Paper Machine Dynamics

Abstract

The effective use of modern control theory requires suitable mathematical models of the objects to be controlled and of the disturbances. Paper machines have been controlled digitally for a long time. Digital control of basis weight and moisture content is in fact one of the few examples where a digital computer and sensors form a standard package. In spite of this there are still significant gaps in our knowledge of paper machine dynamics. This paper attempts to fill a few of these. The paper is based on measurements on full scale paper machines and on a pilot plant at the Swedish Forest Products Research Laboratory (STFI). The experiments on the industrial plants were performed using control computers with appropriate instrumentation both on craft paper and newsprint machines. The experiments on the pilot plant were carried out with different fibre, clay and water mixtures. These experiments gave insight into the effect of the pulp characteristics on paper machine dynamics. Optical gauges capable of measuring low fibre concentrations were used in the experiments. This made detailed analysis of the mixing dynamics possible. The possibility of obtaining better control through the incorporation of such gauges could also be evaluated.KeywordsBasis WeightMachine SpeedFibre ConcentrationPaper MachineAverage RetentionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.