Froth Regime Research Articles

Gas-liquid interfacial area and liquid-phase mass transfer coefficient in sieve plate columns without downcomer operating at high gas velocities.

Experiments were performed to investigate the gas–liquid interfacial area and the liquid-phase mass transfer coefficient of a two-phase dispersion on sieve plates with hole diameters of 4–12 mm and with free areas of 5.5–50.4% without downcomer. Operation was carried out at high gas velocities using cobalt-catalyzed oxidation of aqueous sodium sulfite solution with air.The two-phase dispersion showed froth regime and transition regime, which is called partially developed spray regimes/mixed froth regimes, depending on the gas velocities. The gas–liquid interfacial area of the two-phase dispersion in the froth regime is influenced by the free area of the plate, whereas no effect of free area is found in the transition regime. The correlations of interfacial area for each regime are given on the basis of the correlation obtained by Zuiderweg under a gas–liquid cross-current condition. Empirical equations for the Sherwood number based on liquid depth are obtained. Using the results of the interfacial area and the mass transfer coefficient, the mass transfer volumetric coefficient can be predicted.

Froth characteristics of shallow bubble columns with sieve plates

Radial profiles of gas holdup, liquid circulation and equivalent clear liquid height in the froth regime were measured in a shallow bubble column with Correlations for radial profiles of gas holdup in the middle region, which is one of three axial regions in the froth, and for mean values of equivalen

Entrainment from sieve trays in the froth regime

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEntrainment from sieve trays in the froth regimeHenry Z. Kister and Joe R. HaasCite this: Ind. Eng. Chem. Res. 1988, 27, 12, 2331–2341Publication Date (Print):December 1, 1988Publication History Published online1 May 2002Published inissue 1 December 1988https://doi.org/10.1021/ie00084a018RIGHTS & PERMISSIONSArticle Views332Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Separated two‐phase flow and basaltic eruptions

Fluid dynamical models of volcanic eruptions are usually made in the homogeneous approximation where gas and liquid are constrained to move at the same velocity. Basaltic eruptions exhibit the characteristics of separated flows, including transitions in their flow regime, from bubbly to slug flow in Strombolian eruptions and from bubbly to annular flow in Hawaiian ones. These regimes can be characterized by a parameter called the melt superficial velocity, or volume flux per unit cross section, which takes values between 10−3 and 10−2 m/s for bubbly and slug flow, and about 1 m/s for annular flow. We use two‐phase flow equations to determine under which conditions the homogeneous approximation is not valid. In the bubbly regime, in which many bubbles rise through the moving liquid, there are large differences between the two‐phase and homogeneous models, especially in the predictions of gas content and pressure. The homogeneous model is valid for viscous lavas such as dacites because viscosity impedes bubble motion. It is not valid for basaltic lavas if bubble sizes are greater than 1 cm, which is the case. Accordingly, basaltic eruptions should be characterized by lower gas contents and lower values of the exit pressure, and they rarely erupt in the mist and froth regimes, which are a feature of more viscous lavas. The two‐phase flow framework allows for the treatment of different bubble populations, including vesicles due to exsolution by pressure release in the volcanic conduit and bubbles from the magma chamber. This yields information on poorly constrained parameters including the effective friction coefficient for the conduit, gas content, and bubble size in the chamber. We suggest that the observed flow transitions record changes in the amount and size of gas bubbles in the magma chamber at the conduit entry.

EFFECT OF SPRAY MIXING ON TRAY EFFICIENCY I. One Dimensional Mixing

Abstract The usual models for predicting the effect of liquid mixing assume a diffusion model as is reasonable for the foam and froth regimes. Here a one-dimensional spray regime model is developed with finite spray “throw,” allowing for inlet and outlet conditions and the effect of spray mixing on tray efficiency is evaluated. The extension to less restricted models is indicated.

Film Thickness in Gas-Liquid Two-Phase Flow : 1st Report, Effect of a ring type obstacle inserted into tube

Effects of a flow obstacle are examined on the film thickness in gas-liquid two-phase upward flow belonging to slug, froth and annular flow regimes. In this experiment, a ring type obstacle is employed as the obstacle, and time varying holdup is measured by means of the constant electric current method at eight cross sections near the obstacle. Discussions are made mainly on the minimum film thickness determined by the measured holdup. Whether the obstacle is inserted or not makes essential difference in the process of changing film thickness. Values of minimum film thickness for the upstream zone of the obstacle take minima at rather small air velocities and are reduced to approximately a tenth as large as those without obstacle. Minimum film thickness in the downstream zone decreases monotonously with air velocity.

The prediction of distillation plate efficiencies from froth properties

A compound optical probe is described which is used to determine the distribution of bubble sizes and velocities when liquids are distilled on sieve trays in the froth regime. It is shown how the plate efficiencies may be thereby evaluated by thus taking into proper account the derived distribution of vapour residence times and mass transfer coefficients. The results are seen to agree with published data. Froth properties for several boiling liquids on two sieve plates are reported.

On the hydrodynamics of sieve plates without downcomers.: II. A model of plate operation and the phenomenon of multiplicity of steady state

A simplified statistical model of the plate operation in the homogeneous froth regime is presented. The model is based on the previously determined statistical properties of the pressure drop across the dispersion 1. Equations are proposed which enable the evaluation of the equilibrium liquid hold-up in terms of the flow rates and plate geometry. The equations also predict the fractions of the free area associated with the gas flow, the liquid flow and the blocked area. The model contains a parameter which was experimentally determined and correlated. The phenomenon of occurrence of two steady states corresponding to two different equilibrium liquid hold-up values, for the same gas and liquid flow rates, was also investigated, and the regions of its occurrence determined. The corresponding states were shown to belong to different regimes and the occurrence of either state to depend on the path followed to reach the steady state.

Regimes of bubbling and jetting from submerged orifices

Operation of single submerged orifices has been shown experimentally to divide into six distinct regimes according to liquid depth and gas velocity. These regimes were characterised by analysis of high speed cine photography, gas supply chamber pressure pulsations, and liquid entrainment. The various single hole regimes may be related to the several regimes known to arise on operating distillation plates. In particular, bubbling has been found to occur for a single hole over part only of the operating conditions investigated, and jetting over the rest. This change is thought to be a principal factor in the difference between the industrially important froth and spray regimes on distillation plates.