Molten Iron Flow Research Articles

Rapidly Rotating Magnetohydrodynamics and the Geodynamo

The problem of the geodynamo is simple to formulate (Why does the Earth possess a magnetic field?), yet it proves surprisingly hard to address. As with most geophysical flows, the fluid flow of molten iron in the Earth's core is strongly influenced by the Coriolis effect. Because the liquid is electrically conducting, it is also strongly influenced by the Lorentz force. The balance is unusual in that, whereas each of these effects considered separately tends to impede the flow, the magnetic field in the Earth's core relaxes the effect of the rapid rotation and allows the development of a large-scale flow in the core that in turn regenerates the field. This review covers some recent developments regarding the interplay between rotation and magnetic fields and how it affects the flow in the Earth's core.

Detection Method of Molten Iron Flow Velocity at Blast Furnace Taphole Combining Visual Perception and Jet Mechanism

Detection Method of Molten Iron Flow Velocity at Blast Furnace Taphole Combining Visual Perception and Jet Mechanism

Thermal Stress Analysis of Blast Furnace Hearth with Typical Erosion Based on Thermal Fluid-Solid Coupling

The life of the hearth is the main limiting link of the campaign of a blast furnace. As the equipment for holding molten iron in the furnace, the high-temperature molten iron is in direct contact with the refractory, which makes the refractory have a larger temperature increase. If the temperature gradient inside the refractory is large, it generates large thermal stress and causes the refractory to crack. Blast furnace gas and molten iron intrude into the gap, which directly causes melting erosion and other chemical erosion with carbon bricks. It aggravates the erosion degree of the furnace and seriously affects the production life of the furnace. Therefore, the furnace often occurs with different types of severe depression erosion in the late service of the blast furnace. In this study, the calculation model of the thermal fluid-solid coupling considering the molten iron flow and the solidification of molten iron was established. This calculation model was applied to study thermal stresses in the furnace with severe erosion. Based on the calculation model, the effect of blast furnace production parameters and deadman condition on thermal stresses in the furnace with severe depression erosion were analyzed, including tapping productivity, tapping temperature, cooling intensity, and deadman geometry. The research results are of great significance for prolonging the safe production life of blast furnaces.

A new monitoring method for the blocking time of the taphole of blast furnace using molten iron flow images

When to block the taphole is a concern in blast furnace ironmaking process. Currently, the blocking time of the taphole mainly depends on expertise, causing poor reliability of the blocking operation. Therefore, this paper proposes a new method to intelligently determine the blocking time using molten iron flow images. Firstly, a monitoring system is designed to obtain molten iron flow images at the taphole. Secondly, the blocking time monitoring problem is transformed into a classification problem of molten iron image to obtain tapping stages, and a novel image classification module, which further promotes the network’s representational ability by merging three feature extraction mechanisms in parallel, is proposed to accurately classify the images and obtain the tapping stages. Finally, a categorical correction model and a blocking time calculation model are constructed to obtain an accurate blocking time. Experimental results show that the proposed method can accurately monitor the taphole’s blocking time.

Polymorphic Temperature Measurement Method of Molten Iron After Skimmer in Ironmaking Process

In the ironmaking process, online and accurate temperature measurement of molten iron after the skimmer is an important problem that the steel industry is eager to solve. However, the different dust interference and the oxide layer covered on the molten iron flow make this problem not easy. To solve this problem, this article proposed a polymorphic temperature measurement method of molten iron after the skimmer. First, an infrared temperature measurement system is designed to capture the thermal images of molten iron flow after the skimmer. Second, considering that the dust has different interference states, the idea of polymorphism is introduced, and the interference states of dust are identified. Then, a polymorphic measurement model of the oxide layer is established to accurately measure the oxide layer temperature under different dust interference states. Finally, a polymorphic temperature measurement model of the molten iron after the skimmer is derived based on the heat transfer between the molten iron and the oxide layer. Industrial experiment results indicate that the proposed polymorphic temperature measurement method can accurately measure the temperature of molten iron after the skimmer and provide reliable molten iron temperature (MIT) data for blast furnace (BF) operators.

Mass Flow Measurement of Molten Iron From Blast Furnace, Based on Trusted Region Stacking Using Single High-Speed Camera

Accurately measuring the mass flow of molten iron at the bottom of a blast furnace is of great significance for energy savings and efficient operation in the iron making process. However, the lack of texture information on the surface of molten iron will severely limit the accuracy of conventional displacement reconstruction algorithms. To this end, this article presents a methodology based on trusted region stacking, which can estimate an accurate displacement distribution of the molten iron surface through automatic location, tracking, and stacking of the trusted region. Subsequently, a falling motion model of the molten iron was proposed, and combined with the displacement distribution of the molten iron surface, the accurate measurement of the molten iron velocity at the outlet of the swing nozzle was realized even if the image of the molten iron there is missing. Therefore, the mass flow of molten iron is determined with the a priori information of the outlet shape of the swing nozzle. Industrial experiments illustrate that the proposed method can stably and accurately measure the molten iron mass flow and estimate the weight of molten iron in the iron ladle.

Hot metal flow characteristics and its contribution to hearth erosion in the early stage of blast furnace campaign

Hot metal circulation is one of the most important factors for hearth erosion. In this article, both the production conditions reflected by production parameters and the actual erosion state are considered. A series of cases are set up to analyze the hot metal flow characteristics and its contribution to hearth erosion. The main results are as follow: (1) There are two asymmetric high-speed bands existed on both side of the taphole, which is caused by the inner shape of blast furnace hearth and will cause the erosion of blast furnace hearth. (2) The velocity inside the deadman has an obvious decrease from top to middle part and then keeps almost stable, especially at the edge of deadman. It is caused by the inhibition effect of molten iron flow around deadman, and may result in a slower update rate of deadman in the lower part as well as an increase of carbon unsaturation in the molten iron. (3) The velocity of line 4–5# around the bottom increases with the increasing of daily output, and decreases with the increasing of the depth of salamander. Therefore, in the early stage of the blast furnace campaign, a production process with high utilization factor will increase hearth erosion. (4) The inner shape of hearth and the distance between sidewall and deadman are the main factors affecting the flow rate of molten iron.

Compensation Method for Molten Iron Temperature Measurement Based on Heterogeneous Features of Infrared Thermal Images

Accurate temperature measurement of blast furnace molten iron is essential for regulating the furnace temperature. However, the dust interference at blast furnace cast field makes it difficult to measure molten iron temperature accurately using the infrared temperature measurement method. To reduce the influence of dust on the results of infrared measurement method, a compensation method using the heterogeneous features of infrared images is proposed in this article. First, the infrared image of the molten iron flow is divided into subregions, from which the subregions containing only molten iron are selected. Then, the statistic and the texture features influenced by dust are extracted from the selected subregions. Finally, the heterogeneous features are used as the compensation model input to estimate the measurement error of each subregion and compensate for the molten iron temperature. Experimental results demonstrate that the compensation method can significantly reduce the infrared measurement errors caused by dust and obtain accurate molten iron temperature.

Observation of Deadman Samples in a Dissected Blast Furnace Hearth

The actual state and packing condition of deadman in blast furnace (BF) hearth have always been a matter of great concern. For it directly affects thermal state of BF hearth and relates to the smooth operation and longevity of BF In this study, a commercial BF was dissected and then core drilling and image processing methods were used to obtain typical samples and characteristics of deadman. The results show that the deadman, with a radius of 80.09% of hearth radius, floated in hearth and surrounded by molten iron. The sample in horizontal direction has an average coke size of 28.04 mm and a void fraction of 0.52 while the vertical sample has an average coke size of 30.55 mm and a void fraction of 0.50. It should be noted that the average diameter of coke is the reference value which will be different depending on different assumptions. The coke size of vertical sample shows decreasing trendfrom topside to middle part and then keeps slight fluctuations.. And the void fraction in the middle of the vertical sample is the largest and gradually decreases toward both the upper and lower ends. Changes in these features of deadman are caused by the renewal of deadman and the flow of molten iron.

Temperature Measurement and Compensation Method of Blast Furnace Molten Iron Based on Infrared Computer Vision

The temperature of molten iron at the taphole of blast furnace (BF) is an important parameter that reflects molten iron quality and BF conditions. It is not easy to measure the temperature of molten iron at the taphole in real time. To achieve continuous and accurate detection of molten iron temperature (MIT) at taphole, this paper proposes a temperature measurement and compensation method of molten iron based on infrared computer vision. First, an infrared computer vision system is designed and installed to capture the infrared thermal images of molten iron flow at the taphole. Then, the molten iron flow area is determined by using image processing. Afterward, the temperature information of slag region is obtained to calculate the MIT based on threshold segmentation. Furthermore, considering the measurement error caused by dust, the texture features influenced by dust are extracted based on the defined temperature-level co-occurrence matrix and the neighboring temperature-level-dependence matrix, and a compensation model is established to compensate the measurement error based on ensemble neural network and support vector regression. Finally, considering that the MIT and the slag temperature are approximately the same at the taphole, the MIT at the taphole is acquired according to the slag temperature. Industrial experiments and applications demonstrate that the proposed method can measure the MIT at the taphole continuously and accurately and provide reliable MIT data for operators to control BF.

Temperature Measurement Method for Blast Furnace Molten Iron Based on Infrared Thermography and Temperature Reduction Model.

The temperature measurement of blast furnace (BF) molten iron is a mandatory requirement in the ironmaking process, and the molten iron temperature is significant in estimating the molten iron quality and control blast furnace condition. However, it is not easy to realize real-time measurement of molten iron temperature because of the harsh environment in the blast furnace casthouse and the high-temperature characteristics of molten iron. To achieve continuous detection of the molten iron temperature of the blast furnace, this paper proposes a temperature measurement method based on infrared thermography and a temperature reduction model. Firstly, an infrared thermal imager is applied to capture the infrared thermal image of the molten iron flow after the skimmer. Then, based on the temperature distribution of the molten iron flow region, a temperature mapping model is established to measure the molten iron temperature after the skimmer. Finally, a temperature reduction model is developed to describe the relationship between the molten iron temperature at the taphole and skimmer, and the molten iron temperature at the taphole is calculated according to the temperature reduction model and the molten iron temperature after the skimmer. Industrial experiment results illustrate that the proposed method can achieve simultaneous measurement of molten iron temperature at the skimmer and taphole and provide reliable temperature data for regulating the blast furnace.

Sensitive Influence of Floating State of Blast Furnace Deadman on Molten Iron Flow and Hearth Erosion

Sensitive Influence of Floating State of Blast Furnace Deadman on Molten Iron Flow and Hearth Erosion

Hartmann Newtonian radiating MHD flow for a rotating vertical porous channel immersed in a Darcian Porous Regime

Purpose– The purpose of this paper is to develop and correct the problem studied by Makinde and Mhone (2005) to a rotating vertical porous channel immersed in a Darcian porous regime in presence of a strong transverse magnetic filled and with the application of thermal radiation. In this investigation, the fluid is considered to be of viscous, electrically conducting, Newtonian and radiating and is optically thin with a relatively low density. Excellent agreement is obtained for exact solutions with those of previously published works.Design/methodology/approach– In this investigation, a closed form analytical method based on the complex notations for the velocity, temperature and the pressure is developed to solve the governing coupled, non-linear partial differential equations. The accuracy and effectiveness of the method are demonstrated.Findings– Interestingly observed that, the Lorentizian body force is not act as a drag force as in conventional MHD flows, but as an aiding body force and this will serve to accelerate the flow and boost the primary velocities. Due to the large rotation of the channel, the primary velocities are become flattered and shift towards the walls of the channel. With a rise in Darcian drag force, flow velocity and shear stress are found to reduce. Moreover, increasing thermal radiation and rotation of the channel strongly depress the shear stress, and maximum flow reversal, i.e. back flow is observed due to large Darcian resistance, thermal radiation and rotation.Research limitations/implications– The analysis is valid for unsteady, two-dimensional laminar flow of an optically thick no-gray gas, electrically conducting, and Newtonian fluid past an isothermal vertical surface adjacent to the Darcian regime with variable surface temperature. An extension to three-dimensional flow case is left for future work.Practical implications– Practical interest of such study includes applications in magnetic control of molten iron flow in the steel industry, liquid metal cooling in nuclear reactors, magnetic suppression of molten semi-conducting materials and meteorology and in many branches of engineering and science. It is well known that the effect of thermal radiation is important in space technology and high-temperature processes. Thermal radiation also plays an important role in controlling heat transfer process in polymer processing industry.Originality/value– The paper presents useful conclusions with the help of graphical results obtained from studying exact solutions based on complex notations for Darcian drag force, rotation of the channel and conduction-radiation heat transfer interaction by unsteady rotational flow in a vertical porous channel embedded in a Darcian porous regime under the application hydromagnetic force. The results of this study may be of interest to engineers for heat transfer augmentation and drag reduction in heat exchangers as well as MHD boundary layer control of re-entry vehicles, etc.

3D Dynamic Simulation and Optimization of Mammoth Desiliconization Converter for High-Quality Stainless Steel

A three-dimensional dynamic simulation model of the molten iron flow field was presented in the paper with Fluent simulation software. Different operating parameters combinations, including different oxygen lance locations, oxygen pressures and oxygen flows, different arrangements of bottom blowing holes, hole sizes, nitrogen pressures and nitrogen flows were studied. It is shown that the relative optimum value of the distance from top-blow gun to the molten iron surface is 1500 mm, and bottom blowing hole diameter is 20mm, there is no significant difference of the blowing effects found when comparing single ring arrangement with double rings arrangement of 8 bottom blowing holes with only bottom-blow, and the bottom-blow of inner ring is disturbed by top-blow when top and bottom combined blow. Optimized design results have been applied to the design and manufacture of the actual converter, the converter has been successfully used in plant. The actual production results indicate that the desiliconization precision can reach 0.05%, the content of Cr2O3 in the slag after reduction can be less than 2%, better than the technical requirements of 3%, and improve the recovery rate of the chromium. Compared with traditional desiliconization method by iron gutter and iron ladle, desiliconization by converter does not use compression residue agents and reduce the amount of desiliconization agents and slag, and improve the desiliconization efficiency and productivity.

Research on Molten Iron Vertical Flow Rate and Level Based on Dynamic Infrared Radiation and Time Intervals

In the foundry, it's difficult to measure the level of molten iron in pouring package and the flow of molten iron each pouring during casting control process, which will result in the control problem of over-pouring and under-pouring.So,a new measurement method about molten iron level and dynamic detection of vertical flow rate has been developed in this paper.The method is based on infrared radiation and time intervals under the state of vertical flow rate of molten iron. By analysing the flow rate of molten iron in the casting ladle taphole theoretically, building field experimental device and analysing experimental results, it shows that the proposed iron level measurement and dynamic detection of vertical flow rate based on infrared radiation and time intervals are feasible. And then it lays a foundation for controlling the flow of molten iron.

Dissection Investigation of Blast Furnace Hearth—Kokura No. 2 Blast Furnace (2nd Campaign)

Dissection investigation of blast furnace hearth was made at Kokura No. 2 Blast Furnace (2nd Campaign). Before blow-out, tracer response test was carried out in order to estimate the molten iron flow in hearth, and the measured data indicated that the depth of “effective” flow region of molten iron was extremely shallow. According to the result of the dissection investigation, the deadman was floating in hearth, and deadman coke was considerably degraded. Therefore, the poor permeability of the deadman is supposed to cause a downsize in the flow space of molten iron, which coincides with the prediction through the tracer response test. The numerical method to estimate the boundary shape of the deadman was developed by means of evaluating the stress field of the deadman in hearth. The calculated result was in reasonable agreement with the observed shape of deadman. In addition, based on the data obtained by analyses of the boring samples, the thermal equilibrium erosion shape of hearth refractory was evaluated by numerical simulation, and a good agreement to the observed shape was found.

On the applicability of the frozen flux approximation in core flow modelling as a function of temporal frequency and spatial degree

SUMMARY The secular variation of the geomagnetic field is due to flow of molten iron in the Earth’s core. One can invert for the flow at the core-surface, assuming that the magnetic field is frozen into the core fluid. The validity of the frozen flux approximation (FFA) depends on the scale length of the magnetic field and the period of core motions. A first-order quantitative assessment can be made by solving the induction equation for a spherical conductor oscillating in an ambient magnetic field. The period, at which the FFA holds, strongly decreases with increasing spherical harmonic degree of the ambient field. For degrees smaller than five, the flux of the ambient magnetic field can be considered as frozen-in for periods of more than a thousand years. For ambient magnetic fields of spherical harmonic degree 10 and higher, the FFA still holds up to periods of about a hundred years. However, the real situation in the core could be more complex if the field cannot be assumed as ambient but is generated by the flow itself.

Blast furnace campaign life relating to the productivity

The effect of blast furnace productivity on the erosion of the hearth wall and the campaign life was examined. First, the molten iron flow in the hearth was studied by a model experiment and an iron flow estimation model calculation. Next, the temperature distribution in the hearth wall was calculated by a heat transfer model, and the erosion of the wall and formation of the solidified layer were estimated. The study led to the erosion pattern during the blast furnace campaign life, which was verified by the actual furnace erosion pattern.

Mathematical Modeling of Iron and Steel Making Processes. Mathematical Model for Transient Erosion Process of Blast Furnace Hearth.

A mathematical model that can estimate the transient erosion process of the blast furnace hearth has been developed. This mathematical model can treat the molten iron flow, heat transfer and the brick/refractory erosion at the hearth. To verify the availability of the mathematical model, comparisons of computational final erosion profile of the hearth were made with the investigation results of the dissection blast furnace and computational results gave good agreement with the measured one. The effects of the distribution profile of the dripping molten iron flow rate into the hearth, the coke free layer size, production rate of the molten iron, thermal conductivity of the carbon brick and the fluid flow resistance through the coke packed bed were examined by using this mathematical model.

Evaporation of solids by laser pulses. I. Iron

The laser−induced vaporization of iron was studied using a quadrupole mass spectrometer detector. Neutral atoms emitted by thermal processes at the surface were of interest; energetic ions produced by a plasma near the surface were not. Conventional mode laser pulses served as a heat source and the characteristics of the pulses of vaporized atoms reaching the mass spectrometer were determined by time−of−flight analysis of the output signal from this device. The data agreed reasonably well with the predictions of an equilibrium model, in which transient surface vaporization is treated as a sequence of equilibrium stages at each of which Langmuir vaporization with unit condensation coefficient occurs. Agreement between theory and experiment failed at high laser energies because of the outward flow of molten iron from the spot struck by the laser. This cratering phenomenon invalidated the temperature calculation from which the vaporization rate was calculated.