Bonfiglioli 300 Series planetary reducer replaces cycloidal reducer, improving a pulp mill’s production, while reducing downtime, drive replacement costs and simplifying maintenance.
Introduction
Lincoln Paper and Tissue is a manufacturer of paper and specialty tissue products headquartered in Lincoln, Maine. It produces 60 000 tonnes/year of commodity towel and napkins as well as speciality grade tissue. The mill also makes 68 000 tonnes/yr of specialty high bulk uncoated printing papers.
In the Lincoln process, all liquid waste produced by the mill is pumped to its water treatment plant. The last step in the treatment of this water incorporates a dewatering screw press. This press separates the water from paper waste, chips, ash, bark and other solid waste. The goal of the dewatering process is to remove as much water as possible, as Lincoln then uses the dewatered solids to mix with the fuel to fuel its boiler. The drier it gets the solids, the higher the kilojoules generated.
Lincoln generates about half of its electricity, as the sludge is burned, along with wood, bark and chips, fuelling a digester and a back-pressure steam turbine. The alternative to burning this sludge is trucking it to a local landfill, which is not only expensive, but it is counter to Lincoln’s environmental policy.
By converting the biomass solids and wood wastes left to steam and electricity, Lincoln saves over 34 million litres of fuel oil, while also reducing air impacts and greenhouse gas emissions annually.
“The screw press is a vital part of our water treatment process,” according to John Sutherland, Lincoln’s utilities maintenance superintendent, “The reliability of the gearbox on this press is crucial for the mill.”
Downtime on this machine is very expensive, not only in terms of gearbox cost, but in man-hours and lost production. If the 22 to 27 tonnes of sludge being dewatered each day is interrupted, costs could reach into thousands and thousands of dollars.”
The screw press the mill purchased was imported from Japan and used a cycloidal type gearbox, of which. Sutherland said, “We are lucky if we could get 12 months from it. I was getting tired of replacing a gearbox that underperformed, was not repairable and was overpriced. Whenever we disassembled the cycloidal unit, in hope of repair, we would find half a kilogram of metal sitting in the bottom of the gearbox and rollers broken in half. It was a total loss, as fixing it cost more than a new one. That is when I started looking at different solutions.”
Randy Bryant and Wes Archer, project manager of Lane Conveyors and Drives, (based in Brewer, Maine), Lincoln’s trusted local supplier for power transmission equipment, recommended the Bonfiglioli 300 Series planetary reducer.
His recommendation was based on his experience with Bonfiglioli units used on various skid steers used in the forest products industry. Bryant said, ”The 300 Series’ ductile iron housings, tapered roller bearings and internal splines gave the 300 Series the shock load capability that made it the right box for the Lincoln screw press application.”
Lane Conveyors and Drives made the job easy for Lincoln by fabricating special feet for the 300 Series and a ‘drop-in’ base plate. These modifications allowed Lincoln to make a quick, painless transition from the cycloidal unit to the planetary reducer.
“The Bonfiglioli 300 Series planetary reducer allows us to run at the upper limits of the press on what was overload for the cycloidal unit,” Sutherland concludes.
For more information contact Bonfiglioli Power Transmission, +27 (0)11 608 2030, [email protected], www.bonfiglioli.co.za
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