By Jim Montague, executive editor
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Tim Dunlap isnt a coffee-slinging barista, but he probably makes more Frappuccino than anyone else on Earthabout 13,500 gallons per day.
Thats because hes the engineering and maintenance manager at the Dairy Farmers of Americas (DFA) plant in Mechanicsburg, Pa., which brews, blends and bottles Starbucks-licensed coffee drinks for distribution by Pepsi USA throughout the eastern U.S. To keep up with demand, Dunlap says the plant underwent a major expansion two years ago, from 600 bottles per minute on one glass line to 1,400 bottles per minute on two lines.
Wed always been automated with PLCs, but we knew we couldnt double our production with the proprietary controls, ActiveX screens and jumper panels we had before, says Dunlap. So we put a team together with the plants staff, our system integrator, GES Technology, and DFAs Dairy Systems to install an 800-bottle-per-minute glass line. The new line uses Rockwell Automations RS View and some ISA 88 integration, which was very standardized and easier to add onto. This allowed us to change code and modify screens as needed. GES had to write some code at the beginning, but now we can select among automated flow path changes.
To change products, we used to have to make both mechanical and software changes. Now, we only have to make software changes. ISA 88 and RS View also verify critical time and temperature on the lines and help us document performance too. Even adding new flavors in the future wont be a big capital expense.
So, everybody loves batch, and its not because theyre all getting cookies, cupcakes or Frappuccino. The 12-year-old ISA-88 batch standard and its revisions have pretty much solidified its position in the process control world, and now potential users increasingly are calling on suppliers to include it in their solutions.
ISA-88 has matured to the point that its going through revisions to comply with ISA-95, says Tim Stout, process systems department manager for Matrix Technologies, a CSIA-certified system integrator in Maumee, Ohio. The standard is widely accepted enough now that customers are talking about it and want to use it, so vendors are providing platforms, toolkits and software for them. Weve written a lot of ISA-88 concept software, and the tools just keep getting better, which means its also easier for us to put together projects with these controls. Standard batch functions and tools are becoming the glue that everything else attaches to. At this years World Batch Forum meeting, we learned that batch concepts are being applied to continuous processes and at the packaging level. Batch is even standardizing relationships between process, control and IT people because it gives them all a common language.
Why It Works
Batch is different than process control in how its set up and programmed. Batch lends itself to a more modular software design, so if you create the right blocks, you can rearrange them for different applications, says Hunter Vegas, of Avid Solutions Inc., a system integrator based in Winston Salem, N.C. If you do it right, you can save lots of time and money because the same piece of code can be applied to all three reactors in an application, instead of having to rewrite code for each phase in a recipe.
Source: Applying S88, Batch Control from a Users Perspective by Jim Parshall and Larry Lamb, ISA, publisher.
Similar to any process control initiative, a batch projects organizers and developers also must evaluate the overall business goals served by their application, assess what equipment their existing facility already has and decide what it will need for their plan to succeed.
Basically, continuous processes typically run without stopping, while batches are turned on and off. Distributed control systems (DCS) typically scan every 200-500 milliseconds, while batches need scan times of 100-200 milliseconds, according to Kam Yuen, product manager for GE Fanucs Proficy batch execution system. He adds that GE Fanucs new Proficy Process System combines these DCS- and PLC-based capabilities, and can use modular, reusable software function blocks to create batch sequences and set up phases more easily.
Theres a big difference between even a simple batch program that can be hard-coded into a PLC and a complex batch system that needs to handle 30 to 40 different products and doesnt have a fixed path. Users must think of all their applications stop scenarios and plan for all their contingencies, says Todd Stauffer, Siemens Energy & Automations Simatic PCS 7 marketing manager. These days, many users want to do both simple and complex, and they want to use the same software to do it. Luckily, ISA-88 and its extended definitions describe how developers should organize their software code. (Figure 1)