Twenty years ago, Voith (Germany) launched its first disc filter sectors that operated entirely without filter bags and substantially improved machine availability. Low maintenance requirement, long service lives and a consistently excellent filtrate quality have made the products of the BaglessPlus family a market leader. To mark this anniversary, Voith is once again setting the benchmark for filter segments with its new development FloWing. Existing machines can be adapted to the BaglessPlus family, including the new generation product FloWing.

When it tested the first prototypes of the BaglessPlus disc filter sectors in 1998, Voith revolutionized the dewatering process in the stock preparation unit. Since then, the Heidenheim technology group has installed more than 6,500 filter discs, consisting of more than 130,000 BaglessPlus sectors, and is the undisputed market leader in this area. Worldwide, disc filters with BaglessPlus sectors have paved the way for efficient and resource-conserving dewatering.

Prior to the launch of BaglessPlus, filter discs were regarded as wear parts that paper manufacturers had to replace after around two to four years in operation. For filter discs from the BaglessPlus family, on the other hand, service lives of more than 15 years are usual. Overall, about 93.5 percent of all first generation filter discs installed are still in operation today. In the first ten years after their introduction, there was not a single failure due to wear. At Leipa, where BaglessPlus filter discs have been used since 2004, Voith only had to replace a few of the total 67 discs installed so far. The first BaglessPlus sectors, which Voith installed in 1998, are also still being used today. These long service lives allow manufacturers to significantly reduce the operating costs of their machine.

The filter bags commonly used in conventional disc filters are responsible for a lot of shutdowns in the stock preparation unit. They repeatedly tear during operation, which results in corresponding fiber losses. The filtrate, which is usually used at various spray nozzles on the paper machine, is also contaminated by fibers and fines, which clog up the nozzles and result in the system having to be shut down for cleaning.

BaglessPlus technology from Voith introduced filter discs without high-maintenance filter bags to the market for the very first time. This resulted in a reduction of downtimes, because the BaglessPlus discs reliably maintain the high quality of the filtrate over the entire service life. At the same time, paper producers can save fibers and fillers. The cost efficiency of the system is also improved because spray water with low solids content has a positive impact on felt service life. Thanks to the high filtrate quality, the fresh water requirement for the entire plant is also reduced. Ideally, a closed loop system is achieved.

To coincide with the 20th anniversary of the BaglessPlus system, Voith presents FloWing, the logical development of the proven technology. Practical experience with BaglessPlus over the last two decades enabled Voith engineers to gain crucial insights for the development of the new generation FloWing. Among other things, they investigated the effects of different disc surfaces and topographies on the capacity. At the same time, the new development needed to retain the excellent knock-off properties and high filtrate quality of the BaglessPlus sectors. This resulted in a geometry that allows the formation of a thick fiber mat but also ensures ideal fiber separation.

Thanks to a unique wing design, the FloWing filter sectors have a 56% larger surface than conventional systems. Compared with BaglessPlus discs, the surface has increased by around 30%. Depending on raw material quality, there is therefore an increase in throughput of 20 to 30 percent. FloWing disc filter sectors are even stronger at critical positions and therefore allow for longer service lives than the previous BaglessPlus sectors. 

In July 2018, the first FloWing filter discs were installed in a European testliner facility. The initial reaction from the Managing Director for Production and Technology has been positive: "Since start-up, we have had no more capacity problems, even in the event of high tonnage at the PM. This was not the case in the past."

Thanks to optional adjustments, FloWing filter discs, like all Voith products from the BaglessPlus family, can be used in existing disc filters, including those from other manufacturers.