“A key goal of modern wood drying kilns is to minimize overall costs. To achieve this, the three pillars of quality, capacity, and energy consumption have to be optimally tailored to the respective requirements, and they also have to be in harmony with one another,” John Karbin, CEO of Valutec, explains.
In this context, the innovative Valmatics 4.0 control system was a key development. This system not only efficiently controls all drying kilns, but also serves as a central point of contact for all process data from a sawmill. “By adopting a holistic approach, we make sure that the drying process responds flexibly to changing parameters. Wood has to be dried precisely to the desired moisture content. Any deviation results in unnecessary costs,” Karbin emphasizes. In combination with detailed simulation models, Valmatics significantly reduces manual labor in daily operation. Operator errors and iterative processes when introducing new drying programs are almost completely eliminated. “We can simulate any process sequence with a deviation of less than one percent. If the input moisture content, quality, dimension, or target moisture content change, we make adjustments in real time without affecting plant availability,” Karbin says.
“Closed Loop Drying”
The two masterminds behind Valutec’s innovative developments: CEO John Karbin and Robert Larsson, inventor of “Closed Loop Drying” and responsible for Business Development (from left) © Raphael Kerschbaumer
However, even the best control system eventually reaches its physical limits. “We cannot change the laws of physics and thermodynamics, but we can change the plant design. There is still great potential here,” Robert Larsson, former CEO and now responsible for Business Development at Valutec, explains. With the new, patent-pending closed air circulation system, this potential has been realized in what the manufacturer calls a groundbreaking product: In the two zones of the continuous kiln, there is no longer any exchange of air with the atmosphere. Instead, each zone has a self-contained and precisely controllable microclimate.
The air drawn in at the kiln’s outlet remains in the system, passes through the kiln in the opposite direction to the material flow, and is then released in the kiln’s heating zone, with minimal difference to the ambient conditions. Fresh air is used only for cooling in the heat exchanger and does not come into contact with the drying zones. “We use the heat exchanger exclusively to dry the air, which is then fed back into the process. This enables a threefold use of energy,” Larsson tells us.
The idea was to develop a continuous kiln that has no exchange with the ambient air – a self-contained system that drastically reduces energy consumption. We succeeded at that.
Energy consumption reduced by up to 50%
The result is significantly lower energy demand. “The potential for heat savings is huge – up to 50% are possible. Furthermore, we reduce seasonal fluctuations and achieve constant energy consumption throughout the year,” Larsson emphasizes. Since energy costs are rising worldwide, this aspect adds to the system’s economic attractiveness. Furthermore, excess heat from the biomass plant can be fed into district heating networks or used to generate electricity, which provides an additional source of income for sawmills.
Close development partnership
In constant close contact: Robin Holmbom (left) and Eric Johansson (2nd from right) alongside Norra Timber’s Joakim Larsson (2nd from left) and Anders Lindgren in front of the TC continuous kiln at the Kåge sawmill © Raphael Kerschbaumer
Swedish sawmill group Norra Timber has consistently benefited early on from Valutec’s various innovations. At its three sawmills in Kåge, Sävar, and Hissmofors, the group produces a total of around 800,000 m³ of softwood lumber a year. The Kåge sawmill alone accounts for around 300,000 m³ a year. Located directly by the sea and just a few kilometers from the outskirts of Skellefteå, the mill is in close proximity to Valutec’s headquarters. This proximity has helped create a particularly close partnership, which is rarely found in the industry. “Our partnership goes beyond a traditional customer-supplier relationship. Norra Timber is actively involved in our development processes, and we test new solutions at the company’s sites under real-life conditions,” Valutec’s Eric Johansson tells us.
“In return, we always receive the latest technology – which gives us a clear competitive edge,” Anders Lindgren, drying kiln operator at Norra Timber, adds. “Wood drying is a particularly critical process. Errors immediately have a negative impact on the quality of the lumber and result in high costs. Thanks to our close cooperation with Valutec, we make sure that this does not happen,” Joakim Larsson, sawmill manager in Kåge, comments.
Norra Timber was also one of the first companies to fully implement Valmatics 4.0. “It is hard to admit, but the simulator works really well. We could never achieve this level of precision manually. Changes and adjustments would not be possible at this speed. This has noticeably improved the sawmill as a whole,” Lindgren tells us, and Joakim Larsson adds: “After we had installed the first TC continuous kiln in 2017, we were surprised by the results. Quality and throughput are spot on. Our employees in the planing mill can tell at a glance which packages come from the continuous kiln and which were dried with the old existing systems.”
