scholarly journals Effect of Bottom Blowing Mode on Fluid Flow and Mixing Behavior in Converter

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 117
Author(s):  
Jiankun Sun ◽  
Jiangshan Zhang ◽  
Wenhui Lin ◽  
Xiaoming Feng ◽  
Qing Liu
Keyword(s):  
Refractory Lining ◽  
Mixing Time ◽  
Diffusion Path ◽  
Tracer Diffusion ◽  
Mixing Efficiency ◽  
Molten Bath ◽  
Local Flow ◽  
Average Value ◽  
Type Mode ◽  
Bottom Blowing

Bottom blowing agitation plays a crucial role in improving the reaction kinetics condition of molten bath during the steelmaking process. Herein, the influence of bottom blowing mode on the flow and mixing characteristics of molten bath and the abrasion characteristics of refractory lining in a 6:1 scaled-down model of a 100 t converter were investigated using physical and numerical simulations together. Eight bottom blowing modes were designed (uniform, three-point linear co-direction, three-point linear unco-direction, two-point linear, circumferential linear, A-type, V-type, and triangle alternating). The results indicated that bottom blowing mode has a significant effect on the local flow field at the inner ring of bottom tuyeres, the velocity interval distribution, and the turbulent kinetic energy, which in turn determines the tracer diffusion path and rate as well the mixing time of molten bath. Reasonable non-uniform bottom blowing modes promote the interaction between the various stirring sub-zones of the molten bath. Among them, the three-point linear co-direction mode and A-type mode have the highest mixing efficiency under the conditions of bottom blowing and combined blowing, respectively, which is superior to the uniform mode. In addition, the bottom blowing mode changed the location and degree of abrasion of the refractory lining, and the total abrasion of the non-uniform mode was reduced. The average value and fluctuation degree of integral wall shear stress for the A-type mode were minimal.

Dependence of Diffusion Paths on Thermodynamic Factors in Ternary Systems

2008 ◽  
Vol 277 ◽  
pp. 119-124 ◽  
Author(s):  
Ü. Ugaste ◽  
J. Priimets ◽  
Tony Laas
Keyword(s):  
Approximate Equation ◽  
Ternary Systems ◽  
Diffusion Path ◽  
Tracer Diffusion ◽  
Diffusion Paths ◽  
Slope Function ◽  
Experimental Values ◽  
The Impact ◽  
Tracer Diffusion Coefficients ◽  
Thermodynamic Factors

The impact of thermodynamic factors on deviation from linearity of diffusion path in the ternary system Cu-Fe-Ni is analyzed. For that the slope function of the diffusion path for the diffusion couples 65Ni30Cu5Fe –29.5Ni16.5Cu54Fe, 49.5Ni50.5Fe – 51Ni49Cu and 84Cu16Ni – 50Ni50Fe, annealed at 1000°C for 196h, were calculated by an approximate equation using only thermodynamic data. Results of the calculation were compared with the values of the slope function obtained directly from experimental data. It is shown that despite of the fact that the tracer diffusion coefficients of the components in the system Cu-Fe-Ni are not equal the coincidence between the calculated and experimental values of the slope function is remarkable. This allows us to conclude that at least in this case the deviation of the diffusion path from linearity depends mainly on the thermodynamic properties of the system.

Bottom-Blown Stirring Technology Application in Consteel EAF

2011 ◽  
Vol 361-363 ◽  
pp. 639-643 ◽  
Author(s):  
Kai Dong ◽  
Rong Zhu ◽  
Wen Juan Liu
Keyword(s):  
Molten Steel ◽  
Basic Principle ◽  
Liquid Steel ◽  
Mixing Time ◽  
Technology Application ◽  
Heat Time ◽  
Final Slag ◽  
Stirring Effect ◽  
Lime Consumption ◽  
Bottom Blowing

Bottom blown stirring technology application in EAF was studied in this paper. The basic principle of bottom blowing process was researched, the bottom blown stirring can give strong stirring effect on the molten steel bath, thus bath mixing time was shortened, decarburization and dephosphorization were improved, however over stirring would lead to liquid steel incontact with atmosphere air. Reasonable process was considered on Consteel EAF. results show that: with bottom-blown stirring technology, decarburization and dephosphorization increase significantly; oxygen and lime consumption decrease; content of FeO in final slag reduces; and heat time becomes short.

scholarly journals CFD Modelling of Global Mixing Parameters in a Peirce-Smith Converter with Comparison to Physical Modelling

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Deside K Chibwe ◽  
Guven Akdogan ◽  
Chris Aldrich ◽  
Rauf H Eric
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Mixing Time ◽  
Volumetric Flow Rate ◽  
Numerical Code ◽  
Mixing Efficiency ◽  
Phase System ◽  
Cfd Modelling ◽  
Cold Model ◽  
Peirce Smith Converter

The flow pattern and mixing in an industrial Peirce-Smith converter (PSC) has been experimentally and numerically studied using cold model simulations. The effects of air volumetric flow rate and presence of overlaying slag phase on matte on the flow structure and mixing were investigated. The 2-D and 3-D simulations of the three phase system were carried out using volume of fluid (VOF) and realizable k - ɛ turbulence model to account for the multiphase and turbulence nature of the flow respectively. These models were implemented using commercial Computational Fluid Dynamics (CFD) numerical code FLUENT. The cold model for physical simulations was a 1:5 horizontal cylindrical container made of Perspex with seven tuyeres on one side of the cylinder typifying a Peirce-Smith converter. Compressed air was blown into the cylinder through the tuyeres, simulating air or oxygen enriched air injection into the PSC. The matte and slag phases were simulated with water and kerosene respectively in this study. The influence of varying blowing conditions and simulated slag quantities on the bulk mixing was studied with five different air volumetric flow rates and five levels of simulated slag thickness. Mixing time results were evaluated in terms of total specific mixing power and two mixing time correlations were proposed for estimating mixing times in the model of PSC for low slag and high slag volumes. Both numerical and experimental simulations were in good agreement to predict the variation characteristics of the system in relation to global flow field variables set up in the converter through mathematical calculation of relevant integrated quantities of turbulence, Volume Fraction (VF) and velocity magnitudes. The findings revealed that both air volumetric flow rate and presence of the overlaying slag layer have profound effects on the mixing efficiency of the converter.

scholarly journals Analysis of the mixing efficiency of the components of the iron-phosphate mixture in the dry state

2021 ◽  
Vol 1,2021 (1,2021(126)) ◽  
pp. 23-27
Author(s):  
Selyverstov Vadim ◽  
Dotsenko Yurii
Keyword(s):  
Mixing Time ◽  
Experimental Studies ◽  
Iron Phosphate ◽  
Original Method ◽  
Cold Hardening ◽  
Mixing Efficiency ◽  
Experiment Research ◽  
Metal Component ◽  
Dispersed Particles ◽  
Urgent Task

The results of researches of influence of time of mixing of initial components in a dry condition on degree of assimilation of iron-containing component of forming and core iron-phosphate cold-hardening mixes are presented. The percentage of assimilation of the dispersed iron-containing component after each minute of mixing in laboratory runners with a total mixing time of 15 minutes was determined experimentally. Using the original method of particle separation, under the microscope were separated scale particles that were not assimilated (not distributed on the surface of the sand), and weighed them. The dependences of the degree of assimilation of the metal component of the iron-phosphate mixture on the mixing time at different initial contents are obtained. It is shown that the highest degree of absorption of the iron-containing component of iron-phosphate mixtures is achieved by mixing the components of the mixture for the first four to five minutes. Then this figure begins to decrease as the grains begin to collapse under the action of the rolls of the runners, and the forces of electrostatic interaction between the surfaces of the grains and the dispersion medium are reduced compared to the forces of mutual gravity between the dispersed particles of iron-containing component of the mixture. Based on the analysis of theoretical positions and the results of experimental studies, the assumption is made about the possibility of adjusting the conditions and parameters of solidification of phosphate binder systems, in particular using iron-containing filler of a certain dispersion and mixing the components in the dry state for some time. It is known that for mixing the components and assimilation of the required part of the iron-containing component of the mixture uses a significant amount of energy (depending on the type of unit used). To reduce the energy consumption of this process, the urgent task is to determine the degree of assimilation of the iron-containing component of phosphate cold-hardening mixtures in their manufacture by mixing the components in the dry state. Keywords: iron-phosphate cold-hardening mixture, mixing in the dry state, interaction, adhesion, experiment, research, dependence

scholarly journals Modeling of mixing for stirred bioreactors: 3. Mixing time for aerated simulated broths

2002 ◽  
Vol 56 (12) ◽  
pp. 506-513 ◽  
Author(s):  
Dan Cascaval ◽  
Corneliu Oniscu ◽  
Anca-Irina Galaction ◽  
Fiorina Ungureanu
Keyword(s):  
Flow Rate ◽  
Rotation Speed ◽  
Mixing Time ◽  
Volumetric Flow Rate ◽  
Mixing Efficiency ◽  
Complex Flow ◽  
Average Deviation ◽  
Stirred Bioreactor ◽  
Stirred Bioreactors ◽  
Turbine Impeller

This paper presents the experiments on mixing efficiency for aerated media for a laboratory stirred bioreactor with a double turbine impeller. The effects of stirrer rotation speed, air volumetric flow rate and stirrer position on the shaft on mixing time for aerated water and simulated broths (CMCNa solutions) were analyzed. Compared to non-aerated broths, the results indicated that the variation of mixing time with the considered parameters is very different, due to the complex flow mechanism of the gas-liquid dispersion, a mechanism which is changed by changing the broth properties or fermentation conditions. Using the Statistics Toolbox of MATLAB some correlations between the mixing time and rotation speed, air volumetric flow rate and stirrer position on the shaft were established. The proposed equations agree well with the experiments, the average deviation being ?9.02%.

scholarly journals Mixing Performance Analysis of Orbitally Shaken Bioreactors

2020 ◽  
Vol 10 (16) ◽  
pp. 5597
Author(s):  
Angus Shiue ◽  
Shih-Chieh Chen ◽  
Jyh-Cheng Jeng ◽  
Likuan Zhu ◽  
Graham Leggett
Keyword(s):  
Mixing Time ◽  
Power Input ◽  
Energy Dissipation Rate ◽  
Mixing Efficiency ◽  
Thermal Method ◽  
Turbulent Regime ◽  
Mixing Process ◽  
Dimensionless Numbers ◽  
Filling Volume ◽  
Input Variables

This study investigated the efficacy of a novel correlation of power input, energy dissipation rate and mixing time as a potential route to identify the orbitally shaken bioreactor (OSB) system. The Buckingham’s π-theorem was used to designate and transform dimensionless Newton numbers with five relevant power input variables. These variables were empirically varied to evaluate the correlation among the dimensionless numbers. The Newton number decreases with the increased shaking frequency and filling volume. Previous work has focused on optimizing the mixing process by evaluating different shaking and agitation mixing methods. We establish a new mixing process and assessable measurement of the mixing time in the OSB. An innovative explanation of mixing time for the thermal method is proposed. The optimal mixing time is independent of the temperature of filled liquid. The dimensionless mixing number remained constant in the turbulent regime and increasing with the increased liquid viscosity and filling volume. Our findings revealed that the observed correlation is a practical tool to figure the power consumption and mixing efficiency as cell cultivation in all OSB scales and is fully validated when scaling–up system.

scholarly journals Comparative analysis of mixing efficiency and distribution induced by radial impellers in bioreactors with stirred bed of immobilized cells

2010 ◽  
Vol 16 (1) ◽  
pp. 47-64
Author(s):  
Anca-Irina Galaction ◽  
Anca-Marcela Lupăşteanu ◽  
Marius Turnea ◽  
Dan Caşcaval
Keyword(s):  
Experimental Data ◽  
Comparative Analysis ◽  
Immobilized Cells ◽  
Mixing Time ◽  
Mixing Efficiency ◽  
Rushton Turbine ◽  
Mobile Bed ◽  
Main Factors ◽  
Good Concordance

The influences of the main factors on the mixing efficiency and distribution for a bioreactor with stirred/mobile bed of immobilized S. cerevisiae cells in alginate (biocatalyst particles with 4, 4.6 and 5.2 mm diameters) have been comparatively analyzed for six radial impellers: a disperser sawtooth, Smith turbine, a pumper mixer, a curved bladed turbine, a paddle with six blades, a pitched bladed turbine vs. Rushton turbine. The most efficient impellers, from the viewpoint of intensity and uniformity of the suspension circulation were found to be the Smith turbine, the paddle with six blades and the pitched bladed turbine. The mathematical correlations describing the influence of the main factors on mixing time were established for each studied impeller offering a good concordance with the experimental data (the average deviations vary from ?7.9% for pitched bladed turbine to ?12.1% for disperser sawtooth).

Effects of Bath Depth and Eccentricity on Mixing Phenomena in Shaking Ladle

2014 ◽  
Vol 0 (0) ◽  
Author(s):  
Shanqiang Ni ◽  
Haijuan Wang ◽  
Jun Zhang ◽  
Shaojun Chu
Keyword(s):  
Electrical Conductivity ◽  
Deep Water ◽  
Mixing Time ◽  
Mixing Efficiency ◽  
Water Type ◽  
Medium Carbon ◽  
Bath Depth ◽  
Flow Phenomena ◽  
Industry Practice ◽  
Metallurgical Processes

AbstractWater modeling experiments were carried out to investigate the mixing time and fluid flow phenomena in a shaking ladle, which is widely used in production of low and medium carbon ferromanganese and ferrochrome and also other metallurgical processes. Mixing time was determined by electrical conductivity probe method. A new concept of CSS-MT (critical shaking speed based on mixing time) was defined, which was different from the previous CSS-WH (critical shaking speed based on wave height). And the influences of bath depth and eccentricity on the CSS-MT were studied. The results showed that the mixing behaviors in shaking ladle can be categorized into shallow water type and deep water type, and the mixing efficiency of the former is poor and should be avoided in the industry practice. For the deep water type, the CSS-MT increases with increasing of bath depth and is approximately 15 rpm greater than the CSS-WH obtained from Ishii’s empirical formula. A larger eccentricity is helpful to decrease the critical shaking speed within certain limitations which is 30 mm; however, it is useless for increasing the eccentricity when it is above the limitation.

CO2 LASER ABLATION MICROCHANNEL BASED ON KOCH FRACTAL PRINCIPLE

2019 ◽  
Vol 27 (05) ◽  
pp. 1950141
Author(s):  
XUEYE CHEN ◽  
YUE TIAN ◽  
SHUAI ZHANG
Keyword(s):  
Mixing Time ◽  
Laser System ◽  
Scanning Speed ◽  
Mixing Efficiency ◽  
Thermal Bonding ◽  
Manufacturing Method ◽  
Laser Systems ◽  
Koch Fractal ◽  
Koch Fractal Principle ◽  
The Impact

In this paper, we focussed on the processing power of CO2 laser systems and the impact of scanning speed, scanning power and number of scans on the quality of microchannels. We created microchannels which are based on the Koch fractal principle through a flexible and low-cost CO2 laser system. The processing and manufacturing method of Koch fractal micromixer on polymethyl methacrylate (PMMA) substrate was also studied. The microchannel structure based on the Koch fractal principle can increase the contact area and mixing time of the fluid and improve the mixing efficiency of the micromixer. In the experiment, our speed is 2, 4 and 6[Formula: see text]mm/s, the number of scans is 2/3/4 times and the power is 4, 8 and 12[Formula: see text]W. As the power and number of scans increase and the speed decreases, the width and depth of the microchannel are changed more clearly, which contributes to the successful thermal bonding of the Koch fractal micromixer and avoids thermal bonding due to overvoltage. By comparing the experimental data, we found that the width and depth of the channel are ideal when the speed is 2[Formula: see text]mm/s, the number of scans is 4 and the power is 12[Formula: see text]W. Because of the lower cost of PMMA, the use of CO2 laser systems to fabricate microchannels on PMMA substrates will have broad application value, reduce cost and be easier to manufacture.

scholarly journals CFD simulation of the hydrodynamics and mixing time in a stirred tank

2010 ◽  
Vol 16 (4) ◽  
pp. 379-386 ◽  
Author(s):  
Aoyi Ochieng ◽  
Maurice Onyango
Keyword(s):  
Cfd Simulation ◽  
Draft Tube ◽  
Mixing Time ◽  
Operating Cost ◽  
Flow Fields ◽  
Stirred Tank ◽  
Mixing Efficiency ◽  
Phase System ◽  
Rushton Turbine ◽  
Power Draw

Hydrodynamics and mixing efficiency in stirred tanks influence power draw and are therefore important for the design of many industrial processes. In the present study, both experimental and simulation methods were employed to determine the flow fields in different mixing tank configurations in single phase system. The laser Doppler velocimetry (LDV) and computational fluid dynamics (CFD) techniques were used to determine the flow fields in systems with and without a draft tube. There was a reasonable agreement between the simulation and experimental results. It was shown that the use of a draft tube with the Rushton turbine and hydrofoil impeller resulted in a reduction in the homogenization energy by 19.2% and 17.7%, respectively. This indicates that a reduction in the operating cost can be achieved with the use of a draft tube in a stirred tank and there would be a greater cost reduction in a system stirred by the Rushton turbine compared to that stirred by a propeller.

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