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Heat transfer in steelmaking ladle refractories and steel temperature. A literature review
Abstract
The process of heat transfer in the steelmaking ladle refractories was investigated. Several techniques of modeling the heat loss were also discussed. Processes from continuous casting to optics were scheduled in the design of physical models. The thermal condition of the system was evaluated by thoroughly analyzing the experimental observations. Heat and mass transfer of the ladle system clearly projected the thermal stability along with the stratification parameters. Computation parameters of the on-line simulated system were also reported.
... As mentioned earlier, the temperature changes in the liquid steel are partially related to the ladle heat losses. Being aware of the ladle heat losses during the process step occurring prior to reaching the CC machine is essential to the temperature control of the liquid steel in industrial ladles [19][20][21]. Several studies have highlighted the impact of the heat losses on temperature predictions of the liquid steel [5,17,20,[22][23][24][25][26][27][28][29]. ...
... There are several phenomena that influence the heat losses of the steel. Radiation, conduction, and convection losses must be considered in order to determine the heat losses in the ladle [21,29,30]. The process steps and observed phenomena influencing the heat losses and temperature changes the most in the secondary metallurgy station are listed in detail below [20,21,[23][24][25][26][27][28][29][30][31]: ...
... Radiation, conduction, and convection losses must be considered in order to determine the heat losses in the ladle [21,29,30]. The process steps and observed phenomena influencing the heat losses and temperature changes the most in the secondary metallurgy station are listed in detail below [20,21,[23][24][25][26][27][28][29][30][31]: ...
The present work focuses on predicting the steel melt temperature following the vacuum treatment step in a vacuum tank degasser (VTD). The primary objective is to establish a comprehensive methodology for developing and validating machine learning (ML) models within this context. Another objective is to evaluate the model by analyzing the alignment of the SHAP values with metallurgical domain expectations, thereby validating the model’s predictions from a metallurgical perspective. The proposed methodology employs a Random Forest model, incorporating a grid search with domain-informed variables grouped into batches, and a robust model-selection criterion that ensures optimal predictive performance, while keeping the model as simple and stable as possible. Furthermore, the Shapley Additive Explanations (SHAP) algorithm is employed to interpret the model’s predictions. The selected model achieved a mean adjusted R2 of 0.631 and a hit ratio of 75.3% for a prediction error within ±5 °C. Despite the moderate predictive performance, SHAP highlighted several aspects consistent with metallurgical domain expertise, emphasizing the importance of domain knowledge in interpreting ML models. Improving data quality and refining the model framework could enhance predictive performance.
... A programação e o controle do processo têm um impacto direto na perda de calor do sistema panela-aço conforme a Revisão da Literatura de Fredman. (6) De acordo com Baker e Irving, (7) os passos e considerações necessárias para otimizar o controle do processo de fabricação do aço com alta produtividade são: i) prover uma carga corretamente balanceada; ii) minimizar o sobre-carregamento de escória entre a panela de fusão e panela de refino e iii) manter uma temperatura estrita entre as etapas de refino e lingotamento. ...
... La consideración de varias zonas, posibilita realizar un mejor diseño a partir de la búsqueda de las combinaciones de materiales que presenten los mejores comportamientos de los indicadores técnico-económicos.El diseño del revestimiento de este tipo de instalación, requiere incluir la protección de la carcasa contra la deformación para evitar el sobreconsumo de materiales por la reducción del espacio útil de trabajo(González R. et al, 2013). En este último aspecto, los laboratorios Bethlemhem Homer desarrollaron los métodos de una capa y dos capas para el cálculo de la interacción refractario-carcasa(Hlinka J, 1986, Fredman T, 2003, Chang W. et al, 2018, cuyos procedimientos de aplicación se muestran en el Anexo 3. ...
Se aborda el desarrollo de procedimientos efectivos de selección de
materiales refractarios, para el diseño de los revestimientos de las cazuelas de vaciado de acero mediante el modelado matemático de esta tarea de ingeniería como proceso de toma de decisiones, bajo un enfoque sistémico de análisis. La importancia de este tema, se relaciona con la persistencia en la actualidad de problemas relacionados con los elevados consumos demateriales y de recursos energéticos-financieros, como resultado de la baja eficiencia de los
métodos establecidos para la realización de esta actividad de diseño en el sector industrial.
La novedad de la investigación presentada en el campo del modelado, está dada por el perfeccionamiento de los modelos matemáticos de selección óptima de materiales refractarios y la obtención de procedimientos evolutivos que aportan poblaciones de soluciones eficientes, que se caracterizan por tener mejores valores de relación entre los indicadores de eficiencia.
Otro resultado importante a destacar, es la obtención de una herramienta computacional de diseño de revestimientos para el caso de las cazuelas de vaciado de acero con un alto valor metodológico en cuanto a las vías y métodos de análisis seguidos, los que pueden ser aplicados a otros casos de estudio
... Devido à importância do problema, vários autores despenderam esforços para conhecer e modelar o comportamento da temperatura do aço líquido durante as diversas etapas de refino e lingotamento. (3)(4)(5)(6)(7)(8) A base do modelo matemático para o cálculo da temperatura no lingotamento consiste em estimar o fluxo de energia do aço para os refratários da panela e para a escória. Conhecendo esses fluxos, é possível determinar a temperatura (média) do aço em função do tempo. ...
During secondary steelmaking and casting, the molten steel gradually loses temperature through ladle refractories and slag. Among other factors that may influence the behavior, the ladle geometry plays an important role. In the present paper, the relation between ladle diameter and steel thermal losses during secondary refining and casting were studied. A numerical model, to compute the steel thermal fluxes to refractories, was employed. A typical 100 t ladle, described in literature, was chosen for the reference data to simulations, where the rise and decrease in diameter were evaluated. The results show that the rise in diameter leads to a higher steel thermal losses. This happens because the increase in the metal-slag interface area and due to the fact that during the vacuum degassing the heat flow through this interface is much higher than others process stages.
A fully transient 3D CFD model of an industrial argon bottom-stirred ladle with two eccentric porous plugs was developed. The computational domain included molten steel, slag, air and refractory phases. The slag-air interface was set as a free surface to ensure that the influence of the flow and the heat dissipation at the slag free surface on the temperature of the molten steel can be considered simultaneously. As a result, the model reasonably predicted the velocity and temperature distribution of molten steel, heat losses from the top slag layer and the temperature distribution in the refractory walls due to bottom gas injection. Previous numerical models on heat transfer in ladles have either neglected bottom gas injection, assumed a constant heat flux through the top slag layer or assumed a flat surface. The current mathematical model overcomes the previous limitations, it is capable to predict fluid flow and temperature distribution under transient conditions comparing a flat and a free surface. It is shown that the assumption of a flat surface leads to errors in the numerical predictions, it also predicts heat losses by the top slag surface and the refractory walls.
A dynamic one-dimensional mathematical model was developed for predicting the thermal state of a steelmaking ladle. The model is intended to be used in process control applications, in which fast computational times are desirable alongside model accuracy. The calculation domain was discretized using the finite difference method, and time integration was performed using both the implicit Euler and Crank–Nicolson methods, the performances of which were compared. The model was implemented in Python programming language and validated using data from our own measurements and other studies available in the literature. The results indicate that the model can reproduce the measured temperature evolution of the ladles within 5°C at best. The worst performance was observed during cooling, where the model underestimates the temperature at the innermost measurement point by up to 200°C. With computation times of around 16–23 s for one hour of simulation, the model is computationally sufficiently fast for online applications.
Esfahan Steel Company is one of the major steel companies in Iran producing 2.2 Million tons of steel annually. It is important to steel makers that steel vessels have a long life. In this regard comprehending the thermo-mechanical behaviour of refractories and their strength against harmful thermal shocks is necessary. In the present work the thermo-mechanical loadings applied to the refractory and steel shell during preheating, stopping time before converter tapping and after converter tapping have been studied. The results show that working layers in the wall and bottom sections bear the maximum and minimum stresses respectively. Converter tapping into ladle causes more stress in the refractories than the other two steps. The maximum stresses in the steel shell were in the top of the ladle, which leads to deformations in this region.
In continuous casting, temperature control of liquid steel plays an important role in productivity, quality and ladle refractory life. In order to estimate heat loss during the steelmaking process, analysis of the transient thermal state of a ladle has been conducted using the computational fluid dynamics (CFD) software. The real geometry and operating condition of a commercial scale ladle at Ispat Inland Inc. have been used. At these steelmaking shops, the refractory supplies have been changed constantly and it is necessary to have a clear picture of the current thermal behavior of the new refractories during ladle cycles. Temperature distributions in the ladle refractories and liquid steel as well as temperature history and heat loss have been analyzed. Parametric studies have been performed to provide guidelines for the ladle operations.
Gunning materials are used as a dispensable protective layer to extend the tundish life. Their use however, affects the steel cleanliness by introducing steel reoxidation and exogenous inclusions. In the present work, the interaction between molten steel and three types of refractory, i.e. MgO, Al2O3, and MgO + 2MgO∙SiO2 based gunning materials (GM) have been investigated. Compared to MgO and MgO + 2MgO∙SiO2 GM, the Al2O3 GM exhibited better infiltration resistance to molten steel. The two phase MgO + 2MgO∙SiO2 GM was found to be less prone to steel infiltration than single-phase MgO GM. The compositional evolution of steel influenced by gunning material was experimentally measured and also predicted with thermodynamic equilibrium calculations. The steel cleanliness in terms of inclusion size, number density, area fraction and morphology was measured and evaluated. Although large Al2O3/AlTiOX inclusions were formed through the erosion of Al2O3 GM, the use of Al2O3 GM resulted in an improved steel cleanliness due to its lower content of reducible compounds compared to that of MgO and MgO + 2MgO∙SiO2 GM.
A mathematical model for predicting the melt temperatures in the ladle and in the tundish during continuous casting has been developed. First of all, a chain of models was created for the following stages of the ladle cycle; the preheating of the empty ladle, filling of the ladle, period in the ladle furnace, waiting period prior to casting, the casting period, and, finally, the free cooling period of the empty ladle. Models, written in CFD code, were used in sequence so that each simulation continued from the results of the simulation of the previous stage. An intermediate model was constructed to estimate the outlet temperature of melt drained from the ladle. Then the work was continued by performing simulations in the tundish, using as input the temperature of the simulated melt feed from the ladle and, as an initial condition, the temperature field of the remaining melt in the tundish. The final model "TEMPARV3" was created and tested by means of measured tundish data received from a steel plant. By means of statistical analysis the coefficients of correlation between the test data and model data at the start, in the middle period, and at the end of casting were calculated to be 0.9, 0.92 and 0.87, respectively. So, the most effective predictive power of the model in the tundish by means of a sequential casting schedule is realized during the middle period of the casting process. The model is applied interactively by a user interface, which expresses the predicted melt temperatures numerically and with graphical curves. The predictive model can be used off-line as a tool for scheduling the stage operations in advance. The program may be utilized on-line to estimate the superheat needed and to control periods of the operation. In extreme cases, when the model alerts the operator about the danger of superheat loss having a critical effect on casting, the operator has a chance to take adjustment measures. In addition to production work, the model could be of benefit for studying changes in operating parameters, for training operators, and for use as a "low-cost computational pilot plant" in process development in general.
In order to realize stable production in the steel industry, it is important to control molten steel temperature in a continuous casting process. The present work aims to develop a gray-box model that predicts the molten steel temperature in the tundish (TD temp). In the proposed approach, two parameters in the first-principle model, i.e., overall heat transfer coefficients of ladle and tundish, are optimized for each past batch separately, then the relationship between the two parameters and measured process variables is modeled through random forests (RF). In this inner gray-box model, the statistical models update the physical parameters according to the operating condition. To enhance the accuracy of TD temp estimation, another RF model is developed which compensates errors of the inner gray-box. The proposed approach was validated through its application to real operation data at a steel work.
Resumo O objetivo do presente trabalho consiste em estudar o comportamento térmico das panelas durante as etapas do ciclo operacional utilizando modelos de transferência de calor e simulação computacional. A partir dos resultados do estudo se procurou fazer modificações com o intuito de diminuir as perdas de energia calorífica durante as etapas do processo produtivo. Através da modelagem matemática, medições na planta e simulações computacionais foram determinadas as quedas de temperatura e perdas de calor das panelas. A partir daí foram propostas mudanças operacionais e físicas que após testes práticos e ou simulações computacionais se mostraram eficientes para a diminuição das perdas caloríficas e menor consumo de energia elétrica no forno-panela. Palavras-chave: Panela de aciaria; Simulação computacional; Controle da temperatura em panelas; Ciclo operacional de panelas. COMPUTATIONAL SIMULATION OF LADLES OF STEELMAKING SINOBRAS S.A. Abstract The aim of this work consists in studing the thermal behavior of ladles during steps of the operating cycle using heat transfer equations and computational simulation. From the study results sought to make improvements in order to reduce the loss of heat energy during steps of the production process. Through mathematical modeling, measurements in the plant and computational simulations were determined the temperature drops and heat losses. Therefore were proposed operational and physical changes that after practice tests and or computational simulations proved to be efficient for the reduction of heat loss and lower consumption in the ladle furnace.
In this study, exergy analysis and efficiency estimation were applied to a ladle preheating process. The analysis was performed on a 25 ton capacity ladle. In the experiment, thermocouples had been installed to the ladle refractory at several positions in order to measure temperature of the refractory. Then, the obtained data was used to analyse energy and exergy balance of ladle preheating process. Efficiency of a conventional and regenerative burner, which is operated on heavy oil was defined. In this analysis, the first preheating of a ladle performed to estimate the burner efficiency. The results showed that the exergy efficiencies of the conventional burner and the regenerative burner are equal to 19.38% and 22.86%, respectively. In addition, the exergy destruction of the conventional burner and the regenerative burner are equal to 62.88% and 66.48%, respectively.
In this study, the main aspects found in the literature about refractories corrosion were reviewed, evaluating the feasibility of certain tests and relating them with experimental results. In the first part of this work, the main properties of the microstructure of the refractories were discussed, such as aggregates and the matrix, including the binder phase (resins or pitch), presence of carbon, porosity, additives and anti-oxidants. In this second part, the remaining aspects of corrosion, such as physical and chemical properties of refractories, slag characteristics and operating conditions are discussed, linking the theory with data from industrial practice. Specifically, it was analyzed the refractory from slag-line of steel ladle.
A mathematical model and an experimental system are constructed to measure the high temperature with a CCD sensor. An experiential formula is found and the temperature distribution around the Molybdenum bar is obtained.
To realize stable production in the steel industry, it is important to control molten steel temperature in a continuous casting process. The present work aims to provide a general framework of gray-box modeling and to develop a gray-box model that predicts and controls molten steel temperature in a tundish (TD temp) with high accuracy. Since the adopted first-principle model (physical model) cannot accurately describe uncertainties such as degradation of ladles, their overall heat transfer coefficient, which is a parameter in the first-principle model, is optimized for each past batch separately, then the parameter is modeled as a function of process variables through a statistical modeling method, random forests. Such a model is termed as a serial gray-box model. Prediction errors of the first-principle model or the serial gray-box model can be compensated by using another statistical model; this approach derives a parallel gray-box model or a combined gray-box model. In addition, the developed gray-box models are used to determine the optimal molten steel temperature in the Ruhrstahl–Heraeus degassing process from the target TD temp, since the continuous casting process has no manipulated variable to directly control TD temp. The proposed modeling and control strategy is validated through its application to real operation data at a steel work. The results show that the combined gray-box model achieves the best performance in prediction and control of TD temp and satisfies the requirement for its industrial application.
A temperature prediction model has been developed for controlling the casting superheat temperature. For ease of implementation, the model is intentionally made simpler having a combination of a one dimensional heat transfer model and a simple regression model. The model is based on the fact that the BOF temperature of the liquid steel along with the bath cooling behaviours controls the aimed casting superheat temperature. Starting with the steel liquidus temperature and calculating the required steel temperature backwards throughout the process line gives the targeted BOF tap temperature. The on-line picking up of actual data helps the model to predict for the next stage more accurately in forward direction. Based on the predicted steel temperature, plant operators can take any necessary corrective action like additional ladle heating and extra/reduced argon stirring to ensure the aim final ladle/tundish temperatures at the casting are achieved.
The heat transfer in a steelmaking ladle was studied. The evaluation of heat transfer of the steel was performed by measuring steel temperature in points including all refining steel process. In the ladle, the temperatures in the refractories and the shell were also measured. To evaluate the thermal profile between the hot and cold faces of the ladle in the slag line position, an experiment which shows the importance of thermal contact resistance was carried out. Higher heat losses in the tapping and the vacuum were verified. The temperature measurements of the ladle indicate distinct thermal profiles in each stage of steel refining. Moreover, as each stage of the process depends on the previous one, the complexity of the ladle thermal control is incremental. So a complete model of heat losses in the ladle is complex.
After the ladle furnace treatment, the steel continually loses temperature due to several factors: ladle refractories, slag, alloy additions, tundish operation etc. A considerable number of research studies seek the control and evaluation of these losses, since they determine the steel temperature at the end of ladle furnace treatment. The present work demonstrates the application of a mathematical model on the steel temperature evaluation during the ladle drainage. The simulated scenarios account for different casting velocities, bubbling times and two types of refractories. The results show that the temperature loss during casting can be predicted employing the mathematical model, reducing the uncertainty of the final ladle furnace temperature, bringing to a better overall efficiency.
A statistical model for predicting the liquid steel temperature in the ladle and in the tundish is devel-oped. Given a large data set in a steelmaking process, the proposed model predicts the temperature in a seconds with a good accuracy. The data are divided into four phases at the mediation of five temperature measurements: before tapping from the converter (CV), after throwing ferroalloys into the ladle, before and after the Ruhrstahl-Heraeus (RH) processing, and after casting into the tundish in the continuous cast-ing (CC) machine. Based on the general state space modeling, the bootstrap filter predicts the tempera-ture phase by phase. The particle approximation technique enables to compute general-shaped probability distributions. The proposed model gives a prediction not as a point but as a probability distribution, or a predictive distribution. It evaluates both uncertainty of the prediction and ununiformity of the temperature. It is applicable to sensitivity analysis, process scheduling and temperature control. KEY WORDS: statistical modeling and simulation; liquid steel temperature control; general state space model; bootstrap filter; steelmaking.
Numerical experiments were performed on fluid flow and heat transfer in 107-tonne steel ladles by 3-step implementations of numerical models. In the first step, a 1-dimensional numerical model was used to predict heat conduction fluxes through the ladle wall, bottom and top slag layer. In the second step, by means of computational fluid dynamics (CFD) modelling and employing the predicted heat loss fluxes as thermal boundary conditions, a 2-dimensional CFD model was applied to simulate natural convection in steel ladles during the holding period before teeming. In the third step, a 3-dimensional CFD model was implemented to further simulate fluid dynamics in the same ladles with drainage flows during teeming. Using these mathematical numerical models, the bulk cooling rate of the steel melt, the extent of thermal stratification during holding and the steel stream temperature during teeming were investigated for 2 types of 107-tonne steel ladles lined, respectively, with alumina and spinel in walls. In these investigations, the following 4 parameters were considered: (i) ladle lining inside surface (hot-face) temperature before tapping, (ii) top slag layer thickness, (iii) holding time and (iv) teeming rate. An important result of these investigations is that the concerned parameters all significantly influence the steel stream temperature during teeming, and the differences in teeming stream temperatures among different ladles, caused by these parameters, can be up to 20°C, which may be essential to temperature control in tundishes during continuous casting.
The article presents numerical simulations of fluid flow and chemical homogenization of liquid steel in gas-stirred ladle with two asymmetric porous plugs. In this study mixing time is analyzed as a function of porous plug location. All calculations were carried out by commercial computer program Fluent using k-ε turbulence model. Results show the velocity vectors of liquid steel and tracer concentration field after alloy addition. Numerical calculations were used to get the mixing time of liquid steel as a function of gas flow rate and porous plugs location.
The article presents numerical simulations of fluid flow and chemical homogenization of liquid steel in gas-stirred ladle with two asymmetric porous plugs. In this study mixing time is analyzed as a function of porous plug location. All calculations were carried out by commercial computer program Fluent using k-ε turbulence model. Results show the velocity vectors of liquid steel and tracer concentration field after alloy addition. Numerical calculations were used to get the mixing time of liquid steel as a function of gas flow rate and porous plugs location.
This paper describes the use of ladles in a billet casting plant that uses sponge iron for steelmaking in a continuous casting mill with four strands. In order to decrease the rates of ladle wear dolomitic lining is used which does not interact with steel.
In this paper attention is focused on ladle temperature and the mechanisms and magnitudes of heat losses from steel contained in a ladle supplying a continuous casting machine.
A theoretical and experimental investigation of the temperature evolution of liquid steel in the steelshop has been carried out in the French Iron and Steel Industry. An original model of temperature stratification in the ladle has in particular been developed. The results have been implemented as an operating guide in the Hagondange and Neuves-Maisons Works. This has led to a reduction of the dispersion of the steel temperature in the tundish by a factor of 2, making it possible to gain the full advantages of a ladle furnace for temperature control in the case of billet and bloom continuous casting.
To produce steels with improved metallurgical properties, basic refractories such as dolomite are preferable to traditional aluminosilicate refractories for lining teeming ladles. To take full advantage of dolomite ladles in the production of higher quality steels, a strict preheating schedule for heating these ladles after bricking and at the end of each teeming sequence must be devised. This paper highlights the development of a mathematical model to produce suitable preheating schedules for these conditions. The model predicts the development of temperature at various locations in the cylindrical walls of the ladle during preheating for various fuels, fuel rates, refractory configurations, and initial starting conditions.
The requirement for better temperature control of molten steel during teeming or casting necessitates an improved means to evaluate the thermal effects of different refractory materials and melt shop operations. Both steady- and unsteady-state heat transfer models are used to evaluate changes in ladle refractories and the effects on steel temperatures. Parameters evaluated include refractory type, the use of insulation, and the use of ladle covers. 10 refs.
A mathematical model is presented which evaluates the thermal state of the tundish and the time evolution of the steel temperature during the casting process, taking into account different operating conditions. The model was verified by experimental measurements carried out in a steelplant for continuous casting of blooms. There was good agreement obtained between measured and calculated temperatures.
Most steel plants are currently operating with 100% continuous casting, often in sequence. This gives an increased demand for accurate process control of both the steel temperature and the time schedule. A normal steel plant practice gives too large a difference from heat to heat regarding the steel temperature in the ladle and the tundish, often due to the varying heat content of the ladle lining. One common practice to obtain an accurate steel temperature control in the tundish is to build in temperature and time buffers in the ladle metallurgy schedule, resulting in increasing costs for the higher temperature in the furnace and lower productivity. The aim of this project has been to study the possibility of measuring the heat content of the ladle lining by a non-contact method. Plant trials have been carried out at a Swedish steel plant, where the heat content of the ladle lining was determined by measuring the lining time-temperature relation with a radiation thermometer. By using the measured heat content as the input in a simulation model, it has been possible to calculate the steel temperature lapse. The difference between the calculated and actual measured steel temperature has been acceptable, with a standard deviation of ±3.5°C. This shows that it is possible to use a non-contact temperature measurement in connection with a calculation model to predict accurately the steel temperature lapse in the ladle.
A process model has been developed, which allows to determine the tapping temperature of LD converter, required to ensure the desired casting temperature. The model takes into account both the thermal state influenced by the last charge sequence and the expected temperature losses of the new charge in the ladle and tundish.
The temperatures of the refractory lining have been determined theoretically with the aid of a heating-up model for steel casting ladles. Energy flow diagrams have been plotted thereby for varying heating-up time and different operating conditions, such as modification of gas type, air ratio and heat recovery. The heat flow rates in the ladle wall and bottom resulting from the relationship correspond to the respective heat losses of the melt. In this way it is possible to determine also the temperature variations of the melt as a function of the heating-up system. The results obtained by computation are compared with measured values.
In the initial planning for the installation of a new horizontal caster at Avesta Panteg, it was decided to utilise the existing ingot teeming ladles for liquid steel supply. However, with long casting times and a small ladle size, indications were that high superheats would be required with a risk of breakout and poor billet quality. Therefore, an extensive programme of work was undertaken to redesign the ladle refractory lining for heat retention and thereby minimise superheat during horizontal casting. To enable accurate predictions of liquid steel temperature loss in the ladle and tundish to be made for horizontal casting, mathematical models of the ladle and tundish were calibrated via instrumented ladle trials. These trials showed that the expected temperature loss in the ladle during casting with the original refractory configuration would be 87 K with a corresponding 92 K loss in the tundish. Further trials with ladle insulation and mathematical modelling of the ladle have resulted in an insulated ladle design which reduced the temperature loss in the ladle to 46 K. With increasing use of the caster, this has now been reduced to 20-30 K.
A mathematical model is established to calculate the temperature variation of steel melts in the ladle by heat flows in the ladle wall, the ladle bottom and the slag. The model permits the definition of the melt temperature, from tapping to the end of the pouring process, taking due account of larger quantities of alloys and additions as well as scavenging of the melt. The temperature profiles in the refractory lining can be computed. 12 refs.
Plant measurements were done for selected parameters, influencing the heat content in ladle lining and the steel in ladle, from tapping time to the start of casting. Temperature profiles in ladle lining were measured throughout the ladle cycle by thermocouples installed in the lining. Measured parameters, such as molten steel temperature and ladle lining temperature profiles at the start of the ladle cycle, were used as initial input to the heat balance simulation model TempSim. Calculated and measured temperatures were compared and the possibility of using the heat balance model TempSim for prediction of steel temperature was demonstrated. The results obtained show that it is possible to predict steel temperatures in ladle at arrival to the casting station with a standard deviation of ±3°. The agreement between measured and calculated lining sublayer temperatures is also good. Effects on the melt temperature in ladle of lining wear, length of tapping time, amount of slag tapped from the primary furnace and lining temperature profile were also highlighted in this work. In particular, ladle lining wear and the length of the tapping influence the steel temperature in the ladle considerably.
The temperature distribution in the lining of a 300 t steel casting ladle has been measured for the first part of a ladle campaign. The thermal behavior of the ladle in the various process stages of a ladle cycle, such as drying, tapping, ladle metallurgy, transport, cooling and heating up, has been investigated in detail. The energy stored in the lining varies during the ladle campaign as a result of energy transfer to the ambient and of energy absorption from the melt. The mean temperature of the lining increases generally up to the fourth cast and varies subsequently about an average value. This results in greater temperature decreases of the melts at the beginning of the ladle campaign due to the relatively low temperatures in the lining. Towards the end of ladle campaign, the higher ladle heat losses of the ambient due to the reduction of the wear lining thickness result in higher heat losses of the melt.
A new polarizing pyrometric temperature measuring technique has been developed and tested for measuring the temperatures of hot oxidized metal surfaces. It makes it possible to measure the true temperatures of semi-finished material in reheating furnaces at temperatures above some 800°C with an accuracy of ± 10 K.
The steel ladle has been transformed from a vessel that was primarily used to hold molten steel for teeming into a vessel in which complex metallurgical processes are performed prior to casting or teeming. At LTV Steel's Aliquippa Works in Aliquippa, PA, and at the Indiana Harbor Works, in East Chicago, IN, this transformation made it necessary to upgrade the refractory materials used to line the steel ladles. As a result, fireclay lined steel ladles were converted to variable thickness 70 percent Al//2O//3 lined ladles with MgO slag lines in both facilities. Ladle preheating facilities were determined to be a prerequisite for long-term use of these refractories due to significant differences in thermal properties. A transient thermal model was developed to simulate a ladle that supplies liquid steel to a continuous casting machine. This paper examines several of the factors that can cause steel temperature variability. The tap temperature must be adjusted to account for variations in these factors. The best practice requires consistency which is best attained by keeping the ladles hot.
A unique computer system for on-line ladle thermal tracking and the calculation and prediction of the temperature of liquid steel in the ladle and tundish has been successfully commissioned at the Scunthorpe Works of British Steel.
A two-dimensional mathematical model of steelmaking ladles is presented. The model can be used as a design tool, by which
a number of variables such as holding time, material choice, and refractory layer thicknesses can be studied with regard to
their influence on the steel temperature evolution during casting. In addition, the model can act as a decision support and
as a basis for automation of temperature control. Temperature measurements from an operational steelmaking ladle are compared
to simulation results obtained with the model, demonstrating its feasibility and applicability to steelmaking.
Modeling of the transient thermal state of metallurgical ladels is motivated by the need for estimating the drop in temperature
of the liquid metal in the ladle. On-line estimation of the state is required, since the same ladle is used in a number of
casting cycles with rapid changes in boundary conditions for the temperature field, and the conditions in the current as well
as previous cycles affect the thermal state. Although a large number of methods for the numerical solution of conduction-diffusion
partial differential equations have been developed, there are still advantages to keeping thermal field computations at a
relatively simple level, in contrast to the situation in the design process of ladles, where two-dimensional modeling may
be required. Extensive computations under nonverifiable boundary and initial parameter values are not especially suited for
real-time simulation of industrial processes. This article presents a novel approach to the solution of the one-dimensional
transient heat conduction problem applied to ladle linings, relying on classical analytical techniques in combination with
numerical methods. The performance of the model was validated by a comparison of predictions to thermocouple measurements
from the refractory of a steelmaking ladle during a campaign of 26 casting cycles. Reasonable agreement between the measured
and simulated variables could be established, which demonstrates the feasibility of the approach.
An abstract is not available.
Terä lämpö tilahallinta senkkakä-telyjen ja jatkuvavalun aikana. Technical course print, in Fin-nish
- E Kivelä
- Sipola
Kivelä E, Sipola M. Terä lämpö tilahallinta senkkakä-telyjen ja jatkuvavalun aikana. Technical course print, in Fin-nish, Jun. 1994. Tä Tulenkestävä Ter-a ¨steollisuudessa, PohTo, Oulu Finland.
Model for predicting the evolution of steel tem-perature in a continuous casting tundish on the basis of ex-pert knowledge
- M Sillanpää
Sillanpää M. Model for predicting the evolution of steel tem-perature in a continuous casting tundish on the basis of ex-pert knowledge. Report 91-1, Åbo Akademi University, Heat Engineering Laboratory, Biskopsgatan 8, FIN-20500 Åbo
Trends in caster operation, part 1. Iron & Steel-maker Sep
- Aw Cramb
Cramb AW. Trends in caster operation, part 1. Iron & Steel-maker Sep. 1989: 45.
Steel temperature control in the ladle in a high productivity BOF shop
- Minion Rl
- Leckie
Minion RL, Leckie CF. Steel temperature control in the ladle in a high productivity BOF shop. In: 5th International Iron and Steel Congress. Proc the 69th Steelmaking Conf. Iron & Steel Society 1986: 69: 335–343.
Measurement of ladle wall temperature to im-prove control of steel temperature in BOF plant
- C-E Grip
Grip C-E. Measurement of ladle wall temperature to im-prove control of steel temperature in BOF plant. In: 77th Steelmaking Conference Proceedings, Iron & Steel Society 1994: 77: March.
Temperature loss in liquid steel-re-fractory systems. Iron and Steel Engineer
- Hlinka Jw
- Miller
Hlinka JW, Miller TW. Temperature loss in liquid steel-re-fractory systems. Iron and Steel Engineer, Aug. 1970.
Heat losses and scull formation in Fe-Si and Si-metal ladles
- Kw Christensen
Christensen KW. Heat losses and scull formation in Fe-Si and Si-metal ladles. In: Electric Furnace Conference Proc.
Temperature drop in pouring ladles, part two
- Paschkis V Hlinka
- Jw
Paschkis V, Hlinka JW. Temperature drop in pouring ladles, part two. AFS Transactions 1957: 65: 276–281.
Thermal modelling of steel ladles
- Austin Pr O 'rourke
- Sl
- He
- Ql
- Aj
Austin PR, O'Rourke SL, He QL, Rex AJ. Thermal modelling of steel ladles. In: 75th Steelmaking Conference Proceedings, vol. 75, pp. 317–323.
A model for predicting the thermal history of a ladle of steel
- Hlinka Jw
- Aw Cramb
- Bright
Hlinka JW, Cramb AW, Bright DH. A model for predicting the thermal history of a ladle of steel. In: 68th Steelmaking Conference Proc. Iron & Steel Society 1985: 68: 35–46.
Modell zur ther-mischen Simulation von Stahlgiesspfannen
- H Pfeifer
- Fett Fn
- H Schä
- K-H Heinen
Pfeifer H, Fett FN, Schä H, Heinen K-H. Modell zur ther-mischen Simulation von Stahlgiesspfannen. Stahl und Eisen 1984: 104 (24): 1279–1287.
Ironmaking and Steel-making
- Saha Jk
- Ajmani
- Sk
- Chatterjee
Saha JK, Ajmani SK, Chatterjee A. Ironmaking and Steel-making 1991: 18 (6): 417–422.
Heat losses from liquid steel in the ladle and in the tundish of a continuous-casting installation
- R Alberny
- Leclercq
Alberny R, Leclercq A. Heat losses from liquid steel in the ladle and in the tundish of a continuous-casting installation.
Senkan lämpö häviö iden laskeminen
- Choné Mj
- Teyssier
Choné MJ, Teyssier F. Senkan lämpö häviö iden laskeminen. Technical Report RE 137, IRSID, Maizié-lé-Metz, Oct. 1973. Translated from French at Rautaruukki Oy, Finland.
Ladle temperature control during continuous casting
- Ma Omotani
- Lj Heaslip
- Maclean
Omotani MA, Heaslip LJ, Maclean A. Ladle temperature control during continuous casting. Iron & Steelmaker 1983: Oct: 29–35.
Thermal cycle model of ladle for steel temperature control in melt shop and its application
- Koo Ys T Kang
- Lee
- Ir
- Yk Shin
- Hy
Koo YS, Kang T, Lee IR, Shin YK, Gal HY. Thermal cycle model of ladle for steel temperature control in melt shop and its application. In: 72nd Steelmaking Conf Proc. Iron & Steel Society, Apr 1989: vol. 72.
Math-ematical model of thermal performance of steel pouring ladle. Steel in the USSR Feb
- Shklyar Fr
- Malkin Vm
- Va Korshunov
- Sovetkin
- Vl
Shklyar FR, Malkin VM, Korshunov VA, Sovetkin VL. Math-ematical model of thermal performance of steel pouring ladle. Steel in the USSR Feb. 1991: 21: 68–70.
Optimizing ladle cycling strat-egies
- F Mucciardi
- Grandillo
Mucciardi F, Grandillo A. Optimizing ladle cycling strat-egies. In: 74th Steelmaking Conf Proc. Iron & Steel Society 1991: 74: 757–760.
Thermal cycle of continuous steel casting ladles: a mathematical model for predicting the steel temperature during the tapping and the filling period
- A Gastó
- R Laura
- Medina
Gastó n A, Laura R, Medina M. Thermal cycle of continuous steel casting ladles: a mathematical model for predicting the steel temperature during the tapping and the filling period. Latin American Applied Research 1993: 195–200.