Patent ID: 6808601
Filing Date: 2004-10-26
Classification: D21F

Abstract:
A method for passing dilution water into connection with a stock flow passed from a stock inlet header of a headbox in a paper or board machine, wherein dilution is carried out in at least two stages using in a first dilution stage first valves fitted with a larger mutual spacing at different points of width across the headbox and passing the dilution water through said first valves to desired points of width of the headbox according to the requirement of control of the basis weight of paper or board, and wherein in a second dilution stage (II), dilution water is passed into connection with a stock flow coming from the first dilution stage, said dilution water being controlled by means of second valves, the second valves being fitted with a denser spacing than the first valves of the first dilution stage, and that coarse control of the basis weight profile of the stock is carried out in the first dilution stage and fine control of the basis weight profile of the stock is carried out in the second dilution stage across the width of the machine.