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Magazine articles
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
Magazine articles
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Li-ion Batteries are Making a Roar, Paper360º May/June 2021
Journal articles
Magazine articles
One of the World’s Most Modern Paper Mills, Paper360º May/June 2021
One of the World’s Most Modern Paper Mills, Paper360º May/June 2021
Journal articles
Magazine articles
Future-Proofing Green and Digital Growth in the European Paper Industry, Paper360º May/June 2021
Future-Proofing Green and Digital Growth in the European Paper Industry, Paper360º May/June 2021Future-Proofing Green and Digital Growth in the European Paper Industry, Paper360º May/June 2021
Conference papers
Nanocellulose Liquid Crystal Bubbles, Emulsions and Colloidal Glass, 2021 NANO Virtual Conference
Nanocellulose Liquid Crystal Bubbles, Emulsions and Colloidal Glass, 2021 NANO Virtual Conference
Conference papers
Friction behavior of tempo-oxidized nanofibrillated cellulose and its composites, 2021 NANO Virtual Conference
Friction behavior of tempo-oxidized nanofibrillated cellulose and its composites, 2021 NANO Virtual Conference
Conference papers
Application of Nanocellulose-based Composites in Salt Hydrate Phase Change Materials for Thermal Energy Storage, 2021 NANO Virtual Conference
Application of Nanocellulose-based Composites in Salt Hydrate Phase Change Materials for Thermal Energy Storage, 2021 NANO Virtual Conference
Conference papers
Benchmarking Cellulose Nanocrystals Part II: New Industrially-Produced Materials, 2021 NANO Virtual Conference
Benchmarking Cellulose Nanocrystals Part II: New Industrially-Produced Materials, 2021 NANO Virtual Conference
Conference papers
Standardizing Measurements for Cellulose Nanocrystal Particle Size Distributions, 2021 NANO Virtual Conference
Standardizing Measurements for Cellulose Nanocrystal Particle Size Distributions, 2021 NANO Virtual Conference
Conference papers
Combining tannins with cellulose nanofibrils towards functional materials, 2021 NANO Virtual Conference
Combining tannins with cellulose nanofibrils towards functional materials, 2021 NANO Virtual Conference