Holmen Braviken: Small steps to big improvements
The Holmen Group’s Braviken Paper Mill, situated in eastern Sweden, has always prided itself on being at the top of its game when it comes to production efficiency and quality of final product. When it needed to further enhance its TMP’s capacity and efficiency – but crucially keep costs to a minimum – ANDRITZ was at hand to provide a tailor-made solution.
A walk through the entrance to the Braviken Paper Mill tells one that the paper machines at this mill were once thoroughbreds in the world of newsprint production – the walls here are adorned with congratulatory world record-breaking plaques heralding a different time in the 1970s and 80s.
Fredrik Bragsjö, TMP Manager at Braviken says, “Our whole business landscape has changed over the years. At one time we were sending newsprint all over Europe, now we are much more focused on producing high-quality, wood-containing SC papers for large volume catalogues. We also produce book papers here at Braviken.”
A MIXTURE OF OLD AND NEW
The TMP plant at the mill is very much a mixture of old and new equipment, and the old TMP lines were pioneers in TMP pulp for newsprint paper. “We have always had a mindset of continuously improving existing equipment at the mill,” says Olle Lindeberg, Production Engineer, Braviken. “And it’s not always about the glamorous picture of installing all things big, shiny, and new. At this time of a highly competitive environment, often you have to roll up your sleeves and deal with the older equipment, make it better, take smaller but effective steps, gradually eliminating the bottlenecks.”
The latest in the line of many small-step improvements at the mill was the rebuild of its “BR1” reject refiner. “We wanted to improve the quality of the pulp, increase tensile strength, and reduce shives with the aim of making the pulp more suitable for a smooth surface on the paper we produce. And of course, look for ways to reduce energy,” says Bragsjö.
Erik Muggerud, Senior Process Specialist, ANDRITZ, adds, “The mill also wanted an increased capacity and simplification of its BR1 reject refiner. The main goal was to create a barrier (plug) for steam as close as possible to the refiner to be able to increase the production rate, at the same time as reducing energy usage.”
A TAILOR-MADE SOLUTION
Due to the many rebuilds over the years, a simplification between the reject screw press and the refiner meant taking out some of the old equipment, but also reusing as much as possible of the existing equipment. A side entry plug feeder, chute, and level conveyor were then installed as well as a new ribbon feeder housing. The complexity of the project and space constraints in the refiner area meant that it was not possible to use standard equipment and the ANDRITZ team had to innovate with a tailor-made engineered solution.
Removal and erection work started in September 2017 with start-up taking place just five days later.
Crucially, and one of the bonuses of moving the plug as close as possible to the
refiner, safety at the TMP plant has been greatly improved. Muggerud says, “The reject pulp will not have to cope with the backflow of steam that can plug the chute down to the refiner feed. There is always a danger to operators when plugged pulp needs to be removed from the chute; this makes a big difference to safety at the mill.”