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.