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WORLD PULPPAPER 19 especially so on lower basis weights. The HDS is very efficient at separating these bundles and clusters giving the mill a better opportunity to manufacture a better stronger and more uniform product. This deflaking capability of the Krima Disperser is well illustrated in broke handling systems running wet strength and coated broke. BROKE HANDLING Handling wet strength broke normally means use of steam and chemicals. This leads to an energy and environmental impact not acceptable by most producers today. If a Krima HDS is installed in the final parts of the stock prep a side stream of broke can be fed to it. By cutting out chemicals and steam in the pulping stage as well as shortening pulping batch times by 4 to 8 times a pump-able high flake content pulp is produced. This is then fed to the Krima HDS for full deflaking without any need of chemical additives. This results in a full yield and very economical broke handling. BENEFITS AND SAVINGS Furnish cost normally a significant factor. Due to a very efficient sequence YP bleaching significant chemical savings will be realised. Yield there are either no or very minimal rejects in dispersion. Solvent chemical usage on the machine for cleaning. Biocide usage as temperature will eliminate bacteria and spores. Reduction or elimination of refining energy used due to excellent strength development across the Disperser. Less rejected product from the machine due to a more stable quality and a police-like function of the disperser. Improved overall quality and brightness ... small fibre bundles that have not been separated in traditional stock preparation systems will make their way onto the machine mention that the location of the HDS is crucial. Sited at the very end of stock preparation with minimal storage time before the machine the uniformly heated pulp will aid in drainage and pressing allowing for significant savings in the dryer stages and chests. The HDS will also act as a water loop divider keeping the stock prep water from the machine water and thus keeping the latter at a higher quality and more stable temperature. Let us not forget that the heating in the HDS is performed at high consistency in a fully sealed and insulated system making it far more efficient than a chest or hood. UNIFORMITY AND FORMING It is rather common that small fibre bundles that have not been separated in traditional stock preparation systems will make their way onto the machine. This leads to uneven forming which impacts strength and uniformity Case Study 1 A North American board mill conducted their due diligence including trials at Cellwoods pilot facilities in Sweden. The results of the trials were the basis for their decision to install a complete KRIMA HDS. The type of board produced had been severely affected by tacky contaminants and especially bleed through spots that showed up in dryer sections as well as later in converting. Following the HDS installation these problems were eliminated. Another positive effect was strength development as seen on the furnish with 80 OCC and 20 Mixed areas included 40 Tensile Index development this at the same time as a 17 increase in Tear. This they were able to reduce the basis weight on the production it also made it possible to back off low consisten- continuously delivers top quality results with high availability and very low maintenance needs and costs. Figure 4. Strength development in board mill