10 ABB Freeness and fibre morphology


measurement for quality control Online instruments that measure the characteristics of fibres in pulp can more frequently provide information than lab testing, enabling quicker corrective action to be taken by operators, leading to better productivity, says Hakan Osterholm*


laboratory, using a number of standard testing methods such as drainability (freeness), per cent of unseparated fibres (Sommerville shive) and size classification by a series of screens (Bauer-McNett). To evaluate pulp strength,


A


operators once needed to follow a laborious process of making pulp handsheets and performing destructive tests on them. By the time all these tests were complete, the pulp was often already made into paper ready to be shipped. If downward trends in pulp quality were not detected in time, many rolls of paper had


few decades ago, pulp quality in a paper mill could only be measured in a


to be rejected or downgraded because quality trends were not available in time for a correction to be made. Today, the story is very different. The evolution of online testing, automated sampling equipment and robotic testers for offline testing of both pulp and paper, combined with data historians, sophisticated control systems and emerging artificial intelligence techniques, have given the industry powerful tools to gain a much tighter control of quality while also enabling faster grade changes.


As a major supplier of laboratory and online measurement equipment – including the L&W Freeness and Fibre online


ABB’s global manager for pulp measurements Håkan Österholm


system for fibre morphology measurement in the wet end – ABB has decades of experience in supporting the evolving needs


of the industry by pioneering many measurement techniques that have helped drive quality management forward. Such expertise is evident in the ‘Fibre Guide’ book, which discusses the impacts of different fibre types and ways of processing as well as applications of fibre analysis within the industry. First developed by Lorentzen & Wettre (acquired by ABB in 2011), a second edition of the book will be published later in 2021. The new edition updates developments in this field over the last 15 years, including the use of high- resolution cameras and image analysis software that measure fibre properties much more comprehensively than the original lab tests, in a fraction of the time. Here’s a preview of some of the developments that the ‘Fibre Guide’ explores.


Figure 1: A fibrillated softwood fibre July/August 2021


Freeness measurement The original pulp freeness measurement, as measured by either the Canadian Standard Freeness test (CSF) or the Schopper-Riegler test (SR), is to a great extent a measure of the fibrillation and fines content of pulp, and simulates the drainage rate on the wet end of a paper machine. The CSF test starts with one litre of pulp suspension at a consistency of 0.3 per cent being poured into a drainage chamber. The bottom lid and the air valve on the drainage chamber are opened to start the drainage process. The


Pulp Paper & Logistics


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36