Statistical pressure characteristics in modelling of gas-liquid reactors

1979 ◽  
Vol 44 (1) ◽  
pp. 56-68 ◽  
Author(s):  
Jan Čermák ◽  
František Kaštánek ◽  
Antonín Havlíček
Keyword(s):  
Gas Flow ◽  
Pressure Fluctuations ◽  
Liquid System ◽  
Considerable Effect ◽  
Tube Formation ◽  
Venturi Tube ◽  
Sieve Plate ◽  
Average Porosity ◽  
Integral Characteristics ◽  
The Given

The integral characteristics (average porosity and product kLa) and the fluctuating component of static pressure inside the gas-liquid system were measured in two types of column reactors with different gas distributors. It has been determined that at the same gas velocity in the reactor with a Venturi tube as the gas distributor the mean porosities are about 1.5 times greater than with the sieve plate reactor. To this corresponds, especially, at small gas flow rates even higher ratio of coefficients kLa. Standard deviation of pressure fluctuations becomes with the Venturi tube reactor for orders of magnitude greater then with the sieve plate reactor. The analysis of pressure fluctuations has demonstrated that in the reactor with the Venturi tube the decisive portion of fluctuation output corresponds to frequencies within the band 10-30 Hz, while in the reactor with the given type of the sieve plate to the band 0-10 Hz. In the reactor with the Venturi tube formation of surface waving has no considerable effect on flow of the gas phase, though the amplitudes in both types of reactors are comparable.

The Venturi Tube as a Liquefied-Gas Flow Measuring Device

1960 ◽  
pp. 282-288 ◽  
Author(s):  
J. R. Purcell ◽  
A. F. Schmidt ◽  
R. B. Jacobs
Keyword(s):  
Gas Flow ◽  
Venturi Tube ◽  
Measuring Device ◽  
Liquefied Gas

Wet Gas Flow Measurement Base on a Symmetrical Venturi Tube

2012 ◽  
Vol 12 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Lide Fang ◽  
Lili Pang ◽  
Xiaoting Li ◽  
Xiuming Xiang ◽  
Qinghua Lu
Keyword(s):  
Flow Measurement ◽  
Gas Flow ◽  
Venturi Tube ◽  
Wet Gas ◽  
Measurement Base

scholarly journals Hydrodynamics of pulsed sieve-plate extraction columns

2020 ◽  
Vol 74 (1) ◽  
pp. 1-14
Author(s):  
Milan Sovilj ◽  
Momcilo Spasojevic
Keyword(s):  
Continuous Phase ◽  
Liquid System ◽  
Axial Dispersion ◽  
Superficial Velocity ◽  
Dispersed Phase ◽  
Geometrical Parameters ◽  
Drop Diameter ◽  
Sieve Plate ◽  
Axial Dispersion Coefficient ◽  
Hydrodynamic Parameters

This paper presents a review of some hydrodynamic parameters in pulsed sieve-plate extraction columns. The hydrodynamic parameters in liquid-liquid systems in these columns were analyzed regarding the effects of operating and geometrical parameters. The values of Sauter mean drop diameter were function of the existing work flow regimes in the column device defined as mixer-settler, emulsion and dispersion regimes. It was concluded that the dispersed-phase holdup was a function of the mean drop diameter and dispersed-phase superficial velocity. An increase in the dispersed-phase holdup induced an increase in the interface area in the liquid-liquid system. Knowledge of the value of the dispersed-phase holdup can be used for calculation of the volumetric mass transfer coefficient, one of the important factor in the design of the column extractor. It was concluded that the increase in the dispersed-phase superficial velocity is causing a decrease in axial dispersion. On the other hand, an increase in the continuous-phase superficial velocity is causing the increase in the axial dispersion coefficient. Some of the empirical equations proposed in literature for calculations of the hydrodynamic parameters were presented. These correlations, derived for determination of the hydrodynamic parameters in pulsed sieve-plate extraction columns, can be used for the design of these liquid-liquid extraction columns.

scholarly journals Modeling of acoustic fields during gas flow around bodies

2020 ◽  
Vol 22 (3) ◽  
pp. 333-351
Author(s):  
Arif R. Bagapov ◽  
Ruslan V. Zhalnin
Keyword(s):  
Acoustic Field ◽  
Gas Flow ◽  
Sound Pressure ◽  
Pressure Fluctuations ◽  
Observation Point ◽  
Pressure Level ◽  
Weno Scheme ◽  
Gas Flows ◽  
Mass Energy ◽  
Energy And Momentum

The article describes the modeling of the acoustic field based on the analysis of pressure fluctuations. For this a model based on the laws of mass, energy and momentum is implemented in a two-dimensional setting. For the calculations, the HLLC scheme for solving the Rieman problem and the WENO scheme for reconstructing the gas-dynamic parameters on the faces between the cells are used. To simulate the acoustic field, a time-averaged characteristic was chosen - the overall sound pressure level (OASPL). The paper considers the acoustic field obtained when a gas flows around a single square body, a cascade of square bodies, a step and a cavity, an interpretation of the ongoing processes is given. The result of the study is the visualization and description of the phenomena that arise when a gas flow around bodies, as well as the study of the effect of removing the observation point on acoustic effects within the simulated area.

Combustor Configuration Influence on Combusion Instabilities Performance

2010 ◽  
Author(s):  
Georgy K. Vedeshkin ◽  
Evgeniy D. Sverdlov ◽  
Alexey N. Doubovitsky
Keyword(s):  
Gas Flow ◽  
Flow Instability ◽  
Combustion Instability ◽  
Low Frequency ◽  
Experimental Investigations ◽  
Flow Recirculation ◽  
Instability Modes ◽  
Conical Diffuser ◽  
Recirculation Zones ◽  
The Given

The paper describes the results of calculations and experimental investigations of combustor configurations. It is shown that combustor configuration effects high frequency and low frequency combustor instabilities, gas dynamics of the flow, recirculation zones dimensions and lean flame out limits. Combustion instability modes had been investigated in two versions of combustor configurations: with the abrupt divergence of the channel and with an inlet conical diffuser. Gas flow instabilities had been investigated in the central recirculation zone without any chemical reactions. As a result the combustion instability model in which a role of a feed back mechanism is performed by hydrodynamic gas flow instability in the combustor is suggested. Modification of the combustor with a conical diffuser with the suggested model of the hydrodynamic combustion instability taken into account made it possible to settle the instability problem for the given combustor.

Experimental Analysis of Venturi-Tube Behavior in Wet Gas Conditions

2020 ◽  
Author(s):  
Olav Mehlum ◽  
Øyvind Hundseid ◽  
Lars E. Bakken
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Volume Fraction ◽  
Volume Flow Rate ◽  
Venturi Tube ◽  
Low Flow ◽  
Detailed Knowledge ◽  
Operation Conditions ◽  
Wet Gas ◽  
Compressor Inlet

Abstract Subsea wet gas compressors have been successfully in operation for approximately 5 years. Their use has proven to increase the recovery by approximately 10% and achieve a reliability up to 98%. Further developed and operation of subsea wet gas compression require detailed knowledge of compressor operability and how shift in operational conditions affect the compressor system. The compressors ability to handle wet gas is documented in detail for a gas volume fraction limited down to 0.90. The 4–5 last year of operation proves the wet gas concepts capability. As years pass by, well pressure and production rate declines which causes the compressor operation point to shift towards the high head and low flow (surge) area of the characteristics. In addition, compressor inlet transients increase due to pipe surge (slugs), requiring a robust control system to prevent instabilities, e.g. compressor surge. It is therefore vital to understand how the compressor inlet flow device behaves at different wet operation conditions. The article documents how a standard dry gas venturi tube behave at different wet gas operation conditions. The venturi is designed according to ISO5167-4 for dry gas conditions and is tested at the low-pressure air water compressor test rig at NTNU. The primary objective of the work has been to visualize the wet flow regime through the transparent venturi tube and to document the wet gas flow rate measurements by means of single-phase meters. The venturi tube is tested in a GMF range from 1 to 0.83 at an air volume flow rate of 1.3m3/s.

Multiphase Flow Induced Vibrations at High Pressure: CFD Analysis of Multiphase Forces

2021 ◽  
Author(s):  
Paul Emmerson ◽  
Mike Lewis ◽  
Neil Barton ◽  
Steinar Orre ◽  
Knud Lunde ◽  
...  
Keyword(s):  
High Pressure ◽  
Multiphase Flow ◽  
Gas Flow ◽  
Production Systems ◽  
Pressure Fluctuations ◽  
High Amplitude ◽  
Operating Pressure ◽  
Cfd Analysis ◽  
Cfd Modelling ◽  
Test Loop

Abstract CFD analysis of a high pressure 2” pipe test loop with water-gas flow was undertaken using three different solvers. Multiphase flow induced forces were predicted on the bends at a range of operating pressures between 10 and 80 barg and compared with forces reconstructed from vibration measurements. Overall the three different CFD solvers predicted consistent results. The fluid forces predicted on the bends of the double U-loop test rig have a good range of values compared to the test reconstructed forces. The forces predicted at low pressure were in line with the experimental reconstructed values, whilst at high pressure all three CFD solvers predicted higher forces. The trend of the forces reducing with increased operating pressure, evident in test, was matched by one of the CFD methods, but less well by the other two. At low operating pressure the forces are dominated by the momentum of the liquid in the multiphase flow, whilst at high pressure the pressure fluctuations and turbulent effects will be more important. All three CFD solvers use VOF methods and above about 40 barg it is possible that they struggle to fully resolve the flow behaviour, which will be more influenced by bubble and droplet entrainment and turbulence. Multiphase flow can induce high amplitude vibrations in piping systems, potentially leading to fatigue failures. CFD modelling offers a potentially powerful tool to provide the flow induced forces required for assessing and diagnosing multiphase flow induced pipework vibration problems in hydrocarbon production systems.

Comparative study of dry pressure drop and flow behaviour of gas flow through sieve plate packing

2020 ◽  
Vol 98 (10) ◽  
pp. 2238-2256
Author(s):  
Min Qiao ◽  
Shaobei Liu ◽  
Weixing Huang ◽  
Renjie Hao ◽  
Taoxian Zhang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Comparative Study ◽  
Gas Flow ◽  
Flow Behaviour ◽  
Sieve Plate ◽  
Flow Through

Nonlinear Bubbling Hydrodynamics in a Gas-Liquid Bubble Column with a Single Nozzle

2003 ◽  
Vol 1 (1) ◽  
Author(s):  
Mingyan Liu
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Chaotic Behavior ◽  
Bubble Column ◽  
Pressure Fluctuations ◽  
Time Signal ◽  
Kolmogorov Entropy ◽  
Gas Flow Rate ◽  
Non Linear ◽  
Liquid Bubble

In this work, the chaotic bubbling mechanism in a gas-liquid bubble column with a single nozzle was investigated. The signal for the analysis was the time series of pressure fluctuations measured from a pressure transducer probe placed in the bubble column close to the nozzle. In order to study the bubbling process, statistical analysis, qualitative and quantitative non-linear analyses were carried out for the pressure fluctuations. Power spectra used as standard statistical measures provided preliminary evidence that bubbling in the middle values of gas flow rates may be chaotic in nature. Phase plots provided a qualitative means of analyzing the fine geometry structure of the attractor reconstructed from the bubbling time signal. Positive finite estimates of the Kolmogorov entropy provided a quantitative evidence of behavior consistent with chaos. Besides previous diagnostic tools, the local non-linear short-term prediction was also used as a supplement method. It was found that the bubbling process exhibits a deterministic chaotic behavior in a certain range of the gas flow rate. When increasing the gas flow rate, the sequence of periodic bubbling, primary and advanced chaotic bubbling, and jetting or random bubbling were successively observed. However, no clear period doubling sequence leading to chaotic behavior was observed. The sharp loss of the ability to predict the pressure signal successfully with the non-linear prediction method provides a strongest evidence of the presence of the chaotic bubbling. The variations of the non-linear invariants, such as the Kolmogorov entropy and the correlation dimension together with the plot of the correlation integral with the operation conditions, might be developed as potential and effective quantitative tools for flow regime identification of the bubbling process.

Dynamic pressure analysis as a tool for determination of sharkskin instability by extrusion of molten polymers

2012 ◽  
Vol 32 (6-7) ◽  
pp. 335-341 ◽  
Author(s):  
Mateusz Barczewski ◽  
Roman Barczewski ◽  
Tomasz Sterzynski
Keyword(s):  
Autocorrelation Function ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Extrusion Process ◽  
Processing Technique ◽  
Considerable Effect ◽  
Visual Observation ◽  
Fast Fourier Transformation ◽  
Signal Acquisition ◽  
Signal Processing Technique

Abstract Increasing requirements which extruded polymeric products should accomplish are imposed to quantitatively characterize the factors which have a considerable effect on extrusion stability. Investigation has been realized by means of a rheological measurement device including a single screw extruder, as well as a rheological die, signal acquisition and analysis system. Due to a specially designed measurement track and modern signal processing technique, the separation of cyclic instabilities from received signals (representing the course of melt pressure) and the definition of the influence on the extrusion process were feasible. This paper demonstrates an example of the application of two new methods which facilitate the detection of sharkskin instability, irrespective of visual observation of the extrudate. Autocorrelation function and frequency analysis based on a fast Fourier transformation (FFT) were used as numeric tools applied to register and control the extrusion process. The flow of molten polymer was studied under various processing conditions, giving an opportunity to split high frequency pressure fluctuations by means of the autocorrelation function and fast Fourier transform, and to create, in the future, a catalogue of data which can be used to define particular distortions in technological investigations.

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