Holes, sheet breaks and myriad other sheet quality problems can be caused by dirty/ clogged headboxes. Two Canadian mills, Tembec, Temiscaming, QC, and Smurfit-Stone, La Tuque, QC, were looking for a way to alleviate slime-related issues that necessitated frequent clean-outs.
Tembec’s Paperboard Group’s ( Temboard) mill produces 180,000 tonnes/yr of various paperboard grades used in lottery tickets, point of purchase displays, cereal boxes, calendars, tobacco packaging and gum wrapper to name but a few.
The three-ply machine (PM 1) started up in 1989 and was rebuilt in 2002. All production is coated.
The Smurfit-Stone mill celebrated its centennial
in 2008. It produces 560,000 tonnes/yr of pulp that feeds two paper machines: PMs 3 and 4. PM 3, the focus of the work, produces 850 tonnes/day of white top liner. The machine was rebuilt in 1995; a mini-fourdrinier was installed on the top side to produce a two-ply sheet. The press configuration was changed with the addition of a shoe press. The mill also installed a soft nip calender.
While the mills faced different issues, both opted for an Ashland Hercules Water Technologies microbiological control program using Spectrum XD3899 ammonium bromide technology (see Pulp & Paper, November 2004, p. 45). Although this patented biocide has been used for many years by numerous mills in the United States, Europe and Latin America, it was only recently approved for use in Canada.
Temboard mill manager Lori Kilgour said the
decision to use the biocide was part of the mill’s history
of continuous improvement. “We are always trying to
get better. We did have some cleanliness issues in the
headboxes and we were trying to solve that.”
Marc Gamache, wet end superintendent, explains
that the machine has top, filler and back ply headboxes.
Every three to five days, the machine was suffering
breaks because of stalactite-like accumulations dropping
into the stock flow from the top of the slice lip of the top
and bottom headboxes, causing holes and coater breaks.
“We had to stop the machine, open the slices and clean
out the accumulation. There were also large accumula-
tions in the pan underneath the machine.” An analysis of
the deposits also showed a lot of starch, which is a good
food source for microbiological organisms.
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