In the 1980s, McGean, a Cleveland-based specialty chemical manufacturer, installed a process control system to make recipe writing and batch preparation simpler and to help the operation earn International Standards Organization (ISO) 9002 certification. However, the system became obsolete several years later. The company then turned to ABB and its SYMPHONY Six distributed control system (DCS) to effectively manage its growing number of recipes.
McGean plant operators and recipe preparation personnel were comfortable with the old control system's logic sequence for recipe building and batch processing.
"It's very much like you or I would write a recipe," explains Bryan Shaffer, McGean Cleveland production manager. "Basically it is in a text form with straight-forward directions. There is no need to interface with another format to create commands."
Although the process control system initially was successful with users, the manufacturer decided not to update it. Purchasing spare parts became more challenging each year.
"Parts were not the only problem," says Mark Herbert, McGean Cleveland process engineer. "We also saw what else was on the market, and we wanted those benefits and features for our operation. Our early control system didn't have a graphical interface so we had to try to visualize what was happening in the process, whereas later control systems provide a multi-color graphic window on the process.'
The criteria for new system selection became clear:
It should mimic the old system's recipe creation and processing characteristics.
It should allow existing recipes to be migrated to the new software with a minimum of rework.
It should provide a graphic display "window on the process."
Its potential obsolescence would be addressed to ensure longevity.
McGean selected the compact SYMPHONY Six DCS from Wickliffe, Ohio-based ABB. The system is used widely in batch applications such as pharmaceutical preparation. The company decided the SYMPHONY Six system would be configured to handle approximately 1,100 I/O points at the McGean Cleveland operation and would be installed in the same control room that was occupied by the earlier control system.
Most of the process monitoring at McGean Cleveland takes place at satellite workstations such as this one, which are distributed throughout the plant near reactors and mixer tanks.
During a scheduled inventory break in 1999, the old system was removed and the new one installed. However, the old system's key attribute remained ," recipes could be entered in text form using ABB's batch management software. In addition, approximately 90 percent of the recipes were retrieved from the old system and migrated to the new one.
The new satellite workstations on the production floor were equipped with graphics depicting the process in action.
In addition to handling ongoing processes, the SYMPHONY Six provides several types of displays for production improvement. These include trend displays, spreadsheet displays, system status display, alarm review, event review and event Historian, among others. Depending on plant needs, the system can be expanded to include the control of additional production equipment.
Obsolescence also was addressed. The SYMPHONY Six architecture supports the functionality of later-generation components, plus ABB provides a service to migrate the system to an advanced platform.