Pressure screening apparatus for screening a paper stock suspension and screen clearer for such a screening apparatus

摘要

A pressure screening apparatus for screening a stock suspension and screen clearer for a pressure screening apparatus. The pressure screening apparatus includes an inflow chamber, a suspension inflow connected to one end of the inflow chamber, a reject outflow connected to another end of the inflow chamber, an accepted stock chamber, an acceptance stock pipe connected to the accepted stock chamber, at least one screen element disposed between the inflow chamber and the accepted stock chamber, a screen clearer adapted to move with respect to the at least one screen element for preventing clogging of the at least one screen element, the screen clearer comprising at least a first clearing zone and at least a second clearing zone, the first clearing zone having a plurality of clearing elements and the second clearing zone having a plurality of clearing elements which are different from those of the first clearing zone, wherein the stock suspension flows into the pressure screening apparatus via the suspension inflow such that a portion of the stock suspension flows through the clearing zones and exits the pressure screening apparatus through the reject outflow. The screen clearer includes a substantially cylindrical body having a cylindrical outer surface. The cylindrical outer surface includes at least a first clearing zone and at least a second clearing zone. The first clearing zone has a plurality of clearing elements. The second clearing zone has a plurality of clearing elements which are different from those of the first clearing zone. The cylindrical body is rotatably mountable.