Cloud height in stirred tanks: Identification of limitations and clarification of the definition

Date

2023-02-01

Author

Altıntaş, Ezgi
Ayrancı Tansık, İnci

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Cloud height is known as the height of the interface that forms between liquid-rich and solid-rich parts of a stirred tank at high solids concentrations. Formation of cloud height is undesired as mixing between the two parts is poor. This poses a significant problem for solid catalyzed reactions as the liquid-rich part is unreacted reactant. To eliminate the cloud height, first, its definition must be clarified and the conditions under which it occurs must be determined. The current definition of the cloud height does not contain the limits of two parameters that significantly affect formation of the cloud height: solids concentration (XV) and impeller speed (N). The definition is also not clear and sufficiently detailed to be applied accurately, causing different interpretations by different researchers. In this study, the aim was to clarify the definition of cloud height by determining the measurement point and the limits of XV and N on cloud height. The majority of the results were obtained in a tall tank (H = 1.5 T) agitated with a 45° down-pumping PBT. For this geometry used, the measurement point was determined as the maximum point solids can reach, which is in front of the baffle, and a meaningful cloud height data can be obtained above 2 vol % and N = 0.32 Njs.

Subject Keywords

Cloud height, High solids concentration, Impeller speed, Solid-catalyzed reactions, Solids suspension, Tall stirred tanks

URI

https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85146339477&origin=inward
https://hdl.handle.net/11511/102462

Journal

Chemical Engineering Research and Design

DOI

https://doi.org/10.1016/j.cherd.2022.12.052

Collections

Department of Chemical Engineering, Article

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Citation Formats

E. Altıntaş and İ. Ayrancı Tansık, “Cloud height in stirred tanks: Identification of limitations and clarification of the definition,” Chemical Engineering Research and Design, vol. 190, pp. 395–406, 2023, Accessed: 00, 2023. [Online]. Available: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85146339477&origin=inward.