Advances in Direct Contact Evaporator Design

Direct contact evaporators are nonisothermal bubble columns where a hot gas, usually obtained by combustion, is used to heat and vaporize the solvent of a given solution that needs to be concentrated. The design of such equipment has been relied on experimental data or on a simplified method that as...

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Bibliographic Details
Published in:Chemical engineering & technology 2004-01, Vol.27 (1), p.91-96
Main Authors: Lage, P.L.C., Campos, F.B.
Format: Article
Language:English
Subjects:
Applied sciences
Chemical engineering
Design principles
Devices using thermal energy
Energy
Energy. Thermal use of fuels
Evaporation
Exact sciences and technology
Gas-Liquid systems
Heat exchangers (included heat transformers, condensers, cooling towers)
Heat exchangers and evaporators
Modeling
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Summary:Direct contact evaporators are nonisothermal bubble columns where a hot gas, usually obtained by combustion, is used to heat and vaporize the solvent of a given solution that needs to be concentrated. The design of such equipment has been relied on experimental data or on a simplified method that assumes that the gas leaves the evaporator at equilibrium with the liquid phase, giving no information about the necessary bubbling height to attain such equilibrium conditions. Recent advances in the heat and mass transfer processes during the formation and ascension of superheated bubbles together with simple mass and energy balances in the liquid phase and gas distributor system were used to develop a more detailed design procedure. The accuracy of both design procedures are compared to available experimental data in a direct contact evaporator operating in semibatch mode. The new design method agreed well with the experimental data. Direct contact evaporators are nonisothermal bubble columns where a hot gas is used to heat and vaporize the solvent of a given solution that needs to be concentrated. Several difficulties exist in the design of such equipment. In this work the recent advances in the modeling of direct contact evaporators were used to develop a more detailed design procedure. A case study for which quasi‐steady experimental data exist was used to exemplify the design procedure results of which were in very good agreement for the key design variables.
ISSN:0930-7516
1521-4125
DOI:10.1002/ceat.200401760