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Influence of bed particle size on gas-powder two phase flow conditions in descending packed bed. Model investigation (3D physical model)

100%

Panic B.

tom Vol. 55, nr 2

567--572

Purpose: The aim of the research is to create basis for introduction of mathematical model for two phase flow in descending packed bed. Design/methodology/approach: Iron obtaining from ore in shaft furnace is connected with accumulation of small particles inside the furnace, which can cause increased gas flow resistance. It is important that no flow disturbances occur. Hence researches were conducted to model (construction of 3D physical model) the flow of gas with powder through two bed types. Findings: Intense accumulation of both powder fractions at the bottom of the bed was noted. Between analysed bed types, a large radial diversification of static pressure has been revealed occurring on the nozzles level. Two reasons of such diversification were identified. Research limitations/implications: Radial changes of static pressure and gas flow resistance along bed height were registered (physical model 3D). Radial distribution of analysed bed was investigated. Amount of powder accumulated in bed was measured with division on “dynamic” and “static” powder. 2D models provide excellent visualization of the occurring phenomena. In full 3D visualization is much more difficult but they mirror real conditions in a better way. Next stage of the research will be conducted with real materials. Practical implications: The developed calculation procedure could be used in flow and its disturbances evaluation in real shaft metallurgical units. Originality/value: In 3D model “static” powder (with its radial distribution) at the tuyere level and in the higher part of bed was measured.

Znaczenie struktury porowatej w modelowaniu procesu redukcji tworzyw żelazodajnych w stanie mięknięcia

51%

Dankmeyer-Łączny J. , Panic B. , Buzek J.

tom Vol. 72, nr 5

268-271

Oceniając wpływ mięknięcia na szybkość redukcji spieków żelazodajnych autorzy stwierdzają silną korelację liniową dla zależności szybkość redukcji w funkcji malejącej porowatości. Mięknąca faza krzemianowa zamyka pory, co prowadzi do znaczącego zaniku porowatości. Potwierdziły to bezpośrednie obserwacje mikroskopowe procesu redukcji i pomiary ilościowe porowatości. Dla redukcji w stanie mięknięcia zaproponowano koncepcję wykorzystania modelu redukcji dla stanu stałego, wrażliwego na zmiany porowatości.

Investigating the influence of softening on reduction rate of iron oxide sinters, the authors confirm strong linear correlation for the dependence: reduction rate - decreasing porosity. Silicate phase softens filling the pores and causing the loss of porosity. It was confirmed by direct microscope examinations and quantitative measurements of pore structure. Reduction model in solid state sensitive to porosity changes is proposed to describe reduction in softening state.