Automation Vision Comes to Life

Digital automation helps BASF save time and money, achieve goals and improve loop checking

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By Carl Stumpe






The SAR unit at BASF's Hannibal, Mo., plant required only 10 hours to cut over to the new automation system.
BASF's agricultural chemicals facility in Hannibal, Mo., produces active ingredients and formulations for pesticides and herbicides using mostly batch-oriented operating units. Its existing digital control system (DCS) had become a barrier to applying advanced and cost-effective automation technologies. The system was more than 15 years old and the controllers and consoles frequently failed. In addition, the manufacturer no longer supported many of its DCS components.

The company's slogan, "Helping Make Products Better," encourages the use of technology to improve chemical processes. With this in mind, the Hannibal plant commissioned a DCS team to develop an automation and controls vision for the site. The team knew it couldn't meet its goals with the seven existing DCS local control networks (LCNs). Replacing these systems with leading-edge equipment and software would be a time-consuming and costly endeavor.

The team needed to find the best, most cost-effective automation architecture available. It also had to develop a strategy for replacing the old DCS control networks several at a time, rather than all at once. The team needed to accomplish these goals under tight time schedules, and to minimize production downtime, decrease startup time, overcome resistance to new work practices, and ensure adequate training for affected employees.

Four units' DCS were recently replaced with the DeltaV digital automation system from Emerson Process Management, Austin, Texas.

Technology leaps forward

Careful evaluation yielded two potential paths:

1. Upgrade to the existing vendor's latest DCS equipment and gain an incremental process control benefit, or

2. Install a new system based on proven technologies in process automation.

The decision was affected by economic factors and a desire for a less hardware-intensive DCS with integrated Foundation Fieldbus, Hart and Profibus DP technologies. BASF also wanted the life cycle cost efficiencies that come with using standardized PC platforms, which communicate with controllers through TCP/IP Ethernet networks.

After a thorough evaluation, BASF decided that replacing the existing DCS with a DeltaV digital automation system from Emerson Process Management would provide the greatest benefit.

Hardware differences

The Emerson DeltaV has a simplified structure: off-the-shelf workstations, standard IEEE Ethernet for the network, and rail-mounted backplanes with plug-in CPU, power supply and I/O cards. These features helped minimize purchase cost and provide flexibility, future compatibility and upgrade paths not available in a proprietary architecture.

The legacy DCS consisted of numerous gateways, nodes, termination boards, I/O boards, controllers, communications cards and consoles. One of the primary drivers for moving to a new system was to eliminate as much legacy hardware as possible. The team developed a modified version of Emerson's Flexconnect, which connects DeltaV I/O directly to the existing DCS termination panels using pre-built cables.

Automated configuration

Process control configuration, including interlocks, also posed a challenge since many people had worked on the existing programs in the past. Determining the original programmer's intent was critical to ensuring that the new code had the same functionality. The process had to be studied in detail to reestablish which actions should occur and why.

The legacy system relied on separate text and logic block code for interlocks, whereas the DeltaV interlocks are built into the device control modules. The operators can easily view them from a module faceplate. The new DCS's ability to show the current status of interlock initiating variables and to see the "first out" condition has proved to be very helpful.

 

These are the DeltaV PC-based operator workstations from Emerson Process Management, Austin, Texas, in the SAR/incinerators control room at the BASF agricultural chemicals plant in Hannibal, Mo. Author Carl Stumpe (left) points out a graphic to operator John Calhoun.

Financial ease

The Flexconnect approach allowed BASF to reuse legacy DCS cabinets, I/O termination boards and wiring. The marshalling system was untouched, and the new, compact controllers were installed in cabinet space vacated by the legacy controllers. This greatly reduced the engineering and construction labor required for the installation.

Prior DCS retrofits required a long time for cutover and startup, resulting in substantial downtime. On projects of similar size, DCS conversions took about three weeks. Retrofits for the DeltaV conversions took substantially less time , 10 hours for the Sulfuric Acid Regeneration (SAR) unit and eight hours for the incinerators.

The Flexconnect approach meant BASF did not need to construct a new rack room. The approach allowed use of low-cost DeltaV and Phoenix Contact Profibus I/O and reuse of existing control cabinets. The costs associated with electrical design and wiring were reduced by 75% and 80%, respectively. Loop checkout was reduced to a few days, and the number of engineering documents was reduced by 50%.

The reduction in spare parts inventory will result in future savings. BASF used to maintain thousands of dollars in spare parts to support the legacy DCS. The value of the DeltaV spare parts inventory is 90% less than that of the legacy DCS. As a result, future expansions will be less costly.

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