Something Old Something New
By Pulp & Paper Canada
By Pulp & Paper Canada
What happens when a dryer section is a major production bottleneck and requires imminent replacement — but there’s insufficient funding available for the newest, easiest and most obvious solution? Wh…
What happens when a dryer section is a major production bottleneck and requires imminent replacement — but there’s insufficient funding available for the newest, easiest and most obvious solution? What’s more, if everything went according to plan, a de-bottlenecked dryer solution would mean that the performance in the wet end would need to be upgraded as well. This was all part of the dilemma facing Serge Tremblay, at Cascades’ East Angus, Quebec mill.
But there was more. In his search to find the right supplier partner, Tremblay needed to keep in mind that the right fit would:
understand the mill’s goals and limits, and who could work on the mills terms and timetable.
agree to upgrade, test and install machine parts and pieces pulled together from shuttered mills in Europe and the United States.
have the process savvy, technical competencies and commercial willingness to see his mill as a complete enterprise, not just a bunch of fragmented process islands.
The solution he constructed shows how smart thinking and careful planning can use a limited budget to transform an older machine into a competitive one.
The dryer section on PM3 at Cascades East Angus, which produces kraft bag paper from 100% recycled fiber ranging from 41 to 122 GSM had been installed in 1915. By the late 1990s, its aging cast iron frame was weakened with cracks and repairs that compromised the frame’s structural integrity. Despite frequent maintenance the constant vibration under load not only loosened the sole plates and cracked the concrete foundation, it also caused drive system misalignment, bearing failures, and loose rolls. Even with frequent shutdowns and ongoing maintenance, steam pressure, dryer speed — and critically, production and quality targets — were all severely limited. And the situation was worsening with time.
“It got to the point where basically, the combination of shuts and dryer maintenance was exceeding the time and cost we projected replacing it would take,” Tremblay recalls. “The financials weren’t making sense any more and besides we ultimately would have to produce a higher quality sheet at a lower cost to keep the machine going. And we couldn’t be where we needed to be in the market with a slow, breakdown-prone dryer section.”
Without the available time, budget or the justification for the newest equipment in the dryer section, Tremblay and his team began exploring the alternatives. In 1999, after some solid research work, they found 37 Sandy Hill dryers in a Pennsylvania mill. Six inches wider than PM3’s production width and rated to over four times the operating pressure of the existing cans, the dryer trove was a perfect solution once properly inspected and reconditioned. Later that same year the mill’s detectives found and purchased dryer felt rolls, guide rolls, dryer doctors, guides, and felt stretchers from a Beloit machine built in Italy and installed in France. Now, with the equipment secured, Cascades needed a partner who didn’t care where the components originated and someone with the engineering credentials capable of engineering the used equipment into a high performance dryer section. And then ensure the new section would be installed and ready for start-up at the end of a scheduled two-week shutdown. They found one in GL&V.
The first step was to inspect, disassemble and overhaul the used dryer cylinders and related equipment. This was all done in the field or at GL&V’s 100,000 sq.ft. facility in Hudson Falls, NY. While this was underway, their engineers were designing a new box steel dryer frame to accommodate the newer, faster, wider equipment. After the new frame was fabricated in-house, the entire dryer section — including all the cans and dryer felt rolls, bearing housings, piping, sole plates, motor stands, walkways and rope tail threading system — was assembled and tested at the Hudson Falls facility. By January 2002, the section had been disassembled and was ready for shipment to East Angus.
Work on disassembling the old dryer section and installing the reconditioned equipment began as soon as the mill entered its scheduled shutdown on January 22. With GL&V’s field supervisor supplying technical assistance, the Cascades crew first dismantled the old dryer section. The next step was repairing — and to a large extent, replacing — the nearly 90-year-old foundation, and installing the new sole plate. Now, construction the new dryer section could finally begin.
With many of the framework sections pre-assembled, the new frame took only a few shifts to erect. By the second week of work, the reconditioned dryer drums and felt rolls had been lowered into the new frame. And once these major components were in place, the new drive system, process controls and drainage system were quickly added. Again, the pre-engineering and preparation allowed many of the components to be integrated into subsystems and assemblies that could be installed with a minimum of time, effort and adjustment. As the dryer hood was still being fabricated above, new dryer fabric was being threaded through the nearly completed dryer section. By February 4, less than two weeks later, the project was complete — and Cascades East Angus PM3 had a new dryer section that was ready to handle its first sheet.
“We pushed the button and the dryer section worked perfectly with only a few of the expected bugs to tune out of the system,” Tremblay reports. He continues, “In terms of quality, runability and maintenance, things are totally different now.” Where the old section had to be shut down frequently, the new dryer section has performed for more than a year without any unplanned downtime. And instead of being dryer-limited, PM3 now has excess dryer capacity.
In fact, Cascades is now working on the second phase of the PM3 upgrade: a wet end rebuild that will allow the mill to take full advantage of the dryer section’s total productive capacity — and profit potential. The wet end rebuild will include a new hydraulic headbox with automatic dilution.