INFLUENCE OF INTERFACIAL TENSION AND VISCOSITY ON THE BEHAVIOR OF A PACKED COLUMN IN NEAR-CRITICAL FLUID EXTRACTION
作者:
ALESH BLAHA-SCHNABEL,
ANDREAS BEYER,
BERND CZECH,
HELGA JAKOB,
HARTMUT SCHIEMANN,
ECKHARD WEIDNER,
SIEGFRIED PETER,
期刊:
Chemical Engineering Communications
(Taylor Available online 1996)
卷期:
Volume 146,
issue 1
页码: 13-31
ISSN:0098-6445
年代: 1996
DOI:10.1080/00986449608936479
出版商: Taylor & Francis Group
关键词: Density of fluids;Viscosity of fluids;High-pressure interfacial tension;Film instability;Near-critical extraction
数据来源: Taylor
摘要:
Density and viscosity of the coexisting phases and interfacial tension of the following binary systems were measured: pelargonic acid, linoleic acid, oleic acid or stearic acid as subcritical and carbon dioxide as superecritical components. Also the corresponding phase equilibria were investigated at pressures ranging from 2 to 20 MPa and temperatures from 313 K to 393 K. With increasing pressure the concentration of the supercritical component in the liquid phase increases and viscosity and liquid interfacial tension decreases. At greater activities of the dense gases the interfacial tension decreases dramatically to values less than 2 mN/m. If the pressure exceeds a certain limit, a falling film disintegrates into small droplets. The surface excess passes through a maximum at these conditions. At first appearance of instabilities on a falling film, the logarithm of the Reynolds number is a linear function of the logarithm of the film number. Independent of the type of the investigated packings, the number of theoretical stages per meter versus Hodenstein number fall all on the same curve when an extraction is carried out in the droplet regime. Also the logarithm of the capacity of a column al the flooding point versus the logarithm of the density difference between the coexisting phases is a linear function when an extraction is carried out in the droplet regime.
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