Gentle chip drying

Gentle chip drying

Belt dryer enhances quality and reduces emissions
In chipboard production, usually drum dryers are utilized to dehydrate the chips. More and more frequently, though, also belt dryers are used. A company that recently switched from drum to belt is Italian board manufacturer Invernizzi. The company especially appreciates the massive reductions in emissions.

With about 100,000 hectares, Italy has one of the largest poplar populations of Europe, which are turned into more than 200,000 m3/ yr of veneer and plywood products in the Apennine country. A firm that is committed to this light and fast-growing wood is the long-standing manufacturer Invernizzi. At the production site close to Cremona, 150,000 t of poplar wood are processed into planar basic materials.
High-grade round wood is used for plywood production. Material not suited for this application is further processed into chipboards or used for thermal processing. For a few months now, Invernizzi has been using a belt dryer from Bavarian drying specialist Stela Laxhuber, Massing/DE, to dry chips for chipboard production where wood moisture is reduced from 50 % to 1 to 2.5 %. The system has a capacity of 5 t/h.

Better drying results
Over decades, Invernizzi used a drum dryer to dehydrate the poplar chips. Now, the enterprise opted for a belt dryer by Stela Laxhuber for the first time. Project leader Stefano Fantini explains that better drying results, the omission of pollution and reduced energy consumption were the main motives for the switch.
The drying temperature in the system is less than 100°C, which leads to significantly longer retention times of 20 to 30 minutes for the chips. „Thanks to this gentle way of drying, we achieve way more homogeneous results. Furthermore, fine material is no longer being burnt which has a positive effect on the colouring of chipboards“, Fantini reports during his visit to Timber-Online. Stela Laxhuber‘ s sales manager Tobias Latein adds that this gentle drying process leaves more lignin and terpene in the wood which benefits the glue application during board production.
Another advantage is the reduced drying temperature, Fantini says: „We used to be dependent on high-temperature thermal oil for dehydrating the chips. Now, hot water is all we need.“ The thermal energy consumption now equals those of drum dryers, but the level of power consumption is less.

No dust – no filter
Belt dryers generally cause higher investment costs than drum dryers. „For a realistic comparison, however, one also has to take the required filter systems into account. Then it turns out that the costs are about the same“, Latein informs and adds that Stela belt dryers basically only emit water. Dust emissions without filter remain below 5 mg/ Nm3 – and the values for VOC and aerosol (blue haze) are below required thresholds, as well.

Only the beginning
By now, Stela Laxhuber has already built more than 20 belt dryers with final moisture rates of under 2 % for the wood materials industry. These include large-scale facilities of 60 t/h for OSB production and dryers for block manufacturing. Latein sees this as only the beginning of a big trend: „No matter what you look at – usability, product quality, emission rates, costs or energy consumption – belt dryers are the better solution in every respect.“ An assumption that, several months after switching systems, Invernizzi wholeheartedly agrees with

Project leader Stefano Fantini is very satisfied with the switch from drum to belt dryer.

Title: Italian chipboard producer Invernizzi is now dehydrating poplar chips by means of this belt dryer by Stela Laxhuber. The system‘s capacity is 5 T/h

Holzkurier 2017-12-21, issue 51-52  
Editor: Günther Jauk

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