The yoga of batch
Building strong and flexible plants.
By Ellen Fussell
Strengthening communication, building flexibility into processes, controlling procedures in a continuous process, and ensuring compliance to new standards—these are the burning issues batch manufacturing companies are facing. Automation gurus are coming to the rescue with systems to accommodate these needs, stretching the limits of traditional batch processing and helping companies gain new perspectives and ultimately improve their businesses.
Using the term “batch” might make some industries cringe—industries such as pulp and paper manufacturers that depend on continuous processes, said Mike Heatherman, product manager for batch at ABB in Wickliffe, Ohio. “But we see a lot of benefits from batch that can apply to more than batch processes,” he said.
“Manufacturers of polymers, pulp and paper, and textiles have to mix dyes together. It’s basically a chemical process. We’re trying to help people understand they can apply our batch system to these other applications,” Heatherman said. “Even in a continuous plant producing lubricants or polymers, where they have a plant set up to run continuously, they’ll need to change product—add a different grade of polymer,” he said. The plant won’t want to shut down during the procedure.
During the transition, it’s making off-spec product (the period of time during production that doesn’t meet specs). The plant might be making one grade of polymer, increasing temperature or changing pressure. “Until they get all the set points lined up to make the new product, they want to minimize that amount of time,” Heatherman said. That’s where applications for procedural control come in.
Heatherman’s team also supports collapsing and ex panding the procedure model for ISA-88, which adds flexibility to a manufacturer’s procedure and involves four levels: recipe procedure, unit procedure, operation, and phase (the lowest level). Expanding means adding a level to the procedure, while collapsing means subtracting a level or simplifying a procedure.
“Collapsing means you don’t have to configure all those different levels,” he said. “Each level [procedure function chart in a screen window] is work an engineer creates. So if you have a simple procedure, you don’t want to configure all those extra levels if you don’t need them; it saves engineering time.”
It also saves the operator time. When an operator schedules a batch, run-time displays show the operator what the procedure is doing. Procedure levels generate those views, making the procedure simpler for the operator interface. “In complex batch manufacturing—say, bulk pharmaceutical—you need those different levels, or flexibility,” Heather man said.
Phase (the lowest level) changes set points and opens valves and motors. The operation level might involve distillation or heating or running multiple phases in sequence of parallel. “So you’d have a phase that could charge or start the agitator,” he said.
Unit procedure involves a reactor or tank—actually mixing and heating. “It’s running the sequence of operations to perform a step of making the product, taking you through that step by step,” he said.
The highest level is recipe procedure. “To make a product, you’re performing multiple steps in multiple pieces of equipment,” Heatherman said. “So in tanks, reactors, or distillation columns, you’re combining chemicals and chemical reaction and transferring that material to the next unit, so the recipe procedure is coordinating across equipment.”
While the model that connects equipment isn’t new—it’s the ISA-88 standard—Heather man applies the concepts to other procedural control applications, such as making polymers, making grade transition from one grade of product to the next. “The places the procedure can be applied is what we’re promoting. It’s been done, but not in a big way,” he said.
In the batch control automation system, controllers do the real-time control connecting to I/O blocks wired to actual valves and motors. Then a workstation or server level lets them engineer the procedure into the system. “So every time they want to do one of these, they can do it consistently. There’s a basic premise that you can’t optimize anything until you can make it consistent,” Heatherman said. So procedural control is the first step to get to a consistent operation.
“The system is made up of servers with different functions and controllers. There are operators that would use the system to operate their process, so this would provide them a view of what’s going on. Alarms call their attention to abnormalities or exceptions,” Heatherman said. “It collects data for reports of how the product was actually made and provides levels of safety with interlocking to make sure they don’t overflow tanks or burn motors. So it protects people and provides repeatable and consistent production.”
How manufacturers use XML
Previously, manufacturing customers required custom coding. But now, with a standard product offering, there are more interfaces where XML points can be integrated together, and that means more integration capacity.
“Were adding recipe structures and equipment models via XML and standardizing how people can integrate batch processes. If they just want batch or MES, we have that,” said Pamela Mars, Honeywell’s batch product manager.
Mars said Honeywell is building standards integration using XML to help customers get all their information pulled into their MES system, so they’ll have all their genealogy pulled together for compliance needs.
“In the big picture, it’s getting the right information to the right people,” she said. “So if you can get all your material usage into your inventory system quickly, then you can make better business decisions.”
Complying with the 21 CFR Part 11 standard is the burning issue in batch for Bob Babecki, Foxboro’s product manager in Foxborough, Mass. “There’s still a misconception in the industry about what compliance means,” he said. “People talk in terms of their product being compliant, but the government doesn’t certify products as compliant. It’s the end users’ installation that consists of the process control procedures in making the product. The FDA will never tell him he’s compliant; they’ll just tell him when he’s not compliant.”
If a pharmaceutical manufacturer’s procedures were under Food and Drug Adminis tration (FDA) inspection, “they could say you’re not in compliance because operators are able to switch from one function to another, or you’re able to have an operator take over and not identify himself,” Babecki said.
That’s why the compliance issue of the electronic signature is so important: to know who did what when. It’s not that a manufacturer wouldn’t have the electronic signature procedure in place, but the operations personnel might not be trained and might not follow the procedure or be aware of it, Babecki said.
“When you configure a procedure, you can identify groups of personnel who have access to certain functions. In order to be able to carry out a function, you’d have to be part of the authorized group,” Babecki said. “You could have some highly sensitive functions that require a second electronic signature, like a supervisor, so the system would check to make sure the user is a member of the authorized group. Their signature, password management, and rules about password aging and reuse are all in our software.”
RESOLVING NEW ISSUES
New trends in the batch industry involve standardization of the interface between production management software and business systems. The ISA SP95 committee, in conjunction with World Batch Forum (WBF), has established a set of schemas that uses extensible markup language (XML), the technology behind most of the Internet (see related story on SP95 in the plant, page 38, and the sidebar on XML above). It’s a newer method of standardizing communication between business planning systems and manufacturing systems and is designed to allow two systems to communicate easily.
Business planning systems may be handling production planning—accepting orders from customers and setting up a schedule so the factory can produce a product quantity by a certain date. As part of planning, the schema helps manufacturers communicate when the production is completed and how much of each raw material was consumed in producing that product. The WBF has published its XML schema, so batch software manufacturers now have a standard to produce products.
The enterprise resource planning (ERP) system lets you create a schedule. Then, using these XML schemas, it could pass off instructions to the batch engine to make it. When the batch engine is finished, it tells the ERP system what quantities of each material it used. The system performs an activity-based costing.
“So rather than calculating it for a facility at the end of the month, you want to know on an activity-by-activity basis what the cost was,” Babecki said. “If you’re doing analysis of what it cost to serve a particular customer, you might look at that customer’s orders and be able to tell what it cost to produce each of those.”
For example, a specialty chemical manufacturer took about 24 hours to make a batch. It installed the batch engine and cut its batch cycle time from 24 to 12 hours. “When making a batch, the manufacturer had a number of steps to go through, but by automating these steps, they could do them as fast as the equipment would permit them. So they weren’t waiting on the operator to notice, to say it’s OK to go to the next step,” Babecki said.
The magic is in the way the batch engine handles connections and transfer of material among units. The software manages and makes the logic down in the controller that it’s supervising much simpler to write. Thus, the system is easier to maintain, Babecki said. Doing this after each batch results in tighter integration, which leads to better information and faster, more effective decisions.
Users today are looking for flexible solutions, said Pamela Mars, Honeywell’s batch product manager. They want to start with batch control and add manufacturing execution systems (MESs) and ERP integrated together, Mars said. “They want a fully integrated solution, so they might be starting out with a control system in batch applications and building on top of that with all the building blocks you need for process,” she said.
The key to flexibility is having standard interfaces that are flexible so customers don’t have to do configuration. It’s typical to have the capabilities, but it requires custom coding and building custom interfaces. “Customers need standard interfaces using standard accepted technology like XML and leveraging that across the system,” Mars said.
One piece of the puzzle could involve environmental controls to avoid contamination. “That’s especially critical in biotechnology and pharmaceutical industries,” Mars said. Con trolling temperature or tracking when doors open and close is important to avoid introducing contamination into a product. “You might want a video of who walked in and what they did,” Mars said.
ORGANIZING WITH MES
Some of the key components for MES are material genealogy, lot tracing, and order management.
“For a regulated environment, you may need full material genealogy”—being able to track material from start to end point, Mars said. “Say you have a tank of material and need to use 50 pounds of this in preweigh. You feed the material into one of the batches, and that material gets distributed to two more batches. So you need to trace what’s in the material to all the raw material components,” she said.
“As your batch is executing, you’ll want to track all the materials you’re using and feed into the ERP system, your inventory management. Then your XML schema [how the data is laid out] comes into play because two people can talk the same language. So you don’t have to have a custom interface. You can use the same format, everyone talking in a standard XML format. You don’t have to do the custom work to make the systems communicate to one another.” IT
What does 21 CFR Part 11 cover?
What process data falls under the guidelines of 21 CFR Part 11? An FDA summary issued criteria by which it’ll accept electronic records, electronic signatures, and handwritten signatures. These regulations apply to all FDA program areas to permit the widest possible use of electronic technology, said Total Systems Design, Inc.’s Neal D. Collier and G. Duane Grob in their paper, “Computer Validation as it Pertains to 21 CFR Part 11,” presented at ISA 2002 in Chicago.
What the summary is saying is that if the FDA requires a company to keep specific batch records for submission and archival purposes, and if a company chooses to keep those records electronically, then 21 CFR Part 11 applies to those batch records. Parts 210 and 211 provide guidelines for FDA record and signature requirements. If a pharmaceutical company has record and signature requirements set forth in those two sections, and it can meet the requirements of the standard, the company can use electronic signatures and records. There are many data records to store, and data can come from different sources and is stored for different reasons. The actual process database could be one large database or several smaller ones.
Process data includes flow, temperature, and level. You create alarms and events at the supervisory control and data acquisition (SCADA) node and push them to a custom relational database. While it’s true you can configure alarms in data sources such as programmable logic controllers and distributed control systems, today’s SCADA software has preprogrammed, industry-standard alarming schemes and screens.
Examples of SCADA-logged events are loss of power, system log-ins and log-offs, and redundant switchovers. You should also tie alarms and events to a logged-on operator. When an alarm comes in, the system must record who was logged on at the time. Any operator actions must be traceable.
Examples of batch-specific information are batch ID, start time, stop time, and end-of-process weight. The batch-specific portion of the process database contains information you must modify between the beginning of the process batch and the end—stop time is an example. Of course, you know the start time at the beginning of a process batch, but not the stop time, so you enter it into the database records as a zero value. When the batch stops, you change the database to the actual value.
Before you start a process, you must select a recipe for the process batch so the process control equipment can safely make the product. The standard says you must store all recipes in a secure central location. Although it’s possible to store recipes in the same computer in which you store the process database, you probably shouldn’t because managing the process database should be that computer’s primary task.
Of course, you must track any changes to the process recipe, which should result in a new recipe version. If you don’t use the new versions, keep an audit trail. You also need a recipe archive database so the recipe manager can access previous recipes.
Section 11.10 covers controls for closed systems that limit access to authorized individuals. It says the security system should include these elements: