Hydrodynamic and gas phase axial dispersion in an air-molten salt two-phase system (molten salt oxidation reactor)

2005 ◽  
Vol 44 (10) ◽  
pp. 1054-1062 ◽  
Author(s):  
Yong-Jun Cho ◽  
Hee-Chul Yang ◽  
Hee-Chul Eun ◽  
Jae-Hyung Yoo ◽  
Joon-Hyung Kim
Keyword(s):  
Molten Salt ◽  
Gas Phase ◽  
Axial Dispersion ◽  
Phase System ◽  
Two Phase ◽  
Oxidation Reactor

scholarly journals Hydrodynamics and axial mixing in a packed gas-liquid column

2003 ◽  
pp. 33-48
Author(s):  
Branislava Barjaktarovic ◽  
Milan Sovilj ◽  
Svetlana Popovic
Keyword(s):  
Pressure Drop ◽  
Gas Phase ◽  
Liquid Flow ◽  
Packed Column ◽  
Packed Bed ◽  
Axial Dispersion ◽  
Gas Absorption ◽  
Phase System ◽  
Two Phase ◽  
Gas Phases

The objective of this study was to investigate the pilot-plant gas absorption packed column hydrodynamics, as well as axial mixing in the system air-water. The pressure drop and the gas phase holdup data were determined in dependence on the flow rates of gas and liquid phases. The influence of superficial velocities of liquid and gas phases on the liquid axial dispersion in a gas-liquid packed bed column (ID 15 cm) consisting of Raschig rings (15x15x2 mm) were investigated. The pressure drop was measured with a U-type manometer, connected to the bottom and the top of the working part of the column. The gas phase holdup data in the air-water two-phase system was calculated as a ratio of the gas phase volume to the total volume of the two-phase system. Axial dispersion in the water phase has been determined by examining of the distribution of residence times of a salt tracer (NaCl) in the packed bed. The tracer was injected in the liquid flow above the packed bed; samples of liquid were simultaneously taken from two sites at 1 m distance along the bed. Salt concentrations in the samples were determined by conductivity measurements. The mean residence time and the axial dispersion number were calculated by the moment method. The axial dispersion increases with an increase of liquid flow velocities and decrease of superficial air velocities.

A Developed Numerical Method for Turbulent Unsteady Fluid Flow in Two-Phase Systems with Moving Interface

2017 ◽  
Vol 14 (06) ◽  
pp. 1750063 ◽  
Author(s):  
A. M. Hegab ◽  
S. A. Gutub ◽  
A. Balabel
Keyword(s):  
Numerical Model ◽  
Gas Phase ◽  
Level Set ◽  
The Body ◽  
Phase System ◽  
Computational Domain ◽  
Two Phase ◽  
Moving Interface ◽  
Level Set Function ◽  
Gas System

This paper presents the development of an accurate and robust numerical modeling of instability of an interface separating two-phase system, such as liquid–gas and/or solid–gas systems. The instability of the interface can be refereed to the buoyancy and capillary effects in liquid–gas system. The governing unsteady Navier–Stokes along with the stress balance and kinematic conditions at the interface are solved separately in each fluid using the finite-volume approach for the liquid–gas system and the Hamilton–Jacobi equation for the solid–gas phase. The developed numerical model represents the surface and the body forces as boundary value conditions on the interface. The adapted approaches enable accurate modeling of fluid flows driven by either body or surface forces. The moving interface is tracked and captured using the level set function that initially defined for both fluids in the computational domain. To asses the developed numerical model and its versatility, a selection of different unsteady test cases including oscillation of a capillary wave, sloshing in a rectangular tank, the broken-dam problem involving different density fluids, simulation of air/water flow, and finally the moving interface between the solid and gas phases of solid rocket propellant combustion were examined. The latter case model allowed for the complete coupling between the gas-phase physics, the condensed-phase physics, and the unsteady nonuniform regression of either liquid or the propellant solid surfaces. The propagation of the unsteady nonplanar regression surface is described, using the Essentially-Non-Oscillatory (ENO) scheme with the aid of the level set strategy. The computational results demonstrate a remarkable capability of the developed numerical model to predict the dynamical characteristics of the liquid–gas and solid–gas flows, which is of great importance in many civilian and military industrial and engineering applications.

DDTW-A Method for Gas Reservoir Evaluation Using Dual Wait-Time NMR and Density Log Data

2001 ◽  
Vol 4 (04) ◽  
pp. 289-296
Author(s):  
Holger F. Thern ◽  
Songhua Chen
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Aqueous Phase ◽  
Wait Time ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Proton Density ◽  
Phase System ◽  
Two Phase ◽  
Gas Properties

Summary Accurate estimates of porosity, fluid saturations, and in-situ gas properties are critical for the evaluation of a gas reservoir. By combining data from a dual wait-time (DTW) nuclear magnetic resonance (NMR) log and a density log, these properties can be determined more reliably than by either of the data alone. The density and NMR dual wait-time (DDTW) technique, introduced in this paper, is applicable to reservoirs where the pore-filling fluid consists of a liquid phase and a gas phase. The low proton density of the gas phase causes a reduction in the NMR signal strength resulting in underestimation of the apparent porosity. The polarization for different wait-times depends on the spin-lattice relaxation time of each fluid and may cause additional NMR porosity underestimation. The density log, on the other hand, delivers a porosity that is overestimated because of the presence of a gas phase. These data, together with known correlations for gas properties, yield a robust approach for the gas-zone porosity, f, and the flushed zone gas saturation, Sg, xo. DDTW also derives gas properties including the in-situ gas density, ?g, as well as the two NMR-related properties, hydrogen index, IH, g, and spin-lattice relaxation time, T1g. Two field examples illustrate the method, and an error propagation study shows the reliability of the technique. Introduction NMR well logging yields information about fluid and rock properties. Depending on the goal of the investigation, various NMR measurement procedures are employed. Differences in the acquisition pulse sequence - including the wait-time (tw) between the echo-train measurements - characterize these procedures. Common evaluation techniques estimate different petrophysical properties, such as incremental and total porosities or movable (fm, NMR) and irreducible (fir, NMR) fluid fractions. More sophisticated methods separate the response of multiple fluids for hydrocarbon typing and saturation estimation. DTW NMR Log. Water as the wetting phase is dominated by surface relaxation and usually has a shorter T1 than hydrocarbons. DTW NMR uses the T1 contrast between aqueous fluid and hydrocarbon phases to achieve partial or full polarization for different fluid phases. The DTW log acquires two echo trains with a long (tw, L) and a short (tw, S) wait-time in a single pass; tw, L is chosen to fully polarize both water and hydrocarbon, and tw, S is sufficiently long to fully polarize the water fraction, while the hydrocarbon fraction is only partially polarized, causing porosity underestimation. An interpretation technique for DTW NMR data - used mainly qualitatively - is the differential spectrum method (DSM).1 A successful quantitative evaluation technique is the time domain analysis (TDA).2 Both techniques require the calculation of either differential echo signals or differential T2 spectra, where the spectra are derived from echo-train data by inversion. The differential signals are significantly weaker than the original signal, and the noise level increases because the incoherent noise of the echo trains is added. Differential data, therefore, are unfavorable in terms of their signal-to-noise ratio (SNR). SNR often limits the applicability of evaluation techniques that are based solely on NMR data. Particularly when coupled with low hydrocarbon saturation and the low proton density of a gas phase, poor SNR is the limiting factor in estimating accurate reservoir properties. Density Log. The density log provides a bulk density, ?b, of the investigated formation. Additional information about the density of the rock matrix and formation fluids determines the density porosity fr. An established method to evaluate gas-bearing formations combines the apparent porosities provided by the density and the neutron logging tools. For many data sets, however, this method yields only semiquantitative results because of the strong influence of rock mineralogy on the neutron measurement. Theory The porosity of clean formations bearing only liquid-phase components can be accurately quantified by either the NMR or the density logging tool. However, the tool's responses are significantly altered by the presence of a gas phase, causing the estimated porosities to deviate from the formation porosity. Three main effects cause the deviation.Low IH, g decreases the NMR porosity.Partial polarization Pg<1 decreases the NMR-derived porosity, if the wait-time between the NMR measurements is insufficiently long.Low ?g increases the density porosity. The characterization of a hydrocarbon gas by three key properties, ?g, IH, g, and T1g, effectively quantifies these effects. DTW NMR Log. In a two-phase system with one gas and one liquid phase, the total NMR porosity ft, NMR is expressed byEquation 1 where the first term on the right side describes the contribution of the gas phase and the second term describes the contribution of the liquid phase. The polarization P (with P?[0,1]) quantifies the reduction of the NMR signal caused by underpolarization. The termsEquation 2Equation 3 describe the polarization of the liquid and gas phases, respectively. Some approximations can be made for common reservoir conditions.IH, l is close to 1 for an aqueous-phase liquid and most oleic-phase liquids. In the presence of a light liquid hydrocarbon, its value can be slightly smaller (IH, l =0.8-1).If tw 3T1, the polarization is nearly unity. Typical tw values range from 1 to several seconds, whereas typical T1 values for formation water range from a few milliseconds to a few seconds. However, in a porous medium saturated with two fluid phases, the wetting phase (i.e., water) saturates smaller pores, and the maximum T1 of the aqueous-phase liquid usually reduces to values less than several hundreds of milliseconds.3 Thus, Pl is unity for aqueous-phase liquids in a two-phase system, when data are acquired with typical wait-time parameters in an MRIL®* DTW acquisition (i.e., tw, S,˜1–2 seconds and tw, L,˜6–10 seconds).

FEATURES OF MECHANISM OF GAS-LIQUID POLYAMIDATION IN FOAMY HYDRODYNAMIC MODE

2020 ◽  
Vol 63 (3) ◽  
pp. 67-74
Author(s):  
Vladimir A. Nikiforov ◽  
Elena I. Laguseva ◽  
Evgeny A. Pankratov ◽  
Ilya S. Zhokhov
Keyword(s):  
Liquid Phase ◽  
Dicarboxylic Acid ◽  
Gas Phase ◽  
Reaction System ◽  
Reaction Chamber ◽  
Phase System ◽  
Aromatic Diamines ◽  
Two Phase ◽  
Reactor Unit ◽  
Hydrodynamic Mode

The brief characteristics of the reaction system of pilot production of fatty-aromatic polyamides based on aliphatic diamines (acylated monomers) and dicarboxylic acid dichloroanhydrides (acylating monomers) by the method of gas-liquid polycondensation in a highly turbulized foamy hydrodynamic mode are described. Technological scheme and rational instrumentation of the technology of polyterephthalamides, the reactor unit (reactor-fibridator), which includes a two-stage reaction chamber and a gas phase generating chamber coaxially located under it, chemistry and operating principle of the facility are shown. The method combines the chemical processes of polyamidation with the physical processes of the reaction molding of polyamide fibrids or gas-structural elements used in the technology of gas-filled plastics. The reaction system of the method includes three structural units: a liquid phase (aqueous alkaline solution of aliphatic, cycloaliphatic and fatty-aromatic diamines), a gas phase (superheated vapours of aromatic and aliphatic dicarboxylic acid dichloroanhydrides, dispersed in a dynamic airflow or inert gas) and an interface (gas-liquid interface). Gas-liquid polyamidation is accompanied by phase formation: the reaction system during the process becomes three-phase system – the swollen polymer forms a solid mobile phase (target product), which acts as a foamy mode stabilizer, which allows technological process to proceed at optimal linear gas phase rates of 30–35 m/s (unlike classical two-phase foamy mode – 4 m/s). A polyamidation mechanism at the liquid-gas interface is proposed, which includes two versions of the process (adsorption and condensation) depending on the ratio of the temperature characteristics of the acylated monomer and the liquid phase carrying the acylating monomer. Analysis of the proposed versions of the mechanism allows you to make an engineering decision on the expediency of organizing a cycle in the liquid phase. Possible criteria for predicting the versions of the mechanism and examples of reaction systems with condensation and absorption versions of polyamidation are given.

Axial gas phase dispersion in a molten salt oxidation reactor

2004 ◽  
Vol 21 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
Yong-Jun Cho ◽  
Hee-Chul Yang ◽  
Hee-Chul Eun ◽  
Jae-Hyung Yoo ◽  
Joon-Hyung Kim
Keyword(s):  
Molten Salt ◽  
Gas Phase ◽  
Phase Dispersion ◽  
Oxidation Reactor

Gas-Agitated Liquid-Liquid Extraction in a Spray Column

1994 ◽  
Vol 59 (10) ◽  
pp. 2235-2243 ◽  
Author(s):  
Milan Sovilj ◽  
Goran Kneževic
Keyword(s):  
Gas Phase ◽  
Liquid Extraction ◽  
Hydrodynamic Characteristics ◽  
Extraction Column ◽  
Phase System ◽  
Two Phase ◽  
Flow Rates ◽  
Liquid Liquid Extraction ◽  
Three Phase ◽  
Phase Water

The hydrodynamic characteristics of the air water toluene three-phase system in a spray extraction column at 20 °C were examined. The average and local hold-up data of the dispersed phase were determined in dependence on the flow rates of the continuous, dispersed and gaseous phases. The average gas phase hold-up was also measured and analyzed. A comparison was made of the hydrodynamic characteristics of the two-phase (water - toluene) and three-phase (air - water - toluene) systems.

Estimation of Gas and Liquid Flow Rates in Gas-Liquid Two-Phase System

2002 ◽  
Author(s):  
Koji Mori ◽  
Tetsumasa Ono ◽  
Masuo Kaji ◽  
Toru Sawai
Keyword(s):  
Gas Phase ◽  
Liquid Flow ◽  
Annular Flow ◽  
Water System ◽  
Phase System ◽  
Two Phase ◽  
Flow Rates ◽  
Mean Values ◽  
Pressure Drops ◽  
Flow Channels

A new method of estimating gas and liquid flow rates is proposed for a gas-liquid two-phase flow system. The method involves measurement of pressure drops in horizontal and vertical flow channels, and calculation of flow rates by Lockhart-Martinelli correlation. The method does not require the insertion of sensing device into the flow channel and does not rely on previously calibrated correlations. Experiments are performed in slug, froth and annular flow regimes for an air-water system, and the usefulness of the proposed method is examined. The results reveal that gas and liquid flow rates can be estimated with the accuracies of 45% for gas phase and 37% for liquid phase with respect to mean values.

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