Intelligent, Standardized and Energy-saving Control Valves In Industrial Control
Jul 03, 2024
This article summarizes the current issues with control valves in industrial control, highlighting their development towards intelligence, standardization, rotation, miniaturization, and energy saving.
1.1 Intelligence and standardization
Currently, the intelligence of valves is mainly reflected in the application of intelligent valve positioners. Intelligent valve positioners enables functions such as self-diagnosis and remote communication of operating status. Conventional valve failures can be identified through self-diagnosis, reducing the requirements for instrument maintenance personnel and facilitating instrument equipment management. Intelligent valve positioners improve control valve accuracy. The widely used HART communication protocol enables on-site maintenance personnel to view and change valve parameters more conveniently. With communication protocols like HART, some valves can combine valve positioner control signals, feedback signals, PID control, and other functions, decentralizing control to the instrument site. This disperses danger, reducing its concentration in cabinets and indirectly mitigating the impact between cabinets on the entire device. The reduced transmission process also makes control more timely and efficient.
Standardization aims to reduce product varieties and shorten the valve supply cycle. When the valve's flow characteristics change, the valve positioner can be easily adjusted, improving the valve control loop’s accuracy. Thus, the requirements for control valve flow characteristics can be standardized. The control valve positioner can be adjusted via a unified communication protocol and other regulations, allowing for valve interchangeability by matching flow and control characteristics, even if the control valves have the same size and specification. Valves from different manufacturers can work together.
Standardized self-diagnosis and auxiliary software enable control valves from various manufacturers to diagnose operating status and analyze data through the same software. The standardized selection process uses uniform calculation steps. By inputting process data such as pressure before and after the valve, maximum flow, temperature, pipeline diameters, medium, and viscosity, the valve body, core, trim, and packing that match these parameters are selected to achieve high precision. Standardization may lead to future valves being designed modularly, allowing different standard accessories to be combined to form control valves with the required flow capacity. This will shorten the ordering cycle, unify external dimensions, and facilitate maintenance and repair.
1.2 Rotation and miniaturization
The development of materials science and manufacturing has led to the emergence of various new materials. New materials that meet the requirements of stiffness, toughness, and corrosion resistance have greatly reduced valve body weight. The use of various new actuators can reduce weight and external dimensions. For example, multi-spring diaphragm actuators can reduce weight and size while improving flow capacity. Modifying the valve structure and fluid flow path, such as changing from a straight stroke to an angular stroke, can reduce valve size, weight, and increase flow capacity. Recent double and triple eccentric butterfly valves have optimized valve stress through structural changes, achieving long-term sealing and greatly improving operational stability with relatively small volume, low flow path resistance, and a large adjustable ratio. Due to these advantages, the use of rotary valves in large-diameter pipeline industrial control is increasing annually.
1.3 Energy saving
Energy saving remains an important research focus in process industry control. Control valves consume energy to achieve control, and their energy consumption becomes more prominent with larger devices and increasing resource shortages. The byproducts of energy consumption, such as noise and vibration, also bring environmental and safety issues. Some methods, such as replacing control valves with variable frequency pumps, have been tried. However, since changes in speed also affect the head, the adjustable ratio range is limited in the process industry. Currently, energy-saving exploration of the valve itself mainly includes the following five aspects:
①Adjusting the structure of internal components to reduce the impedance of fluid passing through the valve, achieving control with a small pressure difference and thus reducing energy consumption.
②Adopting labyrinth sealing surfaces and replacing valve seat packing materials to improve sealing.
③Applying a balanced structure valve core to reduce the torque demand of the actuator structure, thereby reducing the air chamber of the diaphragm head or cylinder and reducing energy consumption.
④Using electric actuator structures.
⑤Applying self-acting regulating valves, which regulate clean process medium by using the pressure of the medium behind the valve as the power source for valve action, forming a self-acting control system to achieve pressure control behind the valve.
1.1 Intelligence and standardization
Currently, the intelligence of valves is mainly reflected in the application of intelligent valve positioners. Intelligent valve positioners enables functions such as self-diagnosis and remote communication of operating status. Conventional valve failures can be identified through self-diagnosis, reducing the requirements for instrument maintenance personnel and facilitating instrument equipment management. Intelligent valve positioners improve control valve accuracy. The widely used HART communication protocol enables on-site maintenance personnel to view and change valve parameters more conveniently. With communication protocols like HART, some valves can combine valve positioner control signals, feedback signals, PID control, and other functions, decentralizing control to the instrument site. This disperses danger, reducing its concentration in cabinets and indirectly mitigating the impact between cabinets on the entire device. The reduced transmission process also makes control more timely and efficient.
Standardization aims to reduce product varieties and shorten the valve supply cycle. When the valve's flow characteristics change, the valve positioner can be easily adjusted, improving the valve control loop’s accuracy. Thus, the requirements for control valve flow characteristics can be standardized. The control valve positioner can be adjusted via a unified communication protocol and other regulations, allowing for valve interchangeability by matching flow and control characteristics, even if the control valves have the same size and specification. Valves from different manufacturers can work together.
Standardized self-diagnosis and auxiliary software enable control valves from various manufacturers to diagnose operating status and analyze data through the same software. The standardized selection process uses uniform calculation steps. By inputting process data such as pressure before and after the valve, maximum flow, temperature, pipeline diameters, medium, and viscosity, the valve body, core, trim, and packing that match these parameters are selected to achieve high precision. Standardization may lead to future valves being designed modularly, allowing different standard accessories to be combined to form control valves with the required flow capacity. This will shorten the ordering cycle, unify external dimensions, and facilitate maintenance and repair.
1.2 Rotation and miniaturization
The development of materials science and manufacturing has led to the emergence of various new materials. New materials that meet the requirements of stiffness, toughness, and corrosion resistance have greatly reduced valve body weight. The use of various new actuators can reduce weight and external dimensions. For example, multi-spring diaphragm actuators can reduce weight and size while improving flow capacity. Modifying the valve structure and fluid flow path, such as changing from a straight stroke to an angular stroke, can reduce valve size, weight, and increase flow capacity. Recent double and triple eccentric butterfly valves have optimized valve stress through structural changes, achieving long-term sealing and greatly improving operational stability with relatively small volume, low flow path resistance, and a large adjustable ratio. Due to these advantages, the use of rotary valves in large-diameter pipeline industrial control is increasing annually.
1.3 Energy saving
Energy saving remains an important research focus in process industry control. Control valves consume energy to achieve control, and their energy consumption becomes more prominent with larger devices and increasing resource shortages. The byproducts of energy consumption, such as noise and vibration, also bring environmental and safety issues. Some methods, such as replacing control valves with variable frequency pumps, have been tried. However, since changes in speed also affect the head, the adjustable ratio range is limited in the process industry. Currently, energy-saving exploration of the valve itself mainly includes the following five aspects:
①Adjusting the structure of internal components to reduce the impedance of fluid passing through the valve, achieving control with a small pressure difference and thus reducing energy consumption.
②Adopting labyrinth sealing surfaces and replacing valve seat packing materials to improve sealing.
③Applying a balanced structure valve core to reduce the torque demand of the actuator structure, thereby reducing the air chamber of the diaphragm head or cylinder and reducing energy consumption.
④Using electric actuator structures.
⑤Applying self-acting regulating valves, which regulate clean process medium by using the pressure of the medium behind the valve as the power source for valve action, forming a self-acting control system to achieve pressure control behind the valve.
2. Conclusion
The development of regulating valves and industrial production process control occurs simultaneously. I believe that in the near future, regulating valves, as an important part of control, will become increasingly mature in function, and their application and maintenance will become more convenient.
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