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Hydrodynamics of the flow transition from a bubble column to an airlift‐loop reactor
Author(s) -
Verlaan Paul,
Vos JanChris,
Van T Riet Klaas
Publication year - 1989
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.280450204
Subject(s) - flow (mathematics) , mechanics , plug flow , flow velocity , thermodynamics , volumetric flow rate , bubble , physics , chemistry
Abstract The hydrodynamics of an airlift‐loop reactor (ALR) and a bubble column (BC) were studied in the same reactor unit. When the liquid circulation in the ALR was impeded gradually in order to obtain a BC mode of operation, there was a transition flow regime inbetween that of the ALR‐type flow and the BC‐type flow. In the BC the heterogeneous flow was represented by an instationary circulatory flow pattern and characterized by a liquid circulation velocity. The liquid flow in the ALR was represented by a drift‐flux model. In the transition flow regime, hydrodynamic calculations based on the plug‐flow behavior of an ALR appeared to be valid up to a certain defined value of the total gas‐liquid flow rate. To distinguish between BC and ALR flow characteristics, a simple criterion is proposed, qualifying that the distinction between both flow patterns is determined by the superficial liquid velocity and the liquid circulation velocity. If the latter velocity exceeds the superficial liquid velocity a hydrodynamic transition will occur from a uniform ALR type of flow to a heterogeneous BC type of flow. The criterion coincides with an empirical power law function in which the liquid velocity is given as a function of the gas velocity. The values of the power‐law coefficients depended on the characteristics of the two‐phase flow. The change in value cohered with the onset of a change in the flow pattern.