No room for errors

With a total annual capacity of 2.5 million tons of pulp, paper and containerboard, Vancouver-based Catalyst Paper Corp. has no time for shutdowns and no room for errors. But aging drive technology and limited access to replacement parts at its Port Alberni division in British Columbia was causing lengthy and costly shutdowns on one of its three paper machines.

To boost machine reliability and reduce downtime costs, Catalyst turned to a drive system upgrade. The solution provides Catalyst with greater access to technical support and parts, improved diagnostics, increased uptime and reduced maintenance costs.

Catalyst, which changed its name from NorskeCanada in October 2005, is among North America’s leading producers of mechanical printing papers with an annual capacity of 2.4 million tonnes. With 3,800 employees, 12 paper machines and four divisions within 160 km of each other, Catalyst serves publishers and commercial printers in major markets in North America, Latin America and Asia.

Located at the head of Alberni Inlet on the west coast of Vancouver Island, the company’s Port Alberni division is one of the largest producers of telephone directory and lightweight coated papers in North America. With 432,000 tons of groundwood paper capacity annually, the Port Alberni division manufactures papers that are used to print a wide spectrum of products, including telephone books, magazines, catalogues, flyers and airline schedules.

The challenge

The drives on Port Alberni’s No. 3 paper machine were experiencing increased downtime and were difficult to maintain. The original drive manufacturer no longer supported this older technology, and securing replacement parts was an ongoing challenge, which was compounded by Port Alberni’s remote location on Vancouver Island. Moreover, the control system’s limited diagnostics made troubleshooting tedious and time consuming.

“We were becoming increasingly concerned about product support and machine reliability,” said Darryl Hatch, project engineer at Catalyst’s Port Alberni division. “The existing drives were extremely outdated, and without a reliable source for replacement parts and repair service, we were constantly putting our production operation at risk of incurring substantial downtime losses.”

To minimize the cost of the retrofit, Catalyst wanted to keep the current wiring footprint in place, including cabinets and disconnects, as well as the existing DC motors. This would require integrating new, large-horsepower drives and replacing entire power modules within the existing cabinet space. Adding to the challenge was an extremely tight time frame that required installing a tested, fully functional system within a three-day window.

The solution

The retrofit included eight digital DC drives from Rockwell Automation, ranging in size from 30 hp to 1,000 hp.

A 1,000-hp drive provides precise control of the paper machine’s secondary fan pump, which pumps a diluted pulp mixture into a headbox. From there, the mixture is diverted onto a continuously moving wire screen, with the speed controlled by another 1,000-hp drive. It is during this process that the pulp begins to transform into continuous paper. Water is removed by gravity and with the help of vacuum pressure.

The paper is then passed to a press section (powered by two 720-hp drives) where a series of rollers squeeze and remove more water. In the final section, the paper goes through a calendaring process where large rollers are used to smooth the surface of the paper before it is wound onto large spools.

The machine produces paper at a rate of about 3,500 feet per minute. Catalyst sells the 270-in.-wide rolls for use in the production of telephone directories.

The retrofit also includes an updated version of the existing Rockwell Automation distributed control system, which provides all-digital drive control and operator interface functions. To simplify operations, the machine uses operating system software from Rockwell Automation to provide supervisory control, monitoring and diagnostics, and report generation. The machine employs two Allen-Bradley PanelView operator interfaces linked to the control system via DeviceNet.

The results

The ability to precisely control the speed of the large motors powering the secondary fan pump is critical in the forming of the paper. Compared to the older analogue drives, which lacked precision and stability, the new DC drives provide tighter, integrated control of the machine’s wet end interlocking functions — resulting in less variability and fewer unexplained shutdowns.

“Over a 16-month period beginning in 2001, we lost more than $165,000 in production downtime due to unexplained drive failures,” Hatch said. “Since then, after the retrofit, our downtime has been virtually eliminated.”

The system offers improved diagnostics, enabling operators to identify problems early and help prevent downtime events from occurring. Another key benefit is improved control flexibility. “For example, to tune the analogue drives, an engineer had to calculate what value of resistance and capacitance to solder onto the circuit board — a complex and time-consuming task,” Hatch said. “With the digital drives, we can simply enter the desired adjustment or tuning parameters, and the change is instantly and automatically computed.”

The installation, which was initially a big concern, was actually completed ahead of schedule and well within the allotted three-day timeframe.

“We picked a good team of our own electricians and had an excellent team from Rockwell Automation, which was key in making the installation a smooth success,” Hatch said. “In fact, one of our division managers commented that this was the smoothest drives installation and start-up he had ever witnessed.”

System support and access to spare parts is also no longer an issue with the new system.

“Rockwell Automation’s extensive support capabilities were a significant factor in our selection,” Hatch said. “We now have a local Rockwell support person who is able to provide ongoing maintenance and troubleshoot any problems that might arise. That’s critically important for us.”

The drive retrofit gives Catalyst a high-performance system that is easier to operate, maintain and upgrade. With this success, Norske next planned to upgrade its No. 4 paper machine, which also used older drive technology.

This article was provided by Rockwell Automation Inc., Milwaukee, Wisc., www.rockwellautomation.com.