Kraton moves towards greater reliability in batch processing
Houston, TX - Kraton Corporation, a developer, manufacturer and marketer of pine chemicals and other bio-based chemicals and specialty polymers, has found that automating procedures with greater operator control and visibility can minimize human error, while improving quality and productivity
Kraton displaces petroleum dependence for equivalent products, but in so doing must account for the inherent variability in biomass feed stocks to their process. A large share of pulp and paper production in North America and Europe derives from pine trees in sustainably managed forests.
The company operates a North American and European manufacturing network of nine strategically-located facilities. But, at its Savannah, GA facility, too many out-of-spec batches were produced and required correction. The issue could not be pinpointed to a certain product or work shift. While the resulting off-spec product could be corrected, making the necessary adjustments took extra time, labor, material, and line capacity, which reduced productivity and profitability.
The previous automation system consisted of a series of programs that still required operator intervention at key junctures. After a review, the company determined that product quality could be significantly improved by optimizing the execution of manual tasks. Operators would get interrupted or busy with other tasks and natural human variability in operator response was also causing inconsistencies, for instance, in the starting and stopping of heaters and other time-sensitive procedural steps.
Kraton utilizes three different distributed control system (DCS) platforms to filter, centrifuge, and distill the feed stocks into resin precursors. To control their reactor processes, the company uses the D/3 DCS from Maryland-based NovaTech LLC process division, drawing upon its expertise in batch process automation, the flexibility of the sequence and batch language (SABL) that the D/3 controllers use, and for an S88-based layered batch management package called FlexBatch.
“I have not seen any DCS that can handle nearly as many loops and as much programming per controller as the D/3,” said Gregg Cox, senior controls engineer who designed the operator interface. “We run about 3000 I/O points on 5 Process Control Modules here, and we could probably do it on two.”
Later, Kraton added a layered procedural automation software package, paperless procedures (PLP), also from NovaTech, to the D/3. The software solution allowed manual tasks and automated tasks to be seamlessly integrated into the same SABL batch programs, an innovation which NovaTech patented.
PLP provides operators with an intuitive standard operating procedure-like checklist interface that merges manual and automated tasks in real time, that adapts dynamically to real-time process data, and which can be viewed from any PC, tablet, Smartphone or other device.
“The final product is completed with scheduled campaigns on FlexBatch that are completed with batches run with PLP,” said Cox. “This hybrid approach has improved product quality while reducing batch cycle times.”
With this approach, the operator can modify recipe parameters, recipe procedures, production schedule, batch start rules, equipment utilization, or scale batch amount at any point during recipe development and execution. Recipe values are automatically entered into the system, and all the operator needs to do is click on the reactor to use and which vessel to pull from. This is safer, more intuitive, and speeds the process because the operator selects all the equipment to be used before starting the procedure.
“This has resulted in batch cycles that are more consistently executed with the proper timing and procedure,” said Cox.
