Valmet Corporation

Matti Luontama

Juha Kaihovirta

Pekka Pakarinen

Harri Mustonen

Pasi Ahonen

Ville Korhonen

Jaakko Kallioniemi

A feedback-connected on-line regulation system for a headbox of a paper or board machine. The headbox includes a flow duct for stock suspension or separate flow ducts placed one above the other, each flow duct extending from an inlet header of the headbox into its slice channel. A stock suspension jet is discharged from the slice opening of the slice channel onto the forming wire or into the forming gap formed between forming wires. The regulation system includes a regulator unit and a set value unit. Measurement values are passed from the headbox system to the regulator unit and from the regulator unit, control values are obtained for controlling the actuators of the headbox system. The regulation system also includes an on-line If arrangement for measurement of the dried paper web or the paper web to be dried, and includes measurement of the distribution of fibers in the plane of the paper web. By means of the measurement signal obtained from this measurement arrangement, the actuators of the headbox are controlled by feedback so as to achieve a distribution of fiber orientation and a corresponding MD/CD ratio of strength in accordance with the set value in the paper web to be produced under control of the regulation system.

Regulation system and method in a paper machine

A method for controlling the curl of paper in which steam treatment and/or moistening of the paper web is/are carried out after the calendering process being performed in the calender. In processes in which calendering is not employed, the curl is controlled in connection with a machine reel-up or in process steps carried out after the machine reel-up. A paper or board machine applying the method includes a headbox, a former, a press, a dryer section and steam boxes, moistening devices, an IR dryer and/or equivalent curl control devices. The steam boxes, moistening devices, IR dryers and/or equivalent curl control devices for the control of the curl are arranged after the calender or, if no calender is employed, in connection with a machine reel-up or a finishing process carried out after the machine reel-up.

Method for controlling the curl of paper and a paper or board machine

A dry end of a paper machine and a method for drying paper in which a paper web to be dried is passed from a press section of the paper machine into a forward dryer section including only single-wire groups with normal single-wire draw. The web is dried from the side of its bottom face in the dryer groups in the forward dryer section. From the forward dryer section, the web is passed into a finishing section in which the web is coated/surface-sized by a coating/surface-sizing device and then dried in an after-dryer by passing through at least one dryer group that applies a normal single-wire draw. Thereafter, the web is calendered and passed to a reeling station. Curling of the web is controlled by the operation or construction of components and/or by assemblies and combinations formed out of these components provided in connection with the forward dryer section and/or the finishing section.

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Jyvaskyla, Finland

Matti Luontama