Patent ID: 6284100
Filing Date: 2001-09-04
Classification: D21F,D21G,Y10S

Abstract:
A method for controlling a cross-direction profile of at least one property of a paper web manufactured by a paper machine, comprising the steps of:feeding at least two different feed streams to a first headbox to form a pulp suspension in the first headbox, each of said feed streams containing feedstuffs for the paper to be manufactured suspended in aqueous solution, the first headbox having a plurality of cross-machine feed zones, each of said feed zones being supplied by said at least two feed streams,regulating the supply of said at least two feed steams to each of said feed zones independent of the supply of said at east two feed steam to other of said feed zones in the first headbox by means of a first feed zone regulating system, said first feed zone regulating system comprising a plurality of actuators each associated with a respective one of said feed zones, each of said actuators being arranged to vary the supply of said at least two feed streams into the respective one of said feed zones whereby a cross direction profile can be controlled,discharging the pulp suspension from the first headbox to form the web,measuring the cross direction profile of the at least one property of the web at a location downstream of the first headbox once the web is formed and generating a first measurement signal based thereon,directing the first measurement signal to a control system for controlling the first feed zone regulating system,measuring a property of at least one of the feedstuff in said at least two feed streams at a location upstream of the first headbox and generating a second measurement signal based thereon,directing the second measurement signal to the control system, andforming control signals for the first feed zone regulating system in the control system based on said first and second measurement signals and setpoint values of the at least one property of the web and directing the control signals to the first feed zone regulating system to thereby regulate each of said actuators to vary the supply of said at least two feed streams into the respective one of said feed zones.