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RECYCLED FIBRE PROCESSING WORLD PULPPAPER18 The HDS capability of uniform heating due to retention time is a crucial part in maximising the efficiency. After passing the plates the pulp is diluted and cooled this will stabilise the contaminants in a non-tacky state. Later increases in temperature will not reactivate the tackiness and the contaminants will go with the paper through the machine without adhering to wires felts rolls or dryer cans. The installation of an HDS will lead to higher yield through less reject and less fines creation as well as less additives for stickie control on the machine and less down time for solvent cleaning. BACTERIA AND SPORES Retention time at high temperatures and high consistency at plus 30 sets the reduction of bacteria and spores at a very high level. Normally it will be some 99 thus dramatically reducing the need for biocides etc. PHYSICAL PROPERTIES Further developments have the added benefit of significant fibre development in regards to strength. This is made possible by the treatment at both high consistency and temperature. The flexibility of the fibre under these conditions allows for a controlled defibrillation that results in very high strength development without excess creation of fines. In full scale installations as well as pilot plant trials the following improvements have been seen on average 40 tensile 60 Burst and 20 Tear. The energy needed to reach these levels of strength development is very small. The disperser consumes about 35-40 kWhMTon 1.75 2.0 hPd STon. This energy can easily be saved in the low consistency refining stages. Mills today see that with a Krima they can compensate for the lower quality fibre source and keep their raw material costs in check. In many cases mills today are adding basis weight to the sheet to keep within specifications and to compensate for lower quality fibre. By adding an HDS system not only will a clean sheet be produced but the strength will be improved so that the basis weight can be reduced back to normal levels again. ENERGY There is a widespread misconception that dispersion uses a lot of energy. That might be true for some technologies both new and old but when it comes to the HDS nothing could be further from the truth. There are basically 2 energy inputs into the system electrical and steam. As already mentioned the electrical energy used in the HDS is almost always saved in refiners and deflakers. As for the steam it is important toFigure 3. Importance of time and temperature In many cases mills today are adding basis weight to the sheet to keep within specifications and to compensate for lower quality fibre