Tech Update: Advanced Process Control
Advances in controls technology often manifest themselves in their ability to make the possible more probable.
Call it the Mies van der Rohe effect: Refinements in the tools of process control often mean a less-is-more approach to automation.
Instead of multiple data networks, a single communications system can serve a plant’s needs. Rather than tedious coding exercises, object-based libraries are filling the programming role. And the protracted integration work for shop floor systems is giving way to faster, less painful and more economical projects.
Consider, for example, process analytical technology (PAT). Food and beverage companies are in the toe-dipping stages of PAT implementation, though New Zealand’s Fonterra dairy cooperative has begun applying PAT to infant formula and cheese production. The FDA strongly encourages pharmaceutical manufacturers to adopt PAT, advising them that “quality cannot be tested into products; it should be built in or should be by design.” Given the minute levels of active ingredients in drugs, strict validation and control of the manufacturing process are critical for human health.
Similar criticality doesn’t exist with food. If too much syrup is blended into a soft drink, Brix will be off but no one will die. Manufacturers’ processes must deliver the ingredient amounts promised, and that performance is validated with downstream testing. To minimize scrap and deal with process variation, a fudge factor is built in: If the product promises 10 grams of an ingredient, the process set point might be 10.5g.
Of course, 5 percent giveaway is a big deal when millions of units are manufactured, and one advantage of PAT is the enhanced precision it provides in hitting the set point and avoiding out-of-spec finished goods. Glenview, IL-based SensiBlend uses PAT in its inline mixing system. SensiBlend Vice President Matt Glicken has spent the last year demonstrating the advantages of PAT and inline mixing to his former associates in the carbonated beverage business. Eliminating mixing tanks and offline quality testing from the process are clear advantages, Glicken points out, though reduced waste from out-of-spec finished goods also is appealing.
A controls upgrade at Bama Companies last year provides another example of the beauty of simplicity. The Tulsa, OK baking company operates three plants, including a frozen-dough facility equipped with 1995-vintage PLCs. Pizza dough and other products are comanufactured for multiple customers, and 15 years of recipe changes and customized programming created a legacy platform that required constant tending by skilled personnel. Unreliable electrical service magnified problems: “Just a 30-second voltage sag was enough to take valves and other devices out of sequence,” explains Sean Nichols, controls engineering lead, resulting in up to seven hours of downtime. More robust, standards-based controls were needed, and Bama managers selected S88 batch programming and Allen-Bradley technology such as RSView 32 HMIs for the upgrade. “S88 is a standard solution that allows you to break the process down into logical pieces that make sense to a process engineer and can be implemented by an automation engineer,” according to Ben Mansfield, marketing manager for Rockwell Automation’s PlantPax, a process automation solution that straddles the worlds of PLC and DCS.
Recovery from brownouts now takes minutes instead of hours, and recipe management is streamlined and standardized. Ladder logic reprogramming is a thing of the past, as are the mapping and tagging of field devices. Ethernet IP connects valves and instruments to machinery, making DeviceNet redundant. “Whenever you shake out every device in a plant, you’re going to find a lot of gremlins,” Nichols observes, and that was the case in Tulsa: Valves that were never reconnected to the data network after servicing were uncovered when the new architecture was simulated in August. Now, the status of every device is apparent on the factory dashboard.
“It ended up being quite a bit more expensive than originally planned,” Nichols conceded in a presentation at Rockwell’s Automation Fair in November. Nonetheless, the simplification of managing and maintaining the system “saves us a ton of money.”
OEMs as tech providers
Few developments illustrate the improved accessibility and reduced complexity in controls technology like the extension of machine control into line integration and even higher-level information systems. Instead of delivering a filler and letting the manufacturer deal with coding issues, equipment OEMs are offering food companies the opportunity to leverage preloaded, object-oriented control code for interrelated machinery. Some of those control packages are based on an open, component-based process control system called Plant Direct iT from ProLeit AG, a German technology firm.
An example is ITM-Plant iT from Heat and Control Inc., Hayward, CA. Instead of requiring end-users to layer MES solutions on top of control systems to extract OEE metrics, track-and-trace information and other data, ITM-Plant iT short-circuits software maintenance costs and startup challenges with its object-oriented model of predefined code. Bettermade Snack Foods in Detroit deployed ITM-Plant iT when it added a four-position, on-machine seasoning application and packaging system. Those positions are treated as modules; operators have visibility to the performance of each module from a single control point.
“It’s a game changer,” insists Paul Nowicki, Heat and Control’s global information/simulation engineer. “This is an MES and control database that lets you see what’s going on with all the line components. It’s not shoving records into the PLC and hoping it controls the line.” The ITM in the name stands for “information that matters.”
Built into the system is a function called Visu Recorder, a remote diagnostics and troubleshooting tool. “Visu Recorder captures everything going on in the controller over time,” Nowicki explains. In the event of an upset, past sequences can be replayed, aiding technicians in their diagnosis.
Plant Direct iT also is the foundation for Brew Max, Krones Inc.’s advanced control package for liquid filling lines. Tetra Pak is introducing a system called iLine XT that integrates palletizers, printers, labelers and other packaging line components all the way to the ERP level. Tetra Pak did not respond directly to a question about the basis of its control platform, but Brighenti Massimo, program manager, iLine XT, wrote, “Our solution is based on industry standard modules and protocols programmed into our own solution,” adding Tetra Pack’s automation solutions “are based on globally available software and hardware with some special Tetra Pak additions to fulfill” food production needs.
OEM’s expanding role in controls technology is not the only pressure being exerted on mainstream providers of food automation technology. Companies that traditionally served automotive and other industries are shifting their focus to food and beverage production. Consequently, open standards and vendor-neutral components are getting a boost, enabling manufacturers to select best-in-class solutions that pose fewer integration challenges.
Global industrial controls sales at Mitsubishi Electric Automation Inc. rival Siemens’, but food automation has been a tiny sliver. David C. Kaley joined the firm in late 2010 to help raise its profile in food and beverage, and the Vernon Hills, IL-based business development manager believes both food packaging and processing machinery can benefit from the combination of sequential control, motion control and robotic control possible with Mitsubishi’s PLCs.
“Most of today’s PLCs can handle motion applications, as long as the motion is slow,” says Kaley. Mitsubishi’s technology is different, he maintains, in part because it is engineered to work with servos. “The packaging industry is where motion control really stepped up,” he says, and successful implementations with high-speed vertical form/fill/seal machines bode well for expanded applications.
Speed is not the only benefit of the newest generation of controllers, however. Energy and condition monitoring can be easily and cost-effectively added to the controller rack. This represents a sea change in the state of technology from a decade ago, when energy monitoring involved bulky, expensive units that required highly skilled specialists to use. With shorter production runs and more frequent changeovers becoming the norm in food production, Kaley believes these enhancements will become critical for preventive maintenance and uptime analysis.
Faster operating speed also is promised by Beckhoff Automation GmbH, which bases motion control on the PC. Machine speed is “a thousand times faster with PC-based automation than with standard PLC automation,” maintains Christian Schulze, senior business development manager for the German automation firm, which has its US headquarters in Burnsville, MN. He cites the company’s success in improving performance of cigarette packaging machines. By swapping out a multi-panel industrial PLC for a single PC and cabinet, machine speeds increased 20 percent, from 6,000 cigarettes per minute to 7,200. The PC technology also came at a significantly lower cost, according to Schulze.
Fresh from his triumph in tobacco packaging, Schulze is training his sights on a much larger industrial segment: food and beverage. As part of the initiative, the firm is introducing components such as a stainless steel servo motor.
Old guard, new tricks
Cognizant of the hot breath of competition, automation companies with an established presence in food and beverage are introducing their own innovations in controls technology. An example is Knightdale, NC-based Schneider Electric USA Inc.’s EcoStruxure suite, which elevates energy management to the same level as machine performance, asset utilization and process data.
The point of any control system is to provide a clear picture of what is happening in the production process, including energy efficiency, according to Robb Dussault, manager of the PlantStruxure process automation component of EcoStruxure. The conventional approach to process automation, device management, Historian and energy management has been to view them in isolation. That creates a siloed approach that is difficult to engineer and maintain, says Dussault. In the case of energy use, a context for consumption is absent. With PlantStruxure, Schneider is providing an energy management dashboard that puts consumption into a production context.
Intelligent motor control, along with energy management and device management, is the foundation of Schneider’s efforts to go beyond electric distribution and machine control into more advanced information systems. Smart motor control centers also are being addressed by Siemens Corp. Instead of simply protecting motor controls, smart technology answers the question of why an overload relay tripped, says Jeff Woolfolk, target market consultant for low-voltage motor control centers, Atlanta.
Five wires per motor in a control center are typical, and an “anaconda” of wire is quickly created as motors are added. If smart control meant additional wiring, Woolfolk doubts engineers would embrace the concept. Instead, Siemens’ solution is based on SiMoCode, shorthand for Serious Motor Control Device. “It’s a little PLC,” Woolfolk explains, “with expandable, modular applications for motor control.” Continuous monitoring of motor load coupled with the PLC’s computing power provides plant operations with multiple options for dealing with voltage drops and the consequences of mechanical failure, he concludes.
Technical solutions like SiMoCode and energy dashboards have been possible in the past, but they were much more difficult to implement and maintain. With controls engineers in short supply and high demand, manufacturers need technology that simplifies the number crunching and analysis at the heart of improved performance. That is the need automation firms are endeavoring to address with advanced controls.
For more information:
Christian Schulze, Beckhoff Automation GmbH, 49 5246 963-193, firstname.lastname@example.org
Ola Wesstrom, Endress+Hauser Inc., 317-535-2134, email@example.com
Paul Nowicki, Heat and Control Inc., 919-780-7855, firstname.lastname@example.org
David Kaley, Mitsubishi Electric, 847-478-2213, email@example.com
Ben Mansfield, Rockwell Automation Inc., 440-646-5000
Robb Dussault, Schneider Electric USA Inc., 978-975-9679, firstname.lastname@example.org
Matt Glicken, SensiBlend, 855-494-3423, email@example.com
Jeff Woolfolk, Siemens Industry Inc., 770-625-5760, firstname.lastname@example.org
|An IT-engineering armistice|
An uneasy truce usually exists between controls engineers and IT personnel, though open warfare is always a possibility as organizations push ahead with efforts to integrate the shop floor with the top floor. Often that entails integration with plant floor controls, and few events raise a plant engineer’s hackles like the potential process upsets that can result.
One way to defuse tensions and meet the needs of inventory management, IT and corporate management is to create a shadow system of sensors, meters and other devices that takes advantage of wireless communications, suggests Ola Wesstrom, senior industry manager-food & beverage for Endress+Hauser, Greenwood, IN. Alternatively, existing field devices could do double duty, feeding analog signals to process controls and digital information to the shadow system. “Close to 90 percent of devices today are HART capable,” notes Wesstrom, referring to the digital communications protocol more formally known as Highway Addressable Remote Transducer.
Leveraging HART for deployment of advanced process automation systems is appealing to firms such as Rockwell Automation, says Ben Mansfield, marketing manager, PlantPax. Deployment of PlantPax at Bama Companies would have been more complicated and costly if field devices had to be replaced, but that wasn’t the case, thanks to HART. “You can change the brains and leave the end devices in place if the installed base is intelligent,” Mansfield points out.
Whether a manufacturer opts for wireless HART or uses the protocol in conjunction with Ethernet IP, Wesstrom says there is untapped potential in collaborative communications to ease tensions and simplify tasks such as device configuration. Regarding Ethernet IP, “IT people recognize it and understand how it works,” he says, and it is becoming the communications highway of choice in food plants. The potential for enhanced monitoring at a reduced cost should appeal to CFOs as well as process engineers.