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The role of gas dispersion in the oxygen delignification process, TAPPI Journal May 2021
ABSTRACT: Oxygen delignification is an essential part of the pulp production process. Delignification occurs with the aid of alkali and dissolved oxygen. Dissolved oxygen is obtained by dispersing oxygen gas into the pulp suspension by using efficient mixers. Little is known about the state of oxygen gas dispersion and its effect on oxygen delignification kinetics and efficiency. This paper will present the results for the effect of gas bubble size on the performance of oxygen delignification. The results are mainly based on detailed studies made in a Finnish hardwood mill where the oxygen bubble size distribution could be altered at the feed of the reactor. An essential aspect of these studies was the use of a new continuous inline gas bubble size measurement system to simultaneously determine the bubble size distribution at the feed and top of the reactor. Information about oxygen consumption in the reactor could also be obtained through the bubble size measurements. Accordingly, these studies quantify the effect of oxygen bubble size on the kappa reduction of the pulp. The effect of different chemical factors on the oxygen bubble size is also studied.Finally, the relationship between the gas bubble size and the liquid phase oxygen mass transfer coefficient (kLa) is presented. This connects the bubble size to the kappa reduction rate. Based on the presented modeling approach and the evaluation of practical factors that are not taken into account in the modeling, it was concluded that the volumetric average oxygen bubble size should preferably be smaller than 0.2 mm in practice.The information obtained with the new gas bubble size measurement system and the presented modeling approach give a very new basis for understanding, monitoring, adjusting, and designing oxygen delignification processes.
Journal articles
A financial analysis of north american pulp, paper and packaging firms, TAPPI JOURNAL, September 1999, Vol. 82(9)
A financial analysis of north american pulp, paper and packaging firms, TAPPI JOURNAL, September 1999, Vol. 82(9)
Journal articles
Dissolving pulp from white press cuttings, TAPPI JOURNAL Apr
Dissolving pulp from white press cuttings, TAPPI JOURNAL April 2016
Journal articles
Xylanase Treatment for the Bleaching of Softwood Kraft Pulps
Xylanase Treatment for the Bleaching of Softwood Kraft Pulps: The Effect of Chlorine Dioxide Substitution, 1992 Pulping Conference Proceedings
Journal articles
Synthetic lubricant use in pulp and paper mills, TAPPI JOURNAL, November 1998, Vol. 81(11)
Synthetic lubricant use in pulp and paper mills, TAPPI JOURNAL, November 1998, Vol. 81(11)
Journal articles
Influence of cultivars, years, environment, and stem location on kenaf fiber properties, TAPPI JOURNAL, October 1998, Vol.81(10)
Influence of cultivars, years, environment, and stem location on kenaf fiber properties, TAPPI JOURNAL, October 1998, Vol.81(10)
Journal articles
Steam turbine risk assessment project: inspection and overhaul optimization of steam turbines, TAPPI JOURNAL, September 1998, Vol. 81(9)
Steam turbine risk assessment project: inspection and overhaul optimization of steam turbines, TAPPI JOURNAL, September 1998, Vol. 81(9)
Journal articles
Environmental progress at Howe Sound Pulp & Paper, TAPPI JOURNAL, September 1998, Vol. 81(9)
Environmental progress at howe sound pulp & paper, TAPPI JOURNAL, September 1998, Vol. 81(9)
Journal articles
Evaluation of internal thermophilic biotreatment as a strategy in tmp mill closure, TAPPI JOURNAL, August 1999, Vol. 82(8)
Evaluation of internal thermophilic biotreatment as a strategy in tmp mill closure, TAPPI JOURNAL, August 1999, Vol. 82(8)
Journal articles
Industry's rle in gasification commercialization: the agenda 2020 perspective, TAPPI JOURNAL, December 1999, Vol. 82(12)
Industry's rle in gasification commercialization: the agenda 2020 perspective, TAPPI JOURNAL, December 1999, Vol. 82(12)