http://bioprocesos.unq.edu.ar/Biopro%20II/Paper%20escalado.pdf

Bioreactor scale-up and oxygen transfer rate in microbial processes: An overview

A good knowledge of the relationship between the two-phase countercurrent flow of a packed mass transfer column is essential for the design of rectification, absorption and desorption columns. Based on a physical model the authors describe their updated equations for calculating gas and liquid side mass transfer coefficients, pressure drop of dry or irrigated random and structured packings, their loading and flooding points as well as their liquid holdup. Based on one of the largest experimental databases in the world, the calculated results give only small deviations from the database

Prediction of Mass Transfer Columns with Dumped and Arranged Packings

Property impacts on Carbon Capture and Storage (CCS) processes: A review

Mass-transfer correlations developed during the last several decades for packed column used for industrial fractionation, adsorption, etc. are reviewed. Theoretical basis and applicability of the reviewed correlations are discussed and compared concisely. Some dominant correlations and their parameters, as well as some considerations for further improvement, are also summarized and discussed.

Review of Mass-Transfer Correlations for Packed Columns*

Theoretical Prediction of Gas-Liquid Mass Transfer Coefficient, Specific Area and Hold-Up in Sparged Stirred Tanks

Countercurrent-flow columns are widely used in production processes in the chemical industry and their application in ecological engineering is of increasing importance. A theoretical model is presented here that allows mass transfer to be described in terms of packing geometry and physical properties which influence the gas-liquid or vapour-liquid systems in absorption, desorption and rectification columns. The relationships derived from the model can be applied to all countercurrent-flow columns, regardless of whether the packing has been dumped at random or arranged in a geometric pattern.

Predicting mass transfer in packed columns

The correct choice of packing is of decisive importance for optimum process efficiency in the operation of two-phase countercurrent columns. An important criterion for this choice is the pressure drop in the gas flow. Theoretical relationships are derived for calculating the pressure drop in beds with dry and trickle packings. It has been demonstrated by comprehensive experiments that these relationships allow the pressure drop to be determined more accurately than by previous methods. The experiments were performed at the Department of Thermal Separation Processes of Bochum University on 54 different packed beds, using 24 different systems.

Modelling of pressure drop in packed columns

Up to now, the only equations that were known for calculating mass transfer during two-phase countercurrent flow in packed columns were those that apply to the range extending up to the loading point. The gas and liquid streams flow separately through the column below but not above this point. Above it, the shear stress in the gas stream supports an increasing quantity of liquid in the column, with the result that the liquid holdup greatly increases. Finally, at the flood point, the liquid accumulates to such an extent that column instability occurs. Mass transfer in this upper loading range can be described if these fluid dynamic relationships are taken into consideration. The algorithm that is presented here for its prediction is based on theoretical and experimental studies.

Fluid dynamics and mass transfer in the total capacity range of packed columns up to the flood point

We present the determination of liquid hold-up in gas/liquid two-phase countercurrent columns filled with random or structured packings. The equations resulting from the established physical relationships are verified against the values for liquid hold-up determined experimentally on 56 different column packings and 16 gas/liquid systems. The experimental and calculated results agree well, with only slight deviations. This also applies to the range between the loading and flooding points for two-phase countercurrent flow

A physical model for the prediction of liquid hold-up in two-phase countercurrent columns

Raschig Super-Rings are well-established in the field of rectification and absorption. Instead, the efficiency of these packings in liquid-liquid extraction was not investigated till now. The application of Raschig Super-Ring No. 0.3 and Raschig Super-Ring No. 1 packings in unpulsed liquid-liquid extraction columns of diameters DN 80 and DN 150 is investigated with respect to flooding point and efficiency. As a comparative study, 15-mm and 25-mm Pall-Ring packings are used. The hydrodynamic studies indicate that the Raschig Super-Ring offers a 9–10 % higher load capacity compared to the Pall-Rings. In addition, the mass transport investigations performed using the test system toluene/acetone/water reveal that the height of transfer units (HTU) for the Raschig Super-Ring No. 0.3 is higher than for the comparable 15-mm Pall-Ring. On average, the achieved difference of the HTU unit is 0.26 m.

Michael Schultes

Papers

Predicting mass transfer in packed columns

Modelling of pressure drop in packed columns

Fluid dynamics and mass transfer in the total capacity range of packed columns up to the flood point

A physical model for the prediction of liquid hold-up in two-phase countercurrent columns

Raschig Super‐Ring Operating Characteristics in Unpulsed Liquid‐Liquid Extraction Columns