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How does your kiln system stack up?
With mill management always on the lookout to improve their drying operations, it was no surprise that a recent kiln drying seminar in Quebec City drew good attendance, and lively conversations.
By Martine Frigon
Wood drying is a crucial step in the lumber production process and being able to achieve best practices in kiln drying can certainly bring a productivity gain and cost savings—both of which are welcome in a very competitive industry.
Essentially, the profitability of a sawmill and the lumber manufacturing process depends on the mill’s ability to maximize the wood’s quality throughout the entire manufacturing process—including kiln drying. Mills aim for rapid, high volume drying of lumber, but also want to turn out a quality product. Kiln drying does add extra value, but mills obviously only want to spend what they need on energy and associated costs.
No doubt this is a shared interest among mill management, since 130 people from Quebec and New Brunswick participated in a seminar on kiln drying in Quebec City in April.
Those attending work for companies such as Resolu, Tembec, Arbec, Barrette-Chapais, Les Chantiers Chibougamau, Materiaux Blanchet, Roland Boulanger et Cie, J. M. Campeau, Bois Daaquam, Produits Forestiers DG, Groupe GDS, Goodfellow, Groupe Crete St-Faustin, Scierie Landrienne, Scierie Clermont Hamel, J.D. Irving, Maibec, Industries Parent, Planchers Mercier, Scierie Chaleur, Bos-Franc, Boisaco, and Bégin et Bégin.
Suppliers also responded to the invitation to attend, with sales persons and technicians representing Comact, USNR, Ideal Combustion, VAB Solutions, MEC, SCS Forest Products, Secovac International, and Cathild. The seminar was also attended by people from the vocational education sector specializing in forestry, like the School of Forestry located in Duchesnay, consultants and CSMO BOIS, the Quebec Wood Processing Industry Sectorial Committee, which is dedicated to promoting vocational and technical training in the industry.
Organized by the Quebec Forest Industry Council (QFIC), the seminar, dedicated to the kiln drying process, was in fact the 19th in as many years. It is always an occasion for sawmillers—especially people involved in kiln drying—researchers and suppliers to exchange information, and get up to speed on drying improvements. “It’s very important for us to organize this event—it’s appreciated by the industry. Each year, more than a hundred people attend the seminar,” says Denis Rousseau, director - quality and markets for the QFIC.
Of course, there are many kiln control systems on the market. Whether it’s on the east coast or the west coast—or in between—a lot of improvements have been made over the years. Data transmission by Wi-Fi using smartphones or tablets is now available, a practice that would not been possible only a decade ago.
And the kiln drying itself continues to evolve. “In the 1950s, we started to build large dryers. Three decades later, we saw the beginning of multi-zone drying kilns, temperature controls, and the use of PCs. Nowadays, customers are more demanding and require higher quality,” says Luiz Oliveira, a scientist for FPInnovations in Vancouver.
Among the products offered by the kiln equipment manufacturers there is the WRC system by Cathild, the VIPII control system by MEC, the AccuStop In-Kiln Moisture Measurement System by Secovac, and the Wireless In-Kiln Moisture Meter system offered by SCS Forest.
The research work of FPInnovations has been instrumental in moving kiln drying forward. It led to, among other products, FPdryStack, which is dedicated to reducing kiln drying costs.
But even when the most recent innovations are applied, it is clear that each piece of equipment must be used optimally. This is true with the deflectors, for instance. Vincent Lavoie, a researcher at FPInnovations, puts the emphasis on appropriate use of this equipment. “The baffles are an important component. They make sure that the air produced by the ventilation system goes into the stacked wood. The air passed through the bypass openings doesn’t dry. “
He added that since the drying rate is linked to the speed of the air flowing in the stack, the more air circulating into the bypasses, the less productivity.
Lavoie’s comment is based on a study done on an industrial kiln that processed spruce. “It showed that when the top baffles are positioned correctly, the air velocity increases by more than 200 ft/min in comparison to when they are not used. That theoretically means a difference in productivity of four per cent.” He also mentions that the baffles must be well matched to the loads, and also set up for intensive use, as they are functioning during each load.
In 2011, Marc Savard, associated with the research centre, led a project in which FPdryStack was implemented in two EACOM Timber sawmills. In collaboration with Michel Gosselin from EACOM, the project analysed the performance of lumber handling practices around the kilns in sawmills located in Nairn Centre and Gogoma, in Ontario. The project evaluated the practices of stickering and stacking, the rough green and dry lumber yard storage and the kiln loading. Performance indicators are used to quantitatively assess these areas to highlight good practices, as well as opportunities for improvements.
Producing 8 feet boards, Gogoma has production of around 100 million board feet per year, while Nairn Centre has production of 150 million board feet annually of random length.
The production of both sawmills are dried in four kilns located in Nairn Centre, including two Irvington-Moore kilns, with a capacity of 230,000 board feet. They are equipped with Wellons control systems, and heated by thermal oil. A third kiln, by COE, has a capacity of 315,000 while the fourth kiln, built by Wellons last year, is the largest, at 350,000 board feet. Both kilns #3 and #4 are natural gas direct-fired. All four kilns have a cross-shaft fan system. Kiln #4 uses the Wellons True Capacitance Moisture Meter System (TCS) automatic kiln shut-down based on actual moisture content versus time, and is accurate to near one percent.
According to Savard and Gosselin, the results have been very positive. “We saw an annual increase of two per cent that was estimated at $375,000 for the production of Nairn and Gogama since the implementation of FPdryStack to monitor our operations,” said Savard. “Among the benefits, it led to lower planer production costs, reduced lumber degrade due to warping and reduced sticker renewing costs”.
Audits are standardized, and they can be completed with Wi-Fi access or a 4G tablet. A secure web site then collects data and shows the results. It’s even possible to benchmark and see the results of other mills/companies that are using the system, without knowing their identity. “It’s an interesting tool because as well as showing your trend through the year, it provides upper management with a comparative analysis of the results, to benchmark with other users in the industry,“ adds Savard.
This is the case with Jonathan Caouette, from Les Chantiers Chibougamau, one of the users of this system. “We have seen significant gains,” he says.
Meanwhile, with the equipment manufacturers, there are many products on the market to improve both the drying process and recapture energy, including the WRC heat recovery system sold by Cathild. “In the conventional process, heat is used to evaporate water from the wood. Then, it is completely released into the atmosphere through the exhaust damper. We have to use this potential energy by transferring it into the air renewal,” says Daniel Rondeau from Cathild.
MEC has the VIPII control and the MC4000 systems. The drying process and the humidity level are controlled with sensors, using an average or their positions in the kiln, with a predetermined program. “It can be monitored by remote access with a computer or a smart phone,” says Guillaume St-Pierre, from MEC. “The MC4000 gives the same precision, whether the temperature is 70°F or 300°F, and the system is able to supervise up to 12 kiln dryers at the same time.”
Secovac International sells the AccuStop In-Kiln Moisture Measurement System. It has ben designed to measure the moisture content of a large sample of lumber at various locations in the kiln during the drying process.
“The system measures moisture content of lumber above and below fibre saturation point. Integrated to Secovac’s software, it monitors the drying process continually, providing real time feedback used to advance the segments of the drying schedule and achieve desired final moisture content within the charge,” says Pierre Gilbert from Secovac. “It reads the humidity of large samples, typically between 250 and 350 boards, and measures full range moisture content within one per cent end point accuracy.”
SCS Forest has the Wireless In-Kiln Moisture measurement system which has options for controlling drying shutdown. “The kiln follows a schedule/recipe for a set amount of time and shuts down at a variable moisture content, and also when a predetermined temperature drop across the load is achieved, and/or when a pre-determined moisture content is completed,” says John Wallace, from SCS Forest.
In addition to systems from the manufacturers, there are also steps that can be taken by individual mills that can help kiln operations. Some ingenuous things have been designed by employees themselves and were presented as part of an annual contest at the QFIC workshop. Workers at Resolu La Dore, in northern Quebec, for example fabricated a vacuum cleaner, designed to clean the interior of the boilers.
And there are other ideas, such as the installation of outdoor lights that swivel to illuminate the interior of a dryer at the entrance, and a sensor to open a dryer vent. Other workers thought to indicate doors (even-odd), which especially helps the lift driver to find the right door during the weekend shift.
The challenges of kiln-drying will continue to be of high interest for sawmill managers. There is little doubt that the twentieth edition of the seminar on wood drying next year will draw a good number of mill people, all wishing to optimize their procedures to satisfy increasingly demanding customers.
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