The investigations of gas-powder two phase flow in packed bed

Abstract

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

Quantification of powder holdups in the presence of a cavity with lateral gas–powder injection in a packed bed

“…Many investigators have observed such trends quantitatively in static holdups in cylindrical apparatus experiments. [3,12,21,31] Similar results are reported for dynamic holdups in cylindrical apparatus experiments. [6] One of the authors in the literature predicted similar results by computation.…”

Cold-model numerical study of raceway shape and size effect on gas and fines flow behaviour in packed bed between the raceway and cohesive zone

“…Mathematical framework by various previous researchers has considered a constant voidage model for the packed bed [17][18][19][20], a two-fluid model for the gas and fines flow [21,22], an isostress based model for determining the raceway shape and size [23,24], and a correlation-based static holdup [24]. Similar mathematical framework has been employed by several researchers to replicate the holdup [9,22,[25][26][27][28][29][30] and pressure loss characteristics [31,32] in a blast furnace. However, these studies have neglected certain critical aspects of the blast furnace.…”