Abstract:
The present invention relates to a method and a corresponding plant for producing a fibrous web, in particular a paper web, paperboard web or tissue web. The formation of the fibrous web is defined online as a controlled variable and is held at a preselectable set-point level by way of an automatic formation control system.
Abstract:
Process and a device for detecting a change in the fiber orientation cross-direction profile of a paper or cardboard web in the manufacturing process on a paper or cardboard machine. It is recognized that a change in the fiber orientation cross-direction profile in the web is inferred or determined by way of a characteristic change in the basis weight cross-direction profile or at least one measurement quantity that correlates to it, and/or by way of a characteristic change in the basis weight in the travel direction of the web or at least one measurement quantity that correlates to it. The device includes an arrangement for detecting a change in the basis weight cross-direction profile and/or a characteristic chronological course of the change in the basis weight, which is characteristic for a change in the fiber orientation.
Abstract:
Consistency-controlled headbox for a paper machine with a common feed line for a pulp slurry, a plurality of feed line sections into which the common feed line branches, and a system for influencing the composition of the slurry flows in each of the plurality of feed line sections. At least one pulp consistency sensor is provided for sectional pulp consistency control, which may be located in a return portion of the pulp distributing line. A weight basis cross-sectional adjustment sensor and controller may also be used; with the pulp consistency controller arranged to operate with a significantly higher sensing rate than the weight basis cross-sectional adjustment controller.
Abstract:
The invention relates to a valve or throttling device for a fluid flow, and particularly a flow containing solids, like a flow of pulp suspension. The valve has the following features: A hollow body of substantially rotational symmetry, which is traversed by liquid; the hollow body has a variable passage area which is substantially of rotational symmetry; and a main direction of fluid flow which is substantially axial to the longitudinal axis of the hollow body is provided in the hollow body. A liquid feed to the passage area is provided so that a component of rotation around the direction of the main stream is added to the liquid with reference to the direction of the main stream.
Abstract:
The invention concerns a mixing system for mixing two liquids at the inlet to the headbox of a paper machine with: an inlet line (A) for the first partial volume flow (a); an inlet line (B) for the second partial volume flow (b); an outlet line (C) for the mixture volume flow (c) with the flow resistance (W); a mixing angle (.alpha.) with the inlet line (A) and the inlet line (B); a main flow angle (.beta.) between the inlet line (A) and outlet line (C); a valve (S) installed in the inlet line (B) for control of the partial volume flow (b). The mixing angle (.alpha.) is selected so that the mixture volume flow (c) remains constant, independent of the partial volume flow (b).
Abstract:
Process for conditioning a circulating felt belt of a machine, pipe suction apparatus and traversing pipe suction apparatus therefor, the process including performing a zonal conditioning of a plurality of zones across a width of the felt belt by measuring at least one of, fibrous material web cross direction profile; felt belt cross direction profile; and permeability of the felt belt across the width of at least one of the web and the belt. The felt belt is conditioned depending on measuring results obtained for a respective zone. The pipe suction apparatus includes a ceramic body extending at least essentially across the entire width of the felt belt, the ceramic body being provided with a slotted surface by way of which the felt belt is subjectable to vacuum, with a respective effective amount of slotted surface being zonally variably adjustable by way of movable tongues.
Abstract:
The invention relates to a closed-loop control device and a method for the control of the cross-machine and/or machine direction profile of at least one quality feature in the paper manufacturing process with the aid of two sensors. The first sensor picks up a first measured signal of the cross-machine and/or machine direction profile of a first quality feature of the paper web produced. A second sensor picks up a further measured signal. The further sensor is suitable for picking up a quality feature that differs from that picked up by the first sensor, or measures the first quality feature. One or both sensors traverse the web separately. The sensors act through a controller on actuators leading to the feed line or lines for the suspension leading to the flowbox of the machine for controlling thereby the first quality feature of the process.
Abstract:
A process for producing a paper web having an essentially flat basis weight cross-machine profile and for simultaneously producing an essentially flat breaking length ratio cross-machine profile. This is achieved in that the lay of the fibers is deliberately influenced with a knowledge of shrinkage behavior. Techniques for respective sectional adjustments in the cross-machine direction are described.
Abstract:
A headbox of a paper or board machine having an inlet, a distributor for feeding stock suspension to be distributed over the machine width into the inlet. A turbulence generator downstream of the distributor has a hydraulic diameter of less than 17 mm in the downstream end region. The hydraulic diameter is the diameter of individual channels through the turbulence generator. The turbulence generator has channels or plates that define several channels, each in accordance with the desired hydraulic diameter. Dimensions of the hydraulic diameter are disclosed. The turbulence generator has lands at the downstream end. The land area ratio is disclosed. A nozzle or the like downstream of the turbulence generator introduces the stock suspension over the machine width to a wire or wires of the next section.
Abstract:
A multi-layer headbox for the production of a multi-layer web of paper has, for instance, three flow planes (I, II, III), each having a pulp feed device (1.1, 1.2, 1.3). In each flow plane a turbulence generator (3) is provided which opens into a nozzle (4). In it there are two plates (5.1, 5.2) which keep two neighboring streams of slurry separate from each other up to the region of the exit slot (8). Each plate is developed as a flexurally soft plate of plastic, the downstream end of which is metal and has a thickness S of at most 0.3 mm. The plastic and metal have a different in coefficients of thermal expansion of