Pulp mill plots path to plant-wide protocol

Source: PlantServices.com

Feb 08, 2006

Established in 1990, the Peace River Pulp mill in Alberta still had its original control system in place in 2004 when suppliers declared the equipment obsolete. Difficulty in finding replacement parts, unreliable service, and declining operational knowledge and training options forced the mill to find a new automation solution.

The mill produces more than 480,000 tons of wood pulp per year for printing- and writing-grade paper. Aspen and white spruce are conveyed, screened and diced into chips, then cleaned, cooked, bleached and cut in multiple pressure- and temperature-controlled processes that turn them into pulp bales.

Discrete I/O in each of the 14 process areas are controlled by separate PLCs.

Several considerations went into selecting a vendor for the project:

  • Mill technicians didn’t want to deal with multiple, small vendors, so it was important to find a single supplier.
  • Diminishing in-house expertise led to an open control platform that would be easier to operate and maintain.
  • The existing controllers used proprietary communications, so the mill needed a new, open communication network to allow production lines to exchange operating and status information with the main control room.
  • The selection committee knew it would keep the existing Reliance AutoMax drive system, but recognized a need for a powerful, more flexible control platform that would be simpler to operate, maintain and troubleshoot.

“We needed a system that could integrate seamlessly with our core machinery,” says Gord Gargus, project coordinator, Peace River Pulp. “And we needed a technology platform that could grow with us to meet our ongoing needs and also allow us to more easily maintain and troubleshoot problems in-house.”

A review of supplier credentials, total cost of ownership, scalability, communication technology and local support for programming and ongoing assistance led the plant to select Rockwell Automation, its Integrated Architecture and the Allen-Bradley ControlLogix platform.

The team decided to convert the bale line first because it had no distributed control system interface and would have the least effect on production should any problems arise. The bale line is the final stop for the pulp. Two identical lines press the pulp (stacked in 32-in.-square sheets), measure weight and moisture content, wrap, tie and mark it for distribution.

The Peace River Pulp committee engaged Rockwell Automation engineering specialists to assist with the hardware design and to install, in 10 days, the new controller program for the bale line. “Since this was our first control system upgrade, we wanted to reduce as much risk as possible,” says Gargus. “We found the Rockwell Automation engineers had superior knowledge and familiarity with the programming tools and control hardware for the ControlLogix platform, which helped reduce a lot of our stress and accelerated the installation process.”

Rockwell Automation engineers worked with the Peace River Pulp project team to perform code reviews and establish testing procedures. Software issues were resolved early in the design process so the controller could be installed and started with minimal on-site effort or process disruption.

In-house technicians and electricians pre-wired a ControlNet network and prepared to convert the field I/O to ControlLogix rack and Flex I/O while Rockwell Automation engineers programmed and tested the equipment.

When it came time for the bale line to switch to the new control system, Rockwell Automation was able to quickly certify the network infrastructure and the transition went smoothly.

“The bale line worked the first time right out of the gate. We were thrilled that all the hard work and collaboration paid off,” Gargus says. “Issues were resolved during testing phases without increasing the project cost or time to implement.”

Before the control system cutover, Rockwell Automation conducted four weeks of on-site training highlighting the capabilities of the new technology and how it would improve troubleshooting. They reinforced the training during installation, and in-house technicians are now able to maintain, troubleshoot and repair the new equipment. In total, 26 Peace River Pulp E&I technicians were trained on the programming tools, hardware operation and maintenance, and how to make online changes and troubleshoot the new network.

With the new control system in place and operators fully trained,
Peace River Pulp is now spending considerably less time troubleshooting the line. Just weeks after the installation, a bale line operator encountered a jam in the process. This sort of problem would have taken hours to identify and solve with the old controller, but now it took only 30 minutes to get the line up and running.