ABB PULP DEFECT ANALYZER - ONLINE DIRT COUNT MEASUREMENT

摘要

A pulp mill is built to produce high quality pulp for the paper industry. One of the most important quality factors for pulp is dirt count. Dirt count describes the overall dirt content of pulp. It is a standardized measurement value defined in corresponding ISO and TAPPI standards. Knowing the dirt content of pulp, particularly of recycled pulp, is important for its suitability to make fine paper. Dirt is any foreign material in pulp. Typical pulp defects include small dirt spots and shives. Most pulp defects are very small - typically less than one square millimeter. Manual inspection is carried out in reflection or transmission illumination. It is traditionally based on cut out samples, which cover only a tiny fraction of the whole bale or its whole surface area. When conducted by the principles presented in the standards for reflected light inspection, the requirements are that every tenth bale should be inspected with at least ten samples from each bale. Each inspected sample should cover at least one forth of a square meter and should be inspected on both sides. Manual inspection of such sample lots is labor consuming and error prone. Also, there can be variations in the results from one inspector to another. An automated on-line inspection system based on high sensitivity digital camera technology and advanced machine vision tools inspects the whole length of a bale with consistent and repeatable results. A reliable ABB Pulp Defect Analyzer detects and reports defects as small as 0,04 mm~2, the minimum defect size included in the standards. With the help of the applied machine vision technology the size of each defect can be determined with an accuracy of one hundredth of a square millimeter.