Mill Solutions: Production Dream & Maintenance Nightmare
By Pulp & Paper Canada
By Pulp & Paper Canada
With the present market situation, the North American market will probably not see much added capacity in the near future. Low company profits have put existing pulp and paper mills in a desperate sit…
With the present market situation, the North American market will probably not see much added capacity in the near future. Low company profits have put existing pulp and paper mills in a desperate situation to reduce costs, since major investments have been curtailed. The only exception is money spent to keep the mill operational. From this perspective, both mills and suppliers have realized that cooperation is mandatory to reduce mill production costs.
Trust — a new challenge for the supplier
In most kraft mills, the production rate shows little change from year to year. With virtually no modernization or upgrading, many mills slowly begin to operate their equipment and processes very inefficiently, sometimes without having registered the difference. This situation only becomes critical by comparison with competitors.
However, supplier competition will bring new ideas into the marketplace and, with these new ideas, come new solutions, new possibilities and, in the end, new revenue. The key in the near future is to optimize the existing processes and equipment to meet the current mill operating cost and production demands.
Solving specific needs
“Overall service is of the utmost importance for us,” said Pierre Slusarek, assistant supervisor at the mill, “since we intend to continue producing pulp and paper and therefore need suppliers to assist with equipment and know-how. But we also understand that selecting a supplier is important. Technologies and know-how differ and…it is important to have a deep and thorough understanding of the process as well as of the equipment.”
He summarized it by saying that what the mill needed to find was a supplier who could give the right proposals and provide the right solutions. As he points out, no two mills are alike and therefore it is of vital importance that the supplier is able to understand specific conditions.
“And with us it is not only one digester,” he continued, “but 19 batch and three continuous digesters followed by five washing lines, 14 screens and finally two bleach plants before the two paper machines.”
Technical support needed
“Choosing a supplier depends on the product or services being purchased,” said Slusarek, “but we value technical knowledge and always try to get as much technical support as possible. Other key factors to consider are the production costs in dollars/ton produced, equipment lifespan, ease of maintenance and, in the end, service availability. The supplier who is able to come on short notice when we have a problem, has good R&D and expertise is always welcome.”
With capital hard to come by, many of the ageing mills in Canada need modernization. For the LaTuque situation, Slusarek credits Kvaerner for their European business model and the fact that they do not concentrate on selling their own product but will take the time to look at the problem and suggest minor upgrades or retrofits to improve mechanical reliability and solve process headaches.
“Significant equipment improvement has been made in the cooking area based on ideas they have provided,” concluded Slusarek “We have been able to lower production cost and improve equipment reliability.”
“We have very good cooperation between production and maintenance people and we even sit together”, said Jacques Dry, maintenance engineer at the pulp mill. “The spirit in the group is very good and it’s really fun to work. It makes a big difference in the morning when you wake up and you are happy to go to work.”
Dry describes almost all the equipment at the mill as being old. Quite a number of machines need to be maintained and serviced on a daily basis, resulting in a big fleet of spares. There are four low-pressure feeders and four high-pressure feeders in operation on three continuous digesters. There are also five low-pressure feeders and four high-pressure feeders as spares. The total fleet includes equipment of various types, designs and different stages in useful life.
“One can easily imagine that the maintenance of this equipment represents a major portion of my budget,” he said. “After a seminar in Montreal, we found a lot of clues to our problems at the mill. From this point onward we have really understood that real deep process know-how is needed to properly understand our specific problems and provide the right solution.
Dry cites a recent example. “I had an inquiry out for a number of new steaming vessel screws to replace some old ones on the sawdust continuous digester. One supplier suggested a straight replacement, but Kvaerner proposed a slightly re-engineered design, which was mechanically much more robust and better, based on my technical knowledge and taste. It was also at a competitive price.
“The result has improved machine reliability as well as improved wintertime operation. The mixing and transfer of steam into the sawdust became more efficient. The changes were inside the steaming vessel, where small stainless steel agitation bars were welded onto the face of the flights of the screw. As a result we went from summer and winter operation to practically summer operation, year around. We could almost maintain the same tonnage year around and that meant another 50 tons/day for the whole winter season. The problem we had encountered was that the sawdust contained ice and snow and consequently was very cold. This caused problems in penetrating the sawdust as well as with heating the chips with steam to reach cooking temperature.”
Another example offered by Dry involved the Asthma feeders, which he claims were rebuilt at a fraction of cost of buying new ones.
“Since the feeders were at the end of their life span,” he explained, “at least regarding casing and rotors, the situation became even more interesting in terms of cost. A sleeve was inserted inside the casing, a brand new rotor was installed and the remaining mechanical components were serviced. The results were dramatic: a virtually new machine that could run another ten years at 30% the cost of a new one. Plus, even after ten years the machines can be renovated again. Quite a saving for us!
“In connection with this project,” Dry continued, “Lauri Lep from Kvaerner recommended we update our process by changing the old-fashioned control system for the Asthma feeders. Sadly Lauri Lep has passed away and we, on our own account, switched from DCS to PLC control of the Asthma valves and as a result we were able to more directly control the sequences in question, with opening and closing times . Lower maintenance cost was a direct result. Now the valve only opens when the pocket is open, not when it is closed. In mechanical terms the operation is much smoother and the feeders will perform longer and with less damage. There was a slight production increase but what we were after was production stability and equipment reliability.”
Feeling confident in the decisions that had been made, Dry described the changes as having made the LaTuque mill more efficient and his own life easier.
“Otherwise you might say that our service and maintenance department had ‘hell’ to keep all the different machines running, while the production guys can lean back, since every little interruption will just affect a minor portion of the production, with all these 22 units producing pulp at La Tuque,” concluded Mr. Dry with a smile.
Smurfit-Stone La Tuque in a nutshell
Who doesn’t remember Canadian International Paper (CIP), Canadian Pacific Forest Products, Avenor or St-Laurent Paperboard — today it’s Smurfit-Stone Container Corporation (SSCC NASDAQ) in La Tuque, a town with some 13,000 inhabitants. The town was built up around the original mill in the early 1910s, but most of today’s mill was built or modernized from the 1960s through the 1980s by CIP.
The mill is one of approximately 15 in the world, based just on sawdust and chips from sawmills. La Tuque has two continuous sawdust digesters, one of which produces 350 tons, the world’s largest. Add to this one continuous digester processing sawmill chips and 19 batch digesters, each one
being 100 m3 in volume cooking 5-6 different grades. The mill has two paper machines producing 300 tons/day of bleach board and 900 tons/day of white top linerboard. Most production is exported to the US with 50% going to internal converting mills. A new strategy has put a lot of effort into safety and housekeeping the last couple of years after some major investments in environmental projects, paper machine upgrades, liquor cycle upgrades and a partial wood yard modernization (approx. CAN $500 million total) from 1995 to year 2000.
ke Nordlander, NordCom International AB, is a consultant for pulp and paper, as well as the shipping world. He writes international reports on current events within both industries.#text2#