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THE INDUSTRY WORKHORSE: Roller assemblies consist of a roll pin, two roller bearings and roller shell. Prolonging the lifespan of each of these components must be the focus of a sound operations and maintenance (O&M) program. PHOTO: ANDRITZ
BEARING DOWN Producers seeking to drive down overall operating expenses must find ways to prolong roller and roller bearing life. BY TIM PORTZ
18 BIOMASS MAGAZINE | JANUARY 2017
elletizing woody biomass is hard on equipment. This reality is widely accepted by pellet producers, pellet press manufacturers and lubricant providers. The friction and heat generated inside an operating pellet press begin wearing down dies, roller shells, roller bearings and roll pins almost immediately. While the average lifespan of these wear parts varies from plant to plant, their replacement and refurbishment represent a significant portion of producer operations and maintenance (O&M) budgets across the industry. A roller assembly is made up of a number of parts, including a roller shell, a roll pin, a number of seals and O-rings and roller bearings. One roller assembly has two bearings, each with a price tag of nearly $500. With two, and sometimes three roller assemblies in each press, producers have thousands of dollars’ worth of bearings installed in each press. “Roll bearings are the single biggest issue in any pellet plant,” says Jase Locke, an aftermarket account manager at Andritz. “Everyone who has a pellet press is trying to figure out how to prolong that roll bearing life.” Roller bearings, Locke explains, enable the roller shell to turn around the roll pin. The friction generated at the intersection of the pellet die and the roller shell is transferred to the bearing, protecting even more expensive components like the roll pin from early failure. As the industry matures and grows, best practices for prolonging the lifetime of these wear parts have begun to emerge, and producers are putting a number of different approaches to work, calling upon press manufacturers and other players for more. “What we are seeing today in the industry are these new, larger mills popping up, and you might have a plant manager or a maintenance manager with some experience, but the actual operators—the folks doing the work—are all green, they’re fresh, they’re new,” says Travis Fetzer, an aftermarket coordinator for Andritz. “They don’t recognize the sounds of a pellet press that isn’t running properly.” While new facilities may not have the tenure that established facilities have, they do know the financial impact of premature failure of these expensive components, and they are increasingly looking to press manufacturers and lubricant providers for ideas.