In any process industry, the use of a control valve is an essential parameter.
To achieve world-class reliability and maximize overall process efficiency, valve performance is an essential element.
These control valves in the process loop actually move the valve stem to regulate the process performance which is very important.
Selecting the appropriate final control element valve control is the most essential concept to achieve excellent performance for the application required to maintain its performance over time.
Valve performance is influenced by various process parameters such as flow, level, pressure, temperature, etc.
What factors affect valve control performance?
Valve control performance is a complex interaction of these factors.
Careful consideration of each factor is necessary to verify the operation of the control valve as a control of the equipment process as desired.
However, continuous monitoring and periodic maintenance are necessary to maintain valve performance over time.
The performance of the control valve is affected by various factors as shown below:
Stream features:
The selection of flow characteristics must meet the process requirements to provide accurate control.
Different control valves show different flow characteristics:
1- Characteristics of linear flow
2-Features of equal percentage flow
3- Features of fast opening flow
Valve control size:
The size of the control valve is very important according to the flow rate of the process fluid. Here, proper valve size is essential to achieve nominal flow control.
Because an improperly sized control valve results in poor control, cavitation, insufficient control range, or excessive pressure drop. Care must be taken in the size of the control valve.
valve type:
Different types of valves such as globe valves, butterfly valves, ball valves and plug valves offer individual flow characteristics that are suitable for specific process applications.
These valves have very specific designs and mechanisms that affect their performance.
However, choosing the right valve should include various factors such as flow rate, pressure drop, and. Precision control that is essential for exceptional performance.
milk trim:
The design and configuration of the valve trim, including the size and shape of the plug, seat, and other internal components, can affect the control accuracy and control range of the valve
Pressure drop:
Usually, the pressure drop in the control valve is defined as the difference between inlet pressure and outlet pressure.
Excessive pressure drop across valve control due to reduced efficiency, poor control, and. Minimizing system capacity and…
However, it is necessary to consider the actual pressure drop throughout the system.
Excessive pressure drop can lead to cavitation or erosion, while low pressure drop may limit the control power of the valve.
properties of fluids:
Controlled fluid properties such as fluid viscosity, fluid density, temperature, etc. Corrosivity may affect milk performance.
For this purpose, some process fluids require special valve design and decorative materials to prevent damage or erosion of valve components.
Cavitation and flushing:
Control valve cavitation and valve flash are unacceptable phenomena that exist in a control valve due to rapid pressure drop.
Due to these phenomena, the control of the valve may decrease and may be damaged.
Cavitation and valve flash can be reduced by selecting a proper valve and accurate sizing.
A hole in the valve stem occurs when the valve pressure drops below the vapor pressure, leading to the origin.
On the other hand, valve flash is somewhat similar to valve cavitation, which assumes the instantaneous vaporization of a portion of the liquid.
But both cavitation and flushing phenomena can worsen valve performance and damage the valve.
Valve control actuator or actuator:
Actuator is an integral component of valve control that calculates the valve stem position to open or close in response to a control signal received by the controller.
Speed, accuracy and control are the most essential parameters for overall performance.
Poor actuator performance results from stagnant response time and incorrect control.
valve positioner or itopi positioner:
Itopy positioners are attached to control valves to improve control accuracy by adjusting the valve control position in response to the control signal received by the controller.
Here, the type of valve positioner and its function are among the most essential factors.
An electronic controller is connected to an electronic positioner to adjust the position of the control valve according to the desired set point.
Instrumentation and control system:
The system operation consists of a controller and feedback loop that affects the quality of the valve to keep it at the desired set point. The overall effectiveness of valve control can be influenced by the performance of the control system, including the level of accuracy of sensors, controller tuning, and component communications. .
Maintenance and calibration:
Regular maintenance and calibration of control valves is essential for consistent performance over time, and inspection of control valves is essential to ensure they continue to perform optimally over time.
Valve control maintenance:
Regular maintenance is essential to resume proper valve operation over time.
Over time, the wear and tear of the valve components reduces the performance.
Environmental factors:
Environmental conditions, such as temperature, humidity, and exposure to a corrosive environment affect the performance and longevity of the valve.
Piping plan:
The placement of piping and necessary fittings around the control valve may affect pressure drop and flow patterns, which can affect system performance.
Noise and vibration:
Since control valves produce excitable noise and vibration.
Periodic management or maintenance is necessary to prevent any damage or problems to near field tools and personal safety.
Safety and reliability:
Basically, equipment safety and reliability are essential and dominant for critical processes.
Operational conditions:
The control valve used must be capable of handling inconsistencies in process conditions such as changes in fluid flow rate, temperature, composition, and pressure that can affect valve performance.
Properly designed control strategies can help reduce these effects.
Material Compatibility:
The material used to make the valve must be compatible with the various types of process fluid to prevent corrosion or destruction.
In applications with abrasive or corrosive fluids, erosion and corrosion can reduce valve performance over time. Choosing the right material and maintenance is very important.
Mechanical adhesive:
Mechanical friction usually refers to static friction to stop the valve from moving smoothly for a small or low applied control signal.
This can help manage inaccuracies and fluctuations.
Piping design, installation and orientation:
To achieve excellent valve performance, accurate installation and orientation in the pipeline is essential.
In most cases, improper installation and piping design may cause pressure fluctuations, misalignment, and turbulence, which also affect valve performance.
Setting the control loop:
The control loop setting includes proportional (P), integral (I) and derivative (D) settings (PID).
This ring adjustment improves the valve’s ability to accurately create the desired set point.
Kiasanat is a supplier of all types of valve controls, Samson valve controls, Samson three-way valve controls, Fisher valve controls, Masonilan valve controls, Honeywell valve controls, Samson pneumatic valves, Isfahan steam pneumatic valves, etc.
Other content:
Valve control sizing
Choosing the right steam trap
The difference between male connector and female connector
Control valve packing
Valve control inspection
Important factors in choosing valve control
