Controls and process applications can be restored

Restoration possible: Many distributed control systems (DCSs) are rapidly aging and risk breaking down. Luckily, there are many tools and innovative methods for supporting and breathing new life into controls and process applications

By Jim Montague

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The project was completed in phases with first-phase implementation during a three-month, off-crop season in January to April 2011, which was enough time to remove the old Provox DCS and replace it with the new, integrated system on Komati's Extraction Line 2. "All the other systems remained the same, and System Platform was built on top of the existing systems to facilitate integration," says Samantha Rabé, CSI's systems engineer. "Overall equipment effectiveness (OEE), LIMS, Provox and DeltaV data were integrated into System Platform to show KPIs on the InTouch dual-screen displays."

Pieter san Tonder, Tsb Komati's instrumentation engineer, reports, "We're now able to manage low throughput because, for the first time, we can measure it accurately. Real-time feedback to record the plant's lost-time availability (LTA) and overall time efficiency (OTE), and have it available on managers' desktops was unthinkable a decade ago. System Platform's ability to integrate and consolidate data across the different systems and deliver it in a presentable format enables us to be proactive rather than reactive."

Meanwhile, on the software side, PCN Technology Inc. reports it's developed software algorithms and hardware modules that can be dropped into a legacy control system, and allow it to be retained, but still enable it to be accessed by an Internet protocol (IP) network. "This allows migrations at a more rapid pace because we don't have to rip and replace so much," says Daniel Drolet, PCN's executive vice president. "For example, users may have an old Seriplex or RS485 network that works OK, and we can plug into its PLCs, head or service center router to add multidrop IP communications, while still allowing the serial network to continue."

Rich Clark, principal applications consultant in Honeywell's Lifecycle Services business unit, reports, "Many DCS migration plans are using advances in the IT world, such as virtualization, open standards-based devices and HMIs using thin-client computing and eServer produces to put control data in secure zones for viewing by browser-based systems. For example, in the past three years, more migration projects are using virtualized data processing that doesn't need to be implemented all at once. There are many large base stations and applications in Windows XP and Windows 2003 with three- to five-year-old hardware, but Microsoft won't support XP after next year, so many users will need to migrate those stations. Virtualization gives users the flexibility to stretch out their migrations and go longer between the time they have to touch wires and reengineer systems."

"Rip Off the Band-Aid"

To finally upgrade its consoles and layer on its new DCS, Benecia's engineers added a pair of redundant Experion Servers (ESVTs) to their 73-node LCN, and then added two Icon stations to test them on their production system. As these worked well, they upgraded their engineer console. Finally, they added a second temporary console in the center, reaching a total of 10 Icon stations in their system. These provided stations for engineers and operators to preview and test the converted graphics, while still maintaining enough stations for operations in high demand situations.

"Once all three chunks of A's complex graphics were converted, we were ready to train our A console operators. Our graphics vendor trained the operators, and then they were physically relocated to the new center console," added Plaskett. "We left their console in place for another seven weeks, making sure all operators had a chance to work their shift cycle at the new stations before removing the stations they felt most comfortable with. These stations were not side-by-side, but in an emergency, the operator could go back to the console and operate the refinery. This satisfied our space limitation challenge. Once the seven weeks passed, we began demolishing and replacing the old A console, and these operators were moved back to their home when it was upgraded. This method of training and relocation also allowed us to satisfy our seven-week shift schedule staffing challenge."

Next, with the B cluster graphics completed and B operators trained on Experion, it was time to upgrade the B console to Icon stations. However, this could not be done until the old TPN Bridge was removed and a second set of Experion servers put into operation. This bridge removal was preceded by months of preparation. LCN nodes were relocated within cabinets, so nodes on the same cluster were in close proximity and could be re-cabled together carefully.

"Our detailed procedure for making all of these moves included over 120 LCN cable moves. Besides moving and re-cabling all of these nodes, the exact procedure we developed for removing the bridge was reviewed and blessed by Honeywell," explains Plaskett. "On D-day, all operators were moved to universal stations (USs) or used NW on ESTs. The TPN Bridge nodes and switches were all simultaneously powered off. The system complained loudly for two minutes, noting which nodes were now missing from each LCN. LCN re-cabling was done to eliminate these boxes from the LCNs. A console ESTs could not be used until all points were re-primed, since many internal IDs it had known about were now gone. It had to discover these points now as DSA points. The new B cluster servers had to be started up and primed with the points on its LCN. Once primed, they could each offer up their points on DSA. After several days of re-priming, HMIWeb graphics could be used again and B console stations could now be upgraded to Icons.

"At this point, the console upgrades could continue. The B operators who had been at their B console USs could be moved back to the center console. The USs were replaced with Icons, and the B operators were moved back to the newly converted B console. Throughout all of this, OM operations had been a subset of the B complex. After allowing the A and B complex operations to line out over a few months, the OM cluster was finally broken off and created."

Finally, Plaskett reports finding that seven weeks was enough time for Benecia's operators to train on Experion. "Though we heard of other locations where old USs and new Experion stations sit side by side for years, we essentially had to ‘rip off the Band-Aid' and remove the old stations to move through the project and complete it," she says. Also, NW on the Icon has been a blessing and a curse because operators sometimes fall back to using it when they don't think the Experion graphic is responding fast enough. So we're glad it's there to give them a sense of security, but the black NW and gray HMIWeb graphics are a continual source of discussion at our plant. Also, support is becoming a big issue, as we have to do patching, error logs and network support. And simple point rebuilding now requires an extra step, DSPPrime, and even AM point algorithm changes require new priming!

"However, we achieved a successful project completed within the challenges of space, staffing, resources and timing. We maintained an integrated view for our operators. We now have a modern, highly functional operator interface. We've continued evolution along with our Honeywell system, and our investment is secure."  

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