Smart Pipe--One Bus to Rule Them All

What Revolutionary Technology Is Coming Along That Will Kill Fieldbus?

By John Rezabek

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The question came up on the fieldbus LinkedIn discussions last month, asking "What revolutionary technology is coming along that will kill fieldbus?" While wireless technologies are advancing and maturing, there still remain numerous applications it will struggle to overcome: control valves with a spring-opposed diaphragm, for example. 

The problem of standards convergence remains foggy at best. There are folks whacking away at super-batteries, energy scavenging, solar cells, even little windmills, but a "revolutionary" technology would have an impact on bus wars and wireless wars the same as the optical disk had on the VHS-Beta debate; virtually no one cares about video cassette standards anymore.

Those becoming weary of trying to chose the winning network for integration of their smart instruments are wondering, what killer idea is quietly cooking in some skunkworks that will make all our current consternations about busses and wireless standards irrelevant.

It could be smart pipe. What if the pipe and vessels that contain your physical process were embedded with sensors for flow, pressure, temperature and composition? No more vessel penetrations for themowells or process taps for DP cells. No more worries about plugging impulse lines or zero shifts. Distillation column temperature profiles would be continuous and automatic. Maybe we'd still want a few conventional analog pressure gauges and sight glasses to comfort ourselves, but the smart pipe would have the reach and redundancy to make the old stuff as often-used as your VHS player.

If smart pipes ever became a commercial reality, bus technology wouldn't be the only victim of a paradigm shift.

There was a time I joked about smart pipe, but it appears it may be more than just a fantasy. The federal government is funding studies at Illinois State, Northwestern University and elsewhere, seeking technology for leak detection in long drinking water pipelines. One way to detect potential leaks is to measure flow at the source and the destination, and compare them; if the destination measurement is less than that at the source, you might have a leak. But you could have hundreds of miles of pipe to examine, and you're tasked with trying to figure out precisely which part of the line needs to be dug up and repaired. But if sensors for flow, pressure and temperature are sufficiently cheap and abundant, readings at a large diversity of locations can be examined. They could validate each other to a large extent to diminish false alarms. And if 20 sensors upstream and 20 sensors downstream more or less agree on a sustained differential, you can bet you've found a leak.

Smart pipe has its analogs in biology. You can imagine your bloodstream and immune system as a sort of self-directed "smart pipe." The Northwestern study employs microscopic nanosensors embedded in the walls of 2-in. PVC pipe. These early prototypes are in lab-scale PVC pipe sections and "phone home" using wireless technology. But with cheapness and ubiquity, the nanosensors could pass data one to another like neurons.

If this technology ever became a commercial reality, bus technology wouldn't be the only victim of a paradigm shift. Our whole discipline has been built around the primary element (e.g., orifice plate)-transducer–transmitter–receiver model since the days of pneumatics. The "balloons" on a P&ID would largely go away, save for a dashed line to the controller and operator interface. The way we do measurement and control would be obsolete. Without individual devices that needed a pair of wires or a radio to connect them with the DCS, bus protocols and wireless solutions would become as relevant as your reel-to-reel tape player.

That said, I think our present-day practices are safe from obsolescence, at least for awhile. There remain a multitude of unsolved issues for smart pipe.

There may be other revolutionary technologies to "rule them all," but for the near term we'll have to keep agonizing over choosing the winner. See http://www.isws.illinois.edu/gws/sensor/smartpipe/ for more information. 

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