Advances in Direct Contact Evaporator Design

Lage, Paulo Laranjeira da Cunha; Campos, Flavio Barboza

doi:10.1002/ceat.200401760

Cited by 14 publications

(8 citation statements)

References 10 publications

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“…As highlighted by Lage and Campos [207], though reasonable for high bubbling heights, this assumption is highly undesirable, for it turns the model insensitive to the bubbling height, one of the key design variables in a DCE. In order to maximize the vaporization rate per unit volume, the bubbling height should be chosen as the smallest value necessary to extract all the available energy from the inlet gas.…”

Section: Modeling and Simulationmentioning

confidence: 96%

Gas-Liquid Direct-Contact Evaporation: A Review

Ribeiro¹,

Lage²

2005

Chem. Eng. Technol.

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Gas-liquid direct-contact evaporators are characterized by the bubbling of a superheated gas through the solution to be concentrated. In other words, they are nonisothermal bubble columns. Despite their simplicity of construction, these units exhibit rather complex hydrodynamics and, similar to what occurs to isothermal bubble columns, the design of such units still poses a problem. The present paper reviews the literature regarding this kind of equipment, addressing both experimental studies and modeling efforts. The covered issues include classic and potential applications, bubbling regimes, gas holdup and bubble size distributions, as well as mathematical models proposed for simulating the unit. Additionally, pertinent literature on isothermal bubble columns is also discussed. Recommendations are made for future research.

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Section: Modeling and Simulationmentioning

confidence: 96%

Gas-Liquid Direct-Contact Evaporation: A Review

Ribeiro¹,

Lage²

2005

Chem. Eng. Technol.

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“…High levels of mixing are achieved by the vigorous introduction of the gas phase into the system. This often results in thermally homogeneous operation between the two phases, minimizing the likelihood of hot-spot formation at heat-exchanging surfaces. , The vigorous mixing also achieves good rates of heat and mass transfer between the two phases , and often allows the exiting gas stream to reach equilibrium with minimal contact time required between the two phases. ,, This saturated vapor is what provides the good rates of evaporation achieved by bubble columns at temperatures appreciably lower than their respective boiling points.…”

Section: Introductionmentioning

confidence: 99%

Binary Solvent Swap Processing in a Bubble Column in Batch and Continuous Modes

Roche

Jones

Glennon

et al. 2022

Org. Process Res. Dev.

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A lab-scale bubble column was investigated as an alternative means to achieve a low-temperature binary solvent swap of solutions containing pharmaceutical materials at atmospheric pressure, for batch and continuous configurations. The rate of solvent evaporation was predicted by first-principles vapor–liquid equilibrium (VLE) thermodynamic modeling and compared to experimentally achieved results. For batch configurations, evaporation rates of up to 5 g/min were achieved at gas flow rates up to 2.5 L/min (0.21 m/s superficial velocity) and temperatures up to 50 °C. This achieved 99 mol % purity of the desired solvent within three “put and take” evaporations from a 50:50 starting mixture. The evaporation rate profiles for the duration of the experiments were calculated, and the changing concentration profile was predicted within satisfactory error margins of <5%. Continuous process modeling explored a multistage equilibrium configuration and could predict the approach to attaining steady-state operation for various operating conditions. All rates of evaporation and resulting changes in solution concentration were measured, and direct comparison of model predictions fell within instrumentation error margins, as previously. This underlined the capability of the model to provide accurate representations of predicted evaporation rates and binary solution concentration changes during operation.

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“…Bubble columns have been shown to offer high rates of mass and heat transfer throughout, due to the intimate contact of the two phases and the enhanced mixing profiles provided by the bubble dynamics [11][12][13][14][15] . Also advantageous is their relative simplicity of installation, requiring no moving parts and easily introduced in most working fume hoods with suitable plumbing.…”

Section: Introductionmentioning

confidence: 99%

“…6,9,10 Bubble columns have been shown to offer high rates of mass and heat transfer throughout, due to the intimate contact of the two phases and the enhanced mixing profiles provided by the bubble dynamics. [11][12][13][14][15] Also advantageous is their relative simplicity of installation, requiring no moving parts and easily introduced in most working fume hoods with suitable plumbing facilities. Here, it is proposed that they may provide a suitable alternative to conventional evaporation operations such as large scale boilers, providing typical production CM scale rates of evaporation, which can be often <1 g/min.…”

Section: Introductionmentioning

confidence: 99%

Development of a continuous evaporation system for an API solution stream prior to crystallization

et al. 2021

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A bubble column was investigated as a method to achieve a desired and controllable rate of evaporation of a pharmaceutical solution. Applying a thermodynamic model to predict the rate of evaporation, all predicted values were observed to have accuracies within the bounds of instrumentation errors (<5% absolute). The thermodynamic model accounted for the measured effect of reduced vapor pressure caused by the dissolved solids as a function of their concentration. A general method to obtain accurate measurement of this effect is introduced and applied, improving the accuracy of model predictions. Predicting the rate of evaporation using the developed model, consistent and repeatable evaporation rates ranging from 0.7 -6.9 g/min were achieved, and errors between predicted rates and experimental ranged from 0.219% to 4.19% absolute. This demonstrates a more controllable and flexible alternative to the evaporation of process streams compared to boiling. The column was configured in a continuous mode and coupled to a downstream crystallizer (MSMPR). Using the column as a controllable concentrator, the concentration of a dilute feed stream of paracetamol in methanol was increased in a single equilibrium stage. The column demonstrated the ability to concentrate the solution in flow by 179%, delivering an output of 2 mL/min to the MSMPR. The MSMPR achieved steady-state of control, measured by offline This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as

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Advances in Direct Contact Evaporator Design

Cited by 14 publications

References 10 publications

Gas-Liquid Direct-Contact Evaporation: A Review

Gas-Liquid Direct-Contact Evaporation: A Review

Binary Solvent Swap Processing in a Bubble Column in Batch and Continuous Modes

Development of a continuous evaporation system for an API solution stream prior to crystallization

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