The Siemens control valve is the most widely used version of the final control element. Other final control components include metering pumps, regulating baffles and louvered baffles (a variant of a butterfly valve), variable pitch fan blades, current regulating devices, and motor positioning devices other than valves. The history of Siemens regulating valves, whether it is modern industry or modern industry, Siemens regulating valve has played an irreplaceable role.
The Siemens control valve is the most widely used version of the final control element. Other final control components include metering pumps, regulating baffles and louvered baffles (a variant of a butterfly valve), variable pitch fan blades, current regulating devices, and motor positioning devices other than valves.
Despite the widespread use of Siemens regulators, the other units in the regulation system probably do not have as much maintenance as they do. In many systems, the regulating valve is subjected to operating conditions such as temperature, pressure, corrosion and contamination that are more severe than other components. However, when it controls the flow of the process fluid, it must operate satisfactorily and with minimal maintenance. the amount.
Siemens regulators act as variable resistance in the pipeline. It changes the turbulence of the process fluid or provides a pressure drop in laminar flow conditions caused by changing valve resistance or "friction." This pressure reduction process is often referred to as "throttle." For a gas, it is close to an isothermal adiabatic state, and the deviation depends on the non-ideality of the gas (Joule-Thomson effect). In the case of liquids, the pressure is consumed by turbulence or viscous friction, both of which convert the pressure into heat, resulting in a slight increase in temperature.
A common control loop consists of three main parts. The first part is the sensitive component, which is usually a transmitter. It is a device that can be used to measure the parameters of a process being adjusted, such as pressure, level or temperature. The output of the transmitter is sent to the regulating instrument, the regulator, which determines and measures the deviation between the setpoint or desired value and the actual value of the process parameter, and sends the correction signal one after the other to the final control element - adjustment valve. The valve changes the flow of the fluid so that the process parameters reach the desired value.
In the pneumatic adjustment system, the pneumatic signal output by the regulator can directly drive the spring-membrane actuator or the piston actuator to operate the valve. In this case, the energy required to determine the valve position is provided by compressed air, which should be dried in an outdoor unit to prevent freezing and should be purified and filtered.
When a pneumatic regulating valve and an electric regulator are used together, an electric one gas valve positioner or an electric one gas converter can be used. The air supply system for compressed air can be considered in the same way as a full pneumatic adjustment system.
In the terminology of regulation theory, the regulating valve has both static and dynamic characteristics, so it affects the success or failure of the entire control loop. The static characteristic or gain term is the flow characteristic of the valve, which depends on the size of the valve, the combination of the valve plug and the seat, the type of actuator, the positioner of the valve, the pressure before and after the valve, and the nature of the fluid. These are covered in more detail in Chapter 5.
The dynamic characteristics are determined by the actuator or the combination of the valve positioner and the actuator. For slower production processes, such as temperature control or level control, the dynamics of the valve are generally not a limiting factor in terms of controllability. For faster systems, such as flow control of liquids, the regulating valve may have significant hysteresis and must be considered in terms of controllability of the circuit. Generally only experts in the control system need to be concerned with the dynamic holding of the regulating valve. The formal considerations for applying the valve positioner, as discussed in Chapter 9, will meet the needs of most regulating valve devices.
The history of automatic regulators can be traced back to self-operated pressure regulators, which include a ball valve with a weight rod that balances the spool force to some degree of adjustment, and another early self-acting type. The form of pressure regulating 是 is a pressure balanced pressure regulating valve. The pressure of the process is connected by a line to the membrane chamber of the spring membrane regulator. Whether it is a pressure reducing valve, a post-valve pressure regulating valve or a differential pressure regulating valve, it can be manufactured from the change of this basic valve.
The advent of pneumatic transmitters and regulators has inevitably led to the application of pneumatic word valves. They are essentially pressure reducing valves or post-valve pressure regulating valves that use instrumented compressed air instead of process fluids. Many companies that produce pressure reducing valves have now developed into regulating valve manufacturers. The use of regulating valves continues to evolve in terms of quantity and complexity, and improvements in the valve bodies and accessories of many valves can be used to solve a wide variety of problems. The intent of this manual is to familiarize engineers with the entanglement and factors of regulating valves, and to help instrument engineers select the best valves, actuators and accessories for their applications.
The regulating valve belongs to the series of control valves. The main function is to adjust the pressure, flow, temperature and other parameters of the medium, which is the final control component in the process loop.
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The Siemens control valve is the most widely used version of the final control element. Other final control components include metering pumps, regulating baffles and louvered baffles (a variant of a butterfly valve), variable pitch fan blades, current regulating devices, and motor positioning devices other than valves.
Despite the widespread use of Siemens regulators, the other units in the regulation system probably do not have as much maintenance as they do. In many systems, the regulating valve is subjected to operating conditions such as temperature, pressure, corrosion and contamination that are more severe than other components. However, when it controls the flow of the process fluid, it must operate satisfactorily and with minimal maintenance. the amount.
Siemens regulators act as variable resistance in the pipeline. It changes the turbulence of the process fluid or provides a pressure drop in laminar flow conditions caused by changing valve resistance or "friction." This pressure reduction process is often referred to as "throttle." For a gas, it is close to an isothermal adiabatic state, and the deviation depends on the non-ideality of the gas (Joule-Thomson effect). In the case of liquids, the pressure is consumed by turbulence or viscous friction, both of which convert the pressure into heat, resulting in a slight increase in temperature.
A common control loop consists of three main parts. The first part is the sensitive component, which is usually a transmitter. It is a device that can be used to measure the parameters of a process being adjusted, such as pressure, level or temperature. The output of the transmitter is sent to the regulating instrument, the regulator, which determines and measures the deviation between the setpoint or desired value and the actual value of the process parameter, and sends the correction signal one after the other to the final control element - adjustment valve. The valve changes the flow of the fluid so that the process parameters reach the desired value.
In the pneumatic adjustment system, the pneumatic signal output by the regulator can directly drive the spring-membrane actuator or the piston actuator to operate the valve. In this case, the energy required to determine the valve position is provided by compressed air, which should be dried in an outdoor unit to prevent freezing and should be purified and filtered.
When a pneumatic regulating valve and an electric regulator are used together, an electric one gas valve positioner or an electric one gas converter can be used. The air supply system for compressed air can be considered in the same way as a full pneumatic adjustment system.
In the terminology of regulation theory, the regulating valve has both static and dynamic characteristics, so it affects the success or failure of the entire control loop. The static characteristic or gain term is the flow characteristic of the valve, which depends on the size of the valve, the combination of the valve plug and the seat, the type of actuator, the positioner of the valve, the pressure before and after the valve, and the nature of the fluid. These are covered in more detail in Chapter 5.
The dynamic characteristics are determined by the actuator or the combination of the valve positioner and the actuator. For slower production processes, such as temperature control or level control, the dynamics of the valve are generally not a limiting factor in terms of controllability. For faster systems, such as flow control of liquids, the regulating valve may have significant hysteresis and must be considered in terms of controllability of the circuit. Generally only experts in the control system need to be concerned with the dynamic holding of the regulating valve. The formal considerations for applying the valve positioner, as discussed in Chapter 9, will meet the needs of most regulating valve devices.
The history of automatic regulators can be traced back to self-operated pressure regulators, which include a ball valve with a weight rod that balances the spool force to some degree of adjustment, and another early self-acting type. The form of pressure regulating 是 is a pressure balanced pressure regulating valve. The pressure of the process is connected by a line to the membrane chamber of the spring membrane regulator. Whether it is a pressure reducing valve, a post-valve pressure regulating valve or a differential pressure regulating valve, it can be manufactured from the change of this basic valve.
The advent of pneumatic transmitters and regulators has inevitably led to the application of pneumatic word valves. They are essentially pressure reducing valves or post-valve pressure regulating valves that use instrumented compressed air instead of process fluids. Many companies that produce pressure reducing valves have now developed into regulating valve manufacturers. The use of regulating valves continues to evolve in terms of quantity and complexity, and improvements in the valve bodies and accessories of many valves can be used to solve a wide variety of problems. The intent of this manual is to familiarize engineers with the entanglement and factors of regulating valves, and to help instrument engineers select the best valves, actuators and accessories for their applications.
The regulating valve belongs to the series of control valves. The main function is to adjust the pressure, flow, temperature and other parameters of the medium, which is the final control component in the process loop.
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Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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