Honeywell Industry Solutions announced recently that it has analyzed performance data from more than 100,000 control loops at 350 manufacturing facilities since the introduction of its Loop Scout control loop management service five years ago.
The Web-based Loop Scout service can help process industry customers identify control loops that are performing poorly, along with those that have the greatest impact on overall plant performance, the company says. According to Honeywell, attention to control loop issues can pay big bottom-line dividends.
“We get anecdotal feedback from customers all the time, that they saved $625,000 by addressing a certain part of their process that was oscillating, for example, or they fixed an input feed to a reactor that had a sticky valve, and it saved them $1.7 million,” says Randy Miller, Manager of the Loop Management Services Group, for Phoenix-based Honeywell Process Solutions. “We had one customer that saved in excess of $10 million through a one-year program of systematically addressing loop problems,” Miller contends. The savings came through a combination of increased production, lower energy costs and reduced maintenance costs, he says.
Loop ranking
With Loop Scout, control loop data collected at customer plants is automatically transferred via Internet links for analysis by Loop Scout’s statistical engine, which resides on a central Honeywell server. Results are accessible to customers online using standard Web browsers. “We can determine a wide range of performance characteristics,” says Miller. “We rank control loop performance, and we have pattern recognition technologies that detect valve stiction, for example, and the degree to which the valve is sticky.”
A variety of vendors offer control loop performance software and services, such as PlantTriage from Hubertus, Wisc.-based ExperTune Inc., for example, and ProcessDoctor, from Matrikon Inc., of Edmonton, Alberta, Canada. But according to Miller, one thing that differentiates Honeywell’s Loop Scout service is the extent of its centralized database, which is used for data mining, benchmarking and algorithm development. “To our knowledge, this is the largest repository of control loop data in the world,” he says. “Every single algorithm we have has been optimized and tested against 100,000 data sets.”
Loop Scout can provide a picture of how valves and devices are operating across an entire plant, as well as guidelines for prioritizing repairs and optimizing plant performance, Honeywell says. Many customers use the service as a way to reduce maintenance on valves that may be due for servicing on a preventive maintenance schedule, but in actuality, are still functioning correctly, Miller notes. “For every valve that gets pulled, the cost is $2,000 to $3,000, whether the valve is good or bad,” Miller observes. Likewise, the service can identify valves that are functioning poorly and should be serviced, even though they may not yet be due for regular maintenance.
Spotting oscillations
Loop Scout’s ability to help engineers more easily spot control loops that are oscillating—one of the most common loop failure modes—is becoming increasingly valuable, given industry downsizing trends, says Miller. Staff sizes of engineering groups charged with control loop management have shrunk by about 40 percent over the past 10 years, Miller estimates. According to recent Honeywell surveys, plant engineers today are often responsible for more than 400 control loops each, significantly more than in the past. And as engineers take on additional responsibilities, loop management can easily slip down the priority list. “Addressing a loop that is oscillating is rarely going to get the same amount of attention as, let’s say, a DCS (distributed control system) that has a red blinking light on it,” as Miller puts it.
Unlike some other problems that can shut down a plant or a process, an oscillating control loop is not a catastrophic failure, Miller concedes. But having multiple poorly performing loops across a facility can certainly cut into a plant’s profits, he points out. By using a service such as Loop Scout to address their most serious loop problems first, and then working their way down the list, engineers can help their plants head off some of those lost dollars, Miller says.
