DCS Migration for Functional Upgrades
USA Yeast produces yeast products for bakery, ethanol, and other food production markets. It was organized in 2003 by Mike Lavallee and a group of investors to compete in an industry dominated by producers based outside the U.S. The company’s only production facility is located in Hattiesburg, MS, in a 37,000 square foot plant that was built from the ground up with modern and fully automated production.
Given the critical role that yeast plays in the production of bread and other baked goods, producers insist on dependable and consistent performance from batch to batch. With that in mind, Lavallee and his associates designed the manufacturing strategy to provide designed-in product consistency achieved through sophisticated process control systems combined with aggressive quality assurance.
Early retirement for DCS
The plant was originally built using a Rockwell ProcessLogix control system running on Allen-Bradley hardware. Unfortunately, the plant wasn’t in operation for very many years before the system began to show its age. The company wanted to take advantage of some of the growing capabilities of smart instrumentation and improved transmitters, particularly recent advances in condition monitoring and diagnostics of temperature sensors possible with fieldbus communication. However, the control system could not support the changes, and those involved said that Rockwell had not indicated that system upgrades would support those capabilities.
“We felt that we were at a dead end and needed a system that could grow with us and provide a clear migration path,” says Stacey Miller, applications engineer for USA Yeast. The company approached Honeywell Process Solutions to analyze the configuration of the existing system in light of the specific needs of the process and business drivers involved. After formulating a solution that would require a minimum of equipment change-over, Honeywell presented a proposal detailing the hardware, software, and processes that would be required to perform the migration successfully. One element of the proposal that made it easier for USA Yeast to embrace was that there was no need for new graphics, rewriting any control code, or removing any wiring or I/O connections. In addition, the most critical elements were identified clearly to mitigate risk.
USA Yeast operates 24 hours a day, seven days a week so the cutover had to be completed quickly to minimize any possibility of production disruption. The plan included doing the actual change-over during a weekend when shutting down the system was least critical to production.
To perform the migration, Honeywell supplied redundant servers, controller expansion hardware, Experion software, and engineering services. During the actual migration, several critical issues had to be resolved:
Moving the CL5555 processors and DeviceNet cards that were paired with a C200 processor in three racks to their own racks;
Editing all exchange blocks for the new ASA (automation system architecture) path as a result of moving the processors and cards;
Editing the CL5555 programming for the new ASA path for the messaging to the field PLCs; and
Flashing all the cards in the system with the Honeywell firmware.
As planned, the final migration cutover was performed over a weekend to limit process downtime. This required a very detailed strategy, careful scheduling, and long workdays to squeeze four days worth of work into two. USA Yeast worked a continuous 24 hours performing the long process of reloading all the Fieldbus points and reactivating the 350 SCMs (sequence control modules). This allowed testing to begin on the second day and the company resumed truck loading operations.
Minding the details
The success of this project can be attributed to detailed planning, careful execution and building the right team. Identifying all the project requirements, risks, and customer expectations early in the discovery phase is also vital to positive performance.
“With the support of Honeywell, we have successfully migrated our Rockwell ProcessLogix control system to Experion,” says Miller. “We now have greater access to real-time information and analysis tools to make faster and more effective decisions.”
With the migration, USA Yeast cited a number of specific improvements, including:
Improved access to plant information;
Improved operator effectiveness;
Fieldbus issues resolved;
Full integration of transmitter capability improvements;
Detailed migration path to allow for business growth; and
Clear channels for technical support going forward.
Miller concludes, “We are very happy with the overall migration and unbeatable performance we see with the Experion system. We see a clear growth path for our business and now have a product that will enable us to do so in a seamless way.”
|Joe Paradiso is project manager is project manager for Honeywell Process Solutions. Reach him at email@example.com .|
Advances in temperature sensor diagnostics
In an article entitled “Turning Up the Heat” in Control Engineering Asia , Jonas Berge (Emerson Process Management) discusses some advances made in temperature sensor diagnostics that are facilitated by fieldbus networking. Read the complete article at http://tinyurl.com/kruvc7 . Here’s an excerpt:
“Diagnostic technologies now allow plants to leverage thermocouple condition monitoring and failure prediction features that were previously unavailable in transmitters. Deployment of these technologies helps reduce process downtime and decrease energy costs. Specifically, the two open technologies brought together for detection, delivery, and display of diagnostics are Foundation fieldbus and Electronic Device Description Language (EDDL).
“Conventional two-wire, loop-powered temperature transmitters with a 4-20 mA analog output have a power limitation as they must consume less than 4 mA. This limits processing power of the microprocessor, as well as the level of complexity of the device firmware.
“In comparison, two-wire, bus-powered fieldbus devices do not have this power limitation; a temperature transmitter can consume 12 mA or more, if need be. This enables the use of a more powerful microprocessor, and subsequently more sophisticated device firmware, allowing for new powerful diagnostics.
“As a further advantage, and unlike other communication protocols used in temperature transmitters, devices using Foundation fieldbus have a synchronized real-time clock that enables process and diagnostic alarms to be time-stamped in the transmitter.
“The time-stamps allow event recordings to be accurate, even if the communication is not instantaneous. Alerts are sent when state changes. This is the most efficient use of communication, eliminating the need to wait for polling from the system.
“Device diagnostics like those for thermocouple degradation, temperature tracking, and statistical process monitoring are prioritized and categorized as per NAMUR NE 107 recommendation. This allows the system to alert the right person without flooding others in alarms.”