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By Dan Hebert, PE
To some, condition monitoring (CM) means installing vibration sensors on a few critical motors, and then having a maintenance technician with a handheld data logger check sensor readings on a more or less regular basis.
To others, such as Romel Bhullar, senior technical fellow/director at the engineering and construction giant Fluor (www.fluor.com), CM is a very big deal, requiring a systems approach. "At Fluor, working as systems integrators on mega projects, we routinely incorporate conditioning monitoring solutions to control and manage capital assets," says Bhullar. (Figure 1)Besides huge upfront capital layouts of several hundred million dollars or more, these assets are directly responsible for delivering very valuable products like several hundred thousands barrels per day of petroleum or billions of cubic feet of natural gas. Unplanned interruptions can shut down operations and cost companies millions," adds Bhullar.
Condition monitoring to keep modern process plants up and running are necessarily complex. "A conditioning monitoring project typically involves integrating and marrying diverse and competing commercial technologies, systems and parameters," explains Bhullar. "It also requires very high-speed, real-time input monitoring, signal conditioning and processing. We have to deal with different sensor suppliers, vibration systems and system integration problems—using a variety of networks, communication protocols, media, servers, and application hardware and software."
However, it pays off, especially in process industry applications, where plant shutdowns due to equipment failure can cost millions of dollars per day. The dollars and the challenges may seem daunting, but the rewards can be significant, and there are ways to cut the project down to a manageable size.
While a plant-wide CM and asset management system isn't a simple project, the approach to it can be fairly straightforward, according to Michael Gurney, co-CEO of Concept Systems (www.conceptsystemsinc.com), a systems integrator in Albany, Ore.
"When it comes to the actual implementation of a CM solution, there are two options," he advises. "The first is using control hardware already in place, and the second is equipping assets with new instrumentation and controls."
Much hardware installed in a plant already has diagnostic capabilities. "In virtually all cases we've looked at, there are capabilities already on the plant floor for capturing data on an asset, but most go underutilized," says Gurney.
Sometimes, you don't even have to install sensors, as everything you need may already be there. InduSoft (www.indusoft.com), for example, installed a SCADA system at the University of Texas in Austin. "The system monitors more than 1200 meters from more than 100 buildings on the campus," explains Fabio Terezinho, InduSoft's VP of Consulting Services. "The InduSoft system combines real-time data acquired from an OPC server with historical data retrieved from the historian, and displays information from electrical, chilled water, domestic water and steam on dashboards—and makes the information available to remote users anywhere via a web browser."
The system also generates reports with a log of events, such as calibration/verification of the meters, which is used to schedule preventive maintenance and check the integrity of the data. Alarm and remote notification allows the university to detect and fix defects in a timely manner. According to InduSoft, installation went smoothly. "Integration of the open architecture InduSoft Web Studio with third-party systems previously installed at the site was straightforward," says Terezinho.
Another example of a relatively easy condition monitoring implementation occurred at Centro Energia Teverola (www.centroenergia.it), a 150-MW combined-cycle cogeneration power plant in Teverola, Italy, about 20 miles north of Naples. The plant already had CM sensors installed on instruments and valves, all wired into the existing legacy control system. But it was experiencing unexpected performance degradation because of clogged filters on the gas turbines, and the legacy system wasn't helping.
To obtain the advanced analysis needed to identify the problems, Centro Energia installed Emerson Process Management's (www.emersonprocess.com) AMS Performance Monitor. Emerson wrote a macro to acquire the necessary data from the legacy control system's historian. (Figure 2)Data is sent to Emerson's centralized service site in Teesside in northeastern England, where Emerson analyzes the data and provides Centro Energia with actionable information. Vincenzo Piscitelli, general manager at Centro Energia, reports, "The return on investment was very fast. A single filter change has already paid for this service for two years."
Some plants may already have a conditioning monitoring system that isn't doing the job. Vectren (www.vectren.com), a power company in southwest Indiana, wanted to monitor more than 500 existing assets. Vectren's engineers were using a combination of software and spreadsheets to analyze more than 15000 equipment readings. The trend analysis software checked for problems and reported instances when assets were broken or not running efficiently. Alarms indicated problems that needed immediate attention, but the existing approach had several drawbacks.