Laboratoriumsuntersuchungen über die Reduktionskinetik von Eisenerzen in der Wirbelschicht. Identifizierung des geschwindigkeitsbestimmenden Teilschritts. Ableitung der kinetischen Prozeßgleichung. Bestimmung der Modellparameter. Besprechung der präsentierten verallgemeinerten Prozeßgleichung.
Gas-powder two-phase flow in packed beds was investigated and the results are presented in this paper. The experimental system, in which the glass powder and air gas were injected into the lower part of the packed bed allowed the estimation of the influence of gas velocity, powder feed rate, powder and packed particles diameter on pressure loss and total hold up of powder in the packed bed. On the base of the experimental results, a one-dimensional mathematical model for gas-powder two-phase flow in the packed bed was developed. This model allows satisfactory prediction of the pressure loss and the hold ups of powders. The maximum deviation between calculated and measured values was less than ±15%. Futhermore, the conditions when the blockade of the flow occurs were defined. The additional pressure loss (expressed by Fk) due to the gravitional force of powders and the collision and the friction between powders and 1.8462 74.13packed particles, was correlated with Froude number as: Fk = -_ . + .._ -for the void fraction in the packed bed EO of between 1' ;.2 F)0.7309) 1.1670 0.36 to 0.410r Fk =--2-+ 8181.10 for EO =0.42. r; Untersuchungen zur zweiphasigen (Gas + Staub) Durchstromung einer Stoffschicht. Untersucht wurde die zweiphasige Durchstromung (Gas + Staub) einer Stoffschicht: die Ergebnisse werden vorgestellt. FOr ein Modellsystem (Stoffschicht aus Glaskugeln und Glasstaub) wurde der EinfluB der Gasgeschwindigkeit, Staubmenge im Gas, GroBe der Staubpartikel sowie der Stoffschichtpartikel auf den Stromungswiderstand und auf die Menge des eingeschlossenen Staubes in der Schicht bestimmt. Auf der Basis der Laboruntersuchungen wurde ein mathematisches eindimesionales Modell entwickelt, das die zweiphasige Durchstrornunq (Gas + Staub) der Stoffschicht beschreibt. Das Model berOcksichtigt den eingeschlossenen Staub und den Druckverlust in der Schicht. Mit diesem Modell konnen der Stromungswiderstand und die in der Schicht eingeschlossene Staubmenge mit einer Genauigkeit von ±15% berechnet werden. Weiterhin wurde die Abhangigkeit eines Koeffizienten, der den zusatzlichen Widerstand, der durch die Gravitation, den ZusammenstoB und die Reibung der Staubpartikel verursachten EinfluB zusammenfaBt, von der Froude-Zahl Fk = 1.84~2+ (~~713~9) berechnet: G{) liegt steel research 71 (2000) NO.8
The investigations of reducing Fe1‐xO in liquid state with H2+Ar mixtures, in top blowing stream of gas reactor, by using thermobalance method have been carried out. To make the system more homogeneous pure iron crucibles were used in the experiment. The experiments were carried out in the range of gas flow rate V = (5+80) · 10−6 m3/s and in 1723 K. Reduction rate depends on hydrogen partial pressure and flow rate of gas mixture. The logarithm of apparent reduction rate constant is a linear function of logarithm of gas flow rate. In experimental conditions of this work, the initial rate of reduction satisfies the relation . Thus it has been shown that the reduction process is controlled by the mass transfer in the gaseous phase. Sherwood numbers obtained from observed values of reduction rates and empirical equation of the gas‐phase mass transfer rate are correlated by equation . The values of mass transfer coefficient in gas phase calculated from Sherwood numbers are consistent with the values of apparent reduction rate constant and with estimated rate constant of chemical reaction of liquid Fe1‐xO reduction.
An approach to the identification of the parameters of burden distribution in the upper part of the blast furnace is presented in this paper. For the purpose of quantitative evaluation of these parameters a 1:10 small – size model of the bell‐less top developed by Paul Wurth was used. This identification was executed in the following stages: the construction of the bell‐less top small – size model for the investigations (among others calibration of the model and materials), modelling of the burden distribution for the real charging systems, measurements of the layer geometry and the particle size segregation for the following layers in the modelled charging system, data processing to obtain an analytical description of the burden distribution. Computer methods were applied to process the experimental data. In this paper, a mathematical description of burden distribution and a numerical alghorithm for the calculation of the burden distribution parameters are presented. The results of this identification may be utilized in mathematical modelling of the gas flow in the blast furnace and in the gas flow distribution control in the upper part of the blast furnace.
Erstellung eines Modells für den Verlauf des Angriffs von Alkalien auf kohlenstoff‐ und graphithaltige Auskleidungen des Hochofens. Überlegung zur Steigerung ihrer Haltbarkeit.
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