“Change is the only constant in life,” according to Heraclitus, a Greek philosopher. Agile systems enable future change not anticipated by the solution architect. The ISA-88 standard prescribes agile systems. Agile recipe development and management allows manufacturers to take advantage of opportunities and react quickly to external threats, positively affecting profits. Agility in process cell cleaning practices can similarly affect profits.
The heart of agile cleaning is an ISA-88 batch management package, where cleaning requirements can be defined in one or more recipes rather than in control programming and data tables. Here, we find the first advantage. A process-knowledgeable person can modify the cleaning practices without hiring or being a controller programmer. Modifying an ISA-88 flowchart-style recipes is easy to learn and do well in comparison to controller programming.
Efficient cleaning is doing the right kind of cleaning based on the product made and equipment status. Hard work, enabled by agile tools, can make a dramatic difference. One client increased process cell capacity by 20% through careful experimenting, swabbing, testing, and adjusting of their cleaning recipes—all without our help or knowledge. Because we exposed the capabilities of the equipment, they were able to modify the recipe to attempt cleaning the equipment in parallel, adjust times monitor various conditions and the like. The capacity to make 20% more product, with no incremental equipment cost and minimal marginal labor cost, increases plant profitability dramatically.
Another advantage comes from using the system campaign manager to schedule the right cleaning recipe between product campaigns automatically. Not all products require the same level of cleaning. Some may require significantly less. A campaign manager can automatically schedule a cleaning recipe, that is designed specifically for the cleaning requirements of that product. When compared to using a single, worst-case scenario, cleaning recipe following all product runs, intelligently doing the right cleaning increases available process cell capacity, and plant profits.
Using a batch management package for cleaning recipes provides an electronic record of said cleaning. Such records can be used in a variety of ways to improve cleaning practices and identify cleaning. Building from the previous example, a monitoring system can validate from the electronic record that the right cleaning recipe was executed and completed without anomalies. Admittedly, lowered risks only effects plant profitability indirectly, but is certainly valuable to business overall.
Cleaning can gain agility through exploitation of a little-used ISA-88 requirement that equipment modules—teams of equipment working together to perform a process task—can coordinate other equipment modules. Cleaning is more agile when a coordinating equipment module synchronizes four cleaning equipment modules—the cleaning system supply and return and the process supply and return. Corresponding cleaning phases in the batch-area model enables recipes to couple the process unit cleaning stages with a cleaning supply and return at run time.
This agile approach was used on a 60-unit process cell initially designed so that any unit might be cleaned by any of three cleaning systems. After being in production for some months, the client recognized the value of investing in a fourth cleaning system, allowing parallel cleaning of four units instead of three. This change could be supported in approximately one day of engineering time, with essentially no startup, and as new supply and return equipment modules were added with a fourth coordinator capable of using the existing 60 process supply and 60 process return equipment modules. The additional cleaning system improved the process cell overall effectiveness, increasing cell capacity and improving plant profitability.
These examples apply to both cleaning in place and cleaning out of place practices. Recipe-procedures in a batch management package can easily direct operators to perform manual actions.
Implementing agile ISA-88 system for batch process control and cleaning can cost 10% to 20% more initially. However, the investment can easily pay large dividends over the life cycle of the project.
Timothy S. Matheny, P.E., is president of ECS Solutions, a certified member of the Control System Integrators Association (CSIA). He is also author of a paper on model-based control, presented to the ISA Food and Pharmaceutical Industry Division in 2014. To obtain a copy of Matheny’s paper, or for more information about ECS Solutions, visit its profile on the CSIA Industrial Automation Exchange.
