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Seat and device for washing cellulose pulp, made of Bagasse and straw, in an upward stream with an upstream washing liquid for better recycling of black ink
Seat and device for washing cellulose pulp, made of Bagasse and straw, in an upward stream with an upstream washing liquid for better recycling of black ink
The pulp is washed using a counter-current technique where the pulp moves upwards and the wash liquor trickles downwards in a vertical tower containing screen elements. The pulp is pushed upwards by a perforated screen plate (2) towards the downward trickle of wash liquor so that the upward movement of pulp and wash liquor displaces black liquor from the pulp by a combination of displacement and diffusion. A method for simultaneously cooling and washing pulp for papermaking which has been produced from a raw material such as straw (from e.g. rice, wheat or oat) or bagasse is carried out immediately after a horizontal screw-type digester and comprises the following steps: (1) washing the cooked material in order to remove black liquor using a counter-current technique where the pulp moves upwards and the wash liquor trickles downwards in a vertical tower containing louver-shaped screen elements; (2) introducing the cooked pulp at a temperature of 130-170[deg]C and consistency of 5-10% to the bottom part of the tower, which contains a conical shape stationary screen (8); and (3) moving a reciprocating circular screen plate with conical holes (3) upwards at a low speed of 50-300 mm/minute, so that the drained pulp is pushed upwards and meets the downward trickle of wash liquor with a lower temperature and progressively cleaner composition, so that this upwa! rd movement of pulp and wash liquor displaces the hot concentrated black liquor from the pulp by a combination of displacement and diffusion.
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