DEWATERING ARRANGEMENT ADAPTED TO USE IN A TWIN-WIRE DEWATERING SECTION OF A STOCK PROCESSING MACHINE

摘要

Dewatering arrangement adapted to use in a twin-wire dewatering section of a stock processing machine, comprising a single-ply head box (4) for supplying stock through a nozzle (8) with an inlet (11 ) fed by a tube bank (6) with tubes (7) of non-circular cross- section, a closed loop first wire (2) adapted to receive the stock from the head box (4) on its upper surface and with pressure pulse generating blades (5) mounted inside the loop, a closed loop second wire (3) adapted to be fed on top of the first wire (2), and with pressure pulse generating blades (13) mounted inside the loop, thereby pressing the stock between itself and the first wire (2). The inlet height of the headbox nozzle (8), defined as the total tube bank height minus the total upstream thickness of eventual nozzle vanes (14), is at least 150 mm. By using a larger height of the headbox nozzle it is possible to lessen the risk of formation damages and also to use a higher slice opening, without formation disturbances. This in turn also gives better potential for paper strength and formation. The arrangement is suitable to both paper and paper board machines.