1, Introduction
Simply put, electric valve is to control the valve with electric actuator, so as to realize the opening and closing of the valve. It can be divided into two parts, the upper part is an electric actuator and the lower part is a valve.
Advantages: it has good effect on medium and large caliber gas in liquid and is not affected by climate. Not affected by compressed air pressure.
Disadvantages: high cost and bad wet environment.
2. Operating principles
Electric valve usually consists of electric actuator and valve. The electric valve is driven by electric energy, and the valve is driven by the electric actuator to realize the opening and closing of the valve. So as to achieve the purpose of switching pipeline media.
Solenoid valve is a kind of electric valve; The magnetic field generated by the electromagnetic coil is used to pull the valve core, thus changing the on-off of the valve body. When the coil is de-energized, the spool will retract under the pressure of the spring.
Step 3 use
Electric valve: It is used for analog adjustment of medium flow in liquid, gas and wind systems, and controlled by AO. In the control of large valves and wind power systems, electric valves can also be used for two-position switch control.
4. Method of operation
Preparation before operation
A. 1 read the operating instructions carefully before operating the valve.
2 Before operation, be sure to know the flow direction of gas, and pay attention to check the opening and closing signs of valves.
A.3 Check the appearance of the electric valve to see if it is wet; if it is wet, dry it; If other problems are found, they should be dealt with in time, and fault operation is not allowed.
A.4 For electric devices that have been stopped for more than 3 months, check the clutch before starting, and then check the insulation, steering and electrical wiring of the motor after confirming that the handle is in the manual position.
Matters needing attention in operation of electric valve
B. 1 Start, and confirm that the clutch handle is in the corresponding position.
B.2 If the electric valve is controlled in the control room, turn the transfer switch to a remote position, and then control the switch of the electric valve through the SCADA system.
B.3 For manual control, turn the change-over switch to the local position and operate the electric valve switch locally. When the electric valve is opened or closed, it will automatically stop working, and finally turn the operation switch to the middle position.
B.4 When operating the valve on site, the valve opening and closing instructions and the operation of the valve stem should be monitored, and the valve opening and closing degree should meet the requirements.
B.5 When the valve is fully closed by field operation, the electric valve should be stopped before the valve is closed in place, and the valve should be closed in place by inching.
B.6 After setting the stroke and torque controller, when the valve is completely opened or closed for the first time, the control of the stroke should be monitored. If the valve does not stop when it is switched to the position, it should be stopped manually immediately.
B.7 In the process of valve opening and closing, if the signal indication is wrong and the valve has abnormal noise, stop the machine in time for inspection.
B.8 After successful operation, the power supply of the electric valve should be turned off.
B.9 When operating multiple valves at the same time, pay attention to the operation sequence to meet the production process requirements.
B. 10 When opening a large-caliber valve with a bypass valve, if the pressure difference between the two ends is large, the bypass valve should be opened for pressure regulation first, and then the main valve should be opened: after the main valve is opened, the bypass valve should be closed immediately.
B. 1 1 When receiving and sending pigging balls (devices), the ball valves that they pass through must be fully opened.
B. 12 operating ball valves, gate valves, globe valves and butterfly valves can only be fully opened or closed, and adjustment is prohibited.
B13 gate valve, globe valve and flat valve shall rotate 1/2 ~ 1 turn when they are closed or opened to the top dead center or bottom dead center during operation.
5. Maintenance
Daily maintenance of electric valve
1, the electric valve should be stored in a dry and ventilated room, and both ends of the channel should be blocked.
2, long-term storage of electric valve should be regularly checked, remove dirt, and coated with antirust oil on the processing surface.
3, after installation, should be checked regularly, the main inspection items:
(1) The sealing surface is worn.
(2) The trapezoidal threads of the valve stem and the valve stem nut are worn.
(3) Whether the filler has expired, and replace it in time if it is damaged.
(4) After the electric valve is overhauled and assembled, the sealing performance test should be carried out.
Electric valves in operation, all kinds of valves should be complete and in good condition. Flange threads and bolts on the bracket are indispensable, and the threads should be intact, and no looseness is allowed. If the fastening nut on the handwheel is found to be loose, it should be tightened in time to avoid wearing the joint or losing the handwheel and nameplate. If the handwheel is lost, it is not allowed to be replaced with a wrench. It should be filled in time. Packing gland is not allowed to be skewed or without pre-tightening clearance. For electric valves that are easily polluted by pollutants such as rain, snow, dust and sand, the valve stem should be equipped with a protective cover. The scale on the electric valve should be complete, accurate and clear. The lead seal, cap and pneumatic accessories of electric valve shall be intact. Insulating sheath shall be free from dents and cracks.
It is not allowed to knock, stand or support heavy objects on the running electric valve door; In particular, nonmetallic electric valves and cast iron electric valves should be prohibited.
6, choose and buy
Valve electric device is an indispensable equipment to realize valve program control, automatic control and remote control, and its movement process can be controlled by stroke, torque or axial thrust. Because the working characteristics and utilization rate of valve electric device depend on the type of valve, the working specifications of the device and the position of the valve on the pipeline or equipment, it is very important to choose the valve electric device correctly to prevent overload (the working torque is higher than the control torque). Generally speaking, the correct selection of valve electric device is based on: operating torque: operating torque is the most important parameter for selecting valve electric device, and the output torque of electric device should be 1.2 ~ 1.5 times of the maximum operating torque of the valve.
Working thrust: there are two main engine structures of valve electric device: one is to directly output torque without thrust plate; The other is to configure a thrust disc, and the output torque is converted into output thrust through the valve stem nut in the thrust disc.
Number of revolutions of output shaft: The number of revolutions of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem and the number of threaded heads, and should be calculated as M=H/ZS (m is the total number of revolutions that the electric device should meet, h is the opening height of the valve, s is the pitch of the valve stem transmission, and z is the number of threaded heads of the valve stem).
Stem diameter: For a multi-turn open stem valve, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the exposed stem valve. For some rotary valves and hidden stem valves in multi-rotary valves, it is not necessary to pass the valve stem diameter, but the valve stem diameter and keyway size should be fully considered in the selection to make them work normally after assembly.
7. Installation precautions
The electric device of electric valve is one of the devices used to operate and connect the valve. The device is driven by electricity, and its movement process can be controlled by stroke, torque or axial thrust. Because the working characteristics and utilization rate of valve electric device depend on the type of valve, the working specifications of the device and the position of the valve on the pipeline or equipment. Therefore, master the correct choice of valve electric device; It is very important to consider preventing overload (working torque is higher than control torque).
The correct selection of electrical equipment should be based on
1. Operating torque: Operating torque is the most important parameter for selecting valve electric device. The output torque of the electric device shall be 1.2 ~ 1.5 times of the maximum operating torque of the valve.
2. Working thrust: There are two main structures of the valve electric device, one is that the thrust plate is not installed, and the torque is directly output at this time; The other is equipped with a thrust disc, at which time the output torque is converted into output thrust through the valve stem nut in the thrust disc.
3. Output shaft revolution: The revolution of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem and the number of screw heads, and is calculated as M=H/ZS (where m is the total revolution that the electric device should meet; H is the opening height of the valve, mm; S is the pitch of the valve stem transmission thread, mm; Z is the number of threaded heads of the valve stem. )
4. Stem diameter: For a multi-turn open stem valve, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the exposed stem valve. For some rotary valves and hidden stem valves in multi-rotary valves, it is not necessary to pass the valve stem diameter, but the valve stem diameter and keyway size should be fully considered in the selection to make them work normally after assembly.
5. Output speed: the valve is fast in opening and closing speed, and it is easy to produce water hammer. Therefore, the appropriate opening and closing speed should be selected according to different use conditions.
6. Installation and connection methods: The installation methods of electrical devices include vertical installation, horizontal installation and floor installation; Connection mode: thrust plate; The valve stem passes through (open-stem multi-rotary valve); Multiple rotations of hidden rods; Thrust-free disk; The valve stem does not pass; Partial rotary electric device is widely used, and it is an indispensable equipment to realize program control, automatic control and remote control of valves. It is mainly used for closed-circuit valves. But we can't ignore the special requirements of valve electric device-it must be able to limit torque or axial force. Usually, the valve electric device uses a coupling that limits torque.
When the specification of the electric device is determined, its control torque is also determined. When it runs within a predetermined time, the motor is generally not overloaded. However, it may be overloaded under the following circumstances:
1. The power supply voltage is low, and the required torque cannot be obtained, so that the motor stops running.
2. The torque limiting mechanism is wrongly set to be greater than the stopping torque, resulting in excessive torque and stopping the motor.
3. If it is used intermittently like inching, the generated heat will accumulate and exceed the allowable temperature of the motor.
4. For some reason, the circuit of the torque limiting mechanism fails, resulting in excessive torque.
5. The operating environment temperature is too high, which makes the heat capacity of the motor relatively lower.
The above are some reasons for overload. The motor overheating caused by these reasons should be considered in advance and measures should be taken to prevent overheating.
In the past, the methods to protect the motor were fuses, overcurrent relays, thermal relays, thermostats and so on. But these methods also have their own advantages and disadvantages. There is no absolutely reliable protection method for variable load equipment such as electrical equipment. Therefore, it is necessary to adopt a combination of various methods. However, it is difficult to put forward a unified method because of the different load conditions of electrical equipment. But in most cases, we can also find similarities.
The overload protection methods adopted can be summarized into two types.
1. Judge the increase or decrease of motor input current;
2. Judge that the motor itself is hot.
The above two methods, no matter which one, should consider the time margin given by the heat capacity of the motor. It is difficult to make it consistent with the heat capacity characteristics of the motor in a single way. Therefore, reliable action modes-combination and compound mode-should be selected according to overload reasons to realize comprehensive overload protection.
The motor of Rottok electrical equipment is embedded with a thermostat with the same insulation level in the winding. When the rated temperature is reached, the motor control loop will be cut off. The thermostat itself has a small heat capacity, and its time-limited characteristics are determined by the heat capacity characteristics of the motor, so this is a reliable method.
Basic protection methods of overload
1. Temperature controller is used for overload protection of motor in continuous operation or inching operation;
2. The thermal relay is used to prevent the motor from locking and rotating;
3. Use fuse or overcurrent relay for short circuit accident.
The correct selection of valve electric device is closely related to the prevention of overload and should be paid attention to.
Introduction of electric valve, 304 stainless steel valve and 32 1 stainless steel valve.
Introduction of Electric Valve 304 Stainless Steel Valve
The working distance of electric valve is larger than that of ordinary valve, and the opening and closing speed of electric valve is adjustable, with simple structure and convenient maintenance. The valve can be used to control the flow of various types of fluids, such as air, water, steam, corrosive media, mud, oil, liquid metal and radioactive media. In the process of action, due to the buffering characteristics of gas itself, it is not easy to be damaged by jamming, but there must be a gas source, and its control system is more complicated than that of electric valve. Generally, this valve should be installed horizontally in the pipeline.
1, Introduction
Simply put, electric valve is to control the valve with electric actuator, so as to realize the opening and closing of the valve. It can be divided into two parts, the upper part is an electric actuator and the lower part is a valve.
Advantages: it has good effect on medium and large caliber gas in liquid and is not affected by climate. Not affected by compressed air pressure.
Disadvantages: high cost and bad wet environment.
2. Operating principles
Electric valve usually consists of electric actuator and valve. The electric valve is driven by electric energy, and the valve is driven by the electric actuator to realize the opening and closing of the valve. So as to achieve the purpose of switching pipeline media.
Solenoid valve is a kind of electric valve; The magnetic field generated by the electromagnetic coil is used to pull the valve core, thus changing the on-off of the valve body. When the coil is de-energized, the spool will retract under the pressure of the spring.
Step 3 use
Electric valve: it is used for analog adjustment of medium flow in liquid, gas and wind systems, and is controlled by AO. In the control of large valves and wind power systems, electric valves can also be used for two-position switch control.
4. Method of operation
Preparation before operation
A. 1 read the operating instructions carefully before operating the valve.
2 Before operation, be sure to know the flow direction of gas, and pay attention to check the opening and closing signs of valves.
A.3 Check the appearance of the electric valve to see if it is wet; if it is wet, dry it; If other problems are found, they should be dealt with in time, and fault operation is not allowed.
A.4 For electric devices that have been stopped for more than 3 months, check the clutch before starting, and then check the insulation, steering and electrical wiring of the motor after confirming that the handle is in the manual position.
Matters needing attention in operation of electric valve
B. 1 Start, and confirm that the clutch handle is in the corresponding position.
B.2 If the electric valve is controlled in the control room, turn the transfer switch to a remote position, and then control the switch of the electric valve through the SCADA system.
B.3 For manual control, turn the change-over switch to the local position and operate the electric valve switch locally. When the electric valve is opened or closed, it will automatically stop working, and finally turn the operation switch to the middle position.
B.4 When operating the valve on site, the valve opening and closing instructions and the operation of the valve stem should be monitored, and the valve opening and closing degree should meet the requirements.
B.5 When the valve is fully closed by field operation, the electric valve should be stopped before the valve is closed in place, and the valve should be closed in place by inching.
B.6 After setting the stroke and torque controller, when the valve is completely opened or closed for the first time, the control of the stroke should be monitored. If the valve does not stop when it is switched to the position, it should be stopped manually immediately.
B.7 In the process of valve opening and closing, if the signal indication is wrong and the valve has abnormal noise, stop the machine in time for inspection.
B.8 After successful operation, the power supply of the electric valve should be turned off.
B.9 When operating multiple valves at the same time, pay attention to the operation sequence to meet the production process requirements.
B. 10 When opening a large-caliber valve with a bypass valve, if the pressure difference between the two ends is large, the bypass valve should be opened for pressure regulation first, and then the main valve should be opened: after the main valve is opened, the bypass valve should be closed immediately.
B. 1 1 When receiving and sending pigging balls (devices), the ball valves that they pass through must be fully opened.
B. 12 operating ball valves, gate valves, globe valves and butterfly valves can only be fully opened or closed, and adjustment is prohibited.
B13 gate valve, globe valve and flat valve shall rotate 1/2 ~ 1 turn when they are closed or opened to the top dead center or bottom dead center during operation.
5. Maintenance
Daily maintenance of electric valve
1, the electric valve should be stored in a dry and ventilated room, and both ends of the channel should be blocked.
2, long-term storage of electric valve should be regularly checked, remove dirt, and coated with antirust oil on the processing surface.
3, after installation, should be checked regularly, the main inspection items:
(1) The sealing surface is worn.
(2) The trapezoidal threads of the valve stem and the valve stem nut are worn.
(3) Whether the filler has expired, and replace it in time if it is damaged.
(4) After the electric valve is overhauled and assembled, the sealing performance test should be carried out.
Electric valves in operation, all kinds of valves should be complete and in good condition. Flange threads and bolts on the bracket are indispensable, and the threads should be intact, and no looseness is allowed. If the fastening nut on the handwheel is found to be loose, it should be tightened in time to avoid wearing the joint or losing the handwheel and nameplate. If the handwheel is lost, it is not allowed to be replaced with a wrench. It should be filled in time. Packing gland is not allowed to be skewed or without pre-tightening clearance. For electric valves that are easily polluted by pollutants such as rain, snow, dust and sand, the valve stem should be equipped with a protective cover. The scale on the electric valve should be complete, accurate and clear. The lead seal, cap and pneumatic accessories of electric valve shall be intact. Insulating sheath shall be free from dents and cracks.
It is not allowed to knock, stand or support heavy objects on the running electric valve door; In particular, nonmetallic electric valves and cast iron electric valves should be prohibited.
6, choose and buy
Valve electric device is an indispensable equipment to realize valve program control, automatic control and remote control, and its movement process can be controlled by stroke, torque or axial thrust. Because the working characteristics and utilization rate of valve electric device depend on the type of valve, the working specifications of the device and the position of the valve on the pipeline or equipment, it is very important to choose the valve electric device correctly to prevent overload (the working torque is higher than the control torque). Generally speaking, the correct selection of valve electric device is based on: operating torque: operating torque is the most important parameter for selecting valve electric device, and the output torque of electric device should be 1.2 ~ 1.5 times of the maximum operating torque of the valve.
Working thrust: there are two main engine structures of valve electric device: one is to directly output torque without thrust plate; The other is to configure a thrust disc, and the output torque is converted into output thrust through the valve stem nut in the thrust disc.
Number of revolutions of output shaft: The number of revolutions of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem and the number of threaded heads, and should be calculated as M=H/ZS (m is the total number of revolutions that the electric device should meet, h is the opening height of the valve, s is the pitch of the valve stem transmission, and z is the number of threaded heads of the valve stem).
Stem diameter: For a multi-turn open stem valve, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the exposed stem valve. For some rotary valves and hidden stem valves in multi-rotary valves, it is not necessary to pass the valve stem diameter, but the valve stem diameter and keyway size should be fully considered in the selection to make them work normally after assembly.
7. Installation precautions
The electric device of electric valve is one of the devices used to operate and connect the valve. The device is driven by electricity, and its movement process can be controlled by stroke, torque or axial thrust. Because the working characteristics and utilization rate of valve electric device depend on the type of valve, the working specifications of the device and the position of the valve on the pipeline or equipment. Therefore, master the correct choice of valve electric device; It is very important to consider preventing overload (working torque is higher than control torque).
The correct selection of electrical equipment should be based on
1. Operating torque: Operating torque is the most important parameter for selecting valve electric device. The output torque of the electric device shall be 1.2 ~ 1.5 times of the maximum operating torque of the valve.
2. Working thrust: There are two main structures of the valve electric device, one is that the thrust plate is not installed, and the torque is directly output at this time; The other is equipped with a thrust disc, at which time the output torque is converted into output thrust through the valve stem nut in the thrust disc.
3. Output shaft revolution: The revolution of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem and the number of screw heads, and is calculated as M=H/ZS (where m is the total revolution that the electric device should meet; H is the opening height of the valve, mm; S is the pitch of the valve stem transmission thread, mm; Z is the number of threaded heads of the valve stem. )
4. Stem diameter: For a multi-turn open stem valve, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the exposed stem valve. For some rotary valves and hidden stem valves in multi-rotary valves, it is not necessary to pass the valve stem diameter, but the valve stem diameter and keyway size should be fully considered in the selection to make them work normally after assembly.
5. Output speed: the valve is fast in opening and closing speed, and it is easy to produce water hammer. Therefore, the appropriate opening and closing speed should be selected according to different use conditions.
6. Installation and connection methods: The installation methods of electrical devices include vertical installation, horizontal installation and floor installation; Connection mode: thrust plate; The valve stem passes through (open-stem multi-rotary valve); Multiple rotations of hidden rods; Thrust-free disk; The valve stem does not pass; Partial rotary electric device is widely used, and it is an indispensable equipment to realize program control, automatic control and remote control of valves. It is mainly used for closed-circuit valves. But we can't ignore the special requirements of valve electric device-it must be able to limit torque or axial force. Usually, the valve electric device uses a coupling that limits torque.
When the specification of the electric device is determined, its control torque is also determined. When it runs within a predetermined time, the motor is generally not overloaded. However, it may be overloaded under the following circumstances:
1. The power supply voltage is low, and the required torque cannot be obtained, so that the motor stops running.
2. The torque limiting mechanism is wrongly set to be greater than the stopping torque, resulting in excessive torque and stopping the motor.
3. If it is used intermittently like inching, the generated heat will accumulate and exceed the allowable temperature of the motor.
4. For some reason, the circuit of the torque limiting mechanism fails, resulting in excessive torque.
5. The operating environment temperature is too high, which makes the heat capacity of the motor relatively lower.
The above are some reasons for overload. The motor overheating caused by these reasons should be considered in advance and measures should be taken to prevent overheating.
In the past, the methods to protect the motor were fuses, overcurrent relays, thermal relays, thermostats and so on. But these methods also have their own advantages and disadvantages. There is no absolutely reliable protection method for variable load equipment such as electrical equipment. Therefore, it is necessary to adopt a combination of various methods. However, it is difficult to put forward a unified method because of the different load conditions of electrical equipment. But in most cases, we can also find similarities.
The overload protection methods adopted can be summarized into two types.
1. Judge the increase or decrease of motor input current;
2. Judge that the motor itself is hot.
The above two methods, no matter which one, should consider the time margin given by the heat capacity of the motor. It is difficult to make it consistent with the heat capacity characteristics of the motor in a single way. Therefore, reliable action modes-combination and compound mode-should be selected according to overload reasons to realize comprehensive overload protection.
The motor of Rottok electrical equipment is embedded with a thermostat with the same insulation level in the winding. When the rated temperature is reached, the motor control loop will be cut off. The thermostat itself has a small heat capacity, and its time-limited characteristics are determined by the heat capacity characteristics of the motor, so this is a reliable method.
Basic protection methods of overload
1. Temperature controller is used for overload protection of motor in continuous operation or inching operation;
2. The thermal relay is used to prevent the motor from locking and rotating;
3. Use fuse or overcurrent relay for short circuit accident.
The correct selection of valve electric device is closely related to the prevention of overload and should be paid attention to.