A three-dimensional transient multi-physical field model with comprehensive reduction reaction consideration has been developed to capture the complex processes of a three-phase submerged arc ...furnace. The multi-physics model integrates electromagnetic, fluid flow, reduction reaction, and thermodynamics phenomenon in unison computational framework. The furnace internal structure consists of arc and furnace charge, for which the physical properties include temperature dependence. Aiming to search the optimum design for more efficient industrial operation, the electrode insertion depth is investigated. The predicted temperature distribution of high temperature is in agreement with the measurement and simulation results. The result shows that the temperature of arc zone is maximum, which is 5897.17 K. The high-temperature area of furnace charge is near the arc zone. The temperature distribution is similar with current density. With the increase of electrode insertion depth, the average voltage drop of three arc zones is 11.43, 11.12, 10.83, and 10.35 V, respectively. When the electrode insertion depth is 1.99 and 1.79 m, the maximum magnetic field intensity around the electrode bottom is of 0.068 and 0.063 T. Cr
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mainly reacts under the arc bottom, while iron oxides are reduced less in the same location. An optimum electrode insertion depth exists according to the simulation results.
The objective of this paper is to investigate the energy conservation and resource utilization in the smelting process of ferrochrome pellets. Based on the laws of mass and energy conservation, the ...material and energy flows model has been established in the smelting process of steel belt sintering-submerged arc furnace. To better understand the smelting process from disorder state to order state under energy conservation and resource utilization, the synergy model related to the material and energy has been developed. The state change depends on the fluctuations to the energy critical point. The fluctuations are defined as order parameters, which satisfy all the smelting processes. The value of synergy degree is set as the evaluating indicator to assess the smelting process. The results show that the energy efficiencies of three smelting equipments are 42.89%, 66.17% and 61.44%, respectively. Also, the energy efficiency of the smelting process is 49.15%. The value of synergy degree is 0.584. Several suggestions for the smelting process are proposed based on the synergy model. The synergy degree of the suggestions is 0.632. The present work has a potential to improve the smelting process in efficiency.
•Establish material and energy flows in steel belt sintering-submerged arc furnace.•Define order parameters affecting the synergy relationship on smelting processes.•Set the synergy degree as evaluating indicator for energy and resource saving.•Propose and validate suggestions according to the synergy analysis model.
The steel strip feeding process can effectively improve the macrosegregation, central porosity, shrinkage, cracking, and other defects of continuous casting (CC) round blooms. Based on the ...volume-averaged method, a three-phase mix columnar-equiaxed solidification model is established, which considers the nucleation, growth of the columnar and equiaxed crystals, deposition of equiaxed crystals, and transmission of solutes. The effect of the feeding strip on the temperature, velocity, phase distribution, and macrosegregation distribution in a large vertical CC round bloom was studied. The results show that the CC bloom shell is built by columnar crystals, and equiaxed crystals fabricate the central zone. The feeding of the steel strip enhanced the flow inside the liquid core, which changed the flow direction of the center and end of the liquid core. The liquid phase and the temperature field display a similar distribution, and the liquid core and V-shaped high-temperature zone will gradually shorten with the increasing feeding ratio. A highly consistent distribution of the phase and the macrosegregation was found, and the increase in feeding ratio promotes columnar-to-equiaxed transformation (CET) and improves macrosegregation. Compared with no feeding strip, the extreme values of the macrosegregation index of 1.0% feeding ratio decreased by 37.1%, and the CET point at the sectional radius increased by 17.39%.
Discrete element method (DEM) has been used to investigate the effects of particle contact parameters, sliding friction coefficient (SFC), rolling friction coefficient (RFC) and restitution ...coefficient (RC), in a rotating drum. Their effects were examined in terms of mean power draw, mean collision energy and collision frequency employing response surface method (RSM) in conjunction with analysis of variance (ANOVA) to perform significance analysis for the effects of single factors and factor combinations. Various rotational speed was also considered in the present work. The results revealed that sliding friction coefficient was a determining factor for mean power draw and mean collision energy, and restitution coefficient had the greatest impact on collision frequency. Additionally, sliding friction coefficient and restitution coefficient showed interaction effects on both mean collision energy and collision frequency over the range of rotational speed. Moreover, the sensitivity of particle contact parameters varies with the rotational speed of the drum.
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•Collision behavior of particles in a rotating drum was analyzed using DEM•The sensitivity of particle contact parameters was investigated employing RSM.•Various rotational speed was considered in the present work.
•First developed a coupled model of oxygen and sulfur transfer in ESR process.•Thermochemical and electrochemical reactions were included.•Evolution of oxygen and sulfur concentration was ...demonstrated.•An experiment was carried out to validate the simulation.
A transient three-dimensional (3D) comprehensive mathematical model has been developed to understand oxygen and sulfur transfers in electroslag remelting process. The solutions of the mass, momentum, energy and species conservation equations were simultaneously carried out by finite volume method. The Joule heating and Lorentz force were taken into account. The thermochemical and electrochemical transfers of oxygen and sulfur were represented through the application of a metallurgical thermodynamic and kinetic module. In order to obtain the evolution of oxygen activity, the chemical reaction between dissolved aluminum and dissolved oxygen in the metal was included. The comparison between the measured and simulated data indicates that the model can predicate the transfer behavior with an acceptable accuracy. The thermochemical reaction always removes oxygen and sulfur from the metal, while the electrochemical reaction brings oxygen and sulfur back to the metal through the metal droplet-slag interface, and takes them away from the metal through the metal pool-slag interface. The oxygen removal ratio is about 60%, and the contribution of the electrochemical reaction is around 82%. The sulfur removal ratio is approximately 76%, and the contribution of the electrochemical reaction is around 39%.
A transient three-dimensional model has been proposed to investigate the oxygen transport behavior in electroslag remelting process. The electromagnetism, heat transfer, multiphase flow, and species ...transport were calculated simultaneously by finite volume method. The volume of fluid approach was adopted to trace the metal–slag–air three-phase flow. Based on the necessary thermodynamics of oxygen transport behavior, a kinetic model was established to predict the mass source terms in species transport equation. The kinetic correction factor was proposed to account for the effect of the oxide scale formed on the electrode on the FeO content in slag. Finally, the effect of applied current on the oxygen transfer was studied. The predicted result agrees well with the measured data when the kinetic correction factor is set to be 0.5. The temperature distribution that affects the thermodynamics differs at the interfaces. The oxygen in air is absorbed into slag due to the oxidation at the slag/air interface. The Fe
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in slag and the oxide scale contribute to the increase of FeO content in slag, and the latter one plays the leading role. The oxygen transfer from slag to metal mainly occurs during the formation of the droplet at the slag/metal droplet interface. With the current increasing from 1200 to 1800 A, the oxygen content increases from 76.4 to 89.8 ppm, and then slightly declines to 89.2 ppm when the current increases to 2100 A.
Steel strip feeding into continuous casting mold is an innovative technology improving the slab quality through decreasing the melt superheat and increasing the proportion of equiaxed dendrites. To ...investigate the embedded complex melting and solidification processes, a mathematical model has been developed to model all the essential physical behaviors of the fluid flow, heat transfer, melting, and solidification during steel strip feeding into the mold. The enthalpy method is adopted to describe both the melting of steel strip and the solidification of slab. The complex heat transfer between cold steel strip and hot melt is considered. The melting of moving strip and the growth of solidified shell are compared with the experimental measurements and empirical equation, respectively. The validated model is then used to predict the melting and solidification characteristics during steel strip feeding into the mold. Based on the experimental and numerical findings, the whole melting process of steel strip can be divided into three periods: the steel sheath formation, steel sheath melting, and steel strip melting. Effects of the strip thickness (d0), melt superheat (ΔT), and strip feeding speed (va) on the melting of steel strip have been analyzed. An empirical equation is proposed to correlate the total melting time with aforementioned parameters: lntm=3.748+1.406lnd0−0.32lnva−0.794lnΔT. Furthermore, sensitivity study has also performed to reveal the influence of the strip thickness, melt superheat, and strip feeding speed on the final strip tip position.
In this study, the phase change evolution of the moving strip during steel strip feeding into continuous casting mold is investigated. A pseudo‐steady state is found to predict the strip feeding depth and sensitivity studies are also carried out to assess the influence of the strip thickness, melt superheat, and strip feeding speed on the final strip tip position.
Rapid melting, solidification, and a highly powerful laser all contribute to complex heat transfer and flow phenomena during the directed energy deposition (DED) process. To investigate the impact of ...process parameters on the melt pool and solidification quality during the DED process, a three-dimensional finite element model (FEM) was established. The heat transfer, fluid flow, and solidification during the DED process were investigated. The correct input parameters for GH3536 superalloy were discovered by examining the effects of laser power, scanning speed, and feed rate on the shape of molten pool and interlayer fusion. To forecast the quality of the solidified structure at the cut-off point, temperature gradient and solidification rate discovered in transient thermal distribution were employed. The results shows that the melt pool will grow as a result of high laser power and low scanning speed or feed rate. Concentrating on the expansion of the melt pool is not the best solution because well-solidified microstructure frequently develops in the middle of the parameter set. The correlation between feed rate and laser power is insensitive. At a specific feed rate, the minimum threshold for scanning speed was discovered. When the scanning rate falls below the threshold, uneven solidification structures and anomalous melt pool morphology will take place. The undesirable and potentially fluctuating parameters were indicated, and the laser power and scanning speed range suited for the GH3536 superalloy were summarized. For the feed rate, the center of the parameter set is advised.
The desulfurization behavior in the electromagnetically controlled vibrating-electrode electroslag remelting (ESR) furnace was analyzed, modeled, and numerically simulated. A new transient fully ...coupled mathematical model with the magneto-hydro-dynamic (MHD) multiphase method based on the dynamic mesh-based approach has been developed. Results demonstrate that horizontally vibrating electrode in the slag results in the highest sulfur content contrary to vertically vibrating electrode. The maximum removal ratio of sulfur with horizontally vibrating electrode can reach up to 78 pct, which is higher than in the case of other vibration modes. Furthermore, sensitivity analysis with respect to the applied current, frequency, filling ratio, slag thickness, and insertion depth was performed. Calculated maximum sulfur content along the slag diameter decreased from 0.0754 to 0.0543 pct when the applied current increased from 1200 to 1800 A. The maximum sulfur concentration in the slag was reached at the frequency of 0.25 Hz and it increased with the increase in the filling ratio from 0.38 to 0.54. On the other hand, when the thickness of the slag pool decreased, the maximum sulfur concentration also decreased from 0.0812 to 0.0473 pct. With the increase in insertion depth from 2.5 to 7.5 mm, the maximum mass fraction of sulfur in slag increased by 5 pct.
The transient three-dimensional (3D) full-coupled multi-physical fields in the Electroslag-Remelting (ESR) process with the vibrating and traditional electrodes have been compared in this paper. A ...mathematical model for simultaneously predicting the electromagnetic phenomenon, heat transfer, two phase flow and solidification has been established in the ESR furnace. Especially, the Joule heating and electromagnetic force are calculated by self-developed program based on the magnetohydrodynamic (MHD) model. The effects of the vibrating modes, such as horizontal and vertical vibration, on the heat transfer and MHD two-phase flow as well as solidification are clarified. The results indicate that the melting rating can be increased in the ESR process with vibrating electrode. The small-scale factory experiments are conducted and a reasonable agreement between the experimental observations and numerical results is obtained. The variation of temperature distribution dominated by the dropping behavior of the metal droplets is ordered and periodic. Particularly, the distinct variation of temperature distribution occurs beneath the bottom tip of the electrode. The horizontal vibrating ESR process can generate smaller metal droplets, which provide less energy (heat plus momentum) into the metal pool, constitute a shallower pool and a lower average temperature gradient. Moreover, with the increasing amplitude or frequency, the average temperature gradients for both cases decrease.
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