METHOD AND DEVICE FOR MEASUREMENT OF THE RETENTION PROFILE AND FOR CONTROL OF THE RETENTION IN A PAPER/BOARD MACHINE

摘要

The invention concerns a method and a device for measurement and regulation of the retention profile of the web in a paper/board machine. In the method, from the white water drained from the web through the wire in the wire part, samples are taken by means of a sample collecting device (20) from a number of points in the cross direction of the web, preferably at uniform distances, the samples that were taken are analyzed by means of an analyzer (15), a retention profile is formed out of the measurement results, and the retention profile thus formed is used for controlling the paper machine. The device for measurement and regulation of the retention profile comprises means (15, 20, 21, 22, 23) for measurement of the retention profile across the web width from different points of width of the web, and the headbox (10) comprises ducts (A1...An) passing to different points of width of the headbox so as to pass a flow of liquid that contains a retention agent in the headbox of the paper or board machine into connection with the stock flow so as to regulate the retention profile across the web width. The ducts (A1...An) comprise, in their connection, a valve construction (V1...Vn) for regulation of the amount of retention agent into the flow moving in the duct (A1...An), the regulation of the valves (V1...Vn) taking place on the basis of the measurement data obtained from measurement of the retention profile.