Consistency regulated Head-Box with a paper pulp consistency regulator

摘要

A paper-making machine headbox with pulp density regulation has: a common supply conduit(1) for the pulp suspension; many sections (2) branching from the conduit; means (3) for influencing the pulp composition of the streams in the individual sections and; at least one sensor (22) for regulating the composition in the individual sections. Also claimed is a regulator for the headbox comprising: at least one sensor (8) outside the headbox for detecting the paper web's transverse profile of weight per unit area; a controller (12) to regulate said profile and said means for influencing individual stream composition. The controller includes a pulp consistency regulator (20) in each section to form a basis for the transverse weight profile control. Also claimed is a headbox control process comprising the following steps: determination of the transverse area weight profile outside the headbox at a scanning rate, delta T; comparison of this profile with a theoretical profile stored in the controller; activating an adjuster for each section if the actual deviates from the theoretical value and undertaking the following further steps: determining pulp consistency at a suitable point in the headbox at a scanning rate, delta t; comparing actual pulp consistency with a theoretical value and; activating an adjuster for each section if actual deviates from theoretical.