Dust and chip extraction specialist DISA has carried out a £1.2m turnkey project at Finnforest UK Ltd’s Boston, Lincolnshire plant. As well as being one of the largest extraction installations carried out in the UK woodworking industry in recent years, DISA also project managed the building and equipping of a sophisticated woodwaste handling plant.

There are six moulding lines in the mill, each with a Weinig or a Waco high speed moulder. Five of the lines are also equipped with saws for cutting the timber before it is processed in the moulders.

When Finnforest acquired the former Hunter factory it inherited a mixture of elderly chain filter systems, of varying makes, with open cyclones venting the extracted dust laden air into the atmosphere. The extraction needed replacing with a more efficient and uniform system.

“The requirements we set were twofold,” said the company’s engineering manager, Mike Lomas. “Firstly, it was to install state-of-the-art extraction that would allow us to meet current and projected environmental regulations and, secondly, to allow us to increase the capacity and efficiency of some of the moulding lines.”

Mr Lomas and the factory’s former site engineering services manager, Steve Claxton, now production manager at Finnforest’s King’s Lynn facility, took 12 months researching possible extraction equipment suppliers throughout Europe. They eventually narrowed down their possible choice to two: Danish-owned DISA, whose UK head office is at Leeds, and a Dutch company.

After examining DISA extraction systems in operation in the UK and Denmark, it was awarded the contract because of the quality of its equipment and the fact that it had the necessary capabilities to manage the entire job, including the woodwaste plant, as a turnkey project.

Removing the worry

“Doing it this way took away all the worry,” said Mr Lomas. “We placed the £1.2m order for the entire system with DISA, instead of having to deal with builders, electrical contractors and a host of equipment suppliers.”

Each of the six moulding lines is now equipped with a DISA NFK 2000 modular chain filter, varying in capacities from 26,000m3/hr up to 63,000m3/hr, with a total air volume of 250,000m3/hr. Each is powered by a DISA Combifab fan set sized to suit each line, with a total of 14 used throughout the project.

Designed for internal and external use, the NFK 2000 range covers capacities from 1,000 to 500,000m3/hr per filter. Combifab fan sets, available in four basic modules, operate at volumes up to 100,000m3/hr and use a range of motor sizes. They come in direct or belt drive formats and three alternative impeller styles are available for different conditions or waste materials.

A dedicated pneumatic conveying line takes away the bulk of the fine dust created by the saws at source, so that it does not contaminate the shavings. It’s transported to a 300m3 dust storage silo, with dust collected from six cyclones on the way. The dust is then automatically loaded into bulk trailers for despatch to companies who use it in the production of cat litter.

Shavings from each of the moulding lines, and any remaining fine dust, pass through the NFK 2000 filters and are discharged via a common transport loop into an 800m3 capacity storage silo. From there the shavings exit the silo via a push-rod discharge arrangement and are conveyed to a bank of sieves that recover most of the remaining dust, leaving the shavings virtually dust free.

The system has been designed to allow the moulding lines to keep running at all times, which is crucial as the mill operates around the clock. This has been achieved by installing a back-up 300m3 capacity silo, to which the shavings are automatically directed should the main silo fill up. If both silos were to become full, the shavings can be bulk loaded under high pressure into covered trailers.

The size of the extraction project and the amount of materials needed are impressive. DISA installed a total of 2,500m of its QF and flanged ducting. The length of the pneumatic dust conveying line alone is 400m, made up of 315mm diameter QF ducting. Intended primarily for dust collection and the pneumatic transport of materials, QF ducting is available in sizes from 100-500mm in diameter. It can be installed in two-thirds of the time of standard ducting as there is no need for riveting, welding, precise measurements or the use of special tools. It is available in galvanised and stainless steel.

The extraction system incorporates Grecon spark detection equipment throughout to avoid explosions. Guaranteed emission levels are well within current environmental regulations and the equipment is intended to meet the new ATEX directive, covering plant used in a potentially explosive atmosphere, which comes into force in June next year. The warm, extracted air is returned into the mill for space heating and can be released to the atmosphere in warm weather.

DISA designed the modular system so that there is ample room for adding additional capacity should Finnforest decide to introduce a seventh moulding line.

“The self-cleaning DISA filters have allowed us to become more efficient,” said Mr Lomas. “We used to have to shut down the old filters, and therefore the moulding line, three times a day for cleaning. With no shutdowns we have the capability to increase production by one-and-a-half hours a day for each moulding line.”

In addition, energy savings are being achieved by each moulding line operator being able to control the extraction for his work station, shutting it off when-ever the line stops, for tooling changes or meal breaks.

There’s also a better working environment within the mill and no more problems with neighbours caused by escaping dust. Finnforest brings in an external hygiene specialist to check the system every six months and he has commented favourably on the improvement.

The clean wood shavings from the moulding line are used by Finnforest to produce its Hunter brand of bales used for animal bedding, chiefly in the equestrian industry. Its new woodwaste plant is one of the most modern in the country, with fully automatic stacking and an online weatherproof sealing system, making the pallets suitable for outdoor storage. Finnforest specified all the ancillary equipment it wanted, with DISA purchasing, installing and commissioning the plant and supervising the construction of the new building.

A new fully automatic baling plant produces five bales a minute which can all be operated simultaneously. There’s also a new robot stacking machine that can recognise the two different bales sizes produced and stack them accordingly, before they are wrapped and palletised ready for delivery.

Automatic handling

The new automated equipment has allowed Finnforest to reduce the staffing level in the baling plant from five to two per shift, with those displaced relocated to other jobs in the mill. It has also removed the need for manual handling of the bales.

Everything is PLC controlled and linked to a Scarda system, built by DISA, which is an easy-to-read, on-screen graphics display that allows staff to monitor every aspect of the operation from the mill office, with a second display unit in the baling plant.

“It was an extremely complicated project as we had to install everything alongside the old systems, without causing any disruption to production,” said DISA’s sales engineer Paul Costello. “We had a window of four days over a plant shutdown in which to switch over to the new system, which had to work from day one.”

The contract took DISA’s engineers 12 months to complete. This included all the necessary electrical and civil engineering work, commissioning the new extraction, supervising the building, equipping and commissioning of the waste handling plant and decommissioning and dismantling the old extraction equipment.

“DISA worked closely with us as a partner on this major project to enable us to achieve our objectives,” said Mr Lomas. “The end result is that the mill and the waste handling plant have become more efficient. Also, the dust content of the shavings has been substantially reduced, giving us a far higher quality end product.”

DISA’s managing director, David Proud said: “Although we are often involved in smaller extraction projects, being asked to project manage a contract of this magnitude demonstrates our capabilities and our expertise in extraction and associated waste handling.”