Experimentally Validated CFD Model for Gas-Liquid Flow in a Round-Bottom Stirred Tank Equipped with Rushton Turbine

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
Dmitry Vladimirovich Gradov ◽  
Arto Laari ◽  
Ilkka Turunen ◽  
Tuomas Koiranen
Keyword(s):  
Liquid Flow ◽  
Gas Flow ◽  
Turbulence Models ◽  
Power Input ◽  
Stirred Tank ◽  
Cfd Model ◽  
Dissipation Energy ◽  
Measured Velocity ◽  
Rushton Turbine ◽  
Gas Liquid Flow

Abstract Hydrodynamics of gas-liquid flow in a round-bottom stirred tank is modelled at two gas flow rates, constant bubble size and agitator speed of 300 rpm. A round-bottom tank equipped with four baffles and a Rushton turbine was chosen to represent a typical reactor used in hydrometallurgical processes operating under pressure. The applicability of different momentum interchange models and the Realizable k-ε, SST k-ω, and RSM turbulence models was studied using CFD software. The results were compared and validated against experimental data from Particle Image Velocimetry measurements by means of liquid and gas velocity distributions. In addition, energy balance between power input and dissipation energy was compared for the different turbulence models. The CFD model was found to be in good agreement with the measurements. Of the turbulence models studied, the Realizable k-ε model showed best agreement with the measured velocity profiles. Popular drag force models proposed in the literature were assessed, as was the influence of inclusion of non-drag forces. Gas flow was found to affect the liquid phase flow in the tank by generating an additional secondary circulation loop in the upper part of the reactor.

scholarly journals Investigations of mass transfer in annular gas-liquid flow in a microreactor

2016 ◽  
Vol 37 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Paweł Sobieszuk ◽  
Karolina Napieralska
Keyword(s):  
Mass Transfer ◽  
Cross Section ◽  
Chemical Reaction ◽  
Liquid Flow ◽  
Annular Flow ◽  
Gas Flow ◽  
Absorption Rate ◽  
Transfer Coefficients ◽  
Water Solutions ◽  
Gas Liquid Flow

Abstract The paper presents an investigation of mass transfer in gas-liquid annular flow in a microreactor. The microreactor had a meandered shape with a square cross-section of the channel (292×292 μm, hydraulic diameter 292 μm) and 250 mm in length. The rate of CO2 absorption from the CO2/N2 mixture in NaOH (0.1 M, 0.2 M, 0.7 M, 1.0 M and 1.5 M) water solutions was measured. Two velocities of gas flow and two velocities of liquid flow were used. In two cases a fully developed annular flow at the beginning of the channel was observed, whilst in two cases annular flow was formed only in about 2/3 of the microchannel length. Based on the measurements of CO2 absorption rate, the values of volumetric liquid - side mass transfer coefficients with the chemical reaction were determined. Then physical values of coefficients were found. Obtained results were discussed and their values were compared with the values predicted by literature correlations.

scholarly journals STUDY OF THE INFLUENCE OF CONSTRUCTION AND MODE PARAMETERS ON THE HYDRODYNAMICS OF A HOLLOW VORTEX APPARATUS

2021 ◽  
pp. 47-50
Keyword(s):  
Pressure Drop ◽  
Hydraulic Resistance ◽  
Liquid Flow ◽  
Gas Flow ◽  
Efficient Design ◽  
Contact Heat ◽  
Dust Collection ◽  
Hollow Vortex ◽  
Gas Liquid Flow ◽  
Vortex Apparatus

The research was to determine the more efficient design of the swirler from the point of view of hydrodynamics and heat and its optimal parameters. Various swirl designs were manufactured and tested. After preliminary studies conducted on a laboratory installation with a glass working apparatus, several swirlers were selected taking into account their hydraulic resistance, the structure of the swirling gas-liquid flow, and the amount of liquid entrainment by gas. The results of an experimental study of the hydrodynamics of a hollow vortex apparatus with one and two tangential and axial swirlers. Hydraulic losses in the channel and in the swirls during the direct downward movement of gas and gas-liquid flow are determined. In addition, studies of the hydraulic resistance of a vortex-type device allow us to determine the energy consumption of this device for conducting complex processes of dust collection and absorption or contact heat exchange. The hydraulic resistance in the presence of a liquid film is higher than in the case of a single-phase gas flow. The pressure drop in the studied vortex apparatus does not exceed the resistance of high-performance cyclones and vortex-type devices of other designs. The effect of the twist coefficient of gas swirlers, gas velocity, and liquid flow on the pressure drop in the vortex apparatus is established

scholarly journals Analysis of Gas-Liquid Flow in an Aerated Reactor Equipped with a Coaxial Mixer through Tomography and CFD

2021 ◽  
Author(s):  
Nasim Hashemi
Keyword(s):  
Power Consumption ◽  
Liquid Flow ◽  
Critical Speed ◽  
Gas Flow ◽  
Mixing Time ◽  
Gas Holdup ◽  
Bubble Size Distribution ◽  
Speed Ratio ◽  
Pitched Blade Turbine ◽  
Gas Liquid Flow

This doctoral thesis addresses the mixing of highly viscous Newtonian fluids (corn syrup solutions) in a novel aerated reactor equipped with a central impeller (a pitched blade turbine in upward or downward pumping mode) and a wall scraping anchor. The non-intrusive electrical resistance tomography (ERT), dynamic gas disengagement method (DGD), design of experiments (DOE), computational fluid dynamics (CFD), and population balance model (PBM) were employed to characterize the performance of this novel aerated system. The performance criteria to be examined were mixing time, power uptake, gas holdup, and bubble size distribution. In this study, novel correlations were developed to estimate the gassed power drawn by the coaxial mixer, mixing time, and gas holdup. In addition, to obtain a master power curve, two new dimensionless correlations were proposed for the generalized power number and gas flow number by incorporating the equivalent rotational speed for the coaxial mixer, speed ratio (central impeller speed/anchor speed), and the central impeller power fraction into these two correlations. The experimental data demonstrated that gas flow affected the aerated anchor power consumption and central impeller power consumption in different manners. It was also found that at the higher fluid viscosity and beyond the critical speed ratio of 10, the anchor power consumption was increased by increasing the speed ratio (i.e. decreasing the anchor speed). It was shown that in the presence of gas, the anchor impeller in combination with the upward pumping pitched blade turbine in the co-rotating mode exhibited shorter mixing times and lower power consumption than the anchor-downward pumping pitched blade coaxial mixer. To enhance the efficiency of the aerated mixer, it is critical to investigate the influence of the gas-liquid flow within the vessel on the bubble size distribution (BSD) and the local and global gas holdup. To achieve this goal, the effects of the bubble breakup and coalescence on the BSD within the vessel were incorporated into the CFD model through the CFD-PBM coupling. The experimental and simulation results showed that beyond the critical speed ratio of 10, the volume fractions of the large bubbles decreased while the volume fractions of the small bubbles increased.

Absorption and Mass Transfer of CO2 in Monoethanolamine Solution

2016 ◽  
Vol 859 ◽  
pp. 153-157
Author(s):  
Pao Chi Chen ◽  
Sheng Zhong Lin
Keyword(s):  
Mass Transfer ◽  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Bubble Column ◽  
Operating Conditions ◽  
Gas Flow Rate ◽  
Constant Ph ◽  
Gas Liquid Flow

This work uses a continuous bubble-column scrubber for the absorption of CO2 with a 5M MEA solution under a constant pH environment to explore the effect of the pH of the solution and gas-flow rate (Qg) on the removal efficiency (E), absorption rate (RA), overall mass-transfer coefficient (KGa), liquid flow rate (QL), gas-liquid flow ratio (γ), and scrubbing factors (φ). From the outlet CO2 concentration with a two-film model, E, RA, KGa, QL, γ, and φ can be simultaneously determined at the steady state. Depending on the operating conditions, the results show that E (80-97%), RA(2.91x10-4-10.0x10-4mol/s-L), KGa (0.09-0.48 1/s), QL(8.74-230.8mL/min), γ (0.19-5.39), and φ (0.031-0.74 mol/mol-L) are found to be comparable with other solvents. In addition, RA, KGa, E, and QL have been used to correlate with pH and Qg, respectively, with the results further explained.

Numerical Simulation of Gas-Liquid Flow in a Stirred Tank with Swirl Modification

2009 ◽  
Vol 32 (8) ◽  
pp. 1266-1273 ◽  
Author(s):  
Y.-H. Zhang ◽  
Y.-M. Yong ◽  
Z.-S. Mao ◽  
C. Yang ◽  
H.-Y. Sun ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Liquid Flow ◽  
Stirred Tank ◽  
Gas Liquid Flow

scholarly journals Homogeneous and re-circulatory gas–liquid flow in a bubble column: A numerical investigation using OpenFOAM

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Saroj K. Panda
Keyword(s):  
Liquid Flow ◽  
Bubble Size ◽  
Bubble Column ◽  
Cfd Model ◽  
Gas Velocity ◽  
Drag Forces ◽  
Circulatory Flow ◽  
Gas Liquid Flow ◽  
Lift And Drag ◽  
Superficial Gas Velocity

AbstractThis work presents the influence of the sparger opening area, gas velocity, and bubble size on hydrodynamics and transition of the flow regime from uniform to re-circulatory in a rectangular bubble column using OpenFOAM. In the course of development of the model, the effect of several drag closures and lift on the predictability of the CFD model was studied by comparing the predictions with published experimental results. Reynolds number-based drag closure was found to be suitable for uniform sparger whereas Tsuchiya drag (Tsuchiya et al. in Chem Eng Sci 52:3053–3066, 1997. https://doi.org/10.1016/S0009-2509(97)00127-9) was used to simulate gas–liquid flow for other spargers. Simulations were performed for seven different spargers with opening area 18–100% (superficial gas velocity of 2.9–5.8 cm/s) and bubble size of 2–8 mm. The smaller opening area and higher gas velocity promote the re-circulatory flow in the bubble column. Change in bubble size affects the hydrodynamics due to change in lift and drag forces.

Gas-Liquid Flow Through Horizontal Eccentric Annuli: CFD and Experiments Compared

2011 ◽  
Author(s):  
Mehmet Sorgun ◽  
Reza E. Osgouei ◽  
M. Evren Ozbayoglu ◽  
A. Murat Ozbayoglu
Keyword(s):  
Liquid Flow ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Flow Patterns ◽  
Phase Flow ◽  
Cfd Model ◽  
Flow Loop ◽  
Two Phase ◽  
Gas Liquid Flow

Although flow of two-phase fluids is studied in detailed for pipes, there exists a lack of information about aerated fluid flow behavior inside a wellbore. This study aims to simulate gas-liquid flow inside horizontal eccentric annulus using an Eulerian-Eulerian computational fluid dynamics (CFD) model for two-phase flow patterns i.e., dispersed bubble, dispersed annular, plug, slug, churn, wavy annular. To perform experiments using air-water mixtures for various in-situ air and water flow rates, a flow loop was constructed. A digital high speed camera is used for recording each test dynamically for identification of the liquid holdup and flow patterns. Results showed that CFD model predicts frictional pressure losses with an error less than 20% for all two-phase flow patterns when compared with experimental data.

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