By John H. Lewis, PE, Fulghum Industries
Fulghum Industries, Wadley, Ga., provides heavy-duty industrial machinery to the forest products industry. The company’s product line includes saws, chippers, loaders, conveyors, log handling cranes, drum debarkers, turnkey woodyards and chipmills, all designed to effectively transport and process wood into woodchips and usable wood fiber for manufacturing pulp and paper products, animal bedding and other goods. Fulghum also offers a variety of services, including consulting, engineering, construction and startup.
Fulghum was one of the first companies to implement remote wood-processing facilities, or woodyards, adjacent to paper mills and other customers’ facilities, and it has established operations of this type for major pulp and paper companies. Increasingly, in operating these woodyards, Fulghum has been asked to integrate its equipment into environments that include sophisticated wood-handling machinery, which very often have their own embedded control systems. At some woodyards, this machinery includes stacker-reclaimers manufactured by Bruks Rockwood, which recover and stack woodchips or wood waste fuel into stockpiles that can occupy up to 6 million ft3.
“Stacking and reclaiming stockpiles is one of the basics of materials handling,” says Fulghum’s Rob Powers, project manager for a woodyard system implementation in southern Georgia. Fulghum Fibres owns and operates multiple woodyards on-site at paper mills like this one. “Besides simply keeping the facility neater, safer and more organized, it speeds up processing and provisioning of this material to the customer, while reducing manpower requirements for facility operation and maintenance,” says Powers.
This particular installation has two Rockwood stacker-reclaimers, one for wood chips and one for wood waste fuel, or bark. Each stacker-reclaimer includes an Allen-Bradley control system that communicates via EtherNet/IP, an industrial application-layer protocol developed by Rockwell Automation and administered by the Open DeviceNet Vendors Assn. (ODVA).
The stacker is basically a belt conveyor on a crane boom that builds a kidney-shaped pile. The reclaimer’s design is similar to that of a giant chainsaw, with a massive boom that rotates and then rakes material from the stockpile to load onto a conveyor that feeds the paper mill (Figure 1). In the Rockwood machine’s case, the run signal originates from a DeltaV distributed control system at the pulp mill to signal chip demand.
Two Control Systems
Birmingham, Ala.-based system integrator Electric Machine Control programmed the reclaimer’s Allen-Bradley control system. Fulghum had responsibility for myriad other equipment at the woodyard—such as the cranes, debarkers and conveying systems it provides. “In this particular woodyard, the control system is all Opto 22,” explains Powers. “We have two large A-B RSLogix controllers on the big stackers and two A-B MicroLogix controllers on the truck dumpers. We have four Opto 22 Ethernet-based PACs for the woodyard chip and fuel systems. We used RSLogix as recently as four or five years ago. We’ve used everything from Modicon to Square D.
Improving operations at a woodyard where critical control processes are handled by hardware from multiple vendors proved challenging for Fulghum and its integrator partner, Advanced Control Solutions. The two companies had worked together on multiple large projects and were very happy with the performance of the Opto Snap PAC system, which manages the conveying systems that handle materials from our woodyard chipper and debarker, as well as from the truck dumpers. Fulghum also uses the Snap PAC system for monitoring chipper motors’ amperage, temperature, oil pressure and other conditions. They value the system for its distributed control architecture, easy programmability and reliability.
The stacker-reclaimer, meanwhile, remained inextricably dependent on its ControlLogix embedded control system.
Integrating the Systems
As time passed, however, the scope of operations at the woodyard expanded. Fulghum, ACS and Electric Machine Control had to respond to new control system performance requirements. As new processes were added or modified, newly added equipment and instrumentation needed to be switched, and operating conditions and equipment states needed to be monitored closely. In some cases, alarms needed to be established to warn when conditions or machine performance deviated out of specifications. “The paper mill asked for some direct digital passthrough to the belt-scale weights, process measurements and equipment status. The initial installation was discrete control,” explains Powers. “To shift our data from Ethernet to EtherNet/IP required us to install an additional Snap PAC to build the data registers. We used that as a firewall, so our data and their data remain separate, which keeps our response time on the network better. If all of their data is flooding our Ethernet system, it becomes noisy. And if we elect to go to automatic rate control on the stackers, that would be able to be done because of the change. We just haven’t decided to do that yet.”
ACS systems engineer Sean O’Rourke implemented and configured new Snap analog and digital I/O and controllers to add the needed functionality to communicate to the A-B stacker-reclaimers and to the paper mill’s DeltaV system. The native state of Opto is Ethernet, and the native state of A-B and DeltaV is EtherNet/IP. We had to add a special Opto PAC controller so we could have the interface.
“The additional functionality was added because the paper mill wanted to get real-time data—wherever they needed it—from us,” says Dustin Dixon, Fulghum Fibres’ mill electrician for the woodyard. “We’re sharing data back and forth. At the moment, we’re only receiving run requests and stop requests, but we’re sending them real-time data. The Opto 22 controller supports interfacing with A-B without a third-party box (Figure 2).”
Electric Machine Control customized and fine-tuned changes to the ControlLogix PLC and control programs. A primary project goal from the start was to interconnect the two control systems for data throughput and operational coordination. “We saved miles of discrete wiring by plugging in fiberoptic cables from one machine center to another,” says Powers. “We eliminated hundreds of discrete signals. That’s what the Opto 22 Ethernet system gave us. We also had to contend with the connection between the RSLogix systems—we’d sometimes have 200 variables. You wouldn’t want to do it serially.”
CONTROL OUTSIDE THE BOX
It was imperative for these two seemingly mismatched systems not only to coexist, but to communicate and share data.
We determined that the best way to accomplish this would be to maintain the local Opto 22 distributed system while using the plant-wide Ethernet TCP/IP network, primarily because of the cost/benefit issues of hardware, software and additional training costs.
Making It All Work
Opto 22 had recently added support for Allen-Bradley’s EtherNet/IP protocol, which provided a method for the Snap PAC system to communicate directly with the A-B PLC.
“Our new stand-alone and rack-mounted controllers, as well as our I/O, now support EtherNet/IP,” explains Opto 22 senior application engineer James Davis. “Controllers that already are deployed by customers like Fulghum can add this support through a free firmware download from our website. Once enabled, the controller can serve as a slave or adapter and integrate seamlessly with the ControlLogix hardware.”
O’Rourke upgraded the Opto PACs via the firmware download and worked with Electric Machine Control to connect to the A-B PLCs via fiberoptic connections that provided a reliable, high-bandwidth, long-distance physical medium with a high degree of noise immunity.
Reconciling two disparate control systems, each very powerful and having its own strengths, is becoming increasingly common for system integrators like ACS and Electric Machine Control because end users increasingly are looking for a broader variety of options as they build or modify their control systems.
Davis believes that, instead of being locked into the platform or products of a single vendor, many customers want more latitude and the ability to use best-of-class technologies and homogenize their systems with no hiccups or sacrifices in performance.
For Fulghum, implementation of the A-B/Opto 22 EtherNet/IP project was accomplished simply and easily and avoided lengthy software development time. “We did it in less than a day,” says Powers. “That was the communication between the Opto 22 network through the Snap PAC controller that was building the files and handshaking those over to the large stacker machines for data transfer and operating parameters. All we did was build registers and set up addresses.”
An Easy Integration
Training was done on-site during startup, and continuing education classes are offered to electricians and mill managers.
“Configuration and setup were simple,” says O’Rourke. “We only needed to define the assembly instances and assign inputs or outputs and then specify the number of bits for how long each instance was going to be.”
This configuration then was downloaded to the Opto 22 PAC, and all that remained was to configure the RSLogix software and define communication to the Snap PAC as a generic Ethernet module.
“We did consider four brands,” recalls Powers. “But in the end, the level of support we get from ACS and the cost of the system to implement were the deciding factors. We couldn’t just use A-B I/O, even though the reclaimer is ControlLogix and EtherNet/IP-enabled. The question is whether we would put in four separate processors or put in one and let it control everything. The critical functions are localized. With the Opto system, we have local PACs.”
The data is 90% discrete and digital. Fiberoptic interconnectivity allows for less noise and shorter wire lengths. “Our general rule of thumb is that our customers expect our projects to have payouts in fewer than three years, and we’re already well under that,” says Powers. “Our system probably saved money vs. a hardwired system on the first day. We started the first phase of this project in May 2008, and the second phase, which was just completed, began in July. The total project time from concept to startup was less than 12½ months.”
Fulghum is considering working with owners of pulp and paper mills where Fulghum has established its woodyards to extend the reach and capabilities of EtherNet/IP communication. Many of these customers use the ControlLogix platform for process control in their facilities and would likely find great value in being able to aggregate and combine operational data relating to their manufacturing and processing equipment with information from the woodyard.
John H. Lewis, PE, is vice president of engineering and construction, Fulghum Industries, Wadley, Ga. Learn more about the company at www.fulghum.com.
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