Online measurement of the bubble size distribution in medium-consistency oxygen delignification

Heikki Mutikainen, Nataliya Strokina, Tuomas Eerola, Lasse Lensu, Heikki Kalviainen, Jari Käyhkö

    Research output: Contribution to journalArticleScientificpeer-review


    Progress of a new imaging-based measurement of oxygen bubble size was continued by developing anautomated method for bubble detection from image data. The imaging application was found to be able tomeasure oxygen bubble size in mill conditions when using imaging apparatus connected to the sampling valveafter the first oxygen stage mixer in a Finnish softwood kraft pulp mill. This appears to be the first time thatbubble size distribution has been measured in a mill-based oxygen delignification process. Mixer rotor speedhad a clearly measurable effect on the oxygen bubble size distribution in the pulp suspension at the windowof the imaging assembly. The volumetric average bubble size with mixer rotor speed 890 rpm was 0.064 mm while with mixer rotor speed 1380 rpm it was 0.037 mm. The automated method estimated bubble volumesreasonably well, enabling further development of the online measurement application.
    Original languageEnglish
    Pages (from-to)159-164
    Number of pages6
    JournalAppita Journal
    Issue number2
    Publication statusPublished - 2015
    Publication typeA1 Journal article-refereed

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