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1
Content available Elimination of Zinc from Aluminum During Remelting in an Vacuum Induction Furnace
Smalcerz Albert, Blacha Leszek, Węcki Bartosz, Desisa D. G., Łabaj Jerzy, Jodkowski Maciej
Archives of Foundry Engineering
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2022
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Vol. 22, iss. 3
11--18
EN
In this paper, the results of the study on aluminium evaporation from the Al-Zn alloys (4.2% weight) during remelting in a vacuum induction furnace (VIM) are presented. The evaporation of components of liquid metal alloys is complex due to its heterogeneous nature. Apart from chemical affinity, its speed is determined by the phenomena of mass transport, both in the liquid and gas phase. The experiments were performed at 10-1000 Pa for 953 K - 1103 K. A significant degree of zinc loss has been demonstrated during the analysed process. The relative values of zinc loss ranged from 4 to 92%. Lowering the pressure in the melting system from 1000 Pa to 10 Pa caused an increase in the value of density of the zinc evaporating stream from 3.82x10-5 to 0.000564 gxcm-2xs-1 at 953 K and 3.32x10-5 to 0.000421 g xcm-2 for 1103 K. Based on the results of the conducted experiments. it was found that evaporation of zinc was largely controlled by mass transfer in the gas phase and only for pressure 10 Pa this process was controlled by combination of both liquid and gas phase mass transfer.
2
Content available External Mass Transfer Model for Hydrogen Peroxide Decomposition by Terminox Ultra Catalase in a Packed-Bed Reactor
Grubecki I.
Chemical and Process Engineering
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2017
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Vol. 38, nr 2
307--319
EN
It is known that external diffusional resistances are significant in immobilized enzyme packed-bed reactors, especially at large scales. Thus, the external mass transfer effects were analyzed for hydrogen peroxide decomposition by immobilized Terminox Ultra catalase in a packed-bed bioreactor. For this purpose the apparent reaction rate constants, kP, were determined by conducting experimental works at different superficial velocities, U, and temperatures. To develop an external mass transfer model the correlation between the Colburn factor, JD, and the Reynolds number, Re, of the type JD = K Re(n-1) was assessed and related to the mass transfer coefficient, kmL. The values of K and n were calculated from the dependence (am kp-1 - kR-1) vs. Re-1 making use of the intrinsic reaction rate constants, kR, determined before. Based on statistical analysis it was found that the mass transfer correlation JD = 0.972 Re-0.368 predicts experimental data accurately. The proposed model would be useful for the design and optimization of industrial-scale reactors
3
Content available Contribution of liquid-and gas-side mass transfer coefficients to overall mass transfer coefficient in Taylor flow in a microreactor
Sobieszuk P., Ilnicki F., Pohorecki R.
Chemical and Process Engineering
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2014
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Vol. 35, nr 1
35--45
EN
Gas-liquid microreactors find an increasing range of applications both in production, and for chemical analysis. The most often employed flow regime in these microreactors is Taylor flow. The rate of absorption of gases in liquids depends on gas-side and liquid-side resistances. There are several publications about liquid-side mass transfer coefficients in Taylor flow, but the data about gas-side mass transfer coefficients are practically non existent. We analysed the problem of gas-side mass transfer resistance in Taylor flow and determined conditions, in which it may influence the overall mass transfer rate. Investigations were performed using numerical simulations. The influence of the gas diffusivity, gas viscosity, channel diameter, bubble length and gas bubble velocity has been determined. It was found that in some case the mass transfer resistances in both phases are comparable and the gas-side resistance may be significant. In such cases, neglecting the gas-side coefficient may lead to errors in the experimental data interpretation.
4
Content available Effects of Pressure on the Rate of Tin Evaporation From Liquid Iron
Lipart J., Łabaj J., Słowikowski M., Jama D.
Archives of Metallurgy and Materials
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2014
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Vol. 59, iss. 2
825--828
EN
In the paper, tin elimination from liquid iron alloy via low-pressure evaporation has been analysed. The experiments were performed using a single-chamber VIM 20-50 vacuum induction furnace at 1923 K and the operating pressure of 0.05 to 557 Pa.
PL
W prezentowanej pracy dokonano analizy procesu eliminacji cyny z ciekłego stopu żelaza na drodze odparowania w warunkach obniżonego ciśnienia. Eksperymenty realizowano w jednokomorowym indukcyjnym piecu próżniowym V1M 20-50 w temperaturze 1923 K i zakresie ciśnień roboczych od 0.05 do 557 Pa.
5
Content available Effects of pressure on the kinetics of manganese evaporation from the OT4 alloy
Blacha L., Burdzik R., Smalcerz A., Matuła T.
Archives of Metallurgy and Materials
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2013
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Vol. 58, iss. 1
197-201
EN
In the paper, results of the study on manganese evaporation from the OT4 alloy are presented. In the experiments, the effects of pressure on the manganese evaporation kinetics and the stages that limit the evaporation rate were investigated. It was demonstrated that the rate of manganese evaporation from the alloy increased with pressure reduction in the system. When the pressure decreases from 1000 Pa to 10 Pa, the value of overall mass transfer kMn increases from 3.9*10-6 ms-1 to 208.4*10-6 ms-1. At the same time, the manganese fraction in the alloy decreased from 1.49% mass to 0.045% mass. Within the whole pressure range, the analysed evaporation process is diffusion-controlled. For pressures above 50 Pa, the determining stage is transfer in the gaseous phase, while for pressures below 50 Pa, it is transfer in the liquid phase.
PL
W prezentowanym opracowaniu przedstawiono wyniki badań odparowania manganu ze stopu OT4. W ramach prowadzonych eksperymentów badano wpływ ciśnienia na kinetykę procesu odparowania manganu i jednocześnie określono etapy limitujące jego szybkość. Wykazano, że szybkość procesu odparowania manganu ze stopu rośnie wraz z obniżaniem ciśnienia w układzie. Przy obniżeniu ciśnienia od 1000 Pa do 10 Pa wartość ogólnego współczynnika transportu masy kMn rośnie od 3.9x10-6 ms-1 do 208.4x10-6 ms-1. Jednocześnie następowało obniżenie zawartości manganu w stopie od 1.49% mas. Do 0.045% mas.. W całym zakresie ciśnień analizowany proces parowania ma kontrolę dyfuzyjną. Dla ciśnień powyżej 50 Pa etapem determinujacym jest transport w fazie gazowej, a dla ciśnien poniżej 50 Pa transport masy w fazie ciekłej.
6
Content available Kinetics of coper evaporation from the Fe-Cu alloys under reduced pressure
Łabaj J.
Archives of Metallurgy and Materials
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2012
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Vol. 57, iss. 1
165-172
EN
This paper provides an analysis of the results of studies concerning the impact of pressure on the process of copper removal from liquid ferrous alloys by evaporation. The research was conducted in vacuum induction furnace. Iron alloys with 0.509 to 1.518 %wt. Cu content were used for the tests. Kinetics analysis of the examined process was performed for the obtained results and the Speed of the process partial stages was estimated.
PL
W prezentowanej pracy przedstawiono wyniki badań nad możliwością usuwania miedzi z ciekłego żelaza na drodze odparowania. Badania realizowano w indukcyjnym piecu próżniowym. Wykorzystano stopy żelaza zawierające od 0.509 do 1.518% mas. Cu. Dla uzyskanych wyników przeprowadzono analizę kinetyczną badanego procesu i oszacowano szybkości jego etapów cząstkowych.
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