Control paper gram weights precisely

October 2012 Valves, Actuators & Pump Control

Founded in 1964, Cascades is a North American leader in the production, conversion, and marketing of packaging products, fine papers, and tissue papers. Internationally, the Cascades Group employs more than 14 000 people and operates some 160 modern and versatile operating units in Canada, the United States, Mexico, France, England, Germany and Sweden. In addition to its brands, Cascades Tissue Group is a major supplier of private label products for major chains and drugstores.

A hundred years of continuous service

Recently the group experienced a concern that outdated controls at its Eau Claire mill would jeopardise its position in the increasingly competitive global paper industry.

Paul Olson, Paper Mill Superintendent, said, “Making tissue that is soft, yet strong and consistently high in quality requires superior control over the moisture and gauging, especially during paper grade changes. Adjusting for basis weight and moisture after a grade change manually can take the better part of an hour, and there is still chance of human error. By automating, we cannot only save time; we also maintain spec and ensure product consistency.”

To meet this challenge, Cascades automated control of moisture and gauging on two tissue machines migrating to a modern Foxboro I/A Series Distributed Control System.

Implementing the new technology

The new Invensys control architecture includes a fault-tolerant I/A Series system controller, a server, two human machine interface (HMI) workstation terminals, with 200-series Fieldbus I/O modules, all communicating across a high-speed Ethernet network. This network configuration enabled the I/O to be located near the tissue machine wet end operation, reducing both control room space and field wiring.

Using this Invensys solution, the operations engineers have implemented regulatory and supervisory control functions using an open system architecture. Operators receive better trending analysis that enables them to correlate variability for each production run. Stock preparation controls help reduce disturbances that can significantly impact paper quality and paper machine performance.

Cascades set out to reduce standard deviation of both basis weight and moisture; the new controls from Invensys met both these objectives. In addition to contributing to product quality, the new system has also reduced breakage in parent webs, resulting in more uptime, greater overall capacity utilisation, and lower maintenance costs.

Another important benefit of the upgrade was laying the foundation for implementing more advanced process controls. For example, the new Foxboro I/A Series Distributed Control System currently uses multivariable expert adaptive control, which reduces consistency swings while enabling performance trending and simplified troubleshooting. This brings greater efficiency in energy utilisation, plus waste and discharge handling. Because components are now housed in a central control room, equipment is not exposed to the corrosive environment of the mill floor.

For more information contact Jaco Markwat, Invensys Operations Management, +27 (0)11 607 8100, [email protected], www.iom.invensys.co.za

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Valves, Actuators & Pump Control

Control paper gram weights precisely

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