Plant Services - August 2007 - (Page 32) TECHNOLOGY TOOLBOX Control valve diagnostics Health monitoring can eliminate stiction, wrong-sizing and excessive wear by putting in advanced controls,” says Buckbee. “However, onitoring and prioritizing maintenance targets you can’t achieve stability if you don’t correct the underlying is becoming increasingly automated and criteriaproblems in valves, instrumentation and loops.” driven. Individual valves can monitor their own Stiction affects efficiency and produces plant upsets. Prohealth and call for help when they exhibit sub-optimal percesses can be constrained by a valve that’s too small. A comformance. This increases throughput and uptime, and it deponent might have been designed for one purpose but, over creases vlve maintenance, technician time and energy costs. time, the materials, production or process have changed. Underlying technologies: An enabler of control valve Correcting these problems can be an inexpensive way to inoptimization is standards-based, interoperable fieldbuses. crease production and plant performance. “Fieldbus is taking off like crazy. Some consider it a mature Poor controller tuning and filtering can move control market, but billions of dollars are still being spent every year valves more than necessary. This reduces useful life and inon the technology,” says Robert Dunlap, founder of Core duces process upsets. When you can see that Global Consulting. “Its greatest benefit is the loop tuning is damaging a valve or fluid haninformation it collects for maintenance.” dling system, you can correct it. Manufacturers can chose from multiple Triggers and Optimization outlook: Control valve open protocols, so monitoring and automation filters make it optimization remains a priority for several providers such as Emerson, Honeywell and Invensys use multiple languages. Emerson, easy to establish reasons. Knowledge leaves as the workforce and maintain retires. Equipment is aging, which makes for one, offers HART, Foundation fieldbus, extending the asset life more important. ForAS-i, Profibus DP and DeviceNet cards. best practices. eign competitors, who share our open comGeorge Buckbee, marketing director at munications standards, increase the emphasis ExperTune, agrees that open communications on costs, production and efficiency. Predictive maintenance is the key to automated valve maintenance decisions. Most and systematic decisions provide answers to each concerns. control system manufacturers support the OPC interface in Dunlap acknowledges that some changes are politically their field devices. Once available on OPC, the data can be driven. “When a pro-environment administration is elected, shared anywhere. ExperTune’s PlantTriage, a performance being better stewards of the environment becomes a priorsupervision system, sits on top of the control system and ity. Oil and chemical companies might find themselves unuses OPC to pull real-time information into control loops. der greater scrutiny, and will pay more attention to packing Automated performance monitoring: Systems like flanges, accident and leak avoidance, efficient production PlantTriage make it easier to spot the bad actor valves and methods, and how they clean up the ground field.” control loops. This system performs 70 assessments on every Buckbee anticipates greater emphasis on bringing in key control loop and applies economic weighting to each loop information from a variety of systems and putting it into to determine problem criticality. Weighting shows where to context – not just the valve or control loop, but how the focus the maintenance effort. component affects the overall process. Having this contexTriggers and filters that consider valve type, economics tual perspective will make it easier to focus on achieving and baseline or threshold conditions make it easy to estabbusiness value and financial benefits. lish and maintain best practices. If a valve says it’s exhibiting less than 0.5% of stiction, you decide to react or not. Target correctable conditions: “An often overlooked E-mail Contributing Editor Sheila Kennedy, managing director of problem is trying to stabilize and solve process variability Additive Communications, at Sheila@addcomm.com. For more information, see: www.core-global.com www.expertune.com 32 M www.emersonprocess.com www.honeywell.com www.PLANTSERVICES.com www.invensys.com www.opcfoundation.org August 2007 http://www.plantservices.com/voices/technology_toolbox.html http://www.core-global.com http://www.emersonprocess.com http://www.invensys.com http://www.expertune.com http://www.honeywell.com http://www.opcfoundation.org http://www.PLANTSERVICES.com
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