Patent ID: 6328851
Filing Date: 2001-12-11
Classification: D21F,D21G,D21H,G01N,Y10S

Abstract:
A method for controlling properties of paper produced by a paper making machine, said method comprising providing a flow of paper stock, supplying the paper stock to a headbox, measuring flow of the paper stock, conveying the paper stock from the headbox to a former section in which a paper web is produced and from which white water is expelled, producing paper from the paper web, measuring properties of the paper including basis weight, combing the white water into the paper stock, adding a flow of filler to the paper stock, adding a flow of retention agent to the paper stock, the white water, the paper stock and the paper having respective amounts of ash content, said method comprising a control system including a dynamic model and control variables, said model relating the effect of the flow of retention agent and the paper stock flow on the basis weight of the paper to adjust, on the basis of said model, the basis weight by simultaneously controlling the flow of retention agent and the stock flow,the control system comprising predictor and optimization steps, in which the predictor step takes into account operating variables and said model and provides a prediction on the basis thereof, and the optimization step utilizes the prediction produced by the predictor step to optimize the control variables.