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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Study on the Fluid Flow Characteristics of Coherent Jets with CO{sub 2} and O{sub 2} Mixed Injection in Electric Arc Furnace Steelmaking Processes

As an efficient oxygen supplying technology, coherent jets are widely applied in electric arc furnace (EAF) steelmaking processes to strengthen chemical energy input, speed up smelting rhythm, and promote the uniformity of molten bath temperature and compositions. Recently, the coherent jet with CO{sub 2} and O{sub 2} mixed injection (COMI) was proposed and demonstrated great application potentiality in reducing the dust production in EAF steelmaking. In the present study, based on the eddy dissipation concept model, a computational fluid dynamics model of coherent jets with COMI was built with the overall and detailed chemical kinetic mechanisms (GRI-Mech 3.0). Compared with one-step combustion reaction, GRI-Mech 3.0 consists of 325 elementary reactions with 53 components and can predict more accurate results. The numerical simulation results were validated by the combustion experiment data. The jet behavior and the fluid flow characteristics of coherent jets with COMI under 298 K and 1700 K (25 °C and 1427 °C) were studied and the results showed that for coherent jets with COMI, the chemical effect of CO{sub 2} significantly weakened the shrouding combustion reactions of CH{sub 4} and the relative importance of the chemical effect of CO{sub 2} increases with CO{sub 2} concentration increasing. The potential core length of coherent jet decreases with the volume fraction of CO{sub 2} increasing. Moreover, it also can be found that the potential core length of coherent jets was prolonged with higher ambient temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Study on the Impact Characteristics of Coherent Supersonic Jet and Conventional Supersonic Jet in EAF Steelmaking Process

Supersonic oxygen-supplying technologies, including the coherent supersonic jet and the conventional supersonic jet, are now widely applied in electric arc furnace steelmaking processes to increase the bath stirring, reaction rates, and energy efficiency. However, there has been limited research on the impact characteristics of the two supersonic jets. In the present study, by integrating theoretical modeling and numerical simulations, a hybrid model was developed and modified to calculate the penetration depth and impact zone volume of the coherent and conventional supersonic jets. The computational fluid dynamics results were validated against water model experiments. The results show that the lance height has significant influence on the jet penetration depth and jet impact zone volume. The penetration depth decreases with increasing lance height, whereas the jet impact zone volume initially increases and then decreases with increasing lance height. In addition, the penetration depth and impact zone volume of the coherent supersonic jet are larger than those of the conventional supersonic jet at the same lance height, which illustrates the advantages of the coherent supersonic jet in delivering great amounts of oxygen to liquid melt with a better stirring effect compared to the conventional supersonic jet. A newly defined parameter, the k value, reflects the velocity attenuation and the potential core length of the main supersonic jet. Finally, a hybrid model and its modifications can well predict the penetration depth and impact zone volume of the coherent and conventional supersonic jets.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Influence of the Carrier Gas Species on CaO-Gas Mixed Injection in the EAF Steelmaking Process

In the process of electric arc furnace (EAF) steelmaking, usually the lime powder is sprayed into the molten pool with air as carrier gas to reduce costs. However, because of the nitrogen content requirements in the steel, oxygen or oxygen to mix carbon dioxide was substituted as the carrier gas for the lime powder injection. Lime injection with a burner mode has been reported to promote 100 pct lime injection in the EAF and faster dissolution of lime, but few studies have been made on the effect of the carrier gas on lime powder injection. In this study, four different kinds of carrier gas were used to investigate the influence of carrier gas on lime powder injection in EAF steelmaking. In this study, a CFD model based on the discrete particle model and eddy-dissipation concept model was carried out to investigate the influence of carrier gas species on the CaO-gas mixed injection in EAF steelmaking. The interaction between carrier gas and particles was analyzed, and the influences of carrier gas on the shrouding CH{sub 4} were also analyzed. Results show that the decrease of CO{sub 2} content in the main carrier gas provides better efficiency of the shrouding combustion and more uniform particle distribution.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multi-zone Reaction Kinetics: Model Derivation and Validation

A multi-zone kinetic model coupled with a dynamic slag generation model was developed for the simulation of hot metal and slag composition during the basic oxygen furnace (BOF) operation. The three reaction zones (i) jet impact zone, (ii) slag–bulk metal zone, (iii) slag–metal–gas emulsion zone were considered for the calculation of overall refining kinetics. In the rate equations, the transient rate parameters were mathematically described as a function of process variables. A micro and macroscopic rate calculation methodology (micro-kinetics and macro-kinetics) were developed to estimate the total refining contributed by the recirculating metal droplets through the slag–metal emulsion zone. The micro-kinetics involves developing the rate equation for individual droplets in the emulsion. The mathematical models for the size distribution of initial droplets, kinetics of simultaneous refining of elements, the residence time in the emulsion, and dynamic interfacial area change were established in the micro-kinetic model. In the macro-kinetics calculation, a droplet generation model was employed and the total amount of refining by emulsion was calculated by summing the refining from the entire population of returning droplets. A dynamic Fe{sub t}O generation model based on oxygen mass balance was developed and coupled with the multi-zone kinetic model. The effect of post-combustion on the evolution of slag and metal composition was investigated. The model was applied to a 200-ton top blowing converter and the simulated value of metal and slag was found to be in good agreement with the measured data. The post-combustion ratio was found to be an important factor in controlling Fe{sub t}O content in the slag and the kinetics of Mn and P in a BOF process.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multizone Reaction Kinetics: Modeling of Decarburization

In a previous study by the authors (Rout et al. in Metall Mater Trans B 49:537–557, 2018), a dynamic model for the BOF, employing the concept of multizone kinetics was developed. In the current study, the kinetics of decarburization reaction is investigated. The jet impact and slag–metal emulsion zones were identified to be primary zones for carbon oxidation. The dynamic parameters in the rate equation of decarburization such as residence time of metal drops in the emulsion, interfacial area evolution, initial size, and the effects of surface-active oxides have been included in the kinetic rate equation of the metal droplet. A modified mass-transfer coefficient based on the ideal Langmuir adsorption equilibrium has been proposed to take into account the surface blockage effects of SiO{sub 2} and P{sub 2}O{sub 5} in slag on the decarburization kinetics of a metal droplet in the emulsion. Further, a size distribution function has been included in the rate equation to evaluate the effect of droplet size on reaction kinetics. The mathematical simulation indicates that decarburization of the droplet in the emulsion is a strong function of the initial size and residence time. A modified droplet generation rate proposed previously by the authors has been used to estimate the total decarburization rate by slag–metal emulsion. The model’s prediction shows that about 76 pct of total carbon is removed by reactions in the emulsion, and the remaining is removed by reactions at the jet impact zone. The predicted bath carbon by the model has been found to be in good agreement with the industrially measured data.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multizone Reaction Kinetics: Modeling of Manganese Removal

In the earlier study, a dynamic model for the BOF process based on the multizone reaction kinetics has been developed. In the preceding part, the mechanism of manganese transfer in three reactive zones of the converter has been analyzed. The study predicts that temperature at the slag–metal reaction interface plays a major role in the Mn reaction kinetics. Further, mathematical treatments to simulate the transient rate parameters associated with each reaction interface have been developed. The model calculations of Mn removal rate obtained from different zones of the converter predicts that the first stage of the blow is dominated by the oxidation of Mn at the jet impact zone, albeit some additional Mn refining has been observed as a result of the oxidation of metal droplets in emulsion phase. The simulation result shows that the reversion of Mn from slag to metal primarily takes place at the metal droplet in the emulsion due to an increase in slag–metal interface temperature during the middle stage of blowing. In the final stage of the blow, the competition between simultaneous reactions in jet impact and emulsion zone controls the direction of mass flow of manganese. Further, the model prediction shows that the Mn refining in the emulsion is a strong function of droplet diameter and the residence time. Smaller sized droplets approach equilibrium quickly and thus contribute to a significant Mn conversion between slag and metal compared to the larger sized ones. The overall model prediction for Mn in the hot metal has been found to be in good agreement with two data sets obtained from different size converters reported in the literature.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A Novel Flash Ironmaking Process

The project goal is to develop an entirely new transformational process for alternate ironmaking based on the direct gaseous reduction of iron oxide concentrates in a flash reduction process, with the ultimate objective of significantly increasing energy productivity (by reducing energy consumption by up to 57 %) and reducing environmental emissions, especially CO 2 emissions, versus the conventional blast furnace ironmaking route.The Novel Flash Ironmaking Process uses gaseous reducing agents, such as natural gas, hydrogen, other syngas, or a combination thereof. The proposed technology is to be applied to the production of iron as a feed to the steelmaking process, eventually replacing the blast furnace and other alternate ironmaking processes. The process can also be a part of a continuous direct steelmaking process.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Sound Waves on Decarburization Rate of Fe-C Melt

Sound waves have the ability to propagate through a gas phase and, thus, to supply the acoustic energy from a sound generator to materials being processed. This offers an attractive tool, for example, for controlling the rates of interfacial reactions in steelmaking processes. This study investigates the kinetics of decarburization in molten Fe-C alloys, the surface of which was exposed to sound waves and Ar-O{sub 2} gas blown onto the melt surface. The main emphasis is placed on clarifying effects of sound frequency, sound pressure, and gas flow rate. A series of water model experiments and numerical simulations are also performed to explain the results of high-temperature experiments and to elucidate the mechanism of sound wave application. This is explained by two phenomena that occur simultaneously: (1) turbulization of Ar-O{sub 2} gas flow by sound wave above the melt surface and (2) motion and agitation of the melt surface when exposed to sound wave. It is found that sound waves can both accelerate and inhibit the decarburization rate depending on the Ar-O{sub 2} gas flow rate and the presence of oxide film on the melt surface. The effect of sound waves is clearly observed only at higher sound pressures on resonance frequencies, which are defined by geometrical features of the experimental setup. The resonance phenomenon makes it difficult to separate the effect of sound frequency from that of sound pressure under the present experimental conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Grid-Interactive Steelmaking with Hydrogen (GISH)

"Grid-Interactive Steelmaking with Hydrogen (GISH)," aims to advance the use of hydrogen in steelmaking processes in a flexible manner with natural gas based on renewable energy availability to reduce carbon emissions in steelmaking. The project is a collaboration involving multiple partners and spans from October 1, 2020, to January 31, 2025, with the report dated May 25, 2025.

03 NATURAL GAS↗
DOE OSTI2022

Observational process data analytics using causal inference

Voluminous process data are available with the paradigm shift toward smart manufacturing. However, most historical data are observational, containing noncausal correlations due to confounders and mediators. Estimating causal effects from observational data remains a bottleneck in leveraging them for active applications such as optimization and control. Further, this work aims to introduce a causal modeling framework for analyzing observational process data and extracting quantitative causal information. We demonstrate a real-world application in steel manufacturing where causal inference is used to analyze observational production data and improve the steelmaking process. Additionally, we propose a novel formulation for identifying critical process parameters from observational data, where causal inference is combined with variance-based methods to estimate corresponding risks of interventions to the manufacturing system. The proposed methods are compared with statistical ones to illustrate that causally interpreting statistical correlation leads to problematic results, while the provided workflow generates satisfactory strategies for process improvement.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Numerical Modeling & Size Optimization of Thermal Energy Storage for Iron & Steel Production

Iron and steel production are responsible for 90 million MtCO2 per year in the United States. Hydrogen direct reduction of iron (H2DRI) is a promising pathway for a more sustainable iron production than commercially deployed technologies which rely on natural gas. The H2DRI process requires hydrogen at a temperature of up to 950 degrees C fed into a reduction furnace to produce pellets or briquettes that are used in the downstream iron and steelmaking process. In this work, we propose to use an electrical thermal energy storage (ETES) system, that can use renewable electricity to store high-temperature heat and dispatch it upon demand. Such a system can buffer the H2DRI plant from the variability of electricity prices by charging during curtailment and running the plant from storage during times of peak electricity price. We have developed heat transfer models for two different ETES systems that can be used to heat up hydrogen to the required temperatures: a particle-based ETES and a firebrick ETES. These models are used to evaluate the performance of such a system and support the sizing and preliminary cost estimation. The preliminary results using both models show that designing ETES systems for an industrial-scale H2DRI furnace is feasible. The firebrick ETES system has limited operational duration, which might limit the price buffering effect unless significantly oversized. The particle ETES system heat exchanger has industry-feasible dimensions, but its storage capacity would be decided upon the number of particle storage silos.

25 ENERGY STORAGE↗
DOE OSTI2024

Computational Methods for Multi-Physics Simulation of Melting in Steelmaking

Iron and steel production accounts for approximately 8% of global carbon dioxide (CO) emissions. Pathways to decarbonize include replacing fossil fuels in iron ore reduction and electrifying other steelmaking processes. Iron pellets produced by hydrogen, called Hydrogen Direct Reduced Iron (HDRI), have property differences from those produced using conventional DRI processes. These differences may impact melting in electric arc furnaces (EAF) and other downstream processes. The physical properties of iron pellets vary significantly with temperature during heating, complicating predictions of their behavior. In this project, we seek to develop an integrated simulation, including the fluid flow and convective thermal transport around the pellet particle. We also examine conduction and phase changes within the particle as they impact the melting process. We use adaptive mesh refinement (AMR) to resolve both the changing size of the particle and the complex physics of the interaction between the pellet and the surrounding fluid. We base our simulations on the AMReX-incflo module, which allows large-scale Navier-Stokes simulation while resolving the changing particle size during melting. As we advance our numerical tools, we anticipate an improved understanding of the dynamics of HDRI melting, which will, in turn, accelerate the adoption of low-carbon technologies in the steelmaking industry.

AMReX↗
DOE OSTI2018

Fluid Force-Induced Detachment Criteria for Nonmetallic Inclusions Adhered to a Refractory/Molten Steel Interface

Since nonmetallic inclusions (NMIs) in steel cannot be completely avoided, a greater understanding of their development and evolution during the steelmaking process is required. In particular, this includes the adhesion of microinclusions to the refractory/steel interface in the flow control system between the tundish and the mold. This phenomenon, commonly referred to as clogging, causes losses in productivity and product quality. Inclusions transported from the bulk melt to the boundary layer may adhere to the refractory/steel interface due to formation of a fluid cavity. A detailed model was derived for the detachment of NMIs adhering to a nozzle wall and is based on the local hydrodynamic conditions combined with the specific interfacial properties in the system consisting of the inclusions, the refractories, and the steel. The model is evaluated for three different application-oriented cases. This study has been focused on providing a better understanding of fluid flow in the near-wall region in order to reduce clogging during steelmaking.

42 ENGINEERING↗
DOE OSTI2018

Effect of Shrouding Gas Temperature on Characteristics of a Supersonic Jet Flow Field with a Shrouding Laval Nozzle Structure

Coherent jet technology was been widely used in the electric arc furnace steelmaking process to protect the kinetic energy of supersonic oxygen jets and achieve a better mixing effect. For this technology, the total temperature distribution of the shrouding jet has a great impact on the velocity of the main oxygen jet. In this article, a supersonic shrouding nozzle using a preheating shrouding jet is proposed to increase the shrouding jet velocity. Both numerical simulation and experimental studies were carried out to analyze its effect on the axial velocity, total temperature and turbulence kinetic energy profiles of the main oxygen jet. Based on these results, it was found that a significant amount of kinetic energy was removed from the main oxygen jet when it passed though the shock wave using a high-temperature shrouding jet, which made the average axial velocity of the coherent jet lower than for a conventional jet in the potential core region. However, the supersonic shrouding nozzle and preheating technology employed for this nozzle design significantly improved the shrouding gas velocity, forming a low-density gas zone at the exit of the main oxygen jet and prolonging the velocity potential core length.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Numerical Simulation and Industrial Experimental Research on the Coherent Jet with “CH{sub 4} + N{sub 2}” Mixed Fuel Gas

Coherent jet technology is widely used in the electric arc furnace (EAF) steelmaking process to deliver more energy and momentum into the molten steel bath. Meanwhile, the characteristics of a coherent jet using pure CH{sub 4} as the fuel gas have been well investigated in previous studies. To reduce the consumption of CH{sub 4}, coherent jet technology using “CH{sub 4} + N{sub 2}” mixed fuel gas instead of pure CH{sub 4} was proposed and studied in detail by numerical simulation in the present work. The Eddy Dissipation Concept model, which has detailed chemical kinetic mechanisms, was adopted to model the fuel gas combustion reactions. Experimental measurements were carried out to validate the accuracy of the computational model. The present study shows that the jet characteristics of the main oxygen improve along with the increase of the CH{sub 4} ratio in fuel gas and with the increase of the flow rate of fuel gas. When the CH{sub 4} ratio in the fuel gas is 25 pct, the fuel gas flow rate only has a limited influence on the jet characteristics, unlike the rest of the fuel gas compositions, because a high N{sub 2} proportion deteriorates the combustion performance and leads to severe incomplete combustion. Moreover, a false potential core phenomenon was observed and explained in the present study. Based on the average values, the jet length of a coherent jet with 75 pct CH{sub 4} can achieve 89.8 pct of that with 100 pct CH{sub 4}. Finally, an industrial experiment was carried out on a commercial 100t EAF using coherent jet with 75 pct CH{sub 4}, showing that the average CH{sub 4} consumption was reduced from 3.84 to 3.05 Nm{sup 3} t{sup −1} under the premise of no obvious changes in the other production indexes.

42 ENGINEERING↗
DOE OSTI2018

Similarity Criteria for the Study of Removal of Spherical Non-metallic Inclusions in Physical Models of Continuous Casting Tundishes: A More Fundamental Approach

Physical modeling is widely used for studying steelmaking processes. The accuracy of this technique depends on the use of appropriate similarity criteria during experimental design. The present work deduced rigorously the similarity criteria for the study of spherical non-metallic inclusions in isothermal physical models of tundishes. Initially, macroscopic quantities were used to simplify the multiphase problem. Then, the similarity criteria were obtained from the dimensionless form of the exact equation of motion for an inclusion in Stokes regime. The validity range of these criteria was discussed and they were compared with common literature practice. Some practical considerations were also presented. This work clarifies various implicit assumptions usually adopted in literature. Additionally, a restrictive criterion to choose the density of the inclusion simulating particles was obtained, which can be satisfied, for example, by hollow glass particles in water models. This criterion is necessary to adequately describe the inclusion motion in regions where fluid elements suffer strong acceleration (e.g., inside nozzles, near flow controllers or in the entering fluid jet). Moreover, it was established an upper limit for the concentration of particles injected in the inlet nozzle of physical models, which do not simulate the phenomenon of inclusion aggregation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Reaction Behaviors of Al-Killed Medium-Manganese Steel with Glazed MgO Refractory

In order to understand the reaction mechanism of Al-killed medium-Mn steel with glazed MgO refractory, some laboratory experiments were conducted at [1873 K (1600 °C)]. The refractory rods were glazed by four different basicity slags, and inserted into liquid steel (Mn:5.5 mass pct) for different times. The results show that MgO refractory can react with medium-Mn steel to generate (Mn, Mg)O solid solution with even (Mn, Mg)O-Al{sub 2}O{sub 3} spinel at the boundary of the refractory. When a glaze layer is formed at the edge of a MgO refractory, the glaze layer will supply inclusions into liquid steel and may act as a protection layer for the refractory. Although the glaze could also react with dissolved Mn in steel to generate MnO in both the glaze and refractory, the MnO contents in both the glaze and refractory are evidently lower than that without glaze. The reaction between glazed MgO refractory and liquid steel is influenced by the basicity of the glaze layer. High-basicity slag would hinder the generation of MnO in both the glaze and refractory. Therefore, lower-basicity glaze needs to be avoided for the steelmaking process of medium-Mn steel grades.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Al{sub 2}O{sub 3} Addition on Mineralogical Modification and Crystallization Kinetics of a High Basicity BOF Steel Slag

Basic oxygen furnace (BOF) steel slag is a main byproduct that is produced during the converter steelmaking process. The volume instability and fast crystallization of BOF slag limits its added-value application. This article aims to understand the effect of Al{sub 2}O{sub 3} on the mineralogical modification and crystallization kinetics of a high basicity BOF steel slag. Continuous cooling transformation and time–temperature–transformation curves were constructed to determine the crystallization characteristics of BOF slag. The critical cooling rate to vitrify the slag was experimentally obtained. The crystallization sequence was clarified by integrating in situ and post-mortem observations with thermodynamic calculations. The results suggest that the addition of Al{sub 2}O{sub 3} can effectively remove free lime, decrease the melting point, and improve the glass formation ability of the high basicity BOF slag. Undercooling the slag is enhanced by increasing the cooling rate and/or adding Al{sub 2}O{sub 3}. By steering the addition of Al{sub 2}O{sub 3} and the cooling rate, BOF slag can be modified to obtain a more amorphous phase, presenting an enhanced potential to be a binder for added-value applications.

36 MATERIALS SCIENCE↗