Final control

What’s the latest on control valves? Editor in Chief Walt Boyes takes a look at the current marketplace for the final element that all control stuff is aimed at—the control valve that produces the end result.

By Walt Boyes

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Mark Wells, from RunFactory.com, agrees that smarter controllers provide many benefits. He sees secure communications and embedded configuration management as keys to better operation of control valves.

     FIGURE 1: A REALLY BIG VALVE
  Fisher Control Valve
 

This 7-ft tall valve’s real claim to fame is its built-in tuning tools (See Sidebar below).

Dick Morley, guru par excellence, agrees with Fillion about materials. “Materials and process will be the first tipover for nano,” he says.

Imagine nano-engineered, wetted materials specific to the application, he urges, also suggesting the age of single-loop control may be done. “The math seems to indicate that the number of sensing elements is key, not the accuracy,” he says.

Valves themselves may be going away, says Nels Tyring, the father of system integration in automation. “Energy has become too expensive to waste, and control valves, by and large, are devices that dissipate energy in the form of pressure or flow by forcing fluids and gases through small orifices to remove energy that was imparted to them at some point upstream,” he says.

So what will be done? Tyring says, “The development of the AC drive and its reduction in price over the past two decades has given industry an energy-efficient option to the control valve, and one that is not adding energy to a process that you are going to have to dissipate somewhere else along the process system.”

Tyring sums up his theory, “If you look at the control valve industry from this standpoint, the market is to a large extent for valves that reduce either pressure or flow, and that market is rapidly shrinking due to higher costs of energy and improved and increasingly inexpensive ways to avoid its waste.”


The Big Valve

On the exhibit map of the 2006 Emerson Exchange is a small circle on the right hand side labeled “Big Valve.” It is, indeed, a big valve (See Figure 1 above). But it isn’t the big iron that is most interesting; it’s what Fisher’s valve experts have done with the actuator tuning. “Most control valves that are used for anti-surge service in the oil and gas industry have significant overshoot or undershoot problems when they have to move quickly from one position to another,” says John Wilson, oil and gas industry manager for Fisher Controls. “So what we’ve done is provide some very simple tuning tools that are built into the valve control software. Using a minor loop for feedback inside the actuator’s feedback loop, we can prevent overshoot or undershoot, even at very small openings, without introducing heavy damping into the system. This is a big advance for control valve actuation.”

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