded surface of the fixed valve seat is susceptible to corrosion and the valve seat is loose. For high pressure applications, the corrosion or damage of the sealing surface of the valve seat should also be checked. Of course, in some structures, the valve seat and the valve body are not Threaded connections are used, but the seals must be inspected;
3) Spool. Carefully check whether the various parts of the valve plug are corroded or worn, especially in the case of high pressure difference, the valve core wear is more serious, and the valve stem should also check whether there is a similar situation, and whether the connection with the valve core is loose;
4) Seal packing and gasket. Check the seal packing and gasket for aging, cracking, etc., and whether the mating surface is intact.
2.3 Disassemble the actuator; after disassembling the actuator, carefully inspect the bracket, diaphragm, spring, push rod and threaded joints, etc., where the bracket is a stressed member and cannot have cracks; the diaphragm is a key component and cannot be damaged or aged; Springs must not have cracks. For multiple spring actuators, as long as one of the springs is damaged, the performance of the entire actuator will be severely affected. Regardless of the part, once it is corroded or rusted, it is best to replace it with a new part.
2.4 Reassembly; reassemble after all parts and components have been repaired. During the reassembly process, pay attention to the appropriate gaskets and bolted joints, accurately centering and evenly tightening to prevent flange leakage. The torsion load of a bolt or stud is related to its size and is not allowed to be tightened too tightly. The type, quantity and installation method of the filler directly affect the sealing performance, and can not be taken lightly during assembly. After reassembling the actuator, apply appropriate lubricant to each friction zone, including stems and guides, actuator stems and guides, bearings, drive components, adjustment nuts, and so on.
2.5 test; after reassembly, the regulating valve must be tested, such as basic performance test, air tightness test, leakage test, etc., after passing the test, it can be sent to the site for installation.
3. Conclusion; faulty maintenance, also known as passive maintenance, is a maintenance method that occurs when the regulating valve fails. It is repaired due to equipment failure, which often causes the production process to stop. In serious cases, equipment damage or personnel may occur. Casualties, etc. Faulty repairs are undesirable in the production process. Preventive maintenance is a preventive maintenance method for adjusting the valve on time according to past operating experience, in the process of installation and use, in the case that the regulating valve has not failed, its purpose is to prevent it from happening. People usually make corresponding fault prevention measures according to the different operating conditions of the regulating valve. If the fault does not occur, the repair can be carried out, which can greatly reduce the probability of the fault occurring. In the practical application of the regulating valve, preventive maintenance and faulty maintenance are usually combined. The former is the main one and the latter is used to maximize the effective service life of the regulating valve. Only in this way can the utilization efficiency of the regulating valve be improved and reduced. The system failure rate, the improvement of the production efficiency and economic efficiency of the process technology and the adjustment quality of the energy system ensure the long-term, safe and efficient operation of the production equipment.
Fourth, the installation method of the regulating valve:
Electric regulating valves and pneumatic regulating valves are precision instruments. Even the best things can not be used correctly if they are not installed according to the specified requirements. Especially for new pipes and new valves, many problems will arise during transportation and installation. The correct installation method can ensure the normal operation of the regulating valve, which is also crucial for the later maintenance, maintenance and use.
1. In the initial stage of commissioning and overhauling of the newly installed regulating valve, it is necessary to take measures to isolate or remove the process piping during the purge to prevent the medium from circulating due to clogging of the welding slag, rust, etc. in the pipeline. Smooth, or the valve is too tight in the overhaul of the regulating valve, causing the friction to increase, resulting in the phenomenon that the small signal does not move and the large signal moves too far.
2. When installing the pneumatic regulating valve, pay attention to the air opening and air closing of the regulating valve to prevent the valve from leaking due to the discomfort of the valve stem length.
3. In order to prevent cavitation, the following points should be noted during the original selection and installation:
1) Install the regulating valve as far as possible at the lowest position of the system, so that the inlet pressure and outlet pressure of the regulating valve can be relatively increased;
2) Install a shut-off valve or orifice plate upstream or downstream of the regulating valve to change the original installation pressure drop characteristics of the regulating valve;
3) Special anti-cavitation internals can also effectively prevent flashing or cavitation, which can change the flow rate of the fluid in the regulating valve, thereby increasing the internal pressure;
4) Try to use a harder material control valve, because in the case of cavitation, for such a regulating valve, it has certain anti-erosion performance and wear resistance, and can make cavitation exist under certain conditions without damage adjustment. The inner part of the valve, on the contrary, for the soft material regulating valve, when the cavitation occurs, the inner part of the regulating valve will wear quickly.
4. The regulating valve should generally be installed upright. If it needs to be tilted, it should be supported.
5. The flow direction of the medium must be consistent with the arrow of the valve body.
6. The installation position of the regulating valve should be easy to observe, operate and maintain.
7. The signal tube of the actuator should have sufficient expansion allowance and should not interfere with the action of the actuator.
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