scholarly journals Modelling of Fluid Flow and Residence Time Distribution in a Five-strand Tundish

2020 ◽  
Author(s):  
Dong-Yuan Sheng ◽  
Qiang Yue
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Volume Fraction ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Passive Scalar ◽  
Control Device ◽  
Dead Volume ◽  
Cfd Modelling

The quantified residence time distribution (RTD) provides a numerical characterization of mixing in the continue casting tundish, thus allowing the engineer to better understand the metallurgical performance of the reactor. This paper describes a computational fluid dynamic (CFD) modelling study for analyzing the flow pattern and the residence time distribution in a five-strand tundish. Two passive scalar transport equations are applied to separately calculate the E-curve and F-curve in the tundish. The numerical modelling results are compared to the water modelling results for the validation of the mathematical model. The volume fraction of different flow regions (plug, mixed and dead) and the intermixing time during the ladle changeover are calculated to study the effects of the flow control device (FCD) on the tundish performance. The result shows that a combination of the U-baffle with deflector holes and the turbulence inhibitor has three major effects on the flow characteristics in the tundish: i) reduce the extent of the dead volume; ii) evenly distribute the liquid streams to each strand and iii) shorten the intermixing time during the ladle changeover operation.

scholarly journals Modeling of Fluid Flow and Residence-Time Distribution in a Five-Strand Tundish

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1084 ◽  
Author(s):  
Dong-Yuan Sheng ◽  
Qiang Yue
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Volume Fraction ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Passive Scalar ◽  
Control Device ◽  
Dead Volume ◽  
Cfd Modeling

Quantified residence-time distribution (RTD) provides a numerical characterization of mixing in the continuous casting tundish-thus allowing the engineer to better understand the metallurgical performance of the reactor. This study describes a computational fluid dynamic (CFD) modeling study for analyzing the flow pattern and the residence-time distribution in a five-strand tundish. Two passive scalar-transport equations were applied to separately calculate the E-curve and F-curve in the tundish. The numeric modeling result were compared to water-modeling results to validate the mathematical model. The volume fraction of different flow regions (plug, mixed and dead) and the intermixing time during the ladle changeover were calculated to study the effects of the flow control device (FCD) on the tundish performance. From the results of CFD calculations, it can be stated that a combination of the U-baffle with deflector holes and the turbulence inhibitor had three major effects on the flow characteristics in the tundish: (i) to reduce the extent of the dead volume; (ii) to evenly distribute the liquid streams to each strand and (iii) to shorten the intermixing time during the ladle changeover operation.

scholarly journals Design Optimization of a Single-Strand Tundish Based on CFD-Taguchi-Grey Relational Analysis Combined Method

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1539
Author(s):  
Dong-Yuan Sheng
Keyword(s):  
Residence Time ◽  
Grey Relational Analysis ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Volume Fraction ◽  
Single Strand ◽  
Dead Volume ◽  
Analysis Method ◽  
Relational Analysis ◽  
Grey Relational

A novel digital design methodology that combines computational fluid dynamics (CFD) modelling and Taguchi-Grey relational analysis method was presented for a single-strand tundish. The present study aimed at optimizing the flow control device in the tundish with an emphasis on maximizing the inclusion removal rate and minimizing the dead volume fraction. A CFD model was employed to calculate the fluid flow and the residence-time distribution of liquid steel in the tundish. The Lagrangian approach was applied to investigate the behavior of non-metallic inclusions in the system. The calculated residence-time distribution curves were used to analyze the dead volume fraction in the tundish. A Taguchi orthogonal array L9(3^4) was used to analyze the effects of design factors on both single and multiple responses. Moreover, for the purpose of meeting the multi-objective target functions, grey relational analysis and analysis of variance were used. The optimum positions of the weir and the dam were obtained based on the design targets. A special focus of this study was to demonstrate the capabilities of the Taguchi-Grey relational analysis method as a powerful means of increasing the effectiveness of CFD simulation.

scholarly journals Modeling Residence Time Distribution (RTD) Behavior in a Packed-Bed Electrochemical Reactor (PBER)

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Sananth H. Menon ◽  
G. Madhu ◽  
Jojo Mathew
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Flow Model ◽  
Plug Flow ◽  
Flow Characteristics ◽  
Theoretical Models ◽  
Packed Bed ◽  
Electrochemical Reactor ◽  
Tracer Studies

This paper focuses on understanding the electrolyte flow characteristics in a typical packed-bed electrochemical reactor using Residence Time Distribution (RTD) studies. RTD behavior was critically analyzed using tracer studies at various flow rates, initially under nonelectrolyzing conditions. Validation of these results using available theoretical models was carried out. Significant disparity in RTD curves under electrolyzing conditions was examined and details are recorded. Finally, a suitable mathematical model (Modified Dispersed Plug Flow Model (MDPFM)) was developed for validating these results under electrolyzing conditions.

CFD Analysis of Gas Flow Characteristics and Residence Time Distribution in a Rotating Spherical Packing Bed

2019 ◽  
Vol 58 (47) ◽  
pp. 21717-21729
Author(s):  
Wen-Ling Li ◽  
Xue-Ying Gao ◽  
Yi Ouyang ◽  
Jia-Qi Wang ◽  
Guang-Wen Chu ◽  
...  
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Cfd Analysis ◽  
Spherical Packing

scholarly journals Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds

2012 ◽  
Vol 326-328 ◽  
pp. 279-284
Author(s):  
António Albuquerque
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Loading Rate ◽  
Solid Material ◽  
Dead Volume ◽  
Nitrogen Compounds ◽  
In Series ◽  
Reactive Tracer ◽  
Tracer Experiments

The evaluation of the dispersion in vegetated beds may allow indentifying mechanisms that affect the transport and reaction of solutes, namely organic and nitrogen compounds. A set of non-reactive tracer experiments (slag injection) was performed in a vegetated bed (a mesocosm with a LECA-based substratum and colonized withPhragmites australis) used for the removal of organic and nitrogen pollutant loads. Loads of approximately 300 mg COD/L and 30 mg NH4-N/L and a hydraulic loading rate of 3.5 cm/d were used. The results showed a delay in all the residence time distribution (RTD) curves and a variation in the dimensionless residence time (μ(m,θ)) of the E(θ) curves, which means that the mass centre of the impulse was late relatively to the expected one. A strong dispersion and tracer retention (due to the presence of stagnated areas and internal recirculation) was observed, especially in the first 33 cm of the bed, which seems to have been related to the presence of complex clusters of roots, solid material, biofilm and LECA particles. An analytical solution of the Multiple-Tanks-in-Series (MTS) model well represents the RTD curves obtained in the tracer experiments. The detected dispersion and dead volume ratios (7% to 12%) did not affect the performance of the bed, which presented mean removal efficiencies of 85% and 60.4% for COD and NH4-N, respectively.

Experimental Study on Residence Time Distribution of New Type Multi-Tubular Stirred Reactor

2011 ◽  
Vol 391-392 ◽  
pp. 629-632
Author(s):  
Qiu Yue Zhao ◽  
Ting An Zhang ◽  
Yan Liu ◽  
Guo Zhi Lv ◽  
Shu Chan Wang
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Flow Characteristics ◽  
Mass Transfer Process ◽  
Stirred Reactor ◽  
Time Flow ◽  
New Type ◽  
Flow Flux ◽  
The Relationship

Multi-tubular stirred reactor is an efficient pressure reactor. It is designed and developed to strengthen the mixing and mass transfer process. In order to research the flow characteristics in this reactor, the residence time distribution is measured at different rotation speeds from 50rpm to 350rpm and different flow rates from 1.8m3/h to 3.9m3/h. The relationship among mean residence time, flow flux and rotate speed is obtained.

scholarly journals Spatial and Temporal Validation of a CFD Model Using Residence Time Distribution Test in a Tubular Reactor

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 94
Author(s):  
José Rivas ◽  
M. Constanza Sadino-Riquelme ◽  
Ignacio Garcés ◽  
Andrea Carvajal ◽  
Andrés Donoso-Bravo
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Fluid Dynamic ◽  
Tubular Reactor ◽  
Temporal Distribution ◽  
Cfd Model ◽  
Ansys Fluent ◽  
Cfd Models ◽  
Temporal Validation

Computational fluid dynamic (CFD) has been increasingly exploited for the design and optimization of (bio)chemical processes. Validation is a crucial part of any modeling application. In CFD, when validation is done, complex and expensive techniques are normally employed. The aim of this study was to test the capability of the CFD model to represent a residence time distribution (RTD) test in a temporal and spatial fashion inside a reactor. The RTD tests were carried out in a tubular reactor operated in continuous mode, with and without the presence of artificial biomass. Two hydraulic retention times of 7.2 and 13 h and superficial velocities 0.65, 0.6, 1.3, and 1.1 m h−1 were evaluated. As a tracer, an aqueous solution of methylene blue was used. The CFD model was implemented in ANSYS Fluent, and to solve the equations system, the SIMPLE scheme and second-order discretization methods were selected. The proposed CFD model that represents the reactor was able to predict the spatial and temporal distribution of the tracer injected in the reactor. The main disagreements between the simulations and the experimental results were observed, especially in the first 50 min of the RTD, caused by the different error sources, associated to the manual execution of the triplicates, as well as some channeling or tracer by-pass that cannot be predicted by the CFD model. The CFD model performed better as the time of the experiment elapsed for all the sampling ports. A validation methodology based on an RTD by sampling at different reactor positions can be employed as a simple way to validate CFD models.

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