Dynamic process models for on-line observation of the vacuum tank degassing process

Kleimt, B.; Cappel, Jürgen; Hoffmann, J.; Sheng, Dong; Landa, S.

doi:10.1051/metal:2003121

Cited by 6 publications

(5 citation statements)

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“…In addition to this steel exchange, for the vessel the degassing reaction under vacuum is described by a first order differential equation of a diffusion process in liquid steel [2]:…”

Section: Alloying and Deoxidationmentioning

confidence: 99%

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Dynamic model for on-line observation of the current process state during RH degassing

2001

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Based on the principles of thermodynamics and reaction kinetics, a dynamic model for the vacuum circulation (RH) process was developed. It comprises decarburisation, oxygen removal, dehydrogenation, denitrogenation and the course of steel temperature. The process model was validated by comparison of simulation results with measured process data from the RH/1 plant of Voest Alpine Stahl Linz (VASL). At this plant, it is used for on-line observation of the contents of carbon, oxygen, hydrogen and nitrogen as well as the steel temperature. Based on cyclically measured values of vessel pressure, lift gas flow rate as well as waste gas flow rate and composition, the current heat status is calculated reliably. The accuracy of the carbon balance with measured waste gas values was improved remarkably by a model-based correction calculation. The on-line process observation system provides the operator with valuable information on the progress of vacuum treatment. Dynamisches Modell zur on-Iine-Beobachtung des aktuellen ProzeBzustands wiihrend derEntgasung in der RH-Anlage. Basierend auf thermodynamischen und reaktionskinetischen Grundlagen wurde ein dynamisches Modell tur die Vakuum-Umlauf-(RH-) Entgasung entwickelt. Es umfaBt die Entkohlung, den Sauerstoffabbau, die Dehydrierung, die Entstickung und den Verlauf der Stahltemperatur. Das ProzeBmodell wurde uber den Vergleich von Simulationsergebnissen mit ProzeBmeBwerten der RH/1-Anlage der Voest Alpine Stahl Linz verifiziert. An dieser Anlage wird das Modell zur on-line-Beobachtung der Gehalte von Kohlenstoff, Sauerstoff, Wasserstoff und Stickstoff sowie der Stahltemperatur genutzt. Anhand der zyklisch erlaBten MeBwerte fur GefaBdruck, F6rdergasdurchfluB sowie Abgas-durchfluB und -analyse wird der aktuelle ProzeBzustand zuvsrlasslq berechnet. Die Genauigkeit der Kohlenstoffbilanz uber die Abgas-meBwerte konnte durch eine modellbasierte Korrekturrechnung deutlich verbessert werden. Die on-line-ProzeBbeobachtung stellt dem Bediener Informationen uber den Verlauf der Vakuumbehandlung zur Verfuqunq.

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“…In addition to this steel exchange, for the vessel the degassing reaction under vacuum is described by a first order differential equation of a diffusion process in liquid steel [2]:…”

Section: Alloying and Deoxidationmentioning

confidence: 99%

“…In addition to the mass transfer in the liquid phase, for denitrogenation also the reaction at the liquid/gas interface has to be taken into account [5]. This means that in equations (2) and (3) the equilibrium content NQ is diluted by the process gas with the flow rate QD:…”

Section: Alloying and Deoxidationmentioning

confidence: 99%

Dynamic model for on-line observation of the current process state during RH degassing

2001

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“…Bubble behavior such as bubble size, bubble frequency, bubble rising velocity and bubble distribution etc. greatly influences the removal efficiency of harmful dissolved gases and undissolved nonmetallic inclusions [2]. However, at high gas flow rate, large bubbles are generally formed due to coalescence when gases are released from the exits of these porous plugs, nozzles and orifices, which leads to a lower area of gas-liquid interface for metal refining [3].…”

Section: Introductionmentioning

confidence: 99%

Effect of Hole Distance and Hole Number on Bubble Behavior during Gas Injection with Multi-Hole Orifices

Jiang

Cheng

2011

AMR

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Physical model experiments have been performed to clarify the effect of hole distance and hole number of multi-hole orifices on bubble behavior during metal refining process. It is found kA/V firstly decreases and then increases with the hole distance increasing. However, kA/V shows little further increase when hole distance exceeds a critical value. There exists an optimal hole distance for the multi-hole orifice, which is dependent on the gas flow rate, the hole diameter and the hole number in the multi-hole orifice. kA/V firstly increases with the hole number increasing, and then remains unchanged when hole number exceeds a critical value. There also exists an optimal hole number for the multi-hole orifice, which is closely related to the gas flow rate.

show abstract

“…Bubble behavior such as bubble size, bubble frequency, bubble rising velocity etc. significantly influences the removal efficiency of harmful dissolved gases and undissolved nonmetallic inclusions [2]. However, at high gas flow rate, large bubbles are generally formed due to coalescence when gases are released from the exits of these porous plugs, nozzles and orifices, which leads to a lower area of gas-liquid interface for metal refining [3].…”

Section: Introductionmentioning

confidence: 99%

Effect of Gas Injection with Multi-hole Orifices on Bubble Behavior during Metal Refining

Jiang

Cheng

Yang

2011

AMR

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Cold model experiments have been conducted to make clear the effect of orifices on bubble behavior based on the comparison of 1-hole and 4-hole configurations. It is found that this effect is closely related to the gas flow rate and the orifice configuration. For 1-hole orifices, bubble behavior is influenced by the hole diameter at low gas flow rate. Nevertheless, in the region of high gas flow rate, this effect becomes less obvious. However, bubble behavior is strongly affected even at high gas flow rate when 4-hole orifices are used. It is also shown there exists an optimal distance between holes for 4-hole orifices. Below this value, the hole distance is too small to adequately avoid bubble coalescence in the radial direction. Above this value, little further contribution to avoidance of bubble coalescence can be made, but weight and cost of the orifices will increase.

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Dynamic process models for on-line observation of the vacuum tank degassing process

Cited by 6 publications

References 0 publications

Dynamic model for on-line observation of the current process state during RH degassing

Dynamic model for on-line observation of the current process state during RH degassing

Effect of Hole Distance and Hole Number on Bubble Behavior during Gas Injection with Multi-Hole Orifices

Effect of Gas Injection with Multi-hole Orifices on Bubble Behavior during Metal Refining

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