Effect of Foamy Slag Height on Hot Spots Formation inside the Electric Arc Furnace Based on a Radiation Model

Sanchez, J.L.G.; Conejo, Alberto N.; Ramírez-Argáez, Marco A.

doi:10.2355/isijinternational.52.804

Cited by 28 publications

(55 citation statements)

References 4 publications

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“…By computational fluid dynamics modeling of AC electric arcs, it was found that to increase the efficiency in the power delivered to the arc; the arc length should be increased. 7) It is well known, from arc furnace physics theory and confirmed for many EAF operation experiences that lengthening the arcs increases arc radiation.…”

Section: Arc Power Under Unstable Arc Conditionsmentioning

confidence: 94%

“…According to computational fluid dynamics (CFD) simulations, 7) the power dissipated by AC electric arc is transferred by three different mechanisms: by convection , by radiation and by the electrons flow . Energy transferred by convection accounts for 70%, while the energy transferred by radiation is around 24% and the energy transferred by the flow of electrons, , represents only about 3% of the total energy transferred from the arc.…”

Section: Arc Thermal Radiationmentioning

confidence: 99%

“…5 using Computational Fluid Dynamic (CFD) methods. The electric arcs has been also modeled by means of the channel arc model applied by Sánchez, Ramírez & Conejo 7) to estimate the power delivery by the arc to the heat transfer mechanism of radiation, convection and conduction.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Theoretical Estimation of Peak Arc Power to Increase Energy Efficiency in Electric Arc Furnaces

et al. 2013

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This research work introduces the concept of "useful arc power" and the thermal model, first introduced by Dittmer and Krüger, to establish the arc length at any stage of the heat in Alternate Current Electric Arc Furnaces (AC-EAF), based on the estimation of the fraction of the energy transferred to the metallic load by radiation. Radiation is the most effective way to transfer heat in an arc furnace in presence of metallic scrap (bore-in and early meltdown). On the other hand, if the arc is not adequately covered with slag, radiation is extremely dangerous to the furnace integrity. When the furnace is fully loaded, scrap protects the walls and cooling panels and then arc radiation must be maximized. To increase energy efficiency, and at the same time reduce circuit power losses, the arc length should be controlled. However, arc instability prevents to increase radiation, as desired, and a compromise must be reached between arc length and arc stability. In this work AC-EAF electric circuit is modeled and analyzed under different heat stages. Electrodes, anode and cathode, fall regions can be considered as energy losses and their associated power may be deducted for the estimation of the "useful arc power" and for the definition of the operational currents in the heat process, particularly during flat bath conditions (late meltdown and refining). As a result of the present study it is proved that current setpoints play an important role for energy saving at any stage of the heat. Finally, experimental results obtained from an industrial steel factory validate this approach to optimize the electrical energy consumption per ton of liquid steel in AC-EAF.

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Section: Arc Power Under Unstable Arc Conditionsmentioning

confidence: 94%

Section: Arc Thermal Radiationmentioning

confidence: 99%

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Theoretical Estimation of Peak Arc Power to Increase Energy Efficiency in Electric Arc Furnaces

et al. 2013

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“…Arc stability is estimated by measuring harmonic content of the transformer's secondary side voltage or line current. Notice that the stability concept, referred in this article, is neither the plasma arc stability as defined in, 6,14) nor the stability of the electric power system, but it may have some relation with both of them. The electrical arc voltage can be modeled, in spite of its non-linearity, as a sum of harmonic voltages according with Fourier analysis.…”

Section: Harmonics and Thd As Arc Stability Indexmentioning

confidence: 99%

Virtual Neutral to Ground Voltage as Stability Index for Electric Arc Furnaces

et al. 2011

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This article proposes an arc stability index for Electrical Arc Furnaces (EAF) based on the real-time processing of the line to ground three-phase voltage measurements typically available at the secondary side of the EAF's power transformer. This methodology uses the definition of a virtual neutral for the open delta connection to calculate the neutral to ground voltage waveform and its Root Mean Square value that can be considered in a simple formula as stability indicator of the arc itself and for the power delivery to the arc. This proposed stability indicator may be used for process monitoring and power control.

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“…Since electric arcs are the main source of energy in electric arc furnaces, the electric energy provided by them represents Many models have been developed to simulate electrical arcs among which the MHD model, 4,5) Cassie-Mayr model, 6) channel arc model (CAM) 7) could be mentioned as examples. MHD models are more comprehensive than other types and include calculation of arc velocity profile, pressure profile and temperature profile; 4) however, the flaw of such models is that their parameterization and implementation require a large number of experimental data. 6) On the other hand, Cassie-Mayr arc models are easier to parameterize and they could be integrated into broader EAF models; but, they are usually used to model low arc powers.…”

Section: Introductionmentioning

confidence: 99%

Low Computational-complexity Model of EAF Arc-heat Distribution

et al. 2015

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The paper presents a computational model and the corresponding algorithm for estimating the arc energy distribution to conductive, convective and radiative heat transfer in an electric arc furnace (EAF). The proposed algorithm uses channel arc model (CAM) in order to compute the distribution of the arc energy through empirical equations (to approximate arc radius), ideal gas law (to approximate arc density) and results of magneto-hydro-dynamic (MHD) models (to approximate arc pressure, temperature and velocity). Results obtained using the proposed algorithm are comparable with other similar studies; however, in contrast to other arc-energy distribution models, this model requires only two input variables (arc length and arc current) in order to calculate the energy distribution. Furthermore, simple algebraic equations used in the algorithm ensure minimal computational load and consequently lead to short calculation times which are approximately one hundred thousand (100 000) times smaller than solving the MHD model equations, making the algorithm suitable for real-time applications, such as smart monitoring and model-based control. The algorithm has been validated by two different approaches. First, the simulation results have been compared to a study dealing with arc-heat distribution in plasma arc furnace; and second, the proposed arc module has been integrated into the frame of a comprehensive EAF model in order to estimate the EAF temperature levels and compare them with operational EAF measurements. Both validations show high levels of similarity with the comparing data.KEY WORDS: arc current; arc heat distribution; arc length; channel arc model; EAF.approximately 75-85% of the total energy in low to medium power furnaces and approximately 50-60% of the total energy in ultra-high power furnaces (UHP).3) Implementing an accurate arc module in a comprehensive model-based EAF control, which ensures optimal control of arc length and slag height can lead to substantial energy saving and associated cost reduction. If a total energy reduction in a 200 ton UHP EAF with approximate annual production of 675 000 tones is 50 kWh/ton, with an assumption of 25 kWh/ton being the electrical energy, with the price of 10 $Cent/kWh, total annual energy savings will be equivalent to 1.7 million $ per year.It is known that the heat generated by the arcs is dissipated into the furnace by all three mechanisms of heat transfer (convection, conduction and radiation); however, the amount of the heat, transferred by each mechanism varies according to several factors, such as arc length, arc current, slag height, stage of melting etc. Development of a computational model of the arc, which allows estimation of the arc-heat distribution should therefore include all three types of heat transfer mechanisms, which can also be used to obtain the overall energy balance of the EAF. Application of such models may provide appropriate tools for optimizing the energy flow or use of model-based control systems in the EAFs.

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Effect of Foamy Slag Height on Hot Spots Formation inside the Electric Arc Furnace Based on a Radiation Model

Cited by 28 publications

References 4 publications

Theoretical Estimation of Peak Arc Power to Increase Energy Efficiency in Electric Arc Furnaces

Theoretical Estimation of Peak Arc Power to Increase Energy Efficiency in Electric Arc Furnaces

Virtual Neutral to Ground Voltage as Stability Index for Electric Arc Furnaces

Low Computational-complexity Model of EAF Arc-heat Distribution

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