Hollow fiber membrane contactors

Supercritical extraction and fractionation of natural matter is one of the early and most studied applications in the field of supercritical fluids In the last 10 years, studies on the extraction of classical compounds like essential and seed oils from various sources: seeds, fruits, leaves, flowers, rhizomes, etc, with or without the addition of a co-solvent have been published Supercritical extraction of antioxidants, pharmaceuticals, colouring matters, and pesticides has also been studied The separation of liquid mixtures and the antisolvent extraction are other processes that can perform very interesting separations Mathematical modelling has also been developed and refined for some of these processes The objective of this review is to critically analyze traditional and new directions in the research on natural matter separation by supercritical fluids extraction and fractionation

Supercritical fluid extraction and fractionation of natural matter

Methods and apparatus relate to recovery of carbon dioxide and/or hydrogen sulfide from a gas mixture. Separating of the carbon dioxide, for example, from the gas mixture utilizes a liquid sorbent for the carbon dioxide. The liquid sorbent contacts the gas mixture along asymmetric hollow-fiber membranes that enable transfer of the carbon dioxide from the gas mixture to the liquid sorbent.

Hollow-fiber membrane contactors

Modelling reactive distillation

Supercritical CO2 extraction of essential oils is one of the most widely discussed applications in the supercritical fluid literature. Nevertheless, a comprehensive overview of the analytical, processing and modeling aspects has never been attempted. This is partly due to the difficulties involved in isolating essential oils from the other products which supercritical CO2 can dissolve. Moreover, only a limited number of studies provide quantitative data on the parameters governing this process.

In this review, solubility data on pure compounds belonging to essential oils are analyzed. Processes proposed to isolate and fractionate essential oils by supercritical CO2 and the corresponding modelling aspects are discussed critically.

Supercritical fluid extraction and fractionation of essential oils and related products

This is the second part of a two-part paper dealing with the fluid mechanics and mass transfer in structured packings for distillation column service. The first part elucidated pressure drop, flooding, and liquid holdup. The second part covers the generation of effective interfacial area and provides a general correlation for predicting the mass-transfer efficiency as a function of surface type, packing geometry, phase flow conditions, and fluid properties. The mass-transfer model has been tested against a variety of commercial structured packings, for distillation pressures ranging from 0.33 to 20.4 bar. In all cases the fit of the data is excellent, with the possible exception of the highest pressures, where additional factors of axial mixing appear to have an effect.

Distillation Columns Containing Structured Packings: A Comprehensive Model for Their Performance. 2. Mass-Transfer Model

A mechanistically-based model has been developed to aid the analysis and design of distillation columns containing structured packings of the corrugated plate type. The model encompasses the important, and related, parameters of liquid holdup, pressure drop, flooding, and mass-transfer efficiency. Since it deals with the countercurrent contacting of liquid with gas or vapor, the model may also be applied to absorption or stripping processes. The model is developed from a consideration of the interaction of falling liquid films with upflowing vapors and thus takes into account the flow and physical property characteristics of the systems as well as geometric variables such as corrugation angle and surface enhancement. In this paper (part 1) the model is developed and applied to several sets of liquid holdup and pressure drop experimental data, including new data provided by the authors. The second paper in the series will deal with mass-transfer characteristics, with the model being shown to be dependent on the hydraulic aspects described in part 1. The information provided in these papers should have direct application to new designs, retrofits, or optimization of existing equipment.

Distillation columns containing structured packings: a comprehensive model for their performance. 1. Hydraulic models

On met au point de nouvelles equations pour refleter l'efficacite des donnees transferts de masse pour les garnissages en toiles metalliques lorsque l'on se trouve dans les conditions de distillation

Mass transfer in gauze packings

Distillation has been used for separating liquid mixtures for more than two thousand years, and it continues to be the most widely used separation technique in key industries throughout the industrialized world. Although the basic principles have remained the same since the days of the ancient Egyptians, new distillation and distillation control methods continue to be developed to satisfy a variety of highly specialized requirements. Distillation Principles and Practice is an indispensable working resource for distillation technicians working in the oil, petrochemical, chemical, and pharmaceutical industries.

James R. Fair

Papers

Distillation Columns Containing Structured Packings: A Comprehensive Model for Their Performance. 2. Mass-Transfer Model

Distillation columns containing structured packings: a comprehensive model for their performance. 1. Hydraulic models

Mass transfer in gauze packings

Distillation: Principles and Practices

General model for prediction of pressure drop and capacity of countercurrent gas/liquid packed columns