DCS/PLC System Simultaneously Upgrades Plant, Cuts Costs

To do more with less is not an easy challenge. Luckily, some timely assistance is exactly what engineers at Engelhard Corp. (Attapulgus, Ga.) received recently when they sought to replace outdated control systems and reduce overall costs at their petroleum catalysts production plant.Engelhard's staff was working to cut costs by $7 million per year, but also knew they had to replace the pl...

03/01/1998


To do more with less is not an easy challenge. Luckily, some timely assistance is exactly what engineers at Engelhard Corp. (Attapulgus, Ga.) received recently when they sought to replace outdated control systems and reduce overall costs at their petroleum catalysts production plant.

Engelhard's staff was working to cut costs by $7 million per year, but also knew they had to replace the plant's obsolete control systems, which were in increasing danger of failing. Engelhard also had 13 control rooms throughout the plant. It's automation consisted of various loosely connected PLCs with eight different human-machine interfaces (HMIs) and several single- and multiple-loop controllers. All of these collected information separately and presented it in different formats.

Faced with a potentially costly upgrade, Engelhard's engineers projected that centralizing operations and using innovative control technology might lower operating and maintenance costs.

To accomplish these tasks, as well as consolidate process control data collection and presentation, Engelhard's engineers eventually selected an APACS process control system from Moore Products (Spring House, Pa.) for control and an InTouch operator interface from Wonderware Corp. (Irvine, Calif.) for monitoring. Engelhard's new Microsoft Windows-based system is a seamless network of over 1,000 I/O points, main and satellite control rooms (with eight and two operator stations respectively), two engineering workstations, 25 PLCs, and a variety of transmitters.

The APACS unified DCS/PLC system has an integrated set of tools for controller configuration. Based on the IEC 1131-3 standard, APACS provides four PLC programming languages that can be used and combined as needed within a single database. These languages include: function blocks, ladder logic, sequential function chart, and structured text. Engelhard's engineers say a primary reason they picked APACS is because its graphical format was easy to learn.

APACS' ability to combine four languages in one control strategy slashed Engelhard's configuration design time. When creating functions, for example, engineers substituted up to eight rungs of ladder logic with one function block. The software's cut, copy, and paste abilities also allowed engineers to duplicate and replace redundant strategies as needed to control interlocking requirements on the plant's transporter diverter valves.

Engelhard's combined APACS and InTouch system and its graphical form helped the engineers view their configuration on-line. "We can actually see what's going on and force values within the control strategy, which really helps in troubleshooting the configuration. Before APACS, we really couldn't access this information at all," says Buster Terry, one of Engelhard's instrument technicians.

InTouch's development tools—such as object-oriented graphics, animation links, distributed alarming, and Wizards library of preconfigured objects—further reduced typing time, and this helped engineers create operator screens more efficiently. Training new users was also easier because Engelhard now had one plantwide HMI.

Engelhard's engineers also reported an unexpected bonus. Implementing APACS and InTouch didn't require any unscheduled downtime. And, as they hoped, the new control system has already reduced maintenance costs because errors and field failures are much easier to pinpoint. Engelhard's future plans include setting up an enterprise resource planning system that can run Microsoft Windows NT and communicate with the control system, as well as adding Internet functionality later.

For more information, visit www.controleng.com/info





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