The fate of nitrogen in the chemical recovery process in a kraft pulp mill. Part III: The effect of some process variables

M Kymalainen, M Holmstrom, M Forssen, Mikko Hupa

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    Abstract

    The effects of some process variables on the fate of N in the chem. recovery cycles of pulp mills were studied.  The general picture of the relative flows of wood N in the cycle was the same for both hard and soft woods.  However, the wood species was of significance for the N concns. in the cycle as well as for the level of NOx emissions from the boiler.  The different ways to handle secondary condensates caused some minor changes in the routes of N in the cycle.  The addn. of bio-​sludge (∼0.5 wt.​% of black liquor solids) to black liquor in the middle of the evapn. plant increased the N content of liquor by ∼30​%.  However, this addn. and the feed of the high-​concn., low-​vol. gases and MeOH to the recovery boiler did not result in any change in the share of the smelt N of the liquor N or in any increase in the levels of NOx emissions in the boiler.
    Original languageUndefined/Unknown
    Pages (from-to)317–324
    Number of pages8
    JournalJournal of Pulp and Paper Science
    Volume27
    Issue number9
    Publication statusPublished - 2001
    MoE publication typeA1 Journal article-refereed

    Keywords

    • black liquors
    • chemical recovery
    • condensates
    • hardwoods
    • kraft mills
    • nitrogen
    • nitrogen oxides
    • process variables
    • sludge
    • smelt
    • softwoods

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