Nothing could be more gratifying for plant personnel than helping output grow well beyond original design capacity — especially when product demand is strong. This is exactly what’s happened at Synthomer’s synthetic polymers plant in Kluang, Malaysia: in just three years reactor output has risen by more than 30% over nameplate rating.
The plant achieved this performance despite frequent alterations for product upgrades to meet competitive pressures. In addition, it still had to precisely follow batch formulas to match customer specifications or entire batches might have to be scrapped. Synthomer was able to establish its output record in large part because of shorter turnaround times between batches and batch-to-batch repeatability that’s more than 30% better than expected. We also have gained from substantial reductions in non-conforming and aborted batches.
Among the original design goals for the plant, which was commissioned in 2002, were high process reliability in responding to customer needs, flexibility, product consistency and batch traceability through accurate documentation. The plant couldn’t have attained any of these goals without Synthomer’s commitment to an advanced control system architecture, a batch-friendly automation system, smart field instrumentation and device management software capable of utilizing the intelligent devices’ self-diagnostics. It’s a small plant but our instrumentation is highly sophisticated.
Sophisticated Batch Control
The Kluang plant produces synthetic emulsion polymers, which are substitutes for natural latex and other products, used for surgical gloves or as additives in making cement, carpets, fabrics, etc. Petroleum derivatives such as butadiene and acrylonitrile serve as raw materials, so the plant is classified as a Zone 1 hazardous area.
The slightest process variability could affect the complex reactions of multiple components, leading to substandard and unacceptable final product. Because manual intervention causes inconsistencies, operators’ interactions with the reactors had to be minimized. The project designers knew advanced technology systems were essential to provide the necessary fully automated and highly sophisticated batch and recipe control.
After reviewing several alternatives, we chose to implement Foundation Fieldbus using Emerson’s PlantWeb digital plant architecture. This approach integrates all intelligent field devices, including digital valve controllers, transmitters and converters from various vendors, providing a fast, sure way of digitally communicating control input/output (I/O). In addition, it enables easy future integration of machinery health monitoring. The architecture greatly reduced the amount of field wiring required, thereby lowering construction time and costs.
We considered the DeltaV digital automation system to be the most “batch friendly.” It’s a system designed to do batch processing in reliable controllers, not one for continuous processing with batch software added as an afterthought. We also deemed it to have greater flexibility and better adaptability to changes and to be easiest to expand in the future.
With the batch schedules embedded and integrated into the DeltaV system, operators simply load a recipe, press “Start” and the process runs automatically until the batch is finished. Individuals only are involved in handling raw materials and finished products. They don’t interfere while a batch is in progress.