Hello, industrious readers! Industrial plants and manufacturing industries often require control over the flow of certain fluids, air, and other substances. And for this reason, valve control plays a significant role in these sectors, ensuring that processes run smoothly and efficiently. But how do these systems work? How do we optimize these valves to suit specific needs effectively?
This is where valve control strategies come to play. We can describe them as tactics or methods that are employed to optimize the performance of valve systems; and they have proven to be a game-changer in several industrial processes.
What Are Valve Control Strategies?
Valve control strategies can be explained as a series of operational methods used to control valves’ performance and improve their efficiency. This concept is not new, it has been in existence for years, forming a basic foundation for industries like oil and gas, water treatment, food and beverage, pharmaceutical, and many others. However, due to rapid technological advancement, the procedure of optimizing valves has become more sophisticated and effective.
Types of Valve Control Strategies
There are different types of valve control strategies that can be applied to different scenarios and settings. The type of strategy used depends heavily on the process requirement, budget, and valve type:
1. On-Off Control Strategy: In this strategy, a basic control loop uses a controller that monitors the process variable (like pressure, level, temperature). When the variable exceeds the set limit, the controller sends a signal to the valve (either to fully open or shut) to counteract the change. Simple and efficient, this strategy is perfect for scenarios where precise control is not required.
2. Proportional Control Strategy: As a step up from the on-off control strategy, the proportional control allows the valves to not only be fully open or closed but also be in any position in between. The controller still monitors a process variable, but now the valve moves in relation to how much the process variable deviates from a set point. It allows for a more precise and smoother control.
3. PID Control Strategy: The PID control (Proportional-Integral-Derivative) is the most complex of the three. It also monitors a process variable and adjusts the valve’s position based on proportional, integral, and derivative responses – this strategy is generally employed when very precise control is necessary.
Each of these strategies offers different levels of precise control. The decision to select any of them depends on process requirements, valve type, and resources.
But, no matter the strategy you choose, there are common factors that you need to consider:
- Precise Actuators: Hire experts or train your team members to precisely calibrate actuators. Improper calibration may lead to inefficiency and a reduction in output.
- Valve Positioners: For precise control, valve positioners are often used. They receive the signal from the controller and strategically manage air supply to the actuator for the desired positioning.
- Valve Authority: In any system, a valve should always have the correct “authority,” or ratio of pressure drop across the valve to the total pressure drop across the system. High valve authority means the valve regulates the flow rate well, and a low valve authority means the system’s dynamics influence the flow rate.
Your control strategy should be revisited regularly. It is also beneficial to maintain your systems adequately – Regular inspection, support-level agreement with suppliers, and a robust response plan should be in place for emergencies.
Conclusion
Valve control strategies are now an integral part of various industries. The careful selection of strategies can lead to optimized processes, reduced costs, and increased business performance. No matter what area you work in or what kind of machinery you operate, employing the best strategy will always spell success.
Sources
1. “Control Valve Basics: Sizing and Selection”
2. “How To Improve Control Valve Reliability”
