The majority of the sawn products is converted by the company into solid glulam panels for the furniture industry and shipped all over the world. For kiln drying of timber, the Finns have been using Austrian technology for years.
Kohiwood in Soini, Finland, is anything but an ordinary sawmill. The company was founded in 1987, but following the collapse of the domestic construction industry in the early 1990s, it focussed on glued laminated furniture components and panels. In addition to window and door components, Kohiwood mainly produces single and triple-layer solid glulam panels. The customer base includes furniture manufacturers all over the world, with the main markets located in Europe, Asia and North Africa.
Of particularly note is the nature of the raw material used. Kohiwood only uses round wood from the second thinning. These exceptionally thin pine and spruce logs have a maximum length of 3 m and are 90% sourced within a radius of 100 km. Using two sawing lines, the company produces around 90,000 cubic metres of furniture grade sawn timber every year. Two thirds of this output is processed internally within the company, and the rest is sold externally. "Our customers value the continuous high quality of our products," explains Anssi Hintsa, one of the joint managing directors.
For use in the furniture industry, Kohiwood must dry its lamellar timber slats to a wood moisture content of 10% - a level where moisture removal is associated with considerable expense. "Nevertheless, quality and cost-effectiveness have to be right," emphasises Anssi Hintsa. Since the turn of the century, the Finnish company has also been operating Mühlböck drying chambers. Back then, the company invested in a new sawing line, a heating plant and six fresh air - exhaust drying kilns from the Upper Austrian specialist in timber drying - a decision that Anssi Hintsa has never come to regret: "We are absolutely convinced that technologically Mühlböck is one step ahead. Furthermore, our customers are very satisfied with the drying quality.” In 2014 Anssi Hintsa contacted Mühlböck once more. This time it was about an increase in capacity. The decision lay between several fresh air - exhaust (batch) kilns or a progressive tunnel dryer. "That it should be a Mühlböck product again was taken for granted from the very start," recalls Anssi Hintsa. But after a long deliberation, a fire in September 2015 brought matters to a head. The company had to act and invested in a type 1003 progressive tunnel dryer. With a net volume of 777 m3 and an overall length of 87 m, the energy saving tunnel has an annual throughput capacity of 40,000 m3.
Type 1003 saves energy
Unlike a conventional drying plant, the Type 1003 heat recovery system heats up the fresh air for one drying zone using the full heat energy of the exhaust air from another zone. "The effectively heated “for free” air is used for pre-drying," explains Richard Mühlböck, who acted as project manager. There are three drying zones: pre-, main and post-drying zones. About half of the moisture is removed in the first zone. The main and post-drying sections remove the remaining water from the timber. The exhaust air from the main and post-drying zones flows through a heat exchanger. During this process, the amount of water previously extracted from the wood condenses, whereby a large part of the energy consumed is recovered. The dehumidified exhaust air is returned to the dryer. In pre-drying, only the thermal energy from heat recovery is utilised. The air for the pre-dryer is drawn over the dried wood in the exit zone, absorbing its residual heat. This air then flows through the space for services under the roof, which houses all the heating pipework, and absorbs the heat that is present there. "This allows us to avoid insulation losses and halve the energy consumption compared to conventional systems," explains Richard Mühlböck.
Always on the spot
The new progressive tunnel dryer has been in operation since July. As with the existing six Mühlböck drying kilns, Anssi Hintsa particularly appreciates the good support and cooperation from the Upper Austrian personnel: "Not only has Mühlböck stuck to all it promises, it also pays close attention to the after-sales support of its equipment. Despite the great distance, small problems are always tackled and fixed." Providing support for the plant over the entire life cycle is part of the company philosophy for Mühlböck. "Through this service, we remain in touch with our customers - an advantage for both parties, as the collaboration with Kohiwood shows very clearly," concludes Richard Mühlböck.