Process Engineering: Batch control sets the standard

It has been nearly a decade since the Instrumentation, Systems and Automation Society (ISA) introduced S88, its first standard for batch control systems.  Its still integral in optimizing operations today.

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“Users can simulate their process using Batch Plus without making a big investment in materials or equipment,” he says.

Systems built around the S88 standard are more accepted in regulated industries, Wheeler says. He estimates that about half of Batch Plus users are specialty or fine chemicals producers, and the other half are pharmaceutical manufacturers.

The Batch Plus program allows the user to build recipes, and the Batch.21 historian supports 21 CFR Part 11 compliance needs. “Batch.21 collects data from control systems or other platforms and uses the same hierarchy as S88,” Wheeler says.

ABB’s Ruhe has been involved with the SP88 committee since shortly after its inception. He says that S88-aware systems can provide a seamless and complete integration of computer and control systems. If a control algorithm is changed in the control system, the recipe in the computer system can be automatically updated.

“With an integrated system, you don’t have the nightmare of managing multiple databases,” he says. “There are no data concordance issues since the data is entered once – the ‘single source of truth’.”

Much to gain, little to lose
Better control of any process will contribute to improved operations. Craig says one of the main operational benefits of the standard is reduced variation. “S88 makes processes more schedulable,” he says. “If the schedule is optimized, then you can make more product more predictably.” This could result in 10% to 15% more throughput, he estimates.

Leo Charpentier, Columbia, Md.-based product marketing director for NovaTech LLC, says the modularity of the software makes it easier for a supervisor or engineer to make process changes, including during the night shift. This can reduce downtime and emergency trips to the plant during the night. “The plant is less dependent on control engineers,” he says.

Charpentier, who has been a member of the SP88 committee since the beginning, says S88-aware products, such as NovaTech’s FlexBatch software, allow batch processors to run shorter cycle times. Since the recipes are automated, equipment can be used for the next step as soon as it is available. “This allows operators to spend time addressing problems, rather than closely monitoring the progress of the batch,” he says.

FlexBatch runs on a Windows-based system, and integrates with NovaTech’s D3 automation system. After users install the software, they go through a configuration step and can then build their application.

Eastman Chemical produces several batch intermediate chemicals at its Kingsport, Tenn., site, where it uses FlexBatch, says Mike Eads, systems technical associate. He says implementing the S88-aware software required about three man-years to build the applications (defining accurate operating procedures for making the chemicals, writing sequence and batch language (SABL) programs, and developing the Master Recipes).

Eads says the biggest benefit of the system is standardization. “Each batch is produced using a Master Recipe for each product embedded in FlexBatch,” he says. “The result is products that are made in the same manner batch after batch.” Eastman uses FlexBatch on two batch processing lines that produce a variety of products.

Although Eastman’s control system requires permission from operators to proceed to certain steps, about 75% of the process is now run by the software, providing reduced batch cycle times. Eads says operators have to give permission to perform certain operations where the DCS cannot determine the necessary information, such as a tank level, visual inspection of certain intermediate products, or steps that require action by an operator for safety reasons.

Bob Fink, Croydon, Pa.-based senior process control engineer for Rohm and Haas, says the company has been upgrading plants without recipe-level automation and those that have an older in-house legacy system to Emerson’s DeltaV Batch. Additionally, plants built in the past several years have the automation system. He says about a dozen sites now use the S88-aware system.

Fink says it took engineers about a year to build a library of modules that they now connect to create recipes. “You don’t need someone with control expertise,” he says. “A process engineer can develop or make changes to a recipe in the new system.”

Fink counts quality and productivity improvements among the benefits of a system based on S88 principles. Product quality is more consistent on a batch-to-batch basis, whereas the system can coordinate different operations at the same time. “The main benefit is the flexibility,” he says. “We can now make changes easily to a system that makes a lot of different products.”

“S88 recommends a modular approach to automation, but gives no guidance about how to go about it,” says Dave Chappell, section manager for Procter & Gamble (P&G), West Chester, Ohio. “It’s a high-level standard.”

Since a large number of P&G’s products are made by batch processing, it was important to develop a method to automate as many of its batch production systems as possible. Chappell says P&G licensed a recipe-management system and then developed an in-house automation approach that would direct a truly automated engineering process for the design and automation of the company’s batch processes. P&G then licensed this system to ATR Systems Inc., now known as Siempelkamp, Cambridge, Ontario, in 2001.

Andrew Weatherhead, manager of the batch and process systems group for Siempelkamp, says it began marketing P&G’s system as Batch.Objects in September 2003. The company provides automation systems to various industries, however the clients that operate in batch mode are mainly in the consumer-products and pharmaceutical sectors.

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