Statistische Extinktionsmethode zum Inline-Monitoring von Partikelprozessen

Abstract For inline monitoring of particle processes two optical measurements devices based on statistical extinctions methods are developed in this work. The Statistical Extinction Sensor (SE-Sensor) determines an average particle size and a particle concentration. Therefore the time dependent transmission of a light beam through the particle system is measured. A mean particle size and a particle concentration are calculated by an optimized statistical extinction method (PGV-SE-Method). Both methods work contactless and do almost not influence the process in case of an appropriate measuring volume. The transmission signal of a light beam is influenced by a number of effects which are not taken into account by deriving the statistical extinction method. These effects are, for example, boundary layer and overlapping effects as well as effects due to the polydispersity of particle collectives and the aperture of the sensor. These effects superpose each other and effects caused by the measurements uncertainty of the sensor. Measurements do not facilitate a separate investigation of the influence of these effects. The simulation of transmission signals of light beams through particle systems offers to interrupt single effects. This facilities to investigate the influence of these effects and the transmission signals. For this purpose, a program is developed and implemented in Matlab, which calculates the time dependent transmission signal through a moving particle system with freely definable properties. With this program, the influence of these effects is investigated and a mutual interaction of these effects is observed. The SE-Function, which defines the correlation between the mean value and the root mean square deviation of the transmission signal on one side and the mean particle size and the particle concentration on the other side, is determined empirically by simulating the extinction of light beams through many different monodisperse particle systems. This SE-Function takes the influence of boundary layer and overlapping effects into account. Effects through the aperture of the detector optic are taken into account by calculating appropriate extinction coefficients. Effects due to the polydispersity of the particle system cannot be taken into account by SE-Function.