Continuous in-line kappa measurement system

Abstract

A system for the continual, real-time, in-situ generation of a Kappa number used by a process control system to control the delignification of papermaking pulps that includes injecting broad-spectrum light energy from a light energy source into the pulp and collecting the resultant reflected light energy from a near-and a far-light collector. The reflected light energy collected by the light collectors is analyzed by associated near- and far-light analyzers that generate analog output signals representing the intensity of selected wavelengths of light energy received by the light collectors. An included feedback arrangement conducts the light energy emitted by the light source to a location proximate the point of injection and then to an associated light analyzer that generates analog output signals representing the intensity of the light energy emitted by the light source in selected wavelengths. The output signals from the near-, far- and feedback-light analyzers are transmitted to a measurement processing system that converts the analog signals to digital signals and passes the signals to a measurement computer. The measurement computer, using preprogrammed algorithms, processes the received reflectance output signals along with previously-stored coefficient values that represent a model of the delignification or bleaching process, and along with configuration data, generates an output signal representing a Kappa number representation. The output signal from the measurement computer is converted by an input/output device into a signal form acceptable by the process control system, where it is used to control the delignification process in accordance to the Kappa number representation.