Knowing what you're looking at is the most important thing, but a sharp focus can help you get there. Defining, organizing, prioritizing and understanding alerts and alarms is one of the most critical jobs in process control. However, perhaps because so many applications are isolated, inadequate and dangerous alarm practices can persist for years. Sometimes it's too few useful alarms, but more often it's floods of duplicate and unnecessary alerts that were thrown in for compliance and convenience's sake rather than ensuring safe operations.
The solution begins with an inventory of processes and alerts, but it continues with assessing and prioritizing alarms, incorporating more helpful database software and HMIs, and training staff to follow these improved procedures.
For instance, Vale's Copper Cliff nickel smelter in Sundbury, Ontario, runs two flash furnaces, which take in 4200 tonnes of dry solid charge (DSC) ore powder per day, and flash-smelt it into nickel matte product, sulphur gas for fuel and iron slag. However, several years ago, engineers in Vale's Ontario division started an alarm rationalization project because the two furnaces were generating more than 17,000 alarms per day on average, most of which weren't understandable to the operators, and which didn't lead to useful action.
"Previous rationalization projects tried to reduce alarms, but always ended up adding more," says Gerry Seguin, Vale Ontario's senior automation specialist. "Then a consultant from the Engineering Equipment Materials Users Association came in for a seminar; gave a report on consequences that really hit home; and showed the alarms weren't the operators' faults because they hadn't been given the tools for their job. After that, we were able to get financing, resources and people, including bringing back two pensioned operators full-time to go over all alarm interactions."
So Vale Ontario implemented EEMUA's Publication 191, "Alarm Systems--A Guide to Design, Management and Procurement," and ISA's ISA 18 alarm management standard; evaluated and reduced alarm system loading on the two flash furnaces, and redesigned its alarm systems to assist operators. Vale also partnered with Invensys, and adopted its PAS Alarm Management Software database, which works with its existing Foxboro I/A Series process control software to download approved alarms to the application's field controllers.
As a result, alarms on Copper Cliff's two flash furnaces dropped to a daily average of just 66, which exceeded EEMUA's average alarm rate benchmark for steady operation. "We also researched to ensure that operators had enough time between alarms and trips to respond effectively," adds Seguin. "Since the initial project in 2007-08, all new alarms go through an alarm manager to make sure they meet the criteria we've laid out, which is like a risk assessment chart that evaluates likelihood, criticality and potential damage, and sets priority levels."
Seguin reports that Copper Cliff is continuing to improve its alarm and HMI philosophy and rationalization process and is applying it to other areas of the smelter, including a new replacement nickel converting unit it will commission this September.
Pull Pointer Out of Panel
Similarly, DTE Energy's Greenwood Energy Center (GWEC) in Avoca, Mich., has been upgrading its DCS from a 1990s-era Westinghouse Distributed Processing Facility (WDPF) system and lightbox displays to ABB's Process Portal A (PPA) 800xA DCS, but first decided rationalize and reorganize several thousand alarms and related devices and software.
"Previously, many of our DCS alarms weren't rationalized. They were just characterized as high or high worse, and so we had a lot of noise and chattering alarms that were only fixed occasionally," says Kip Dobel, senior engineer in GWEC's Engineering Support Organization. "In fact, operators determined unit status by the different volumes of alarms and not actual alarms. Some also found interesting ways to silence nuisance alarms, such as jamming a pointer in their board. Pages of alarms would scroll by on a unit trip, making it very easy for an important alarm to get lost in all the noise."
Located 60 miles north of Detroit, GWEC is an 800-megawatt "peaker" oil and gas plant, which helps power the grid when demand is high. This means it ramps its electrical production up and down more than other plants.
To focus on important alarms and eliminate chatter, Dobel reports that GWEC began migrating from WDPF to PPA 800xA in 2010, and installed Matrikon's Process Guard software to help with post-event unit trip analyses. PPA 800xA included customer libraries, seven operator consoles, three engineering work packages (EWPs), domain and 800xA controllers, and AlarmInsight operator assistance software for 800xA, which grew out of collaboration by ABB and Matrikon. GWEC also runs OSIsoft's PI historian software to document high-priority alarms and check on operating devices.