weight range of 26-42 lb and it was at the 36-42 lb range in the base ply where the problem was most noticeable.

In late 2007, Smurfit Stone opted for Ashland’s XD3899 technology, one of the first mills in Canada to do so. It took one month to optimize the dosing. In January 2008, crews opened the headbox and found it was still clean, down to the steel in fact.

Arseneault says the mill just needs to do the boil-
outs at regularly scheduled times. “When we need to
do it for the top headbox, that’s when we do it on the
bottom. The last boilout for PM 3’s bottom headbox
was during the shutdown in May 2009.”
Before the XD3899 program, the PM 3 boilout
schedule was every three to four weeks; now boilouts
are only needed every 12 months on the base ply.

Usually, a treatment is done every 18 hours at the

What’s involved

Ashland product launch manager Jamie Woodward explains what’s involved with the biocide production process. The Spectrum XD3899 biocide is produced onsite using a proprietary dosing system. The dosing system blends the ammonium bromide solution with sodium hypochlorite and mill fresh water under required reaction conditions to ensure 100% conversion of the biocide components. The system also strictly controls the reaction to ensure that only the novel biocide is produced.

A single dosing system can treat up to six different feed points and each feed point can be interlocked with a different signal from the paper machine. A programmable logic controller (PLC) is used for feed skid operation and can be used in conjunction with the mill’s distributed control system.

The biocide is only generated when needed and only in the amount required. Therefore, no biocide is stored on site. In addition, water flushes the system after every dosing cycle. The system performs self-diagnosis and automatically shuts down if an interruption of a component occurs.

The system may also be set up so that it can be
controlled remotely by Ashland personnel should a
problem arise.

machine chest. It’s like a boilout, Arsenault says, but it’s really a cleaning. The mill has found no accumulation in the headbox piping.

He adds that the machine was running well
with the old treatment process. However, when the
Ashland technology was adopted and they looked
at the machine after two months, Arseneault says,
“We wondered what we had been doing in the past.
We were spending the same money but the results
were much better with the XD3899 program. We
were still on the steel. The impact was like night
and day.”
By the middle of January 2009, the mill was able
to see the benefits but it did not realize they were due
to the XD3899 program; trials were continued. Since,
La Tuque has been able to reduce its slime problems,
reduce the number of boilouts and there has been no
unscheduled downtime for cleaning.

The camera system it has on PM 3 shows if slime led to a break but mostly, Arseneault says, it has not been the cause. There are fewer breaks because there is less accumulation in the bottom headbox, leading to an incremental increase in production. But, as Arseneault points out, because PM 3 has frequent grade changes, it is difficult to quantify.

When asked if any other work was done, Arseneault answers, “We didn’t need more than that.”

“Although difficult to quantify, we also feel that our sheet quality is better as well.” As Arseneault explains, a liner machine is more forgiving than a fine paper machine. Today, Arseneault adds, the crews do not have to remove the foils on the machine, which used to create what looked like “worms” on the sheet. Now that there are fewer worms, sheet quality has improved significantly.

“We spent money in the past on small improve-
ments,” Arseneault says. “Now, we spend the same
money for long-term improvements. We spend a
lot less for boilout chemicals and we save a lot time
prepping for a boilout and cleaning afterwards.” PPI

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