Tap Hole Research Articles

Numerical analysis of the heat transfer behavior of steel stream in the converter tapping

The present study investigated the flow dynamics and heat transfer behavior of molten steel during converter steel tapping. This research lays the groundwork for designing accurate post-furnace temperature models and enabling lower tapping temperatures. Considering the influence of slag and the Coriolis force on the process, a mathematical model was developed to characterize both the transient flow dynamics of molten steel within the converter and the heat dissipation of the steel stream in the air. Moreover, a physical model constructed based on similarity principles elucidated the impacts of standing time and the Coriolis force on the remaining steel volume in the converter at the moment of slag entrapment. Results showed that as standing time increased or tapping hole size decreased, the remaining steel volume in the converter decreased. When the Coriolis force was included, the percentage of remaining steel volume was lower compared to simulations without it. Numerical simulations precisely determined the trajectory of the steel stream in the air domain, facilitating improved coordination between the converter and the ladle. Furthermore, at a tapping temperature of 1700°C and a tapping hole size of 140 mm, heat loss of the steel stream in the air domain led to a temperature decrease of 1.02°C. Heat loss decreased with increasing hole size. Lowering the tapping temperature by 50°C could reduce the temperature decrease from the air domain by 0.1°C. Finally, the study proposes preliminary strategies for lowering tapping temperature.

Numerical simulation of basic oxygen furnace rotating tapping

The rotation speed of the basic oxygen furnace (BOF) and the shape of the tapping hole have an important influence on the amount of slag carryover during the tapping process. The CFD fluid simulation software Fluent is used to analyze the flow field of the 210 t BOF rotation tapping process. The results revealed that the amount of slag carryover in the early stage is the largest when the tapping hole inclination angle is 0° and the rotation speed is 1.0 r/min. The flow field analysis shows that this is caused by the fluctuation of molten steel and slag, which makes the slag flow into the tapping hole again. The case of a rotation speed of 1.2 r/min shows the least amount of slag carryover. By comparing the three kinds of tapping holes, it can be known that a reduction in the tapping hole diameter brought a decrease in yield loss and a decrease in amount of slag carryover. As the height of molten steel decreases, the shear stress on the tapping hole decreases. The increase in the diameter of the tapping hole increases the shear stress, which in turn increases the wear of the refractory material.

Fugitive Emission Characteristics of Fume and Dust from Short-Process Electric Furnace Tap Hole and Optimization of Dust Hood

Due to the advantages of a short cycle, low investment and low energy consumption per ton of steel, short-process electric furnace steelmaking is about to welcome a golden period of rapid development in China. During the operation of the electric furnace, a large amount of smoke and dust is generated. Most studies focus on organized emissions, and the impact of unorganized emissions in workshops on the environment cannot be ignored. This paper evaluates the thermal environment in the electric furnace steelmaking workshop based on the analytic hierarchy process and obtains the influence weight of the fugitive emission location. The mass concentration of dust at each measuring point increased by 1.17 mg/m3 on average, and the concentration of unorganized emission dust near the outlet was 23.572 mg/m3. The numerical simulation calculation model is established by the CFD method, a fixed initial jet velocity is set, the initial velocity of the ladle soot plume is changed, and the inclination angle, arrangement height and dust removal air volume of the dust hood are respectively adjusted in different tapping periods. The impact of simulation on the efficiency of dust collection for different dust removal hood configurations was investigated, considering variations in inclination angle, arrangement height and dust removal airflow. The optimal structural parameters for the dust removal hood were determined to be an inclination angle of 60° and an arrangement height of 2.4 m, and an optimal dust removal airflow was determined to be 110,000 m3/h. This study provides a theoretical foundation for engineering practice.

Impact of land slope, tree density and basal area on fire intensity in pinus merkusii plantation forest

Forest fires are not solely determined by the quantity and quality of plant debris as fuel, but also influenced by some extrinsic factors. This study aims to examine the effect of some factors (slopes, tree density, and tree basal area) on the intensity of forest fires. The study was conducted in a 1 ha (100m x 100m) plot in the Pinus merkusii plantation 10 months after the fire. The plot was divided into 10 m x 10 m subplots, therefore there were 100 subplots. Each tree over 5 cm in diameter found in the plot was numbered consecutively, recorded its species name, measured its diameter, and determined whether it was alive or dead. The slope level in each subplot was measured. Multiple regression analysis was used to detect the influence of slope level, tree density, and basal area on the number of dead trees in each subplot. Results show that slopes, tree density, and basal area influenced proportionally the intensity of forest fires (R2 = 0,507; p<0.05). However, when the partial analysis was applied to detect the influence of each class factor, not all of the classes were found significant. These results reveal that there are several other factors not measured in this study that also influence fire intensity, which we suspect are tapping holes and tree diameter.

Desain Prototype Alat Filtrasi Sederhana dari Limbah Galon Air untuk Pembuatan Penyaringan Air Rumah Tangga

This study reports on the utilization of gallons of water used as containers for household-scale water purification filtration devices. The method of making a filtration device is by making a tap hole (outlet) at the bottom of the gallon and then putting in a filter material consisting of gravel, fine sand, charcoal, coarse sand, sponges, and palm fibre. A water filtration system by entering the water in the top hole of the gallon and the filtered water results are located at the bottom of the gallon that has been given a faucet. Based on the results of this study, it is shown that a gallon waste water-based filtration system is effective in the water filtration process at housing X in Kendari City. Test parameters consisting of turbidity, color, total dissolved solids (TDS), acidity (pH), and iron (Fe) content showed that the decrease in content that occurred in each turbidity test was 56.77%, color 33.33%, TDS 33.61%, the pH level increased by 4.21% (7.37 to 7.68) due to the effect of reduced levels of carbon dioxide (CO2) in water from the filtration process and categorized as water that is suitable for health. Fe levels did not change significantly, where there was an increase of 1.2% (25.7 × 10-4 mg.L-1 to 26.0 × 10-4 mg.L-1). The results of this study illustrate that gallons of water waste can be used as a material for making simple filtration equipment for household-scale water filtration processes.

Conceptual Tapping Model of Mn-Ferroalloy Furnaces

The tapping process of submerged arc furnaces, like the Mn-ferroalloy production process, is when you drain the liquid metal and slag from the furnace. The optimal tapping process is when slag and metal is drained from the furnace at the same rate as it is produced, and the slag and metal is being separated in the post-tap hole process. Industrially, this is not always the case. Based on published articles, this paper discusses the total tapping process that contains the consecutive steps of flow from back electrodes to the tap electrode and flow from the tap electrode through the tap hole and runner, and into the ladle system. It focuses on an overall summary of which elements may affect the tapping; however, it should be noted that this is not a mathematical model. The main information is regarding materials and zones in the furnaces, as well as knowledge from computational fluid dynamics (CFD) modeling work.

STUDY ON A TWO-PHASE LOW-TEMPERATURE MODEL OF THE FEATURES OF METAL TAPPING IN BASIC OXYGEN FURNACE

The paper shows the results of a study of the influence of the cut-off method of the slag by using destructible plugs on the quantitative indicators of the redistribution of slag and metal in the steel ladle during the metal tapping operation from the converter. The laboratory setup simulates a real 160-ton industrial top-blown oxygen converter, and a steel ladle at a scale of 1:18 has been used to fulfill the study. Water was chosen as a liquid steel imitator, and machine oil was chosen for slag with parameters that ensure the similarity of physical parameters in the metal-slag system. The physical modelling of the tapping process of a two-phase converter bath in the case of a destructible plug in the tap hole compared to the tapping option without it showed a significant positive effect of the presence of the plug in the initial period from the moment the converter is tilted.

Numerical analysis of coal size influencing the performance and slag flow characteristics of gasifier based on a comprehensive model

A comprehensive char gasification model based on random pore model with correction factor η is established to depict the char conversion process for entrained-flow gasification. The new comprehensive model uses advanced correlations for char gasification process parameters, including the correlations of a simplified multicomponent molecular diffusion, the evolution of particle size and density, char specific surface area and char thermal deactivation. A one-dimensional slag flow model coupled with the particle capture model is used to describe the deposition, flow and heat transfer process of the molten slag on the wall of HNCERI (Huaneng Clean Energy Research Institute) gasifier. The species mole fractions, carbon conversion efficiency, outlet temperature and the wall heat loss of the gasifier under the baseline are compared with the operating data. The simulation results indicate that the comprehensive model has sufficient accuracy to model the multiphase reactions and slag flow characteristics of HNCERI gasifier. The effect of coal size on exit gas temperature, detailed char heterogeneous reactions, gasification performance and slag flow characteristics of the gasifier are studied. Results show that, as coal size increases from 10 μm to 320 μm, the volume average rate of C + CO2 drops from 0.0095 to 0.0035 kmol/m3·s and C + H2O increases from 0.0064 to 0.012 kmol/m3·s at the first stage, and the carbon conversion efficiency at the first stage decreases from 99.72 % to 93.42 % while that at the second stage increases from 65 % to 93 %. The increase of coal size with values<80 μm has none significant influence on the formation of slag in the gasifier. With coal size further increasing, the formation of slag is highly promoted and thereby results in a rapid increasing thickness of the solid and liquid slag at the slag tap hole. An optimum coal size might be<80 μm for the first stage while an appropriate increase of coal size at the second stage is beneficial to improve carbon conversion efficiency.

The study of the effect of gas-phase fluctuation on slag flow and refractory brick corrosion in the slag tapping hole of an entrained-flow gasifier

The effects of gas-phase fluctuation on the brick corrosion process were studied in this work in order to investigate the corrosion mechanism of refractory brick in the slag tapping hole. The results explained the reason for the low service life of the refractory brick of the slag tapping hole in the commercial gasifiers. It was found that when the low-frequency fluctuation changed to the high-frequency fluctuation, the brick corrosion rate decreased gradually. Compared with the gas-phase velocity fluctuation, the gas-phase temperature fluctuation had a more significant influence on the brick corrosion rate. • The effect of gas temperature and velocity fluctuation on slag flow was studied. • Low-frequency fluctuation had a significant effect on the brick corrosion rate. • The brick corrosion rate increased with the increase of temperature fluctuation. The service life of refractory brick in the slag tapping hole of the entrained flow gasifier was significantly lower than that in other locations. It was critically important to study the corrosion mechanism of refractory brick in the slag tapping hole for guiding industrial production. Considering the complex flow field in the slag tapping hole, the influence of gas velocity and temperature fluctuation on the service life of refractory brick was investigated in this study. The results showed that the slag flow characteristics periodically changed with the gas temperature and velocity fluctuations. The brick corrosion rate increased with the decrease of fluctuation frequency. Compared with the gas-phase velocity fluctuation, the gas-phase temperature fluctuation had a more significant influence on the brick corrosion rate. When the fluctuation frequency was 0.01 Hz and the gas temperature fluctuation amplitude was 200 K, the corrosion rate of refractory bricks increased by 25%. It could be concluded that the fluctuation of gas-phase temperature was the main cause for the low service life of refractory bricks in the tapping hole.

Study on galling behaviour of HiPIMS deposited Mo/DLC multilayer coatings at ambient and elevated temperature

Galling has been a severe concern in oil – gas, automotive, and nuclear sectors. SS 304 steel is used in these industries despite its low galling resistance because it possesses good corrosion resistance properties. The threads of bolt, nut or a tapped hole and fasteners made of SS 304 experience severe damage due to galling or cold working. Therefore, the galling characteristics of the coated SS 304 samples were studied against the uncoated counterpart. A multilayer coating of molybdenum (Mo) and diamond like carbon (DLC) was deposited through dual sputtering using a high power impulse magnetron sputtering (HiPIMS) power source for graphite target and pulsed DC power source for Mo target. The Mo/DLC multilayer coating was optimized for antiwear and low friction properties. The evaluation of friction properties was done through a nanotribometer. The galling samples of SS 304 steel were prepared following the ASTM G196 standard, and the optimized coating was deposited on the galling samples. The adhesion strength of the coating was analyzed with the help of a nanoscratch tester. The galling behavior of coated and uncoated samples was investigated at room temperature (RT) and 300 °C. Galling damage was quantified by calculating the galling area on the galled sample. Image processing and computer vision tools were used to calculate the galled area. The tribopair having coated (Mo/DLC multilayer coating on SS 304) and the uncoated sample (SS 304) showed lower galled area than the tribopair containing both uncoated samples in every test conditions. At RT the coated sample failed at 15 MPa, whereas the uncoated samples failed at 5 MPa. Similar type of results were obtained when the samples were tested at 300 °C. The characterization of the coating and the mechanism of galling were studied in detail with the help of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nanoindentation, stereo-zoom optical microscopy, and scanning electron microscopy (SEM).

Numerical Simulation on the Effect of Burner Bias Angles on the Performance of a Two-Stage Entrained-Flow Gasifier.

A 2000 t/day HNCERI (Huaneng Clean Energy Research Institute) entrained-flow pulverized coal gasifier suffers from the problem of a high ash–slag ratio. An appropriate bias angle of the burners is the key to solve this issue for the gasifier with a specific structure. A random pore model considering bulk and pore diffusion effects was extended by user-defined function to describe the gasification reactions. The simulation of the gas flow and char gasification characteristics under different bias angles (0, 1.5, 2.5, 3.5, and 4.5°) of the four burners in the first stage was conducted. The simulation results showed favorable agreement with the industrial data. The evaporation, devolatilization, and char oxidation mainly occurred in the first-stage jet zone, and the upflow and downflow zones are dominated by the gasification reactions. The bias angles of the burners mainly affect the scale of gasification reaction zones. As the bias angles increased from 0 to 4.5°, the gas temperature at the slag tap hole decreased from 1880 to 1500 K. The carbon conversion efficiency of the first stage decreases and that of the second stage increases with the bias angle increasing. An optimal bias angle of 2.5° is recommended for the HNCERI gasifier with a total carbon conversion efficiency of 98.16%.

Hygienic behavior of bees as an element of sterility in the production of environmentally friendly products

Beekeeping in Russia has been widespread for a long time and almost everywhere, a traditional and significant branch of the country’s agriculture. In the Russian Federation, as in most countries, beekeeping is mainly practiced by amateurs. In 2019, according to government statistics, there were about 4.0 million bee colonies in the country, with more than 90% of them in the private sector. One of the factors of high productivity of bee colonies is the hygienic activity of individuals. The behavior of the bees in maintaining cleanliness and hygiene in the hive is astonishing. Not only the honeycomb, but even the walls and floor of the hive are always kept neat, polished with propolis. Garbage falling to the bottom of the hive is immediately thrown out through the entrance. Moreover, large litter, for example, the corpse of a bee, is pulled out by the orderlies onto the boarding board, and, grabbing it with their legs, take off to carry it away from the hive. Worker bees sweep small debris out of the hive with their fan wings, like brooms, and even brush dust particles to the tap hole. Sterility in a honey bee nest can be compared to an operating room in a modern clinical hospital.

Experiments and simulations on a cold-flow blast furnace hearth model

The blast furnace hearth plays an important role in the operational stability and lifetime of the reactor. The quasi-stagnant bed of coke particles termed the deadman undergoes complex interaction with the flowing hot metal, and remains largely ill-understood. In this work, a cold model blast furnace hearth is presented, and studied using both numerical and experimental techniques. Magnetic Particle Tracking (MPT) is used to investigate the individual particle behaviour within the cylindrical, opaque bed. At high liquid holdup, the particle bed was found to alternate between floating and sitting states, following the liquid level during the tapping and filling cycle. This bed motion was found to induce a migration of particles, thereby slowly renewing the deadman. The rate of horizontal migration increases with the vertical bed amplitude, and the renewal of particles is concentrated around the opening of the tap hole. No direct influence of the coke-free space on the tapping rate was found in these experiments. Instead, the disturbance of the packing in front of the tap hole was observed to lead to a higher tapping rate. Additionally, a coupled numerical framework is presented, in which Computational Fluid Dynamics (CFD), the Volume of Fluid (VOF) method and the Discrete Element Method (DEM) are combined. A simulation set-up is presented which closely replicates the experimental conditions. The position and movement of the floating bed are found to be well-predicted by the VOF/CFD-DEM model. Particle trajectories are presented, and migration of particles within the deadman is observed. Alongside the particle motion, the liquid flow pattern during draining of the vessel is visualised. It is concluded that a coke-free space underneath the deadman significantly impacts the shape of the liquid flow pattern, which affects the erosion processes within the blast furnace hearth.

Determining criterion of the operating temperature in the refractory brick entrained-flow gasifier based on the coal viscosity characteristics and slag flow process

Entrained flow gasification technology is currently widely used in the coal chemical industry. However, the selection of candidate coal for achieving smooth slag discharge is significantly limited. Herein, the temperature distribution in the slag tapping hole of the refractory brick lining gasifier was analyzed. The effect of the slag viscosity-temperature characteristics on slag discharge behaviors was evaluated. Specific theoretical criteria rather than empirical estimation were proposed for selecting the operating temperature and candidate coal, which were important for industrial production. The results showed that the temperature in a localized area of the slag tapping hole was very low in current refractory-scheme, which induced the formation of solid-slag. The slag viscosity-temperature characteristics were found to be the key factors influencing the slag discharge process. Moreover, the operating parameters including the ‘sensitive characteristic temperature’ and ‘no-solid slag characteristic temperature’ were proposed, in which the temperature range was optimal for different slags.

Tapping stream tracking model using computer vision and deep learning to minimize slag carry-over in basic oxygen furnace

&lt;abstract&gt; &lt;p&gt;This paper describes a system that can automatically determine the result of the slag dart input to the converter during tapping of basic oxygen furnace (BOF), by directly observing and tracking the behavior of the pouring molten steel at the tapping hole after the dart is injected. First, we propose an algorithm that detects and tracks objects, then automatically calculates the width of the tapping stream from slag-detection system (SDS) images collected in real time. Second, we develop a time-series model that can determine whether the slag dart was properly seated on the tap hole; this model uses the sequential width and brightness data of the tapping stream. To test the model accuracy, an experiment was performed using SDS data collected in a real BOF. When the number of sequential images was 11 and oversampling was 2:1, the classification accuracy in the test data set was 99.61%. Cases of success and failure of dart injection were quantified in connection with operation data such as ladle weight and tilt angle. A pilot system was constructed; it increases the reliability of prevention of slag carry-over during tapping, and can reduce the operator's workload by as much as 30%. This system can reduce the secondary refining cost by reducing the dart-misclassification rate, and thereby increase the productivity of the steel mill. Finally, the system can contribute to real-time process control and management by automatically linking the task of determining the input of darts to the work of minimizing slag carry-over in a BOF.&lt;/p&gt; &lt;/abstract&gt;

Development of a system for detecting and notification incomplete tapping of cast iron from a blast furnace based on computer vision methods

This study describes a method for detecting incomplete cast iron tapping in blast furnace production using computer vision. Incomplete cast iron tapping is a violation of the technological process and can slow down or stop the work of a metallurgical plant, which will lead to economic losses, therefore, the task of detecting incomplete cast iron tapping and notifying the operator of it is relevant. A method for detecting incomplete tapping was developed, based on the use of a neural network detector that detects a jet of cast iron in the tapping hole immediately before the tapping is completed. A dataset was assembled for training a neural network and software was developed to implement the method. An additional method for detecting incomplete tapping was developed, which is based on counting the number of sparks that appear during the subsequent cast iron tapping with the help of computer vision. The software implementing this method was developed, the threshold value of sparks was determined, upon reaching which a notification of the problem is generated. The universal video warning notification system «Empty display» was developed. The developed systems were implemented and tested at public joint-stock company (PJSC) Severstal in the agglomeration and blast-furnace coke production site. Warning notifications were correctly generated in 98% of cases.

3-D printed injection system for capillary electrophoresis.

Commercial systems for capillary electrophoresis are designed for the unattended analysis of several samples, and are usually large, complex, and expensive. We report a compact system for manual injection of a single sample in capillary electrophoresis, which is ideal for method development and for student training. The injector consists of two parts that are manufactured by three-dimensional printing (STL and STEP files are included as ESI). One part is immobile and holds an electrode for powering electrophoresis and a gas line for pressurized injection and pumping fluids through the capillary. The second part is removable and is used to hold washing solutions, separation electrolyte, or sample. Conventional machining is used to tap holes to hold the electrode, separation capillary, gas line, and safety interlock. The system is used for either pressure or electrokinetic sample injection, and can be used to pump fluids through the capillary for changing background electrolytes and reconditioning the capillary between runs. We coupled the injection system to our high-dynamic range laser-induced fluorescence detector and evaluated the system by performing capillary zone electrophoresis on solutions of fluorescein. Electrokinetic injection produced a linear response across five orders of magnitude dynamic range (slope of the log-log calibration curve was 1.02), concentration detection limits of 5 pM, and mass detection limits of 1 zmol. Pressure injection produced a linear response across at least four orders of magnitude (slope of the log-log calibration curve was 0.92), concentration detection limits of 2 pM, and mass detection limits of 10 zmol.

STUDY OF COMPOSITION AND STRUCTURE OF NLMK BF No. 6 HEARTH SCULL. Report 2

Resistance of hearth walls lining and their joint with hearth plug considerably governs a blast furnace (BF) campaign duration. Development of hearth design of modern BFs provides a high effective heat sink by copper cooling plates and application for the lining carbonaceous blocks having high heat conductivity, which causes stable scull formation. Study of the composition and the structure of the scull is an important and actual task to provide the highest technical and economical indices of blast furnace production, increasing of the furnaces campaign duration. It was shown that the scull in the hearth zone has a laminated structure. It was established that content of titanium compounds (oxide, carbides and nitrides) in the scull is low. Zinc buildups were not found on the carbonaceous refractories of the hearth walls lower the tap hole. Considerable content of zinc compounds was revealed in the scull of brickwork of the hearth top, in the area of tap holes and hole channels, on the hearth refractories. It was found that basic components of the scull were represented by carbon in the form of graphite, metal (mainly in the form of α-Fe) and slag, amount of which was nincreasing from the lower part of the hearth to the upper one while the content of metal and graphite in it was decreasing.

Probabilistic analysis of aluminium production explosion accidents based on a fuzzy Bayesian network

Explosion accidents of molten aluminium in contact with water during aluminium production often occur and may cause injury and death. In this paper, a fuzzy Bayesian network (BN) was employed to probabilistically analyse the explosion accident of molten aluminium in contact with water. A fault tree-Bayesian network (FT-BN) model was established in the cause-effect analysis of the explosion accident, including three processes: electrolysis, molten aluminium transportation and aluminium casting. Fifty-three nodes were proposed in the model to represent the evolution process of the explosion accident from failure causes to consequences. Furthermore, the occurrence probabilities of basic events (BEs) were determined by expert judgement with weighted treatments based on fuzzy theory. By giving certain occurrence probabilities of each BE, the probability of an explosion accident was estimated. Subsequently, importance measures were assessed for each BE, which could reflect the impact on the occurrence of the top event (TE), and the final ranks were provided. The results indicate that using wet ladles and tools, water on the ground, breakage of the tap hole, damage to the casting mould, and leakage of circulating water are five main problems that cause explosion accidents. Safety advice was provided based on the analysis results. This study can help decision makers improve the safety management of aluminium production.

A Review of Ferroalloy Tapping Models

Tapping is an important furnace operation in the ferroalloy industry and poses a number of complex and coupled challenges of both practical and economical importance. Owing to the hazardous high-temperature conditions surrounding the tap hole, the application of various modeling techniques allows for development and acquisition of both scientific and engineering knowledge of the process through physical or numerical proxies. In this review, earlier work on modeling of ferroalloy tapping is summarized and main principles of the tapping process and multiphase interaction of slag and metal are discussed and summarized. The main focus is on drainage of slag and alloys, but some attention will also be given to metal loss, metal overflow and health, safety and environment. Our review shows that although considerable progress has been made in computational capability over the last decades, However, it is clear that research and development in the field of ferroalloy furnace tapping remains at a relatively nascent stage. The most progress up to date has happened in the area of so called reduced-order models. Such models are robust and simple, and may be easily fitted to process data from a particular operation in order to develop tailored solutions. Such models are more easily combined with software and instruments, ultimately enabling improved automation, process control and ultimately improved tapping consistency.